Bartwoffee

I have an old Royal Products P-38 that I acquired with 2 Fox .45's used for power. The previous owner has passed away, so I don't know if this airplane has ever flown, but the engines don't show any wear at all. The plans call for .40 - .60 power.

I have 2 new OS .55AX's that I was going to install, but this would require some additional cutting of the cowls. I would like to put RCV SP engines in this plane so I don't have to do any cutting on the cowls and ruin the profile or scale appearance. I'm thinking either the 60 or 90 versions of this motor. Both are heavy, but have a lot of torque.

Does anyone have any experience with RCV SP applications? Any recommendations for a P-38 that has a wingspan of 74 inches and weighs about 10 pounds?

HellcatAce

My Feedback: (6)

A close friend of mine flies his Royal P-38 with a pair of old OS .45's and it flies very well and plenty fast. The bigger RCVs have pretty long mounting dimensions. The 90SP is 4 3/4" from backplate to thrust washer. I know for sure because I measured both the 90 and 120 at the LHS yesterday planning for another project. I would make sure you check the overall length of the 60 and see if it will work. Those RCV's are heavy though as you mentioned and I think any more than the 60 would not fit, and be overkill at the same time. I agree with wanting to spare that profile. Royal kits are always very close to scale compared with most others out there.

saramos

I have the 90SP and would think that it would be too much engine for the Royal P-38. The 60 may even be a bit of a challenge to install. You have to take into consideration the muffler and carb. It would be cool to see a pair of large 3 blade props on the plane.

Scott

Bartwoffee

Thanks HellcatAce and saramos. I got the .55AX's because they were just a little bit newer than the Fox engines that were on it. I haven't flown any Fox engines since I was a kid (a loooong time ago), and didn't have much success with being able to keep them going in flight. I don't want to try the single-engine capabilities of this model, so dependability is high on my list.

I like the idea of being able to swing large multi-blade props on this plane, so the RCV looked interesting. I agree the 90SP would probably be overkill, and would have big weight and installation issues. The 60SP will fit as far as the overall dimensions of the engine, but I do have some concerns with the muffler.

Bill

saramos

You can check my gallery for photos of the 90SP in my Top Flite Spitfire. I still had to cut a small hole in the side of the cowl to allow clearance for the throttle linkage. Like the Spitfire, the deep chin of the later models of the P-38 (the Royal kit being the J) should allow concealment of the muffler. You will need to either position the firewall, or make some type of extension box to mount the engine at the right location for the spinner since it doesn't mount to rails like a conventional engine. Another consideration is that these engines seem to run hotter and greater care must be given to cooling. Good baffling and adequate airflow will be important for reliable operation. Doubly important on a twin.

Scott

Bartwoffee

Thanks Scott. The Spitfire looks GREAT!. How did your ducted fan cooling work out? I've been worried about the cooling issues, but the builder included some additional airflow to the engines already. I don't think the mounts will be a problem.

Bill

saramos

The fan provides good cooling. I went with the cooling fan for a couple of reasons. The main one was to minimize the cutting of the cowl, and to have the engine as concealed as possible. The second was simply a desire to try a different solution to a problem. It does add another layer of complication and more parts that can potentially fail. Because of this, I would hesitate to recommend it in a twin application. If you can get your cooling with good baffling, a good air inlet, and an outlet 2 to 3 times larger, that's the better solution. An engine failure in a twin, as you have pointed out, is a situation you want to try and avoid. I have a Royal P-38 kit tucked away. When the time comes, I plan on going either with the 60SP or go all out electric. I really like the idea of turning close to scale props, and not having anything hanging out of the cowl.

Scott

Bartwoffee

I think electric would be a good setup. YOu can twist the props in different directions and help the tracking quite a bit.....plus there isn't as much possibility of one engine quitting in flight. Now, if they would just sound like a "real" motor....

Michael211

My Feedback: (1)

I have seen on Ebay just once a J'Tech in-cowl muffler for an OS 91 4-stroke engine it said. I don't know if you can buy them new or not anymore, but it looked interesting. It was a very flat looking muffler (much like the J'Tech Pitts style mufflers for 2-stroke engines) but it looked like it had a short pip with threads on it to screw into a 4-stroke exhaust port.

Anybody know of other options for exhaust for 4-stroke engines other than the traditional 35 degree bend pipe with cylindrical muffler on the end? Seems like there should be more than just that 1 style of muffler for 4-strokes.

Sounds like a really sweet P-38 project! Be sure to post some pics of it ASAP! 60SP's would seem like an ideal match swinging large diameter 3-bladed Master Airscrew props! [>:]

- Michael