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RV-7 vs RV-8 aileron response

R

rv72004

Well Known Member
I flew the 8 a little bit the other day and it seemed to me the ailerons are lighter and roll quicker than the 7 . As this is the first in a 8 but have quite a bit of time in a 7 , I am still deliberating if it was my imagination.
I must say it really felt nicer than my 7. Was I imagining it ?
EJ
 
Center of mass

With two folks sitting in tandem (vs side by side) the center of mass will be closer to the roll axis. Seems like it should take less force to start/stop a roll.

MikeJ
 
I can't speak to a 7, but I have flown two different -6's in the past month, and was actually surprised at how light an nimble they felt in roll compared to my -8. Not that the -8 is heavy mind you....;)
 
rv72004 said:
I flew the 8 a little bit the other day and it seemed to me the ailerons are lighter and roll quicker than the 7 ...
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I wonder if the stick lengths are the same? A shorter stick is going to require higher forces.
 
Trailing edge radius on the aileron would probably have a bigger effect than probably anything else, right?
 
dan said:
Trailing edge radius on the aileron would probably have a bigger effect than probably anything else, right?
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Some trailing edges on dedicated aerobatic aircraft, are squared off. As if you ran a saw, and cut the last inch off.

L.Adamson
 
This isn't the 7 vs 8 comparison you were looking for ... but I agree with Paul.

When I took my 7A up for the first time after transitioning a week earlier in Pierre's 6A, I thought... WOW! This thing is a whole lot slower in roll! The stick forces to me are a whole lot lighter, especially in roll, when flying the 6A. Perhaps it's because of the slightly shorter wing?
 
Ahem...ahem...

Billy Waters had a 6 and now flies an 8. He has often told me that the 6 was a much better flier. BTW, I didn't shorten my stick any. The Van's pistol grips are at the same height as the original stick. Experienced RV fliers will, to a man, tell you that the -4 is the best flier of the bunch.

Thanks, Scott,
 
Yep!

Paul confirmed it, the -6A I had felt much quicker in roll than my -8. Although , if you get the CG back in the -8 by loading the rear, it helps the stick forces considerably. I can imagine that the -7 would be about like an -8 which is aft loaded. While still a great flying airplane, not quite as quick as a -6.
Kahana, you've flown all three, comments??
 
RV 6/7/8 differences

I have flown all three. Owned a -6 for years and over 155 hrs on the -8 and a few hrs in the -7.
When I first started flying the RV8, I noticed that it was heavier in the stick than the RV6 and RV7.
I think that the RV6 was lightest in control response across the board, the RV7 next and then the RV8. (Although different power and loading surely has some impact on this.)
In roll, I don't think it is that much different, but the RV6 seems to be lightest.
In pitch, the RV6 is definitely lighter on stick forces; however, as someone opined earlier, as the CG moves back on the RV8, they do get lighter.
In my opinion, the RV6 was the nicest handling, with the RV7 a very close second. The RV8 is dependent on how it is loaded....with a forward CG you get a heavier stick. On the RV6, the passenger and baggage weight stays closer to the spar, due to side by side seating, which works to keep it more nimble. (My opinion)
I also found the RV8 to be a little less forgiving in landings and it took a while to be able to consistently land it as well as I did my RV6.
Don't get me wrong, I love my RV8, but there are differences between the different RV types. (Still looking forward to trying on an RV9!)
 
Can someone clear this up for me?
If loading about the axis of rotation is neutral (no heavy wing and/or c.g. which requires elevator input) and speed is constant, aren't stick forces primarily a function of:
1. Control surface area and center of effort on outboard end.
2. Length of control stick and hand position on the other?

Isn't roll rate measured at full control deflection regardless of stick force?
I would think it would be more a function of wingspan and control effectiveness.

Any aeronautical engineers or test pilots out there with a non-subjective answer?
Thanks,
Terry
 
terrykohler said:
Can someone clear this up for me?
If loading about the axis of rotation is neutral (no heavy wing and/or c.g. which requires elevator input) and speed is constant, aren't stick forces primarily a function of:
1. Control surface area and center of effort on outboard end.
2. Length of control stick and hand position on the other?
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These two things cause some of the difference. I believe there are also others.

The ailerons on an RV-6 are smaller in span than they are for a 7 or 8.
When the 6 was orig. designed, the wing span remained the same as a 4, but the wing panels were slightly smaller because of the wider fuselage between them. The flaps were made (mostly) the same size as those on the 4 so the panel size difference was accounted for in a change to the aileron.
The RV-8 (and then 7) got a wing panel that is basically the same size as the RV-4. I think the surface area accounts for a lot of the stick force difference but not all of it.
The RV-7 and 8 also have totally different style aileron bell cranks which I believe accounts for a slight change in stick force. Add in stick length differences and other variations of the control system and you get a noticeable difference between the models.


Between the RV-6,7, and 8, my favorite also is the 6.
 
pierre smith said:
Billy Waters had a 6 and now flies an 8. He has often told me that the 6 was a much better flier. BTW, I didn't shorten my stick any. The Van's pistol grips are at the same height as the original stick. Experienced RV fliers will, to a man, tell you that the -4 is the best flier of the bunch.

Thanks, Scott,
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Yes.
Absolutely.
And not just because I fly one. :)

I think it's a "grass is greener" thing. Two other EAA chapter members each have an RV-8 and an RV-6A. Both their ailerons seem lighter to me.
 
pierre smith said:
Billy Waters had a 6 and now flies an 8. He has often told me that the 6 was a much better flier. BTW, I didn't shorten my stick any. The Van's pistol grips are at the same height as the original stick. Experienced RV fliers will, to a man, tell you that the -4 is the best flier of the bunch.

Thanks, Scott,
Click to expand...
Sounds like these "experienced RV fliers" haven't flown the -3. Everyone I know of that has flown the -3 thinks it is the best.
 
The -3 experience!

Everyone I know of that has flown the -3 thinks it is the best.
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Heard the same thing! Helping a friend complete a -3, looking forward to flying it!
 
Mel said:
Sounds like these "experienced RV fliers" haven't flown the -3. Everyone I know of that has flown the -3 thinks it is the best.
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The original 3 had a fuselage tank; the 3B has two 15 gallon wing tanks. Does anyone have any experience with the two different configurations? I wonder if the wing fuel noticeably changes roll characteristics.
 
Hooray for the 6!

My builder assist man Noel Simmons says the 6 is more nimble than the 7. Hooray for the 6!. He has built like 20 RV's.

Hans
 
Stephen Lindberg said:
The original 3 had a fuselage tank; the 3B has two 15 gallon wing tanks. Does anyone have any experience with the two different configurations? I wonder if the wing fuel noticeably changes roll characteristics.
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All of the -3s I've flown have had the wing tanks, so I can't compare the fuselage tank. But every one I've flown has performed better than any other RV I've flown. BTW, many of the straight -3s and -3As have been converted to wing tanks. I won't fly a -3 unless it's had at least the -A mod.
 
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I have flown them all, except the 12. My 2 cents below.

The 3 is NOT better in roll. In fact its as bad as the 8. What the 3 has is super tight pitch capibility, loops done in 300'. Its light and fun. Roll rate is high, but roll force is also high. I was not particularly pleased with the 3 in roll, but man will it loop like right now. If your doing a little ACM with your buds, the 3 cant be beat. It will out turn, climb and roll any of the others with a 160 sench FP. Its pretty cool. But would not be my first choice for overall best feel.

The 6 has the best roll feel in force. But not the best rate. I have a couple hours in a 6 and 8. The 6 handles better than the 8 in all aspects of handling capibility. But the center axis of the 8 is more pleasurable in handling.

The 4 is best best all around for feel in force and rate in pitch and roll. It is my choice for "handling".

The 9.. Well its ok for what it is. Still cant for the life of me figure out why people are byuilding these, but they are.

The 10 is fun, but its of course outside the bounds of these handling discussions. Vis is good, room is great. Its going to really smack this market silly up side the head.

The 12.. Your not getting me in that ugly looking thing.

Done with my 2 cents.
Best
 
Kahuna's dead on. All points.

I've talked to Ken Krueger many times about the differences between the -3 and the -4 and it is his experience that a -4 flown solo with the same powerplant/prop is more manueverable than a -3 ......due primarily to its different airfoil and different wing loading.

If I build again someday (and I probably will) it will be a -4. Fastback. Super simple/light - compass from Wal Mart on dash. Manual everything. Day VFR fighter. Cheap as possible so I can maybe keep the -6 for travelling.

If you need to find me, I'll be the guy on your six.;)

b,d

-6's rock. -4's rule.
 
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If I build again someday (and I probably will) it will be a -4. Fastback. Super simple/light - compass from Wal Mart on dash. Manual everything. Day VFR fighter. Cheap as possible so I can maybe keep the -6 for travelling.
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Doug, just find an old, clapped out -4, throw away the engine, panel and back seat, strip the paint, and you have a -4 super quick-build. :)

I have entertained similar thoughts as yours.
 
DeltaRomeo said:
Kahuna's dead on. All points.

I've talked to Ken Krueger many times about the differences between the -3 and the -4 and it is his experience that a -4 flown solo with the same powerplant/prop is more manueverable than a -3 ......due primarily to its different airfoil and different wing loading.

If I build again someday (and I probably will) it will be a -4. Fastback. Super simple/light - compass from Wal Mart on dash. Manual everything. Day VFR fighter. Cheap as possible so I can maybe keep the -6 for travelling.
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Like Mel, everyone I've talked to who has flown them all say the -3 is best overall, and by a fair margin. Kahuna, maybe the ailerons on the -3 you flew were oversqueezed? That will have a surprising effect as Checkoway mentioned earlier in this thread.

On that point, a local guy recently flew his -3B after having sold his -8A. He reported that it felt heavy in the ailerons by comparison but that he had squeezed both ailerons chasing a wing heavy. I talked to him a week later and he said he fattened both ailerons up and it became way lighter in aileron feel. Just goes to show you how sensitive they are. My ailerons are QB and look a bit fat so I intend to leave 'em that way.

I feel kind of stupid at this point, I've spent relatively big $ and three years building what I consider the ultimate -3 yet have never flown one. I guess I'll find out within a few weeks though for better or for worse, that is if I ever get my prop back!

BTW Doug, the airfoil is the same on the -3 and -4 but the -4 is 13.5% thick whereas the -3 is 12% thick, further info here. Indeed wing loading would be less on the -4 when flown solo... 90 sq.ft on the -3, 110 sq.ft on the -4, but then again a -3 will typically be around 200-225 lbs lighter. Hmm, guess we'll just need to do some dogfighting and find out... ;-)
 
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