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Petrel vs Minimoa

Anything to do with gliders & gliding.
Jolly Roger
Posts: 573
Joined: 30 May 2015, 20:35
Location: Sutton Bank, North Yorkshire

Petrel vs Minimoa

Post by Jolly Roger »

These are my two fave vintage gliders, but I always wondered which would out climb the other.

On the one hand, the Mini arguably had more advanced aerodynamics than the Rhonadler-based Petrel. On the other hand, anything made in Yorkshire must be better :D

Anyway, here they are flying together last year, and I suspect the result is ...well... Sorry Fred.

Attachments
petrel vs mini.PNG
Bill_E
Posts: 9
Joined: 30 Aug 2021, 15:33
Location: Child Okeford, Dorset

Re: Petrel vs Minimoa

Post by Bill_E »

Lovely piece of film of two beautiful sailplanes. Of course the pilot of the Petrel may just have not found the best lift?

Thanks for posting.
Bill
Jolly Roger
Posts: 573
Joined: 30 May 2015, 20:35
Location: Sutton Bank, North Yorkshire

Re: Petrel vs Minimoa

Post by Jolly Roger »

Bill_E wrote: 04 Jan 2022, 10:03 Lovely piece of film of two beautiful sailplanes. Of course the pilot of the Petrel may just have not found the best lift?
Good point Bill - there are so many variables that you’d need many tests over a long period to isolate the performance of the aircraft.

There’s also the question of what we mean by performance - is it to climb fastest in weak lift or travel furthest and fastest.

Last Summer I stopped mowing the lawn to watch the old K8 from the Yorkshire Gliding Club join a Ventus, Discus and DG1000 already circling in a thermal above our cliff. It placed one wingtip daintily into the heart of the thermal, then circled slowly and stately around the core, whilst the heavier, slippier white gliders skittered around the outside, struggling to claw into the stronger lift. Maybe 10 mins later the K8 emerged top of the pile. The glass gliders then slid off on some distant cross country, in fast, shallow glides, leaving the K8 pilot to stooge up and down the ridge, probably sipping tea from his/her thermos.

I love watching both types of glider. The kinetic energy of the glass gliders is thrilling, but the colourful vintage stuff is equally entertaining for the way they hang in the air, sometimes pegged into the sky if the wind is strong enough.

Rog
Paul_Williams
Posts: 173
Joined: 18 Mar 2015, 17:53

Re: Petrel vs Minimoa

Post by Paul_Williams »

The Rhonadler/Petrel wing was designed before the Minimoa and has extreme undercamber. That rather limits the speed range before drag seriously degrades the glide angle. Whilst the Minimoa has the better straight line glide, I suspect the Rhonadler/Petrel will circle slower/tighter in the thermal core and therefore climb faster. Another factor here, is control response. Jan Scott told me that his Minimoa had very ineffective ailerons - mind you it had a hell of a lot of filler to smooth out the ply which had sagged inbetween the ribs. He did a fast fly by at an airshow , went to waggle the wings at the crowd but banging the stick quickly side to side had little effect. So poor ailerons and excessive gull, probably makes it harder to centre the Minimoa in a thermal as quickly and as effectively as other types..... for the average pilot.

Many considered that the success of the unremarkable Ka.6 was partly down to easy handling.

As for the Ka.8, I rather lost sight of my club on a hazy day and get uncomfortably low, when I saw a flash of wings. Managed to reach the glider and joined the thermal, to find myself in a pack of more than a dozen gliders in a regional competition cross country. I was easily able to out turn and outclimb all of them, until the pack departed. Very confidence building, although I have a vivid memory of the wing of a 22m Kestrel passing me in the corner of my vision, like a giant sharks fin !
Paul
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