Intentional spinning - Speedtwin E2E Comet 1

[Skeeve]

Hello All,

in my research into aerobatic certification, I did stumble upon the Speedtwin E2E Comet 1, which according to wikipedia is the only certified twin engine aeroplane approved for intentional spinning.

Can someone shed some light in the development and certification process with regards to spinning?
I wonder how a wing heavy aircraft can demonstrate the "normal" spinning requirement, much less the 6 turn spin requirement of an aerobatic aircraft.


Thomas

[Genghis the Engineer]

I wasn't involved, although I know the TP who flew that trial and have flown other spinning trials with the same chap so have a fair idea of his approach to things.

But what's the question - what do you see as being particularly different in regard of how you would explore and demonstrate the deliberate spinning characteristics of such an aeroplane?

G

[JOE-FBS]

Doesn't answer your question but this is an interesting NASA video of spinning a twin which I found recently when educating myself on the subject of spin testing in general:

https://www.youtube.com/watch?v=3cJkjk0hOU8

[CharlieJuliet]

According to some Pilot's Notes that I have, and my logbook, the Meteor T7 was cleared for spinning. This has the engines a fair way out on the wing. So presumably an aerobatic clearance was possible?

[Mach Jump]

So presumably an aerobatic clearance was possible?

You should check out the Meteor aerobatics of Janusz Zurakowski.

From Wikipedia:

At the 1951 Farnborough Airshow, Żurakowski demonstrated a new aerobatics manoeuvre, the "Zurabatic Cartwheel", in which he suspended the Gloster Meteor G-7-1 prototype he was flying, in a vertical cartwheel. "This jet manoeuvre was the first new aerobatic in 20 years."[6] The cartwheel used the dangerously asymmetric behaviour the Meteor had with one engine throttled back. The manoeuvre started with a vertical climb to 4,000 ft by which point the aircraft had slowed to only 80 mph. Cutting the power of one engine caused the Meteor to pivot. When the nose was pointing downwards, the second engine was throttled back and the aircraft continued to rotate through a further 360 degrees on momentum alone having lost nearly all vertical velocity.


MJ:ok:

[Genghis the Engineer]

This jet manoeuvre was the first new aerobatic in 20 years

I'm sure it was impressive, but given that not long before, the Porteous Loop was first shown, and for that matter there was considerable originality displayed between 1931-1951, that particular line is certainly nonsense.

G

[Mach Jump]

Well, it is Wikkipedia, so don't expect too much. ;)


MJ:ok:

[Mach Jump]

To return to the original question:

The increased moment of inertia due to the outboard mounting of the engines, and the increase in variables due to the possibility of assymetric power settings, may be compensated for, to a degree at least, by the much bigger fin and rudder fitted to a light twin to cope with the low speed assymetric flight case.

Aside from the need to explore more variations in power settings on entry and during the recovery, the consideratrions should be the same.


MJ:ok:

[goldfish85]

The Beech Duchess (BE-76) was put through an extensive spin program during its development. This was reported in an AIAA meeting in the early 1980s. The certification flight tests were more extensive than most single-engine airplane programs. Only 84 spins were reported which is not enough for intentional spinning. The airplane was not approved for intentional spins.

Goldfish85


Reference: RR Tumlinson, ML Holcombe, & VD Gregg, "Spin Research on a Twin Engine Aircraft," AIAA Paper 81-1667, August 1981