Author Topic: Reverse rotation Fox 35 crank (Read 4705 times)

Dennis Toth · « **on:** July 26, 2012, 02:00:12 PM »

Guys,
I getting to the point of selecting a bellcrank position in my El Diablo, now normally I would go with front line up, however I have heard that there was a reverse rotation Fox 35 crankshaft at one time. Does anyone know of them? Anyone got one they would care to part with? If so send me an email (I'm in the listing).

Best, DennisT

Russell Shaffer · « **Reply #1 on:** July 26, 2012, 02:09:20 PM »

Just a word of caution - you won't find many left hand props for that Fox. I have come up with Master Airscrew, Zinger and APC, all in 10-6.

L0U CRANE · « **Reply #2 on:** July 26, 2012, 06:18:20 PM »

Dennis,

I believe they are still available from FOX; check their on-line catalog. (Tedious, and you might need to ask the company specifically, if it isn't in there.) Think I saw the CW shaft in a recent visit there, though.

Russell is right about props. However, when Larry S designed the El Diablo, a lot of guys ran Fox 35s on less than 10" diameter props, even on ordinary stunters. The MA prop might be the easiest to trim down to, say, 9 1/2". I think it would be a lot of work, and defeat the engineering, to modify an APC that way. Many wooden Zinger props (used to?) need some reshaping - LE and TE thickness for example - so extra work there. I haven't seen composite material Zinger LH props...

I flew an All American, Sr, with a LH shaft Fox 35 at VSC #1. Practically identical manners (or lack thereof) to standard rotation. Worked well, but be careful starting it, if it sits on the ground. I too often punched the pavement on the follow-through... Probably not a problem with the El D.

I doubt you'd have any comments if you simply flipped the bellcrank to put UP line forward, or put the elevator horn the other side of the elevator (bottom vs top?) ...er, might make landings a problem...

De Hill · « **Reply #3 on:** July 26, 2012, 06:58:18 PM »

Lou,

I believe that Red Reinhart designed the El Diablo.

Dennis Adamisin · « **Reply #4 on:** July 26, 2012, 07:18:03 PM »

XOAR makes VERY nice LH props in wood.

Chris Wilson · « **Reply #5 on:** July 26, 2012, 07:27:32 PM »

So ......... how would the De Sax offset work in reverse?

Not that well I assume!

Randy Cuberly · « **Reply #6 on:** July 26, 2012, 10:55:31 PM »

Quote from: Dennis Toth on July 26, 2012, 02:00:12 PM

Guys,
I getting to the point of selecting a bellcrank position in my El Diablo, now normally I would go with front line up, however I have heard that there was a reverse rotation Fox 35 crankshaft at one time. Does anyone know of them? Anyone got one they would care to part with? If so send me an email (I'm in the listing).

Best, DennisT

Dennis,
I sent you a PM.

Randy Cuberly

Dennis Toth · « **Reply #7 on:** July 27, 2012, 02:18:33 PM »

So did the very early 4 bolt Fox 35 have the De Sax offset? Seem from what I can find they did it in the 50's, do they still have it in the latest version? If they do it seems the way we run them in stunt (4-2-4) it might not matter (hard to tell on a Fox when its losing power of burping)? I guess one way to know is if it has lower rpm for the same fuel (5%N/29%O) and prop from one with a normal shaft. Anyone flown one of these on a full stuntship?

Best, DennisT

Bill Little · « **Reply #8 on:** July 27, 2012, 02:40:40 PM »

Hi Dennis,

I have one in my Fox .35 that is in my AA Sr. I have not had the chance to fly it yet, though.
My thoughts were simply that all the offset in the wing which causes some funny things on take off would be offset by reverse rotation. Still remains to be seen.........

BIG Bear
RNMM/AMM

Dennis Toth · « **Reply #9 on:** July 27, 2012, 05:50:35 PM »

Bill,
Have you run the engine?

Best, DennisT

Bill Little · « **Reply #10 on:** July 27, 2012, 06:16:12 PM »

Quote from: Dennis Toth on July 27, 2012, 05:50:35 PM

Bill,
Have you run the engine?

Best, DennisT

Yes, but not flown it.

I think I need to run it some more to break in the crankshaft better.

I got a few black Tornado pusher props just by chance and that's what I will start out with. They are 10-6.

Bill

L0U CRANE · « **Reply #11 on:** July 28, 2012, 02:12:13 PM »

De, re: El Diablo - I stand corrected and grateful for it.

Thanks.

Garf · « **Reply #12 on:** July 28, 2012, 02:25:43 PM »

If I were to pick an engine to put a RR crank into, it would be a K&B greenhead.

L0U CRANE · « **Reply #13 on:** July 28, 2012, 02:41:22 PM »

Bear, to your #8:

My AA, Sr, didn't need tipweight with the LH shaft. Slight normal torque reaction on the mounts tends to raise the inboard wing, where standard shaft could tend to lift the outboard.

Also, 'standard' bellcrank (leadouts inside, elev pushrod outside of pivot) didn't have any precession kick problems.

Of course, as we've discussed for years, takeoff still needs deliberate care. Step back to make sure the wing doesn't droop before the model lifts off. Afterward, flight forces take care of most other things.

Not much of this applies to the El Diablo, but may be interesting??

As to the DeSaxe offset: It wasn't a large distance to begin with. I think the idea was to put the power push more in line with the rod. It reduced the sideways swing angle on the power stroke, but increased it on the compression stroke. It also shifted the exhaust and bypass port timing numbers...

Except for a very few engines - early Fox, some ST - few companies went to the trouble and expense, for apparently very little gain... Fox Mfg offered LH shafts even in the days when they sold stock DeSaxe engines, so there wasn't likely much difference due to the offset.

I see Garf offered a thought while I wrote this. Reminds me that some engines can be reversed without a special shaft. ENYA engines only need the intake housing turned 90° for reverse operation, and I've recently seen some numbers that suggest shaft inlet timing both ways is quite close. Other engines with a 'square' 4-bolt pattern front end can do the same.

Yeah, the venturii goes to a wierd place, and tank height will take some 'developing' but it does work. And suitable props may be made of unobtainium... - but it is different.

Bill Little · « **Reply #14 on:** July 28, 2012, 03:32:02 PM »

HI Lou,

Thanks for the comments. You may or may not remember the discussion I had here a couple years ago about the flight characteristics of my AA Sr. Take offs were hairy to say the least!

So I pulled out the Fox and stuck a LH crank in it! Health problems have delayed my attempts to see how well it works. Hopefully that will all change in the next year.

Thanks, again!
Bill

Chris Wilson · « **Reply #15 on:** July 29, 2012, 04:56:32 PM »

Quote from: Dennis Toth on July 27, 2012, 02:18:33 PM

So did the very early 4 bolt Fox 35 have the De Sax offset? Seem from what I can find they did it in the 50's, do they still have it in the latest version? If they do it seems the way we run them in stunt (4-2-4) it might not matter (hard to tell on a Fox when its losing power of burping)? I guess one way to know is if it has lower rpm for the same fuel (5%N/29%O) and prop from one with a normal shaft. Anyone flown one of these on a full stuntship?

Best, DennisT

Hi Dennis,
from what I can tell running an engine normally designed to use the lower crank volume swirl to sweep into a massive side transfer port and then reversing that direction will lower its maximum power output and tend to run with a slightly richer needle setting.

In other words it will hold more of its fuel charge in the sump for longer.

But this maybe a good thing for us!

Dennis Toth · « **Reply #16 on:** July 30, 2012, 10:02:04 AM »

Chris,
At first I thought you might have a valet concern but then Garf posted about the K&B being the engine to do a RRC, it seems that the K&B's have the bypass on the opposite side from the FOX and always ran just fine. I intend to use the "stuffer" backplate to take up some of the excess case volume so I don't think it should be much of a problem. Maybe Bill L will get a chance to fly his and give us some flight info.

Best, DennisT

bill bischoff · « **Reply #17 on:** July 30, 2012, 02:56:31 PM »

We did some testing for carrier with rear disc valve, side exhaust engines (K&B 40S, Webra 61) to see for ourselves if the direction of rotation mattered as far as RPM. On back to back tests after rotating the backplate 90 degrees to reverse the intake timing, we measured no difference in RPM.

Chris Wilson · « **Reply #18 on:** July 30, 2012, 04:57:41 PM »

Yet on Fox 120 twin that is actually 2 identical 60 engines with one of the barrels flipped over the 'reversed' pot needs to have its needle set richer in order to run evenly.

I suppose that all engines are different but with a side exhaust Schnurle ported engine the crank direction is nowhere is near critical as the main ports are at the side of the crank swirl (and are fed evenly despite crank swirl direction) whereas the transfer port in a single by pass Fox will either face the hurricane or be against it.

There is a loverly article I can dig up a link to that describes how MVVS speed engines ran with a single bypass port on the 'wrong' side extremely well and it was due to piston windows and crank flow - anyway if someone wants a read I will find it.

Dennis Toth · « **Reply #19 on:** July 30, 2012, 05:30:48 PM »

Chris,
I'd love to see that article. I guess we need to get some run data.

Best, DennisT

Chris Wilson · « **Reply #20 on:** July 30, 2012, 06:35:48 PM »

Quote from: Dennis Toth on July 30, 2012, 05:30:48 PM

Chris,
I'd love to see that article. I guess we need to get some run data.

Best, DennisT

I will PM that link today mate.

Randy Cuberly · « **Reply #21 on:** July 30, 2012, 08:49:00 PM »

Quote from: Chris Wilson on July 30, 2012, 04:57:41 PM

Yet on Fox 120 twin that is actually 2 identical 60 engines with one of the barrels flipped over the 'reversed' pot needs to have its needle set richer in order to run evenly.

I suppose that all engines are different but with a side exhaust Schnurle ported engine the crank direction is nowhere is near critical as the main ports are at the side of the crank swirl (and are fed evenly despite crank swirl direction) whereas the transfer port in a single by pass Fox will either face the hurricane or be against it.

There is a loverly article I can dig up a link to that describes how MVVS speed engines ran with a single bypass port on the 'wrong' side extremely well and it was due to piston windows and crank flow - anyway if someone wants a read I will find it.

I'm not familiar with the Fox twin you're refferring to but the issue could be one of simple load sharing. Typically two engines driving a single shaft will fight each other in phase unless one is set to run about 1% or so slower than the other. It's a simple load sharing rule called "droop". It's used on all load sharing installations of prime movers.

Randy Cuberly

frank williams · « **Reply #22 on:** July 31, 2012, 09:11:26 AM »

So does anyone have a reverse Fox 35 crank for sale?
I checked the Fox website, and although they list several reverse cranks for different engines, they don't list one for a 35.
Any available out there?

Randy Cuberly · « **Reply #23 on:** July 31, 2012, 03:20:28 PM »

Quote from: frank williams on July 31, 2012, 09:11:26 AM

So does anyone have a reverse Fox 35 crank for sale?
I checked the Fox website, and although they list several reverse cranks for different engines, they don't list one for a 35.
Any available out there?

I have a complete engine with one. (Larry Foster modified with all the trimmings,,,New).

Randy Cuberly

frank williams · « **Reply #24 on:** July 31, 2012, 05:06:47 PM »

Randy,
I sent you and email.

Bill Mohrbacher · « **Reply #25 on:** July 31, 2012, 07:19:38 PM »

Stunt 35s have no Desaxe offset. The stunt 19, 201, &25 had it as well as the 29R and the combat special based family.

dennis lipsett · « **Reply #26 on:** July 31, 2012, 09:55:47 PM »

just think, 25 posts on this thread dealing with how to make a Fox 35 run as badly going clockwise as it does counter clockwise. LOL

Dennis

frank williams · « **Reply #27 on:** July 31, 2012, 10:17:24 PM »

Randy,
Having trouble contacting you ... email me at lonestar_77062@yahoo.com re: reverse Fox
Frank

andrew stokey · « **Reply #28 on:** August 01, 2012, 07:27:38 AM »

Frank, is the Fox gonna be in next years stunt plane for the Nats?

Randy Cuberly · « **Reply #29 on:** August 02, 2012, 11:58:42 PM »

Quote from: andrew stokey on August 01, 2012, 07:27:38 AM

Frank, is the Fox gonna be in next years stunt plane for the Nats?

If you ever saw Hiki San fly his Geiseke Nobler with a Fox 35 in it you wouldn't laugh so much. I remember the man with the pipe doing pretty well with one also.
I think everybody should have at least one stunter with a Fox 35... and I don't even particularly like them

However I'm very sure Frank will continue with electric for competition.

Randy Cuberly

andrew stokey · « **Reply #30 on:** August 03, 2012, 06:59:17 AM »

Randy, I have seen Mr G fly at several Nats and it was inspirational. It's sort of an inside joke with Frank. I told him nobody would launch him when he went electric.
Fly anything you want. It's all fun.

Randy Cuberly · « **Reply #31 on:** August 04, 2012, 12:19:04 PM »

Quote from: andrew stokey on August 03, 2012, 06:59:17 AM

Randy, I have seen Mr G fly at several Nats and it was inspirational. It's sort of an inside joke with Frank. I told him nobody would launch him when he went electric.
Fly anything you want. It's all fun.

Yeah, I was sure that was the case Andrew...I didn't mean to sound so serious. I also have no prejudices about what to use to get the job done. Whatever works, works.
Even my Belko long shaft works...and it's really wierd.

Randy Cuberly