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curious - Actual Performance numbers for the RV-9?

mkmuch

mkmuch

Active Member
I searched the archives but I didn't find much information on actual cruise speeds in various configurations for the RV-9 and 9A?

If you have info for your set up please post.

Include...

Top Speed
Cruise Speed
Engine / Prop
Alt the reading were taken
% power / LOP or ROP?


Thanks...
 
Mike,

Probably the reason you don't find them posted is because the actual numbers are so close to what Van's lists on their web sight, if not slightly better.

Here's the link: http://www.vansaircraft.com/public/rv-9per.htm

I know for my -9 with the O-290-D2 and a climb prop, I true at 165 MPH but can see 1800 FPM at 1750 lbs gross. That prop limited me to 65% on the 2600 RPM continuous power redline of my 135 HP O-290-D2. The one time I let it spin up I saw just about 180 MPH at 2870 RPM and that was at 10K feet DA.
 
Thanks

Bill -

I know the VANS specs well... My curiosity was how well does the real world perform with various combinations to the books at VANS?

Thanks for the specs...
 
160hp carbed
F/P Sterba wood cruise prop
184.5 mph top speed (GPS g/s)
160 mph cruise @ 75%
7gph
 
typically

I see the following numbers.

at 8500 ' density altitude.

2400 rpm. WOT. 157-158 knots TAS
2700 rpm. WOT. 161-162 knots TAS

about 8 gallons per hour leaned to 50 rich of peak.
I can usually lean really agressively at this altitude and power setting.

Another power setting that I use a bunch (usually down low) is.
2200 rpm 20 inches 128 knots TAS. leaned back to around 6-6.5 gph.
(Take that you O-235 guys!):D

O-320. 160 hp. carb. Hartzell prop.
 
O-320E3D 150 hp with fixed pitch prop (77" pitch). Only time I ried top speed was with two aboard, full fuel and 1000' alt. Indicated 154 kts. I usually cruise in the range of 4500 - 7500' at 2200-2250 rpm, leaned by the tach, and will true out at 132-134 kts with a fuel burn of 6 - 6.5 gph.
 
160 HP, CS, Dual EI, Carb

I have 2 favorite cruise specs:

1) low - 2500-6500 20.8MP, full carb heat, 2080rpm, ~5gph LOP, 128-130 KTAS

2) high - above 6500 - WOT, partial carb heat, 2270 rpm, 5.9-6.1 gph LOP, 148-151KTAS

I lean very aggressively below 70% power and it runs great.
 
I get about 164kts

WOT between 8k and 10k, leaned for max power.

I virtually never operate that way. Usually I have the power back to about 65% and run LOP.

Fuel burn is not-as-much-as-ROP-GPH
 
Interesting...

I have read several places that RV-9's are only about 10 knots in cruise slower than the -7, based on the book (VANS Numbers) that would appear to be true, based on the responses so far - that delta appears to be much greater, say 20 knots?

I realize I am making a rather broad statement with many assumptions - so I have to use the words "In general, it appears..."

Does this sound about right?
 
mkmuch said:
I have read several places that RV-9's are only about 10 knots in cruise slower than the -7, based on the book (VANS Numbers) that would appear to be true, based on the responses so far - that delta appears to be much greater, say 20 knots?

I realize I am making a rather broad statement with many assumptions - so I have to use the words "In general, it appears..."

Does this sound about right?
Click to expand...
Mike,

Van's tests their planes at 75% power and 8,000' DA which for a FP prop means WOT and leaned for best power.

Very few people run their engines that way, even though they are designed to do exactly that.

If you ask the same question of the RV-7 fliers, you will probably find the same descrepency.

You can trust the Van's numbers. Test after test has proven them out. The fact that most pilots don't fly that way is a different issue.

So your "rather broad statement" is made with bad data.

As posted many times and based on real test numbers, the -9 is only 3 MPH slower than the -7 when equiped with the same engine prop combo.
 
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The performance figures can be hard to find but they are there. Do an Advanced Search with "performance" in the "RV-9/9A" category and be prepared to trawl through the posts. Be aware that there can wide variations due to measurement technique and instrument errors. Also Van states his performance figures for the 9/9A are with a fixed pitch prop whereas 7/7A figures are with a C/S prop. RVs with a constant speed prop are likely to achieve better fuel consumption figures if they run at lower rpms.
My cruise figures are similar to others I have seen. 9A, 0-320, hartzell C/S prop, one mag and one electronic ignition.

8,500 ft Density Altitude:
148 to 150 kts 2,250 rpm and around 6 g/hr, manual leaning to "Best Economy", probably somewhere around 50 % power.
160/161 kts, WOT, 2,300 rpm and around 7.3 g/hr, manual leaning to "Best Economy", probably somewhere around 63% power.

These figures are for the cruise segment only (no taxi, climb or descent).
The speed figures are calculated as accurately as possible using the 4 leg GPS spreadsheet and the fuel consumption figures were calculated by emptying and then filling a tank with a known quantity, flying for a set time then draining and measuring what was in the tank.

Fin
9A
 
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Mike, my 9A performs better than all of the Van's published numbers by a couple MPH. I can't get 1900 fpm climb except for the first 2000 ft. I have an 0-320 (160 HP) and a fixed pitch . Several other RVer's have told me that my 9A is exceptionally fast. I do like to spin my prop....I rarely spin it under 2450 rpm. Also, I can't get it to burn over 8.2 gal. at any altitude. At 10,000 my TAS is bumping 200 mph at 6.8 gph. If I can only get my autopilot to act right. LOVE MY 9A!!!!!!!!
 
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same engine prop combo?

N941WR said:
Mike,

Van's tests their planes at 75% power and 8,000' DA which for a FP prop means WOT and leaned for best power.

Very few people run their engines that way, even though they are designed to do exactly that.

If you ask the same question of the RV-7 fliers, you will probably find the same descrepency.

You can trust the Van's numbers. Test after test has proven them out. The fact that most pilots don't fly that way is a different issue.

So your "rather broad statement" is made with bad data.

As posted many times and based on real test numbers, the -9 is only 3 MPH slower than the -7 when equiped with the same engine prop combo.
Click to expand...

Just to clarify - What do you mean same engine prop combo? The 9 wont take a 180 or 200 but I guess I follow you if you mean a -7 with a 160hp?

Did i misunderstand?
 
mkmuch said:
Just to clarify - What do you mean same engine prop combo? The 9 wont take a 180 or 200 but I guess I follow you if you mean a -7 with a 160hp?

Did i misunderstand?
Click to expand...

Vans does not like it much at all, but there are quite a few -9's flying with 180hp. Mine will be one of them.
 
mkmuch said:
Just to clarify - What do you mean same engine prop combo? The 9 wont take a 180 or 200 but I guess I follow you if you mean a -7 with a 160hp?

Did i misunderstand?
Click to expand...
What I'm saying is that if you compared an RV-7 and an RV-9, both with identical engines (O-320's. Yes, the -7 is designed for the O-320.), the same prop (either FP or CS), the same ignition, etc. there should be just a few MPH difference between the two at 8,000' DA. That also assumes they are flown the same; same RPM, same leaning technique, etc.

I suspect but don't know, if you took those two airplanes up where you need O2, the -9 might be slightly faster due to its more efficient wing. (That comment should open a can of worms.)
 
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My 6A ( Lyc 180 C/S prop) is about 20 mph faster than the 9A (160HP C/S prop) that I regularly fly with. The 9A can land 10 mph slower though.

L.Adamson
 
N941WR said:
I suspect but don't know, if you took those two airplanes up where you need O2, the -9 might be slightly faster due to its more efficient wing. (That comment should open a can of worms.)
Click to expand...

Don't count on it........:D

Turns out that my 1172 lb. RV6A is a speed demon! Why.............I don't know! :)

L.Adamson --- RV6A (flying)
 
GETST8FRM said:
Mike, my 9A performs better than all of the Van's published numbers by a couple MPH. I can't get 1900 fpm climb except for the first 2000 ft. I have an 0-320 (160 HP) and a fixed pitch . Several other RVer's have told me that my 9A is exceptionally fast. I do like to spin my prop....I rarely spin it under 2450 rpm. Also, I can't get it to burn over 8.2 gal. at any altitude. At 10,000 my TAS is bumping 200 mph at 6.8 gph. If I can only get my autopilot to act right. LOVE MY 9A!!!!!!!!
Click to expand...

scard said:
Wow, I'm impressed. Did you build it? If that were my airplane, I'd be checking my instrumentation and numbers.
Click to expand...

Your figures look good and I can understand why you love your 9A. Not many aircraft have both a slow stall speed and a decent cruise speed. I see you purchased your 9A. If you want to test the accuracy of your TAS speeds and compare your performance to other 9As, can I suggest you fly at 8,500 ft density altitude and use the 4 leg Excel spreadsheet to calculate you TAS. http://www.ntps.edu/HTML/Downloads/ Click on GPS PEC Spreadsheet and select 4 leg at the bottom.
As a point of reference my 9A does about 170 kts (195/196 mph) at 8,500 ft density altitude WOT and 2,700 rpm.

Fin
9A. 0-320, Hartzell C/S prop, EI and mag, 9:1 comp ratio.
 
My 9A has a 160, Catto three blade and E-mag/P-mag combo. The only "speed mod" not almost universal is a nose gear fairing. It came in at 1054 lb empty. Solo with half fuel numbers on a standard day (if there is such a thing!) beat Van's by a bit:

8,000 WOT 192 mph @ 6.9gph. Sorry, didn't record rpm.
1800 fpm measured 3-4000'.
Normal cruise at 4-6000' 150-160 @ 4.5-5.0
Normal ROC 12-1500 fpm @ 105-115 mph
It IS faster up high, but I don't have firm numbers. I wouldn't dispute "bumping 200" on an EI 9A but have never done a three way run to get it accurately.

Bob Kelly
 
I have a 160 HP ECI Titan up front with the recommended Sensenich prop. I live in Utah so the average cruise altitude is 7500 or 8500 depending on direction (sometimes higher, sometimes lower depending on distance and terrain). Average a/c configuration is solo/full fuel/10 lbs of stuff in back.
After WOT and full rich climb, I pull back to cruise at 22" MP and 2400 rpm and leaned to approx 1300 deg F.
The average GPS 2-way ground speed is 150 kt. (IAS hovers around 140 kt / 155 mph). TAS calculates out to be right around Vans 186 mph. Fuel burn has never exceeded 8 gph.
I use 150 kt and 8 gph as flight planning constants and usually arrive within minutes of the estimate and with fuel to spare.
 
thx Steve

Your description is exactly what I was looking for... Done some more recommended search and the performance numbers are narrowing...

Still searching for more info than what I've found on the next question...

What are the performance gains of a 180 or 200hp in the rv-9? feel free to add that to the response for those of you with that installed base.
 
Two recent tests

I recently did a couple of TAS tests with my 9A. I needed to send my Catto prop back to Craig for a refinish and I wanted to have some pitch added. The Catto is a 66 x 70, the three way GPS run was done at 9100 PA. The TAS came out at 185 MPH. I didn't get the temp or dew point :eek: At this altitude I was WOT and cranking at 2720 RPM

I then put my old Sterba prop back on. Next week same conditons 9100 PA. The Sterba is a 68 x 76 and the TAS came out at 179 MPH. RPM was around 2550 WOT. This is the same as the original flight tests with this prop.

I assume the DA was conservatively 10,000. Should have got the temps I know, but I forgot.

My 9A has an H2AD 160 HP with the Dual Mag pack.
 
mkmuch said:
...What are the performance gains of a 180 or 200hp in the rv-9? feel free to add that to the response for those of you with that installed base.
Click to expand...
Oh no! Please say you didn't ask about putting a larger than recommended engine on your RV-9. You had better duck!

Seriously, the -9 was designed for the O-320 160 HP as the max. A number of people have installed 180 HP O-360's and one guy had his engine dynoned at well over 200 HP. Typically airplanes gain a good bit in ROC but little in TAS when larger engines are installed. The down side is the decrease in useful load.

People have done it but it is not recommended. Continue searching Grasshopper and you will find the answers. They are there, hidden among the trees.
 
hahahaha!

Never dream of going out of spec to what VANS says... I do not have that kind of engineering degree... Was just curious because I know several people have - so was curious what they found with that wing (being unique).:D
 
calculate'em

You can get a real close estimate.

The speed increases to the cube root of the power increase so.
180 horse from 160 is a 12.5 percent power increase and gives about a 4 percent speed increase.

So with my 160 knots with 160 horses, I would expect about 166 knots with 180 horse (along with about 1 more gph fuel burn)



mkmuch said:
Your description is exactly what I was looking for... Done some more recommended search and the performance numbers are narrowing...

Still searching for more info than what I've found on the next question...

What are the performance gains of a 180 or 200hp in the rv-9? feel free to add that to the response for those of you with that installed base.
Click to expand...
 
David works in Rocket City...

David Edgemon was my "nearby" RV-9A builder who helped me during the construction of my RV-9A. He was about three months ahead of me all through the construction. He is an engineer, albeit in Electrical Engineering, same as me. The application of logic and math to any issue usually reveals the underlying facts.

Bottom line, most of us like to fly around 160 MPH TAS to save gas in the 5.5 to 6 gallons per hour range.

As for my personal test of my RV-9A, 160 HP ECI O-320, carb, Hartzell C/S prop, 1 MAG, one LSE Plasma III, maximum speed at 1000 MSL is 194 MPH, burning 11 GPH according to the fuel flow on the GRT engine monitor. And yes, that was turning 2,300 RPM and 28 inches MP WOT for a short high-speed pass down the runway at two different airports.
 
the numbers

my apologies for 'rough' numbers, but it IS interesting to see the variations.
How exactly to I get it to go 198 mph?? :) downhill?

My 9a
'normal' cross-country operation at about 7000'
fully faired etc.
Cruise Speed 125 kts indicated at 2250 rpm, close to TAS as borne out by arrival time. about 7 gph.
Engine / Prop carbed 0-320 150 hp sens. 72x77
 
flyboy1963 said:
my apologies for 'rough' numbers, but it IS interesting to see the variations.
How exactly to I get it to go 198 mph?? :) downhill?

My 9a
'normal' cross-country operation at about 7000'
fully faired etc.
Cruise Speed 125 kts indicated at 2250 rpm, close to TAS as borne out by arrival time. about 7 gph.
Engine / Prop carbed 0-320 150 hp sens. 72x77
Click to expand...

Yes, big variations which make it hard to compare the data. IMHO the best way to calculate TAS is to use the GPS spreadsheet (see post #22) and if you have an autopilot, fly 4 legs at 90 degrees apart (fly track, not heading for this spreadsheet) and at some standard altitude, say 8,500ft Density Altitude. You may want to use this spreadsheet to calculate your cruise TAS at your normal cruise altitude. If you are indicating 125 kts then I suspect your TAS would be well above this.

Fin
9A
 
Idea on Variations

Back to the photo requests. :) There are times that I've done a Linda Blair impression in flight and looked at the elevator counter weights on my planes tail. Mine are clearly up in the airstream which means the rear of the elevators are down in the wind and appear to be causing a lot of drag at my typical cruise speed. Early on I called Van's tech support to see if this was set up incorrectly when the horizontal stab was mounted. On Cherokees and Comanches with the flying stabilator an aft loaded plane is significantly faster because the tail isn't creating so much drag. It seems like those 10 foot wide elevators on my 9 would cause the same problem. Regardless of my theory's validity I was told that the elevator is supposed to ride the way mine is because the plane will fly more stable and hold altitude better. I didn't adjust the angle that the horizontal stab was mounted at after getting the advice. Regardless, I bet this affects the speed. Thoughts? Pictures of your tail in cruise?
 
Not sure whether this is the photo you are looking for. My counter balance weight is up. This was taken two years ago at 9,500', 75% power, 2520 rpm and 159 kts, burning 8.3 gph.
IMG_7741.JPG


I just accept as what it is and have no wisdom on this one.
Following is my speed chart at 8,500' during my phase I. I have a fixed pitch propeller and 160 HP carb engine.
airspeed.jpg


Nowadays I lean very aggressively. As long as I am below 75% power (I have GRT engine monitor), I lean. On trips, I usually cruise above 8,000' at 140-150 kts and burning less than 7 gph.
 
Fixed pitch?......

So many of you say fixed pitch but never include what pitch the prop is. A 77" climb will be a whole lot different than a 80" cruise. Information is important!
 
Standard FP Sensenich Metal Prop

I ordered the "standard" Sensenich Metal Propeller from Van's. For 160 hp it is 79" pitch. Of course you can order climb (78") and cruise (81") from Sensenich directly. To make it more interesting, you can have fixed pitch propellers from other manufacturer too. So, whatever we put out here is just a reference based on one particular configuration.
 
Ted, that's it

That picture is exactly what I'm talking about. Doesn't it seem like if the elevator was perfectly in trail in your cruise profile the plane would go faster? At some reduced speed your elevator will likely be inline with the horizontal stab, at least mine is. In the past I've set up the throttle and mixture to cruise with the elevator in perfect trail and the plane was very stable. So with that said I simply don't understand setting the elevator to be down, or with the counter weights up? Is it to resist flutter kind of stable, or hold altitude kind of stable, or ??? I've seen my counter weights up as much a 5/8" in cruise before.

More pictures, please. This will be interesting. I think aircraft weight and cg will have some affect, but even so I'm curious if people claiming higher airspeeds have a more level elevator. While you folks have the camera out shoot pictures of your ailerons on both sides. Maybe we can catch some rigging trends or visual clues to make all of our birds behave like the faster ones. If we can get this going it will really be good information.
 
Bryan Wood said:
That picture is exactly what I'm talking about. Doesn't it seem like if the elevator was perfectly in trail in your cruise profile the plane would go faster? At some reduced speed your elevator will likely be inline with the horizontal stab, at least mine is. In the past I've set up the throttle and mixture to cruise with the elevator in perfect trail and the plane was very stable. So with that said I simply don't understand setting the elevator to be down, or with the counter weights up? Is it to resist flutter kind of stable, or hold altitude kind of stable, or ??? I've seen my counter weights up as much a 5/8" in cruise before.

More pictures, please. This will be interesting. I think aircraft weight and cg will have some affect, but even so I'm curious if people claiming higher airspeeds have a more level elevator. While you folks have the camera out shoot pictures of your ailerons on both sides. Maybe we can catch some rigging trends or visual clues to make all of our birds behave like the faster ones. If we can get this going it will really be good information.
Click to expand...

The horizontal stab can be shimmed, to put the elevator more in trail. However,

It's like the vertical stab and rudder. While later model RV's have an offset vertical stab, my short tailed 6A has no offset, but requires a rudder trim tab, which places the rudder at a small angle to the oncoming airstream.

So basically, my vertical stab/ rudder is exactly like the horizontal stab/ elevator in the picture.

So which causes more drag? A built in offset at the leading edge of the total assembly; or an offset at the trailing edge, controlled by trim tabs? Personally, I don't know! But I think it's almost sixes; as I compare my 6A to 7's and 8's around here. What I do know, is that moving the CG back, to where less down force is required on the horizontal stab, is the real key to more speed; but brings up possible stability problems.

edit: and BTW, my elevator counterweight is just like the one in the pic, in cruise. My ailerons are straight with the wing.

L.Adamson --- RV6A (flying)
 
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Bryan, another one on a 6A

Just came back flying with a friend in his 6A. The picture was taken at 6,500', 23" and 2,300 rpm cruising. I have no comments on speed/elevator position.

IMG_4505.JPG
 
flyinmonque said:
So many of you say fixed pitch but never include what pitch the prop is. A 77" climb will be a whole lot different than a 80" cruise. Information is important!
Click to expand...

I agree but the information is probably not of much value.
Every prop maker has there own means of measuring/designating pitch...effective pitch, pitch at a give span wise station, etc. A 77" pitch prop. from one manufacturer will often perform differently from a 77" from another manufacturer.
 
Bryan Wood said:
That picture is exactly what I'm talking about. Doesn't it seem like if the elevator was perfectly in trail in your cruise profile the plane would go faster? At some reduced speed your elevator will likely be inline with the horizontal stab, at least mine is.
Click to expand...

That would be the least drag condition but it is not possible to attain for more than one single flight condition. Just like your pitch trim changes with small changes in airspeed, this condition would also. It is only possible to have the elevators exactly in trail at one specific combination of C.G. position, TAS, and pressure altitude.
 
Bryan Wood said:
I think aircraft weight and cg will have some affect, but even so I'm curious if people claiming higher airspeeds have a more level elevator.
Click to expand...

Actually. the faster you go, more down elevator will be required to trim for level.
An airplane with positive pitch stability will act this way...nose will raise with speed increase...to maintain that speed it will require additional nose down trim.
 
rvbuilder2002 said:
Actually. the faster you go, more down elevator will be required to trim for level.
An airplane with positive pitch stability will act this way...nose will raise with speed increase...to maintain that speed it will require additional nose down trim.
Click to expand...
I agree. That is why the request for pictures. I'm wondering if the h stabs are shimmed differently on the fast planes to make the sweet spot at their cruise speed. It seems like the position of the counter weights might be a clue.
 
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Bryan Wood said:
I agree. That is why the request for pictures. I'm wondering if the h stabs are shimmed differently on the fast planes to make the sweet spot at their cruise speed. It seems like the position of the counter weights might be a clue.
Click to expand...

I don't know. Mine's awefully fast, and it looks just like that! :D

L.Adamson --- RV6A (flying)
 
L.Adamson said:
I don't know. Mine's awefully fast, and it looks just like that! :D

L.Adamson --- RV6A (flying)
Click to expand...

(Do you ever wonder why? I've flown with 180 hp 6A's that blow my doors off so badly that it hurts my feelings, and others that I can keep up with. I have no reason why.)


Frankly I don't have any idea if having the elevator in trail would make a big difference, or not at all. It would be interesting to set up power for a typical cruise and let the plane settle in. After checking airspeed and groundspeed slow down until the elevator is in trail with power reductions. Get everything all stable and take note of airspeed and groundspeed again. With the plane trimmed for this new condition put the power back to the higher cruise setting without retrimming. As the plane builds speed and gets heavy on the controls and just using muscle to overcome the out of trim condition would the speed be measurably different when you top out? I don't know but am curious. This would be kind of a backwards way of checking the concept even if it isn't accurate. Wouldn't it give a hint as to whether or not this has any merit? Again, I don't know. Then to confirm any difference the plane could be trimmed and checked again to see if the speed changes again. ???

Edit... Thinking more about this over dinner it seems like the travel of the trim tab might be a limiting factor on whether or not this could even be experimented with. George, Kevin Horton, or anybody else with a slide rule in their pocket that could shed some light on this topic?
 
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Bryan Wood said:
(Do you ever wonder why? I've flown with 180 hp 6A's that blow my doors off so badly that it hurts my feelings, and others that I can keep up with. I have no reason why.)
Click to expand...

My 6A blows the doors off the two 9A's I've flown with too. But then they get better fuel milage.........every time.

Oh..... and the 9 has it's elevator tip.......up, too! It varies with weight, according to owner. I've noticed that mine's up also, but haven't checked with different weight configurations.

L.Adamson
 
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Bryan Wood said:
(Do you ever wonder why? I've flown with 180 hp 6A's that blow my doors off so badly that it hurts my feelings, and others that I can keep up with. I have no reason why.)


Frankly I don't have any idea if having the elevator in trail would make a big difference, or not at all. It would be interesting to set up power for a typical cruise and let the plane settle in. After checking airspeed and groundspeed slow down until the elevator is in trail with power reductions. Get everything all stable and take note of airspeed and groundspeed again. With the plane trimmed for this new condition put the power back to the higher cruise setting without retrimming. As the plane builds speed and gets heavy on the controls and just using muscle to overcome the out of trim condition would the speed be measurably different when you top out? I don't know but am curious. This would be kind of a backwards way of checking the concept even if it isn't accurate. Wouldn't it give a hint as to whether or not this has any merit? Again, I don't know. Then to confirm any difference the plane could be trimmed and checked again to see if the speed changes again. ???

Edit... Thinking more about this over dinner it seems like the travel of the trim tab might be a limiting factor on whether or not this could even be experimented with. George, Kevin Horton, or anybody else with a slide rule in their pocket that could shed some light on this topic?
Click to expand...

Brian, I don't think this would show you anything useful. The only thing that would be different would be that the trim tab would not be deflected as much but you would still have to manually hold the elevators to virtually the same position as when the trim tab was doing it (there would be a very small difference because of the difference in effective elevator area with the trim tab a little closer to neutral than before). The speed change would probably be so small it would be very difficult to measure.
 
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