Just Bagged a Fox .15

Thanks. I had another .15X, but it is put away. It's Phillips head screws were all chewed up, couldn't remove the head. I used a fine hack saw blade to cut the bolts as there was enough clearance to cut without touching the head or crankcase fins. Then I wound up with too short of stubs to grasp. Will need to drill bolts and use very fine Easy Outs to remove, too much trouble.

This one looked a little different, the other one might have been an earlier one given a slightly different muffler bolting being vertical instead of to the lugs on each side of the crankcase fins.

Nice Grab George you got a home picked out for it ? Eric

getback wrote:Nice Grab George you got a home picked out for it ? Eric

Midwest 33-in (838 mm) profile Curtiss P-40 Warhawk profile CL.

The first Fox .15X had no provisions for muffler and the crankcase was smooth with no fins.

The next iteration (that I have) included muffler mounting holes above and below the center of the exhaust stack, and included the fins (?) on the crankcase bottom. I think all remaining versions of the "X" had those fins.

The last one I have has muffler ears as well as the over/under drilled holes. I notice yours does not have the holes drilled over and under the exhaust stack.

Of course there may be more versions.

All of my X's live in Texas...naw, naw, they are all CL versions!    

Here is a pic of the ones discussed plus a couple of mufflers:


 
George

Forgot to mention...NICE CATCH!

Hope you are going to hog out that Peace Pipe a bit.

Hope you enjoy it. Tough break on the other .15.

I guess you know now that drilling the cap head off the screw is the way to go.
Most times those screws loosen up when the engine gets hot.

Looking forward to seeing that P-40 finished!

Ron

P 40 Warhawk !! Nice choice with that Fox 15 x it will make for a good flyer and look good too .Eric

nice steal! I look forward to seeing that baby fly

I have built and flown all of the Midwest warbird series planes. I'm down to my last one as I sold my ME-109 48" span at last years swap meet. The .15 size series are cool. Currently , I have a Medallion .15 on a ME-109 33" span. The P-40 is one that rarely shows up. I'm also quite fond of the Fox .15's. Neat little engines that do pretty well. I have a few of the steelfin version which I also like. It's sad that the .15x was discontinued for the schneurle ported version. George also pictures the over and under muffler. A very poor way to attach and can damage the engine as the screw holes go through to the cylinder and can push on the liner. I drill and tap the sides of the muffler and use a hose clamp. Not the best but if you don't go overboard you can snugly hold the muffler on without distortion. Ken

Thanks Ken and GBC for your inputs. Ron, you're right, the way to go is with socket head screws. TDbandit, getback and rcnut14, yes, that engine and plane combination is the right ticket. The Fox engine came in yesterday. It is very clean, has light barely discernable washer impressions on 2 of the 4 mount holes, appears to have been run very little, has gobs of compression. Missing are 2 3-48 screws mounting the head, but those screws are commonly obtainable. I will replace all screws with socket heads. It is like a new engine. Checked with an OS 761 muffler for the Max .10 Scheurle. Exhaust opening matches but holes are spaced tight enough to not work. I will run this unmuffled.

I checked the weight, it is only 3.6 oz., whereas the OS .15FP is around 5.5 ounces. This is the right ticket for the Midwest P-40.

I haven't given up totally on the other .15X. Probably on a cold winter day that I've got nothing else going on, will figure out how to extract the remaining 3 studs embedded in the crankcase. If I can somehow remove, if threads are damaged, could drill and tap for 4-40 screws.

One thing I have noticed about the Fox .15 (steel-fin, X, or Schnuerle) is that they do not like to be over-propped. Mine seem to run best on an 8x4 or a 7x6. The different versions of Foxes just spin it faster or slower. Of course this is for general sport flying.

Larger props seem to pull it down off its power curve.

George

George, thanks for sharing, an interesting tid bit of info on this engine. I also found the Peter Chinn's observed similar in his engine tests of the Fox .15X.

http://sceptreflight.net/Model%20Engine%20Tests/Fox%2015X.html

Peter Chinn wrote:In general, a prop size no larger than 8x4 (F/F) or 7x5 (C/L) would be advisable for the 15X if high performance is required. This applies not only to the standard engine on mild fuel but also when hotter fuels or higher compression ratios are used, since the b.h.p. peaking speeds are then also higher. We would, in fact, suggest that an 8x3-1/2 Top-Flite prop or any other "fast" 8x3-8x4 prop be tried for F/F. An 8x4 Power, for example, should give a static r.p.m. of not less than 12,500, rising about 1,000 r.p.m. on 20-30 per cent nitromethane and a further 1,000-1,500 with high compression.

On 5% nitro engine peaks at 14,000 RPM, which is different than say the Enya .15-III that peaks at 12,500 RPM. Engine likes higher nitro.

http://sceptreflight.net/Model%20Engine%20Tests/Enya%2015-III%20CL.html

I'll keep this in mind when breaking it in and propping it.