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Speed Twin ST2 - a twin-engined kit build


Tim Hooper
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Gentlemen,

Sadly I have to report the demise of my own much-flown ST2. sad

Having flown the pants off it last weekend at the Greenacres fly-in, I was on my landing circuit base leg and preparing to turn onto final approach at about 30 feet altitude, when the model barrel-rolled inverted and dived into the ground. The damage was beyond repair, I'm afraid.

Initially I thought that an aileron servo had locked over, but the post mortem showed everything to be working as normal radio-wise.

So, given the unhurried (but irrevocable) way it rolled over, and the length of the preceding demo flight, I'm thinking that what happened is that the battery voltage dropped to the point that just one of the ESCs reached the point of LVC and so the left motor stopped for a second or two - perhaps just long enough to have fatal consequences.

Oh well. Perhaps in the future I'll build another - this time with retracts and a moulded canopy - maybe enlarged to around 60" span. But not yet, eh?

tim

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Tim, sad news thatcrying, in regards to a retracts on a bigger ST, I enlarged my ST by 20%, and fitted small H/King electric ones, which fold up forward. I repostioned the mount further aft and increased the "rake" so as to balance the aircraft on the ground and completly hide the wheels when folded, albeit small wheels are necassary ( 2" ) but it looks very impressive in the air. I set the c/g with the wheels down, so when they are up, it becomes slightly nose heavy.....works wellthumbs up

good wishes

Barry

 

Edited By A.A. Barry on 02/06/2013 01:17:03

Edited By A.A. Barry on 02/06/2013 01:17:43

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  • 4 weeks later...

Finally, SpeedTwin is no longer nude. I ended up painting her in homage to the original but not exactly the same. It was a nice day so I used water based enamel paint which was ready for a second coat in 15 minutes. Tim's decal set (ModelMarkings.com) really brought her to life.

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I was sorry to hear of Tim Hoopers loss! Perhaps this one will live as long and fly as hard.

Colin

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Colin,

Your ST looks magnificent! I'm so glad that you're pleased with it and, as you say, I hope it has a long and happy career!smile d

Funnily enough, I had a chat with the management at last weekend's RCM+E fly-in, and the view was that they'd be extremely interested in a scaled-up ST - complete with clear canopy and retracts - so that may be one for the future perhaps.

tim

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  • 3 weeks later...

Hi Tim,

So sorry to hear of the demise of the prototype. I'm happy to report that mine's still unmarked and flying well, mind you I'm a fairly conservative pilot - just loops, rolls, reversals and similar. She looks good on a low pass (not inverted, I'm not up for that) and still sounds wonderful.

There would be a great temptation to build a bigger version, especially with retracts and winglets. You've done a lot to advertise the ST2 for the manufacturers, perhaps they'd come across with some decent drawings so that you could make the next one true scale. Then I'd definitely be interested.

Regards, Rex

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Thanks for the comments Gents! It's great to know that the ST2 has gained something approaching a following!

My build schedule is full for the time being, it has to be said, but I'm certainly not ruling out a 60" version in the future.

Mind you, if either of you two were to do the deed and draw up the enlarged version, then I'm sure that management wouldn't mind - especially if you were to make a fully-fledged submission for the mag on the way....

tim

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Tim, Ah, well then, if I just e\nlarge your design, with a few mods.who can say it's not accurate, ummm interesting, I feel the nacelles could do with a bit of triming down, you have already mentioned the balance tabs on the stabilizer and a slightly different wing profile. should do the job, any other changes you think off??

Rex your input, or anyone else enlightened

Barry

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Barry,

Tim's representation was pretty good given the lack of assistance from the factory, and it certainly resulted in a nice looking model which compares well with a photograph and garners a lot of favourable comment, but you notice odd little things once you've completed a build and start to look at your own work critically.

For me there are two areas that stand out. The fuselage forward of the cockpit is actually square in section (with rounded corners) so the nose is quite flat on top, and the nacelles are quite different. Getting the nacelles right is going to be quite a trick, as the damn things look different in every photo I see, but they are definitely a lot squarer in section than Tim's below the wing, and a lot more shapely above the wing.

To be honest I feel a bit cheeky criticising Tim's effort as he produced a beautiful plan and I did enjoy building it, but if I built another those are the areas I would do differently. I built my model with fixed u/c because that's what the full size aircraft had but I'd fit retracts and winglets now that I've seen how good that looks. Like most people I have three future projects in mind but I'd like to build a bigger Speedtwin because it attracts so much attention and is lovely to fly - I'm not really up to submitting anything for publication though so go to it Barry.

Rex

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Rex,I'm sure you noticed, as Tim did also, that the earlier prod. model ( full size) had inverted inline engines , they could be gypsy major, it doesn't look as apealing, but that could be an option.

Yes Tim did a wonderful job on the ST, I feel humble even trying and match his build, but those nacelles where a handful, maybe the bigger version would be easer....... maybe...maybe

Barry

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Get to it, lads! teeth 2

I've never pretended to be a real-scale modeller - as long as the model looks sort of right in the air, then I'm happy.

So those nacelles are my best guess and, yes, they've been revised and changed since the aeroplane first flew. I'm willing to be thtta they've been changed again since the retracts have been fitted too!

tim

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Hi Tim and Barry,

For an aircraft that has been around since at least 2001, is far and away the most aerobatic twin,and which created a lot of excitement at Farnborough last year, there is remarkably little information readily available on the Speedtwin.

The nacelles keep changing because the original ST1 (G-GPST) built by Peter Philips, had Continental 0-200 flat 4 cylinder engines producing 100 hp. The second version ST2 (G-STDL) which is "our" model built by Speedtwin Developments started life with Walter M332B inline 4 engines producing 160 hp and the current version has an unknown (to me) flat ? engine producing 205 hp. There was also a wing redesign at some stage, probably related to the doubling of power and huge increase in speed. None of this is definitive, just what I've found on the internet.

The Walter engined version had a lucky escape following a prop failure in 2009 which may, and I'm guessing, have prompted the change to the current engine. For those that are interested here is a link to the investigation and attached report: Air Accidents Investigation: Speedtwin ST2, G-STDL. This is moving away from the modelling world, but as I spent some years crack checking propellers at overhaul it's right up my alley.

I'm sure you are correct Tim, about the nacelles changing again - they'd have to for the retract mechanism, but as the photo you featured on page 14 is the only one I can find of the retract/winglet version, there is no way to judge. It seems surprising that Speedtwin Developments won't come across with a bit more gen, I thought they would be interested in what you have achieved and get right behind you.

Rex

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Guys, I am leaning towards this varient, (above pic) mainly to keep the nacelle building easier, it could also accomadate I.C engines as well, but with retracts included, folding forwards.It is a little different than Tims varient, but I will use Tim's plan as a base

What do think Tim, Rex and RCME bosses

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well, I have dug up the orginal plan, so I can get started with this build,first i will enlarge thethe plan by 25% that brings is out to 60" or close to, as I have a A3 printer, that shouldnt be too much of an issue.

the nacelle design will be the starting point and designing the internals of it. so wish me well

Barry

i

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