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"Slow Rolls," a/k/a Competition Aerobatic Rolls, in the RV

precession

Well Known Member
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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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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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
 
Rolls

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.
 
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.

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.
 
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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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 ([email protected]).

Oliver
 
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.
 
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...









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.
 
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 don?t need an inverted system for sportsman.

I don?t 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. That?s more then enough time for sportsman.

Oliver


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...
 
An RV is not a Pitts

I have inverted fuel and oil systems, so it?s much easier to learn how to do a competition slow/aileron roll where altitude and heading stay the same for the complete roll. From the pilot?s view, it looks like the nose is pointed in one direction/heading, but changes vertical pitch angle relative to the horizon at different parts of the roll. If you look at this youtube video of the Primary sequence in an RV-4 with the last maneuver at 1? 52?, which is a roll, you?ll see the different nose pitch angles.
https://www.youtube.com/watch?v=PhJHdb9k7Ho
In the video clip, you can pause it at the four roll positions (0, 90, 180, 270, 0) to see the nose angles relative to the horizon.
Straight and level upright, the nose is below the horizon. Going through knife edge at first and 3rd quarters, the nose is on the horizon. Inverted, the nose is well above the horizon, which would be the sight picture for sustained inverted level flight at that airspeed. Unlike other aerobatic aircraft such as a Pitts, the RV has differential ailerons. This means when you roll, you?re not getting much adverse yaw (opposite rudder effect), which is necessary to minimize and reduce the nose pitch down tendency in the first quarter of the roll. When I start a roll, I simultaneously apply substantial opposite rudder, and hold it in just pass the knife edge point, where I start pushing the stick firmly till just before the second knife edge. From the inverted position in the roll, I switch to the other rudder (top rudder). The elevator pressure changes continually throughout the roll to keep the nose pointed in the right direction and sustain level flight without gaining or losing altitude. With inverted systems, we learned the necessary stick and rudder inputs by doing two-point rolls, with a 3 or 4 second pause when inverted before completing the roll. Practice, practice, practice, practice, and eventually you can score well.
Hope this helps.
Bill McLean
RV-4 slider
Lower AL
 
It would probably help to do a little study.

One of the easiest to read and understand books is Flight Unlimited '95 by Eric Mueller and Annette Carson.

https://www.pooleys.com/shop/pooley...light-unlimited-95-annette-carson-eric-muller

The diagrams and narrative are simply written and illustrated and one of the first things he talks about is horizon awareness and in rolling, the Sacred Circle. It is the circle traced by the nose as you progress around the roll as your feet are dancing merrily on the rudder to 'climb the nose' in the first 90, then accept the weight in the inverted and hold the nose on the 3rd segment.

It is a busy time and one thing he says is to practise slower and slower as coordination exercises. It really gets you thinking !

You can then extend to slower and slower rolls, both in rate of roll and airspeed.

Be prepared for lots of rudder as it slows down :D
 
RV aerobatics are alive and well.

I'll not add anything to the discussion of competition aileron roll techniques but I will say that I am impressed with the quality and quantity of the above posts in response to the initial query. There is a lot of aerobatic expertise to be had on this forum which is unique to the RV aircraft. Dick VanG did not set out to design an aerobatic airplane, rather he designed a series of aircraft that don't do anything perfectly but do just about everything with a skilled pilot doing his best to overcome the deficiencies inherent in an airplane that fills a variety of rolls. To me, the challenge to perform competition aerobatics in an airplane that was not designed for the task is most gratifying and on the occasions where I fare better than the opposition who is flying an Extra or Pitts the sense of accomplishment is well worth the effort it takes to excel. A few years ago I flew my RV-8 to Sebring, FL for the Fall competition. The weather en-route from my home in North Carolina was IMC for much of the way so I filed and made the trip in just under four hours. Only a few of the competitors who lived nearby Sebring were on the ramp when I arrived and they gathered to watch as I stepped off the wing. From the back seat my wife handed me Riley, our pet chihuahua and I put him on his leash. Then she handed me Sophie, our other chihuahua. I helped Kathy from the plane and then we unloaded two bags and the dog kennel from the rear baggage compartment and another bag or two and the tool kit from the front baggage compartment. That weekend I managed a third place finish in a Sportsman field of fourteen. The final day of competition went long so I flew home and landed in the dark while most stayed another night so they could arrive home in daylight hours. The versatility of my RV was showcased that weekend in Sebring and the sense of pride and accomplishment that this airplane brings to me has been the spark that keeps me going at an age where most are content with comfortable sofa, a cold beer and a big screen TV.

I am often asked, "why I don't you buy a Pitts or an Extra? They are made for aerobatics!" Read the above paragraph. ;)
 
Extras.etc

Imagine the disappointment of dropping 4-500k for an Extra or whatever and finding after you bought it that it doesn't knife edge any better than an RV, is less comfortable for cross country and there is not enough room for the dogs etc etc.
 
Great post Ron.

We took our 7 down south yesterday (180 miles).

Grass strip, Aeroncas, Rans, Beagles, Stampe etc. Bit of a cook out, some lemon cake and fine English tea !

It avoided some wedding that was going on.

Anyhow - I took 3 folks flying, turned them upside down ever so gently in the 7, one of them for the first time and had all three chuckling afterwards.

Nothing above 3g.

What a machine - you can blow their socks off with the departure (180hp, MT 3 blade), amaze them with the visibility and light handling, demonstrate sublime aeros - empty pattern, whiz downwind at 170kts, round the corner for a landing, tea and medals.

No, I wouldn't do competition aeros in mine, not what it was designed for, but as you say, a superb good all rounder.

Mr Rourke would be proud of me.... sadly missed friend from some time ago.
 
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 don?t need an inverted system for sportsman.

I don?t 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. That?s more then enough time for sportsman.

Oliver

Consider yourself lucky Oliver. Maybe my engine for some reason was particularly sensitive to zero or negative G's (more so than it's supposed to be)?? My engine has quit more times than I'd like to remember, many times with the prop NOT windmilling and required me to crank the engine to get it started again. Even momentary zero/ negative G and it'll quit. If the OP's engine isn't so sensitive, then maybe he doesn't need to get inverted fuel. For me, fuel injection was by far the best single mod I made for aerobatics.
 
I tried the Power Sportsman 2018 Known yesterday in my RV-8. It's O-360, Catto 3 blade and has Airflow Performance fuel injection. It does not have inverted fuel or oil.
It never missed a beat and the oil pressure stayed up.
That said, I have the same problem with the roll. I appreciate the help here.
My Yak-55 is out of service, I cooked the two LiFePO4 batteries; I charged them too fast when they were nearly dead. (my bad) Also my butt pack chute isn't back from re-pack.
I am totally aware of the cross country advantage of an RV compared to a Yak.
I'm needing Marilyn (my wife) to fly her RV-4 with tools, a small SCUBA bottle, and plenty of oil & rags + our packs with me to each contest.
I have to keep asking her to slow down too!
 
I tried the Power Sportsman 2018 Known yesterday in my RV-8. It's O-360, Catto 3 blade and has Airflow Performance fuel injection. It does not have inverted fuel or oil.
It never missed a beat and the oil pressure stayed up.
That said, I have the same problem with the roll. I appreciate the help here.
My Yak-55 is out of service, I cooked the two LiFePO4 batteries; I charged them too fast when they were nearly dead. (my bad) Also my butt pack chute isn't back from re-pack.
I am totally aware of the cross country advantage of an RV compared to a Yak.
I'm needing Marilyn (my wife) to fly her RV-4 with tools, a small SCUBA bottle, and plenty of oil & rags + our packs with me to each contest.
I have to keep asking her to slow down too!

I was wondering, whatever happened to you? You flew your RV-8 in a couple of contests a few years ago and last year: nothing. You have been competing in the Yak! I flew a 55M once and was amazed at the truly unconventional cockpit and the very limited speed range within which it does some amazing aerobatics. Fun airplane! I wish you great success in whatever airplane you select for competition. (We should all have at least three to choose from!) Do a few in the -8 and secure your place among the others in the RV IAC Competition Standings. Good luck.
 
Consider yourself lucky Oliver. Maybe my engine for some reason was particularly sensitive to zero or negative G's (more so than it's supposed to be)?? My engine has quit more times than I'd like to remember, many times with the prop NOT windmilling and required me to crank the engine to get it started again. Even momentary zero/ negative G and it'll quit. If the OP's engine isn't so sensitive, then maybe he doesn't need to get inverted fuel. For me, fuel injection was by far the best single mod I made for aerobatics.

Brian, I think you're confusing what Oliver was saying. Oliver has fuel injection. There are no figures in Sportsman with long enough negative G duration to require a flop tube (inverted fuel). That's why he said he doesn't need inverted systems in Sportsman if you have FI. You might just want an oil separator/slobber pot though.

Nobody is saying they are running a standard float carb and not having engine power issues at zero or negative G. Any float style carb will cause your engine to quit as soon as you go negative. But this is really not a problem either as long as the prop keeps windmilling. Metal props help here. I have a friend with a 100HP carb'd, non-inverted Clipped Taylorcraft w/ metal prop who did well in Sportsman and didn't modify the figures any. Metal props will windmill forever unless you get extremely slow for too long - which is unlikely. Wood props will easily windmill through a roll, but do something like a reverse wedge with a wood prop, and it'll likely go dead stick.
 
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Fuel Injection is "inverted fuel" (minus the inverted tank tho)

Consider yourself lucky Oliver. Maybe my engine for some reason was particularly sensitive to zero or negative G's (more so than it's supposed to be)?? My engine has quit more times than I'd like to remember, many times with the prop NOT windmilling and required me to crank the engine to get it started again. Even momentary zero/ negative G and it'll quit. If the OP's engine isn't so sensitive, then maybe he doesn't need to get inverted fuel. For me, fuel injection was by far the best single mod I made for aerobatics.

My carburetor-equipped engine also stops quickly in zero or negative G. I have a Catto prop (not metal), and it does not keep windmilling beyond anything other than a very brief power interruption while at speed. I also have had it stop and had to crank the starter to get the engine going (after wasting a bunch of altitude finding out that diving wasn't getting the prop to move). I'm not comfortable with that as a normal (or even irregular) practice, and I especially don't think it's a great idea at the lower altitudes you'd fly in a contest (I've mostly been practicing around 5K.) So I agree with you even about the negative 45 degree down of the 1/2 cuban called for in most primary sequences. I guess if I enter a contest, I'll just do a roll there and take the deduction rather than risk drawing the straight inverted line and having the engine/prop possibly stop at that altitude.

As for in-line aileron rolls though, I often get an engine stumble but usually the prop keeps spinning.

I don't think spatsch knows me by name (think I'll shoot him an email), but I've had the pleasure of meeting him and admiring his airplane, and if I recall correctly (and sandifer now confirms), he has fuel injection. Although I'm the guy asking questions here (and learning a lot from the fantastic replies), I think I can still say, at least in my opinion, that if you have fuel injection, you have the most important part of an "inverted fuel system."

I think there's a thread where Ronschreck says he flew his fuel injected RV-8 (without inverted fuel tank w/ flop tube) the length of an airfield inverted without it stumbling. And Spatsch says he can fly a good while while inverted based just on his fuel injection, without the inverted fuel tank or oil system. Which I think shows that of the two parts of an "inverted fuel system" -- (1) being fuel injection/throttle body/pressure carb, and (2) being inverted tank/flop tube -- the fuel injection is far more important, and you can do a lot with just that.

Sandifer and others I've heard have said if you have a metal prop the prop will keep windmilling during the brief engine stoppages, so it's apparently no problem. But if you have a wood/composite prop I think you're in a somewhat different situation, especially for example at the top of a hammerhead, where my engine & prop have stopped cold. So I see your point that having inverted fuel (even w/o the tank/flop tube) would be great. Hopefully I'll get up to speed there, but right now I'm repairing a fuel tank. :)
 
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My carburetor-equipped engine also stops quickly in zero or negative G. I have a Catto prop (not metal), and it does not keep windmilling beyond anything other than a very brief power interruption while at speed. I also have had it stop and had to crank the starter to get the engine going (after wasting a bunch of altitude learning that diving wasn't doing the trick). I'm not comfortable with that as a normal (or even irregular) practice, and I especially don't think it's a great idea at the lower altitudes you'd fly if in a contest (I've been practicing around 5K.) So I agree with you even about the negative 45 degree down of the 1/2 cuban called for in most primary sequences. I guess if I enter a contest, I'll just do a non-negative roll there and take the deduction rather than risk drawing the straight inverted line and having the engine/prop stop.

I don't think spatsch knows me by name (I'll probably shoot him an email), but I've had the pleasure of meeting him and admiring his airplane, and if I recall correctly (and sandifer now confirms), he has fuel injection. Although I'm the guy asking questions here (and learning a lot from the fantastic replies), I think I can still say, at least in my opinion, that if you have fuel injection, you have the most important part of an "inverted fuel" system.

I think there's a thread somewhere where Ronschreck says he flew his fuel injected RV-8 (without inverted fuel tank w/ flop tube) the length of an airfield inverted without it stumbling. And Spatsch says he can fly a good while while inverted based just on his fuel injection, without the inverted tank or oil system. Which I think shows that of the two parts of an "inverted fuel system" -- (1) being fuel injection/throttle body/pressure carb, and (2) being inverted tank -- the fuel injection is far more important, and you can do a lot with just that.

Based on what Sandifer, and others I've heard, have said, if you have a metal prop the prop will keep windmilling during the brief engine stoppages, so it's apparently no problem. But if you have a wood/composite prop you're in a different situation, especially for example at the top of a hammerhead, where my engine & prop have stopped cold.

You are correct on all points. I produced an EAA Webinar on the subject of equipping your RV for aerobatics and even listed my priorities for doing so. Fuel injection is near the top of the list and inverted fuel is near the bottom. I know that money is often a deciding factor when equipping your airplane for any endeavor so putting money where it will do the most good is important.
 
Sorry if I confused people with my reply.

I don't consider fuel injection part of an inverted system.... . So for me inverted system means inverted fuel pickup and oil. Hope that explains it.

And yes precession I don't know you by name.

Oliver
 
Thanks

Sent you an email, Spatsch.

Looks like this thread may have just about run it's course, so just wanted to say many thanks to everyone who replied. Read every post carefully, went to every link, watched every video linked (some excellent videos by the way), and received lots of valuable information and advice.

Happy flying to all.
 
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Sorry if I confused people with my reply.

I don't consider fuel injection part of an inverted system.... . So for me inverted system means inverted fuel pickup and oil. Hope that explains it.

And yes precession I don't know you by name.

Oliver

I see what you mean. In that case, I don't have inverted systems either. Just fuel injection, no flop tube and only a "half" Raven system which is nothing more than a glorified air/ oil separator. :)

That was a very cool super slow roll, Eric! Maybe a fastback -4 with the bigger fuse side area can do it - barely?? :D
 
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