Hello all,

Just starting a new winter build project, a TF Spitfire kit that's been collecting dust for far too long. It's not going to be a "super scale" build, but it will be detailed somewhat, more interested in it being a "pleasure flier" out of the ordinary. I'm looking to get some good performance from it, but have been out of the "performance" two-strokes for a number of years, with most of my flying lately being 4-strokes (YS), DF jets, & electric.

Somehow I just can't see me putting a 4-stroke in this model. Instead I think of the older Webra Speed .61's & Rossi's screaming during a low pass. What modern engines should I be looking at? I don't have the luxury of hanging a pipe out the side of this bird without looking completely ridiculous, so in-cowl mufflers would really help also.

Any and all advice would be appreciated......

Thanks,

Bob

I selected the RCV 90SP for the TF Spit that I am building. I chose this engine for two reasons. 1, being a geared engine, it will turn a 4 blade 15.5 x 12 prop. The other reason was to try and conseal as much of the engine as possible. I am also going to experiment with using an electric ducted fan for cooling. I have some photos in my gallery.

Scott

Super Tigre 75 Top Flite makes a special in cowl muffler and header for this engine. 61 - 75 OK but not recommended for ST90. This combo has a special sound. Three blade prop and spinner and your good to go. Will scream if you want it too.

O.S. 91FX. .91 power in a .61 case. Should fit easily in the Spit. & there are lots of aftermarket mufflers available to fit it. You should be able to find something that suits your taste.

Scott,

I was also looking closely at the RCV90 as it appears to be a perfect choice for slim cowled planes. How has it been for ease of starting & tuning, as well as power compared to a "normal" 4 stroke? Cooling idea looks good also. *LOVE* those exhaust stacks! Where did they come from? I promised myself that this would be a "fun" build & fly bird, but I just seem to get sucked into the "detail, detail, detail......"


Raston,
OS .91 was also up on my list because of the popularity. Will a TF muffler have enough volume for it or should I look at something aftermarket?

Speedster 1919,
I never really considered the ST as the only experience I've had with them was some old Formula 1 .40 stuff years ago. Anything special to know about this combo? Which 3 blade prop are you running? Could be a good option as it is certainly one of the lower cost ones....

Also considering one of the "Jett" motors, although hiding a small pipe would be difficult.

Thanks again,
Bob

At the risk of sounding silly, I suggest a Tower 75 (really). Aside from being cheap, it is a killer engine & the TF in-cowl muffler fits. It makes the TF Spit go like hell & it has a nice whistling howl, like a Merlin V-12 at full song.

I had (note had) a TF Spit with that combo & I am in the process of building another.

WRT the TF in-cowl muffler -- while it is sized to work with 60 - 75 size engines, it can be made to work well with a 90 after a few simple mods. You have to mill (or file if you have spare time) the header inlet opening to fit the outlet port in the engine exhaust stack, plus you have to grind, or file down the "step" inside the header outlet. Works just fine with a 90.

Hi Bob,
I've only run my RCV on the bench so far. I really like it. It starts easily and idles smooth. I don't expect it to be a fast bird using the RCV, but if I can do basic loops, rolls and cubans, I'll be happy. I want to fly in a more scale manner that aerobatic. I know what you mean by being sucked in by the details. The way I made the exhaust was to make one stack out of a product called Sculpt Easy modeling clay. It's a polymer clay that is easily formed. Then it is hardened by baking it at low temp for about 15 minutes. After baking it, I used epoxy/microballoons for adjusting the shape and adding the seam/weld line. Once cured, I use a product line called Alumilite to make a rubber mold and cast resin copies. The tough part was using a dremel to hollow out the stacks. I mounted them onto a strip of styrene and painted them aluminum. I then use an airbrush to paint them with several different colors. I used rust, and a couple of mixed colors that I tried to match to some color photos. One tip, make sure your original is perfect, spending time on it will save you from having to correct any errors on 12 later!

Scott

Scott,

Might have to enlist the help of my wife on that one.... she's the art teacher / artist in the family & works with Sculpt Easy quite often. Now, tell me that they're FUNCTIONAL and I'll be knocking at your door! Gotta keep reeling in my enthusiasm though and keep this project in perspective.

Thanks!
Bob

Bob, unfortunately, they are not functional. I wish they were. I don't think I can fit functional pipes, plus, I have no experience with fabricating with metal. Who knows, if I find I still need weight in the nose, I might take another look. It sure would be nice to eliminate another hole in the cowl!!.

Scott,

There's a company that makes specialized exhaust systems, I believe there name is Kleo Creations or something like that? I saw a picture somewhere of a custom exhaust stack for (I think) a P-40. Might be worth some searching. You could probably get away with something made out of tubing with the RCV being a 4-stroke. Of course, then all that ouly exhaust will be running down the side of your fuse instead of out the bottom of the cowl!

Bob

Britbrat:

The Tower Hobbies 75 certainly doesn't sound silly to me. I run one with an MAS 12x8 at 8600 feet above sea level, zero nitro, and let me tell you, that bad boy boy really hauls *****. Love it !! Have a 2nd one NIB waiting for a plane. Totally realiable ... and comparatively inexpensive. I'd like to see it perform at or near sea level !!! .

Regards,

misterpanda

Bobman 3 blade 11x7 or 11x8 MAS I went Super Tigre for 3 reasons. 1 Top Flite thought it was good enough to make a special exhaust system for P40 and Spit. 2 fantastic price. 3 I read a RC magizine article about the ST 61 and 75 in a spitfire ,that the sound was perfect of the merlin and allison engine winding up and down. I've never heard a real merlin wind up or down so I had to take his word for it. I've heard the big allison ww2 engines in up close in tractor pulls ,but with special exhaust it couldn't be the same. Plus ST lasts a long time and is easier to start than those super tight TOWER 75 which I have 2

-- 8600 ft. You probably need a supercharger for yourself. The Tower 75 is a wild thing at sea level [>:]