Spin testing observations - feedback requested

zkvii · #1 04-23-2008, 10:24 PM

Hi,

Last week I did some spin testing on VII (RV 7A - large rudder) as part of the later stages of flight testing. I've been comfortable with the stall / power on / off / bank etc for a while and slowly worked up with 1/2 turn, 1 turn, 1.5 turn and 2 turn spins. First observation which I was expecting from the reading was 2 turns starts to really wind up - quite 'exciting'

. That said it all did what it was meant to and responded nicely to standard recovery.

A short video of the stalls / spins - http://www.youtube.com/watch?v=xVMWKFI9gb4 - excuse the lack of music / my chatting - it was for flight testing!

I'm initiating with full aft elevator and full left boot at 60 kts in a slight nose up attitude. 1 turn seems to be about 400 feet.

Yesterday I also did some more .5 and 1 turn with more foreward CofG ( 1428lbs @ 81") . It seems to my limited experience to swing through even further to quite an 'inverted' position - is this others experiece too? The swing through is more than I was expecting.

As an alternative - if you have google earth installed ( http://earth.google.com ) a mini animation clip at 10msec is available at http://www.rvproject.gen.nz/kml/ZK-VII_2turn_spin.kmz - this shows nicely the attitude changes.

Hope to get feedback from others experience - particually the initial 'inverted / on the back' attitude before I start moving the CofG further aft towards the aeros aft limit.

Regards,

Carl

Jim P · #2 04-23-2008, 10:33 PM

Based on the video, looks like you had enough after the 2nd turn.

How did the GRT avionics hold up during the spins? Any problems?

Jim

kevinh · #3 04-23-2008, 10:35 PM

Hi Carl,

I'm no great expert but I do practice spins every couple of months (around oil change time preferably). From looking at your video your spins look identical to the view I'm used to seeing from my 7A (with the later rudder).

Looks like you are doing a good job on your flight testing.

zkvii · #4 04-23-2008, 10:53 PM

Quote:

Originally Posted by Jim P

Based on the video, looks like you had enough after the 2nd turn.

How did the GRT avionics hold up during the spins? Any problems?

Jim

GRT goes great - no problems - that is what is providing the raw data for the google earth rendering

The 'next generation' GRTDecode will be improved (when I get a few spare weeks.....)

2 Turns - enough for one day - then went onto some loops and rolls

zkvii · #5 04-23-2008, 10:56 PM

Quote:

Originally Posted by kevinh

Hi Carl,

I'm no great expert but I do practice spins every couple of months (around oil change time preferably). From looking at your video your spins look identical to the view I'm used to seeing from my 7A (with the later rudder).

Good - have you tried forward vs aft CofG - any differences? Next spins need to be further aft and I'm just being cautious....

Quote:

Originally Posted by kevinh

Looks like you are doing a good job on your flight testing.

Thanks - any day for flying is a good one. Still working on temps but I think part of it is me expectin too much! I have learnt lots about delta pressures across the engine and have instrumentation for it and the various mods I'm trying.... another thread another day.....

Carl

Ironflight · #6 04-24-2008, 06:04 AM

Hi Carl,

Your spins look a lot like what I saw in the -8 during my own phase 1 testing - I haven's spun a -7 myself, but they seem pretty close from your video.

Your program looks like it is progressing well, and should be an example for those folks who think that Phase 1 is "flying the same hour 40 times". The combination of GRT-recorded data, video, and voice recording sure makes it a lot easier to build a database than having to do it with pencil and paper, doesn't it?!

I wish I'd thought of mounting a camera like that during my own Phase 1, but the video camera I had at the time would have taken some engineering time - if I'd had the little SD400 I have now with a big memory card, it would have been a piece of cake, and I'd recommend that to anyone - do you have a picture of your camera mount you could share? I'd like to have that for my Flight Advisor files.

Congrats, and keep up the good work!

Paul

zkvii · #7 04-24-2008, 06:38 AM

Quote:

Originally Posted by Ironflight

Hi Carl,
Your spins look a lot like what I saw in the -8 during my own phase 1 testing - I haven's spun a -7 myself, but they seem pretty close from your video.

Does the 8 go on it's back too? any CofG changes?

Quote:

Originally Posted by Ironflight

Your program looks like it is progressing well, and should be an example for those folks who think that Phase 1 is "flying the same hour 40 times". The combination of GRT-recorded data, video, and voice recording sure makes it a lot easier to build a database than having to do it with pencil and paper, doesn't it?!

We are basically finished with phase one - I can sign out the flight testing when I'm ready, but currerntly still playing with the cowl inlets / cooling. It becomes significantly more difficult for that type of maintenance once it is a 'fully fledged aircraft' in NZ so I'm holding back a little. The actual flight testing has been pretty smooth / easy, the 25 hours would have been plenty, but with the oil cooling problems early on and air inlet development work that has meant we chewed quite a few hours quickly - nearly time for a 50 hour check! We also had a couple of hours of X-country partly just to stretch the legs and learn a bit more about the systems. My piloting confidence has increased along with the confidence in the aircraft - very much a 'growing phase' in all ways.

The GRTDecode stuff has been great (when I remember to start and stop it!), hopefully GRT will get the auto start / stop logging working soon. GRTDecode needs quite a bit of work, I've started with development of a proper GUI and the Google earth representation will improve in the next version. I'm currently using quite a lot of Excel charting / plotting functions, it would be nice to integrate that too - but difficult to make flexible enough for everyone. I'd also like to be able to keep a continous timeline of the plane, rather than just a single flight. The FADEC engine log is great - provides complete engine history from hour zero and has helped in the diagnostic process more than once. Biggest risk for us is too much information and worrying about 'normal' things......

I still find logging on a knee pad the first cut of the information - things like % power, DA and TAS aren't trival to re-calculate and it is simpler to record with pen/paper and voice on video.

Quote:

Originally Posted by Ironflight

I wish I'd thought of mounting a camera like that during my own Phase 1, but the video camera I had at the time would have taken some engineering time - if I'd had the little SD400 I have now with a big memory card, it would have been a piece of cake, and I'd recommend that to anyone - do you have a picture of your camera mount you could share? I'd like to have that for my Flight Advisor files.

Video - something I wanted from the start, the biggest problem has been audio - the camera has auto gain on it and overloads very easily. It is wired to the passenger lines on the GMA340.

The photo above shows the tray/bracket it sits in - there is a location peg on the bottom and a screw upwards to hold the camera down. The base pivots at the back and fixes at the front which meant the sky / panel can be adjusted. It works quite well even with two people. I'm using just a basic Canon DV camera, but seems to hold up to at least 4 G

. The 43 hours of flight testing, most have been video'd - about 400GB of raw footage. I'll try to get a photo of it with a camera / more details for you when I'm next down 'big shed'.

Regards,

Carl

grantcarruthers · #8 04-24-2008, 07:02 AM

Nice video and thanks for taking the time to create, edit, and share.

What kind of speeds are you seeing in the recovery??

Thanks

zkvii · #9 04-24-2008, 07:10 AM

Quote:

Originally Posted by grantcarruthers

What kind of speeds are you seeing in the recovery??

I think you can hear me calling them and the Gs on the pull outs. From top of my head 130 ish knots and 3 G from the 2 turn spin. It was slower than I feared, I'm sure nose down it will pick up quickly, but it was a simple, stick center, oposite rudder, count 1, roll stopped, pull gently (already in the 90+ kt range), wait for the horizon / positve climb / attitude, add power.

Not sure I'd want to spin power on!

I'm guessing right boot might be a little more exciting too....

Carl

kevinh · #10 04-24-2008, 09:06 AM

Quote:

Originally Posted by zkvii

Good - have you tried forward vs aft CofG - any differences? Next spins need to be further aft and I'm just being cautious....

I don't regularly do spins at the forward and aft limits, but I did do them back in my phase one. I don't recall the differences - to me they all seemed quick but recoverable using the regular technique.

My recent stuff has just to stay current in case I botch my beginner acro moves.