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

[WillyEyeBall]

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

[mike newall]

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/pooleys...on-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

[ronschreck]

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.

[jrs14855]

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.

[mike newall]

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.

[1flyingyogi]

Originally Posted by spatsch

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.

[SHIPCHIEF]

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!

[ronschreck]

Originally Posted by SHIPCHIEF

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.

[sandifer]

Originally Posted by 1flyingyogi

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.

[precession]

Originally Posted by 1flyingyogi

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.