Author Topic: sig mustang / what engine? (Read 5055 times)

John KruziK · « **on:** January 09, 2010, 10:20:14 AM »

I got this mustang stunter from G.S.C.B. swap meet. Needed recovering but was really cheap! And I have always liked this model. After striping the plastic covering off , I found the plane to be in good shape, no repairs. After reading posts about how heavy plastic parts are I decided to cut them off and form new balsa parts. Then while fuse was open I cut into wing and remounted bellcrank with on a rod through sheeting. That's where I am so far. Still don't know what engine to use. Or if I should cut into tank area to see whats in there. John

Leester · « **Reply #1 on:** January 09, 2010, 05:10:15 PM »

It looks in great shape, if you can find out who built it ask them about the tank. I think they were designed for 35's so an OS 35S or 35 FP should do the job. Keep us updated I'd like to see more.

Douglas Ames · « **Reply #2 on:** January 09, 2010, 06:46:56 PM »

Alot of guys here in Tulsa use a syringe for refueling (Brodak's) marked in ozs.
Try refueling it with a known quantity of liquid.

John KruziK · « **Reply #3 on:** January 10, 2010, 10:14:41 AM »

I have an OS40 FP I was thinking of using, but plane was originaly designed for a Fox 35. The OS is several oz.'s heavier. I don't want to add weight to tail.
A few more pics. showing some more weight reduction. Foam removed with a soldering iron. John

Leester · « **Reply #4 on:** January 10, 2010, 11:23:21 AM »

You might want to keep an eye out for a Brodak 40, light weight and plenty of power for that plane.

Warren Wagner · « **Reply #5 on:** January 10, 2010, 01:21:10 PM »

Quote from: John KruziK on January 10, 2010, 10:14:41 AM

A few more pics. showing some more weight reduction John

Hi John,

I was curious....are you going to cover the lightened wing with tissue and dope, or a heat-shrinkable plastic film?

Cheers.

Warren Wagner

Clint Ormosen · « **Reply #6 on:** January 10, 2010, 02:33:49 PM »

I use a Brodak 40 w/ 10.5x4.5 prop in my Mustang and it performs pretty good. The Brodak is about 2 oz lighter than an FP. I did have to squeeze in a 4.5oz tank.

John KruziK · « **Reply #7 on:** January 10, 2010, 03:15:21 PM »

I'm going to cover wings with ultracote film. Paint or dope the rest, I try to stay away from dope, as I sometimes have an allergic reaction to it. Back to my engine choices I also have an Enya 35 a little heavier than Fox 35, a little lighter than OS40. And I don't know what fuel tank is in plane. John

Terry Bolin · « **Reply #8 on:** January 18, 2010, 10:32:25 AM »

Post some pictures when you are done. Look forward to seeing that.
Terry

Tom Niebuhr · « **Reply #9 on:** January 19, 2010, 07:22:03 AM »

As long as you have gone this far, I would replace the tank to avoid any possible problems

Randy Ryan · « **Reply #10 on:** January 20, 2010, 06:18:39 PM »

HMMM I may have to break down and do this to my Sig Stang, I really like the airplane, but its heavy.

Bruce Perry · « **Reply #11 on:** February 02, 2010, 10:42:34 PM »

Dude,

Be VERY cautious of the the wing now that it is cut open like that There are no spars in it and it will flex with plastic covering. It would flex with tissue too but it's gonna be a noodle with plastic. I know there are others that purport this to be an acceptable method of building but I'm very suspicious. Be careful that's all.

B

john e. holliday · « **Reply #12 on:** February 03, 2010, 08:55:41 AM »

I have done foam wings like that several times with nothing bad happening. Of course I glass the center section as I don't use spars. If the sheeting is attached to the foam correctly there should be no flexing.

John KruziK · « **Reply #13 on:** February 16, 2010, 07:19:59 PM »

As it sits without any covering , the wing is stiffer than either of the twisters I have. John

John KruziK · « **Reply #14 on:** February 18, 2010, 12:29:43 PM »

Thanks for all the info. I still don't know what engine to use . I have fox 35 6.5 oz, max 35s 6.7 oz., enya 35 7.8 oz., or a max 40fp 8.3oz. . These are what I have available any suggestions ? Thanks John

Balsa Butcher · « **Reply #15 on:** March 11, 2010, 03:56:06 PM »

Go with the 35-S. Light, adequate power for that design and does the pattern on 3 1/2 ounces of fuel. If I remember correctly there is not space for a tank much bigger than 4 ounces in that design. If more power is needed a Brodak 40 fits into the same mounts but plan on more fuel consumption.

Clint Ormosen · « **Reply #16 on:** March 11, 2010, 04:36:21 PM »

Quote from: Pete Cunha on March 11, 2010, 03:56:06 PM

Go with the 35-S. Light, adequate power for that design and does the pattern on 3 1/2 ounces of fuel. If I remember correctly there is not space for a tank much bigger than 4 ounces in that design. If more power is needed a Brodak 40 fits into the same mounts but plan on more fuel consumption.

You and your 35-S's.........

Randy Ryan · « **Reply #17 on:** March 11, 2010, 07:18:46 PM »

Quote from: Clint Ormosen on March 11, 2010, 04:36:21 PM

You and your 35-S's.........

SSSSSSSSSSSSSSSSSSSS SSSSSSSSSSSSSSSSSSSSSS

.35SSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

That's what I'd use

Gene O'Keefe · « **Reply #18 on:** March 12, 2010, 07:33:39 AM »

I would go with the FP 40 and add weight to tail if needed - I think you would be better off with the extra power of the 40 ...(JustMyHumbleOpinion)

Geno

Randy Ryan · « **Reply #19 on:** March 12, 2010, 08:32:38 AM »

I have a .40FP in mine, the .35S would be more then adequate.

Jim Kraft · « **Reply #20 on:** March 12, 2010, 09:48:28 AM »

I have watched Jim Lee fly his with a Fox 35, and it always fly's great. It has won classic at Sigs contest more than once, even though Jim says it is overweight.

John KruziK · « **Reply #21 on:** March 12, 2010, 04:32:19 PM »

Thanks for all the info. I decided to cut the tank out . It looks fine so I will reinstall, but make it removable. And I am going with the 40FP, it fits in original mounting holes. John

Randy Ryan · « **Reply #22 on:** March 12, 2010, 07:07:40 PM »

Quote from: John KruziK on March 12, 2010, 04:32:19 PM

Thanks for all the info. I decided to cut the tank out . It looks fine so I will reinstall, but make it removable. And I am going with the 40FP, it fits in original mounting holes. John

Unless your FP has been properly reworked prepare for some screaming wild flights!

Clint Ormosen · « **Reply #23 on:** March 13, 2010, 09:45:05 AM »

Quote from: Randy Ryan on March 12, 2010, 07:07:40 PM

Unless your FP has been properly reworked prepare for some screaming wild flights!

Yeah, I hope that's not a box stock FP 40. Runaway city!

Bill Little · « **Reply #24 on:** March 23, 2010, 10:00:18 PM »

Quote from: John KruziK on March 12, 2010, 04:32:19 PM

Thanks for all the info. I decided to cut the tank out . It looks fine so I will reinstall, but make it removable. And I am going with the 40FP, it fits in original mounting holes. John

Hi John,

I hope I am not too late. Did you take the back plate off the tank? Definitely do that as since it has been setting for an undetermined amount of time, there could be congealed castor in there and that will give you fits.

If you use that FP 40, and it has not been reworked, use a 4 pitch prop and let it run in a 2 cycle. They do not take well to a 4-2 run in stock trim.

Better yet, if you can re-drill some holes in the Motor Mounts, use the 35S.

Mongo

Randy Ryan · « **Reply #25 on:** March 24, 2010, 06:21:54 AM »

Quote from: Bill Little on March 23, 2010, 10:00:18 PM

Hi John,

I hope I am not too late. Did you take the back plate off the tank? Definitely do that as since it has been setting for an undetermined amount of time, there could be congealed castor in there and that will give you fits.

If you use that FP 40, and it has not been reworked, use a 4 pitch prop and let it run in a 2 cycle. They do not take well to a 4-2 run in stock trim.

Better yet, if you can re-drill some holes in the Motor Mounts, use the 35S.

Mongo

Bill,

Even with a 4 pitch it'll sing! I use a 10.5x4 on my FPs and even in a 4-2-4 its fast. I have a .35S in my GB Nobler, sure wish I'd have tried one int the 'Stang, Maybe when I refinish it.

Tom Niebuhr · « **Reply #26 on:** March 24, 2010, 07:55:57 AM »

Don't be afraid of some power. The LA .46 is possibly the best choice for the Classics that originally had .35s. Use a aluminum backplate (same as FP). Change to a forward needle valve. (I use a ST assembly. Runs are faultless and consistant. The engine get stronger afteer about 10 flights. There is never an overspeed problem.

More power does not mean speed.

This set up will pull through bad air with ease. Except for the above change, the LA .46 is an off the shelf engine that does not require any after market rework.

Randy Ryan · « **Reply #27 on:** March 24, 2010, 10:57:03 AM »

Tom,

An LA.46 in definitly a great choice, but that wasn't in his list of available power plants.

John KruziK · « **Reply #28 on:** March 26, 2010, 05:15:30 PM »

If I go with the OS 35s , would it be OK to fill mounting holes redrill and use threaded inserts instead of blind nuts. What should I use to fill mounting holes? And yes Bill I removed tank to check it out and will make it removeable. Thanks John

Balsa Butcher · « **Reply #29 on:** March 26, 2010, 05:48:20 PM »

I think if you check you will find that the mounting pattern for an FP engine is the same as that of the 35-S. The issue will be the length of the fuselage and exhaust/needle valve alignment. If you do use the existing holes you will have to modify the front of the fuselage because the FP is much longer than the 35-S . If you do go the new hole route plug the holes with wood dowel material using slow-dry epoxy. Personally, I wouldn't use threaded inserts but I have heard some builders like them.

John KruziK · « **Reply #30 on:** March 26, 2010, 06:10:39 PM »

I would want to use inserts because I dont want to remove the balsa block to use blind nuts. A few pics of progress.

Balsa Butcher · « **Reply #31 on:** March 26, 2010, 07:04:21 PM »

It looks like the challange will be to drill accurate holes in the engine mounts, tough to do when the fuselage is already assembled . Inserts will definitely make that easier. One thing to be careful of is how close the larger holes for the inserts will come to the edge of the beam mounts. As I mentioned, I'm not a big fan of inserts but in this case they may be the best way to go.

Randy Ryan · « **Reply #32 on:** March 29, 2010, 06:58:35 PM »

Quote from: Pete Cunha on March 26, 2010, 07:04:21 PM

It looks like the challange will be to drill accurate holes in the engine mounts, tough to do when the fuselage is already assembled . Inserts will definitely make that easier. One thing to be careful of is how close the larger holes for the inserts will come to the edge of the beam mounts. As I mentioned, I'm not a big fan of inserts but in this case they may be the best way to go.

The only problem wiht inserts is that the bearers are only as strong as the thinnest section which is through the rear mount holes.

Jim Kraft · « **Reply #33 on:** March 30, 2010, 10:16:00 AM »

I have used socket head sheet metal screws in maple mounts to hold my Fox 35's in my Dragon, as I had to replace the mounts after the Super Cyclone I had in it shook them loose. I have changed engines in it many times, and it has many flights on it without problems. I did this for the same reason you mentioned. I did not want to cut the top block off, ( bottom block in this case ) to install blind nuts.

Balsa Butcher · « **Reply #34 on:** March 30, 2010, 11:37:05 AM »

I really don't understand the hesitancy to cut the top block off. If it were nicey painted, that's another story. But with a sharp knife or Zona saw, cut-drill-glue-fill. Not only does it rhyme but the job will be done right and the strength of the engine bearers will remain uncompromised. After re-finishing, you will never know the difference.

Bill Little · « **Reply #35 on:** April 19, 2010, 01:07:15 PM »

Well, I am a *little* late to the party, but I would definitely remove the top block, enough to get to the motor mounts. Then put it back with a light covering of fiberglass cloth and epoxy over the whole nose back to the wing joint. Use .5 (five tenths ounce) cloth and wipe all the epoxy off that you can. The removal will never be seen, and it will not harm the nose structure. If it is necessary, epoxy 1/8th dowel pieces in the old mount holes. The weight gain will be negligible, and the strength will go up.

Big Bear

Bill Heher · « **Reply #36 on:** April 29, 2010, 10:13:20 PM »

I would bolt the OS 35S in, it might even match the FP40 holes. If it ends up tail heavy with the .35 play with mufflers, my .35S like muffler pressure and a wet 2 stroke, but that is on lighter ( Oriental / Twister) airframes.
You can always needle it up a few hundred RPM or tip the nitro if you need a bit more grunt.

The .35 seems to plug along steady, and my own experience and a lot of others is that the .40FP will speed up and stay leaned out after a while, making for an excihting last 1/2 a tank or so.

The FoX is down on power compared to the OS, but it is light. Don't know if you have to run mufflers or not- but the OS doesn't care, and a Fox can get a bit testy if the muffler has too much restriction / cuases it to heat up.

dennis lipsett · « **Reply #37 on:** April 30, 2010, 08:55:44 AM »

on the subject of the wing lightening process and the perceived weakness that should result. This was a common lightening maneuver in a lot of the foam wing R/C arfs that once were plentiful. Most used insane amounts of power and did rediculous high stress maneuvers with no apparent failures. However if you want to minimize your worries even though you have foam ribs sheer web in between the ribs leading and trailing edge and then take some bamboo skewers and put them diagonally in the wing from the top of the l/E to the bottom of the t/E. it's very light and you probably will destroy the model before you have a wing failurs.
Dennis