Author Topic: Prop Recommendation (Read 2059 times)

Randy Ryan · « **on:** January 24, 2009, 08:38:11 AM »

OK all you ol' combateers, I've got a VooDoo and I'll be using a Fox .36X on crankcase pressure, what size prop should I use, 9-4, 9-5?

Paul Smith · « **Reply #1 on:** January 24, 2009, 09:46:59 AM »

I'd use a 9/7 or maybe a 9/6, not smaller. Those older Foxes don't like high revs.

Terrence Durrill · « **Reply #2 on:** January 24, 2009, 02:08:29 PM »

I flew VooDoo's with Fox .36x BB's back in the mid-1960's (still have 3 or 4 of these engines today and about 15 VooDoo's....12 still in kit form

. Anyway, I mostly ran the 36x Fox on 9/7 Top Flite nylon props and sometimes 9/7 yellow Tornado nylon props....Missile Mist fuel/pacifier tanks. This combination gave excellent results and I was never tempted to even try other props on this combination...VooDoo/Fox 36x BB. I assure you that you will experience some hair raising flights

with that engine/plane combination and 9/7 props. The Foxes will run on 10% or even 5% nitro, but they love 25% and that is what you get with Missile Mist. I also used crankcase pressure and hard tanks when I first started out with these planes in the early 1960's, but got on to the pacifier tank when I read a magazine article (Model Airplane News) on the combat model called the Blitz. Crankcase pressure works ok if you can avoid air leaks in the system, but the pacifier or bladder is 100% better....TDurrill

Randy Ryan · « **Reply #3 on:** January 24, 2009, 02:10:57 PM »

Thanks guys, thanks allot!!

Howard Rush · « **Reply #4 on:** January 28, 2009, 06:50:02 PM »

phil c · « **Reply #5 on:** January 28, 2009, 07:34:03 PM »

a 9/7 will fly faster. A 9/6 will pull better through the maneuvers. The 8/8 Tornado nylon might just get you over 100mph, but the first hard loop will slow it down a bunch, and it takes about a lap to get back up to speed.

W.D. Roland · « **Reply #6 on:** January 29, 2009, 08:40:20 PM »

Randy
If this is your first you fixin to have some fun!

Make sure your launching buddy has done this before!
Hold airplane on inboard side of motor mount with left hand.
Hold out board tip with right hand.

Do not hold lines tight.
Point nose 90% to lines(straight ahead)
Launch at 45% or less with elevator level.

At signal DROP airplane with both hands at once

Wing tip weight?
side thrust?

Fox
9x6 rev up or T.F. Power prop if heavy
9x7 of same if light.
Aldrich props if you is lucky

ST needle valve assy
Missile Mist
Believe it or not a 10X6 of same (P.P. Revup)will fly very well tight and fast--and very different strange feel to airplane.

The tornado 8X8 was not too bad and can be smacked it to firm tera some.

So what do we do for airplanes built for binks pacifiers?

Howard Rush · « **Reply #7 on:** January 30, 2009, 10:03:48 AM »

walter weatherford · « **Reply #8 on:** February 02, 2009, 08:20:42 AM »

Quote from: Paul Smith on January 24, 2009, 09:46:59 AM

I'd use a 9/7 or maybe a 9/6, not smaller. Those older Foxes don't like high revs.

If you are using Missile Mist add some caster oil, that fuel only has 18%, My 36X's would come down smokin hot and hard to start, when taken apart, the crankshaft would be blue where the needle bearings touched the crankshaft. It didn't seem to affect tigers near as much. I would add at least 3oz to a quart,that will give you a tad over 25% caster, parts for those engines are getting hard to find. it will only decrease your nitro % to 22.8%.
Do not use those old yellow nylon props, they are too old even if new you are taking a chance of shedding a blade.
I would not use them even if I boiled them, I have had them shed bits and pieces, while flying. Could be a disaster if one came apart while you were starting the engine!!!! 9/7 prop.

Randy Ryan · « **Reply #9 on:** February 02, 2009, 07:49:59 PM »

8-8................8-8....................8-8.............................8-8..............8-----8 HMMMMMMMMMMMMM!?

Never actually flew combat, though I had a ball with combat ships years ago. We used to fly VooDoos on ST on OS .35s on 10-6s. My brother wanted to build another one after all these years so I got a kit and engine adn gave it to him. He built it and covered it with some old rotten silkspan. Then he was tired of it and gave it back to me. I couldn't stand having it laying around, so I recovered it and decided to us the .36X and wondered what prop I should go with. My first guess of 9-4 or 9-5 was figuring I'd need to keep the pitch low to get any acceleration of of the corners, so I wasn't too far off. I've got a 9-6 on it right now and I'm going to get 8-7s and 8s and I'm even going to try Howard's 8-8 suggestion. I don't intend to fly combat, I'm just going to ring it out and have some fun with it. Thanks for the help, I'll post a picture shortly.

Howard Rush · « **Reply #10 on:** February 03, 2009, 08:21:19 AM »

Except for the prop size, Walt has good advice. The small-hub Tornado 8-8s would fly apart when they were new. If you use an APC, get one with the large (D-1, I think) hub.

walter weatherford · « **Reply #11 on:** February 05, 2009, 01:08:02 PM »

Quote from: Howard Rush on February 03, 2009, 08:21:19 AM

Except for the prop size, Walt has good advice. The small-hub Tornado 8-8s would fly apart when they were new. If you use an APC, get one with the large (D-1, I think) hub.

I respectfully disagree with Howard, His Tigres ran well with 8-8's, when he could get them started, a STOCK 36X works better with a 9-7, IMHO, they won't turn the R's that the Tiger will unless modified.

Hothandle

ptg · « **Reply #12 on:** February 05, 2009, 09:41:26 PM »

Hi Randy,

I have long admired your machine work via your posts on SSW.

Your VooDoo and Fox 36X bring back some very good memories. My first combat contest was the ’67 Nats. Flew a Fox 36X on James Mears Raunchy and ended up 2nd in Senior combat. That was the beginning of a long love affair with combat and Fox engines. With the lone exception of borrowing two Super Tigers to use at the Southwest Regionals in Buckeye, AZ in 1970, Fox was it. The SW Regionals was flown over asphalt and there was no way I would risk a Fox! Flew VooDoo(s) with extended booms and various flavors of Foxes for the remainder of ’67. Flew a variety of originals from ’88 until ’93 when Nelsons just made a more compelling argument at the end of the lines.

Anyway, the best overall prop for “X” was a RevUp 9/7 cut to 8.75”. Good speed and excellent streamer pulling. Fuel is important and so is the fit of the piston/liner and the con rod. Loose is the operative word. It will also help to put a couple of small scratch type grooves in the front of the crankcase for better lubrication of the front end. The engines actually run cooler and faster on more Nitro. Since it's just for fun I would recommend Sig 25% Airplane Fuel (20% oil, half Castor and half Klotz) or someone of your talents could just mix fuel if you have access to the ingredients. If you mix be sure to use 20% total oil AND Castor/Klotz 50/50 mix. I still use this oil mix in my stunt engines and have a couple of gallons of 40% left over from 2002 which was about the last time I flew fast combat.

Hope this helps, have fun and thanks for the memories.

Phil

P.S. My JCT co founder was sorta right! I think he just remembers Tryantulas, Granderdogs and Foxes just before he was terminated!

Randy Ryan · « **Reply #13 on:** February 06, 2009, 07:28:40 PM »

Phil,

Thanks so much for that wonderful compliment.

I hope to have allot of fun with this VooDoo, but probably not flying combat. Then again, we have a few guys here playing at it a bit, so I may do it yet.

Howard Rush · « **Reply #14 on:** February 06, 2009, 11:06:09 PM »

Shucks, I wrote a lengthy post with a PTG-Fox story in it, and it got lost. You guys are right about the prop; I'm wrong. PT knows .36Xs.

Greg McCoy · « **Reply #15 on:** May 01, 2009, 10:16:01 PM »

Shucks, I just got to build a Fox Feathers put on a 36X, 8-8 prop and see if it will do an outside loop. LOL

Chad Hill · « **Reply #16 on:** July 23, 2012, 11:35:24 PM »

Quote from: ptg on February 05, 2009, 09:41:26 PM

Fuel is important and so is the fit of the piston/liner and the con rod. Loose is the operative word.

Phil says "Loose is the operative word". I never had any experience with 36X's many moons ago (did G21s and C35s), but picked up a couple lately that are in decent shape except for one possible concern: con rod play. It's definetly noticeable; there is a faint clicking sound as compression is applied by hand. With the backplate off, the rod can be seen to deflect under load very slightly on the crankshaft pin. The rod isn't bushed, so is this looseness normal for a decent used 36X or should I start scrounging e-bay for a couple of new rods? Ran each motor about 60 seconds with no prob. Thanks, Chad Hill

minnesotamodeler · « **Reply #17 on:** July 24, 2012, 06:27:55 AM »

Quote from: Chad Hill on July 23, 2012, 11:35:24 PM

Phil says "Loose is the operative word". I never had any experience with 36X's many moons ago (did G21s and C35s), but picked up a couple lately that are in decent shape except for one possible concern: con rod play. It's definetly noticeable; there is a faint clicking sound as compression is applied by hand. With the backplate off, the rod can be seen to deflect under load very slightly on the crankshaft pin. The rod isn't bushed, so is this looseness normal for a decent used 36X or should I start scrounging e-bay for a couple of new rods? Ran each motor about 60 seconds with no prob. Thanks, Chad Hill

It'll run like crazy like that...for awhile. Same line could be used for wood 9x6 props on the old 36Xs--great performance, engines soon blown. They'll last forever with 9x7 (or 8x8, I agree, on the right [light] plane) but it seems the 9x6 takes it just over its "redline".
*based on my experience in the 60s.

Robert Schroeder · « **Reply #18 on:** August 20, 2012, 09:26:57 AM »

Quote from: Chad Hill on July 23, 2012, 11:35:24 PM

Phil says "Loose is the operative word". I never had any experience with 36X's many moons ago (did G21s and C35s), but picked up a couple lately that are in decent shape except for one possible concern: con rod play. It's definetly noticeable; there is a faint clicking sound as compression is applied by hand. With the backplate off, the rod can be seen to deflect under load very slightly on the crankshaft pin. The rod isn't bushed, so is this looseness normal for a decent used 36X or should I start scrounging e-bay for a couple of new rods? Ran each motor about 60 seconds with no prob. Thanks, Chad Hill

One thing Fox still has is con rods for .36Xs, also, I think is needle bearings. Last quote is no other parts for any combat specials from the first to the last. Not even a needle valve. I just had a few shipped to me when they sent back a bunch of engines I tried to have updated.---Absolutely no luck, and the guy really looked for matching parts.

Bob

john e. holliday · « **Reply #19 on:** August 21, 2012, 09:03:55 AM »

I guess that is why I never became a top notch combat pilot. I flew what ever the latest plane was. Power was either Fox Combat Special or the Super Tigre .35. Props were always 9X7 either white or yellow. Fuel was alway K&B 100. Glow plugs were Johnsons. Lines were .018 X 60 or as close as I could tie them. I did manage to win one of the last combat contests at the old Swope Park site many years ago. Quit combat when AMA said we could not start our own engines in 70.

Chad Hill · « **Reply #20 on:** August 21, 2012, 07:00:24 PM »

Quote from: Robert Schroeder on August 20, 2012, 09:26:57 AM

One thing Fox still has is con rods for .36Xs, also, I think is needle bearings. Last quote is no other parts for any combat specials from the first to the last. Not even a needle valve. I just had a few shipped to me when they sent back a bunch of engines I tried to have updated.---Absolutely no luck, and the guy really looked for matching parts.

Bob

Thanks Bob, I called Sharon at Fox yesterday and she said there was nothing available listed under those old part numbers...