Spin and recovery characteristics of light twins

[hugh flung_dung]

Whilst I've no intention of deliberately spinning a light twin, it would be interesting to understand how the spin and recovery characterstics might differ from an SEP. Do we have anyone here with spin experience on MEPs, or on straight-winged aircraft with and without wing-mounted stores or tip tanks?

I've done a lot of spin and aeros teaching in SEPs and assume that mass on (straight) wings (so that A>B) would lead to a flatter stable spin with a high yaw rate and not too much roll. In the absence of other guidance I assume that recovery drills would be standard, with use of power on the inside as a "last ditch" idea. Any real-world experience or advice?

HFD

[rodthesod]

Hi HFD,

There may be a few posts on the 'Spinning an Airliner' thread that may interest you, and you can PM me for more on the MU2 spin if you wish.
rts

[hugh flung_dung]

Thanks RTS, PM Sent.

HFD

[Teadriver]

No advice worthy of the name. In my experience the theory's one thing but the variables between individual aeroplanes, and the large number of factors that affect spinning characteristics in addition to B/A ratios, means that it's difficult to predict anything from a first principles look. For example, when I was at Boscombe Down in UK I did loads of spinning in the Hunters they had there, specifically configured for spinning. There were 4 aircraft - 2 two-seaters and 2 single-seaters and every spin (left, right, erect or inverted) was different, although in theory they should have been similar.

[Creaser]

If you believe Diamond aircraft their Twin Star is set to become the most popular trainer.
I understand that they are working on a stall kit for one of the survelliance models to enable safe 60 knot missions.

Would an engine failure at 60 knots in a (tight as possible) orbit something that would be safe to train in standard or survelliance models.

How much height would one lose in the recovery assuming a full load?

Creaser

[On-MarkBob]

During some air-testing I have spun a number of light twins, including Piper Seneca, Aztec, Islander and some more. The noteworthy thing was that they don't spin well at all, the manufacturers have done well in their designs. Most seem to want to, but as soon as they nose down it just spirals away once you relax the controls. You have to work hard to keep it there, if they stay at all. Most successful were the high wing types, like the Islander. I also had to spin a Cessna 337 (Pushmepullyou) with a grid of lights attached! the CAA were concerned that the grid might cause some unpleasent control problems, there was no problem at all and it span about as well as a 182, ie hardly at all. I would not recomend the use of any power in the spin as it would tend to flatten out the spin, regardless of which side. Remember that the aircraft is pitching up rolling and yawing at the same time, to execute the recovery the idea is to place one of the aircraft axis over the spin axis. The one we use of course is the longitudinal axis and this is why we push the stick foward. Using the rudder then stops the yaw. Some Aircraft are quite exacting and need significant nose down so that the axis alines almost exactly, any power might just prevent this happening as you might find there is insufficient down elevator to compensate. I hope I have been helpful.

Bob

[hoggsnortrupert]

ZK HNZ : Loaded with fifteen meet bombs, over Wairarapa I allowed myself to get distracted by the jumpmaster "demanding" my attention whilst slowing down to 80kts at 10500 ft,approaching the DZ, the other 14 were exiting the cabin and hanginging on where ever they could and it stalled and flicked due to the amount of rudder I was applying to counteract the packs of meat disturbing things.
It really flicked well, much the same as in training in the 152 aerobat some years prior.
The nose was pretty well pointed at tera firma.
"No stall warning was heard".
They all dissapeared rather quickly, power was pulled back to idle, the control column checked forward, and opposite rudder applied, until rotation stopped, It recovered really well, and all under control again by 9000 ft, from memory I think it did approximitely 1-1.5 turns.
Not something I would recommend, and am a firm believer that dropping meat bombs ( Skydivers) is not something I would like to do again as they "are" different.:}
Not my flashest moment, but I learned to tell the jump master's to shut the :mad: up.
HSnort.

[hoggsnortrupert]

Sorry I think that should be SNZ.
HSnort.