Spin, engine quit
Posted: Fri Apr 07, 2023 11:17 am
by Bryan Cotton
Did my first spins and rolls today. Fun! My last real acro was in a Pitts a long time ago. I have the training and need to build the confidence up. So I started off with big stalls, steep turns, and then spins.
On my first spin I only went around about a quarter turn and recovered. The engine quit and the prop stopped. I hit the button and it came right back to life. Is this a common occurrence? I had the throttle all the way back on the first one and left some in on the next two.
Video to follow.
Re: Spin, engine quit
Posted: Fri Apr 07, 2023 1:16 pm
by GraemeSmith
If you negative G’d the carb - sure - the engine might stop.
Re: Spin, engine quit
Posted: Fri Apr 07, 2023 8:37 pm
by Bryan Cotton
Re: Spin, engine quit
Posted: Sat Apr 08, 2023 6:57 am
by GraemeSmith
OK - the opposite - you might have momentarily over riched it on the pull up just before it stopped.
Sorry - not been paying attention - which carb are you running?
Re: Spin, engine quit
Posted: Sat Apr 08, 2023 8:11 am
by Bryan Cotton
GraemeSmith wrote:OK - the opposite - you might have momentarily over riched it on the pull up just before it stopped.
Sorry - not been paying attention - which carb are you running?
Aerocarb. Or I guess we call it an aeroinjector now. I did lean before I started. During my warmup at about 2G I had a stumble which responded well to leaning, so I thought the mixture was ok.
My idle is pretty low. Warmed up and on the ground it ticks over too slowly for my MFD to read RPM and I adjust manually for 900 RPM or so. I do like that setup for landing, as opposed to a 900 RPM static that is much higher on final approach.
Re: Spin, engine quit
Posted: Sat Apr 08, 2023 10:42 am
by GraemeSmith
I always lean a bit more than lean when looping or doing hard pulls. The weight of fuel in the tank seems to overpower the needle and the carb over riches.
Re: Spin, engine quit
Posted: Sat Apr 08, 2023 11:09 am
by Tnhelm
Also, in addition to spins, I have done aileron rolls, a hesitation roll, hammer head turns, half Cuban eight, loops, and steep lazy eights, all with no engine quilting issues.
Tom Helm
OneX0137
Re: Spin, engine quit
Posted: Sat Apr 08, 2023 11:26 am
by Arjay
Bryan.
We had the same problem trying to do acro with the Aerovee with aerocarb. The engine quit and Fred couldn’t get it restarted. Had to do an emergency landing on highway 316. We finally ditched the aerocarb for a Rotec tbi, but have not had the opportunity to try acro with it yet.
Ron
Legacy Sonex tailwheel, Aerovee in Georgia
Re: Spin, engine quit
Posted: Wed Apr 12, 2023 9:46 am
by Scott Todd
Is that really the carb’s fault? If its getting fuel, it works. Part of the clearing turns before doing acro should also verify the emergency landing site. A highway should usually NOT be considered.
Re: Spin, engine quit
Posted: Wed Apr 12, 2023 11:17 am
by Bryan Cotton
Scott Todd wrote:Is that really the carb’s fault? If its getting fuel, it works. Part of the clearing turns before doing acro should also verify the emergency landing site. A highway should usually NOT be considered.
I had my landing site picked out before that!
It would be interesting to learn why Ron’s engine would not restart. Mine restarted no problem. My intention is to leave a little more RPM in for spins. Not much inertia in these little wooden props.
Re: Spin, engine quit
Posted: Thu Apr 13, 2023 10:03 am
by builderflyer
That’s also why aerobatics are initually done in Phase I over an approved test area with consideration given to where an emergency landing may take place. The maneuvers tested then must be recorded and only those can be done when no longer in Phase I. Thems the rules noted in the Operating Limitations, at least in mine.
Art,Sonex taildragger #95,Jabiru 3300 #261
Re: Spin, engine quit
Posted: Thu Apr 13, 2023 10:39 am
by Bryan Cotton
Art,
My DAR said it differently. I’m out of phase 1, but until I sign off a maneuver in the aircraft logbook, I can only do them within phase 1 limitations.
I did a stall, a bunch of rolls, and my first loop today. No engine quits. Sometimes I get some hesitation at the top of the roll and sometimes not. There is a balance between pulling enough g on the top and not too much, because too much pull and you end up nose down. Oil pressure has been good through all the maneuvers.
So the first loop was scary, as I haven’t done one in 30 years and had never done one solo. But it went ok. I only pulled 3G, I’m still acclimating to the G forces.
Re: Spin, engine quit
Posted: Thu Apr 13, 2023 11:14 am
by builderflyer
Bryan Cotton wrote:Art,
My DAR said it differently. I’m out of phase 1, but until I sign off a maneuver in the aircraft logbook, I can only do them within phase 1 limitations.
Interesting…just before I received my Operating Limitations 18 years ago there was a move to unify them throughout the country as they were not all the same at the time. I thought this had been accomplished but apparently not. Having arbritary limitations in different parts of the country leads to inconsistenties and potential unfairness to those in the experimental community or to those who buy into it at a later date. Oh well…
Art,Sonex taildragger #95,Jabiru 3300 #261
Re: Spin, engine quit
Posted: Thu Apr 13, 2023 5:17 pm
by GraemeSmith
So I was issued new OL’s when I changed my tail number. And while I was at it moved my Phase 1 area from the original builder’s (in SC) to my area in RI.
The inspector from the Boston FSDO commented that these were the “standard template we have been introducing - including the Phase 1 test areas which are worked out already based on your home airport”.
Here is what mine have to say about acro. The middle paragraph is a little unclear - talking about flying acro in Phase II.
But the third para makes it clear that establishing acro maneuvers is done in Phase I (Click on image to see in full)
Re: Spin, engine quit
Posted: Thu Apr 13, 2023 5:27 pm
by Bryan Cotton
Going from phase 1 to phase 2 was a logbook entry. What my DAR was saying was you make a logbook entry going back into phase 1, do and document the maneuvers, and you can go back into phase 2. So I think we agree that it is a phase 1 activity - but the disconnect is how we switch phases.
Re: Spin, engine quit
Posted: Thu Apr 13, 2023 5:56 pm
by GraemeSmith
“Put aircraft back into Phase I in order to test XXXXXXXXXX” Date, Signature, Certificate Number.
Re: Spin, engine quit
Posted: Thu Apr 13, 2023 8:17 pm
by Bryan Cotton
Yes, although I’m doing:
“Put aircraft back into Phase I in order to expand aerobatic envelope” Date, Signature, Certificate Number.
“XXXXXXXXXX maneuver(s) demonstrated successfully. Put aircraft back into Phase 2.” Date, Signature, Certificate Number.
Re: Spin, engine quit
Posted: Fri Apr 14, 2023 9:54 am
by builderflyer
Graeme, my “OL” look a lot like your “OL” so maybe there is now some consistency across the country and across time. The only other comment I have is that my insurance policy becomes invalid if I place my Sonex back in Phase I, something I hadn’t noticed until after testing four of Prince’s props under Phase I. Don’t know if all policies have that same language but this could be of concern to some.
Art,Sonex taildragger #95,Jabiru 3300 #261
Re: Spin, engine quit
Posted: Sat Apr 15, 2023 10:30 am
by Arjay
Bryan:
Do you float (at zero g) across the top of your loop? No engine hesitation there? How about when pulling g’s on the back side and finish of the loop?
Ron
Re: Spin, engine quit
Posted: Sat Apr 15, 2023 12:11 pm
by Bryan Cotton
Arjay wrote:Bryan:
Do you float (at zero g) across the top of your loop? No engine hesitation there? How about when pulling g’s on the back side and finish of the loop?
Ron
Ron,
From my G meter tell-tales I got as low as a half-G. I think during one of my rolls this morning I managed 0G. It sounds like the engine is hesitating on the up line and across the top but on the back side/finish it is ok - but I’ve got power out on the downhill run.
I did about 5 loops this morning. Still getting acclimated. I had been finishing loops a little higher than I started. I have been doing the dive to 140, which requires a lot of throttle reduction to stay below 3400 RPM. I level off, note the altitude, then pull. I’ve been doing about 3.5G. By vertical I am back to full throttle and I pull it off as I pass the top.
Re: Spin, engine quit
Posted: Tue Apr 18, 2023 5:39 pm
by mike.smith
Been doing acro with my AeroVee and AeroInjector for 9 years. Never had it quit. I’ve had it burp once doing a hammerhead when I got to 0 g’s. I’ve done up to 5-turn spins. I’ve never reset my carb needle in 8.5 year. I’ve been lucky enough to have the AeroInjector be in the absolute sweet spot for all that time. I use the mixture all the time. So in the summer I NEVER push the carb to full rich. In fact, if I try to do that on take-off the engine will stumble. So I keep the mixture out about an inch in the summer. In the winter I push it to full rich for take-off, but lean after that. In the air I lean aggressively. I never reset the needle because of the climate or temperatures.
All of that is to say, if you get the AeroInjector dialed in to how you operate, it works like a champ. If you treat it like an OEM airplane engine, my experience is you are going to have issues. You have to see what works for you in your climate, and what you do with the airplane, set up the AeroInjector accordingly, and operate the engine within those parameters.
If the engine cut during a spin, my first guess would be the mixture/needle is too lean. I don’t think I ever pull the throttle to “full” idle when I’m doing spins or any aerobatics. I’ve always got something in there, even if not a lot. Maybe that’s something to try.
Re: Spin, engine quit
Posted: Tue Apr 18, 2023 6:25 pm
by Bryan Cotton
Thanks Mike. I have not had another engine quit. I’ve had stumbles if I go a little negative on the roll. For my loop this morning it was happy. Split Ss were no problem. Hammerheads coming up soon.
I have been going all the way to idle downhill on the loop. I haven’t done more spins but plan to leave some throttle in.
Re: Spin, engine quit
Posted: Tue Apr 18, 2023 7:26 pm
by Scott Todd
I’ve owned 3 Aerovee’s and flown two others. I currently have two flying including my new Onex. I have about 150 hours in all of them. ALL of them have been on the rich side. They definitely need leaned on taxi or will stumble on takeoff. Never had one quit but the stumble can be alarming if not ready for it. I always use 100 LL AvGas. I’ve only ever done 1 turn spins. I generally don’t do Aerobatics and when I do, keep them to a minimum.
I follow everything Mike says. Done aerobatics in all of them and never had one quit. I tend to avoid 0g’s and keep everything positive. I love the simplicity of the AeroInjector. It just work. Sure, it may not be efficient and it burns more fuel than the Rotax’s, but I’m happy to give it a fresh oil change ever 20 hours or so and feed it as much 100LL as it wants with me usually flying it on the rich side. I’m one of those people that NEVER say a word about gas prices. I think the fuel price gets lost in the noise of all the other expenses associated with Aviation. You just can’t beat 140mph at 4gph for the price.
Tune it a tad rich and it will not let you down 
Re: Spin, engine quit
Posted: Tue Apr 18, 2023 8:01 pm
by mike.smith
I’ve put a number of aerobatic flights on YouTube:
https://www.youtube.com/@mikesmith208/videos
https://www.youtube.com/watch?v=ctzIi77rxok
Re: Spin, engine quit
Posted: Wed Apr 19, 2023 9:05 am
by Onex107
I agree with Mike Smith on the aeroinjector. Once I insulated to eliminate the burps, and had the needle dialed in, I never touched the needle adjustment again for eight years. It’s not a carburetor, the mixture has to be managed, but it’s so simple. My adjustment acted exactly like Mike’s. Full rich, stumble on takeoff. An inch out at full power and lean to a higher egt at cruise. I didn’t do a lot of acro. Remember guys, at negative G’s, depending on your tank vent setup, you could expel fuel. Don’t get it on the windshield. Bad, bad. Replacing a windshield isn’t easy.
Re: Spin, engine quit
Posted: Wed Apr 19, 2023 11:51 am
by Bryan Cotton
mike.smith wrote:I’ve put a number of aerobatic flights on YouTube:
https://www.youtube.com/@mikesmith208/videos
https://www.youtube.com/watch?v=ctzIi77rxok
I subscribed a while ago. Thanks for posting these!
Re: Spin, engine quit
Posted: Thu Apr 20, 2023 9:33 pm
by mike.smith
Onex107 wrote:Remember guys, at negative G’s, depending on your tank vent setup, you could expel fuel. Don’t get it on the windshield. Bad, bad. Replacing a windshield isn’t easy.
I did the up/down vent. It goes up a few inches above the cowl, turns 180 degrees down, then goes down the firewall to an exit at the bottom of the cowl. During some of my first acro, I saw fuel spit on the canopy. I didn’t do any acro again until I made the new vent. As a bonus, I can get 17 gallons in my tank without any of it siphoning off.