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Sufficient rudder with 180-200 HP

riseric

Well Known Member
Patron
Discussing with a pilot friend, he was concerned about my plan of having a IO-360 with 180HP in an RV-8. He was even surprised that 200HP were easily installed in these models.

His concern was on the take-off roll, with a tail wheel, the torque, the slipstream and the assymetric prop thrust would overwhelm the rudder and have the airplane swerve left despite full right rudder.

Obviously having not flown my plane yet, or any other RV, I can't answer him. So RV pilots out there, how is it???

Is the rudder "strong" enough to overcome all those forces on take off??

Or do you start the take-off roll with partial power and wait to have some airspeed before going all out??

Thanks

Eric
 
Discussing with a pilot friend, he was concerned about my plan of having a IO-360 with 180HP in an RV-8. He was even surprised that 200HP were easily installed in these models.

His concern was on the take-off roll, with a tail wheel, the torque, the slipstream and the assymetric prop thrust would overwhelm the rudder and have the airplane swerve left despite full right rudder.

Obviously having not flown my plane yet, or any other RV, I can't answer him. So RV pilots out there, how is it???

Is the rudder "strong" enough to overcome all those forces on take off??

Or do you start the take-off roll with partial power and wait to have some airspeed before going all out??

Thanks

Eric

It is and then some.
 
There is plenty of rudder to take off at full power in my 180HP CS RV, and I flew a friends 200HP and also plenty of rudder. It is a non issue.
 
Yeah, I think you can go on to worry about other things - 180 or 200 HP, I have never heard anyone say that the airframe doesn't have enough rudder. I certainly have never had a problme with this in any RV. You might find out if your friend has flown one.
 
I have a small tailed RV6 with around 200hp. Never felt that I needed more rudder. With the larger tail I can't see it ever being even a remote issue.
George
 
Yep, 200 HP here and not even close to an issue. Takeoff roll needs nothing more than just a bit of pressure, let alone actual displacement of the pedals. It's not a Merlin on the nose, for cryin out loud!
 
RV rudder

RV's are not known as rudder planes as Citabria's are. In 26 years of being around RV's, I have never heard a case of not having sufficient rudder.
 
I've got about 100 hours in a 192hp RV-8 and it needs much less right rudder on takeoff than does my 160hp RV-6. I have to put in lots more right rudder in my RV-6 to keep the ball centered and keep from drifting left off the runway centerline during takeoff than I ever did in the RV-8. The RV-8's rudder has an ample surplus of control authority.
 
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Not an issue!

Yep. What everyone says. It is not an issue. Ever.

Dan Miller
RV-8 190+ horsepower IO 360 M1; 1200+ hours
 
Eric,

Just to give you even more warm-fuzzy on this, there are several Super 8s with IO-540s flying with no rudder authority issues, and my Super 6, with an 8 tail and a stretched fuse that makes it similar in length to an 8, has no rudder authority issues either. 300+ HP, so that'll give an idea of the margin you'll have (plenty).

Have fun in your 8! :)

Cheers,
Bob
 
Thanks everyone for your time and replys!!!

I did a search on this before posting my question and didn't find anything relevant.

As I suspected, the rudder is plentyful and it's reassuring!!

I guess more power than 200 will create other issues, like forward CG, heat dissipation, bleeding ears because of a too high rate of climb, all runways looking too long etc... :rolleyes:

Thanks again!!!
 
What everybody else said.

Control authority in all three axes is excellent, much better than most GA airplanes.

This short clip might ease your friend's concern. It is a 200hp angle-valve RV-8 with a constant speed prop.
 
With all due respect, sounds like you've got a self appointed flying opinionator on your hands... I've come across them occasionally. They'll tell you about the design defects in the SR-71 and all about tricky flying, but are generally never observed performing said maneuvers. ;)
 
With all due respect, sounds like you've got a self appointed flying opinionator on your hands... I've come across them occasionally. They'll tell you about the design defects in the SR-71 and all about tricky flying, but are generally never observed performing said maneuvers. ;)

With all due respect, it's not the case as it was a genuisly curious question about aerodynamics vs power from someone that is highly regarded in the flying community. I think it was a very good question when one doesn't know the RV caracteristics. It still is a high performance engine in a relatively small plane...

Thanks to all for your inputs!!!
 
With all due respect, it's not the case as it was a genuisly curious question about aerodynamics vs power from someone that is highly regarded in the flying community. I think it was a very good question when one doesn't know the RV caracteristics. It still is a high performance engine in a relatively small plane...

Thanks to all for your inputs!!!

The question is understandable. In fact, we try to make the 8 models look like P-51's. They just don't have that P-51 rudder/power characteristic. Don't sound quite as good, either....:D
 
The question is understandable. In fact, we try to make the 8 models look like P-51's. They just don't have that P-51 rudder/power characteristic. Don't sound quite as good, either....:D

Yeah, we gotta find a way to get that P-51 engine and howling sound!!! :cool:
 
Super Six Rudder

I believe when the original builder, built Bob Mills' plane, it had the original RV6 small tail. Even with a 322 HP engine, I can't recall any issues. I have the same basic plane patterned after Bob's with an RV 8 tail with Zero issues.

Steve "the Builders Coach"
 
Wasn't Ol' Blue (or whatever Van's called the original RV-8) proofed with an angle valve, 200hp IO-360? Seems to me it was.
 
I believe when the original builder, built Bob Mills' plane, it had the original RV6 small tail. Even with a 322 HP engine, I can't recall any issues. I have the same basic plane patterned after Bob's with an RV 8 tail with Zero issues.

Steve "the Builders Coach"

That's correct Steve...both the 6 tail and the 8 tail had (have) plenty of authority.

Now, on the fun side, if we could find a way to get the power (and sound :cool:) of a Merlin in there, I'd happily learn the proper technique for adding throttle slowly on TO or GA ;) (though to be honest, I think the top end might be a little too scary...with any RV tail...in that case, eh! :eek:)

And FWIW, I see the original question as a bit of a compliment to RVs! :)

Cheers,
Bob
 
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