Fox 15...Saint or Sinner?

I recently came by a couple more, so I decided this afternoon to grab five other ones reposing in a cigar box, and run them all. Each had the same prop (the equally despised Master Airscrew 8-4 (works well with the Fox for some reason, and the flywheel action of all that weight helps starting, too), the same fuel (25/10 with both castor and syn), and the same single Fireball Hot Long, which really got a workout. The design included everything from the first Steel Fin, Steel Fin with offset plug, monoblock with slant plug, and monoblock/slant plug with muffler bosses.

Out of the seven engines. five started and ran well. One of these needed more breakin, as it wouldn't hold a lean needle.

Of the two that didn't go, one popped on each flip, but that was it. The other one I flooded, worked out the flood, finally started and ran for 30", and stopped abruptly. And that was it. I didn't fuss over them for long once they showed reluctance to go.

Overall, a decent showing for the little Fox, at least I thought so. Maybe some of you think that 5 out of 7 isn't good enough, but I think it breaks the negative stereotype. Another interesting thing...I couldn't find my crummy Hobbico tach (it wants blinding nuclear fission-like sunlight, a albino colored prop, and wants to touch same in an intimate way to get any reading), but the later slant plug motors didn't seem to be running any faster than the earlier Steel Fins at full leanness. This despite Peter Chinn's MAN Engine Reviews that showed the latter design to have a lot more power.

The engines are cheap on the swap meet circuit and even on ebay, they are extremely light for a .15 (only the K & B Greenhead 15 is lighter), and they work really well on Jr Streaks, Jr Rings, Flying Clowns, Acromasters, etc. Some will 4-2-4, even. They kind of accumulate, like Babe Bees, or McCoy Redheads that are missing NVAs, so you should have some in a dusty part of the workshop.

And they will start. Five of mine did, anyway.

I have a couple of steel fins and five or so slant plugs. All seem to run well. Several of the slant plugs came new in plastic bags when the Factory at Ft. Smith was flooded. Apparently some boxes were damaged so the engines were cleaned, oiled, and re-packaged.
A couple of suggestions are to try a Fireball short on the difficult ones, and use all castor on any that appear to have a lot of time on them.
When Duke Fox ran "Duke's Mixture" in the mags he once found performance not being up to par, and he determined the cause to be a little on the edge of specs here and there. He tightened the tolerances and brought them back up to snuff.

Currell;

The late '50s design was the steel fin - which I do not believe is the often hurled and sometimes reviled slant plug aluminum case engine we had in the '70s.

While I think the steel fin is a better engine, my two slant plugs always ran fine. Back in the '70s, I had one on a 15 size Flite Streak and the other on a Sig Akromaster, and both ran fine. I must admit that I have often wondered what it was about the slant plug version that made people want to throw them...

V/r

Glen;

Put a magnet to the fins. If it sticks or at least is attracted to it, then you have a steel fin. These were made in a fashion similar to the old McCoy Redheads.

Some may not like them, but I always considered them good engines.

V/r

Did PGF Chinn's article include the measured ballistic coefficient of the two motor types? He measured everything else...

My apocryphal data suggests that the cast-case motor has considerably lower ballistic coefficient and thus cannot be thrown nearly as as far as the steel-fin. I have not had the opportunity to conduct wind-tunnel tests, so if the data is already available that would help me considerably.

>Well, like some of my favorite ladies have said "I don't smoke or >drink and two out of three ain't bad."
>Jim

><snip>
> Did PGF Chinn's article include the measured ballistic
>coefficient of the two motor types? He measured everything
>else...
<snip>
> Brett

These two posts reminded me of a story my brother told me. While stationed at Edwards AFB (he's now a retired Rocket Scientist) when he was much younger.

He had a date with a lady English Teacher from Desert High School (Scorpions...we were students there for a year, my Sophmore, his Senior, '61). They played "Scrabble", of all things! First go, she made a nice word, "ball". Hmmmm! He looked at the letter blocks he had, the board with her word, and used every one of them, to make "ballistician". One who calculates ballistic trajectories of various projectiles. She told him that was enough of that, the date was over, and that was THAT!

Moral of the story? Well, it seems to me that the moral of the story was to not show all your smarts, when making a move on a potential mate. Opinions may vary. Apparently, he took this as an omen, and has remained unencumbered with females, instead has (I think) at least 3 (1:1 scale) sailplanes, and flies them as much as he can stand. I wish I'd been more interested in Scrabble as a young man. Steve

PS: I had two steel finned Fox .15's, bought new. Second one from AHC with a Ringmaster Jr. They were ok, considering Blue Blazer or Testors #39 was their diet. OK Cub glowplugs, 8-4 Tornado nylons.

Steve: Good story, but to make the word ballistician, starting with ball, your brother would need 8 letters. The most letters you can hold in Scrabble is 7. Currell

Bet they didn't last long using those fuels! The Testors 39 was noted for lack of lube...I used it too, but not a lot.