Hi guys.

I want to build a SIG Four Star 40 and I don't really want to over power it so I was thinking of putting a TT36 Pro motor in there that I have lying around at home.

The motor won't quite fit because the cheeks are to high for the muffler to pass over. And I don't really want to trim the cheeks if I don't have to.

Would it be detrimental to lift the motor slightly to clear the cheeks? How important is it to keep the thrust line?

Marcel

A small amount 6-10 mm or so should not make too much difference to your plane, it may reduce the amount of downthrust required .

I do however think that the TT36 will be marginal for the 4*, but if you got it try it, you can always change it later if you are not happy with the performance.

Great plane - enjoy it

I had another look and I have seen pictures of 40 sized engines and cutting out a bit does not look that bad.

I might put a different engine in it, but still curious to see how a 36 will pull it.

Possibly looking at a four stroke, purley for the sound of it. Surfing around I cam across ASP 4 stroke engines. Almost half the price on an OS!!!!

hey,

Keep in mind that your fuel tank should be in line with the carb. If you place the engine to high, you might have trouble with the fuel-feed.
I would keep as close to the trustline as possible. It isn't a pattern plane, so a little bit of difference shouldn't be a problem. But if you build this one right, it will keep you happy for many years.


Personnaly I think a .36 is too marginal.

I have flown my 4*60 with a OS .91 Fx (two-stroke) for years and always was happy with its performance. It may sound overpowered, but to me it felt like heaven, could do all kind of trics, on a calm day it even could Torque Roll, on a windy day it could do knife-edge.

If I would power the 4*40, I would go with a OS .46 Ax.

Just my opinion.

Phil

I have flown my Four Star 40 with a .46LA and it flew great , just not much vertical pull. I bet that a ball bearing .36 would fly it pretty similarly, and the weight is pretty close as well.

You would probably be disappointed in the performance, though. And I don't think you can avoid notching the cheeks for the muffler and needle valve. It really doesn't look bad.

I now fly mine with a .55AX and it is a rocket.

Good luck

Well the reason I want to use the 36 is is exactly that don't want an overpowered plane. The recommended engine is a 30 - 40 two stroke. And the plane is quite old so I am sure if a 30 from back in the day will fly it, a modern 36 should fly it quite nicely.

I have a GP Big Stick 60 with an OS91FX and that thing goes like the clappers. So I fly that when I want to point and shoot and hav unlimited vertical ...

Having an "underpowered" plane you learn how to realy "fly" I think, if you don't have the power to pull yourself out of a mistake you are in trouble. So that teaches good flying skills I think.

So if the 36 will pull it through a loop after gaining as much speed as possible flying level before entering the loop I will completely happy and my objective reached

Marcel

If You understand that the 36 TT will be slightly underpowered, You will be happy. My first Four Star had a Pro 46 TT and for a beginner it was more engine than I needed. If You are wanting a nice lazy flyer, You will love it with a 36 TT. I've had to cut the cheeks on every one I've built. I didn't think it hurt anything.
john

I used to have a 4* about 10 years ago and used a OS 40 FP (the plain bearing like the LA series). It was my first low wing aerie and was great. The motor would fly it but on a windy day it was only just enough! I then put a super tigre 40 in it which was perfect for a little vertical....obviously not unlimited!

I used to have an irvine 36 that out performed the 40FP. You should be fine with the 36, just go with a 10x5 or even 10x6 APC prop for our altitued!

Keep construction light and especially in the tail and I bet you will have a really nice plane with that engine. Since it is a light engine for the design, you really want to be careful about weight in the rear. Use a steerable skid if you fly off grass. Tail wheels are just extra weight in the wrong place. Use a razor plane to taper the elevator and rudder, and replace wood in the back if it feels heavy. Don't put the stab on with epoxy get a good fit and use regular wood glue. Substitute lighter pushrods if necessary. I did those things on a BUSA Stingray of very similar size and kept it a little under 4 1/2 lbs and I thought it was really nice on an OS .40FP. Your TT .36 is much more powerful. Consider an 11x4 prop. I'm guessing you aren't looking for blistering speed, and the low pitch/large diameter should give good pull on verticals. Let us know how it comes out. I think you will really like it a lot if you keep it light. Jim

My Four Star 40 is finally finished

I decided to put my Irvine 46 in my Four Star. Came out a tad nose heavy with the Irvine. Finished building her yesterday and she will maiden next weekend.

Can't wait to take her out for her maiden next weekend.

Happy landings on the maiden Rappy .
My4 Star has had many engines ST .40 ,Magnum fs .52, saito .56 Saito .72, GMS .47 and a OS 46 ax. All pulled the plane really well You should be fine flying it with the 36 but it not going to do the plane any justice . If on a budget ,save for the ST 40 it flew mine nicely.
My favorite combo is the Saito .56 with a 12x7 APC.

Taat's why I opted for the Irvine 46 in the end, rather have power and not need it than that horrible feeling when you need power and it's not there .....

I had so much fun building it that I have decided to build the Four Star 60 next with a Saito FA91.

Would like to build the 120 but that will be expensive because I would have to buy a bigger car to get the plane to the field he he

Don't let a little thing like needing a larger car deter you from a 120 (:-)

I fly the 4* 120 with a Saito 125. Not overpowered, can be a lazy flier or a terror, and it has a great glide ratio for that long slow, gentle touchdown. The plane is truly a joy to fly as I imagine the smaller ones are as well.


Regards

Hi all

I maidened my Four Star yesterday! What an awsome plane to fly. It was very windy in the morning and took 2 or 3 flights to get used to her. Roll rate was very mushy and after increasing the throws found what I was looking for. But in windy conditions she just does not want to land ....

I must say that with the Irvine 46 she is pretty agile. I am not so used to a tail dragger and found taking off at 1/2 throttle hit the spot he he. But she is a tad overpowered to my taste.

Will be putting a Saito FA56 or an FA62 in two weeks time....

This plane just beggs for a Four Stroke :-)