Today's Message Index:
----------------------
1. 04:41 AM - 106 years ago today- Prelude to flight (helspersew@aol.com)
2. 06:49 AM - Re: Push/pull tubes and rod ends (Ameet Savant)
3. 07:53 AM - Re: Push/pull tubes and rod ends (David Paule)
4. 08:28 AM - Re: Push/pull tubes and rod ends (Michael Perez)
5. 08:55 AM - Re: Push/pull tubes and rod ends (Michael Perez)
6. 09:08 AM - Re: Push/pull tubes and rod ends (Lloyd Smith)
7. 09:36 AM - Re: Re: Push/pull tubes and rod ends (Michael Perez)
8. 09:38 AM - Re: Re: Push/pull tubes and rod ends (Michael Perez)
9. 09:42 AM - Re: Re: Push/pull tubes and rod ends (Michael Perez)
10. 09:51 AM - Re: Push/pull tubes and rod ends (Michael Perez)
11. 10:16 AM - Re: Push/pull tubes and rod ends (Michael Perez)
12. 10:21 AM - Re: Re: Push/pull tubes and rod ends (Michael Perez)
13. 10:35 AM - Re: Push/pull tubes and rod ends (Michael Perez)
14. 10:54 AM - Re: Push/pull tubes and rod ends (Michael Perez)
15. 11:02 AM - Re: Push/pull tubes and rod ends (David Paule)
16. 11:12 AM - Re: Push/pull tubes and rod ends (Jack Phillips)
17. 11:17 AM - Re: Push/pull tubes and rod ends (David Paule)
18. 12:36 PM - Re: Push/pull tubes and rod ends (Lloyd Smith)
19. 12:39 PM - Re: Push/pull tubes and rod ends (Lloyd Smith)
20. 01:17 PM - Re: Push/pull tubes and rod ends (Wayne Bressler)
21. 03:04 PM - Re: Push/pull tubes and rod ends (Michael Perez)
22. 03:43 PM - Re: Push/pull tubes and rod ends (Gene Rambo)
23. 03:58 PM - Re: Push/pull tubes and rod ends (Don Emch)
24. 04:06 PM - Re: Push/pull tubes and rod ends (Michael Perez)
25. 04:06 PM - Re: Push/pull tubes and rod ends (Lloyd Smith)
26. 04:11 PM - Re: Push/pull tubes and rod ends (Wayne Bressler)
27. 04:12 PM - Re: Re: Push/pull tubes and rod ends (Michael Perez)
28. 04:19 PM - Re: Re: Push/pull tubes and rod ends -- Chaffinch (Tim Willis)
29. 04:39 PM - Re: Re: Push/pull tubes and rod ends (Rick Holland)
30. 04:54 PM - Re: Push/pull tubes and rod ends (ivan.todorovic)
31. 05:02 PM - Re: Push/pull tubes and rod ends (David Paule)
32. 05:03 PM - Re: Push/pull tubes and rod ends (David Paule)
33. 05:13 PM - Re: Push/pull tubes and rod ends (Lloyd Smith)
34. 05:19 PM - Re: Push/pull tubes and rod ends (ivan.todorovic)
35. 05:24 PM - Re: Re: Push/pull tubes and rod ends (Robert Ray)
36. 05:25 PM - Re: Push/pull tubes and rod ends (Bill Church)
37. 05:43 PM - Re: Push/pull tubes and rod ends (David Paule)
38. 05:58 PM - Re: Re: Push/pull tubes and rod ends (David Paule)
39. 06:08 PM - Re: Push/pull tubes and rod ends (Lloyd Smith)
40. 06:12 PM - Re: Push/pull tubes and rod ends (ivan.todorovic)
41. 06:22 PM - Re: Push/pull tubes and rod ends (Lloyd Smith)
42. 06:43 PM - And the real work begins... (Mark Roberts)
43. 06:55 PM - Re: And the real work begins... (Gary Boothe)
44. 07:24 PM - Re: And the real work begins... (Dave and Connie)
45. 07:25 PM - Re: And the real work begins... (Robert Ray)
46. 07:31 PM - Re: Re: Push/pull tubes and rod ends (Robert Ray)
47. 07:31 PM - Re: Push/pull tubes and rod ends -- Chaffinch (Pieti Lowell)
48. 07:50 PM - some thoughts (Douwe Blumberg)
49. 07:56 PM - Re: some thoughts (Robert Ray)
50. 08:25 PM - Re: And the real work begins... (Ben Charvet)
51. 09:26 PM - Re: And the real work begins... (K5YAC)
Message 1
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| Subject: | 106 years ago today- Prelude to flight |
>From the diary of Orville Wright:
Sunday, October 25, 1903
Kitty Hawk, N.C.
Rain and wind continued through entire night, forming ponds all about camp
. Temperature lower. Air so damp and cold that we made a stove out of a ca
rbide can and built small fire, avoiding smoke as much as possible by sitt
ing on floor. Inclosed small space with carpets, etc., to keep out wind.
Mr. Moss of Collington Island stopped with us for several hours and staye
d for dinner. Sky cleared up about 5 o'clock.
do not archive
Message 2
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| Subject: | Re: Push/pull tubes and rod ends |
I have the three NASA Aeronautic Structural Manuals in PDF format (one file
per volume) if anyone is interested. Send me an email (
ameetsavant@gmail.com) and I can send them to you. Thanks David for point
out such a great resource!
Ameet
On Sat, Oct 24, 2009 at 3:25 PM, David Paule <dpaule@frii.com> wrote:
> The equation you introduced is effective for the pull-out strength of the
> threads in a hole. The "(shear load)" you mentioned is the shear stress that
> the material can take, not the applied load.
>
> A good (in fact, one of the best) sources for structural analysis is free:
> http://euler9.tripod.com/analysis/asm.html
>
>
Message 3
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| Subject: | Re: Push/pull tubes and rod ends |
Perhaps they could be posted on the West Coast Pietenpol site....
David Paule
From: Ameet Savant
I have the three NASA Aeronautic Structural Manuals in PDF format
(one file per volume) if anyone is interested. Send me an email
(ameetsavant@gmail.com) and I can send them to you. Thanks David for
point out such a great resource!
Ameet
Message 4
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| Subject: | Re: Push/pull tubes and rod ends |
David, thank you, sir, for your input.- You offered a lot of solid use fu
ll info...thanks.- Allow me to read some of the other replies, then I'll
come back with some questions. (of course.)
Message 5
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| Subject: | Re: Push/pull tubes and rod ends |
Ryan, I appreciate your response. As you stated, we do not have flying plan
es yet, so the proof that a change is a benefit or not can't yet be verifie
d. Since, again as you stated, this plane has flown 80 years with cables.
- It works well and I don't think anyone has ever complained about the sy
stem. But maybe someone, either on this list or a friend of a person on thi
s list, or maybe knows someone, who knows someone who has, in fact installe
d tubes on a Piet. Maye they would have some real world data to share, so I
post to see if maybe someone has already "been there, done that".- Since
it appears that no one has, I don't think anyone can say one system is bet
ter or worse then the other..on this plane.- Bingelis and others state th
at the cable system is a good, solid system with many benefits...but no one
has done a cable -V- tube on comparison on THIS plane...so it seems.
-
Again, as I always revert to, I am no expert and I am finding my way in bui
lding AC. So I search, research and ask. I hope some one from the "been the
re done that" group will chime in and be able to give me some solid real wo
rld advice, but in this case it appears I may be the pioneer.- Basically,
I want to find out what size/material tube, (the lightest I can use) will
be a good replacement for the cables.- Once I have that, then I can see w
hat it would take to implement that system into the AC. It may prove to be
a bad idea, but I won't know until I get into it.- I am not going to both
er if it proves out that the only solid replacement for the cable system is
some big nasty 3/4" steel tube with 5 pound fittings on each end.- So, I
am back to my original quest, finding out what CAN be used safely.
Message 6
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| Subject: | Re: Push/pull tubes and rod ends |
Dick Navatril (sp?) has push-pull tubes to the elevator in the Rotec powered
Piet. He could probably give some insight into this. He did say there is a
"walking beam" aft of the rear seat to allow for shorter tubes and to change
angle of motion.
On Sun, Oct 25, 2009 at 11:45 AM, Michael Perez <speedbrake@sbcglobal.net>wrote:
> Ryan, I appreciate your response. As you stated, we do not have flying
> planes yet, so the proof that a change is a benefit or not can't yet be
> verified. Since, again as you stated, this plane has flown 80 years with
> cables. It works well and I don't think anyone has ever complained about
> the system. But maybe someone, either on this list or a friend of a person
> on this list, or maybe knows someone, who knows someone who has, in fact
> installed tubes on a Piet. Maye they would have some real world data to
> share, so I post to see if maybe someone has already "been there, done
> that". Since it appears that no one has, I don't think anyone can say one
> system is better or worse then the other..on this plane. Bingelis and
> others state that the cable system is a good, solid system with many
> benefits...but no one has done a cable -V- tube on comparison on THIS
> plane...so it seems.
>
> Again, as I always revert to, I am no expert and I am finding my way in
> building AC. So I search, research and ask. I hope some one from the "been
> there done that" group will chime in and be able to give me some solid real
> world advice, but in this case it appears I may be the pioneer. Basically,
> I want to find out what size/material tube, (the lightest I can use) will be
> a good replacement for the cables. Once I have that, then I can see what it
> would take to implement that system into the AC. It may prove to be a bad
> idea, but I won't know until I get into it. I am not going to bother if it
> proves out that the only solid replacement for the cable system is some big
> nasty 3/4" steel tube with 5 pound fittings on each end. So, I am back to
> my original quest, finding out what CAN be used safely.
>
> *
>
> *
>
>
--
"Politics is the art of looking for trouble, finding it whether it exists or
not, diagnosing it incorrectly, and applying the wrong remedy." --British
publisher and writer Ernest Benn (1875-1954)
Message 7
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| Subject: | Re: Push/pull tubes and rod ends |
Bill, if I may quote you:
-
"Regarding your request for a formula, the thing to keep in mind is that in
designing a mechanism like a push/pull system, you need to analyze each co
mponent and each connection in the system, and the loads that could be impo
sed on each component."-
-
I agree. Does anyone know these loads for each component currently used?-
I do not. I ASSUMED that a good place to start was with the cables.- Sin
ce the plans state 1/8" cable to drive both elevators, I started there with
the weaker cable, SS, rated at 1760 lbs.- Maybe I should find the weakes
t link in the current cable system and go from there. What is it? Is it the
attachment of the elevator horn to the elevator? Can this attachment take
a 1760 lb. load like the cable? Or how about a pulley...can-it and it att
aching brackets-withstand 1760?- Is 1760 overkill to begin with?
-
Is there a tube system that can be made as a substitute?- What about thes
e tube end fittings and attaching bell cranks,etc?- A simple-1/4-28 mal
e threaded rod end from McMaster Carr has a static radial load rating of-
2168 lbs.- If this was somehow attached to the 1760 lb. SS cable, no one
would have an issue with it...yes?- That led me to the tubes and the que
stion of what will strip the connection between the tube and this rod end?
What if the same bell cranks and horns were used, but connected to rod ends
and tubes?-However since you-no longer -need an attachment for both
an upper and lower cable, that same bell crank now weighs less because you
can "lop off" those unused attaching levers.-
-
I appreciate Jack's response, most of the time he does offer good facts. (a
long with some not always good opinion...)- But until someone has built a
nd flown a push/pull setup on a Piet., then no one can say for sure that on
e is better overall then another.- Frankly to outright say one is better
then the other, at this point, is unfounded.
-
"Cables can change direction with the addition of a simple pulley, where pu
sh/pull tubes will require bell cranks - which one do you think is heavier?
"-
-
Has anyone done a load analysis on this "simple pulley" as you stated shoul
d be done on all the components for the tube system?- Or do you just use
what everyone else uses and has been proven safe?- What about the attachm
ent of this pulley...load tested, or just following the crowd?-- No one
questions if the original modification was analyzed out the wazoo first. I
t seems most- believe that a change requires over the top analysis, testi
ng, etc. I believe it is SOMETIMES overkill and some simple common sense an
d homework will yield just as safe results.
-
A "bell crank" needs to be nothing more then a pivot point to allow the pus
h/pull tube to change direction. (see Gary Booth's and others pictures on t
he West Coast Piets site...I believe it is...)- If you could, you use the
same attaching bracket/hardware and just substitute this pivot in place of
the pulley...I don't know which one now weighs less.
-
"Jack's reply explained that the push/pull system will end up being heavier
than the cable system. So what IS the motivation to change to the push/pul
l system?"-
-
Again, I don't know how anyone can say this is definite without having a fl
ying example...it is a guess at best.
-
I appreciate most peoples responses, weather they agree with me or not, tha
t stick to the original question and respond with some good numbers, facts,
or references. Guessing, opinions and the like don't really help.- If it
can be proved that this push/pull is no good, I will not proceed to waste
my time.- I don't have the answers so I ask. Since it appears no Piet has
such a system, then I guess I will have to really figure out what is what
and decide what to do.
-
My original question still stands...what size material tube/ rod end will b
e a good replacement? I have gotten some replies that use language and form
ulas that are over my head. If you intelligent guys want to do the calculat
ions for me, I would be much obliged.
-
Thanks.
Message 8
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| Subject: | Re: Push/pull tubes and rod ends |
Thank you Pieti. Had I thought about the tube idea sooner, I would have bui
lt my wings to accommodate such a system. (THAT post would have gotten some
good replies...)
-
Message 9
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| Subject: | Re: Push/pull tubes and rod ends |
Thanks Bill. I would love to see pictures of his setup. I would guess he us
es the same setup for all controls?
-
I guess since this is my first plane build, I am ahead of the curve. By my
eighth, I will have redesigned the space shuttle.
Message 10
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| Subject: | Push/pull tubes and rod ends |
Gary,
-
my apologies to you and all on this list if I in anyway offended. I get eas
ily frustrated when, to me, I ask a simple question and get a lot of- "wh
y do you want to do that" replies. Or the ever popular, stop wasting time a
nd build to the prints."
-
I meant no disrespect to the late Mr. Pietenpol, you, members on this list,
the bible, God, etc.
-
I am humbled that there are people who would take the time to get on their
computer, load the list, read my question and try to help me. I need to kee
p in mind that no one is required to help in the first place.
Message 11
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| Subject: | Push/pull tubes and rod ends |
Thank you Jack.- My initial thought was to go with push/pull from the sti
ck, back to the original bell crank. From there, use cables. Then I started
to think about those cables and replacing them with push rods. That would
require a different bell crank design and horn design on the elevators. I w
as thinking of basically, using the bell crank design as is, but lop off th
e un-needed top levers. Same on the elevators...lop of the tops of the cont
rol horns. (in simple terms...I am sure some mods will be needed and not ju
st run these parts on a band saw.)- Then I mocked up my tail section usin
g clamps to hold it all and found that the angle from the elevator horns to
the bell crank levers were- not tube friendly...to much angle. So, then
I thought, I could move the bell crank back to the next pair of verticals o
n the fuselage, (which are closer together, so the bell crank tube is short
er and in theory weigh less and be stiffer because it is shorter.
(along with the lopped of top horns, this component is quite a bit lighter
then the original, but just a strong.)-- Then I could move the elevato
r horns closer towards the fuselage to have a more straight shot for the tu
bes.- My concern here is now the-horns are off towards the fuselage end
s of the elevators and the elevators may twist.- But, I could re-enforce
them not to twist, but that ads weight. But if the tube system over all is
lighter, then some added wood may not hurt much. (My general thought proces
s...I'm a nut!)
-
Whew!- So, I backed up and figured non of this matters if the tubes have
to be so large and heavy that is makes no sense. This is when I set out to
find the smallest, lightest tube/rod ends I can get. But in order to do tha
t, I must know what forces these tubes see and what loads they can handle i
n the various sizes/materials.
-
I then found the info. In the Bingelis books about the aluminum threaded tu
be, rod ends and a jamb nut. (no machined fittings, no rivets or bolts) Tha
t idea really appealed to me, but I still need to know what CAN be used for
THIS plane and ITS flight loads.- I hope to be able to give someone the
numbers they need to run these equations and see if what I am thinking can
be done. I can do it myself if I had a step by step procedure and some simp
le formulas. I have seen on the web a lot of equations, all of which seem t
o not be appropriate or too complicated. How hard is it to figure out when
an aluminum tube at a given size and its rod end fail? (pull apart?)- May
be it is harder to figure out then I thought.
-
Message 12
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| Subject: | Re: Push/pull tubes and rod ends |
I would like that "fly by wire" feel in my plane...
Message 13
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| Subject: | Re: Push/pull tubes and rod ends |
I-have some- 3/8" 6063 heavy wall aluminum tube. (hollow all the way th
rough) It has an ID of .145. (wall of .115) Yield strength of 15,000 PSI.
- I can drill this out and tap it for a 1/4-28" male threaded rod end. Ab
out 75%+ thread engaugement and I figure, for the calculations, .75" depth.
(no machined fitting...just thread the rod end into the tube with a jamb n
ut...as shown in the bingelis book.)- I have no idea, other then using th
e formula that my NASA engineer gave me, if this is a suitable replacement
for the 1760 lb. rated SS cable, or what tube/rod end would be suitable. Us
ing this example and that formula, I get an answer of over 2,000 lbs...bett
er then the 1760lb. rated-cable. Is this good? It it enough? Is the math
right?- I'm going crazy! (but enjoy the challange.)
Message 14
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| Subject: | Re: Push/pull tubes and rod ends |
"As you see, the control system doesn't need to be stronger than these forc
es applied to the control stick. It's a simple matter to go from there to t
he loads in any single part of the system."
-
How do you do this? I would like to know the loads on the individual tubes.
Message 15
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| Subject: | Re: Push/pull tubes and rod ends |
That equation you supplied is ONLY for the shear-out strength of the
threads. And that is only one of the things to check for.
It does not apply to the net tension strength of the tube, which you'll
find is considerably lower than that cable strength.
It does not apply to the Euler column strength of the tube, which is
dependent upon the length from pin to pin as well as that very low yield
strength.
However, with that thickness wall, it won't have the D/t crippling I
mentioned earlier.
There are probably other things to check for, but without an overall
design we don't know what those might be.
If you are trying to save weight, 6063 heavy wall tube won't get you
there. What's more, in general, 6063 is much weaker than most aircraft
metals.
It's time to draw out the control system to scale, apply the loads that
I found for you in FAR Part 23, and work them through to see what the
individual loads are in the various parts. Please bear in mind that you
need to consider yield and ultimate conditions here.
David Paule
----- Original Message -----
From: Michael Perez
To: pietenpol-list@matronics.com
Sent: Sunday, October 25, 2009 11:32 AM
Subject: Re: Pietenpol-List: Push/pull tubes and rod ends
I have some 3/8" 6063 heavy wall aluminum tube. (hollow all the
way through) It has an ID of .145. (wall of .115) Yield strength of
15,000 PSI. I can drill this out and tap it for a 1/4-28" male threaded
rod end. About 75%+ thread engaugement and I figure, for the
calculations, .75" depth. (no machined fitting...just thread the rod end
into the tube with a jamb nut...as shown in the bingelis book.) I have
no idea, other then using the formula that my NASA engineer gave me, if
this is a suitable replacement for the 1760 lb. rated SS cable, or what
tube/rod end would be suitable. Using this example and that formula, I
get an answer of over 2,000 lbs...better then the 1760lb. rated cable.
Is this good? It it enough? Is the math right? I'm going crazy! (but
enjoy the challange.)
Message 16
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| Subject: | Push/pull tubes and rod ends |
Without doing all the calculations myself I can't tell if your math is good
or not. But one thing to consider with small diameter pushrods is that
under compression loading they may buckle pretty easily, which could ruin
your whole day. Euler's (pronounced oilers) equation is used to determine
the critical load, beyond which the pushrod will "buckle", displacing the
middle of the pushrod sideways. This equation is:
Pe = p2EI
l 2
Where Pe is the critical load, beyond which any load will cause buckling, p
= 3.1415926., E is the modulus of elasticity (Young's Modulus) for the
material, I is the moment of inertia (for a circular annulus, I
p(do4-di4)/64 ), and l = the length of the pushrod. Once you have your tube
chosen, plug its numbers into Euler's equation and see what the buckling
load will be. If you think this is close to the load that the elevators can
put on the pushrod, then you may have to go to a larger diameter pushrod
tube.
If you use pushrods connected directly to the elevators, it would be best to
position the pushrods on top of the elevator, rather than underneath. The
reason for this is that you are more likely to put large loads into pulling
the nose of the airplane up than you will in pushing the nose down. If the
pushrods are on the bottom, any up-elevator inputs will be putting the
pushrod in compression, so if you prefer to have the pushrods under the
elevators, you will probably have to use larger diameter tubing.
Good luck,
Jack Phillips
NX899JP
Raleigh, NC
_____
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Michael
Perez
Sent: Sunday, October 25, 2009 1:33 PM
Subject: Re: Pietenpol-List: Push/pull tubes and rod ends
I have some 3/8" 6063 heavy wall aluminum tube. (hollow all the way
through) It has an ID of .145. (wall of .115) Yield strength of 15,000 PSI.
I can drill this out and tap it for a 1/4-28" male threaded rod end. About
75%+ thread engaugement and I figure, for the calculations, .75" depth. (no
machined fitting...just thread the rod end into the tube with a jamb
nut...as shown in the bingelis book.) I have no idea, other then using the
formula that my NASA engineer gave me, if this is a suitable replacement for
the 1760 lb. rated SS cable, or what tube/rod end would be suitable. Using
this example and that formula, I get an answer of over 2,000 lbs...better
then the 1760lb. rated cable. Is this good? It it enough? Is the math right?
I'm going crazy! (but enjoy the challange.)
Message 17
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| Subject: | Re: Push/pull tubes and rod ends |
Look, I don't mean to be critical at all, but it takes a design concept
with dimensions and angles, and then applying forces and finding
reactions to them. The techniques are in every basic high school physics
books in the chapter on statics. You'll probably need the same sorts of
equations as used in the weight and balance calculations, and some
general algebra. What you are dealing with here are levers and fulcrums
and cables.
As a modest suggestion, don't even begin to calculate the strength of
the pieces until you have a firm grasp of the loads in the design.
David Paule
From: Michael Perez
"As you see, the control system doesn't need to be stronger than
these forces applied to the control stick. It's a simple matter to go
from there to the loads in any single part of the system."
How do you do this? I would like to know the loads on the
individual tubes.
Message 18
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| Subject: | Re: Push/pull tubes and rod ends |
I can't recall the location, but it seems to me Mr. Wainfan addressed the
calculation of the airloads on a deflected control surface. This plus the
force required to overcome the hinge friction of the control surface should
be the total seen by the control circuit. As I remember, the load was a
function of the size of the surface(s), the amount of deflection, and the
Vne of the aircraft. It seems this would be a better way to determine the
actual forces seen in the control circuit rather than work from the old
cable figures. Chances are Mr. Pietenpol didn't do a destructive test on
the controls. He went with what worked for other installations in similar
aircraft. The actual forces seen might be considerable less than thought.
On Sun, Oct 25, 2009 at 1:54 PM, Michael Perez <speedbrake@sbcglobal.net>wrote:
> "As you see, the control system doesn't need to be stronger than these
> forces applied to the control stick. It's a simple matter to go from there
> to the loads in any single part of the system."
>
> How do you do this? I would like to know the loads on the individual tubes.
>
>
> *
>
> *
>
>
--
"Politics is the art of looking for trouble, finding it whether it exists or
not, diagnosing it incorrectly, and applying the wrong remedy." --British
publisher and writer Ernest Benn (1875-1954)
Message 19
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| Subject: | Re: Push/pull tubes and rod ends |
I should have noted, Mr. Wainfan writes the "Wind Tunnel" column in
"Kitplanes" magazine.
On Sun, Oct 25, 2009 at 3:36 PM, Lloyd Smith <lesmith240@gmail.com> wrote:
>
> I can't recall the location, but it seems to me Mr. Wainfan addressed the
> calculation of the airloads on a deflected control surface. This plus the
> force required to overcome the hinge friction of the control surface should
> be the total seen by the control circuit. As I remember, the load was a
> function of the size of the surface(s), the amount of deflection, and the
> Vne of the aircraft. It seems this would be a better way to determine the
> actual forces seen in the control circuit rather than work from the old
> cable figures. Chances are Mr. Pietenpol didn't do a destructive test on
> the controls. He went with what worked for other installations in similar
> aircraft. The actual forces seen might be considerable less than thought.
>
>
> On Sun, Oct 25, 2009 at 1:54 PM, Michael Perez <speedbrake@sbcglobal.net>wrote:
>
>> "As you see, the control system doesn't need to be stronger than these
>> forces applied to the control stick. It's a simple matter to go from there
>> to the loads in any single part of the system."
>>
>> How do you do this? I would like to know the loads on the individual
>> tubes.
>>
>>
>> *
>>
>> *
>>
>>
>
>
> --
> "Politics is the art of looking for trouble, finding it whether it exists
> or not, diagnosing it incorrectly, and applying the wrong remedy." --British
> publisher and writer Ernest Benn (1875-1954)
>
--
"Politics is the art of looking for trouble, finding it whether it exists or
not, diagnosing it incorrectly, and applying the wrong remedy." --British
publisher and writer Ernest Benn (1875-1954)
Message 20
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| Subject: | Re: Push/pull tubes and rod ends |
He also designed the "Facetmobile" but that's another story altogether.
What a weird looking airplane...
Do not archive
Wayne Bressler Jr.
Taildraggers, Inc.
taildraggersinc.com
Sent from the phone that made the Blackberry obsolete.
On Oct 25, 2009, at 3:39 PM, Lloyd Smith <lesmith240@gmail.com> wrote:
> I should have noted, Mr. Wainfan writes the "Wind Tunnel" column in
> "Kitplanes" magazine.
>
> On Sun, Oct 25, 2009 at 3:36 PM, Lloyd Smith <lesmith240@gmail.com>
> wrote:
>
> I can't recall the location, but it seems to me Mr. Wainfan
> addressed the calculation of the airloads on a deflected control
> surface. This plus the force required to overcome the hinge
> friction of the control surface should be the total seen by the
> control circuit. As I remember, the load was a function of the size
> of the surface(s), the amount of deflection, and the Vne of the
> aircraft. It seems this would be a better way to determine the
> actual forces seen in the control circuit rather than work from the
> old cable figures. Chances are Mr. Pietenpol didn't do a
> destructive test on the controls. He went with what worked for
> other installations in similar aircraft. The actual forces seen
> might be considerable less than thought.
>
>
> On Sun, Oct 25, 2009 at 1:54 PM, Michael Perez <speedbrake@sbcglobal.net
> > wrote:
> "As you see, the control system doesn't need to be stronger than
> these forces applied to the control stick. It's a simple matter to
> go from there to the loads in any single part of the system."
>
> How do you do this? I would like to know the loads on the individual
> tubes.
>
>
> " target="_blank">http://www.matronics.com/Navigator?Pietenpol-List
> tp://forums.matronics.com
> _blank">http://www.matronics.com/contribution
>
>
> --
> "Politics is the art of looking for trouble, finding it whether it
> exists or not, diagnosing it incorrectly, and applying the wrong
> remedy." --British publisher and writer Ernest Benn (1875-1954)
>
>
> --
> "Politics is the art of looking for trouble, finding it whether it
> exists or not, diagnosing it incorrectly, and applying the wrong
> remedy." --British publisher and writer Ernest Benn (1875-1954)
>
>
Message 21
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| Subject: | Re: Push/pull tubes and rod ends |
Can anyone supply more info on Mr. Wainfan and his calculations? The proces
s of surface area, speed and deflection to determine load seems to be more
relevant in a 80 mph Piet. then doing algebra, trig., calculus, etc. on eve
ry nut bolt bracket, rod in the system.- (Although, there is nothing wron
g with that...and a lot more precise/accurate.)
-
I have gotten some very, very good formulas/equations from the list that ar
e just to complicated and over my head to try and use. If this turns out to
be the only way to solve my issues, I will be installing cables. Still, I
would think I could at least figure out what tubes would work...even if the
y turn out to be too large and heavy to consider.
-
Thanks crew...some good stuff is now coming from this thread.
Message 22
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| Subject: | Re: Push/pull tubes and rod ends |
I'm sorry, but does anyone (everyone) else see the absurdity of this
kind of discussion/mathematics when we are talking about the building of
an all-wooden airplane that proved the soundness of its basic design 80
years ago???????
(not directed at you, Jack, I know you are responding)
Gene
do not archive
----- Original Message -----
From: Jack Phillips<mailto:pietflyr@bellsouth.net>
To: pietenpol-list@matronics.com<mailto:pietenpol-list@matronics.com>
Sent: Sunday, October 25, 2009 2:12 PM
Subject: RE: Pietenpol-List: Push/pull tubes and rod ends
Without doing all the calculations myself I can't tell if your math is
good or not. But one thing to consider with small diameter pushrods is
that under compression loading they may buckle pretty easily, which
could ruin your whole day. Euler's (pronounced oilers) equation is used
to determine the critical load, beyond which the pushrod will "buckle",
displacing the middle of the pushrod sideways. This equation is:
Pe = p2EI
l 2
Where Pe is the critical load, beyond which any load will cause
buckling, p = 3.1415926., E is the modulus of elasticity (Young's
Modulus) for the material, I is the moment of inertia (for a circular
annulus, I = p(do4-di4)/64 ), and l = the length of the pushrod.
Once you have your tube chosen, plug its numbers into Euler's equation
and see what the buckling load will be. If you think this is close to
the load that the elevators can put on the pushrod, then you may have to
go to a larger diameter pushrod tube.
If you use pushrods connected directly to the elevators, it would be
best to position the pushrods on top of the elevator, rather than
underneath. The reason for this is that you are more likely to put
large loads into pulling the nose of the airplane up than you will in
pushing the nose down. If the pushrods are on the bottom, any
up-elevator inputs will be putting the pushrod in compression, so if you
prefer to have the pushrods under the elevators, you will probably have
to use larger diameter tubing.
Good luck,
Jack Phillips
NX899JP
Raleigh, NC
-------------------------------------------------------------------------
-----
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Michael
Perez
Sent: Sunday, October 25, 2009 1:33 PM
To: pietenpol-list@matronics.com
Subject: Re: Pietenpol-List: Push/pull tubes and rod ends
I have some 3/8" 6063 heavy wall aluminum tube. (hollow all the
way through) It has an ID of .145. (wall of .115) Yield strength of
15,000 PSI. I can drill this out and tap it for a 1/4-28" male threaded
rod end. About 75%+ thread engaugement and I figure, for the
calculations, .75" depth. (no machined fitting...just thread the rod end
into the tube with a jamb nut...as shown in the bingelis book.) I have
no idea, other then using the formula that my NASA engineer gave me, if
this is a suitable replacement for the 1760 lb. rated SS cable, or what
tube/rod end would be suitable. Using this example and that formula, I
get an answer of over 2,000 lbs...better then the 1760lb. rated cable.
Is this good? It it enough? Is the math right? I'm going crazy! (but
enjoy the challange.)
http://www.matronics.com/Navigator?Pietenpol-Listhttp://forums.matronics.
comhttp://www.matronics.com/contribution
http://www.matronics.com/Navigator?Pietenpol-List<http://www.matronics.co
m/Navigator?Pietenpol-List>
http://www.matronics.com/contribution<http://www.matronics.com/contributi
on>
Message 23
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| Subject: | Re: Push/pull tubes and rod ends |
I went out and flew my daughter out to breakfast this morning before church. It
was fantastic, beautiful! I'm so glad I didn't have to think about how complicated
that extremely light and simple cable system could get!! Whew!
do not archive....save the space for all those great calculations! [Laughing]
Don Emch
NX899DE
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=269380#269380
Message 24
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| Subject: | Push/pull tubes and rod ends |
Jack, thanks for the equations, I will see if I understand the terms, and s
ee what I can do with them.
-
Good point on the elevator horns. (Something I would not have thought of an
d would never have considered had I not posted my original question.)
-
My pilot stick is currently made with the bottom of the stick bolted to the
torque tube. (the pivot point)- 6.5" (6.25?") above that, (print dimensi
on), I welded in two tangs for my rod end to bolt between. (this puts the r
od end and tube on center with the stick and not off to one side. It also r
elieves the twist that a side mounted rod end may put on the stick..if that
matters...) With the rod end between the tangs, I do not need to worry abo
ut it coming off if the rod end bearing fails. (No need for extra large was
hers.)
-
Anyhoo, if I pull the stick back, it pushes the rod back and that linear mo
tion would then have to go to a horn under the elevator to move it in the p
roper direction. This would also give the plane, while on the ground, a cle
aner look with no cables/horns on top of the elevators, as well as no cable
rub on top.- To get the horn on top of the elevator, I would need that b
ell crank to have a top and bottom lever, (as drawn on the plans) then plac
e the rod ends accordingly to get the proper deflection... easy to do.- I
like the idea of having at least some "pull" rather then all "push" as you
suggested.- I could introduce a second bell crank, say right behind the
pilot seat, low, so the "push" tube from the stick can be short. From there
run to the original bell crank, now having the majority of tubes in the "p
ull" arena...in theory.- (that adds weight though.) The other thing I lik
e about this setup, is with the various pivots, idler arms, bell cranks,
etc., one can play with the lengths and locations of the levers and attach
ing points of the rod ends to change throw travel on the stick, deflection
angle of the control surfaces and mechanical leverage. (Trying for that fly
by wire feel!) Good stuff...hope it all works out. If not, I know the cabl
e system works and that is not a bad thing to fall back on.
-
-
---
Message 25
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| Subject: | Re: Push/pull tubes and rod ends |
Sorry to bother you with a discussion that isn't in the realm of "cookie
cutter" airplanes. Now I know why Bill Rewey shows no interest in the
list. I suppose lurk mode is where I belong. I'll absorb what knowledge
there is to be had here and then winnow the chaff from the wheat, without
input, of course!
On Sun, Oct 25, 2009 at 6:39 PM, Gene Rambo <generambo@msn.com> wrote:
> I'm sorry, but does anyone (everyone) else see the absurdity of this kind
> of discussion/mathematics when we are talking about the building of an
> all-wooden airplane that proved the soundness of its basic design 80 years
> ago???????
>
>
> (not directed at you, Jack, I know you are responding)
>
> Gene
> do not archive
>
>
> ----- Original Message -----
>
> *From:* Jack Phillips <pietflyr@bellsouth.net>
> *To:* pietenpol-list@matronics.com
> *Sent:* Sunday, October 25, 2009 2:12 PM
> *Subject:* RE: Pietenpol-List: Push/pull tubes and rod ends
>
> Without doing all the calculations myself I can't tell if your math is
> good or not. But one thing to consider with small diameter pushrods is that
> under compression loading they may buckle pretty easily, which could ruin
> your whole day. Euler's (pronounced oilers) equation is used to determine
> the critical load, beyond which the pushrod will "buckle", displacing the
> middle of the pushrod sideways. This equation is:
>
>
> Pe = *p**2**EI*
>
> l 2
>
> Where Pe is the critical load, beyond which any load will cause buckling,
> p = 3.1415926., E is the modulus of elasticity (Young's Modulus) for the
> material, I is the moment of inertia (for a circular annulus, I = p(do4-di
> 4)/64 ), and l = the length of the pushrod. Once you have your tube
> chosen, plug its numbers into Euler's equation and see what the buckling
> load will be. If you think this is close to the load that the elevators can
> put on the pushrod, then you may have to go to a larger diameter pushrod
> tube.
>
>
> If you use pushrods connected directly to the elevators, it would be best
> to position the pushrods on top of the elevator, rather than underneath.
> The reason for this is that you are more likely to put large loads into
> pulling the nose of the airplane up than you will in pushing the nose down.
> If the pushrods are on the bottom, any up-elevator inputs will be putting
> the pushrod in compression, so if you prefer to have the pushrods under the
> elevators, you will probably have to use larger diameter tubing.
>
>
> Good luck,
>
>
> Jack Phillips
>
> NX899JP
>
> Raleigh, NC
> ------------------------------
>
> *From:* owner-pietenpol-list-server@matronics.com [mailto:
> owner-pietenpol-list-server@matronics.com] *On Behalf Of *Michael Perez
> *Sent:* Sunday, October 25, 2009 1:33 PM
> *To:* pietenpol-list@matronics.com
> *Subject:* Re: Pietenpol-List: Push/pull tubes and rod ends
>
>
> I have some 3/8" 6063 heavy wall aluminum tube. (hollow all the way
> through) It has an ID of .145. (wall of .115) Yield strength of 15,000 PSI.
> I can drill this out and tap it for a 1/4-28" male threaded rod end. About
> 75%+ thread engaugement and I figure, for the calculations, .75" depth. (no
> machined fitting...just thread the rod end into the tube with a jamb
> nut...as shown in the bingelis book.) I have no idea, other then using the
> formula that my NASA engineer gave me, if this is a suitable replacement for
> the 1760 lb. rated SS cable, or what tube/rod end would be suitable. Using
> this example and that formula, I get an answer of over 2,000 lbs...better
> then the 1760lb. rated cable. Is this good? It it enough? Is the math
> right? I'm going crazy! (but enjoy the challange.)
>
> * *
>
> * *
>
> **
>
> **
>
> **
>
> *http://www.matronics.com/Navigator?Pietenpol-List*
>
> **
>
> **
>
> *http://forums.matronics.com*
>
> **
>
> **
>
> *http://www.matronics.com/contribution*
>
> * *
>
> *
>
> title=http://www.matronics.com/Navigator?Pietenpol-List href="http://www.matronics.com/Navigator?Pietenpol-List">http://www.matronics.com/Navigator?Pietenpol-List
>
> href="http://forums.matronics.com">http://forums.matronics.com
> href="http://www.matronics.com/contribution">http://www.matronics.com/c
> *
>
> *
>
>
> *
>
>
--
"Politics is the art of looking for trouble, finding it whether it exists or
not, diagnosing it incorrectly, and applying the wrong remedy." --British
publisher and writer Ernest Benn (1875-1954)
Message 26
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|
| Subject: | Re: Push/pull tubes and rod ends |
Gene,
You're not the only one. To me, this isn't really the kind of change
that's worth doing. It doesn't seem to me that it would improve
anything. Rather, in the process of making this change, an
overwhelming number of critical components will have to be modified
and/or be re-engineered.
If there was a deficiency in the original design, I could very easily
see the need to make changes. But this, to me, is too in depth of a
change for no clear reason.
Some things are simple, like reclining the seat back, or extending the
cabanes. But this is just too much work for no discernable gain.
There's a valid reason for sticking to the plans. Every change
requires additional time to conceive, engineer, analyze, and
implement. If the plans were followed, and changes were kept to
simple things, airplanes would be finished much faster, and fewer
projects would go un-finished.
One if my biggest concerns about these large changes is what happens
when you try to sell the airplane. Personally, I would avoid
purchasing any airplane, flying or project, which had been modified
this extensively without the proper engineering being done.
Sorry to be another voice sounding against the push-pull idea.
Do not archive.
Wayne Bressler Jr.
Taildraggers, Inc.
taildraggersinc.com
Sent from the phone that made the Blackberry obsolete.
On Oct 25, 2009, at 6:39 PM, "Gene Rambo" <generambo@msn.com> wrote:
> I'm sorry, but does anyone (everyone) else see the absurdity of this
> kind of discussion/mathematics when we are talking about the
> building of an all-wooden airplane that proved the soundness of its
> basic design 80 years ago???????
>
>
> (not directed at you, Jack, I know you are responding)
>
> Gene
> do not archive
>
>
> ----- Original Message -----
> From: Jack Phillips
> To: pietenpol-list@matronics.com
> Sent: Sunday, October 25, 2009 2:12 PM
> Subject: RE: Pietenpol-List: Push/pull tubes and rod ends
>
> Without doing all the calculations myself I can't tell if your math
> is good or not. But one thing to consider with small diameter
> pushrods is that under compression loading they may buckle pretty
> easily, which could ruin your whole day. Euler's (pronounced
> oilers) equation is used to determine the critical load, beyond
> which the pushrod will "buckle", displacing the middle of the
> pushrod sideways. This equation is:
>
> Pe = p2EI
> l 2
> Where Pe is the critical load, beyond which any load will cause
> buckling, p = 3.1415926., E is the modulus of elasticity (Young's
> Modulus) for the material, I is the moment of inertia (for a
> circular annulus, I = p(do4-di4)/64 ), and l = the length of the
> pushrod. Once you have your tube chosen, plug its numbers into
> Euler's equation and see what the buckling load will be. If you
> think this is close to the load that the elevators can put on the
> pushrod, then you may have to go to a larger diameter pushrod tube.
>
> If you use pushrods connected directly to the elevators, it would be
> best to position the pushrods on top of the elevator, rather than
> underneath. The reason for this is that you are more likely to put
> large loads into pulling the nose of the airplane up than you will
> in pushing the nose down. If the pushrods are on the bottom, any up-
> elevator inputs will be putting the pushrod in compression, so if
> you prefer to have the pushrods under the elevators, you will
> probably have to use larger diameter tubing.
>
> Good luck,
>
> Jack Phillips
> NX899JP
> Raleigh, NC
> From: owner-pietenpol-list-server@matronics.com [mailto:owner-
> pietenpol-list-server@matronics.com] On Behalf Of Michael Perez
> Sent: Sunday, October 25, 2009 1:33 PM
> To: pietenpol-list@matronics.com
> Subject: Re: Pietenpol-List: Push/pull tubes and rod ends
>
>
> I have some 3/8" 6063 heavy wall aluminum tube. (hollow all the way
> through) It has an ID of .145. (wall of .115) Yield strength of
> 15,000 PSI. I can drill this out and tap it for a 1/4-28" male
> threaded rod end. About 75%+ thread engaugement and I figure, for
> the calculations, .75" depth. (no machined fitting...just thread the
> rod end into the tube with a jamb nut...as shown in the bingelis
> book.) I have no idea, other then using the formula that my NASA
> engineer gave me, if this is a suitable replacement for the 1760 lb.
> rated SS cable, or what tube/rod end would be suitable. Using this
> example and that formula, I get an answer of over 2,000 lbs...better
> then the 1760lb. rated cable. Is this good? It it enough? Is the
> math right? I'm going crazy! (but enjoy the challange.)
>
>
> http://www.matronics.com/Navigator?Pietenpol-List
> http://forums.matronics.com
> http://www.matronics.com/contribution
>
>
> title=http://www.matronics.com/Navigator?Pietenpol-List href="http://www.matronics.com/Navigator?Pietenpol-List
> ">http://www.matronics.com/Navigator?Pietenpol-List
> href="http://forums.matronics.com">http://forums.matronics.com
> href="http://www.matronics.com/contribution">http://
> www.matronics.com/c
>
>
Message 27
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| Subject: | Re: Push/pull tubes and rod ends |
Right, like there aren't ANY threads in the archives that are lame, off top
ic, boring, or just plan ol' stupid.- Everything in there must be all goo
d usefull information with no useless responses from people who have all th
e answers.
Message 28
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| Subject: | Re: Push/pull tubes and rod ends -- Chaffinch |
Now I don't want to start anything about a guy who has built eight Piets,
but I found very strange his position of the "Chaffinch's" jury struts, very near
the end of the lift struts. My thought has been that you want to place the
jury strut near, but not at the middle of the lift strut. The "not at the middle"
has to do with avoiding the harmonic cited in other posts on our message
board. Near the middle is to optimize the reduction of buckling, as also previously
discussed.
His other changes seem a matter of taste, esp. since he claims no "Pietenpol"
in the plane's name.
Tim in central TX
-----Original Message-----
>From: Pieti Lowell <Lowellcfrank@yahoo.com>
>Sent: Oct 24, 2009 9:39 PM
>To: pietenpol-list@matronics.com
>Subject: Pietenpol-List: Re: Push/pull tubes and rod ends
>
>
>You might also note that the airfoil is a 4412., shortened 2 Ft and with an 85
HP Cont it could cruse 105 plus. The center- section is 3 Ft. wide.
> Pieti Lowell
>Bill Church wrote:
>> Here's a link to some photos of the Challis Chaffinch that Lowell referred to.
>>
>> http://www.shhas.co.uk/GALLERY_files/photos/Challis%20Chaffinch%20Test%20Flight/image_14.html
>>
>> The aileron push/pull tube can be seen on the right side. Interesting to note
that it is officially not a Pietenpol Air Camper - it is a Challis Chaffinch.
The builder made a number of visible changes - including the shape of the empennage,
a widened center-section (although the fuel tank appears to be in the
fuselage). Undoubtedly there are other changes that are not visible. I would
think that any builder building their EIGHTH copy of a plane might have a few
ideas about ways they would like to change things.
>>
>> Bill C.
>
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| Subject: | Re: Push/pull tubes and rod ends |
If you were using push-pull tubes you probably would have gotten to
breakfast much faster however ;)
rh
On Sun, Oct 25, 2009 at 6:57 PM, Don Emch <EmchAir@aol.com> wrote:
>
> I went out and flew my daughter out to breakfast this morning before
> church. It was fantastic, beautiful! I'm so glad I didn't have to think
> about how complicated that extremely light and simple cable system could
> get!! Whew!
>
> do not archive....save the space for all those great calculations!
> [Laughing]
>
> Don Emch
> NX899DE
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=269380#269380
>
>
--
Rick Holland
Castle Rock, Colorado
"Logic is a wreath of pretty flowers, that smell bad"
Message 30
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| Subject: | Re: Push/pull tubes and rod ends |
I see it exactly the opposite of you. The main reason to consider (I'm not saying
build) deviating from the plans is to honor the B. Pietenpol spirit of always
build safer and better flying aircraft. There is no need to cure the deficiency
in the design, reason enough is to make B.P. happy in heavens, as he is known
not to build two exactly the same aircraft and to be as far from "purist"
as he can be. After all he abandoned one of the most significant marks of his
design (Ford engine) as soon as he got a chance to do it. I deeply beleive if
he can see someone building Piet with Ford enigne in 2009 he would think for
him self "Oh, no, another ..... building by the plans".
The amount of hate in the form "Oh, I just flew my Piet, and you morons talk about
something better instead to build by the plans like me" is getting quite disturbing.
There is no wonder people got annoyed. There is no single thread in
which some deviation from the plans is mentioned that is not rapidly shut with
flood of "Why, why, why, when this design confirmed it self for 80 years?" messegaes.
To honor B.P, is there any other reason needed?
Regards,
and please don't mind the rough tone, I got excited how this thread is cut of,
and I am very interested in building with pushrods for several reasons,
Ivan Todorovic
[quote="wayne(at)taildraggersinc."]Gene,
You're not the only one. To me, this isn't really the kind of change that's worth
doing. It doesn't seem to me that it would improve anything. Rather, in
the process of making this change, an overwhelming number of critical components
will have to be modified and/or be re-engineered.
If there was a deficiency in the original design, I could very easily see the need
to make changes. But this, to me, is too in depth of a change for no clear
reason.
Some things are simple, like reclining the seat back, or extending the cabanes.
But this is just too much work for no discernable gain.
There's a valid reason for sticking to the plans. Every change requires additional
time to conceive, engineer, analyze, and implement. If the plans were followed,
and changes were kept to simple things, airplanes would be finished much
faster, and fewer projects would go un-finished.
One if my biggest concerns about these large changes is what happens when you try
to sell the airplane. Personally, I would avoid purchasing any airplane, flying
or project, which had been modified this extensively without the proper
engineering being done.
Sorry to be another voice sounding against the push-pull idea.
Do not archive.
Wayne Bressler Jr.Taildraggers, Inc.
taildraggersinc.com (http://taildraggersinc.com)
Sent from the phone that made the Blackberry obsolete.
On Oct 25, 2009, at 6:39 PM, "Gene Rambo" wrote:
> st1:*{behavior:url(#default#ieooui) } I'm sorry, but does anyone (everyone)
else see the absurdity of this kind of discussion/mathematics when
we are talking about the building of an all-wooden airplane that proved the soundness
of its basic design 80 years ago???????
>
>
> (not directed at you, Jack, I know you are responding)
>
> Gene
> do not archive
>
>
> ---
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=269392#269392
Message 31
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| Subject: | Re: Push/pull tubes and rod ends |
Oh, yeah...
In fact I'm a bit astonished that anyone would want to attempt to make
such modifications when they don't have the slightest knowledge of it.
As my earlier postings and Jack's suggested, there's a lot to understand
and comprehend if you are going to do things like this. And with the
design being so clearly acceptable as-is, to me it implies that the main
reason for this isn't to change the aircraft (I hope!) but to learn
about the mechanics of it.
I hope I'm not stepping on anyone's toes here....
David Paule
do not archive
----- Original Message -----
From: Gene Rambo
To: pietenpol-list@matronics.com
Sent: Sunday, October 25, 2009 4:39 PM
Subject: Re: Pietenpol-List: Push/pull tubes and rod ends
I'm sorry, but does anyone (everyone) else see the absurdity of this
kind of discussion/mathematics when we are talking about the building of
an all-wooden airplane that proved the soundness of its basic design 80
years ago???????
(not directed at you, Jack, I know you are responding)
Gene
do not archive
----- Original Message -----
From: Jack Phillips
To: pietenpol-list@matronics.com
Sent: Sunday, October 25, 2009 2:12 PM
Subject: RE: Pietenpol-List: Push/pull tubes and rod ends
Without doing all the calculations myself I can't tell if your math
is good or not. But one thing to consider with small diameter pushrods
is that under compression loading they may buckle pretty easily, which
could ruin your whole day. Euler's (pronounced oilers) equation is used
to determine the critical load, beyond which the pushrod will "buckle",
displacing the middle of the pushrod sideways. This equation is:
Pe = p2EI
l 2
Where Pe is the critical load, beyond which any load will cause
buckling, p = 3.1415926., E is the modulus of elasticity (Young's
Modulus) for the material, I is the moment of inertia (for a circular
annulus, I = p(do4-di4)/64 ), and l = the length of the pushrod.
Once you have your tube chosen, plug its numbers into Euler's equation
and see what the buckling load will be. If you think this is close to
the load that the elevators can put on the pushrod, then you may have to
go to a larger diameter pushrod tube.
If you use pushrods connected directly to the elevators, it would be
best to position the pushrods on top of the elevator, rather than
underneath. The reason for this is that you are more likely to put
large loads into pulling the nose of the airplane up than you will in
pushing the nose down. If the pushrods are on the bottom, any
up-elevator inputs will be putting the pushrod in compression, so if you
prefer to have the pushrods under the elevators, you will probably have
to use larger diameter tubing.
Good luck,
Jack Phillips
NX899JP
Raleigh, NC
-------------------------------------------------------------------------
---
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Michael
Perez
Sent: Sunday, October 25, 2009 1:33 PM
To: pietenpol-list@matronics.com
Subject: Re: Pietenpol-List: Push/pull tubes and rod ends
I have some 3/8" 6063 heavy wall aluminum tube. (hollow all
the way through) It has an ID of .145. (wall of .115) Yield strength of
15,000 PSI. I can drill this out and tap it for a 1/4-28" male threaded
rod end. About 75%+ thread engaugement and I figure, for the
calculations, .75" depth. (no machined fitting...just thread the rod end
into the tube with a jamb nut...as shown in the bingelis book.) I have
no idea, other then using the formula that my NASA engineer gave me, if
this is a suitable replacement for the 1760 lb. rated SS cable, or what
tube/rod end would be suitable. Using this example and that formula, I
get an answer of over 2,000 lbs...better then the 1760lb. rated cable.
Is this good? It it enough? Is the math right? I'm going crazy! (but
enjoy the challange.)
http://www.matronics.com/Navigator?Pietenpol-Listhttp://forums.matronics.
comhttp://www.matronics.com/contribution
title=http://www.matronics.com/Navigator?Pietenpol-List
href="http://www.matronics.com/Navigator?Pietenpol-List">http://www.mat
ronics.com/Navigator?Pietenpol-List
href="http://forums.matronics.com">http://forums.matronics.com
href="http://www.matronics.com/contribution">http://www.matronics.com/c
Message 32
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| Subject: | Re: Push/pull tubes and rod ends |
Take it from me.... starting with the government's forces at the control
stick and working out from there is the easy way to do the job.
Make it easy on yourself and install the controls exactly as the plans
describe them.
David Paule
Can anyone supply more info on Mr. Wainfan and his calculations? The
process of surface area, speed and deflection to determine load seems to
be more relevant in a 80 mph Piet. then doing algebra, trig., calculus,
etc. on every nut bolt bracket, rod in the system. (Although, there is
nothing wrong with that...and a lot more precise/accurate.)I have gotten
some very, very good formulas/equations from the list that are just to
complicated and over my head to try and use. If this turns out to be the
only way to solve my issues, I will be installing cables. Still, I would
think I could at least figure out what tubes would work...even if they
turn out to be too large and heavy to consider.Thanks crew...some good
stuff is now coming from this thread.
Message 33
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| Subject: | Re: Push/pull tubes and rod ends |
On Sun, Oct 25, 2009 at 8:01 PM, David Paule <dpaule@frii.com> wrote:
> starting with the government's forces at the control stick
>
????
--
"Politics is the art of looking for trouble, finding it whether it exists or
not, diagnosing it incorrectly, and applying the wrong remedy." --British
publisher and writer Ernest Benn (1875-1954)
Message 34
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| Subject: | Re: Push/pull tubes and rod ends |
[quote="dpaule(at)frii.com"]Take it from me.... starting with the government's
forces at the control stick and working out from there is the easy way to do
the job.
Make it easy on yourself and install the controls exactly as the plans describe
them.
David Paule
[quote]
OK, why would I (for instance, and anyone else) take it from you, when the authority
like Pieti Lowell says on this very thread says the opposite: his personal
plane had the push/pull tube AND flew perfectly AND safe for many years? Have
you got any better argument?
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=269402#269402
Message 35
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| Subject: | Re: Push/pull tubes and rod ends |
I take what I want from this forum and leave the rest, I read what
I feel I need and hit the delete key on the rest. None of you
will know how much I respect you and you won't know if
I don't like you for I take what I need and leave the rest,
My plane will some day be finnished and by then I will
made friends with some of you and have forgotten the rest.
Russell Ray
270 300 9725
On Sun, Oct 25, 2009 at 7:54 PM, ivan.todorovic <tosha@sezampro.rs> wrote:
>
> I see it exactly the opposite of you. The main reason to consider (I'm not
> saying build) deviating from the plans is to honor the B. Pietenpol spirit
> of always build safer and better flying aircraft. There is no need to cure
> the deficiency in the design, reason enough is to make B.P. happy in
> heavens, as he is known not to build two exactly the same aircraft and to be
> as far from "purist" as he can be. After all he abandoned one of the most
> significant marks of his design (Ford engine) as soon as he got a chance to
> do it. I deeply beleive if he can see someone building Piet with Ford enigne
> in 2009 he would think for him self "Oh, no, another ..... building by the
> plans".
>
> The amount of hate in the form "Oh, I just flew my Piet, and you morons
> talk about something better instead to build by the plans like me" is
> getting quite disturbing. There is no wonder people got annoyed. There is no
> single thread in which some deviation from the plans is mentioned that is
> not rapidly shut with flood of "Why, why, why, when this design confirmed it
> self for 80 years?" messegaes. To honor B.P, is there any other reason
> needed?
>
> Regards,
> and please don't mind the rough tone, I got excited how this thread is cut
> of, and I am very interested in building with pushrods for several reasons,
> Ivan Todorovic
>
>
> [quote="wayne(at)taildraggersinc."]Gene,
>
>
> You're not the only one. To me, this isn't really the kind of change
> that's worth doing. It doesn't seem to me that it would improve anything.
> Rather, in the process of making this change, an overwhelming number of
> critical components will have to be modified and/or be re-engineered.
>
>
> If there was a deficiency in the original design, I could very easily see
> the need to make changes. But this, to me, is too in depth of a change for
> no clear reason.
>
>
> Some things are simple, like reclining the seat back, or extending the
> cabanes. But this is just too much work for no discernable gain.
>
>
> There's a valid reason for sticking to the plans. Every change requires
> additional time to conceive, engineer, analyze, and implement. If the plans
> were followed, and changes were kept to simple things, airplanes would be
> finished much faster, and fewer projects would go un-finished.
>
>
> One if my biggest concerns about these large changes is what happens when
> you try to sell the airplane. Personally, I would avoid purchasing any
> airplane, flying or project, which had been modified this extensively
> without the proper engineering being done.
>
>
> Sorry to be another voice sounding against the push-pull idea.
>
>
> Do not archive.
>
> Wayne Bressler Jr.Taildraggers, Inc.
> taildraggersinc.com (http://taildraggersinc.com)
>
>
> Sent from the phone that made the Blackberry obsolete.
>
>
> On Oct 25, 2009, at 6:39 PM, "Gene Rambo" wrote:
>
>
> > st1:*{behavior:url(#default#ieooui) } I'm sorry, but does
> anyone (everyone) else see the absurdity of this kind of
> discussion/mathematics when we are talking about the building of an
> all-wooden airplane that proved the soundness of its basic design 80 years
> ago???????
> >
> >
> > (not directed at you, Jack, I know you are responding)
> >
> > Gene
> > do not archive
> >
> >
> > ---
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=269392#269392
>
>
Message 36
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| Subject: | Re: Push/pull tubes and rod ends |
This will be my last comment on this thread.
First off, Michael, if you follow through with a push/pull system, you will not
be the first. It has been done before. Refer to the following link for a photo
of a GN-1 with such a system:
http://www.westcoastpiet.com/images/Pete%20Smith/Brodhead__20070720_028.JPG
Note that the control tube for the rudder is not tiny. The control tube for the
elevators is likely buried inside the fuselage, and the elevators are most likely
built of steel tube, in order to be able to transfer the torque adequately.
My thoughts are that if this system was an improvement, we would see more flying
examples of it. Just because it has been done does not mean it's a good
idea.
Secondly, all of the "opinions" that have been expressed regarding the negative
aspects of attempting to use a push/pull system on this aircraft have been based
on sound engineering principles. The reason why nobody has offered data to
prove your theory wrong is that your "system" has no data behind it. There are
no dimensions to work with. Not even a basic sketch. There are often a thousand
ways to achieve the same basic goal, with some being better than others, but
no one being the "right" way. For instance, as one reply stated, the proper
size for the tubes is dependent on the length, in reference to buckling strength.
Thirdly, unless someone out there decides that they want to do all the calculations
for you, you will eventually have to deal with all of that "language and
formulas" that, as you put it, are "over your head". As I said before, it's not
simple. Once the routing of the system is determined (including all pivot points),
you will need to determine the loads that will be imposed on the system
(plus an appropriate factor of safety). From there you will be able to determine
the loads that will be carried by each component, and based on those numbers,
you will determine the sizes of each component. (There's a reason why it takes
four years of university to obtain a degree in Engineering).
And finally, all of the above is my OPINION. But my opinion is based on more than
twenty years experience working as a Professional Engineer. Take it or leave
it.
Bill C.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=269403#269403
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| Subject: | Re: Push/pull tubes and rod ends |
No politics at all here, folks, move along.
Just to recap (yet again), I'd previously linked to the FAA's rules for
certified aircraft, and particularly to where they specified what the
maximum loads at the control stick could be. Then I said to start with
those, and figure out the loads as they worked their way to the control
surface. This is the easy way to do it, if you want to do it at all.
Regardless of how you feel about governmental actions in general, in
this instance, here, the specific regulations are sensible and to the
point. It's kind of heartening to know that once in a while the
government got it right.
David Paule
--
"Politics is the art of looking for trouble, finding it whether it
exists or not, diagnosing it incorrectly, and applying the wrong
remedy." --British publisher and writer Ernest Benn (1875-1954)
Message 38
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| Subject: | Re: Push/pull tubes and rod ends |
Because the gentleman who wants to learn how to do this basic engineering is
finding it difficult to begin the problem, and is getting overwhelmed with
the information that's been presented.
Obviously a push-pull system can be designed and if done properly, it will
work well. That's not the issue. Nor is it an issue whether a redesigned
control system should be made; that's a matter of choice. There are pros and
cons to any variation to the plans, and the plans design is an excellent
"control" to test the goodness of any particular redesign.
It can be designed if someone wants to take the effort to do so, although
it's not necessary, and they might find it just as enlightening as actually
building the aircraft. My motive for writing has been to facilitate his
learning and to point out appropriate information which he might find of
use. In fact, which anyone who wants to embark on an aircraft design
project, might find of use.
Here, though, it was becoming apparant that the resources of this List would
not extend to providing the requestor with sufficient capability to actually
make an engineering judgement of his design, which has been his expressed
goal. In light of that, it was proper to advise him to built it stock.
David Paule
========================
>
> [quote="dpaule(at)frii.com"]Take it from me.... starting with the
> government's forces at the control stick and working out from there is
> the easy way to do the job.
>
> Make it easy on yourself and install the controls exactly as the plans
> describe them.
>
> David Paule
> [quote]
>
> OK, why would I (for instance, and anyone else) take it from you, when the
> authority like Pieti Lowell says on this very thread says the opposite:
> his personal plane had the push/pull tube AND flew perfectly AND safe for
> many years? Have you got any better argument?
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=269402#269402
>
>
>
Message 39
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| Subject: | Re: Push/pull tubes and rod ends |
We don't need no steenkin' Part 23 here! :-)
On Sun, Oct 25, 2009 at 8:41 PM, David Paule <dpaule@frii.com> wrote:
> No politics at all here, folks, move along.
>
> Just to recap (yet again), I'd previously linked to the FAA's rules for
> certified aircraft, and particularly to where they specified what the
> maximum loads at the control stick could be. Then I said to start with
> those, and figure out the loads as they worked their way to the control
> surface. This is the easy way to do it, if you want to do it at all.
>
> Regardless of how you feel about governmental actions in general, in this
> instance, here, the specific regulations are sensible and to the point. It's
> kind of heartening to know that once in a while the government got it right.
>
> David Paule
>
>
> --
> "Politics is the art of looking for trouble, finding it whether it exists
> or not, diagnosing it incorrectly, and applying the wrong remedy." --British
> publisher and writer Ernest Benn (1875-1954)
>
> *
>
>
> *
>
>
--
"Politics is the art of looking for trouble, finding it whether it exists or
not, diagnosing it incorrectly, and applying the wrong remedy." --British
publisher and writer Ernest Benn (1875-1954)
Message 40
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| Subject: | Re: Push/pull tubes and rod ends |
dpaule(at)frii.com wrote:
> Here, though, it was becoming apparant that the resources of this List would
> not extend to providing the requestor with sufficient capability to actually
> make an engineering judgement of his design, which has been his expressed
> goal. In light of that, it was proper to advise him to built it stock.
>
> David Paule
>
He didn't get as far as discussing the tube diameter and wall thickness before
he was flooded with "don't do it" messages, let alone more complicated meters.
Requester had no chance.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=269413#269413
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| Subject: | Re: Push/pull tubes and rod ends |
Or Part 25...
On Sun, Oct 25, 2009 at 9:07 PM, Lloyd Smith <lesmith240@gmail.com> wrote:
> We don't need no steenkin' Part 23 here! :-)
>
>
> On Sun, Oct 25, 2009 at 8:41 PM, David Paule <dpaule@frii.com> wrote:
>
>> No politics at all here, folks, move along.
>>
>> Just to recap (yet again), I'd previously linked to the FAA's rules for
>> certified aircraft, and particularly to where they specified what the
>> maximum loads at the control stick could be. Then I said to start with
>> those, and figure out the loads as they worked their way to the control
>> surface. This is the easy way to do it, if you want to do it at all.
>>
>> Regardless of how you feel about governmental actions in general, in this
>> instance, here, the specific regulations are sensible and to the point. It's
>> kind of heartening to know that once in a while the government got it right.
>>
>> David Paule
>>
>>
>>
>>
>>
>>
>>
>>
>> --
>> "Politics is the art of looking for trouble, finding it whether it exists
>> or not, diagnosing it incorrectly, and applying the wrong remedy." --British
>> publisher and writer Ernest Benn (1875-1954)
>>
>> *
>>
>>
>>
>> *
>>
>>
>
>
> --
> "Politics is the art of looking for trouble, finding it whether it exists
> or not, diagnosing it incorrectly, and applying the wrong remedy." --British
> publisher and writer Ernest Benn (1875-1954)
>
--
"Politics is the art of looking for trouble, finding it whether it exists or
not, diagnosing it incorrectly, and applying the wrong remedy." --British
publisher and writer Ernest Benn (1875-1954)
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| Subject: | And the real work begins... |
Well, after futzing around for a few weeks with my 613.5 rib jib jig,
I have finally invested in some rough cut poplar, and turned it into
little sticks yesterday. I went over to my friend Ray's house, and we
spent the day cutting about 15 or so board feet of wood into 109 6
foot long sticks 1/4" x 1/2". We had a lot of fun, and I am looking
forward to getting the T-88 and beginning to glue them all together. I
still need some 1/16" marine ply (any suggestions on a cheaper source
on this?) but I can at least start cutting the poplar into even
smaller sticks now.
It took us 7 hours, and a lot of sweat, but we had a lot of fun doing
it. Ray and I cut parts for 2 cradles in this same area 19 years ago
when my wife and I found out we were going to have twins. He had the
plans, and we cut the parts in the same drive way we cut the poplar in
yesterday. Funny how things repeat and how important good friends
really are.
I posted all of the pictures we took during the process, including the
peg jig I made for the Riblett 613.5 jig I made. I finally decided on
this airfoil based on a lot of thought. I drew out the rib plot in my
CAD program, then offset the lines by 1/8" and used that line to place
a series of 1/4" holes .75" deep. I made a bunch of 1.25" long pegs
out of 1/4" diameter maple dowels and hammered/glued them into place.
I used my 3 axis mill to do the drilling so I have a 'perfect' plot of
the airfoil, and all the alignments of the pieces are perfect! It's
nice to slide the 1/4" pieces into place and have them fit like a
glove!
So, all I need now is to order the T-88 and some plywood for the
gussets and I can start the assembly process. Oh, yeah, before that I
need to cut those little sticks into many smaller sticks! Well, let
the cutting begin!
Here's a link to the picture folio of the day yesterday, with shots of
the jig as well.
http://picasaweb.google.com/RobertsChristmas2007/PietenpolProject?authkey=Gv1sRgCJiF__Tq2bugtgE&feat=directlink
Mark
Message 43
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| Subject: | And the real work begins... |
Mark,
That's the best thing I've read on this list all day!! Congratulations on
the start up, and welcome to the World of Pietenpol builders!
Gary Boothe
Cool, Ca.
Pietenpol
WW Corvair Conversion, mounted
Tail done, Fuselage on gear
(15 ribs down.)
Do not archive
-----Original Message-----
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Mark Roberts
Sent: Sunday, October 25, 2009 6:43 PM
Subject: Pietenpol-List: And the real work begins...
Well, after futzing around for a few weeks with my 613.5 rib jib jig,
I have finally invested in some rough cut poplar, and turned it into
little sticks yesterday. I went over to my friend Ray's house, and we
spent the day cutting about 15 or so board feet of wood into 109 6
foot long sticks 1/4" x 1/2". We had a lot of fun, and I am looking
forward to getting the T-88 and beginning to glue them all together. I
still need some 1/16" marine ply (any suggestions on a cheaper source
on this?) but I can at least start cutting the poplar into even
smaller sticks now.
It took us 7 hours, and a lot of sweat, but we had a lot of fun doing
it. Ray and I cut parts for 2 cradles in this same area 19 years ago
when my wife and I found out we were going to have twins. He had the
plans, and we cut the parts in the same drive way we cut the poplar in
yesterday. Funny how things repeat and how important good friends
really are.
I posted all of the pictures we took during the process, including the
peg jig I made for the Riblett 613.5 jig I made. I finally decided on
this airfoil based on a lot of thought. I drew out the rib plot in my
CAD program, then offset the lines by 1/8" and used that line to place
a series of 1/4" holes .75" deep. I made a bunch of 1.25" long pegs
out of 1/4" diameter maple dowels and hammered/glued them into place.
I used my 3 axis mill to do the drilling so I have a 'perfect' plot of
the airfoil, and all the alignments of the pieces are perfect! It's
nice to slide the 1/4" pieces into place and have them fit like a
glove!
So, all I need now is to order the T-88 and some plywood for the
gussets and I can start the assembly process. Oh, yeah, before that I
need to cut those little sticks into many smaller sticks! Well, let
the cutting begin!
Here's a link to the picture folio of the day yesterday, with shots of
the jig as well.
http://picasaweb.google.com/RobertsChristmas2007/PietenpolProject?authkey=Gv
1sRgCJiF__Tq2bugtgE&feat=directlink
Mark
Message 44
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| Subject: | Re: And the real work begins... |
Mark,
No need to order the T-88 if there is a Woodcraft store near you. They
stock it. You might find it in a boat store too.
Dave
Mark Roberts wrote:
>
> Well, after futzing around for a few weeks with my 613.5 rib jib jig,
> I have finally invested in some rough cut poplar, and turned it into
> little sticks yesterday. I went over to my friend Ray's house, and we
> spent the day cutting about 15 or so board feet of wood into 109 6
> foot long sticks 1/4" x 1/2". We had a lot of fun, and I am looking
> forward to getting the T-88 and beginning to glue them all together. I
> still need some 1/16" marine ply (any suggestions on a cheaper source
> on this?) but I can at least start cutting the poplar into even
> smaller sticks now.
>
> It took us 7 hours, and a lot of sweat, but we had a lot of fun doing
> it. Ray and I cut parts for 2 cradles in this same area 19 years ago
> when my wife and I found out we were going to have twins. He had the
> plans, and we cut the parts in the same drive way we cut the poplar in
> yesterday. Funny how things repeat and how important good friends
> really are.
>
> I posted all of the pictures we took during the process, including the
> peg jig I made for the Riblett 613.5 jig I made. I finally decided on
> this airfoil based on a lot of thought. I drew out the rib plot in my
> CAD program, then offset the lines by 1/8" and used that line to place
> a series of 1/4" holes .75" deep. I made a bunch of 1.25" long pegs
> out of 1/4" diameter maple dowels and hammered/glued them into place.
> I used my 3 axis mill to do the drilling so I have a 'perfect' plot of
> the airfoil, and all the alignments of the pieces are perfect! It's
> nice to slide the 1/4" pieces into place and have them fit like a
> glove!
>
> So, all I need now is to order the T-88 and some plywood for the
> gussets and I can start the assembly process. Oh, yeah, before that I
> need to cut those little sticks into many smaller sticks! Well, let
> the cutting begin!
>
> Here's a link to the picture folio of the day yesterday, with shots of
> the jig as well.
>
> http://picasaweb.google.com/RobertsChristmas2007/PietenpolProject?authkey=Gv1sRgCJiF__Tq2bugtgE&feat=directlink
>
>
> Mark
>
>
>
> ------------------------------------------------------------------------
>
>
> Checked by AVG - www.avg.com
>
>
Message 45
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| Subject: | Re: And the real work begins... |
Sounds Great!
Don't know on the 1/16 birch, search the internet for a source of
GL-1 or GL-2,
Russell
On Sun, Oct 25, 2009 at 9:54 PM, Gary Boothe <gboothe5@comcast.net> wrote:
>
> Mark,
>
> That's the best thing I've read on this list all day!! Congratulations on
> the start up, and welcome to the World of Pietenpol builders!
>
> Gary Boothe
> Cool, Ca.
> Pietenpol
> WW Corvair Conversion, mounted
> Tail done, Fuselage on gear
> (15 ribs down.)
> Do not archive
> -----Original Message-----
> From: owner-pietenpol-list-server@matronics.com
> [mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of Mark
> Roberts
> Sent: Sunday, October 25, 2009 6:43 PM
> To: pietenpol-list
> Subject: Pietenpol-List: And the real work begins...
>
>
> Well, after futzing around for a few weeks with my 613.5 rib jib jig,
> I have finally invested in some rough cut poplar, and turned it into
> little sticks yesterday. I went over to my friend Ray's house, and we
> spent the day cutting about 15 or so board feet of wood into 109 6
> foot long sticks 1/4" x 1/2". We had a lot of fun, and I am looking
> forward to getting the T-88 and beginning to glue them all together. I
> still need some 1/16" marine ply (any suggestions on a cheaper source
> on this?) but I can at least start cutting the poplar into even
> smaller sticks now.
>
> It took us 7 hours, and a lot of sweat, but we had a lot of fun doing
> it. Ray and I cut parts for 2 cradles in this same area 19 years ago
> when my wife and I found out we were going to have twins. He had the
> plans, and we cut the parts in the same drive way we cut the poplar in
> yesterday. Funny how things repeat and how important good friends
> really are.
>
> I posted all of the pictures we took during the process, including the
> peg jig I made for the Riblett 613.5 jig I made. I finally decided on
> this airfoil based on a lot of thought. I drew out the rib plot in my
> CAD program, then offset the lines by 1/8" and used that line to place
> a series of 1/4" holes .75" deep. I made a bunch of 1.25" long pegs
> out of 1/4" diameter maple dowels and hammered/glued them into place.
> I used my 3 axis mill to do the drilling so I have a 'perfect' plot of
> the airfoil, and all the alignments of the pieces are perfect! It's
> nice to slide the 1/4" pieces into place and have them fit like a
> glove!
>
> So, all I need now is to order the T-88 and some plywood for the
> gussets and I can start the assembly process. Oh, yeah, before that I
> need to cut those little sticks into many smaller sticks! Well, let
> the cutting begin!
>
> Here's a link to the picture folio of the day yesterday, with shots of
> the jig as well.
>
>
> http://picasaweb.google.com/RobertsChristmas2007/PietenpolProject?authkey=Gv
> 1sRgCJiF__Tq2bugtgE&feat=directlink
>
>
> Mark
>
>
Message 46
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| Subject: | Re: Push/pull tubes and rod ends |
This guy must be expecting a party there are two big red barbecue grills up
by the double wide.
On Sun, Oct 25, 2009 at 8:24 PM, Bill Church <billspiet@sympatico.ca> wrote:
> billspiet@sympatico.ca>
>
> This will be my last comment on this thread.
>
> First off, Michael, if you follow through with a push/pull system, you will
> not be the first. It has been done before. Refer to the following link for a
> photo of a GN-1 with such a system:
>
> http://www.westcoastpiet.com/images/Pete%20Smith/Brodhead__20070720_028.JPG
>
> Note that the control tube for the rudder is not tiny. The control tube for
> the elevators is likely buried inside the fuselage, and the elevators are
> most likely built of steel tube, in order to be able to transfer the torque
> adequately. My thoughts are that if this system was an improvement, we would
> see more flying examples of it. Just because it has been done does not mean
> it's a good idea.
>
> Secondly, all of the "opinions" that have been expressed regarding the
> negative aspects of attempting to use a push/pull system on this aircraft
> have been based on sound engineering principles. The reason why nobody has
> offered data to prove your theory wrong is that your "system" has no data
> behind it. There are no dimensions to work with. Not even a basic sketch.
> There are often a thousand ways to achieve the same basic goal, with some
> being better than others, but no one being the "right" way. For instance, as
> one reply stated, the proper size for the tubes is dependent on the length,
> in reference to buckling strength.
>
> Thirdly, unless someone out there decides that they want to do all the
> calculations for you, you will eventually have to deal with all of that
> "language and formulas" that, as you put it, are "over your head". As I said
> before, it's not simple. Once the routing of the system is determined
> (including all pivot points), you will need to determine the loads that will
> be imposed on the system (plus an appropriate factor of safety). From there
> you will be able to determine the loads that will be carried by each
> component, and based on those numbers, you will determine the sizes of each
> component. (There's a reason why it takes four years of university to obtain
> a degree in Engineering).
>
> And finally, all of the above is my OPINION. But my opinion is based on
> more than twenty years experience working as a Professional Engineer. Take
> it or leave it.
>
> Bill C.
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=269403#269403
>
>
Message 47
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| Subject: | Re: Push/pull tubes and rod ends -- Chaffinch |
Tim: The strut design that Hosie chose for the Chaffinich was a round tube with
stream-lining with balsa wood covered with cloth. In all the maneuvers that this
airplane went through I never had one incident of vibrations that were in
any way a concern, Something that paralleled Allen's struts, his struts had no
jury strut help.
Pieti Lowell
timothywillis(at)earthlin wrote:
> Now I don't want to start anything about a guy who has built eight Piets, but
I found very strange his position of the "Chaffinch's" jury struts, very near
the end of the lift struts. My thought has been that you want to place the jury
strut near, but not at the middle of the lift strut. The "not at the middle"
has to do with avoiding the harmonic cited in other posts on our message board.
Near the middle is to optimize the reduction of buckling, as also previously
discussed.
> His other changes seem a matter of taste, esp. since he claims no "Pietenpol"
in the plane's name.
> Tim in central TX
>
> --
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=269424#269424
Message 48
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|
It's funny how the last mile of the marathon seems longer than the rest. I'm in
the final mile with the piet, and my list of "little tidbits" seems miles long,
and the little jobs that appear simple often end up being surprisingly hard.
I just finished the cockpit coamings. Two weeks ago I went out to the workshop
one morning thinking "I"ll do the coamings today, that'll be a fun and rewarding
afternoon job". Two weeks later I'm finishing up. Not all that time was
working on it, but what I thought was an afternoon job, ended up taking me probably
three days.
I also have to be really disciplined with myself not to rush through these things,
as so many are cosmetic, and though not structurally important, are the items
that I will see everytime I look at my Piet. But let me also say for those
who are in earlier in their projects, IT'S ALL WORTH IT!!!!KEEP GOING!!! TRY
TO TOUCH IT EVERY DAY, EVEN IF IT'S FOR TEN MINUTES!!!
I also want to write about something I've been thinking about for the last couple
of years.
Let me encourage all of you who can, to fly your Piet to Brodhead each year, and
once there, to fly it often. Dreamy-eyed enthusiasts come from all over this
country and the world to see Piets flying. There are many builders, or wanna
be builders who have never even seen a real Piet, let alone seen one fly. As
I"m sure most of you know, the sight of the Pietenpols flying at Brodhead is
a powerful shot in the arm of encouragement to dozens to keep building for another
year. I seriously doubt that I would be finishing my plane if it weren't
for my annual pilgrimage to Brodhead.
I have been struck at the last two Brodheads, that while there ended up being a
good turnout, there was noticably less flying than in years past. I attributed
it to the lack of fuel these last two yeras, and some very worn-out pilots
this year. However, please remember what it was like when you were building and
dreaming of the day when your project would take wing. Don't forget how hard
you ran after each taxing plane just to watch it lift off, or how you shot
dozen of photographs of it landing, and how much that first ride meant. If every
pilot did two or three short flights each day, this would add up to a LOT
of flying and encouragement.
I pray that when mine is done, it is reliable enough for me to get up there and
serve my brother and sister builders as others have served me through the years
by treating them to the unforgettable sights and sounds of this magnificent
flying machine from a bygone era patrolling the beautiful skies of Brodhead.
Message 49
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| Subject: | Re: some thoughts |
Nice,
Thanks
On Sun, Oct 25, 2009 at 10:19 PM, Douwe Blumberg <
douweblumberg@earthlink.net> wrote:
> douweblumberg@earthlink.net>
>
> It's funny how the last mile of the marathon seems longer than the rest.
> I'm in the final mile with the piet, and my list of "little tidbits" seems
> miles long, and the little jobs that appear simple often end up being
> surprisingly hard.
>
> I just finished the cockpit coamings. Two weeks ago I went out to the
> workshop one morning thinking "I"ll do the coamings today, that'll be a fun
> and rewarding afternoon job". Two weeks later I'm finishing up. Not all
> that time was working on it, but what I thought was an afternoon job, ended
> up taking me probably three days.
>
> I also have to be really disciplined with myself not to rush through these
> things, as so many are cosmetic, and though not structurally important, are
> the items that I will see everytime I look at my Piet. But let me also say
> for those who are in earlier in their projects, IT'S ALL WORTH IT!!!!KEEP
> GOING!!! TRY TO TOUCH IT EVERY DAY, EVEN IF IT'S FOR TEN MINUTES!!!
>
> I also want to write about something I've been thinking about for the last
> couple of years.
>
> Let me encourage all of you who can, to fly your Piet to Brodhead each
> year, and once there, to fly it often. Dreamy-eyed enthusiasts come from
> all over this country and the world to see Piets flying. There are many
> builders, or wanna be builders who have never even seen a real Piet, let
> alone seen one fly. As I"m sure most of you know, the sight of the
> Pietenpols flying at Brodhead is a powerful shot in the arm of encouragement
> to dozens to keep building for another year. I seriously doubt that I would
> be finishing my plane if it weren't for my annual pilgrimage to Brodhead.
>
> I have been struck at the last two Brodheads, that while there ended up
> being a good turnout, there was noticably less flying than in years past. I
> attributed it to the lack of fuel these last two yeras, and some very
> worn-out pilots this year. However, please remember what it was like when
> you were building and dreaming of the day when your project would take wing.
> Don't forget how hard you ran after each taxing plane just to watch it lift
> off, or how you shot dozen of photographs of it landing, and how much that
> first ride meant. If every pilot did two or three short flights each day,
> this would add up to a LOT of flying and encouragement.
>
> I pray that when mine is done, it is reliable enough for me to get up there
> and serve my brother and sister builders as others have served me through
> the years by treating them to the unforgettable sights and sounds of this
> magnificent flying machine from a bygone era patrolling the beautiful skies
> of Brodhead.
>
>
Message 50
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| Subject: | Re: And the real work begins... |
Glad to hear someone is building.....and a new thread has started.
Building ribs is a good test of your stamina to complete the project. I
believe you can get all your rib gussets from a 2ft x 4ft piece of
aircraft plywood, that can be shipped cheaply from Aircraft Spruce.
That is what I did. Just be sure to sand the plywood before you cut it
up so the T-88 will adhere well. I used the little 3/8 inch aircraft
nails to hold the gussets in place.
On another note, just finished up my paperwork package for my
Airworthiness Certificate. Hang in there, it only took me 5 years
Ben Charvet
Mims, Fl
Message 51
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| Subject: | Re: And the real work begins... |
Now you're doing it! Get some T-88 and get crackin. I found the ribs to be a
lot of fun. Once I figured out how to build them, it was kind of like a little
assembly line. Not a whole lot of study required on those once you get going...
just keep putting the little sticks with the big sticks and soon you'll look
up and have a whole pile of em.
Not real sure on the 2' x 4' plywood for all the gussets. I burnt through a 4'
x 4', and then some. I cut my gussets a little large, but close to what the
plans showed... plus I have a vertical in front and behind each spar, so that
consumed a little more material.
Good luck, and keep us posted.
--------
Mark - working on wings
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=269434#269434
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