K&B .09 Torpedo Engine

Interesting how K&B positioned the needle valve so your fingers would get burned by the hot exhaust.....

Even better is when mounted profile you burn your face off with hot spewing exhaust, it's awesome.

Nice engine George, Neat glow plug as well…. Have not seen one like that….Enjoy the restore   …..Have plans to put it on something?….

Thanks, Ken, for the bit of history on the glow plug, guess it was reliable, but others were better runners.

I have a Midwest 33" P-40 Warhawk profile stunt that would make a good plane for it, Robert. Regarding the needle, I believe it is missing the ratchet spring that goes over the needle cover shaft to keep it positioned. Yes, Jim, odd they positioned the needle adjuster on the same side as the exhaust, but the venturi spray bar a press fit, so no swapping sides.

Got an extra Tatone Calumet .09-.19 muffler that I can grind out all the internal baffles, so gets the Castor spray off the fingers. Some time ago I tried it with my Testor .19 Red Head, overheated quickly with very restrictive baffles in place.

I also have the Torpedo .35 which is completely smoked. I'm awaiting that day when I can find a donor piston cylinder. It's quite sad actually. I received the engine from a speed flyer with multiple engines. The grinding on the cases, the worn out piston liners and the disregard for care just baffles my mind. I have a Pet .09 in this box which looks brand new practically but it's wiped out. Now, this isn't a speed engine obviously, but it makes me wonder as to why someone would harm such a gem of a small engine.

I also wanted to make mention of this earlier in my posts. The K&B Torpedo as well as earlier version K&B engines used the taper drive washers. These are typically missing on most because without the nut, it quickly disappears. They're also not easy to come by. Take care of that and insure it doesn't find it's way with the rest of the missing ones.

Ken, yeah, similarly, I got a bastardized K&B .35 Torpedo where someone attempted to cut the piston skirt (somewhat sloppily done) to create SPI on this engine. Fortunately I have a new, unused OS Pet .099-III C/L engine in my stash.



Thanks for pointing out the tapered prop washer as it is a unique part of the engine. I am glad I have the original part. I made one for my OS .40FP R/C out of a small stack of 4 washers, 2 same diameter as the prop drive washer and another two slightly smaller, but of course, the OEM tapered one would have been nicer.


Improvised prop washer stack on an OS .40FP R/C mounted to a Sureflite .40 Cub ARF.

Send me a sketch and I will make you one

706jim wrote:Send me  a sketch and I will make you one

Appreciate the generous offer, Jim, but in this case I'll have to pass. Although I repaired the Cub, I don't have confidence that my substitution of 3/16" foam board for the tail surfaces will truly work, got some warping to relieve. Original was in sheet foam but was destroyed in a move. I'd probably be better off going to balsa.

So until the plane is ready to fly or I move the engine to another plane, for now, it is just a static display hanging from my garage roof.

You definately got a very nice original low time run engine there. Looks great!

Thanks, @NEW222. I temporarily mounted an electric prop just to see if I could turn it. Lo and behold, the engine has been lightly oiled with sewing machine or tool mineral oil. It does turn over freely, has the strong compression of a Medallion .09 with a high compression Tee Dee head. It makes a noticeable loud pop, so @Ken Cook is correct. When it runs, it will have a louder note similar to twin exhaust port engines.

The engine is clean enough that I do not have to disassemble it, just carefully wash the outside with some volatile solvent. Even the head, although some of the paint has been rubbed off from handling appears to have been  so lightly painted, that this is normal. One thing I do notice is that the mount holes are very small, appears that 2-56 mount bolts will work, even the 3-48's may be too large in diameter.

The needle valve has enough resistance that I think it can hold a setting, doesn't appear to need a ratchet spring. Now, I am really stoked.

K&B .09 Torpedo next to a Sportster .45 R/C and Testors McCoy .35 Blue Head R/C.

George, I like the blue head Mccoy. That's one engine I don't have. I was looking for my .35 Greenhead yesterday. I came across the .09 and one I forgot. I have a beautiful .29. Sadly, I acquired this engine from a deceased club member. The pictures don't do it justice as it's a very clean nice example which runs terrific. I think Pete the fellow who originally owned this would be proud to know it's in good hands. Pete was a avid freeflighter usually older traditional models. My .09 however as I mentioned prior isn't a pretty example, it just runs well and I have a thing for these smaller engines.

Interesting about the mounting holes being that small. I would have thought they would have at least been a 4-40 thread. I never would have thought.

@Ken Cook, that K&B .29 Torpedo is a beaut, congrats on scoring it.

It is interesting that my .09 has the factory spray bar mounted with needle on the exhaust side, yet yours and the one in Sceptre Flight's Aug. 1958 Model Aircraft review have the needle on the other side. I gather that with the Champion glow plug, mine must be an earlier production version. Also, it seems my suspicions are correct, the engine article shows engine tore down, there is no retention spring for the needle; with threaded collar, it is a friction fit, ingenious. Another interesting fact is the slightly more powerful Fox .15X is almost an ounce heavier than this Torpedo (3.6 vs. 2.8 oz.). It is almost the same weight as the unmuffled, unthrottled Medallion .09 (2.75 oz.).

Also of interest is that this engine (swept volume 0.0999 cu. in.) is a little powerhouse of its own right on 12% nitro, when compared with the later OS Pet .099 engine (swept volume 0.0981 cu. in.) on 15% nitro. Although the OS is tested with muffling in place, performance curves are similar, not bad for an engine that was in production 15 years earlier. It is also lighter at 2.8 oz. whereas the Pet is 3.25 oz. The comparable 1958 OS Pet .099 steel fin of similar weight was definitely weaker on power even on 25% nitro.


Torpedo .09 engine performance curve (12% nitro), author not identified (although appears that Peter Chinn may have written it) in Aug. 1958 Model Aircraft.


OS Pet .099 engine performance curve (15% nitro) by Peter Chinn in Apr. 1972 Aeromodeller.


OS Pet .099 steel fin engine performance curve (25% nitro) by H.R. Warring in Aug. 1958 Aeromodeller.

Yes, the screw mount holes are tiny, @NEW222. Here, I am comparing it to my Medallion .09 R/C. The engine mount holes are noticeably smaller than the Medallion's: