Hi guys, what engine will give me the best performance for 3D on a 90-120 plane a 125 four stroke like the Saito or a 26cc gas like the GR-Pro
thanks

stick with a glow 4 stroke on that size plane

Whats your flying weight going to be, the way I see it is if you are going to be 9 lbs or more you will probably want something with more power for all out 3D performance. In that case you might want to consider a bigger engine, I have a Aeroworks Yak 54 120 size and it will come in around 10-11 lbs. A Saito 150 or 180 would be perfect for it but those things suck glow like no tomorrow. And at about $20 bucks a gallon for glow versus $2 a gallon for gas its hard to compare. I have the MLD-28cc gas motor for my plane and it weighs the same as a Saito 180, it has 2.8 hp and will swing a 18x6 no problem. So if its going to be under 9 lbs stay glow, but over go gas.

As has already been said, depends a lot on the flying weight but a Saito 125 and a decent 26cc Gas are 2 different power areas.
It also depends a lot on which airframe - some just aren't built to hang a gas engine on them. (In fact some shouldn't have any engine on them at all).

I wouldn't put a 26cc plane on a 90-120 sized plane.. quickly becomes a flying brick

Theres a bunch of us doing it on the Yak 54 90-120 from Aeroworks, Im still in the process of getting mine together but I went this route because others have been successful with the setup. Mld-28 motor is same weight as Saito 180.

I am not saying it won't fly

However if you went with a lighter more powerful glow engine the performance would be night and day. On small planes .5 - 1 pounds makes a big difference in how they fly. Unfortunately it's pretty hard to explain unless you try it for yourself.

I get what you're saying, I guess its a matter of what you're willing to sacrafice.

He stated he wanted best 3D performance,weight is not an option then.

The LHS has a SPE 26. I bet it does not weigh as much as my saito 120. I sure wish I could afford to put it on my showtime 90, and give it a try.
Alan

The SPE26 0n a showtime won't be enough power for 3D but will be fine for sport flying. The only problem with the SPE is that if you want the cowl on the plane you will need to do some major cutting to get it to fit. If you want good 3D performance try the YS110 or OS 120AX (2-stroke)

For 3d work I would go for a 120ax, ys110 or saito 125-150, but OS runs happy with lower nitro, ys is pure power and let you put the tank in the CG but drinks a lot of 20-30% nitro, and Saito is easier to tune using 15-20%nitro .... eeeem I know I`m not claryfing anything but if you like to go gas then go for a 50cc plane for good 3d performance

bernard what airplane are you leaning towards? that might help out with engine choice.

I,ve got the showtime 90 with a Saito 125 in front but it has not enough power for good vertical pull outs.I've change the prop to a 16x4W it's a little bit better but still not good enough.

a 120ax would be great

Sorry I forget to mention that I'm thinking of putting the MLD28cc in front cause it weight just over 1.1 kg with muffler and ignition.

A 2.5 pound motor in the showtime 90? [X(][X(]
Thats not factoring in the ignition pack and switch is it?
Its probably 3 pounds then.I bet they do not include the weight of the sparkplug either?

a 120AX can swing a 17x6 Vess 9400 making t a great prop for 3d ing and some decent speed on a 25% WH Edge ....on a plane that size considering all the weight penalties of a 26cc gas motor, battery and ignition i wouldnt do it..... however on the next sze bigger

This has been exactly my dilema,,,,AW .90-1.20 Yak,,,,what to put in the nose???? Saito 180 or the 28cc gas??? Decisions Decisions!!

i'd go with the 180, it only weighs about 31 ounces .....im sure the gasser weighs a considerable amount more, plus thnk of all the lead youll have to add to the tail if you put the gas engine in it

I have a Showtime 90. I've had several different motors in it, SPE26, CRRC26, OS120AX , YS110and now a Evo26. I havn't flown it with the Evo ( waiting for good weather) but the other 2 gas engine were NOT enough power for 3D. The OS120AX and the YS110 were similar in power, both have very good power for 3D. I did not have any balance issues that couldn't be solved by rear mount rudder servo and moving battery around.

Gas engines in this size plane are not going to be enough power compared to the glow equivilant.

Gas is a waste of of money in this size plane, and 9 times out of 10 it adds too much weight and effects the performance of the plane while not giving you enough power to 3D the way you want.

The only way to really get a 26cc engine working on this size / weight of plane is to put a tuned pipe on the engine. That will wake up the engine and give you 500-1000 rpms which is a night and day difference on any engine.


rcplanenut: I think you are going to run into similar issues with this gas engine as well. However add the pipe to it and you will be happily surprised.

i had a saito 150 in the nose of my plane and installed a mld 28. the weight is almost the same. when you weigh the saito, muffler and engine mounts vs the entire mld with ignition everything just about the exact same. im curious on the os 120 i don't have one but how could it spin 9400 rpm with a17/6 when the specs call for 9000 rpm peak with a 15-6 recomended prop.http://osengines.com/engines/osmg0650.html have you tried using 30% heli mix on your saito 125 on that showtime. that mld will destroy that cowl because it is large and will require alot of cutting.

I tached mine the other day with a vess 17x6(wood) the manual recommends from 15x8-16x10 but i like the performance the 17x6 Vess gives me http://www.rcuniverse.com/forum/m_3998256/tm.htm i think they run best in the 9k range

now that i think of it i have seen a os120 in the old 68" extreme flight yak, i believe that the weight come in around 8-9lbs on those. it did have very good pullout in a hover but i don't know what prop he had on it. it was short live though because the motor died in a hover and met its demise very early into it's life.