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Design & Build Junkers F.13


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  • 2 weeks later...

Hi All,

I have weighed the model in it's flying condition and double-checked the position of the CoG, I don't want a repeat of my FW200 Condor. The CoG came out at 70.5mm from the leading edge which is just about 1/4 root cord.

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So the all up weight is 5 3/4;bs or 2.6kg giving a wing loading of 24.6 oz/sqft

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Altering the static margin by 5% either side of 10% move the CoG

So with a static margin of 5% moves the CoG back to 83mm from the leading edge

And with the static margin increased to 15% the CoG moves forward to 64mm

I will balance the model at 70mm as a starting point for th emaiden flight, which will not be for a while, I went flying today and our patch is very waterlogged and has been cut up by an off-road motorcycle/s which made take off and landing a challenge.

That's all for now

Regards

Robert

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  • 1 year later...

Hi All,

Today was the day that I maidened the Junkers.

Here's how it went.

All the control movements were guesstimated and having a Spektrum radio I had three rates available to me so I set them up as low medium and high.

The engine had not run for a couple of years and was fired up almost straight away with no adjustments needed with plenty of power, range checked so all looking good. Being an unusual model it gained a lot of interest from my fellow club mates, I handed my camera over to our chairman for some flying shots.

 

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So off onto the newly mowed strip, weather conditions were good sunny skies light wind.

Take off no1. nosed over after around two feet, wheel went into a rut. The u/c may be a little too far back, as soon as the tail gets above level she will start to nose over without power. so back to the pits to restart and try again.

 

Take off no 2. she flies but OMG, the rates were all on low and the ailerons were not effective and not enough speed and she ended up in the rough very ungraceful

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One of the advantages of band on wings that plus a low speed arrival. On checking over the model and all seemed well with no apparent damage done.

 

Take off no3. After a short break the model was lined up again and this time I had all the rates set to high. Take off was fairly short having to keep up elevator to try to stop her nosing over but as soon as she was in the air I backed off well she was a real handful needing a lot of aileron trim and flicking the elevator trim to medium

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Whilst I was trying to trim out Ian got taking some flying shotsDSC00311.thumb.JPG.d443438098f529f773fd5373677b1fa8.JPG

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The colour scheme looks good in the air

It was shortly after this photo was taken that disaster struck with the right wing coming off leaving the aircraft crippled and uncontrollable all I could do was to close the throttle and collect the pieces. 

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On bringing back to the pits and on examination the dihedral brace had sheered, damaged undoubtedly by the previous arrival. Note to self use thicker ply for braces.

So that is it the end of another model, at least the engine is ok and I have salvaged all of the electrics for another model.

 

That's all for now

Regards

Robert

 

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