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Difference between 7A and 9A

I?m sure this has been asked..... but is the only difference between the -7A and -9A being the -7A is aerobatic and the engine you can install?
 
I think the above link addresses the fact that building a 7 or a 9 are very similar in tasks & effort.

These are the 9 vs 7 differences I can think of at the moment, undoubtedly others will think of more.

Although they both look very similar, there are a number of differences in design that define each model's individual 'mission'.
They have different airfoils - 23013.5 vs Roncz RV6T giving different flight characteristics. The wingspan is longer & cord narrower on the RV-9 giving better glide ratio, & probably narrower CofG range. Slotted flaps are used on the RV-9 compared to plain flaps on the 3/4/6/7/8, over 63% of the wingspan compared to the 52% on earlier models. These wing changes greatly reduces stall speed to even slower than the later light weight RV-12. The smaller ailerons, though very responsive are dampened compared to the prior models, probably more suited to it's 'mission'.
Larger surfaces were used on the tail section again suited to it's mission, the squarish horizontal and slightly larger elevators for more positive response. Rudder & vertical surfaces are similar to other models, maybe the earlier sizes were sufficient to carry over into the RV-9 'mission'.
Landing gear is a bit different too. The nose gear leg is common between the 6/7/9 but the geometry is slightly different. The main legs progressively get longer from the 6 to the 7 & a bit longer on the RV-9, pushing the ground stance on the RV-9 more tail high & promotes a better stance for LANDING ON THE MAINS.
Suprisingly the engine position is slightly different between the 6/7 & RV-9 (I had to measure twice) with the engine being just over an inch farther forward of the firewall compared to the previous models. This must accommodate the lighter 320 engine weight versus engines commonly installed on the 6/7 models, and the narrower CofG window on the RV-9.
There are performance differences, yes, but are suited to it's 'mission'.
The RV designs are progressive, as a number of basic '9 components have made their way into the 14's too.
 
I think we are the only ones that I'm aware of that have regularly flown air shows with the -9A with Falcon Flight, and I would say, down low, after you deal with the -20HP, the biggest real difference is roll rate. Pitch is darn near exactly the same.

On the down line, as the speed builds, the -7 ailerons remain quite snappy, whereas the -9 ailerons become quite stiff / forces go way up in roll. I quite often use my legs automatically to augment the roll stick forces. I'm not talking about a roll maneuver, but the aileron forces to simply stay in position.

Then, when coming down the ILS at night when it is raining and am asked to "keep the speed up", No problem, we're on rails.
 
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CG calcs

Here is a link to flight manual for a RV-9A, it includes sample weight and balance calcs that will give you an indication of what can be carried.

https://9edd576d-7080-453e-9fa9-e5b...d/ef09ad_85cf427e4d2743bdb2c743cd16867254.pdf

From a pilot's perspective, perhaps the most noticeable difference between a -7A and a -9A is that the 9A tends to float when landing, so speed control is critical. The float is due to the efficient wing and the low drag airframe, as others have mentioned.
 
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My -9 taildragger tip-up came out at 990 lbs for its first flight. This left me 760 lbs useful load. There was almost no way to get it out of CG, even with 100 lbs in back.

I don't have my manual and don't know the CG range of the -7 but it wouldn't surprise me if the CG range is very close. The larger HS on the -9 will help with the CG range as well as reduce the pitching moment caused by the slotted flaps.

The -9 and -7 share the same fuselage VS, and rudder as the -7.

If you compare the 160 up -9 to the 160 hp -7, you will see the -9 has a shorter takeoff and landing distance and better ROC.

It is pretty much the same effort to build either, so no issue there.

On final, the -9 approaches at speeds the will see -7 will fall out of the sky.

Scott is right, the -9's ailerons do get stiff; however, the -9 has better balanced controls than the short wing RV's.
 
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Scott is right, the -9's ailerons do get stiff; however, the -9 has better balanced controls than the short wing RV's.

All in the hand of the beholder I guess......

It think it depends on the ideal mission you are basing that statement on.
Cross country cruiser / IFR platform and the 9,10 and 14 are all quite similar, and very well tailored to that role.

If just being judged on pure fun to fly handling I think most people that have quite a bit of time in all the models would say the true short wing (6,4 & 3) are the most fun / balanced feeling, with the RV-3 being the all time winner.

BTW, the 9/9A doesn't float any more than any of the other models will unless it is not on the proper speed for landing (and that can be said for all the models)
 
BTW, the 9/9A doesn't float any more than any of the other models will unless it is not on the proper speed for landing (and that can be said for all the models)

Scott is the expert but I will say this. The high-aspect wing on the -9 does not, in my free opinion, retain the energy that the wing on the -3 thru -8. What I could do in the -3,-4,-6,-7,-8 as far as loading the during the landing phase will not work with the -9 as the accelerated stall characteristics are different. Yes the -9 will land slower, but that will will bite if you load it up. Same with the other models but they seem to be a little bit more forgiving. Just my opinion and I?m not taking anything away from the -9 as I agree with many people that the -9 is the best kept secret in the Vans stable.
 
Something I've never seen addressed is crosswind handling. Does the longer wing and smaller aileron on the -9 make it less crosswind-capable? The -7 is one of the best crosswind airplanes I've ever flown.
 
Scott is the expert but I will say this. The high-aspect wing on the -9 does not, in my free opinion, retain the energy that the wing on the -3 thru -8. What I could do in the -3,-4,-6,-7,-8 as far as loading the during the landing phase will not work with the -9 as the accelerated stall characteristics are different. Yes the -9 will land slower, but that will will bite if you load it up. Same with the other models but they seem to be a little bit more forgiving. Just my opinion and I?m not taking anything away from the -9 as I agree with many people that the -9 is the best kept secret in the Vans stable.

I am always interested in what other pilots think of the airplanes, but in this case Craig, I am not understanding what you are talking about.

My comment was in regards to tendency to float during landing. Loading beyond 1 G and the resulting stall characteristics wouldn't even be part of the landing equation.

Confused.........
 
Clarification

The -9 wing in my experience has a different response when it?s loaded as opposed to the other designs. I?m not diminishing your comment about floating as I agree with that. My point is that even though it can be a floater due to its efficiency, and even though it?s got a great low stall speed, it doesn?t carry the energy when loaded like the others (1g or whatever). Aeronautical engineers know this as common knowledge concerning the high aspect wings. However, a new feller may not be aware. Heck, he may never know and think all wings are the same. I was just making a general comment about the differences.
 
it's all about the wing for the -9. designed by some amateur. John Roncz is a self-taught genius aerodynamicist who, among other things, designed the airfoils (wings) and propellers for virtually all of Burt Rutan's aircraft designs.
 
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My point is that even though it can be a floater due to its efficiency, and even though it’s got a great low stall speed, it doesn’t carry the energy when loaded like the others (1g or whatever). Aeronautical engineers know this as common knowledge concerning the high aspect wings.

Actually, the opposite is true.

It's not so much "loading it up" but rather L/D at higher angles of attack. And, all else being equal, higher aspect ratio wings will have *less* drag (specifically, lift-induced drag) at high AoA than will lower aspect ratio wings. But all else is not equal here; there is a different airfoil present on the 9 and it's almost certainly not optimized for high alpha manuvering given the stated mission of the design. Perhaps that factors in - but it's certainly not aspect ratio that would be causing the behavior you describe.
 
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Something I've never seen addressed is crosswind handling. Does the longer wing and smaller aileron on the -9 make it less crosswind-capable? The -7 is one of the best crosswind airplanes I've ever flown.

Basically, yes, but not for the reason you stated, if I've got my facts straight. One problem is that, in general, the slower the landing speed, the less crosswind capability the plane has. (Crosswind capability = sin (sideslip angle) * speed. So the slower landing speed of the -9/A doesn't help in that regard.

The other problem is that if you try to add speed for the wind like you do in other airplanes, the -9/A will float in the flare till it finally settles down. I haven't measured it since I added the constant speed prop, but with the fixed pitch prop, 5 knots extra would be good for two seconds more float.

And then there's weathervaning tendency as you slow down. I don't have and don't want experience with this phenomenon in really strong crosswinds, but I don't think the -9/A would be any worse than the -7/A. I know that when I had the AirCam, it was a real pain to taxi when the winds got over 10 mph because the vertical fin was so big. It had to be that big to let you keep control of the airplane, single engine, at all flying speeds. Differential thrust helped only a little....

For all its other virtues, I think the -9/A is satisfactory in crosswinds, but not great. Then again, there's lots and lots of control authority in the flare in all three axes, and that helps.
 
Actually, the opposite is true.

It's not so much "loading it up" but rather L/D at higher angles of attack. And, all else being equal, higher aspect ratio wings will have *less* drag (specifically, lift-induced drag) at high AoA than will lower aspect ratio wings. But all else is not equal here; there is a different airfoil present on the 9 and it's almost certainly not optimized for high alpha manuvering given the stated mission of the design. Perhaps that factors in - but it's certainly not aspect ratio that would be causing the behavior you describe.

Absolutely correct.

If there is one attribute of the early short wing RV models that takes some pilots a while to get used to is the strong influence of high induced drag at higher angles of attack.
As angle of attack increases, induced drag goes up dramatically. This is what has caused damage of quite a few short wing RV's over the years.

With the fantastic control response that RV's have, pilots can be lulled into feeling comfortable on approach at a speed that they feel fully in control (because the airplanes still have great control response even at very low airspeed) but is way too low to have enough energy to arrest the higher than normal rate of decent. The result is usually damaged landing gear or worse. This happens because there is no reserve energy for the round-out / flare, and as soon as the AOA is increased, what small amount of reserve energy/airspeed is left, goes away very quickly.

This is also the reason that short wing RV's don't do as well as they could in a race situation like Reno. The wing is constantly "loaded up" with G's (needing to fly at a higher AOA) and having a resultant higher induced drag than would be the case in un-accelerated flight. (this is likely the primary reason for the work being done by some to develop a tapered higher aspect ration wing).

The RV-9 has a much higher aspect ration wing so it has less of a tendency for the induced drag to increase with AOA. This is likely what makes it seem to some pilots that it will float forever compared to the short wing models.
If the amount of over speed on an aproach is the same for an RV-6A and an RV-9A... say 10 knots.... I guess the 9a would be perceived to float longer (its lower induced drag increase will make it take longer for the speed to be scrubbed off). I think this is what makes people think it is more of a floater than the short wing airplanes
But, since the stall speed is lower on the 9A, if an RV-6A and an RV-9A were fast by the same percentage, I feel that the amount of float would feel to be about the same.

Regardless, the important thing to make proper landings is to be on the proper airspeed. If that is followed, long floaty landings should never be a problem.
 
-9A in crosswinds

I think this is right. The -9A seems a lot like my old Warrior when it comes to handling crosswinds. A bit more susceptible to gusts due to the light weight.

For all its other virtues, I think the -9/A is satisfactory in crosswinds, but not great. Then again, there's lots and lots of control authority in the flare in all three axes, and that helps.
 
Something I've never seen addressed is crosswind handling. Does the longer wing and smaller aileron on the -9 make it less crosswind-capable? The -7 is one of the best crosswind airplanes I've ever flown.

It probably is slightly less capable when compared to an RV-7, but still way more capable than most of the certificated airplanes that most people are accustomed to flying.

Way back in the days where I flew Cessna's and Pipers, it was fairly common that in strong, particularly gusty cross winds, to be hitting the control stops on the ailerons. Since for most normal flight we are rarely using more than 10% of the control input, that just doesn't happen with RV's. Even the RV-9.

I have always felt that this attribute is what makes RV's (in my opinion) much easier to land in gusty crosswind conditions compared to all of the certified airplanes I have flown...... there is a lot of excess control margin beyond what is needed for just normal maneuvering.
 
Something I've never seen addressed is crosswind handling. Does the longer wing and smaller aileron on the -9 make it less crosswind-capable? The -7 is one of the best crosswind airplanes I've ever flown.

Basically, yes, but not for the reason you stated, if I've got my facts straight. One problem is that, in general, the slower the landing speed, the less crosswind capability the plane has. (Crosswind capability = sin (sideslip angle) * speed. So the slower landing speed of the -9/A doesn't help in that regard.

The other problem is that if you try to add speed for the wind like you do in other airplanes, the -9/A will float in the flare till it finally settles down. I haven't measured it since I added the constant speed prop, but with the fixed pitch prop, 5 knots extra would be good for two seconds more float.

And then there's weathervaning tendency as you slow down. I don't have and don't want experience with this phenomenon in really strong crosswinds, but I don't think the -9/A would be any worse than the -7/A. I know that when I had the AirCam, it was a real pain to taxi when the winds got over 10 mph because the vertical fin was so big. It had to be that big to let you keep control of the airplane, single engine, at all flying speeds. Differential thrust helped only a little....

For all its other virtues, I think the -9/A is satisfactory in crosswinds, but not great. Then again, there's lots and lots of control authority in the flare in all three axes, and that helps.

My comment about the-9 handling better than the short wing RV's has to do with control balance, not overall lightness. The short wing RV's tend to be overly pitch sensitive in relation to the roll axis.

As for crosswinds, how much of a crosswind are you willing to take on?

As for crosswind landings...
I once landed my taildragger -9 in a 32 knot direct crosswind, much to the surprise of the controller. As I taxied off the runway, he told me he had his hand on the crash button, waiting for me to ground loop.

If the short wing RV's can do better, outstanding.

The -9 has a longer flap and it is a slotted flap design, unlike the flaps on the short wing RV's. The flaps are part of the equation for the -9's low landing speed.

As Scott mentioned, if you are on speed, landing is not an issue; however, if you come in too fast, you can float a long way before the wing is done flying.

It is not uncommon for me to turn off at midfield on our 2400' runway without using the brakes.
 
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Good explaination

Good post Scott. This clarified a lot to me and should be good info for prospective pilots. I loved my -3 and -6 but really like the -9. It just took me some getting used to as the wings respond a tad different when loaded up during the round out. It?s not a negative by any means.


Absolutely correct.

If there is one attribute of the early short wing RV models that takes some pilots a while to get used to is the strong influence of high induced drag at higher angles of attack.
As angle of attack increases, induced drag goes up dramatically. This is what has caused damage of quite a few short wing RV's over the years.

With the fantastic control response that RV's have, pilots can be lulled into feeling comfortable on approach at a speed that they feel fully in control (because the airplanes still have great control response even at very low airspeed) but is way too low to have enough energy to arrest the higher than normal rate of decent. The result is usually damaged landing gear or worse. This happens because there is no reserve energy for the round-out / flare, and as soon as the AOA is increased, what small amount of reserve energy/airspeed is left, goes away very quickly.

This is also the reason that short wing RV's don't do as well as they could in a race situation like Reno. The wing is constantly "loaded up" with G's (needing to fly at a higher AOA) and having a resultant higher induced drag than would be the case in un-accelerated flight. (this is likely the primary reason for the work being done by some to develop a tapered higher aspect ration wing).

The RV-9 has a much higher aspect ration wing so it has less of a tendency for the induced drag to increase with AOA. This is likely what makes it seem to some pilots that it will float forever compared to the short wing models.
If the amount of over speed on an aproach is the same for an RV-6A and an RV-9A... say 10 knots.... I guess the 9a would be perceived to float longer (its lower induced drag increase will make it take longer for the speed to be scrubbed off). I think this is what makes people think it is more of a floater than the short wing airplanes
But, since the stall speed is lower on the 9A, if an RV-6A and an RV-9A were fast by the same percentage, I feel that the amount of float would feel to be about the same.

Regardless, the important thing to make proper landings is to be on the proper airspeed. If that is followed, long floaty landings should never be a problem.
 
Best crosswind I've done in my 9A was 25-26 knots direct cross, and I still had some rudder left for more, but haven't attempted any more than that. Taxiing with that much wind in the 9A is more difficult than landing it.
 
My comment about the-9 handling better than the short wing RV's has to do with control balance, not overall lightness. The short wing RV's tend to be overly pitch sensitive in relation to the roll axis.

Interesting. Compared to the short wing RVs, I find the -9 to be overly sluggish in roll compared to the pitch axis :cool:
 
My brother has a -9A, my friend had a -7A, both in my hangar. The deal for them keeping them in my hangar is I get to fly them whenever I want to.

I had more time in the 9 than the 7, but I felt like I did a better job of flying the 7 than the 9. The -9A has an O 320, FP. The -7A had an IO 360 CS.
 
It probably is slightly less capable when compared to an RV-7, but still way more capable than most of the certificated airplanes that most people are accustomed to flying.

Yes, for sure. It's no contest when compared to the 172s and Cherokees I've flown as rentals.
 
Scott has described my experience as well, I have over 100 hours in 9?s but not within the past 5 years. All of my recent experience has been in my 7. I am more proficient and comfortable In my tail dragger 7 then certified tricycle gears in crosswinds, about 20 knots xwind in a certified trike and 25 knots in the 7.

My 7 will carry 2 200lb passengers, 100lbs of baggage and full or empty tanks and never exceed the CG, aerobatics it?s me (180lbs) a 200 lb pass and 23 gallons. It?ll carry more but I?ve got to run the numbers.

IFR would be better in the 9, I still prefer my 7 over a certified airplane because it is equipped better and I?m more proficient in the 7.

I took my demo ride at OSH in Van?s 9, almost ordered it several times. I almost ordered the 8 several times as well, I wouldn?t have been disappointed with or regretted any of them. I decided I wanted the aerobatic option of the 7 or 8 vs the IFR/XC stability and up high efficiency of the 9, I wanted the side by side option of the 7 to teach my (not even conceived at the time) kiddos to fly. Trade offs for you to decide which one fits your mission better, they?re all great!
 
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