'73-'74 Fox .40 Stunt: worth re-using in a Nobler?

I have a '73-'74 Fox .40 Stunt motor which I flew for a season in a way-too-heavy Shark 45. I'm considering building a Nobler and wondering if the motor is worth putting in a new plane. Other than the fact that it couldn't pull a ship as large as the Shark, the motor worked fine - a bit high on vibration but did the 4-2-4 cycling as expected. No crashes. What's the general consensus on the relative merits of this design and the fact that it's no longer in production? Maybe get a new Fox .35 and avoid the issue and put the .40 into a practice profile?

Related question: What might be the flying differences between the three Nobler variants: the '52 M.A.N., '57 "Green Box" and the Gieseke Nobler for someone like me, an average flyer who can do the AMA pattern on a calm day but never entered contests. I read somewhere that they're pretty equivalent, but would like to ask the question.

Thanks much

The Fox 40 should be a decent motor. It is not as powerful as some of the modern power plants, but neither is the Fox 35 you are also considering. Aside from the fact that you will have extra weightom the nose, the 40 will give you more power which should help you in less than ideal conditions. It may be difficult finding a muffler for it, however.

The two GA Noblers are quite similar. There are just slight variations due to the fact that George drew the plans for both from memory. The 52 plane is OT legal, the Green Box is not, simply because it came out later. But the differences are not enough to make one in reality better over the other.

On the Gieseke Nobler, he increased the airfoil thickness, redesigned the fuselage, made minor "tweaks" here and there. I like it better (so did he), but it is neither OT nor classic legal. For someone like yourself, if you don't plan to enter contests with it, it really wouldn't make any difference anyway.

Leonard Neumann

Thanks, Leonard. You pretty well summed up the issues that I've been scratching my head over these last couple of months. Also, it's been great reading all the posts in this forum. Great job.

Philip

>The Fox 40 should be a
>decent motor. It is
>not as powerful as some
>of the modern power plants,
>but neither is the Fox
>35 you are also considering.
> Aside from the fact
>that you will have extra
>weightom the nose, the 40
>will give you more power
>which should help you in
>less than ideal conditions.
>It may be difficult finding
>a muffler for it, however.
>
>
>The two GA Noblers are quite
>similar. There are just
>slight variations due to the
>fact that George drew the
>plans for both from memory.
> The 52 plane is
>OT legal, the Green Box
>is not, simply because it
>came out later. But
>the differences are not enough
>to make one in reality
>better over the other.
>
>On the Gieseke Nobler, he increased
>the airfoil thickness, redesigned the
>fuselage, made minor "tweaks" here
>and there. I like
>it better (so did he),
>but it is neither OT
>nor classic legal. For
>someone like yourself, if you
>don't plan to enter contests
>with it, it really wouldn't
>make any difference anyway.
>
>Leonard Neumann

Hi Phil. I had a Sig Chipmunk with the big Fox .40, 1972-74 in it. Not the Super Chip, but the one based on Jim Van Loos model. The only problem I had with the Fox was that it tended to over heat when you least needed it, ie in the last part of the pattern. I later found that it had a "hot" crankcase. This made it lean out and at times sieze. Though it ran fine when it cooled, it always seemed to get hot. Never did this on the test stand and it had a lot of Super fuel through it. On the Super Chip that it is now installed in I made a vent at the top of the nose behind the spinner and two outlets for cool air to flow over the crankcase. As to a muffler, I'm using one for the ST .60. I made a band and with two 4-40 long bolts it works.

Yikes!! I wonder why the .40 didn't catch on and whether this was due, in part, to the "hot" crankcase issue. Mine seemed cool enough, or at least I never noticed overheating effects, and the Shark 45 cowl is not the best for taking heat off a motor. Mostly, the motor vibrated more than I would have wished and caused foaming fuel problems which I managed to iron out with a filter.

Ty M. wrote:
>Hi Phil. I had a
>Sig Chipmunk with the big
>Fox .40, 1972-74 in it.
...snip
>The only problem I had
>with the Fox was that
>it tended to over heat
>when you least needed it,
>ie in the last part
>of the pattern. I
>later found that it had
>a "hot" crankcase. This made
>it lean out and at
>times sieze.

The Fox 40 should be a decent motor in your Nobler application. The motors didn't really catch on, facing serious competition from OS and ST by that time. Also, those gynormous mount spacings may have hurt it, since it would be difficult to stick this mill in an already-built model that (snugly) mounted another engine (like a Fox .35). They didn't add that much go (to be honest) either, although it is noticeable. The overall weight increase, taking the modest power output into consideration, didn't help matters either.

They are stout things that can take a lot of crash damage. The RC boys used them with some frequency.

I bought a garage sale Smoothie with one of these a few years ago. Haven't flown it yet, but the previous owner was happy with it.

Would be pretty good in windy weather.

I always use a filter to keep the bubbles from getting out of hand. I didn't mention the huge mounting area of the lugs. Yep, once you mount that monster, no other engine will fit the same holes. I have the same problem with my OS Max III .35 stunter. In fact it had to have the outside of the lugs ground down to get into the engine compartment. I do wish all the manufactured engines would have to conform to a "standard" like things in the NMRA do. Sure makes life just a little easier.

>I have the same problem
>with my OS Max III
>.35 stunter. In fact
>it had to have the
>outside of the lugs ground
>down to get into the
>engine compartment. I do
>wish all the manufactured engines
>would have to conform to
>a "standard" like things in
>the NMRA do. Sure
>makes life just a little
>easier.

Ty: I can relate. On my OS Twinstack 29s and 36s, the lugs have these little half circle extensions that go half way around the lug holes. You end up cutting into the fuse sides.

I have seen those. Mayby that's why Fox .35's are/were so popular. Available, cheap, and they fit!!

I've got 2 Fox 40 Stunts. Smooth and seemingly powerful on the test block, but, you're right on, the huge crankcase and mounts don't just fit 40 size ships I've already built. So min has never taken to the air!

Very interesting thought you propose....why can't we see more standardization in mount bolt patterns?