Aerobatic and not cleared for spinning??

[Confabulous]

Guys,

The Glasair IIS RG is cleared for aerobatics (rolls (not snap rolls), loops and Cuban 8s) in the US, but it's not cleared to spin. In the UK it's not cleared for aerobatics at all (although I'm sure they've been rolled when no-one's looking).

So, why clear it for aerobatics if it's not cleared to spin? Surely running out of energy at the top of a loop can lead to a spin? So can a hammerhead, Immelmann, etc... I just don't get it this at all. Any ideas how this came to be? Or am I getting in a bit of a spin? Tying myself in loops? :}

Note: I'm thinking of building one of these masterpieces, so I'm not trying to call its capabilities into question! I think the PFA's attitude is intelligent - if one aspect of its aerobatic abilities is called into question, then it shouldn't be aerobatted - at least not by low-hour pilots like me.

Conf

[Shaggy Sheep Driver]

That doesn't make sense. A botched aerobatic manouvre will result in either a spin (could be one of many types of spin) or a spiral dive, so before commencing aeros you need to be sure you can recover from both.

SSD

[DB6]

Might be in the wording - maybe not cleared for intentional spinning but who knows how the Yank mind works on such matters :eek: .

[MLS-12D]

The concept of an aerobatic-but-not-spinnable airplane doesn't make much sense to me, either. But there are precedents: e.g., the Globe Swift is (or at least was) cleared for light aerobatics, including flick rolls, but not spins (reportedly because the latter had a tendency to go flat after a couple of turns).

The factory website (http://www.newglasair.com/glasairSIIspecs.html) is not very informative; it mentions "unrivalled aerobatic capability" but doesn't say what specific maneuvers are approved (or prohibited). It says that "All Glasairs are fully aerobatic: +9/-6 G Ultimate Loads!" (http://www.newglasair.com/designglasair.html), which is somewhat misleading (perhaps dangerously so, as it invites the unwary to push the aircraft beyond the +6/-4 G flight envelope that it is stressed for).

[Confabulous]

So I'm not alone in thinking this! Actually I've been looking around, and the Questair Venture (http://www.nuventureaircraft.com/specifications.htm) seems... interesting. Fast, long legs and built for two. It's a sawn-off Malibu.

Challenge: Could I build the a/c here (Ireland) and put it on the N-reg? It's not PFA approved and I doubt it would be since the performance is so good.

Conf

[MikeJ]

For Glasairs, the situation is straightforward.
The POH states clearly that it was designed as a sport aerobatic aircraft, including steady inverted flight if the optional flop flop tube is fitted in the aux fuel tank, and the specified inverted oil sytem is used for the Lyc. engines.
This does not apply when the optional wing tip extensions are fitted, which greatly reduce roll rate, and are not stressed for aeros.

Some, particularly Glasair IIIs, have been used for delightful professional displays in the US.

In an early Glasair News, there was a long article on spin testing by a skilled aerobatic pilot. The essence of which was
(a) very difficult to get into a spin using normal tequniques. It would drop into a spiral, but having found a technique
(b) normal recovery worked quickly, but was easy to push the stick too far forward, and they recommended full opposite rudder and letting the stick go!

Glasair have made it clear that the reason that they prohibit intentional spins is the US comensation environment. Commercially, they were not prepared to spin test an envelope of possible assembly errors by amateur kit builders. Eg, who knows the effect on spin recovery of someone locating the tailplane 1/2" either forwards or aft of that specified, which would be unnoticed in normal flight.

Several years ago, someone was trying to get CAA approval for aeros for a GIII, all of which are on CAA permit, being outside the remit of the PFA. I do not know if that was successful.

Mike.

[Confabulous]

Mike,

Thanks for that, it explains a lot! :cool:

Conf

[Brooklands]

Confabulous,
Challenge: Could I build the a/c here (Ireland) and put it on the N-reg? It's not PFA approved and I doubt it would be since the performance is so good.
No, I don't think you can. IIRC Aircraft registered in the FAA Experimental category can only operate outside the USA for limited periods of time (one month?), and then only with the permission of the regulatory authority of the country they are operating in. I've a feeling it was discussed either here or on the Flyer forums not that long ago - try a search on 'experimental' and FAA

I'm afraid if you want to build your own plane, then the route of least grief is a 'PFA approved' model, with as few modifications as possible, Vans aircraft (http://www.vansaircraft.com)
seem to have a strong following and there's an active e-mail group (http://groups.yahoo.com/group/rvsqn/) in the UK

Brooklands

[Confabulous]

Strange as it seems, I'm not hugely interested in having an aerobatic a/c. I just think that the Vans have gone as far as they can in terms of all-metal a/c and the Glasair represents the future - although there's little doubt Vans will go composite too. According to this (http://www.oriontechnologies.net/Documents/Airfoil.htm) article, the Glasair suffers because the aerofoil it uses is too draggy at high speed.

That said, the Questair Venture is beyond fast (250kts at sea level) and aluminium to boot. I read somewhere (I think it was Flyer, the one that had the TwinStar Flight test) that a Velocity was built in the US, certified and ferried to the UK and it's a homebuilt.

Come to think of it, the TwinStar's performance is only average when you compare it with the new homebuilds... makes me wonder.

Conf

[cubflyer]

Not sure that the Glasiar is the "future" as you say. Its been around for years! Id guess about the same time as the RV-6. But it is faster than the RV-6/7, although less room and less baggage space. But Ive only been in a Glasair II. The III might be better.
But also a lot more expensive. I wouldnt bother with the Questair Venture, very few seemed to get built, dont think they sell kits any more, it was Fast though!
If you want a really fast aircraft then look at the Akland Legend, or Team Rocket F1 Rocket, both outside the PFA's approval though.
Not sure how those guys manage to operate the N reg velocity over here. BUt one of them may have US citizenship, which would cetainly help. Operating N reg experimental aircraft outside the US is certainly not encouranged by the FAA and must be difficult, otherwise everyone would be doing it. There are very few N reg experimental aircraft in Europe and most of those that are here are owned by US citizens.

PS Another aircraft approved for Aerobatics and not spinning (in the UK anyway) is the Harvard/T-6

[Structural Failure]

The Corby Starlet is another one that is cleared for aerobatics but not spinning. When it was designed in the 60's the tested it thoroughly and it displays unconventional spin habits. However, with the Australian "Experimental" catagory i can spin test it mysely and have mine approved to be spun. You guys need experimental!

SF

[djpil]

I understand, from second-hand info, that the Starlet's spin characteristics are:
- recoverable.
- spin becomes more like a flick, very oscillatory.

Are you really going to spin test it yourself and get it approved? Don't take this as encouragement to do something bold, but if I had a Starlet myself, I'd want to modify it to fix those spin characteristics.

I belive that the Pazmany Pl-2 is also approved for aerobatics (not sure whether it is so in Australia) but it has an unrecoverable spin after about three turns.

[Lowtimer]

"Aerobatic but not approved for intentional spins" seems to be quite a common category amongst warbirds, and if you look in the WW2 pilot's notes you'll see that laid out for quite a few of the fighters in RAF service. Always struck me as odd, too, but there you are.

[MLS-12D]

Strange as it seems, I'm not hugely interested in having an aerobatic a/c.Yes, it does seem very strange. :confused:

the Glasair represents the future Not my future! :hmm:

[kluge]

I believe that the issue of aerobatics ok but not cleared for spins is due to a number of issues such as:
- non standard spin recovery techniques
- a/c stability and ability to recover at various stages of spin, incipient or fully developed
- engine stopping during spin necessitating air starts (eg Robin 2160s - good fun when this happens)
- spin stability characteristics depending on CofG position and different weight loadings

It is not really a function of 'g'. There is very little loading on an airframe when spinning (typically 1g). Flying normal aerobatics within acceptable airframe tolerances and not inducing 'rolling g' etc is part of the 'utility' category for which that aircraft is certified. Certainly bodging a manouvre potentially causing a spin (eg screwing up a hammerhead or an immelman) from which a spin could be unrecoverable under normal conditions would prevent me from trying it - or maybe they just never tested all aspects of spinning properly - I think this is the case with the RV7 if you dig into their website.

K