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RV-9 /9A aerobatics

MacCool

Well Known Member
I have no desire nor intent, but I’m curious as to what it is that makes the RV-9 and 9A limited to non-aerobatic flight. Is it the Roncz airfoil? Is it a handling/control issue, or a structural issue? Is the 9/9A somehow less robust than the 7/7A?
 
Given the similarity of the fuselage to the -7, I would guess that the wing and tail structure were not designed to take the flight loads of aerobatic flight to the aerobatic standard limits.

That said, many people have looped and rolled their -9's. They just had a lot less safety margin that someone in a -7 would. When things go sideways, you want that margin.
 
Yes

It is the strength of the wing. The 9a wings are longer span and narrower, giving better high altitude performance at the sacrifice of a lower maximum g load. The wing is slipper due to the higher aspect ratio. If you screw up the maneuver in a 9, you could pull the wings off.
 
I thought I'd understood that the 7 and the 9 had the same fuselage and empennage, so that makes sense - wings not stressed for G loads associated with (incorrectly) performed aerobatics. I presume that it's not something I have to worry about in non-aerobatic flight as long as I pay attention to the maneuvering speed....?
 
Still 6 gs

If I am not mistaken the RV9 is still designed for 4.4 gs.(corrected, see below) I think I will be passed out before the plane comes apart, so I am not worried.
Most of our wonderful ex-military pilots can pull 9 gs all day long, they are the ones the 9 will complain about.
 
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If I am not mistaken the RV9 is still designed for 6gs. I think I will be passed out before the plane comes apart, so I am not worried.
Most of our wonderful ex-military pilots can pull 9 gs all day long, they are the ones the 9 will complain about.

Are you sure? I thought it was utility category up to 1600lbs. That's +4.4G/-1.75.

Besides, anyone who skis a pair of downhill mogul churning skis , and then slips on longer, skinny skis for cross-country understands what a difference that longer wing will make.

Its not about doing it right. Its that one time you don't that'll get you.
 
If I am not mistaken the RV9 is still designed for 6gs. I think I will be passed out before the plane comes apart, so I am not worried.
Most of our wonderful ex-military pilots can pull 9 gs all day long, they are the ones the 9 will complain about.

RV-9(A) are stressed to utility category +4.4/-1.76 G at solo weight and normal category +3.8/-1/52 G at gross weight. The aerobatic aircraft -3,-4-,-6,-7,-8 are stressed to aerobatic category +6/-3 G (but not sure at what weight). Very dangerous to assume a higher limit load factor than the designer used.
 
SNIP I think I will be passed out before the plane comes apart, so I am not worried. SNIP.

This is not true. You would still be awake to see the wings break. The airplane does not care how short the duration of the g-event is, while your body does. The sticks in all RV's are very capable wing-removal levers. Pull the stick too fast and too much, and you're toast.
 
I thought I'd understood that the 7 and the 9 had the same fuselage and empennage...

There are differences in the Horizontal Stabilizer and Elevators. The 9 has a rectangular shape, and the 7 has a swept leading edge. Fuselages are 99% the same, save for the forward attachment of the wing due to the different shapes.
 
Guess

If I were to guess, I suspect the high aspect ratio wing performs less optimal pulling G’g than the other standard Vans wings. I also suspect the longer span, and the longer horizontal are less tolerant to g loading than the other van designs. Sure, you can perform whatever acrobatic you prefer, however, you didn’t purchase enough margins in this design to be able to do multiple aerobatic maneuvers such as tail slides and live to tell about it. As a matter of fact, some of the other designs don’t have enough margins for tail slides so I guess every design has its aerobatic limitations. A good aerobatic pilot such as Bob Hoover could do a lot of non stressful aerobatic maneuvers in any plane so it really comes down to skill and acceptable risk.

I have no desire nor intent, but I’m curious as to what it is that makes the RV-9 and 9A limited to non-aerobatic flight. Is it the Roncz airfoil? Is it a handling/control issue, or a structural issue? Is the 9/9A somehow less robust than the 7/7A?
 
The spar is the same on the 7 and 9 except for its length. Torque a bolt with a stubby wrench some day and then do it with the longer wrench. You will soon see that you can exert far more torque with the longer wrench. It’s the same with the wing. Any lift created at the end of the 9 wing exerts far more twisting action than the shorter wing of the 7.

The 9 wing is designed for efficient climb and higher altitude cruise speed. I love mine for cross country. I will maybe try to get some aerobatic training in my next plane Rans s21. It’s rated at 6 g. A very experienced pilot, whom I trust implicitly regarding aero, told me to get aerobatic training in a far less slippery airframe than a vans rv.I’m taking his advice.
 
The spar is the same on the 7 and 9 except for its length. Torque a bolt with a stubby wrench some day and then do it with the longer wrench. You will soon see that you can exert far more torque with the longer wrench. It’s the same with the wing. Any lift created at the end of the 9 wing exerts far more twisting action than the shorter wing of the 7.

The 9 wing is designed for efficient climb and higher altitude cruise speed. I love mine for cross country. I will maybe try to get some aerobatic training in my next plane Rans s21. It’s rated at 6 g. A very experienced pilot, whom I trust implicitly regarding aero, told me to get aerobatic training in a far less slippery airframe than a vans rv.I’m taking his advice.

That is sound advice!!!
 
The spar is the same on the 7 and 9 except for its length. Torque a bolt with a stubby wrench some day and then do it with the longer wrench. You will soon see that you can exert far more torque with the longer wrench. It’s the same with the wing. Any lift created at the end of the 9 wing exerts far more twisting action than the shorter wing of the 7.

The 9 wing is designed for efficient climb and higher altitude cruise speed. I love mine for cross country. I will maybe try to get some aerobatic training in my next plane Rans s21. It’s rated at 6 g. A very experienced pilot, whom I trust implicitly regarding aero, told me to get aerobatic training in a far less slippery airframe than a vans rv.I’m taking his advice.

So with that said, just arm chair thinking I wonder if someone could do a clipped wing 9. HMMMM...
 
Wing tips

You could remove the big wingtips and put end plates on and save some wingspan but anything more would be extensive because the flaps and ailerons would have to be shortened. The wingtips have some efficiencies built in with those outer tips moving the wing vortexes away so you may end up with no net gain. Who knows.

So with that said, just arm chair thinking I wonder if someone could do a clipped wing 9. HMMMM...
 
no aerobatics

like others I've been temped to do aerobatics in the 9 but so far I have resisted. no rolls or loops. I hope I can continue to resist. if the 9 had been designed for aerobatics I would do them but since it was not I don't. simple as that.
 
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Just to throw a log on the fire.

The 9 cannot do advanced aerobatics, but you can roll just about anything...RV9A or a Boeing 707 if you stay at 1G. The plane doesn't know up from down as long as you maintain that 1G. The 9A has a better roll rate than a lot of airplanes which are rated for aerobatics.

Just sayin'...:D

3.2.1...begin flaming.

https://photos.app.goo.gl/h8feirnUvasoByGB9

https://photos.app.goo.gl/SvYPfa72QEboQR9J8
 
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If I had an RV-9 and I wanted to do acro, I would certainly put it on a video for my Insurance company to see. It would probably help with my rates to show how good I fly.
 
When I saw the thread title, I started a big batch of popcorn before I even opened the thread.
 
Aircraft capability and safety notwithstanding, I note that my insurance does not cover any flight that exceeds the Operating Limitations on my Airworthiness Certificate. Which excludes aerobatics on my RV-9A.
 
Spar

The spar is the same on the 7 and 9 except for its length.

This is incorrect. The 9 wing is thicker and the spar is taller then the -7. The -9 fuselage has a different center section than the -7 to accommodate the different wing spar.

Skylor
 
Skylit
I thought they where the same thickness. I used blocks from a 7to space my centre section during the build and I did not notice any height difference. If the 9 is higher it only reinforces the extra torque math
 
today was broken clouds in Cincy around 3PM and only 500 ft thick. cruising underneath at 2900 ft and 140 kts I saw a hole and pulled up. I glanced at my rate of climb, 3500 ft/min, and about that time I was above the clouds and climbing rapidly at a nice angle. visions from Top Gun flooded my brain. not aerobatic, but Wow! I ascended to a different world of beauty.

I collected some engine temp data for OAT = 1C with 1 inch wide cowl inlet air dams installed. CHTS were within 10F of each other and my oil temp was 174F. CHT average = 320F at 4.5K ft. EGT as always, 1300F, at this low altitude.
 
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