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  #1  
Old 05-19-2018, 09:39 AM
precession precession is offline
 
Join Date: Apr 2006
Posts: 137
Default "Slow Rolls," a/k/a Competition Aerobatic Rolls, in the RV

Having a problem doing “slow rolls” (old terminology, now I believe simply called “competition aileron rolls” by IAC) in the RV. Nose always dropping too much, so thought I’d put this question out there for the RV aerobatics guys.

Yes, I know that when inverted you must push forward on the stick to keep the nose from dropping. So the obvious answer might just be “push forward more when inverted to keep the nose up.”

However, my impression is that the nose has already dropped too much by the time I’m even getting to inverted. And I am suspecting the reason for that is either (a) that I should have pitched up at the beginning of the roll, or (b) that the rudder size on RV’s (in my case, the RV-4) is not enough by itself to keep the nose up when in knife-edge flight. That’s where we get to my question. Is it just that my technique sucks, or is it accurate that RV’s, which have relatively small rudders compared to competition aircraft, require some adjustment in technique when doing a slow roll?

I’ve read multiple descriptions of how to do the “slow roll,” and most seem to indicate you are not to start by lifting the nose; if you make a visible nose lift, it will be a downgrade. You are usually told that what keeps the nose up in the first quarter of the roll is “top rudder.” Well, it seems to me that if I apply no up elevator whatsoever when starting the roll, and try to rely solely on top rudder in the first quarter of the roll, the rudder alone does not have enough authority to keep the nose up.

So I am suspecting that what pilots are actually doing is applying some up elevator at the beginning of the roll to pitch up somewhat, BUT HOPEFULLY NOT ENOUGH TO CAUSE A NOSE RISE THAT IS PERCEPTIBLE TO THE JUDGES.

For example, I have watched multiple videos, including this one by the excellent RV and Pitts aerobatics pilot Hans Meisler (greetings Hans!) https://www.youtube.com/watch?v=GojqK3H8AiQ (at 4:55), and it certainly looks like a small amount of up elevator is being applied at the commencement of what I believe is a slow roll.

Here's another video of well-known aerobatics instructor John Morrissey teaching slow rolls in a Pitts, and he also starts with a little up elevator (and he even says out loud that is what he is doing): https://www.youtube.com/watch?v=7ncPJM-emCw (at 11:10).

So what’s the deal? Is that what needs to be done? You pitch up somewhat before starting the "slow roll," a/k/a competition "aileron roll"?
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Last edited by precession : 05-19-2018 at 09:44 AM.
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  #2  
Old 05-19-2018, 11:33 AM
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Saville Saville is offline
 
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Quote:
Originally Posted by precession View Post
Having a problem doing “slow rolls” (old terminology, now I believe simply called “competition aileron rolls” by IAC) in the RV. Nose always dropping too much, so thought I’d put this question out there for the RV aerobatics guys.

Yes, I know that when inverted you must push forward on the stick to keep the nose from dropping. So the obvious answer might just be “push forward more when inverted to keep the nose up.”

However, my impression is that the nose has already dropped too much by the time I’m even getting to inverted. And I am suspecting the reason for that is either (a) that I should have pitched up at the beginning of the roll, or (b) that the rudder size on RV’s (in my case, the RV-4) is not enough by itself to keep the nose up when in knife-edge flight. That’s where we get to my question. Is it just that my technique sucks, or is it accurate that RV’s, which have relatively small rudders compared to competition aircraft, require some adjustment in technique when doing a slow roll?

I’ve read multiple descriptions of how to do the “slow roll,” and most seem to indicate you are not to start by lifting the nose; if you make a visible nose lift, it will be a downgrade. You are usually told that what keeps the nose up in the first quarter of the roll is “top rudder.” Well, it seems to me that if I apply no up elevator whatsoever when starting the roll, and try to rely solely on top rudder in the first quarter of the roll, the rudder alone does not have enough authority to keep the nose up.

So I am suspecting that what pilots are actually doing is applying some up elevator at the beginning of the roll to pitch up somewhat, BUT HOPEFULLY NOT ENOUGH TO CAUSE A NOSE RISE THAT IS PERCEPTIBLE TO THE JUDGES.

For example, I have watched multiple videos, including this one by the excellent RV and Pitts aerobatics pilot Hans Meisler (greetings Hans!) https://www.youtube.com/watch?v=GojqK3H8AiQ (at 4:55), and it certainly looks like a small amount of up elevator is being applied at the commencement of what I believe is a slow roll.

Here's another video of well-known aerobatics instructor John Morrissey teaching slow rolls in a Pitts, and he also starts with a little up elevator (and he even says out loud that is what he is doing): https://www.youtube.com/watch?v=7ncPJM-emCw (at 11:10).

So what’s the deal? Is that what needs to be done? You pitch up somewhat before starting the "slow roll," a/k/a competition "aileron roll"?
I don't have the answer to your question - I am working out the same thing and having the same issues though I tend to dish out at the 180 to 270 degrees of roll mark.

But one technique an aerobatic instructor gave me was to just do the first 45 degrees of roll and get that down. Hold it in the 45 using rudder to adjust for altitude. Repeat it until you can put the nose exactly where it needs to be at the 45 degree mark, smoothly without having to think about how much rudder to put in. Then go to 90 and do those over and over until you are set up nicely.

I found this advice to be useful.
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Last edited by Saville : 05-19-2018 at 02:53 PM.
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Old 05-19-2018, 02:40 PM
sandifer sandifer is offline
 
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How are you sure the nose is dropping too much inverted? Are you below the pitch attitude required for inverted level flight for your specific airspeed? That pitch attitude should be burned into your brain for the speed you're flying. Have you had any qualified ground critiquing to support your concerns? First of all, ignore that John Morrissey video. Not because he's unqualified or doesn't know how to do a good level roll, just the opposite. He's giving primary acro instruction to a rank newbie. The pitch up during the "slow roll" section is simply to set the student up for the ability to work on the inputs required (knowing the inputs will be imperfect) without blowing out too low and fast, requiring instructor intervention. This is certainly not how you do a quality competition roll in a Pitts. The Pitts needs zero pitch up.

I wouldn't get too analytical about it until you have the chance to get some good ground critiquing/coaching. But....some airplanes with a slow roll rate can benefit from a very subtle and minute pitch up simultaneous with (but not before) the aileron input. Citabrias and Decathlons apply. IMO, RVs roll fast enough that this technique has questionable value. But you must be very smooth and subtle about it, and only apply it during the first 10-15 degrees or so of rotation, otherwise you will barrel off heading. Any pitch up at all seen prior to starting the roll with subtract one point per 5 degrees from your score. There is no one exact right technique. Whatever looks good from the ground, and if you are cheating slightly, whatever you can get away with. If you haven't picked up on it by now, be aware that you should do the roll as quickly as possible. "Slow roll" is a misnomer - they should be done with full aileron deflection as fast as possible. The quicker you can get through the roll, the less time there is for deviations to occur and for them to be seen.

Again, RVs don't have much side fuselage area for good knife edge performance, but again, RVs roll fast enough to transition through it without much trouble. A fun exercise in something like the Pitts (good knife edge performance) is the 'super slow roll'. The objective is to roll as slow as possible while maintaining a constant roll rate, heading, and altitude. Not sure how well the RV will do with this, but it's something fun to try to gauge knife edge performance and for the hand-eye challenge. Shot an attempt a couple years ago in my old Pitts. But I'm convinced there is pitot-static altimeter error at each knife edge position. Not perfect, but not easy. No initial pitch up required.

http://www.youtube.com/watch?v=UdMWcQYZXsU
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  #4  
Old 05-19-2018, 03:58 PM
jrs14855 jrs14855 is offline
 
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Sandifer is correct about speed helping the roll. I hammered the airlerons in the Pitts S1S for years at speeds up to Vne. I question the wisdom of doing this in the RV. This is based on a discussion with Van many years ago. In respect to the airplane I think the best compromise is a fairly high speed with a bit less than full aileron.
I would recommend the Bill Thomas book as a starting point for the controls required.
In the Pitts at or near Vne you can simply put the ailerons to the stop and get a good score. For an immelman, especially at lower than planned speed, a lot more finesse is required.
Another alternative is to look at this in terms of control "settings" Looking just at the elevator, at 140 ias you will have a greater up elevator setting than at 150 ias. The elevator and also the rudder inputs must be constantly adjusted thruout the roll. For example carrying a touch of up elevator to far into a roll will cause the elevator to yaw the airplane slightly off heading. Too much or too little rudder will result in similar errors.
A simple mental excersize to help understand: with a model airplane simulate sustained knife edge. In a sustaained 90 degree bank the rudder becomes the elevator and the elevator becomes the rudder. The Pitts S1S from Vne will fly half a mile in knife edge and the climb 3-500 feet, finishing at 90 ias. Most of the high performance monoplanes perform very poorly by comparison.
Using the model airplane think your way through the roll in 90 degree segments. Analize rudder and elevator errors and what the results will be.
The model airplane is a very important part of the pre and post flight ground training that should be a part of a proper aerobatic lesson.
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Old 05-19-2018, 04:30 PM
precession precession is offline
 
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Quote:
Originally Posted by sandifer View Post
How are you sure the nose is dropping too much inverted? Are you below the pitch attitude required for inverted level flight for your specific airspeed? That pitch attitude should be burned into your brain for the speed you're flying. Have you had any qualified ground critiquing to support your concerns?
Thanks for the reply. I'm aware of instructions that say you should start by flying inverted at different air speeds to determine what amount of forward stick is required at a given air speed to keep the nose up (maintain level flight) while inverted. Unfortunately, I haven't been able to do that because of the lack of inverted systems.

As to ground critiquing, no, I have not yet gotten any to confirm or disprove. So my feeling is mainly based on the strong sense that the nose is dropping immediately as I'm getting into the first knife edge (and top rudder is not enough to hold it up), and the fact that I'm ultimately coming out of the roll at a little lower altitude and having to pull up a little to get back to level flight.

Also, although I haven't made any extended attempts to see how the RV flies in knife edge (because of the lack of inverted systems), I've tried it briefly and it seems like it really doesn't have the ability to keep the nose up. The guys w/ inverted systems might be in a lot better position to report on this though.

I'm definitely open to the idea that I just haven't been putting in enough forward stick while inverted, but I thought I'd ask.

Quote:
If you haven't picked up on it by now, be aware that you should do the roll as quickly as possible. "Slow roll" is a misnomer - they should be done with full aileron deflection as fast as possible. The quicker you can get through the roll, the less time there is for deviations to occur and for them to be seen.
No, I actually haven't been trying to do it as fast as possible - so valuable info. I definitely haven't been going slow, but have been trying to go at a rate that allows me to try to feed in the correct movements.
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  #6  
Old 05-19-2018, 04:43 PM
precession precession is offline
 
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Quote:
Originally Posted by jrs14855 View Post
Sandifer is correct about speed helping the roll. I hammered the airlerons in the Pitts S1S for years at speeds up to Vne. I question the wisdom of doing this in the RV. This is based on a discussion with Van many years ago. In respect to the airplane I think the best compromise is a fairly high speed with a bit less than full aileron.
I would recommend the Bill Thomas book as a starting point for the controls required.
In the Pitts at or near Vne you can simply put the ailerons to the stop and get a good score. For an immelman, especially at lower than planned speed, a lot more finesse is required.
Another alternative is to look at this in terms of control "settings" Looking just at the elevator, at 140 ias you will have a greater up elevator setting than at 150 ias. The elevator and also the rudder inputs must be constantly adjusted thruout the roll. For example carrying a touch of up elevator to far into a roll will cause the elevator to yaw the airplane slightly off heading. Too much or too little rudder will result in similar errors.
A simple mental excersize to help understand: with a model airplane simulate sustained knife edge. In a sustaained 90 degree bank the rudder becomes the elevator and the elevator becomes the rudder. The Pitts S1S from Vne will fly half a mile in knife edge and the climb 3-500 feet, finishing at 90 ias. Most of the high performance monoplanes perform very poorly by comparison.
Using the model airplane think your way through the roll in 90 degree segments. Analize rudder and elevator errors and what the results will be.
The model airplane is a very important part of the pre and post flight ground training that should be a part of a proper aerobatic lesson.
Thanks also for the reply - also valuable information.

Although I don't think I've been rolling slow, I have to say I have not been throwing in full aileron hard to the stop, just because I've been concerned over possibly abusing the airplane and thinking maybe I should be able to do it well without going really that forcefully to the stop. Have to admit I also am not exactly stomping on the rudder pedals when going in knife edge either, basically for the same reasons. I'm concerned that the RV, even if capable of a lot, is not exactly designed for more full force type control applications that I gather might be more typically done in something like a Pitts.
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Last edited by precession : 05-19-2018 at 08:15 PM.
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  #7  
Old 05-19-2018, 05:21 PM
spatsch spatsch is offline
 
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Speed clearly helps your roll. 150mph is plenty, faster doesn't hurt.

The current sportsman routine has a roll after an immelman turn. The max speed I can get to before flying out of the box in that sequence is around 110mph. RV still rolls fine based on ground observer. I am just not consistent at that speed ... but that's all me.

I do use full aileron and rudder. The RV has no problem with that. That might be your problem. If you stay in knives edge for any extended period of time you need a lot of speed in an RV. So you either need to roll with full aileron or enter much faster then 150.

I also noticed in your signature that you are in NJ. Just FYI IAC chapter 58 has a monthly practice day with ground observers available. IAC and chapter membership is required but otherwise it's free. If you are interested send me an email (oliver@spatscheck.com).

Oliver
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Old 05-19-2018, 08:06 PM
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RV8Squaz RV8Squaz is offline
 
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What Eric Sandifer said was perfect.

I will just add that at I high speeds (160 knts +) at the bottom of figure simply full or near full aileron with a slight nudge forward on the stick going through inverted is enough to do a nice roll. A little extra technique with the rudder will keep you from losing a point for barreling the roll.

At low speeds, such as the top of an immelman, I do find it necessary to blend in back stick at the initiation of the roll, top rudder, forward stick, top rudder, and back stick. I definitely use full aileron in this case. It's not a thing of beauty, but it works for me.
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Old 05-19-2018, 08:33 PM
1flyingyogi 1flyingyogi is offline
 
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What you said about lack of inverted systems was EXACTLY my problem also. Of course a lot of practice and ground critiquing/ tips from guys who are more experience certainly helped. But I would say 90% of it was just lack of inverted fuel - at least for me. Before fuel injection, I simply could not push enough forward elevator to maintain altitude through inverted b/c the engine would quit or at least hesitate. (Most of the time it just quit). So my technique was to use a huge a mount of rudder to compensate for the altitude loss through inverted and it was just a big mess.

As soon as I installed my fuel injection, it was night and day difference. I know many guys say you don't need inverted systems and can fly up to the sportsman level, but my experience does not agree with that. I guess you *can* do it, but it will be ugly and you would have to fudge so many of the figures just to prevent the engine from quitting that it's simply no fun.

I had the exact same complaints as you and posted a similar thread on the Yahoogroups forum. Within a week of installing my inverted fuel, I had no more problems rolling, and the guy who did my ground critiquing said my rolls are my best maneuvers. (I'm certainly not saying I'm an expert at it, but good enough to not consider it a "problem" anymore)

This is all a long-winded way of saying, get inverted fuel (and oil)! Even if you don't compete, it's so much more fun to fly aerobatics! Without inverted fuel, I could not even do vertical up-lines without the engine quitting. Which means no hammerheads, no humpty-bumps, etc. You cannot even do the half cuban 8 in the primary sequence without it quitting. It's extremely limiting to not have inverted fuel. At least that was my experience...









Quote:
Originally Posted by precession View Post
Thanks for the reply. I'm aware of instructions that say you should start by flying inverted at different air speeds to determine what amount of forward stick is required at a given air speed to keep the nose up (maintain level flight) while inverted. Unfortunately, I haven't been able to do that because of the lack of inverted systems.

As to ground critiquing, no, I have not yet gotten any to confirm or disprove. So my feeling is mainly based on the strong sense that the nose is dropping immediately as I'm getting into the first knife edge (and top rudder is not enough to hold it up), and the fact that I'm ultimately coming out of the roll at a little lower altitude and having to pull up a little to get back to level flight.

Also, although I haven't made any extended attempts to see how the RV flies in knife edge (because of the lack of inverted systems), I've tried it briefly and it seems like it really doesn't have the ability to keep the nose up. The guys w/ inverted systems might be in a lot better position to report on this though.

I'm definitely open to the idea that I just haven't been putting in enough forward stick while inverted, but I thought I'd ask.



No, I actually haven't been trying to do it as fast as possible - so valuable info. I definitely haven't been going slow, but have been trying to go at a rate that allows me to try to feed in the correct movements.
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Old 05-19-2018, 08:58 PM
spatsch spatsch is offline
 
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I think you are mixing two things up.

I agree that you want an engine with fuel injection to prevent your engine from quitting, however, you donít need an inverted system for sportsman.

I donít have one and my engine never even runs rough during the sportsman routine. I can fly >5sec inverted before my oil pressure hits Lycoming minimum and I never managed to starve the engine of fuel during that time. Thatís more then enough time for sportsman.

Oliver


Quote:
Originally Posted by 1flyingyogi View Post
What you said about lack of inverted systems was EXACTLY my problem also. Of course a lot of practice and ground critiquing/ tips from guys who are more experience certainly helped. But I would say 90% of it was just lack of inverted fuel - at least for me. Before fuel injection, I simply could not push enough forward elevator to maintain altitude through inverted b/c the engine would quit or at least hesitate. (Most of the time it just quit). So my technique was to use a huge a mount of rudder to compensate for the altitude loss through inverted and it was just a big mess.

As soon as I installed my fuel injection, it was night and day difference. I know many guys say you don't need inverted systems and can fly up to the sportsman level, but my experience does not agree with that. I guess you *can* do it, but it will be ugly and you would have to fudge so many of the figures just to prevent the engine from quitting that it's simply no fun.

I had the exact same complaints as you and posted a similar thread on the Yahoogroups forum. Within a week of installing my inverted fuel, I had no more problems rolling, and the guy who did my ground critiquing said my rolls are my best maneuvers. (I'm certainly not saying I'm an expert at it, but good enough to not consider it a "problem" anymore)

This is all a long-winded way of saying, get inverted fuel (and oil)! Even if you don't compete, it's so much more fun to fly aerobatics! Without inverted fuel, I could not even do vertical up-lines without the engine quitting. Which means no hammerheads, no humpty-bumps, etc. You cannot even do the half cuban 8 in the primary sequence without it quitting. It's extremely limiting to not have inverted fuel. At least that was my experience...
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