Today's Message Index:
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1. 12:56 AM - Re: Axle Placement (CatDesigns)
2. 06:00 AM - Re: Fuse choices (Bill Church)
3. 06:19 AM - Re: Starting my build, but need to know which fuselage to build! (Bill Church)
4. 06:28 AM - Re: Axle Placement (Bill Church)
5. 07:45 AM - Re: Axle Placement (Catdesigns)
6. 08:54 AM - Re: Axle Placement (Catdesigns)
Message 1
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Tony
My research has been documented here
http://westcoastpiet.com/wood_gear_placement_analysis.htm and the weight
and
balance sheet I refer too is attached.
In summary If you built it to the plans:
The steel landing gear plans for the short fuselage show the axel is 17
inched behind the firewall. That would imply the axel ( steel gear) on
a
long fuselage should be at 19 inches (add two inches because of the
2-inch
addition to the front bay of the long fuselage)
If you placed the axel per the wood gear plans the axel should be
farther
forward at 13 =BC-inches (short) or 15 =BC-inches (long) from the
firewall.
Now because yours is the wood gear, do you follow the wood gear plans or
the
steel gear plans?
Just for reference the wing LE with the center struts vertical is at 7
=BD
-inches (short) or 9 =BD -inches (long).
What made me rethink the whole axel location AFTER I finished my gear
was
when William Wynne and I got into a long discussion about his weight and
balance article and his advice to have the axel even with the leading
edge.
While digging through my Pietenpol literature to prove he was wrong I
found
the attached weight and balance sheet that was part of the Corvair
engine
supplement when I purchased the plans. I don=92t even remember receiving
it
with the plans and never really looked at it because I=92m not using a
Corvair. What it did do was to prove he was more correct than I was.
Here is my comments I sent to William:
When I received my plans, I also received a 6 page document entitled
=93Converting the Corvair Engine=94. On page 1 Mr. Pietenpol lists the
empty
weight of the airplane using this modified Corvair engine at 622 pounds,
which is the same as the one on the weight and balance sheet mentioned
above. On page two Mr. Pietenpol list the modifications to this plane.
The
important ones for this discussion are:
-fuselage lengthened 9 inches (the genesis of the LONG fuselage)
-Wings slanted back 3 inches
-wheels moved forward 7 inches.
Using a little math, if the split axel landing gear legs were built per
the
plans the axel would be 19 inches from the long fuselage firewall (17
inches
for the standard plans fuselage plus 2 inches more for the LONG fuselage
extension of the first bay). Then moving the axel forward 7 inches
would
put it at 19-7= 12 inches back from the firewall. The wing was at 7.5
inches on the standard fuselage plus 2 inches (extension of the first
bay)
puts the wing at 9.5 inches behind the firewall plus the 3 inch slant
puts
the wing at 12.5 inches from the firewall. This brings us back to the
0.5
inch measurement but in this case its axel in front of the wing. This
modified airplane Mr. Pietenpol speaks of must be the same as the "1966
Pietenpol Air Camper Powered with a 110-66 Corvair Engine" airplane
shown on
the weight and balance sheet. However, Mr. Pietenpol goes on to say on
page
2 that 7 inches was too much. He recommends splitting the difference
which
would mean the axel should be at 12+3.5=15.5 inches behind the
firewall
(which oddly enough is the distance of the wood gear on a long fuselage)
or
3 inches behind the leading edge of this aircrafts wing. (If you look at
the
picture you can even see that the axel is about even with the leading
edge
and there is no sweep to the front gear leg. )
Some stuff reported on the Pietenpol discussion list:
Chuck Ganzer , NX770CG, has a short fuselage, with the axel at 17 aft of
the
firewall, wing back 3.5 inches from vertical. If you have ever seen him
stand on the brakes and spin, you would not think the wheels are too far
back.
Dick Navratil, =93I re-measured mine today to confirm. My short fuse has
axle
19" back from FW and axle is 3.5" aft of LE. The new plane (Radial
engine
one) has long fuse has axle 21" back and wing isn't mounted yet. My
short
fuse has a CG with min fuel and me at 19.05 and flies perfect. You are
on
the right track. dick N.=94
Don Emch, NX899DE has long fuselage (1966 model), Wing is slanted 4" aft
of
plans, A-65 engine mount is 1" longer than plans (just a little extra
without losing 'the look', Axle is 1" forward of steel gear plans.
Dick N. =93I built the long fuselage with an A65 (mount extended about 1
3/4"
to anticipate my bodily weight of 215") And had to move the wing back 3
inches. I used the split gear plans supplied. Flies fine=94
Lastly, in an article about landing gear design published in Sport
Aviation
by Ladislao Pazmany, he states "The main gear should contact the ground
at
least 15 degrees ahead of the most forward center of gravity and 25
degrees
at the most rearward CG with the aircraft in level attitude." This
center
of gravity is the CG of the plane and on a parasol plane it is somewhere
below the wing. Unfortunately, I don't know where this point is on a
Pietenpol. Some have suggested it is about the center of the instrument
panel but that is just a guess. As an aside I also found in
"Aeronautical
Engineering and Airplane Design" published in 1918, the landing gear
should
be at 13 degrees 10 minutes. It also assumes the CG is the same height
as
the propeller. This 15-25 degrees is in many publications.
Where does this leave you? Basically it really depend on where your wing
is
going to end up. How much you slant to the center supports will effect
where
axel needs to be because it determines the CG. If your guessing, try to
keep
it with 0 to 3 inches behind where you think the leading edge will
ultimately be located.
Chris
Sacramento, CA
WestcoastPiet.com
-----Original Message-----
From: owner-pietenpol-list-server@matronics.com
[mailto:owner-pietenpol-list-server@matronics.com] On Behalf Of
tonyp51qa
Sent: Monday, February 22, 2016 6:59 PM
Subject: Pietenpol-List: Axle Placement
WOOD landing gear axle placement. Hello, I'm building the long wood
fuselage
and I need to know the dimensions for the placement of the landing gear
axle. I have read 20 inches, 21 inches and 17 inches. I will be using a
CORVAIR motor.Thanks!
Tony
--------
Tony Crawford
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=453076#453076
List
7-Day
Message 2
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| Subject: | Re: Fuse choices |
Actually, no, the plans do NOT show any dihedral.
Dave's Piet wrote:
> I believe the BHP plans make note of adding a very small amount of dihedral (1"
at each tip?), for aesthetic purposes because the wing looks as though it is
drooping at the ends even when it is perfectly flat.
>
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=453084#453084
Message 3
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| Subject: | Re: Starting my build, but need to know which fuselage |
to build!
Dave,
What you nee to take into account is "where are the differences between the long
and short fuselages located?" If you study the plans, you will see that certain
bays are longer, and others remain unchanged. Some of the additional length
is located ahead of the CG, and some is located behind. Ultimately, the goal
is to ensure that the CG within the acceptable range, relative to the wing
leading edge. By shifting the wing back, what you are actually doing is shifting
the fuselage forward, relative to the wing. Since all the weight of the
fuselage (including the engine and pilot) shifts forward, the effect is powerful.
Extending the motor mount will have an effect on the CG, but nowhere near
the effect that slanting the cabanes will have.
Bill C.
Dave wrote:
> Bill, that of which you speak are the very things that confuse me just a little-
You would think that if the Continental engine mount was designed for the
173.375" fuselage, and then you decided to use it on the shorter, 163" fuselage,
that the mount would have to shortened, not extended, in order to keep the
aircraft inside the proper CG envelope.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=453085#453085
Message 4
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| Subject: | Re: Axle Placement |
Chris,
Great reply. Very well thought out and researched.
One question, though. When reading your post, it appears that certain characters
don't show up correctly. I took a screen grab to show the areas in question
(underlined in red.) So, what did you type in those spaces that show up as
boxes? Enquiring minds want to know.
Bill C.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=453086#453086
Attachments:
http://forums.matronics.com//files/symbols_176.jpg
Message 5
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| Subject: | Re: Axle Placement |
Bill
It's not that exciting....... here it comes...... it's........ 1/2
--------
Chris
Sacramento, CA
WestCoastPiet.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=453087#453087
Message 6
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| Subject: | Re: Axle Placement |
Bill
I went back and fixed the blank spots and typos in the web version. I guess I should
not be posting long emails at 1 am.
to be more specific, the first two are 1/4 and the second two are 1/2.
--------
Chris
Sacramento, CA
WestCoastPiet.com
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=453090#453090
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