Topic: Spinning

[Brent]

I was thinking about the recent topic concerning spinning.  I haven't felt the need to spin my Chipmunk yet, but I do have some thoughts to throw into the pot for consideration.

When I started flying, spinning was a requirement for the PPL.  I spun, (span?) the Tiger Moth and Auster with nary a thought.  When in military flying training I spun the Jet Provost and Vampire quite happily while sitting on one of Mr. Martin Baker's masterpieces, because it was required as part of the training and I was young and immortal. Incidentally the Vampire spin was quite 'energetic' to say the least.  

After watching Bill Bedford I just had to spin the Hunter to see what that felt like...........Of course while sitting on one of Mr. Martin Baker's products.  Although I hadn't really thought of trying it deliberately, I found myself in a spin in a Supermarine Scimitar.  This was not due to an enquiring young mind so much as ham fistedness, but in spite of that recovered without too much drama  ............while sitting on my favourite seat.  I practiced fully developed flat spins in the Yak 52....while sitting on....well you get the picture!

I even tried spinning a DC 9 MD 80....in the simulator!  Without a prachute this one time.  Now there was an interesting ride, but the seat in the simulator never did get more than ten feet or so off the ground regardless of what the altimetre said, so I took the risk without the parachute.
 
I think that you may see some kind of consistency here.  In my opinion a parachute makes a very comfortable seat when deliberately spinning.  In fact I can think of no reason deliberately to allow an aircraft to stabilise into a fully developed spin unless it is a precision aerobatic manoeuver.  Now before we all explode into denial, I should say that I also think that we should all practice recovery from an incipient spin assiduously.  We should become very comfortable with it and instinctive in our method of recovery.  

The problem with spinning is that it only takes the smallest mistake to make a recoverable spin .....non recoverable.  The Hunter for example has a white dot on the panel to indicate the neutral aileron position.  If you don't get it quite right, then the aeroplane very well might not recover.  I believe that most unrecoverable Hunter spin accidents were probably due to this.  If that white dot falls off the instrument panel, the aircraft is unserviceable......At least it was in my day.

Same thing with the Yak.  If there is still a little power left on...........maybe it will take longer to recover....or not.  If it is slightly misrigged....it may not....If there is a just a little 'OUTspin aileron held, it probably will not recover.   An aircraft may well have recovered on the flight before, but next time there may be a heavy passenger in the rear cockpit rather than being solo.  A very close friend of mine killed himself and another friend for this reason in a Harvard.  Silly really.  He and I had been practicing spins quite happily in that same aircraft, but not with full tanks and a 100 pound heavier passenger in the back.  He didn't allow for that.

There are a couple or so of basic flight truths that I like to remember.  I am sure that all here are familiar, but it doesn't hurt to think about them occasionally.
 
1.  An aircraft needs to stall to spin.
2.  An aircraft normally needs to yaw to spin.
3.  At zero 'g' an aircraft cannot stall regardless of airspeed. (or lack thereof)
4.  When an aircraft will not recover, and in deep doodoo, lost for something to do, thinking about mum or your labrador, try feeding in 'in spin' aileron.  It probably won't hurt and might help.  In fact in a Yak in a flat spin may not recover at all without inspin aileron, so it is worth remembering that.  In a normal aircraft, ADDING POWER WILL NEVER HELP SPIN RECOVERY !!

5.  The Royal Airforce teach a recovery method which to my mind has not been improved upon......................despite attempts by others.

Undercarriage and flaps UP! (Difficult in the Chippy, but do your best)
Throttle closed
Ailerons neutral
FULL opposite rudder
Stick forward until the spin stops. Note.  Don't 'slam' it forward, the aeroplane could well think that is naughty and revert into an inverted spin to teach you to be more polite.
   
Think of the movement of the forward stick as stopping the rotation if you like.

Just before it comes out of the spin some aircraft increase the rate of rotation considerably which can be rather disconcerting.  As soon as the rotation stops, neutralise the rudder immediately otherwise you might well find yourself in a spin in the opposite direction, which will be very disappointing. Particularly close to the groud.

As I say, I don't like fully developed spins for fun, and see no point in them...................incipient spin recovery.....now there is a thing that  is very important.

See you at Sywell I hope,  Brent...G-CDWF

[Rod Blievers]

Hi Brent:

What an interesting and thought provoking posting!

Could I add a non-Chipmunk related note of caution? While you may have recovered from your spin in the MD-80 Simulator, bear in mind that unless this type of aircraft was actually spun during the flight test programme (an extremely unlikely event),  there is no actual data to cover this area. The implication is that the simulator’s handling reflects what the programmers THINK might happen, not what the aircraft might actually do if pushed into this corner. This limitation applies to virtually every airline type simulator; within the normal envelope plus a margin the handling very accurately reflects the real aircraft but outside these parameters the handling is an approximation…

Turning to the Chipmunk, I completely agree that the standard RAF recovery as quoted is THE spin recovery technique and should always be the spinning pilot’s first option.  However, I note that the “RAF Flying Instructor’s Handbook – Chipmunk T.10” (A.P. 3225C) also discusses Emergency Recovery techniques, should this recovery technique fail to produce the desired effect. I think this is worth quoting in full – note the cunning use of the word(s) “may”:

“15. Before being authorized to practice spinning solo the student is to be briefed on the action to be taken in the event of the aircraft failing to recover from the spin within four or five turns after the application of normal recovery action.

 16. The following emergency recovery actions should be applied in turn until the aircraft recovers:-
   (a) Use the ailerons by moving the control column into the forward corner opposite the rudder.
   (b) Move the control column fully back and hold it there for five seconds then move it fully forward.
   (c) Move the control column sharply forward, pause a second; fully back, pause a second; fully forward. This is to induce a rocking motion and may be aided by opening the throttle as the column is moved forward and closing it as the column is moved backward.
   (d) Lower the flaps. This action may produce a decisive change for the better, or it may have a bad effect. Therefore it should not be used until all other methods have failed.”

Food for thought…..

Cheers,

Rod

[Brent]

Absolutely right Ron.  As far as spin recovery is concerned of course I agree with you completely, follow the RAF recommendations.  Notice that reading between the lines, the idea of lowering the flaps is just an further idea borne of desperation.  As they intimate, it might make it worse.  Presumably what they are trying to do is to change the airflow around the tail area.  A kind of, "Who knows, it might work, try it mate" thought.  Pumping the throttle which is what they are suggesting, is only going to tend to flatten the spin which is the 'rocking' they mention.  The problem is that I suspect that no one ever actually saved an aircraft  reluctant to recover by using this method, and in the meantime, while doing this one would be certainly be delaying the recovery, (and delaying the decision to get out).

Of course, using my philosophy, the only reason the thing is in a developed spin in the first place is because for some reason it failed to recover from the incipient phase, so I know that something is wrong with my day immediately!

Please disregard the slightly tongue in cheek comment regarding the    MD 80 simulator.  Perhaps I should have mentioned that in fact while you are correct concerning simulator modelling not necessarily being identical to the real thing once outside the design envelope, the thing gave us quite a ride!!  I certainly didn't want to suggest that we all go out and try it in the real thing!  
Typical of 'T' tails, we did not recover.  It was very difficult to get it into a spin to start with, but once spinning, the motion was violent and didn't stop.  As I say, my seat was only ever 10 feet of the ground so I felt reasonably brave about the whole experiment, which was caused by having a spare 20 minutes or so to play!  

Regards, Brent

[Rod Blievers]

My point regarding simulation is that both the difficulty you experienced getting the simulator into a spin and (more importantly) the "ride" you then experienced may not accurately reflect what a real MD-80 would do.

Not only is there a likely modelling/reality disparity due to a lack of actual data, but you're also running into physical limitations of the simulator; the jacks may not be able to reproduce the sensations as they would be perceived by the pilot and almost certainly the buffetting in reality would be far more violent than the simulator mechanisms can reproduce...

Cheers,

Rod.

[Brent]

I am sure that you are correct Rod, and certainly more qualified to discuss simulator technology than I, but I have had some very violent rides in modern simulators.

My only additional comment might be that it was (I think) a level 6 sim from Raytheon(?)  which were superb.  In any event the only airliner spin of which I have any knowledge was a 727 some years ago.  Bad situation, but as far as the violence of the ride was concerned, from all accounts from the cockpit voice recorder it was a relatively quiet ride all the way down.  

In any event as I said, that was just something of a throwaway tongue in cheek reference.  The main thrust of my rambling was that I don't see any point in leaving an aircraft in spin until it becomes fully developed.  Unless of course there is some additional requirement...............and of course as might have been gathered, I would be very reluctant to allow a spin to become fully developed unless sitting on a good parachute.

I have done a fair bit of developed spinning in various configurations in a Yak 52.  Now that is a totally honest aircraft, BUT from a flat spin one might do well to have a chat with someone with experience on type!  Otherwise a lot of additional precious altitude will be used.

But then I have just found myself considered by some rude folks to be an old dinosaur of a pilot.....Who knows, they might even be right.

Cheers,  Brent