GP Extra 300 .40 size what engine?
 

I have a GP Extra 300 .40 size with a Thunder Tiger PRO .46 engine it is underpowered!! I read that many have installed OS 61FX. Someone at our field suggested installing an OS FX.91 since it is similar size to the 61 and just a little heavier.

My fear is that the wing loading may be too high creating a new problem.

Could anyone add some advice on this.

RE: GP Extra 300 .40 size what engine?
 

Well if it still flies pretty light on its wings with the TT46 on it your only real option would be to step up to the next size engine. That would put you in the 60-90 size class. That class is kind of odd since most 60 size 2-strokes weight the same as 90 size 2-strokes. If you have the ability and room to move your battery back far enought to compesate for the added weight of the bigger motor go for it. DO NOT think that some other "40" size engine will bring your plane to life because it WON'T. The TT.46 gets great reviews and isn't the strongest thing out there but is a real decent engine in the forty class and has a real large happy following.

If the plane sucks now putting a bigger engine in it is either going to make it a lot of fun to fly, if the wing loading isn't to bad or make it snap happy. If you fly the plane rather fast then you will probably love a larger engine. Your landing speed will go up of course but so will your veretical performance. A great engine to look at in the 60-90 class is the OS .90 2 stroke. It has, just like the TT, a great following.

RE: GP Extra 300 .40 size what engine?
 

A guy today had a 40 size with the 91 and a 15 by 8 i think. Needless to say it was a great combination if you 3d and such. He could easily keep up with a 40 Size PC-9 with a 46 ax.

RE: GP Extra 300 .40 size what engine?
 

Mine flies very well on an OS50. I would think a 70 four stroke would be ideal.

Anything else, well if you want to hover, buy a helicopter. Its not 3D ship by any means, the control surfaces are too small for alot of things that a Funtana or something would do.

RE: GP Extra 300 .40 size what engine?
 

A .90 seams to me to be overkill in a model this size. I think you'll be happier with a .60 size. I'd recommend the OS 60.

RE: GP Extra 300 .40 size what engine?
 

2fun,

A 91 2 stroke in the plane will be way overkill. The size prop you will need may even be a problem with the ground clearance not to mention things like airframe vibrations, firewall reinforcement, weight, wing loading, etc...

If you do the 61 then you will have a good match with nore than enough power

What prop are you using on the 46? To little prop or too much prop can also be your issue

RE: GP Extra 300 .40 size what engine?
 

Try an APC 12-4, or 12.25-3.75 on the TT 46 Pro, along with a Tower/GMS/Hobbico tuned muffler. That should help the vertical considerably & not cost a lot of level speed (you should still get 60+ mph). The 46 prop change & mild hop-up is quick & cheap & it will tell you whether or not you actually do need more punch.

If you really do need more power, go for the OS 50 SX, rather than a .61 engine. The 60's are only moderately more powerfull than your TT 46 Pro & are a lot heavier -- and as already noted, you will need to add even more weight in the form of ballast --- maybe for no net gain.

RE: GP Extra 300 .40 size what engine?
 

Thanks for the input...I will look into the prop and muffler option and if it does not help then it looks like the larger 2 stroke option -- Not an OS 91.

I need to check but I think it has an 11x6 prop now. It will be interesting to see what a 12 inch prop will do.

RE: GP Extra 300 .40 size what engine?
 

If you haven't tried a APC 12x4" prop you haven't really seen what a 46 can do. You'll love it. The tower muffler is what I run on my 46ax.

Dave

RE: GP Extra 300 .40 size what engine?
 

If you want to try for a little better combination with the .46 Then the APC 12.25 X 3.75 suggested by Britbrat or the APC 12 x 4W mentioned by Dwm are both good combinations for your eng/airframe.

Another route if you want to spend about sixty five bucks is a Nelson 1/4 wave pipe (Ultra Thrust Muffler) from Performance Specialtys in Nevada. This offers the highest bolt on improvement with no tuneing problems than anything else you could possibly do and far better than any empty can muffler. I use them on a number of my airplanes where performance is the objective.

I also have the Extra you do and I rescued it outta the dumpster and rebuilt it to use as a 'Beater'. Hung A TT .61 on it and not in an ideal orientation (needed this beater quickly at the time). The battery is just behind the fuselage servos and this took care of the CG. Rather than spend money for a new cowl or time to whittle one outta lumber, I just whacked out a clorox bottle. I little wax dulling spray inside the much CA'ed canopy helped minimise the uglies there.

It has been one sweet flyer for four or five years and I always win the peoples choice award for the best flying uglier than Snot airplane. ;) That engine/airframe works very nice together and as has been already said it is not a 3D airplane.

John

RE: GP Extra 300 .40 size what engine?
 

I have the OS 70 4-stroke in mine. Flies beautifully.

RE: GP Extra 300 .40 size what engine?
 

i have a 46 ax on mine and its not so bad maybe a little underpowered but its not so bad. try putting a 11X6 prop it will go a little faster than a 12 X 3.7. I did try both.

I forgot to mention, make sure you remember to retune the high end needle when u change the props.:D

RE: GP Extra 300 .40 size what engine?
 

LoL, 40 sized aiplanes need 90 sized engines, and 60 sized planes need 120 sized engines(i.e. funtana). :D