Today's Message Index:
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0. 09:27 AM - Make Sure You're Listed -- List of Contributors Published Dec 1! (Matt Dralle)
1. 07:26 AM - Re: Short-stack Powerflow exhaust - aerodynamic cover for it? (pkuhns)
2. 07:56 AM - JPI vs EI (Airport Bum)
3. 07:17 PM - Re: Flying with a level (Gary Vogt)
4. 07:18 PM - Re: Re: Short-stack Powerflow exhaust - aerodynamic cover for it? (Gary Vogt)
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| Subject: | Make Sure You're Listed -- List of Contributors Published |
Dec 1!
Dear Listers,
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| Subject: | Re: Short-stack Powerflow exhaust - aerodynamic cover |
for it?
Hi Gary: I'm not sure if you'll see this post but I'll give it a shot:
On October 7th I sent $100 payment for the Powerflow Short Stack fairing. I just
want to see/ask if there's been any progress manufacturing it. You mentioned
having someone else actually build the piece.
Any update would be greatly appreciated.
-- Pete Kuhns
133 West Market Street, Indianapolis, IN 46204
N27161, '79 Cheetah
Powerflow Short Stack Exhaust
GEZ, Shelbyville Indiana
--------
N27161, 1979 Grumman (Gulfstream) Cheetah
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=358625#358625
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Gary.
I know you are known to have noted temp differences between the brands. Can you
clear something up for me.
If your cht is a theoretical 350 which would give the number closest to 350?
You say that jpi reads higher. Does that mean that the ei would show a number
lower than 350, or that the jpi would read higher than 350?
Thanks for clearing this up for me.
Kevin
Message 3
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| Subject: | Re: Flying with a level |
One of the Tigers I maintain has one wing that is off by about a degree.
-It's tough to determine a degree using a laser at 30 feet, but I think o
ne wing is off a bit. -I read the manual about changing the incidence ang
le and it seems to me that without jigs, it would be a real MoFo. -=0A=0A
I thought about the microswitch thing many years ago when I first read it.
-If anything, it determines the drag vs thrust at various speeds.=0A=0ABo
b, it's too bad you aren't closer. -If you have enough spare parts, I'd b
e willing to investigate optimizing the wing/horizontal angles. -I'd love
to build a 1200 lb Tiger with 75 gallons of fuel.=0A=0AWe know that the mi
nimum drag configuration of the wing is at zero degrees. -So, if the fuse
lage tucks a couple of degrees as speed increases, that tells me that as th
e lift of the wing increases, it needs less lift and is naturally finding m
inimum total minimum drag; i.e., max L/D. -=0A=0AThe drag on the fuselage
could be modeled in a water tunnel. -I would pick something near 1/5 sca
le minimum. -Something in the 40 to 50 inch range. -That would be somet
hing very interesting to model. -=0A=0ATrim drag amounts to less than 5%
total drag on the plane. -I'd be looking for big effects first. -I thin
k better wing tips would save that much.=0A=0AGary=0A=0A=0A=0A=0A__________
______________________=0A From: "n76lima@mindspring.com" <n76lima@mindsprin
g.com>=0ATo: Gary Vogt <teamgrumman@yahoo.com> =0ACc: 923te@att.net; bob.ho
do@yahoo.com =0ASent: Sunday, November 20, 2011 9:54 PM=0ASubject: Re: Flyi
ng with a level=0A =0A>When I was a young engineer, I used to go to my supe
rvisor with all of these ideas I had for projects >that we'd likely never w
ork on or problems that may or may not occur and I'd say, "Jay, what if . .
. ."- >Then, he'd tell me to go solve a real problem.- I always had lo
ts of ideas that I thought would be >interesting to try.- He called it me
ntal masturbation.- He'd say, "At least you feel like you're >accomplishi
ng something whether or not you actually do."=0A>OK, so, now I know the obj
ective.- Any ideas on where to start?=0A=0AI'd rather consider it an exer
cise in being open-minded about the possibilities, but I have collected up
nearly all the parts needed to build an amateur-built "replica Tiger", from
a handful of salvage planes, like you suggested you'd like -- AKA the Tige
r "kit", so they aren't necessarily ideas that are never going to be put in
to practice.=0A=0AIn speaking with Roy LoPresti back in the 90's he remarke
d that he felt there was another 10-15 mph left on the table by Grumman whe
n he did his Traveler conversion to the Tiger.- But Grumman declined to f
und additional research after he beat all the 200 HP retracts by at least 1
mph, so they had the advertising edge they wanted.=0A=0AI'd like to explor
e where those theoretical knots are hiding and see what could be done to ex
ploit some of them.- Kevin Lancaster and I had a discussion recently when
he visited my shop.- I know his #1 priority has to be getting the Tiger
LLC version of the AG-5B back on-line, but we talked about some potential m
ods for the future, IF there is a future for new planes in GA.=0A=0AI learn
ed from this recent exchange with you, Ned and Bob H. that you think the wi
ng is set at ~3-3.5 degrees incidence relative to the fuselage waterlines,
and from Ned and Bob H. that the fuselage DOES tuck nose down as the speed
increases, something approaching 2 degrees as the speed exceeds 150 knots.
=0A=0AThis is good information, and pushes my thought experiment further do
wn the line, to asking "what if" the wing incidence could be altered.- Ea
ch degree of incidence at the spar is less than 1/16" of hole movement, so
doing the approved "repair" of the center section and wing spar tube of rea
ming over-size and putting bushings in, could be used to move the center se
ction hole one way and the wing spar tube hole the other, and with 7/16" ho
les, the incidence could be lowered just over 2 degrees.- Given Ned and B
ob H.'s numbers, this would set the fuselage to be more aligned with the fl
ow at 150 knots and above.=0A=0AHow much drag would this save?- Don't kno
w.- I pinged Maynard about incidence and got a response I have not shared
.- But it is my understanding that the change in tail incidence he used t
o espouse was done by several (Mean Gene included) and that they saw very m
easurable gains.- Yes the Tiger tail is bigger, and possibly the gains ar
e not the same.- I was wanting to get a consensus of what knowledgeable G
rumman modifiers thought about such things, and hoped that someone might pi
pe up and say "we did that one time and it didn't do any good", or other co
mments that would either encourage the prospect of testing for an improveme
nt, or anecdotal evidence that ideas being discussed were aerodynamic dead
ends.=0A=0AAnd changing the FUSELAGE incidence with respect to the wing wou
ld change things even more than Maynard's tail incidence adjustment that le
ft the fuselage tilting nose down at high cruise.- He was focused on the
tail trim issues at high speeds where less and less down force was needed a
nd the aerodynamic forces rise significantly at "high Q".=0A=0AI rather ima
gine that there is little chance that many of these ideas will be tried, be
cause as you point out, they are certified planes, and we are talking about
things that would seem to be firmly in the Experimental R&D area, for whic
h we probably don't have the budget.- But if those parts sitting on the s
helf to find themselves mixed with some new aluminum sheet, I'd want to hav
e all the good ideas in one place, since the process of building ANY homebu
ilt is a multi-year commitment, and one doesn't want to have to go back and
re-make things.=0A=0AThanks for your time.=0A=0A--Bob Steward
Message 4
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| Subject: | Re: Short-stack Powerflow exhaust - aerodynamic |
cover for it?
Hi Pete,-=0A=0ADave had the first one stick in the tool. -It really mes
sed up the tool. -He's got it repaired and is planning on making me a cou
ple.=0A=0AI appreciate you writing. -I haven't forgotten.=0A=0AGary=0A=0A
=0A________________________________=0A From: pkuhns <pkuhns@gmail.com>=0ATo
: teamgrumman-list@matronics.com =0ASent: Monday, November 21, 2011 7:23 AM
=0ASubject: TeamGrumman-List: Re: Short-stack Powerflow exhaust - aerodynam
uhns@gmail.com>=0A=0AHi Gary: I'm not sure if you'll see this post but I'll
give it a shot: =0A=0AOn October 7th I sent $100 payment for the Powerflow
Short Stack fairing. I just want to see/ask if there's been any progress m
anufacturing it.- You mentioned having someone else actually build the pi
ece. =0A=0AAny update would be greatly appreciated. =0A=0A-- Pete Kuhns=0A1
33 West Market Street, Indianapolis, IN 46204=0A=0AN27161, '79 Cheetah=0APo
werflow Short Stack Exhaust=0AGEZ, Shelbyville Indiana=0A=0A--------=0AN271
61, 1979 Grumman (Gulfstream) Cheetah=0A=0A=0A=0A=0ARead this topic online
here:=0A=0Ahttp://forums.matronics.com/viewtopic.php?p=358625#358625=0A
-========================
- - - - - - - - - - - - - - -Matt Dralle, List
======
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