Been a long time since I've posted on here but I've got an idea in my head that won't go away, no matter what I do to distract myself.
Is there any aerodynamic reason against putting contra rotating propellers on a piston engined single seated, twin boom fighter? I'm planning on using the Heller Saab J21 as the base

I can't think of any.

I am not aware of any aerodynamic reason or limitations, but noise and vibration would be the main problems.  Vibration likely due to complex flow coming off the front prop impacting the aft prop.  Make sure Sven has good ear protection under his helmet! 

I think it would look fantastic! 

Sud-Ouest (SNCASO) SO.8000 Narval


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"There was talk of a "J 21B" version in the postwar period, with a Rolls-Royce Griffon inline engine, a pressurized cockpit, and a bubble canopy, but of course interest in that timeframe had moved on to jet propulsion."
http://www.airvectors.net/avj21.html

Thanks for all the help and advice. I'd not heard about the Griffon engined version before and it sort of makes the contra prop seem not so whiffery now  still going to do it though!

Always liked the look of the Narval 

No reason not to do it at all! On the contrary - it would be absolutely awesome to see this realised in plastic.

As for the IRL development of Swedish SAAB fighterbombers, the propdriven A21A entered sqn service in 1946, but already five years later, the A21R, i.e. the Goblin powered jet derivative, took its placve. Then things happened fast. In 1954, the A29B Tunnan (flying barrel), and in 1956 the A32A Lansen (Lance). All these premiered on the same wing, the 7th in western Sweden.

Looking at the above timeline, don't you think an evolved up-powered and contraprop version called A21B or C could have been almost mandatory around 1948? There seems to be a gap..

Based on the same idea (well sort of..) I did the Martin Baker MB.7: https://www.whatifmodellers.com/index.php?topic=48780.msg908301#msg908301

IMG_7192 by Buddy Holly, on Flickr

I'd say: Go for it!
David aka 63cpe

  

Quote from: Muddyboots on November 01, 2022, 03:10:54 PMThanks for all the help and advice. I'd not heard about the Griffon engined version before and it sort of makes the contra prop seem not so whiffery now  still going to do it though!

Absolutely! The Griffon J-21 was just an idea. Great minds think alike.... Nothing ever came out of it back then. About time to do something about it.

Quote from: jcf on November 01, 2022, 11:01:24 AMSud-Ouest (SNCASO) SO.8000 Narval


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I've got the Akatombo Works 1/72 resin kit of this in the stash --- 

It looks like it'll be a nose job on a mk19 spitfire bolted to the back end of the Saab then. Swedish splinter cam seems to be in order here 🤔

Splinter camo would be cool.
It might not be correct for the period when a Griffon J-21 would have operated "In Real World". Which might or might not matter.