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Construction Details. The following assumes that you have built several SPAD's and are familiar with their construction. This model started with a wing and was figured out from there, TLAR (That Looks About Right) they call it on the SPADWORLD forum, and that's a pretty good way of describing how it came together.

First flights with twin OS 25 FP's

 This plane has a fairly high wing loading, even with .25's it is around 22oz a square ft. After we had got both engines running reasonably I tried some taxiing around the strip, steering is good, even with a non steer able nose leg, but if turns where made to sharply the weight of the engines can make her tilt over on to a wingtip. Take off is as you would expect with a tricycle type undercarriage, building up speed then a yank on the elevator to make her rotate, due to the high wing loading and fairly long grass on our strip the take off run was quite long before she would unstick. Once in the air and up to speed she felt solid and responsive to aileron input but a little soft on the elevator, although it is not soft enough to be a problem. A bit of rudder is helpful in the turns, as she seems to drag her tail a bit.

Single engine flight with the .25's is the biggest problem, there just isn't enough power to gain much altitude and the best thing to do is just throttle back and dead stick it in.

Twin OS 40 FP's

 Although increasing the wing loading to almost 25oz a square ft, performance is understandably much better, and she really does fly on rails, single engine flight is not bad at all, a fair bit of yaw into the dead engine is the main thing to deal with, and the rudder seems to cope with this ok. As long as maneuvers are executed gently you can fly around on one engine with out to much problem, it is a good idea not to let her slow down to much though. Get her to slow and then apply full throttle and it will flick over and in if you haven't much recovery height. Despite the wing loading landings are a buzz and touch and go's are great fun, you need your engines set up well though, if one quits on climb out your in the brown and smelly!!.

Basic aerobatics are no problem, loops, rolls, stall turns etc are all positive and axial but spins are more like a spiral dive which I think means that I need to try moving the C of G a bit farther back, this would probably explain the soft elevator and maybe make turns better with out needing rudder.

Some thoughts on setting up twin engines

 Some of my experiences while flying this twin.

Use a servo for each engine, it is easier setting up the linkages accurately. If you have a good computer radio, slave the port engine from the main throttle channel so that you can switch it to idle while you start the starboard engine, if you cant do this a "y" lead will work but wont be as functional. Set each engine up as if it were on a single engine plane, get one engines mixture settings right then stop it and get the other engine set up. Don't worry about synchronizing the engines, it is much more important that each will run reliably, I cannot get my OS 40 FP's within 150rpm of each other on the ground but once in the air they seem to balance them selves out. Keeping both engines running is the most important thing.

After the first flight's of Double Trouble I decided to fit OS 40 FP engines. This meant that I had to beef up the engine mounting points. The OS 25 FP's that I originally fitted were ok on Gnat type mounts but did wobble about a fair bit due to the size of the gap between the wing and the engine mount allowing the ally "U" section to rotate back and forth slightly. I decide that I had to let the engine mount run all the way back under the wing, to give it more support, I did this using larger ally "U" section that I folded at work. I am lucky to have access to a brake press and can fold ally to any dimension required, I realize that it may be difficult for some people to get aluminum in the sizes that I have used , but it is so convenient for me to make things in this way. With a bit of thought I'm sure alternative methods using plywood or similar materials would be just as good, and maybe even lighter. The pictures should make it easier to see what has been done.

I use a separate servo for each throttle, programming my FF9 to use the port engine throttle servo up as a slave to the main throttle, this allows me to start the port engine first, flick a switch which sets the engine at a high idle, then I can get the starboard engine started with out the port engine revving high as the starboard engine is fired up.

I couldn't wait to try her with the OS 40's in, and flew when I shouldn't have, it was far to windy and our field has a forest at one side of it, if the wind is coming from the trees it causes an awful lot of turbulence as it breaks over the top of them and as I was approaching for a landing, at about 6 feet up, the wind caught her and slammed her into the ground. My own fault for flying that day, result was a cracked down pipe center pod where the under carriage fixes, and bent tail booms. To save time (and because I'm lazy) instead of making new parts, I patched them up, bracing them with ally. This has obviously added to the weight, and she now has a wing loading of around 24oz a square foot. This could be reduced but it is another thing on a to do list with far to much to do in it already !!.

Future Modifications

If I get enough time to get around to doing it I would like to make some new tail booms possibly using small diameter plastic pipe. A new center pod would be a good idea too as well as some lighter better looking engine mounts. A slightly larger elevator or a more rear ward C of G would be good to try as I think it could do with more response in this area Reducing weight is a priority, she seems to float quite well but in her current state weighs in at 9 1/4 lbs.

Things still to do

I want to try mixing the throttles with rudder although I haven't figured out how to do this yet, I heard that some twin floatplanes do this to help taxiing on water, but I reckon it might be interesting in the air to. Full left rudder giving full throttle on the right engine and tick over on the left and vice versa should maybe make for some interesting maneuvers. I've also got to get the C of G back a little and I cant move anything around to achieve this so I need to loose some weight of the front and lighten up the back, I think really its time for a bit of a re-think for the booms and engine mounts.

The ally booms tend to bend if you have a heavy landing and I would like to replace them with something "prettier", and also make the engine mounts lighter and made out of something more readily available. Also de-rigging the model needs consideration, because I have a large van, I never thought about making the wings removable, I don't bother to take it apart.

11/04/2004  Rest in Pieces

Well I suppose it had to happen sooner or later, I had been thinking about completely re doing Double Trouble and maybe using her wing on something else, well, now its a must, while doing a 'Split S' for a fast flypast I rolled her inverted and dove for the ground, EH!!!, no elevator response, nowt, in she went like an arrow and just stuck there, A real Spot landing winner!! You can just about see the nose cone about eight inches down at the bottom of the center hole, couldn't get it out so we gave it the last rights and filled it in, I can wait, the way things are going in Oxfordshire they will be building a housing estate on our patch soon, when the footings go in I'll be there.