What Engine For LT-25?
 

I am building an LT-25 and will need to make a decision on the engine pretty quick. I know the recommended engine size is around a .25 2 stroke. I have a NIB Magnum XL that would work and also have a NIB O.S. FP40 that weighs the same as the magnum. I am betting the Magnum will put out the same power as the FP. I am a real fan of plain bearing motors and am considering the FP over the Magnum. I have owned 3 Senioritas all powered with FP-25s and they flew fine. I think the Seniorita is just a little lighter in weight.

I will most likely pull the radio on my Aircruiser and it has an FP-25 on it that could also be used. So what do you folks suggest?

I do remember one poster stating he had an LT-25 with an FP-40 on it and said it was the funnest airplane he ever had. So thats why I am considering the same engine.

I have a Thunder Tigre 36 in mine and it's a nice match. That being said I don't see that engine available now? A good OS 32 or similar would work well also, the key is keeping the weight down..........A friend has a Saito 40 in his, also a good choice.

Gizmo I bet your 36 weighs about the same as the FP. The Magnum 25 weighs almost exactly the same as the FP-40. And there is a youtube vid of an LT-25 with a Saito 40 titled "Don's LT-25" and this guy makes it look easy. Great video.

I am not a speed freak. I just like to putt around in the sky. I like to sit on the tailgate of my truck and trim the plane to fly on its own and just make an occaisional correction while it flys in a big circle around me. I would buy a 4 stroke if I didn't already have a couple of suitable engines on hand already.

The 36 is light and has a lot of power. My Lt. has the wings flattened out and direct linkage to the tailwheel. It will fly inverted well and does nice outside loops. Haven't flown it for a while but it is great to remove rust!
:o

Well after laying both engines on the plan I think I will put the Magnum 25 on the plane. The plane isn't as large as I thought it would be. Plus I have a Bridi Loadstar in my attic that is just perfect for the FP-40. I have built two other of these planes and flew them with plain bearing 40s and they flew with plenty of power.

Thanks for your input Gizmo. When I get it finished I will post pics. Everything is done except for the fuse. It was a very simple build so far.

Gizmo I am thinking about a direct link to the tail wheel also. I think I will use the plastic push rods that came in the kit fot the rudder and tailwheel and use a pushrod for the elevator. I don't really like plastic control rods.

Did you use the main landing gear that was supplied? I am thinking about cutting a new gear that is a little wider and use 4 screws for attachment instead of the two 4-40s supplied in the kit. I was trying to stick to the plans but I have such a hard time not making changes I think need to be made. Its just a failing of mine. And of course the wings will bolt on.

My wings bolt on, the only way to go. I stayed with the furnished landing gear but use 3" soft foam tires for grass, etc. I used the golden rod push rod for the tail wheel, well supported. Just flatten the wing keeping about a half inch in it. Should fly well! Good luck!!!!!

I had one with an OS FP-25 for several years. It does fine with that motor and will fly the plane, although if 3D or intense aerobatics is what you are looking for, then you probably should go bigger. If you look at the weight between a Seniorita and an LT-25, the flying weight for a Seniorita is 3.75 lbs and the flying weight for a LT-25 is 4 - 4.25 lbs. There is an article about the LT-25 in an old RCM magazine and the guy who wrote it used a Royal .25 in his and it did great. Larger engines (> .25) are just not needed.

Depends what you want to do. With the larger engines it makes for a much more responsive plane and more able to use floats, etc. If you want something to placidly fly a slow pattern then by all means use the smaller engine. I use my thumb to accomplish that when
I want to go slow. There is little weight penalty by going the way I have.

The LT-25 is framed up and sanded and ready to cover. I will use the Magnum 25XLS engine.http://www.rcuniverse.com/forum/atta...mentid=2001144

I had a LT-25 on floats with a OS Max 25 FSR. Had more than ample power..