TOPIC: Yak 23 & Jet Spifire

Roj has been busy building a Yak 23 Mk 2. This is 10% bigger than the Mk 1. Progress so far:



Roj writes, " Fuz nearly there, just nose ring and infill for canopy. Wings next
I am sanding in 'lightness' and combined the fuz and fin. It currently weighs 10g". Which is pretty good I say!
Trying for a bit less.

Very nice Fuse.

Old Warden yesterday was a meet up with fellow rocketeers.
Weather OK, but too windy for my lighter/smaller models with only my Malmstrom 'JetStream' flying anywhere decently.
Good news tho. The Yak 23 during a lull in the gusty conditions proved a good flat glide. Promising?
The proof of plan Yak at +10% has progressed to tissue covering and UAW a healthy 27gms.



Above: considering the conditions, the Skystreak, an old Ray Malmstrom design for Atom 35/Jetex 50, went well with a TSP L-1.

I got to take a look at Roj's YAK 23 at Old Warden on Saturday and upon re-reading this thread remembered that I had prevoiusly considered models of aircraft that where essentially piston engined aircraft fitted with under slung jet engines.

In March 1943 Focke Wulf considered a Junkers Jumo 004B engined design which used the wing, tailplane, rear fuselage and undercarriage components from a Focke Wulf 190A. The jet engine was to be fitted beneath the wing forward of the trailing edge, but this lead to the rejection of the design known as the P1 (Plan 1) for the fear that exhaust gases could damage the rear fuselage, sounds familiar.

I built a profile model as shown below believing that the layout may give me an extended glide phase but was not as succesfull as I had hoped due to to the fuselage being on the heavy side with a bend induced by laminating some carbon fibre tows into the fuselage which also made it impossible to straighten.




Another design that peaked my interest was the suggestion that in a step towards the F-84, Republic looked at fitting a J-35 engine into a P-47 Thunderbolt. Not sure if this was real or otherwise as all I found on line was reference to a 'Sharkit' resin set required for conversion of an Hasegawa plastic model kit.

It was enough for me to start drawing up a model, below you can see how far I got before interest moved to other things. Perhaps its something I should revisit again?

Roj has just sent me photos of progress with his Yak 23 mk2 which I've assembled into a montage:



Roj writes:

"I've sprayed the Yak [an authentic Soviet muted silver, it's a bit scruffy (esaki tissue sanded thru) to be honest, but it was a rushed build. With the motor pod, but less motor, it weighs a creditable 34 gms. I'm going to hide bad workmanship with panel lines and Russian decals.
A test glide in the garden was very promising but the amount of nose weight required was dissappointing. In hindsight the whole front of the fuz could have been infilled with balsa as I have had to use ballast. A heavy [ish] thrust tab might help and I hope it will fly well under power".
I commented it's not too late to add sheet infill to the nose as it's always a good wrinkle and means less damage to the nose on a hard arrival!

Here are the latest photos from the ever industrious Roj Reese:



Roj writes:

'I chickened out with marking up panel lines as the Esaki tissue too sensitive and Wing insignia too small. I think may cut a mask and spray over waterslides.'

Well, it looks pretty good to me!