Magnum 40, strange wing profile.

[Dad_flyer]

I spend (far too much) time wandering through Outerzone. I came across the Magnum 40 (and 60 and 64 cycle)

https://outerzone.co.uk/plan_details.asp?ID=6790

https://outerzone.co.uk/plan_details.asp?ID=10492

and

https://outerzone.co.uk/plan_details.asp?ID=11425

It has what I can only describe as a symmetrical reverse cambered wing section.

 

Can anybody shed light on this? Was it supposed to give particular flight characteristics? Or is it another place where at our scale the wing profile does not make so much difference on a sport model?

 

[Robin Colbourne]

Many years ago Chris Foss gave a lecture to our club about his company and models.  He mentioned how some of his power designs had a slightly concave profile behind the spar to increase the effectiveness of the ailerons.  With a more conventional symmetrical section the aileron could be in dead air until significant deflection was made.  The section shown appears to be a far more extreme version of what Chris described.

Edited May 27, 2021 by Robin Colbourne
punctuation

[Frank Skilbeck]

The Tempus was quite popular at our club a few years back and had a similar wing profile, I never had one but they did seem to fly well.

[Dad_flyer]

Thank you Frank. Not much information available on the Tempus, but it does mention "the unusual wing profile".

[kc]

It certainly is a strange wing profile.   I note that it dates back to 1978 and that since then the designer Don Santich has had other plans published - notably the various Hots designs and they don't have this wing type.  So maybe it doesn't offer any advantage to make the slightly more difficult construction and covering worthwhile.   

[Dad_flyer]

I think that is telling kc. Also if Chris Foss talked about something similar but does not incorporate it now, and the fact that the collective wisdom of the forum has little memory of it.

 

Something that seemed like a good idea at the time then.