Today's Message Index:
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1. 09:55 AM - Re: Substituting .016 for .020 on the skins? (Stanley A Challgren)
2. 08:29 PM - Substituting 020 for 016 (Joe Spencer)
3. 08:40 PM - Re: Substituting 020 for 016 (Joe Spencer)
4. 11:55 PM - Re: Re: Substituting 020 for 016 (JG)
Message 1
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Subject: | Re: Substituting .016 for .020 on the skins? |
Joe:
I did not use a 1 X 4 which is a great idea but did find near the end of
the building process that rolling up the .016 skin each time it was
taken off the aircraft made the process go a lot easier. After rolling
it up I used bungee cords to keep it rolled up. The result was no more
smilies and a lot fewer bad words.
I like your reported 579# and 97 mph cruise with VG's. My estimate for
N701VG on weight and cruise is about the same with the VG's.
Stan
701/3300
On Mar 2, 2010, at 11:55 , Joe Spencer wrote:
> My 701/912s/VG weighs 579# empty with strut cuffs and other cleanup
fairings...it's a heckuva good performer; the takeoff and climbout when
solo and light on gas is shocking. I can't imagine compromising any of
that performance to the least degree especially for subbing 020 for 016.
There isn't any reliability issue associated with the 016 skin that I'm
aware of, the oil canning is a non issue...you get used to it and it
tells you when it's not coordinated, and there was no difficulty
handling the sheets by myself while building. Just clamp a 1x4 along the
edge and pick it up and move it. Mine has a TXP, Encoder, Comm, GPS,
paint and light simple upholstery...the only other things I allowed
myself were the cleanup fairings that more than paid for their weight in
reduced drag(or I would have removed them). It cruises 97 mph at 5000
rpm down low with the Warp Drive set at a thin 11 degrees. I don't think
you'll find any of the heavy ones that will do that...not if the
performance has been accurately measured.
> Once it's built so it'll stay together weight is everything
else...well nearly so. 30# for thicker skin is huge and pointless
>
> Joe
>
>
Message 2
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Subject: | Substituting 020 for 016 |
>Joe:
>I did not use a 1 X 4 which is a great idea but did find near the end
of
>the building process that rolling up the .016 skin each time it was
>taken off the aircraft made the process go a lot easier. After rolling
>it up I used bungee cords to keep it rolled up. The result was no more
>smilies and a lot fewer bad words.
>I like your reported 579# and 97 mph cruise with VG's. My estimate for
>N701VG on weight and cruise is about the same with the VG's.
>Stan
Right, Stan...there must be all sorts of ways to handle the 016 skins
w/o damage besides resorting to 020.
Further thoughts on the thicker skins solution suggested by some
here...the reference to the 020 on the 750 probably is probably hardly
relevant to the 701; that's a larger plane with higher gross weight.
Zenith I feel sure went to the thicker skins because of a load
requirement which doesn't apply to our smaller, lighter plane. Some
mentioned the 020 would make it stronger...we already have a +4G/+6G
(yield) design; why would we possibly need more strength...we're mostly
just a bunch of old farts motoring around and landing in cow pastures
and beaches and such. If we were in a fast mover trying to dodge SAMs
over Hanoi or Bagdad or somewhere well maybe yeah...Zenith has already
designed the thing for our typical mission; why add needless weight? I
work my butt off trying to save a pound or two here and there. To add 30
needless pounds is unthinkable to me. I realize that to some the
building process is more important than the finished product; me, I want
a light good performing machine and realize that minimum weight and
least drag are all important...Bolding and JG got it right
Best
Joe
Message 3
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Subject: | Re: Substituting 020 for 016 |
I did not use a 1 X 4 which is a great idea but did find near the end of
>the building process that rolling up the .016 skin each time it was
>taken off the aircraft made the process go a lot easier. After rolling
>it up I used bungee cords to keep it rolled up. The result was no more
>smilies and a lot fewer bad words.
>I like your reported 579# and 97 mph cruise with VG's. My estimate for
>N701VG on weight and cruise is about the same with the VG's.
>Stan
Right, Stan...there must be all sorts of ways to handle the 016 skins
w/o damage besides resorting to 020.
Further thoughts on the thicker skins solution suggested by some
here...the reference to the 020 on the 750 probably is probably hardly
relevant to the 701; that's a larger plane with higher gross weight.
Zenith I feel sure went to the thicker skins because of a load
requirement which doesn't apply to our smaller, lighter plane. Some
mentioned the 020 would make it stronger...we already have a +4G/+6G
(yield) design; why would we possibly need more strength...we're mostly
just a bunch of old farts motoring around and landing in cow pastures
and beaches and such. If we were in a fast mover trying to dodge SAMs
over Hanoi or Bagdad or somewhere well maybe yeah...Zenith has already
designed the thing for our typical mission; why add needless weight? I
work my butt off trying to save a pound or two here and there. To add 30
needless pounds is unthinkable to me. I realize that to some the
building process is more important than the finished product; me, I want
a light good perfor!
ming machine and realize that minimum weight and least drag are all
important...Bolding and JG got it right
Best
Joe
Message 4
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Subject: | Re: Substituting 020 for 016 |
*Increasing the skin thickness by 25% does not increase the strength of an
aircraft like the 701 by 25%, it's just dead weight. Many years ago I knew
a 701 built with .020, along with a few other 'strengthening' mods
considered essential by the amateur builder, and a heavy Subaru engine. The
flying performance was a complete disappointment to the builder - it was the
classic 'lead sled' just as Bolding predicts.... *
*
*
*That short 701 wing was originally designed for a much lighter 701, with a
2-stroke engine. Since then it's gained a lot of weight, with no more wing.
Beware of adding any more weight at all to this aircraft.......
*
*
*
*I have experience in rebuilding three very bent 701's that had come to
grief on perilous short strips. In no instance would .020 been an advantage
to the result. The wings and fuselage on the 701 are excellent at crumpling
in just the right places to absorb the impact energy, and so protect the
occupants and the rest of the aircraft from damage. *
*
*
*The oil canning issue is easily fixed. Just add .016 angle in the rear
fuselage, and intermediate foam ribs in the wings. Both stuck in with
Sikkaflex or similar polyurethane adhesive. Using the adhesive instead of
rivets is easier, and leaves a more fair surface. This adhesive needs to
have a thick bead to cure properly, so cut the ribs 2-3mm smaller. When
the wing is ready to close, put a good bead of adhesive on the underside of
the foam ribs and set them in place and let the adhesive cure. Check with a
straight edge to see that the upper edges of the foam ribs are just below
the aluminum ribs. Then put a thick bead of adhesive on the top edges, and
rivet the top skins in place. The adhesive will take up any gap and adapt
to the contour of the skin. When it's cured it will hold the skin in place
even better than rivets. Using 10mm (3/8") close-cell polyurethane foam
(same as used by the fiberglass industry), the weight is probably only 1 lb
for the whole aircraft, and very effective.*
*
*
*Once again - If you want good STOL performance, beware of adding any extra
weight to the 701........*
*
*
*JG
*
On Thu, Mar 4, 2010 at 2:36 PM, Joe Spencer <jpspencer@cableone.net> wrote:
> I did not use a 1 X 4 which is a great idea but did find near the end of
> >the building process that rolling up the .016 skin each time it was
> >taken off the aircraft made the process go a lot easier. After rolling
> >it up I used bungee cords to keep it rolled up. The result was no more
> >smilies and a lot fewer bad words.
>
> >I like your reported 579# and 97 mph cruise with VG's. My estimate for
> >N701VG on weight and cruise is about the same with the VG's.
>
> >Stan
>
> Right, Stan...there must be all sorts of ways to handle the 016 skins w/o
> damage besides resorting to 020.
> Further thoughts on the thicker skins solution suggested by some here...the
> reference to the 020 on the 750 probably is probably hardly relevant to the
> 701; that's a larger plane with higher gross weight. Zenith I feel sure went
> to the thicker skins because of a load requirement which doesn't apply to
> our smaller, lighter plane. Some mentioned the 020 would make it
> stronger...we already have a +4G/+6G (yield) design; why would we possibly
> need more strength...we're mostly just a bunch of old farts motoring around
> and landing in cow pastures and beaches and such. If we were in a fast mover
> trying to dodge SAMs over Hanoi or Bagdad or somewhere well maybe
> yeah...Zenith has already designed the thing for our typical mission; why
> add needless weight? I work my butt off trying to save a pound or two here
> and there. To add 30 needless pounds is unthinkable to me. I realize that to
> some the building process is more important than the finished product; me, I
> want a light good perfor!
> ming machine and realize that minimum weight and least drag are all
> important...Bolding and JG got it right
> Best
> Joe
>
> *
>
> *
>
>
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