entry speeds / how to do.... basic aerobatics Waiex?

[gyroron]

Trying to understand what maneuvers I can do, and how to do them in my Waiex.

I have done many barrel rolls... Typically starting at around 120-130 mph, bring the nose up 30 - 40 degrees, then full stick either left or right, comes around fairly quick and ends close to level attitude with minimal altitude or speed loss.

I have done a few Split S's... Typically, starting around 100 mph, simply chopping power to idle, nose level, roll to the right or left to inverted and pull a little back pressure on the stick to come around. Probably not pulling enough on the downline as I am seeing lots of altitude loss and speeds approaching 175 mph.

Yesterday I was going to attempt my first loop... Had no idea what speed to enter it at. Was at full throttle in a slight dive, at around 150 mph I started to pull back, Did not look out at wingtip like I should have... Got plane pointed likely to about vertical and chickened out, reduced power and stomped hard right rudder and did a hammerhead / wingover type of maneuver...

Not sure why I am scared to loop the plane. I had a Vans RV-4 and would loop and roll it often. Had a titan Tornado and would loop and roll it quite a bit. And have owned several Phantom ultralights and loops and rolls were done on almost every flight in those.

[GraemeSmith]

In my 80hp AeroVee Sonex I shallow power dive to 125KIAS as the entry speed. Smooth 3-4G pull at full power, smoothly lessening the pull and G on the way up and about 1G over the top to keep the oil pressure on. Airspeed over the top is about 40KIAS - though there is probably some calibration error there. The plane is still flying well. Retard throttle as she comes over the top and pulling it smoothly and hard to 3-4G at the finish. Never so "light" over the top as to "float" or go negative G. Little left rudder on the way up and she is level when inverted. A little right rudder on the way down to come out level. I lean slightly before the pull into the loop as the Aerocarb seems to rich and stumble slightly on the initial pull.

If I get good smooth 4 G pulls at start and finish without an accelerated stall I don't lose altitude. If I only pull 3G at start and finish it costs about 300-500ft of altitude.

I find the loop the easiest of all the maneuvers to do and of course - hard to do WELL.

This sequence starts with a loop and finishes with some loops to form a cloverleaf - though my ear went haywire and I didn't complete the cloverleaf. Skip ahead to 1:28



YMMV!

[XenosN42]

Hi Ron,

Here's a video of a Sonex doing some aerobatics showing the airspeeds. Hope it helps!

https://www.youtube.com/watch?v=nWH4UZ6ntTo

[hickej]

Please everyone, get instruction before venturing into aerobatics. The barrel roll went very wrong for a friend of mine in a Waiex who did not neutralize the stick before applying full aileron. He ended up diving at the ground inverted because he was still applying up elevator. He pulled it out just in time.
Safe flying - it’s the only thing left to do!
-Jim

[sonex1374]

In my 80hp AeroVee Sonex I shallow power dive to 125KIAS as the entry speed. Smooth 3-4G pull at full power, smoothly lessening the pull and G on the way up and about 1G over the top to keep the oil pressure on.

Graeme is spot on here. To achieve a good loop you need to pull hard enough at the beginning. A 3-G pull is about the minimum needed to keep the speed from bleeding off too rapidly over the top, and a 4-G pull works even better. It may seem like pulling less G is easier on the airplane, but it's counter productive. The plane can handle it just fine, and the bigger danger is falling out of the loop over the top and barreling down toward the ground in the resultant recovery. That's a way to build a lot of speed, and a lot of G's, and that can definitely hurt the plane!

My recipe is simple: 130-140 mph entry speed, pull to 3-4 G's, release the back pressure to float over the top, and then bring the G's back in on the backside during the pull out. If you pull too hard on the backside you'll feel the elevator "shudder" a bit as the wing nibbles at a secondary stall.

A final thought about the inverted portions of our simple aerobatics. We all know that our planes don't have inverted fuel and oil, but so long as even a little positive G is on the airplane, things still work just fine. I do this all the time in rolls by pushing just a touch of down elevator while inverted (just enough to get to maybe 1/2 or 1/3 G, definitely not zero or negative G's). The engine never misses a beat, and the oil stays in the engine and not out the breather. I've even filmed these with my GoPro just sitting on the glareshield (not attached to anything) - it stays put just fine.

Jeff

[mike.smith]

Pretty much the same as Graeme and Jeff, except I think Jeff's Jabiru can do it from level flight. With a VW you have to start by going downhill to gain speed. In doing so you can over-rev the engine. I do everything in knots... 130-140 kts. Throttle back on the downhill to not over rev. Pull back on the stick (not abruptly, but firmly and with conviction). Increase to WOT on the way up. Feed in a little left (for a VW) rudder. Lighten the pressure on the stick before the apex, and let the plane go over the top and get its nose going down hill on it's own. Right as I start the back side of the loop I throttle back to keep from over-reving. Decrease the pressure on the rudder as you finish. How much depends on what you see as you look at the horizon. Pull the stick smoothly back until you're level again. I've never needed any right rudder, only left rudder.

If you don't lighten the back pressure at the top, not only will it be egg shaped, but you'll likely exceed the critical AOA and stall. I did that several times when I was first looping the Sonex (my training had been in a different aircraft type). The plane just mushed out and rolled upright on its own, more or less.

For a split S, or reverse half Cuban, I don't exceed 70 kts, so the throttle is always retarded when I start. I'll throttle back a little more on the down line if it looks like I'm carrying excess speed. Otherwise you can easily get past Vne in a hurry.

[Rynoth]

My loops have been 130KT decending entry full power (Aerovee Turbo climb prop), no issue with RPM keeping max cruise power setting (35" MAP). 2-3 g's on entry if my g-meter was correct.

I will say that my Lift Reserve Indicator (~AOA) was my primary instrument nearing the top of the loop, I was able to keep 1 eyeball on it and adjust back-pressure accordingly to stay just shy of the stall buffet. I LOVE that instrument.

https://www.youtube.com/watch?v=n6uxv3ie2dw

On my first loop I looked overhead for the horizon, which was a bit disorienting and obviously made my headset fall off. Subsequently I watched the wingtip and my LRI and it was much more comfortable.

Make sure you chop the power as the nose slices down through the horizon, as the g's set in very quickly once you're pulling back up and away from the earth and airspeed quickly builds.

[Sonerai13]

Please everyone, get instruction before venturing into aerobatics.....

I wholeheartedly agree with this. The Sonex line of aircraft are all very clean from a drag standpoint, and when you get them pointed at the ground the speed builds up FAST. This can be very dangerous because seeing the ground appearing to rush up at you at that rate generally causes and almighty pull on the stick and VERY rapid rise in G loads. The airplane will likely stall before it breaks, but that can lead to its own set of problems, especially as altitude rapidly diminishes. This is not for the faint of heart. Instruction is really the only safe way to do this.

And if I read y'alls descriptions right, what you are calling a "barrel roll" is actually and aileron roll (sometimes called a "ballistic roll"). A true barrel roll is performed more like a loop, with aileron added in. It is in effect an elongated loop and takes time and altitude to perform. It doesn't happen fast like an aileron roll.

The bottom line is that aerobatics are fraught with peril and should not be undertaken without proper training, especially in a "slippery" airplane that can get you in BIG trouble in a big hurry.

Be safe!

[mike.smith]

I did my aerobatic training in a Decathalon, which is a much draggier airplane. I had to learn the numbers that worked for my Sonex. So when people ask for things like entry speeds and techniques fore a Sonex, I'm happy to share my experiences. I just have to assume they've gotten proper training before doing aerobatics in their Sonex. Incidentally, I start all my aerobatics at 5,000' AGL, and 3,000' is my personal hard deck as I lose altitude doing multiple maneuvers.

I also have a laminated 6x5 piece of a sectional in the side pocket, with all the legal aerobatic areas delineated. I make sure I'm in those areas when doing aerobatics. Busy airspace near Boston. Having ADSB (in) is nice to get an initial read on the local traffic shortly after take-off, to decide which area I'm going to head for to practice in.

[Arjay]

All you acro guys are making me drool. I have not yet been able to do any acro in My Sonex. It has an 80 hp aerovee with aerocarb. A couple of years ago my mechanic was out for a test flight, pulled the airplane up into the start of a loop and the engine died. He could not get it re-started and was forced to land on a 4 lane divided highway near the airport. (of course this made the international news, primarily because of the airplane markings, but that's another story). Since then I have not been able to do any acro in my Sonex, and I am dying to try it out.

After investigation, my mechanic determined that the reason the engine died was that the g load in the pull up to the loop caused the fuel to be too rich, flooding out the engine. He figures the only way to cure this condition is to install a fuel pressure regulator ahead of the TBI. Upon looking around in the engine compartment there is not enough room on the firewall to mount the regulator, so he thinks he will have to weld a bracket on the motor mount on which to attach the regulator.

Questions: 1. Have any of you guys experienced engine flooding out doing acro? If so, what did you do to cure that problem?
2. Is installation of a fuel pressure regulator necessary?
3. If it is, would it be ok to weld a bracket to the motor mount (cross piece going side to side) to hold the regulator?

Any input you guys have would be appreciated. I am getting too old to keep waiting for my acro fix.

Ron, legacy Sonex taildragger, aerovee with aerocarb, based at KlZU