TOPIC: Yak 23 & Jet Spifire

Hi guys,
I'm not sure where this thread will be going (hopefully, eventually to a 'flying thread) but I I thought it interesting to discuss Roger Reese's own design Yak 23 for TSPL-1/TSP L-2.
So, to begin, below is one of the first pictures Roj sent me, asking for advice on motors and trimming:



Roger’s Yak 23, originally for TSP L-1. Roger, a modeller after my own heart, builds ‘on the fly’, so enabling others to realise his unique design will take some effort! The fuselage is extensively sheeted) and the motor is enclosed in a pod. True to his team race credentials, Roger has (a) included a race number (though this is authentic) and (b) put a life-like pilot in the cockpit.

More photos followed our initial discussions:







As you can see, this is unique and a ‘proper’ built up model, with more than a few interesting discussion features .Note that the motor pod. This is very brave of Roj, I thought, though ... wait a minute .... the only other similar model I knew of, a Yak 15, also had, I think, its L-2 mounted in a pod.



To confirm this I needed to find the plan!

Below is the plan of this model:



The L-2 motor appears to be not completely shrouded, but mounted in a trough




Above: example formers from the Yak 15 plan. Note the trough for the motor.

Burying a motor is not a good thing for motor efficiency!. Perhaps the mounting of the motor in Roger's Yak 23 needs some thinking about ...

Meanwhile, some info about the full size Yak 23.

The Yak 23 is a derivative of the yak 15 which was itself derived from the Yak 3:



It's an interestng, if crude early post WW II soviet jet fighter , widely exported within the Eastern bloc.

Back to the model ....

I asked Roger for a copy of his plan. "What plan?" he said. He then drew up the rather nice rendition below:



I thought the admirable Rob Smith could wave has magic CAD wand over this. Which he duly did:



Note the motor is now 'external', hanging in the breeze'. More practicable , if less aesthetically pleasing. Note also the horizontal crutch, a good feature and facilitates easy alignment and fixing of a 'one piece' wing.

Rob's plan is for a model about 10% larger than Roger's prototype, and Roger (or anyone else who fancies one - please ask me for a copy of the plan) hopes to build a second prototype from the plan and promises to 'add lightness'!
If this model is succesful, we can then think about a shrouded motor and an open air intake.

More later .....

As promised, below is what Rob, Roj and I have been up to. Rob was, of course the main driving force - I'm merely the recorder - but it wouldn't have happened without Roj's Yak 23.

First, Rob noted that the Yak 15 and later Yak 23 were derived from the Yak 3:



1, the Yak 3. 2, yak 15. Hmm thought Rob, if they can do that with the Yak 3, why couldn't Supermarine have done something with the Spitfire (3 & 4)?

Such an aeroplane, we thought, would have been a lot easier to produce and have better handling characteristics (and a higher Mach limiting number) than the wretched Attacker.
Below is what Rob came up with:



And, ever industrious as he is, soon had a model made. As is Rob's methodology these days, it is of printed paper over balsa construction:







Rob sent me the model so I could add the TSP L-2 motor mount and balance it in the correct place (33% back from the root chord). It needed a little over 5 g. The model is the size of one of the old Veron Jetex models (have a look at Phil Smith's venerable Attacker):



Above: Supermarine's egrigious Attacker was derived from the Spiteful. They would have done much better with a Spitfire T 30!

Rob's Spitfire T 30 'might have been' is 16" span", and weighs 41 g - just right for a TSP L-2HP.

Both the Yak 23 and Jet Spit are as yet unflown Roj brought the Yak 23 to the last Old Warden meeting, but it was much too wet and windy to do any flying at all. and the Spit T 30 is only just finished.

Perhaps we will have some nice calm weather at Peterboro Flying Aces. I do hope so. It's on Sept second ..... to our prayers!

Cool, it still looks very much like a Spitfire.
Not sure about the motor angle though, it looks like up thrust as the motor is aligned with the wing underside. I would lower the front of the motor a bit at the very least.
Roger comments:
good point. In mitigation can I explain the motor mount was only 'tack-glued on for the photo session?
I'll align the motor properly and add a thin metal thrust-tab before flight trials.

Very nice work there, guys!

It's an interesting thought. A Spitfire with a jet tacked on.
Great work on the aeromodelling front too!!