Fox .35 Engine Footprint, other choices?

[Avaiojet]

I have this project destined for a Fox .35. I already have a nice one but it's for the Flite Streak.

I'm thinking this model may weigh a bit more than I expected, so what other engine options do I have? Possibly a larger Fox or something else that will fit the same footprint.

Yes, the fuselage is basically completed, beam mounts, "T" nuts and all. Currently set up for a Fox .35.

I really don't want to cut that stuff up for the engine change.

BTW. The McCoy red head won't fit, but that still a .35.

A nice 40 would be great.

Thanks in advance.

Charles

[Clint Ormosen]

The only one I can think of is the Double Star 40. The Fox 35 mounts are pretty narrow and the crank snout is very short. Not much bolts right into a Fox footprint.

[Ron Cribbs]

It wouldn't take, but a few minutes to epoxy pieces of hardwood dowel into the pre-existing holes. That way you can start fresh. Are you unable to get to the blind nuts?

Ron

[peabody]

Look at an LA 46....If there is room toward the tail, I believe that just two new blind nuts are all that's needed.....the rear holes for the ox become the front for the LA

Have fun!

[Motorman]

Not sure but I think a Brodak 40 bolts right up.


MM

[Clint Ormosen]

Look at an LA 46....If there is room toward the tail, I believe that just two new blind nuts are all that's needed.....the rear holes for the ox become the front for the LA

Have fun!

A swing and a miss.

The the LA isn't even close. The fox is at least an 1/8" narrower, but thanks for playing.

Sure, you can grind, drill, and file to make anything bolt in. Some people's idea of "fit" must differ from mine.

[Clint Ormosen]

Not sure but I think a Brodak 40 bolts right up.


MM

No, doesn't bolt right up. However, if you hog out the holes a bit, you can force the Brodak in. Or you can drill out the motor lugs. You'll probably have to grind the engine beams a bit wider near the top or the Brodak crankcase probably won't fit between them. Unless the beams were made too wide for the Fox to begin with.

Btw, I don't recommend doing any of this.

[Clint Ormosen]

It wouldn't take, but a few minutes to epoxy pieces of hardwood dowel into the pre-existing holes. That way you can start fresh. Are you unable to get to the blind nuts?

Ron

This is the right idea. If you make new holes and can't get to the blind nuts, you could use threaded inserts.

[Chris Wilson]

I have this project destined for a Fox .35. I already have a nice one but it's for the Flite Streak.

I'm thinking this model may weigh a bit more than I expected, so what other engine options do I have? Possibly a larger Fox or something else that will fit the same footprint.

Yes, the fuselage is basically completed, beam mounts, "T" nuts and all. Currently set up for a Fox .35.

I really don't want to cut that stuff up for the engine change.

"I recently found that the Enya SS30S and Enya 19 share the same bolt mounting pattern as the Fox 35."
"I have an OS .25F that fits Fox.35 mount drop in. "
"O.K. Cub 29/35, some O&R. Early Fox Rocket 35. Early Fox 19. "
"Thunder Tiger 36, although the shaft length is a quarter inch longer. "
"Fox 29."

http://www.clstunt.com/htdocs/dc/dcboard.php?az=printer_friendly&forum=103&topic_id=374747

(That took about 5 seconds to find the answer on Google and much longer to type it out.)

[Avaiojet]

Guys, thank you for the replies and suggestions.

Yes, I thought about cutting the top of the fuselage and removing the "T" nuts and epoxy the holes with hard wood. Starting from scratch. The ply nose ring isn't in place yet.

I was hoping the Fox 40 would be a shoe in? although I know nothing about the Fox .40?

I thought the LA 46 would be a bit much. I have one in a ARF Pathfinder and it flys a bit fast. Working on that.

Thanks again.

[john e. holliday]

No matter what engine you use, the speed or lap times can be controlled once the airplane is happy in it's flight envelope.   If too fast go to longer lines.  Of course once you change one thing then other things happen.  But most of all make sure the airplane is happy.   

[ChrisSarnowski]

Have a look at this web site: http://www.clacro.de

In the section "Design", click on Measurements.

It gives various measurements for different engines, and you can compare to see if you can swap something in.

-Chris

[Chris Wilson]

Have a look at this web site: http://www.clacro.de

In the section "Design", click on Measurements.

It gives various measurements for different engines, and you can compare to see if you can swap something in.

-Chris

Nice chart but its a pity that nothing is the same measurement as a Fox 35.

[John Stiles]

Won't the Fox .29 bolt right in? I have a couple of .29s that actually seem a little hotter than my .35s.

[YakNine]

Hi Charles, how overweight could it be, Bolt the Fox on and let er rip you might be surprised. T.J.

[John Craig]

If you might need just a little more muscle:  A hemi-head on the fox 35.  Modify your existing crankshaft counter weight as demonstrated on past posts.  Up the nitro in your fuel  to 10%-15%. Use a more efficient propeller.

[John Rist]

Nice chart but its a pity that nothing is the same measurement as a Fox 35.

The chart is in MM.  Don't forget 1 mm = .04"  The fox hole pattern is 38.4 wide.  Lots of 38 in the table.  Only .016 off.  I know it's considered unthinkable by some but you can enlarge the hole in the motor to make it fit.  Shaft length is another matter.

[Steve Riebe]

You could always consider one of the modified fox 35's that are out there, like the L & J, or the Randy Smith. There's also the ceramic version, these all seem to have a little more guts then the standard ones. I have an L & J on a nobler and I really like it.  I don't think you will find anything with the short front end like the Fox. .

[Avaiojet]

You could always consider one of the modified fox 35's that are out there, like the L & J, or the Randy Smith. There's also the ceramic version, these all seem to have a little more guts then the standard ones. I have an L & J on a nobler and I really like it.  I don't think you will find anything with the short front end like the Fox. .

Steve and others, thanks for the replies.

 I haven't epoxied the ply nose ring yet, so the nose could be altered. I could actually alter it for any engine but would rather not.

Upgrades? I don't and never liked altering engines, improvements or not, especially paying someone for the upgrades. Not that there's anything wrong with that, I just don't have the money.

I mentioned the Fox .40. Anyone got one?

[Andrew Hathaway]

Which Fox .40?  There's one based on the early combat special/Rocket case that shares the bolt pattern of the stunt .35, then there's the BB .40 Gold Rat Race based on the early 35X, which has mounts 1/8" wider apart.  And there's the LARGE round .40 of the early 70's, which dwarfs the Fox .35, but is supposedly a fair stunt engine.  Also the large case, coffin backplate, bolt on venturi/carb schneurle .40s, and a slew of compact .40s based on the MKIV combat special, none of which are really "stunt" engines or close to fitting in a Fox .35 stunt's shoes.  None of the above is all that great of a substitute for the .35 stunt.

There are a handful of other Fox engines that will fit the .35 stunt mounts, but the .35 is the largest displacement stunt engine of the series.  Of course the early .29 that shares the .35 case will match exactly.  The 3 bolt backplate .19, .201, .25, and the 70's bolt-on intake .19 & .25 baffle engines, all share the bolt pattern but have longer crankshafts, and different needle locations.  The .19/.25 ball bearing schneurle engines can bolt in the stunt .35 mounts with a little trickery but again, they're longer, heavier, and don't run at all the same.  The early combat specials (Series I-early Series III) along with the early red head Rocket .35s, are bigger, and heavier than the stunt .35, but they'll bolt in the same mounts, but once again they don't run like a Fox stunt.  There are other vintage engines that may bolt in, or come close, but remember the Fox .35 was more successful than those other engines, so there's nothing to be gained there.

If the concern is a lack of another Fox .35, there are scores of them on Ebay at any given time.  As long as you avoid the pristine collector bait, and "rare" specimens, it's easy to get a good Fox .35 that just needs a little TLC for little $$$.  The TLC takes far less time than breaking in a NEW in box Fox .35.  If you need more power, run higher nitro fuel.  All the stuffer backplates, hemi heads, fancy needlevalves, and exotic piston/cylinders won't make a Fox .35 stunt much more powerful.  You can smooth the shakes, you can move the torque curve, you can prolong the life, but it's still just going to be a Fox .35.  If you really need more power than you'll want to just mod the plane to fit the more powerful engine.

[Avaiojet]

Andrew,

I'm impressed. You really know The Fox engine and was very gracious with your reply.

Thank you for that.

Possibly I'm underestimating the Fox 35.

Now you have me interested in knowing the weight that engine can take through the pattern?

Nobler pilots, what do Noblers weigh in at powered with a Fox .35? ? Or other models fitted with the Fox 35?

[Randy Cuberly]

Andrew,

I'm impressed. You really know The Fox engine and was very gracious with your reply.

Thank you for that.

Possibly I'm underestimating the Fox 35.

Now you have me interested in knowing the weight that engine can take through the pattern?

Nobler pilots, what do Noblers weigh in at powered with a Fox .35? ? Or other models fitted with the Fox 35?

I believe a good stock Fox .35 can handle a Nobler at anything up to about 46oz or so very well.  I've had a couple of Fox 35's that were highly modified in a 51 and 52 oz airplane ( Both Thunderbirds at about 610 sq in area).  This certainly is not ideal but they actually did fly quite well.
In truth Noblers seem to fly best at around 42 to 44 oz with a Fox.  I had several of them like this in the 1970's and early 1980's.

The Geiseke Nobler seems to like more power but will fly well with a Fox 35 at about 38-40 oz.

Randy Cuberly

[Avaiojet]

Hi Charles, how overweight could it be, Bolt the Fox on and let er rip you might be surprised. T.J.

TJ, good question.

Guys, thanks for the reply and information.

Well Randy, you and TJ got me thinking, so I weighed what I have as far as all the pieces.

Wing 8.5 oz.
Fuselage 6.4 oz.
Rudder .5 oz.
Stab & elevator 2.5 oz.
Flaps 1.5 oz.

The wing is built but still needs completing, No bellcrank, and landing gear blocks have to be installed. Plus the weight of .125" wire gear and 3" or 2.75" wheels. No covering or dope yet either.

Fuselage needs the underbelly and wood under the stab. No HDWE yet.

Flaps are built up, no hinges, and covered with silkspan and two coats of dope. Bit more to go with dope.

Stab & elevators are built up and covered and doped. No hinges.

Rudder and stab is built up and covered with two coats of dope.

"Without" the HDWE, wheels, tank, gear/gear blocks, hinges, wing covering, and coats of dope plus odd and ends, the model weighs in at 20.4 oz. Unless I did my math wrong.

Here's another thing, nothing is assembled, glue epoxy, that adds up also.

I believe the Fox .35 weighs 8 oz.

Wing covering, coats of dope, Robert's 540, rattle can paint, the weight is sure to get up there even though I'm being as careful as I can.

With the nose not completed, now would be the time for a complete engine change.

I don't believe there's any .35 as light as the Fox?

Plus, You can still buy them new!

Thanks again for the replies.

[Ron Cribbs]

The Fox .35 weighs between 6.5-7oz

I went out and compared the Fox .40 and the Fox .35 bolt pattern. They appear the same distance front to back, but are roughly 1/8" off side to side.

The case on the .40 is much wider also. It could be made to work if you enlarged the holes and cut the bearers a bit. Not that I am suggesting that.

This is the Fox .40 I used to compare. It's of the newer compact case design.

[Dane Martin]

good call Ron. i was gonna say, the fox 35 is lighter than an OS 25 FSR both with no mufflers. the fox 35 can pull a fair chunk of weight. plus, if it's for scale or sport, not worth worrying. the fox will definitely do it.

[Ron Cribbs]

Yeah Dane,

My Ring weighs 38 oz and it stills hauls that lead sled around well enough.

Charles, If you stick with the .35 you can send it off for a Lew Woolard rework and you will be happy with that.

Ron

[Ron Cribbs]

Keep in mind the Hemi head from Fox is not how it was designed by Marvin Denny.

A good hemi head will actually reduce compression to give you a stronger low end when in 4 cycle. The 2 cycle is roughly the same but with a softer transition from 4-2.

The Blue Magic head was a good design if you can find one. You can contact Randy Smith and see if he can help.

[Robertc]

Double Star 40 weighs 6.5 oz.  The ball bearing version weighs in at 6.9 oz.  Not the easiest to come by though.

[Avaiojet]

All good replies and good posibilities.

I have my old stash put away in a few boxes. I'm going to dig up my HP .40 R/C. Watch it be in the last box I look in. 

I have a few other smaller CL engines, but only the one Fox .35.

I had the HP in a VK Cherokee.

I'll have to get a venturi and NVA.

Could work, but I believe it may be a bit heavy.