My loops need help!

Halhayden

Halhayden

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Joined
Aug 4, 2021
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Location
Prescott, AZ
Hey guys & gals -

I’ve been practicing a few simple aerobatics after getting some instruction. My aileron rolls are finally getting better but my loops need some work. I’m entering the loop at 140 mph but I’m hearing the stall horn at the top and falling out a bit sideways. I tried pulling harder back on the way up to get over the top with more speed but still not great.

Any thoughts?

Thanks!
 
Try entering at 150? I don't do loops any more, but my Decathlon does a nice Immelman with 140mph entry.
 
One of 3 things:
1. Not firm enough initial pull. Should be 3.5G.
2. Not increasing pull as you go thru vertical and speed decreases.
3. Not relaxing pull at key point (30 deg past inverted) to float over top.

I'm guessing #2. That is easy to forget.
 
@Halhayden what kind of plane?

Like Ed said, if you pull and then hold the stick fixed you won't come over the top with a round arc. You have to pull and then increase the back pressure until you near the very top at which point you release the back pressure and try to float it over the top before letting the nose drop on its own which you then supplement through about the 270 degree mark where you should be pulling again to get yourself back to level at the altitude you started at.
 
That’s what I want. Any time you want to swap engines, props, and paperwork even, you too can have a 180 Decathlon.

I think the guys are right - you might not be pulling hard enough. Once inverted you need to ease off to avoid a banana-shaped loop.

Since I am not an aero expert, I can get away with telling you that, in my loops of yore, I looked straight ahead and up. That kept my loops in a vertical plane. The pros look out the side window - wait until you get really good to do that.
 
Halhayden said:
Thanks guys! It’s a 160 hp decathlon. I will try your suggestions and report back.
Click to expand...

I had a 160 Decathlon. Not a common configuration. Was a field approval of high comp pistons on a 150 CS. Flew very well, nice balance of power and light weight. You should have no problem looping with that aircraft.

Your entry speed is sufficient, as long as your pull up is firm. Don't bleed too much energy with a tentative pull. Set entry speed, check straight&level/altitude, then PULL! Look at your G meter and confirm you are pulling at least 3G, with 3.5G preferable. Look left and track your wing angle with the horizon. Keep tightening up the pull as you go through vertical. When you hit the key point at 30 degrees past vertical, gradually relax the pull so that the stick is roughly neutral as you come through inverted. Look up through the greenhouse roof and find the horizon. Level your wings and correct heading with rudder as needed. Let the airplane float over the top with just a little positive G, not quite zero, then let it start to find it's own way downhill on the backside. As you go through about 45 degrees inverted down the backside, tighten up the pull to roughly mirror what you did coming up. Ease off just a bit in the last 7/8 so your pull out is the same G as your pull up. Try to finish at the same altitude, and feel for that bump when you hit your own propwash right as you level out.
 
Well I got another session with my instructor and it turns out that I was pulling TOO hard at the top of the loop, causing an upside down stall and crazy spin. I had incorrectly thought that when I was at the top of the loop and heard the stall horn, pulling to get the nose back down toward earth would increase the airspeed and alleviate the impending stall. Guess not, because when I followed his instructions to ease up on the stick as I heard the stall horn, we continued over the top into a nice finish.

This is fun to learn but I’m having trouble getting my head around the concept that pulling the nose down while inverted caused the stall to worsen. What’s going on here… accelerated stall?
 
Halhayden said:
Well I got another session with my instructor and it turns out that I was pulling TOO hard at the top of the loop, causing an upside down stall and crazy spin. I had incorrectly thought that when I was at the top of the loop and heard the stall horn, pulling to get the nose back down toward earth would increase the airspeed and alleviate the impending stall. Guess not, because when I followed his instructions to ease up on the stick as I heard the stall horn, we continued over the top into a nice finish.

This is fun to learn but I’m having trouble getting my head around the concept that pulling the nose down while inverted caused the stall to worsen. What’s going on here… accelerated stall?
Click to expand...
Think in terms of angle of attack. The harder you pull, the greater the angle of attack. Relax the stick and your angle of attack is reduced.
 
Thanks Ed! Just out of curiosity, why not pull the power back on the downhill to slow the increasing airspeed and make it easier to pull up?
 
1. It's not necessary.
2. The bottom won't be round.
3. You'll give up energy.
4. You won't learn the essential aerobatic skill of using G loading to control speed buildup.

It really comes down to what your goals are. If you just want to go up, flop around, and call it acro, then you can do it however you want.

However, if you see aerobatics as a continuous process of learning to fly increasingly challenging sequences with precision, then you need to learn to be comfortable pointing at the ground with full power.

Aerobatics is all about energy management. You are constantly converting kinetic energy (airspeed) into stored energy ( altitude) and vice versa. Up, down, up, down. Slow, fast, slow, fast. While you are doing that, you are losing energy to drag. You keep the power in to recapture that lost energy.
 
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