Can anyone tell me where to get some information on a GP-42 engine. I cannot find any on the user reviews on the Universe</p>

It is a Thunder Tiger

http://www.acehobby.com/ace/gp_engines.htm

http://www.thundertiger4u.com/engines-c-33.html

Owner's Manual below

Man are you fast or what? Question for you. I am flying a royal 46 on a Great Planes RV-4. It is a little under powered. I am wondering if I would see any difference with this 42. Are all Royals this weak. I have tried a 10-8 all the way to a 11-7.5 prop with the 10-8 being better but not great.

11 X 6 should be the best prop for the Royal

The Royal should be just a little faster than the Thunder Tiger GP 42

O.K. I'll try that first but untill then I have one more question for you. I'm sitting here at the computer while I am rebuilding my surpass 91 which ate the rear bearing. Question is when I put these bearings back in should I use both the seals supplied with bearings one or none. May be a dumb question but I'm wondering about lubrication. And by the way, what did we do befor we could ask these questions of all of the experts on the Universe?

What tach readings are you getting with the Royal?

We just guessed if we couldn't read about it in a magazine

Pop off the shields on the rear bearing. Leave them on the front bearing

I thought that was the thing to do with the seals. When I took the engine apart it had the inside seal still in place on the rear bearing and I couldn't figure out how lubrication would be put through to the front bearing or shaft for that  matter. I fly this motor on a 60 sized inspire which by the way is a fantastic plane. It does not require very much throttle from the 91 to do anything I want or am able to do so I never pushed it very hard. I heard something weird so I grounded it and took apart. Glad I did, If that bearing had come all the way apart I think it would have dumped the bearings under the crank balance weight where clearance is nill.Again I have to thank all of you for your help and to Jeffie 8696, I really don't know yet about the tach readings as I have been doing it the red-neck way, by ear. But after the advise I got from w8ye I shall have to borrow my dads tach this morning. I will let you know. Also just a note, I am just about done with my new plane, a Fun-World 40, and we are gonna try a new motor on it. I bought a Aviastar 53. Advertised at 2.45 horse-power at a cost of $69.95. This too I will have to see to beleive but test bench results are so far very impressive. Thanks again

Hi

There should be a misprint in the advertising...

1.45Hp sound more realistic for an engine this size.

2,45HP is around the power of a 91 2 Stroke.

Saludos,

Jorge

In reality, it is not 1.45, nor is it 2.45 HP for a .91 two-stroke engine.

The 'rated' HP numbers advertised by most glow engine manufacturers, cannot be produced by the engine, in any realistic situation, as it comes equipped from the factory...

If one shims-up the head, loads the tank with the highest nitro fuel recommended AND installs an optimally length-adjusted open tuned-pipe, the engine might make that output on a 'toothpick' prop, that no-one will bother to fly a normal model with...

For most .46 engines, 0.9 - 1.1 HP are achievable, while spinning usable size props (10x6 - 11x7).

A .91 two-stroke engine, running on a muffler, will typically make ~1.8 HP and with a tuned muffler; about 2.0 - 2.2HP.

EDIT: Language...

I've run my Royal 46 for years on an 11/6, 10/8 and 11/7.5 sound too big for it.

The Royal .46 is an OS SF clone.

It should run about the same as the OS does, on props of the same sizes.

I think you are right about the 11-7.5 being too big and I went this morning to try a 11-6 but I didn't have one. Another trip to the hobby shop will solve that. I have always used Master Airscrew because they are cheap enough and pretty tough, anything better? The 10-8 does O.K once it is up but takes off like it has a load of rocks in it and loses airspeed quickly with any type of manuver. Still, the RV-4 handles pretty well. I think I will stay with the Royal regardless of the power just because of how reliable it has been.  0 dead-sticks, knock on wood!

I've used the 11x7.5 propeller once (the plane landed bad and the prop was broken) and the engine seemed to like it (46FX). So I guess the 11x7.5 imposes no much load to the engine as one may think. Definately a 11x6 APC put more load to the engine as far as I remember, and it didn't flew that well with the apc.<div>
</div><div>The 11x7.5 looked different to the other MAS propellers...it looks like an older design, with a little wider blades. So I guess, you are not going complete wrong with this prop.</div><div>
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</div><div>Saludos</div><div>
</div><div>Jorge</div>

I've been using the APC 11/6 on mine. I don't fly this airplane too often, but it does just fine - it's a sport aerobatic type, the old Walt Moucha "No Sweat". Pretty decent sport plane.

Not all props are created equal. According to posted test results the APC gives a load value of 1.2 while the Master Airscrew gives between 1.0 and 1.18 depending on the series of prop. The new 3 series props have much wider blades and load the engine more while the older design has a 1.0 value. Matching one to your engines power curve is totally hands on since the lower a value will let the engine rev higher .
For example my Aviatronics .46 recently turned on the same size props static, identical setup.
APC 11X6- 11,800
MA3series 11X6- 12,100
How any combination will fly once airborne and unloaded is anyones guess and is dependent on the power curve of the engine among many other factors.

I think your right there. It's really left to getting close to the right picth and diameter and from there as my dad says,"put it on and try it". I've been grounded by the rain lately so I haven't tried any but I am stocking up on all sizes that are close and all diffrent picthes and types. If nothing else they look good in inventory!