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  #1  
Old 10-31-2017, 01:35 PM
fbrewer fbrewer is offline
 
Join Date: Sep 2017
Location: Leander
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Default Forward Stick Authority on takeoff RV-6

Members,

I finished my tailwheel endorsement in a Super Cub two weeks ago. So now that I have 6.5 hours of TW time, I am obviously an expert.

In the cub, the takeoff procedure was stick full aft for two seconds, and then take 3-4 second to go full forward on the stick and hold it there. The tail would raise, but would not raise further than approximately level flight.

I was surprised that it really was generally not possible to raise the tail too far and have a prop strike.

My question in the RV-6 is this: if I go full forward on the stick in the RV-6 and hold, will the tail continue to rise as speed builds and eventually cause a prop strike?

Or is the design of the RV-6 such that full forward stick on a normal takeoff (no gusting winds), will not cause a prop strike?

TIA
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  #2  
Old 10-31-2017, 01:49 PM
rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by fbrewer View Post

My question in the RV-6 is this: if I go full forward on the stick in the RV-6 and hold, will the tail continue to rise as speed builds and eventually cause a prop strike?
I don't know, because for a normal take-off (lifting the tail as you have described) doesn't take anywhere near full fwd stick.
My guess is that about 1/2 nicely lifts the tail to a just slightly tail low attitude.
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  #3  
Old 10-31-2017, 02:10 PM
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flyr747 flyr747 is offline
 
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TIA,

During takeoff in my RV-6 I hold the stick lightly in a neutral position and as I slowly advance the power the tail will gently rise off the ground within a few feet. At that point you can feel the elevator come alive and I increase the forward pressure slightly to attain a more level attitude. A few feet later with flying speed the plane becomes airborne.

I would strongly discourage holding full forward stick on takeoff as the elevator authority is probably sufficient to cause a prop strike or at least an unsafe nose down attitude while on the ground. Another possibility is the tail would come off the ground very quickly causing the pilot to over compensate with aft stick slamming the tail wheel back into the ground causing damage.

Overall, the RV-6 is much more responsive to pitch controls than a Super Cub and these large inputs on takeoff are not necessary. Within a few hours you will appreciate the difference.
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  #4  
Old 10-31-2017, 02:10 PM
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Sam Buchanan Sam Buchanan is offline
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There is also no reason to raise the tail to the point where the fuselage is horizontal. Takeoff with my 160hp, fixed-pitch prop RV-6 is:

Smoothly apply throttle, 1, 2, 3, stick to approximately neutral, 4, 5, the plane flies off the runway with a slightly tail-low attitude. Be prepared to apply MUCH more right rudder than you did in the J-3.

The position of the stick will vary some depending on how the plane is loaded.
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  #5  
Old 10-31-2017, 02:21 PM
fbrewer fbrewer is offline
 
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Gentlemen,

Thanks for the input.

I like the mechanical: Smoothly apply throttle, 1, 2, 3, stick to approximately neutral, 4, 5, the plane flies off the runway with a slightly tail-low attitude.

I have my 2nd transition flight tomorrow.
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  #6  
Old 10-31-2017, 03:29 PM
luddite42 luddite42 is offline
 
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I'd suggest feeling what the airplane wants to do rather than being "mechanical" with the inputs. You will get a feel for when the tail will naturally come up with just a touch of forward stick. There's no good reason to force it up early with excessive forward stick. Let the tail come up to an attitude that puts the tailwheel 6-8" off the runway, hold that attitude, and let it fly off when ready...requires slightly increasing aft pressure as the airplane accelerates. The "mechanical" approach would be to force the tail to a level attitude, watch the airspeed, and then pull the airplane off the ground when you see an ASI number you like. That's not a very "artful" way to fly. I'd suggest keeping your eyes outside and feel and fly the airplane. No need to look at the panel during the T/O roll in a tailwheel airplane. There's also no such thing as the "right" way to do it.
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  #7  
Old 10-31-2017, 04:09 PM
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JonJay JonJay is online now
 
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It's a feel thing.

By the way, the Cub can take off three point, tail low, or planted as you where taught. Same for the RV. Experiment with each as you explore your airplane.
Trim position, weight, temperature, winds, all play a role.

By the way, when doing a section take off in formation, the tail is lifted when your lead does. They may be flying a different RV with different characteristics.

The nice thing about RV's is you can get away with murder compared to many tail wheel airplanes and still execute a safe take off.
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Last edited by JonJay : 10-31-2017 at 04:12 PM.
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  #8  
Old 10-31-2017, 04:34 PM
Scott Hersha Scott Hersha is offline
 
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Frank,
To answer your original question:

ďMy question in the RV-6 is this: if I go full forward on the stick in the RV-6 and hold, will the tail continue to rise as speed builds and eventually cause a prop strike?Ē

Yes, possibly... depends on gross weight, CG, headwind component, prop diameter, and a few air density variables. As speed builds, the download on the tail does too, so it eventually becomes less likely to get a prop strike in any tailwheel airplane. But in any RV taildragger, that is inherently less dynamically stable in pitch and therefore has less designed download on its tail than most certified airplanes, it would be more likely to get a prop strike in certain situations. If you applied a larger than necessary amount of nose down pitch on takeoff, and then had to abort your takeoff (even if you didnít drag your prop first) you may have a problem. Using any amount of initial braking in this situation invites a prop strike and possibly nose over, unless youíre really clever with your stick. Pulling back on the stick in this scenario would be a good idea, but too much, and your airborne - not what youíre looking for in a takeoff abort.

I donít have very much time in a Cub, but I do in a DC-3, which really just a large Cub, it is impossible to experience a prop strike aerodynamically with your elevator under normal circumstances, and itís that way with many certified tailwheel airplanes. That big horizontal tail sticking up in the breeze is your friend in this situation - not so much in an RV with its relative pitch authority v.s. HS area. We always did wheel landings in the -3 because to 3-point it, you had to be close to stall, which put you 20 knots below VMC. On touch down on a windy day I would usually apply full forward elevator. Even with braking, it would be unusual to have a problem. On takeoff - always used full forward elevator, just like the Cub. As others have said, a good technique in an RV is to let the tail float up, maybe with a little forward elevator (or not), and let it fly off in that tail low attitude. Adjusting pitch to maintain Vx/Vy wonít take much effort after that.
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  #9  
Old 10-31-2017, 05:15 PM
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JonJay JonJay is online now
 
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Sorry, I guess we got a little side tracked....

Wheel landings are done with stick full, or nearly full, forward. In that attitude, with a 72" prop, I have not heard of any prop strike issues, and I have made, and seen, some pretty awful wheel landing attempts !
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  #10  
Old 10-31-2017, 05:30 PM
luddite42 luddite42 is offline
 
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Quote:
Originally Posted by JonJay View Post
Wheel landings are done with stick full, or nearly full, forward.
I've never made that standard practice and don't advocate it, but I guess we can beat that issue up in the OPs next thread.
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