hello everyone,

I just recently bought a seagull decathlon. Now I have 2 questions. The first is I want to use a four stroke engine. The maximum size 2 stroke engine is a 46. I'm thinking of using a 60 or 72 four stroke. I'm assuming the crank case dimensions are bigger on the lager four stroke. the problem is that the engine mount is already installed so do I have to replace the engine mount with a lager one? Has any one in the forum used a Four stroke in one of these planes? if so did you have to do any modifications?

Question #2- The kit requires a four channel radio with 6 servos. I already own a futaba sky sport 4 ch. Can I use my radio and buy 2 Y connectors or do I have to buy a computer radio?? Thanks for your time

Tim

There was a thread on this forum about the Decathalon, I beleive he used an AX .46 and wanted more power. A Saito .72 uses the same size case as the .56, which fit into a plane I recently built and was designed for a .46 2 stroker. Should fit with no problem. Other than the usual 4 stroke issues. (throttle exhaust, rocker covers poking out cowl, etc etc.)

I think this plane uses 2 servos for the elevator, you could do it with a 4 channel radio, just use non-reversing "Y" harness.

Andy

I just started the SG Decathlon last night (I'm reviewing it for RCU Magazine). I am planning to use an OS 70 surpass. The firewall holes in the mount are elongated so they can be spread apart.

2 "Y" cords is all that is needed. In fact, the reason for the extra servo is that they use 2 servos on the elevators. Personally, I think this is overkill. I'll be using 2 servos for the sake of the review, but if I were just building it for myself, I would "Y" the pushrod and use 1 servo.

Thanks guys for your replys they are a big help. Im happy I dont have to spend the extra money on the radio. What do you guys think about the saito 82 in this plane? Do you think it is over kill?

Thanks Tim

go with the Saito 72 or OS 70, you do not really need the 82, i am going to order this elegant plane myself very soon, Seagull have gone a very long way towards producing high quality (and very desirable indeed!) airplanes.

I would avoid the 82 also. I have heard that this plane builds a little on the heavy side to begin with, I would hate to have ta add extra weight to compensate for more engine than is needed.

I beleive the ready to fly weight on the plane mentioned on the forums was in the neighborhood of 7 lbs... kind of heavy for a .46.

Andy

Kaitai 22, The Saito .72 is an excellent choice for a .40 size plane, the crankcase is very narrow and will drop right in most .40 size mounts. I am running a .72 in a .40 size Starduster in a Hangar 9 .40 size metal mount with the clamps. Dropped right in. The new .82 from Saito I believe is still on the same size crankcase and is only slightly heavier according to the adds. Since the Seagull Decathalon builds on the heavy size, the .82 might be the best choice. Of course at our club field, the motto is too much horsepower is just enough. We're at 5000' altitude though. The Saito singles in general are very light for their displacement and output. I want to put the .82 into a Seagull Zero which is sitting in the shop, and am looking for flying reports on this engine.

Best regards from old bird.

Ive got a brand new YS63S sitting in a box waiting to put in my Decathlon, which is also still in the box. Just a delay on finances for the radio gear to put in it.

I will be putting this together this week, I am using an irvine 61, had to change the engine mount and do a bit of cutting on the cowl, but as was said earlier, the build weight is heavy, and I agree too much HP is just enough, I would rather throttle back for scale flying, but have the extra power for those less than perfect landings or a windy day, will try to post buid pics.


James

I just got back from the LHS and I just purchased a Magnum 70 xl. The price was right so I could not pass. Has anyone here had any experience with this motor?




Tim

Just this morning, I completed the Decathlon (almost). The only thing left to do is to add the Rx, battery and switch, and with the OS 70 it balances perfectly as is.

Seagull Decathalon completed!! First flights done, experienced guy flew first flight snap rolled the bejesus out of this bird, my flights were less spectacular, but great flying plane, looking forward to learning on it. Have Irvine .61 2stroke. Only mods I have to make is to open the cowl a bit in the back, the bird just got too hot, and rebuild the fuel tank holder to fit some foam and lift it up in the air frame a bit to facilitate fuel flow to engine. Engine was either too hot or I was foaming the fuel. Really like this plane!

I really like this thing too. I have completed it, and done a short maiden flight (Very windy day), but all initial indications are good. I'm taking it out this morning to wring it out a bit.

I've got one of these comming.. Is the .46 FX just too small of an engine for this bird??

I squeezed a Mag .70 fs in mine... It fit between the stock mounts... I couldn't resist the sale price on these engines... Anyone know what the deal is with the open space at the bottom of the firewall ?. I sheeted it up and also closed off the hole for the muffler... I was concerned with oil etc getting back in there.. Looks like it will be a great flyer when finished... Love the size..