I recently purchased the GP RV-4 today and was thinking of using an OS .70 Surpass I had laying around for the powerplant. Has anyone had any experience with this combination? How did it perform?

I have that combo. I had a .46FX to start, then I tried the .70. What a difference, plus I like the raw power of the four-stroke. I wouldn't change it back for anything.
BC

I have one with a 40FX, would love to have more power
Go with the 70, you have one allready, its a good choice

Your plane looks great! Question: What sort of material did you use between your wing and fuse? Doesnt look like wing tape.

I Just started building the same plane and plan on using the same engine, glad to hear others think it's a good choice.

I'm happy for ya

I plan on putting a OS 52 surpass II in mine and flying formation with a buddy who is putting a old OS 61/62 4 stroke. ? is will the 52 produce about the same power as the older OS 4 stroke?? and is the 52 good for this plane??


Thanks
Troy

BCJETJOCK,

You and I ought to try flying in formation some time....I only have a .52 FS, but if you throttle yours way down....

Jerry

I have a OS46FX in my RV-4. Did the flap option too. Flys great fast or slow like the full size.And I'm only an intermediate flyer.

Try a .61 Super Tigre . Make sure you have plenty of cowl ventilation. I built two of them and you can see a difference in the performance. My other has a ST .51, Flys OK.

i recently completed construction of my RV-4 and am very anxious and scared at the same time to fly it. haven't had too much luck with the take off part yet (can't keep them in a straight line)...landings are beautiful though. i also have the o.s. 40 FX and was curious if it is going to be enough power to do any nice stunts or just enough to keep it in the air for a nice days flying? also, how does it do as far as aerobatics? i'm not looking for mad 3D, but i would like to learn rolling harriers and torque rolls at about the most. i never saw a review on it 'til after i bought it and i don't like the tail on the cap. can't get into tricycle's though.[:'(]

You have absolutely nothing to be scared of. This airplane is a fine flier, and mine tracks fine on takeoff. You may want to check the alignment of your landing gear to make sure it is straight. Also check to make sure the main gear is not backward. It sweeps BACK not forward.

As far as your powerplant... The 40FX should pull the plane nicely. You will be able to do loops, rolls and all the standard sport manuevers, but there's no chance of doing torque rolls or harriers. You need great than 1:1 thrust to weight and even with the 46FX I have in mine it does not have unlimited vertical. I don't consider this a limitation, though. The plane really does fly great and it is by far my favorite model. It's just not designed for 3D.

I am placing an OS 91 Surpass in the nose.... should be an interesting proposition..... no flaps (save weight) and we'll see what happens.

Hi Fellow RV4 owners,

I was in the same situation of which engine to put in my RV4. I ended up installing the OS .50SX. Like fun4me2fly, I also installed the flap option. It's nice to have the option of using or not using the flaps. It's good practice. The .50SX works great and it takes up the same space as the .40 and .46 engines. I don't have any four strokes yet but it is just a matter of time before I start using them. I really like the sound of a four stroker.
As far as the wing saddle you asked BCJETJOCK what he used, I'm a little old fashion on this. I still use silicone. I just put a good bead down on both sides of the fuselage, lay a piece of saran wrap over them, mount the wing and let it sit all night. In a day or so you take the wing off and trim the excess silicone off and you have a perfect match.
Keep up the good work and let us know how it flys.

Wayne

Well I have Just finished building My rv4 and have mounted a OS .61 fx that I had for my P-51 onto it. It seemed CG wise that It was going to be nose heavy but I moved my 3 servos back one bulk head and it feels perfect. It just needs a couple of more stripes and it will be airborn this weekend. I still havn't put the cowl on cause I couldn't quite afford the fiderglass cowl. But when I can it will go on. It looks great and I have a good feelin about it. It will be my 4th plane and my second build. I started with a superstar 40 trainer until I had a mid air with one of my friends extra300, then I bought a GP P-51 60-90 and it hasn't left the ground cause its so heavy and I couldn't afford another powerplant yet. I have a SIG p-51 that I have flone.