Today's Message Index:
----------------------
1. 04:11 PM - rudder weight DF (Nick Harris)
2. 04:59 PM - Re: rudder weight DF (PIETLARS29@wmconnect.com)
3. 05:18 PM - Re: B-17 flight (video) (Tom Stinemetze)
4. 06:54 PM - Re: rudder weight DF (Graham Hansen)
5. 08:39 PM - Re: rudder weight DF (Dick Navratil)
Message 1
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Subject: | rudder weight DF |
All,
A few weeks ago I posted a message wondering if there is a difference in weights
of the same size stick of DF. The consesnsus was if the moisture content was
the same then each stick should be about the same. Today I weighed my rudder
which is about 97% complete (no covering or metal fittings) and it came out
to be 3lbs. Is does anyone think this is to heavy or just about right for DF.
I would not even have questioned it but my DAD said he thought it was heavy.
He was comparing it to a cub rudder though. I dont think you can compare tubing
to wood. I am really getting into the project and think I could finish the
whole tail section by the end of Nov. If the weight is way out of line I need
to make some changes now before I go onto the next part. What ever the case
I don't think I will scrap my parts I have finished (rudder, VS). I will just
make up for it somewhere else.
Nick Harris
Message 2
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Subject: | Re: rudder weight DF |
Nick,
About the weight if your rudder; doesn't seem bad at all.
Regarding wood in general and DF in particular, its all about density which
depends on several things.
The densities of wood from the same tree can vary considerably depending on
the rate of growth. Its the proportion of the sections of the growth 'rings'
like the darker, harder streaks vs the lighter, softer portions.
My piet is almost completely DF and I found a big difference between the
'sticks' I selected. In fact I made it a point to 'heft' each of the pieces
that I found acceptable and bought the lightest ones. In building my laminated
spars, I used 14' 2x4s which I ripped into 8 strips. I could weigh each strip
and I color coded the ends base on weight. Made about 6 different classes.
Nominally spruce density is about 25 or 26 lbs/cu. ft. My strips weighed out
between 26 and 30 lbs/cu ft.
A good source of information on wood is the book: 'Understanding Wood' by R.
Bruce Hoadley
This proved to me that you have to be as selective as is reasonable in
getting your materials. Also noted that the heavier the stick the more brittle
it
is.
Anyway thats what I learned.
Good luck with your building.
Lou Larsen
PS Assembled the piet for the Chapter 'show and tell'ast week and also so I
can get it weighed and do the W & B.
Message 3
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Subject: | Re: B-17 flight (video) |
Surly you jest! That was "way cool" as some generation a while back
used to say.
Sorry for the quality of the video, keep in mind this was my first
time using
the camera (I bought it the day before). It was also my first try
at editing
video, and I was trying to do other "crew duties" while taking the
video, so a
lot of it didn't turn out great.
Building and dreaming in McPherson.
Tom
____ | ____
\8/
/ \
Message 4
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Subject: | Re: rudder weight DF |
Nick,
It sounds as if your rudder weight is "in the ball park" for an uncovered unit,
less metal fittings.
During the early 1970's, I helped a friend build a Pietenpol. The wood he used
was Sitka Spruce and all plywood was Finnish Birch, aircraft quality. I don't
have the final empty weight handy, but still have the weights of various components
which we recorded. Hopefully, they will be of use to you and others for
reference:
COMPONENT UNCOVERED COVERED
***************** **************** *************
WING PANEL 50.5 lb 63.5 lb
CENTER SECTION N/A 22.5 lb
RUDDER 3.5 lb 4.5 lb
VERTICAL FIN 1.5 lb 2.25 lb
TAILPLANE 6.0 lb 8.75 lb
ELEVATOR 3.0 lb 4.5 lb
AILERON 4.0 lb 5.5 lb
NOTE: These figures are to the nearest quarter pound.
The spruce spars were 1" x 4 3/4" along their entire length. Possibly, several
pounds per wing panel could have been saved by routing the spars as shown in the
plans.
The front lift struts were made from Aeronca front strut material which is heavier
than necessary (cost was a factor in choosing them). The rear lift struts
were made from Aeronca rear strut material, as were the center section (cabane)
struts. The combined weight of lift struts and jury struts, strut bracing wires
(1/8" a/c cable), tail bracing wires (3/32" a/c cable), hardware and fittings
was about 30 pounds.
The covering material was 3.5 OZ. per sq. yard polyester fabric, which probably
is heavier than required for the light wing loading and slow speed of a Pietenpol.
Nevertheless, the airplane is still flying with its original fabric cover
30 years later. Butyrate dope was used. The total weight of the doped fabric
cover for the above components is 36.5 pounds. The weight of the fuselage cover
was not recorded, but is likely less than 10 lb, so the total weight of the
doped fabric cover for the entire airplane should be about 45 pounds.
By using a lighter grade of fabric and a minimum amount of finishing material (eg.
dope, etc), some weight may be saved. But when the entire cover weighs only
45 pounds, it won't be too significant in the big picture.
With the exception of the larger wood pieces (spars and longerons, for example),
substituting Douglas Fir for Sitka Spruce won't add much weight to a component.
You can rather easily compensate for this added weight by using a minimum
of instruments, lightweight seat cushions, a lightweight fire extinguisher, lightweight
(eg. Slick) magnetos, a wooden propeller, and avoiding oversize tires.
A single piece wing could save as much as 15 pounds (Ref. B.H. Pietenpol himself).
When I recovered my Pietenpol some 20 years ago, I weighed the various components
and their weights were comparable to the weights provided herein--with the
exception of the wing panels. My wings have Douglas Fir spars built up to the
I-Beam section in the plans by laminating, and this apparently added a few pounds
to each panel. Yet the empty weight of my airplane is significantly less than
the empty weight of the aircraft described above (which was built from the
same jigs!).
I hope this helps.
Graham Hansen (Pietenpol CF-AUN)
Message 5
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Subject: | Re: rudder weight DF |
Nick
I just weighed mine at 2lb. 11oz. That is fully finished, 2 coats of varnish,
West System epoxy on exposed edges and hinges installed. I used Sitka. Dont
worry about small amounts like this. Some of the difference can be in our scales.
Dick N.
----- Original Message -----
From: Nick Harris
To: pietenpol-list@matronics.com
Sent: Saturday, October 29, 2005 6:10 PM
Subject: Pietenpol-List: rudder weight DF
All,
A few weeks ago I posted a message wondering if there is a difference in weights
of the same size stick of DF. The consesnsus was if the moisture content
was the same then each stick should be about the same. Today I weighed my rudder
which is about 97% complete (no covering or metal fittings) and it came out
to be 3lbs. Is does anyone think this is to heavy or just about right for DF.
I would not even have questioned it but my DAD said he thought it was heavy.
He was comparing it to a cub rudder though. I dont think you can compare
tubing to wood. I am really getting into the project and think I could finish
the whole tail section by the end of Nov. If the weight is way out of line I
need to make some changes now before I go onto the next part. What ever the
case I don't think I will scrap my parts I have finished (rudder, VS). I will
just make up for it somewhere else.
Nick Harris
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