Today's Message Index:
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1. 12:33 AM - Re: Flying with a level, post script (Gary L Vogt)
2. 10:06 PM - Fw: Flying with a level (Gary L Vogt)
Message 1
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| Subject: | Re: Flying with a level, post script |
A few emails ago I said I had a customer with a plane having a wing with 1 d
egree incidence more than the other. I meant .1 degrees. 1 degree would be e
asy to find.
What got me looking at the wing incidence was how much aileron trim it takes
to fly straight. Every thing else is square on the plane. I used lasers and
aimed at a wall 30 feet away.
Maybe I'll look at it again next annual.
Gary
Sent from my iPad
On Nov 22, 2011, at 9:44 PM, teamgrumman@aol.com wrote:
>
>
>
> -----Original Message-----
> From: Bob Hodo <bob.hodo@yahoo.com>
> To: n76lima <n76lima@mindspring.com>; Gary Vogt <teamgrumman@aol.com>; Ned
Thomas <923TE@att.net>
> Sent: Tue, Nov 22, 2011 1:34 pm
> Subject: Re: Flying with a level, post script
>
> The math shows a 1 degree change in pitch about the wing spar axis will dr
op the leading edge .31" and raise the trailing edge of the flaps and ailero
ns .61"
>
> Will that be problematic for the flap and aileron actuator rods where they
go through the honeycomb? Will it be noticable where the top wing skin mee
ts the fiberglass wing root???
>
> BH
Message 2
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| Subject: | Fwd: Flying with a level |
Did this go out to the list? I didn't see it.
Gary
Sent from my iPad
Begin forwarded message:
>
> 1. No comment
> 2. I said the horizontal was at zero degrees with respect to the canopy ra
ils. I have no clue where zero lift occurs.
> 3. I said between 3 and 3 1/2 degrees. That was based on calculations made
years ago. I haven't checked it with my new fangled digital level. I need t
o do that.
> 4. Based on similar wings (Clark Y, AG03, USA 35B) zero lift occurs betwee
n -1.5 and -5 degrees AOA
> 5. My guess would be that based on the shape of the front of the cowling, t
here is still lift from the front of the cowling. That is still a guess. If i
t is approaching zero lift, tha would be great.
> 6. No comment
> 7. I did?
> 8. I did? I thought I said, based on what I've learned, inlet sizes, weig
hts, white arc, prop choices, that I thought the design speed was 120 knots
. Not for the Tiger. For the Traveler. The Tiger was an attempt to optimize t
he Traveler fuselage/wing combination.
> 9. See previous email.
> 10. Remove both aileron trim tabs. Tighten the cables to 35 lbs. Fine tune
roll with the flaps. Look at the position of the ailerons. If one is still h
igher, determine if the error is not in the wing tip. I've seen wing tips 1/
2 inch different side-to-side.
> 11. No comment
> 12. I didn't know that. I thought all planes had a tendency to pitch up as
speed increases. This is a very well know aerodynamic behavior. It is not u
nique to our planes.
> 13. I've tried every possible combination of rigging of flaps and ailerons
. My flaps are intentionally rigged at 7 1/2 degrees up. Under most flight c
onditions, optimum speed is obtained between 0 and +2 degrees for the flaps.
Under MOST conditions. There is no one single setting for all fuel loads, p
assenger loading, or baggage loading/distribution for optimum speed.
> * it takes an enormous amount of patience to wait for the speed to change b
y 1 or 2 knots for each loading condition. If you want to record each loadin
g and each flap setting for optimum speed, you'll need a lot of dedication.
>
> BH, wing incidence won't gain you much, if any. Look for interference drag
reduction first.
>
>
>
> Gary
> Sent from my iPad
>
> On Nov 22, 2011, at 9:23 PM, teamgrumman@aol.com wrote:
>
>>
>>
>> -----Original Message-----
>> From: Bob Hodo <bob.hodo@yahoo.com>
>> To: n76lima <n76lima@mindspring.com>; Gary Vogt <teamgrumman@aol.com>; Ne
d Thomas <923TE@att.net>
>> Sent: Tue, Nov 22, 2011 1:18 pm
>> Subject: Re: Flying with a level
>>
>> Fellers, I have a rib on loan from Bob S standing next to the TV in the l
iving room. I spend more time looking at the rib.
>>
>> Ned's question about split elevators and clue the other day regarding fly
ing with a level on the canopy rails has really had me thinking.
>>
>> I can only process this stuff by making mental notes and written lists of
a) what I know, and then b) what I suspect, and then c) what might be done t
o improve things, preferably legal things.
>>
>> Here is a partial and quick list of what I know or strongly suspect:
>>
>> 1) Slab sides, and slab bottoms are draggy. Bend them at an angle and th
ey are even more draggy. ( Watch a 18 wheeler pulling a trailer with tarps d
own the sides at how they billow out up front and push in as you go back. ) T
he sides and bottom of our fuselage does this, and the bottom of our wing al
so does it.
>> 2) Gary says the canopy rails are generally considered to be parallel to t
he zero lift line for the fuselage.
>> 3) Gary says the main wing is 3 to 4 degrees higher pitched than that.
>> 4) Bob S says nobody can draw a line across this rib where the zero lift l
ine exists. Anecdotal guessing is our only source at the moment for where t
hat line ought to be.
>> 5) Ned says his canopy rails are 2 degrees down in pitch at 150kn. The m
ath on that says that the wings are now only 2 degrees up and are able to li
ft all the weight AND fight the fuselage and tail which are both now pushing
down.
>> 6) Hodo says his rails are level around 130kn and 1.27 degrees down at 14
0 kn.
>> 7) Gary says the HS is set at 3 to 4 degrees down pitch compared to the c
anopy rails.
>> 8) Gary says the plane was engineered to be sweet and efficient and balan
ced at 120 knots.
>> 9) Gary says he knows of one Tiger that has one wing about 1 degree lower
in pitch than any other he has seen.
>> 10) Hodo says his left wing makes more lift than his right, and his left a
ileron rides higher than the right to compensate. Hodo suspects his new tig
er spar has it's wing bolt holes on the right wing slightly lower than the h
oles for the left wing.
>> 11) Bob S has said a 1/16th inch relocation of the holes for the wing bol
ts gets a 1 degree change in wing pitch. My calculations show it takes abou
t 10% less relocation than that. The point here being, I am really shocked t
hat the fleet would not have a lot of planes with more variation than that.
>> 12) EVERYONE KNOWS this airplane makes too much lift above about 135 kn, t
hat ALL of that extra lift is in the main wing, and the tail comes higher an
d higher to compensate, and drag in the rear end of the plane climbs exponen
tially as it does.
>> 13) EVERYONE KNOWS that you either retract flaps, or rig your ailerons at
the upper limit (or both) to get extra speed, providing you have already do
ne some drag clean ups and have a healthy engine and good prop. The idea is
that we must dump main wing lift, and folks, this is not the most efficient
way to do that.
>>
>> ........................................
>>
>> I am asking myself if the plane wouldn't be faster, and if it wouldn't cl
imb faster if the pitch of the wing were lower, making it work WITH the fuse
lage and the empenage rather than out of synch. I am thinking it would even
be better on final with full flaps to have the nose pitched slightly higher
during the same descent profile. Anyone disagree?
>>
>> I haven't had a chance to talk to Bob S in several days, but am confused a
t the suggestion that the inner two panels being original yankee foils and t
he outer panel being the current one would be better than the other way arou
nd. If you look at the Cirrus wing, it is the outer panel that is lower in p
itch and longer on the front end, and thinner in profile. And both Bob S an
d Gary have taught me that dumping lift at the tips in a blended airfoil is t
he way to go, Bob S on rigging, and Gary on propeller twist. What am I miss
ing?
>>
>> If I have misunderstood or misquoted anyone, let me know. If it is Gary,
don't go off on me, just be patient and correct me. I don't like to be wro
ng, and work hard to weed it out.
>>
>> I really like the AA5-A and B, and would sell mine and buy a kit if they w
ere priced about the same! But I want to re-shape the wing, and maybe the f
uselage too if I can figure out how to do that with honeycomb.
>>
>> Looking forward to the corrections before I plunge further into possible f
ixes.
>>
>> BH
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