Engine Position

Yabby Fri Jun 25, 2021 5:57 am

I like building and flying half-A profile slab wing models with my Cox Surestart engines. I build from plans I find on outerzone and I also design and build my own models to see how they go. I have noticed looking at plans for slab wing half-a profile models on outerzone some have the propeller center-line quite a bit above the wing center-line and others have the propeller center-line inline with the wing centre-line. The half-A Nobler has the propeller center-line quite a bit above the wing center-line and it is my understanding it is quite a good model for a slab wing profile plane.

Is there a significant difference in the way a model will perform dependent on the alignment of the propeller center-line in respect to the wing center-line? I am not technically astute in this area and a basic "high level" understanding of the difference in the engine mount position in respect to the wing may help me with my own designs for half-A models.

Any thoughts, opinions or information greatly appreciated.

Yabby

batjac Fri Jun 25, 2021 4:49 pm

Not really. For larger, Hi-Zoot planes it makes a difference if you're going to fly competition, but if you're just flying for fun it isn't a big deal. All we really need for our 1/2A's for sport flying is to ensure is that the wing and tail surfaces are parallel with each other and that the engine thrust line is also parallel with the wing.

Some 1/2A designs have some "up" built into the stabilizer, but those seem to be planes designed as basic trainers just to keep the novice in level flight with low powered engines. At least that's how I interpret it.

The Level-Headed Mark

Yabby Fri Jun 25, 2021 5:33 pm

Lol. Thanks Mark, I like that answer as that is how I built planes as a youngster and have been doing again because it seemed easy and I sort of thought symmetrical with centers aligned had to be a sort of reasonable average. And as Im sure I have said many times, I dont compete, never will, but dont quite fly just roundy roundy, It try and do stuff and am learning and having lots of fun, both building and flying my simple models. :-) Thought it was worth asking though, as there is a real lot I dont know, and sometime simple changes can make a big difference.

Thanks for the reply.

Yabby

rsv1cox Fri Jun 25, 2021 6:55 pm

Yabby wrote:Lol. Thanks Mark, I like that answer as that is how I built planes as a youngster and have been doing again because it seemed easy and I sort of thought symmetrical with centers aligned had to be a sort of reasonable average. And as Im sure I have said many times, I dont compete, never will, but dont quite fly just roundy roundy, It try and do stuff and am learning and having lots of fun, both building and flying my simple models. :-) Thought it was worth asking though, as there is a real lot I dont know, and sometime simple changes can make a big difference.

Thanks for the reply.

Yabby

I have thought about that too. Seems to be a function of style and design.

A Cox .049 powered crawdad/fish. Interesting..............