Spin. Engine quits. Why?

[spatsch]

Here is a video of a 47 turn (I think ...) spin:

http://www.spatscheck.com/oliver/Spin.mp4

the engine quits because fuel gets pushed to the outside of the tank so the engine starves. Prop stops turning couple of turns later because there is little airflow over the fuselage (in the correct direction that is).

Starts right back up after the prop starts spinning again. I was a bit surprised though how fast I had to get for the prop to start spinning on it's own. Didn't feel like using the starter as I wasn't sure it wouldn't damage something if I used it in flight at high speed and I had plenty of altitude to work with... .

Oliver

[TX7A]

Wow Oliver...that made me dizzy just watching that.

Let's see....what did I do with that big zip lock bag....ugh!

[jrs14855]

For the first video the spin is significantly flatter than I would expect. Note a little outspin aileron at the start increasing slightly as the spin develops. Any significant outspin aileron(left stick in this case) will flatten the spin.
I think the disrupted induction airflow is the likely cause of engine stoppage.

[isosceles]

I have a similar spin characteristics in my Giles G-200: the combination of a flattish spin and a lightweight prop may cause engine stoppage. I just add a tad of power after it breaks and this solves the mystery. It has nothing to do with the fuel starvation or a particular nose-down attitude. I've heard Extra-200 has similar behavior

[RV8Squaz]

Marabou,

What altitude are you doing your spins at and where is your mixture set? In the beginning my engine was quitting also. When doing spins from 5000? or higher, I finally figured out that my mixture was too rich at altitude when I pulled the throttle to idle. After doing a full throttle climb with the mixture full rich, I began to lean the mixture after pulling the throttle to idle. The engine stopped quitting after adopting this technique.

Also, in competition aerobatics, a commonly used technique is to go to full throttle before rotation stops to increase airflow over the vertical stabilizer and rudder. This helps stop the spin on an exact heading.

Good luck!

[Marabou]

Originally Posted by RV8Squaz

Marabou,

What altitude are you doing your spins at and where is your mixture set? In the beginning my engine was quitting also. When doing spins from 5000? or higher, I finally figured out that my mixture was too rich at altitude when I pulled the throttle to idle. After doing a full throttle climb with the mixture full rich, I began to lean the mixture after pulling the throttle to idle. The engine stopped quitting after adopting this technique.

Also, in competition aerobatics, a commonly used technique is to go to full throttle before rotation stops to increase airflow over the vertical stabilizer and rudder. This helps stop the spin on an exact heading.

Good luck!

I start at about 6000. 10 turns later I still have at least 3500. And I always lean even at lower altitudes and even while climbing if CHT allows.

My main question is regarding your advice to go to full throttle before rotation stops. I?ve got some flat spin training with three different instructors in other ?a bit more aerobatic? aircraft then RV. One way to enter flat spin I learned is just go to full throttle right after you entered regular spin. Plane immediately raises the nose and here you are. I tried it in RV but did not succeed. Actually I couldn?t induce flat spin at all using any technique. Possibility of flat in RV had been discussed here earlier. My guess it is nearly impossible at least very difficult due to nose heavy nature of RV. A few hundreds of pounds behind the back will definitely help but go flat is not the goal. It just would be nice to know how safe it is to apply full throttle at recovery.

[spatsch]

Originally Posted by isosceles

I have a similar spin characteristics in my Giles G-200: the combination of a flattish spin and a lightweight prop may cause engine stoppage. I just add a tad of power after it breaks and this solves the mystery. It has nothing to do with the fuel starvation or a particular nose-down attitude. I've heard Extra-200 has similar behavior

Now you got me intrigued. I was pretty sure it was fuel going to the outside as I can reproduce the same effect if I do 6-8 rolls in a row (compared to the airplanes you mention I don't have inverted fuel). Guess I have to go flying again and try this ... .

Oliver

[Marabou]

Originally Posted by spatsch

Here is a video of a 47 turn (I think ...) spin:

http://www.spatscheck.com/oliver/Spin.mp4

the engine quits because fuel gets pushed to the outside of the tank so the engine starves. Prop stops turning couple of turns later because there is little airflow over the fuselage (in the correct direction that is).

Starts right back up after the prop starts spinning again. I was a bit surprised though how fast I had to get for the prop to start spinning on it's own. Didn't feel like using the starter as I wasn't sure it wouldn't damage something if I used it in flight at high speed and I had plenty of altitude to work with... .

Oliver

Nice video Oliver! Haven?t seen it before. You rotate to the left. I carefully measured rate of rotation to the left and to the right. In my case it is 1,7 seconds to the right and almost 2 seconds to the left. And altitude loss is higher spinning to the left than to the right for the same quantity of turns. But I measured it with prop still spinning. May be there is no difference once prop had stopped.

[spatsch]

Originally Posted by Marabou

Nice video Oliver! Haven?t seen it before. You rotate to the left. I carefully measured rate of rotation to the left and to the right. In my case it is 1,7 seconds to the right and almost 2 seconds to the left. And altitude loss is higher spinning to the left than to the right for the same quantity of turns. But I measured it with prop still spinning. May be there is no difference once prop had stopped.

Good question. I never measured it that precisely. It does seem that spin entry to the right is quit a bit slower but I never timed that precisely either.

Oliver

[isosceles]

Originally Posted by spatsch

... I was pretty sure it was fuel going to the outside ... .
Oliver

Not likely in my case. My spins are actually slower than the rolls and I have a header tank with a fresh flop tube in it. My impression is that it's caused by a funny airflow around the prop in the spin. Tail slides are also known for making the engine stop for the same reason.