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Speed Twin ST2 - a twin-engined kit build


Tim Hooper
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It's done!

Let's have a look at a few details first though.....

The twin ESC's live on top of the wing.

I had to cut out a portion of nacelle, screw in the UC and then replace the balsa.

The aileron servos are secured to the inside of their hatches with double-sided tape, abetted with a cable tie.

Once again, Tim Calvert at ModelMarkings
has done a magnificent job with the graphics!

The 3S 2700 pack sits on a sloping tray in the nose.

The tail servos are mounted in the tail. Funny, that.

tim

Edited By Tim Hooper on 28/04/2012 20:45:08

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So before we see the completed model, here're a few specs;

Span - 45"

AUW - 49oz

Power - 370 watts

Wing loading - 20 oz ft

Power loading - 119 watts/lb

Looks sort of promising, yes?

Edited By Tim Hooper on 28/04/2012 20:45:59

Edited By Steve Hargreaves - Moderator on 29/04/2012 17:23:47

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Tim just a thought, may I suggest you try contra rotating props? Assuming you can get a puller and a pusher the right size (I think 7x5's are available) then contra rotating removes all torque effect making a twin track beautifully even if you open the taps quite roughly devil

Rotating "in at the top" seems to be the way to go, then if one motor does fail, the torque effect from the other is in opposition to other effects, which helps.

Waiting with bated breath to see how she goes.. bet it won't be today!
Cheers
Chris

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Thanks guys! It's great to read such a favourable reaction!

Chris, I did consider counter-rotating props as you suggest. However as I'm hoping that this model will be published I'm pre-guessing that most potential builders will use readily available hardware (ie., normally-formatted props), so I want to prove it flies in that configuration first. I won't be a big deal to remove the packing washers from behind the motor lugs to get rid of the side thrust if I do decide to alter the rotation of one of the motors later on.

Roger, if it flies successfully, then I'll submit it for consideration by the editorial staff.

timsmile d

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Well.......

It flies!!!!!

.....and as forecast by young Mister Fenton, it's certainly no slouch either. wink 2

The rain stopped long enough for us to head to the field. Range checked OK. I handed Netty the long Sigma lens and asked her to do her best in the dull and drear conditions - and so she did!

Here's the take off, followed by the climbout out.

It was immediately apparent that the model was pitching up sharply as the power was increased, so for the duration of this flght I wound in a lump of down trim.

Having established that the ST was airworthy it seemed a shame not to give it the beans a bit, so we looped, we rolled (very sharp on the ailerons BTW), we flew inverted, did a couple of Cuban 8's, then throttled back to test the slow speed handling. No probs. A couple of slow circuits followed by a gentle landing. Excellent!

Back home I've added a couple of degrees downthrust to the motors, so we'll see what happens next time. All in though, it bodes very well!

timteeth 2

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yes Well Tim you have done it again what a bute twin and just when i was looking for a twin to put two OS 202st that were my late fathers and never been run

having just cleared the work bench of the "Cleen Sweep" and winter approaching fast this could be my next project

I will now read this build blog and see what i am up for LOL

Ray from DOWN UNDER

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