Spin testing observations - feedback requested

[Bill Dicus]

Nice video; thanks for the effort to do it and post. I wasn't able to keep track of all pitch changes leading up to the stall break or spin entry, so my impressions include some guesswork. I think the tendancy to go inverted in the first half turn may come from forcing the entry a little - i.e. hitting full rudder before the stall break has allowed the nose to "break" the horizon. Sometimes there is a natural input to increase AOA just before or at the time you expect a break to occur, producing a slight accelerated stall. This seems to be associated with a more vigorous entry and more initial roll. In IAC competition you are downgraded for this type of entry. Judges like to see the nose break through the horizon before any turn or rotation occurs. Trying this in the RV-8 owned by Wendell Foltz (delaying rudder input until nose has passed thru horizon) resulted in smooth gentle entry with no tendancy to go inverted. Try that and see if it yields a different entry. By the way, it ooked as though those two turn spins went more than two! Thanks again and keep us informed on spin behavior at various CG's and weights. Bill

[N733JJ]

Carl,
I spin my 8 on a regular basis. I have also spun a 6 and 6A.
The primary reason you are rolling inverted on your spin entries is because you are initialting the spin prior to the stall, almost a snap roll. If you wait until the buffet (I realize there is very little) or the break, you will not roll over the top as you have been.

Scott A. Jordan
N733JJ
725 hours

[zkvii]

Originally Posted by Bill Dicus

I think the tendancy to go inverted in the first half turn may come from forcing the entry a little - i.e. hitting full rudder before the stall break has allowed the nose to "break" the horizon. Sometimes there is a natural input to increase AOA just before or at the time you expect a break to occur, producing a slight accelerated stall. This seems to be associated with a more vigorous entry and more initial roll.

OK - that would sort of tally. I've actually got quite a lot of specific data from the GRT but it is difficult to really visualise it. The google earth render is pretty detailed - the attitude info is very accurate, the GPS lat/long and movement suffers from only being 1Hz (alot of movement in 1 secs)

Originally Posted by Bill Dicus

In IAC competition you are downgraded for this type of entry. Judges like to see the nose break through the horizon before any turn or rotation occurs.

So competition entry is? from the nose level with horizon with rudder netrual and as through the buffet and as a wing starts to drop, then rudder? Or starting with a more nose up attitude?

Originally Posted by N733JJ

The primary reason you are rolling inverted on your spin entries is because you are initialting the spin prior to the stall, almost a snap roll. If you wait until the buffet (I realize there is very little) or the break, you will not roll over the top as you have been.

Thanks Scott, I tried one yesterday at 55kts but was well forward CofG and seemed to be worse - hence some of the questioning..... What speeds are you using in the 8?

2 Turn - is 2 turn until initiating recovery, ends up being about 2 2/3.

Thanks for the input,

Carl

[frankh]

http://youtube.com/watch?v=rK5DiNyEuzQ

This one shows a 5.5 turn upright spin in a 7a with large rudder...Oh and opposite aileron to provoke it a little.

Frank

[fl-mike]

Nice video, thanks. Looks like you went negative g on the last recovery(?) Was that the low oil pressure annunciator that lit up?

[zkvii]

Originally Posted by fl-mike

Nice video, thanks. Looks like you went negative g on the last recovery(?) Was that the low oil pressure annunciator that lit up?

Hi - not sure which lights went on, but probably EIS (red on the LHS) (oil or fuel pressure). The other possibles are in the center locations fuel pump (FADEC auto for low pressure), Mute light would be on for the AoA disable, MFD alert for EIS also, GPS possibly just as a airspace alert. I think it was only transitant - could have been fuel sloshing around causing min fuel on the EIS.

Just looked at the logs, Oil pressure went from 69 psi to 37 psi during the 2+ turn spin just after getting to a low of .2 G. Fuel pressure was pretty stable at 36 psia the whole way through just on engine pump.

Carl

[N733JJ]

I too, generaly do "competition spins". A normal unaccelerated stall and full rudder just as the nose drops. I'm not looking at the speed (and it would be different for every plane due to instrument and installation errors anyway) but the AOA is screaming "ANGLE, ANGLE, PUSH" just as it did in your stalls on the video. The fun part is pushing to the viertical down after the spin and adding full power to set up for the next manuver (1/2 Cuban in Primary).

P.S. I forgot to compliment you on the video. Well done and it can be used to help ease the anxiety of others exploring spins.

Scott A. Jordan

[MCA]

Hard to tell exactly from the video, but if the AOA is too loud there is a volume control potentiometer in the AOA box...

Nice video, spring is here and the smell of spins is in the air again!

[zkvii]

Originally Posted by N733JJ

P.S. I forgot to compliment you on the video. Well done and it can be used to help ease the anxiety of others exploring spins.

Thank you - and you are welcome. I know I watched Dan C's spins before doing this and it helped get some idea of what to expect. Spins in themselves aren't a big problem - it is all about preparedness, practice and training IMHO.

Originally Posted by MCA

Hard to tell exactly from the video, but if the AOA is too loud there is a volume control potentiometer in the AOA box...

Hi Mark - yes the AoA is 'believably loud' as opposed to 'unbelievably loud' It cuts through everything, radio / ICS etc nicely though. The video audio levels as mentioned previously also overload a bit quickly.

Regards,

Carl

[Bill Dicus]

When I competed the judges liked to see level flight with slowly increasing pitch attitude (AOA) with no turn or bank until the nose drops through the horizon as the stall occurs; only then should rudder be added (maybe a little aileron to help begin roll) to initiate the spin. Use rudder and aileron as necessary to keep heading stable until the nose drops through the horizon. Resulting entry usually seems gentle. Forget the GRT and look outside the airplane. Hope this works for you. Bill