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STOL-X(perimental)


Martyn K
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Posted by Martyn K on 09/02/2015 10:46:43:

AUW - was less than 1.1kg Dry = 0.79kg Fuselage/Tail/Engine/radio gear and Flight battery and 0.25kg wing and flap and aileron servos. Not bad - a 25 sized model at 2.25lbs or thereabouts. I suspect that will be the main reason for the STO bit of STOL

Martyn

that's brilliant Martyn ,most of my thinking has been how to build light but strong for my STOL

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I managed to maiden the STOL yesterday afternoon. Conditions were favourable, 10kt SE wind blowing across the strip from the right, time 4:00pm (when flying), very dull and cool. Sadly, I was by myself so no photos or witnesses

Range Check - OK

Engine Run - OS26FS - running a little erratically, I wonder if it is over-propped with a 10x4? Fuel Contest10.

Anyway - model on the strip and opened it up, very slow to pick up to speed, but once rolling, the model tracked well on the strip on rudder control, a little right aileron needed as it lifted off and away it went. No problems so far.

A couple of circuits, basically - open the throttle and it climbs, close the throttle and it descends - very simple. Elevator throw seems OK, Ruder - although not large is surprisingly effective - flat rudder turns OK. Ailerons need some differential and a little less throw. Roll rate was very fast. Loops OK, tight as you want without being twitchy.

A little left Aileron needed for Straight and Level - Elevator trim was spot on.

The flaps were fun. I have 2 position flaps set - about 20 degrees and 60 degrees down as well as (obviously) no flap.

Setting the flap to position 1 caused a mild nose up - easily controlled on the elevator. Putting them fully down pointed the nose upwards at about 30 degrees but no sign of a stall. For mental comfort, I will mix in some down elevator with flaps fully down.

After about 7 or 8 minutes in the air I attempted a landing. Model on usual rectangular approach - although it was getting dull and my double vision problem was causing me a sighting problem, so my approach was a little high.

As the model went past me on approach at about 4m high, I simply dropped the engine back to tick over and it descended in an amazing 30 degree floating approach, settled on the grass at about 10kts and stopped dead. That was with the flaps up. I am really looking forward to trying again with flaps down, I think it will come down vertically.. I suspect that this model is very draggy which was why it was slow to get started in the first place.

There was no sign of a stall, never mind a tip stall, during this first attempt. I can see this is going to be a great Summer Evening flyer. What surprised me though is that despite its appearance, the model needs to be flown, it is definitely not a "hands off" aeroplane, so it is probably not the best trainer in the world. It is much easier to fly than the T240 though.

I decided to have a second attempt but in the process knocked the Tx aerial off my Taranis Replacement on order..

Next time, I'll try and get some photos or better, video..

Martyn

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I think it's time to get something right, pink is not allowed at SCRCS, I've got a very nice roll of opaque pink you can have if it is your favourite colour though smile.

You are going to have to call it "transparent red" and if challenged blame any pinkishness on exposure to long periods of sunshine. Admitting to having that colour by choice will be reported to the committee.

Oh and well done with the maiden.thumbs up

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Thanks all (and I told you the SCRCS members were a hard bunch)

Ian, Matt claims it is translucent purple. Obviously saw me coming and I didn't get any discount for that

Hi David

Turnigy MG-90S throughout. They seem fine for a model this lightly loaded but can be a bit noisy. I find the trick is to keep slop/backlash in linkages as minimal as possible.

Martyn

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  • 2 months later...

An update on this, I had flights 2-5 last night. A beautiful calm evening with a clear blue sky, ruined by a pink aeroplane clashing with the blue..

dscn1266.jpg

Since its one and only previous outing, I have guessed and mixed in extra down elevator to compensate for the severe pitching up when the flaps were deployed.

So.. last night, started the engine, model on the strip, 15 degree flaps selected opened the throttle and the model took off in about 20 feet in a nice gentle climb. Perfect..

Increasing the flaps to full (with additional mixed down elevator) and the STOL was still trimmed so really pleased with my guesswork on the amount of down elevator required.

What became entertaining was just how slow I could fly the model. At about 125 feet altitude, I simply slowed the model down- adding more and more up elevator until the models ground speed was almost zero. The wind speed was considerably less than 5knots at this time. However, when it stalled, it dropped a wing - usually because the ailerons had become totally ineffective and I was waggling like mad trying to keep the wings level. Nothing horrible though, just let the speed pick up slightly and it recovered immediately

However, I was not brave enough to try and land like that. Landings with flaps was so easy, drop the flaps, point at the strip and it lands - nothing easier - it is so slow - it probably wouldn't break if I got it very badly wrong.

One thing we did agree on is that the model suffers from adverse yaw due to drag on the down going aileron so I have now set some differential up so the down going aileron only travels half as far as the up going aileron - if that make sense. Need to retry it again.

Anyway, thanks to Andy Pace, one Camera Phone Shot of a flypast..

stol-ap1.jpg

Just what the psychiatrist ordered..

Martyn

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