GallopingGhostler

Today, I reassembled an OS Max .10 R/C baffle piston engine. I bought this used off E-Bay, it was in good condition but gunked up. I soaked it in auto lacquer thinner (the only active solvent I had at the time), which removed much of the glow grunge.

The back plate uses a fine paper gasket. To replicate this gasket by hand would take time and it is rather delicate. So, after careful assembly, I used Permatex Ultra Gray RTV Sealant. I took a toothpick, and carefully put down a bead of it along the engine crankcase flange, then carefully bolted the crankcase back cover on.

I will let it harden for a day or two.

It got me thinking. I've used this sealant for my motorcycle head assembly, assemblying a lawn mower crankcase. Thus far it has worked like a charm. AFAIK, the sealant is recommended on transmission case work.

I'm just curious if any others out there have tried sealants for replacing gaskets in model airplanes, what sealant they used, and how much success did they have at it.

longdan

I've used red RTV hi temp sealant on leaky mufflers, both for the connection to the head and where the muffler comes apart in the middle. Its works well.
I used it on one muffler that kept vibrating loose and it fixed the problem without having to loctite the screws.
Another sealant I've used that is very good is Hylomar blue. I've used it on carb joints with good results.
Let us know how the backplate seals.

icegs

I've used it a few times with no issues. These were on older engines that parts are harder to find. I'm currently flying an Enya 46 4C that is put together entirely with RTV after cleaning. I haven't had any issues in the past year with it. I don't think I would try it on anything that is really critical for sealing like a YS, but you should be fine with most engines.

combatpigg

My Feedback: (3)

In the early days of drag racing methanol / nitro engines, fires were pretty common...win or lose.
The problem was usually the seal between the intake manifold and the block. The sealants back then weren't up to the task until they came out with RTV silicone.
The way I understand it [might have the exact facts wrong], GE Silicone was developed as a way to keep those huge window panes in skyscrapers from popping loose and crashing to the sidewalk. One such building had paid staff whose job it was to constantly look skyward so that pedestrians could be warned about falling glass. As the story goes, GE Silicone was the remedy.
I've found that some silicone sealants will allow glow fuel "creep" given enough time, but I haven't tried all of them.
The last sealant I tried I think is called Hysol. I was looking for a sealant that would hold up to heat better than the silicone O-rings that some tuned pipe systems rely on. It failed, too.
For a backplate gasket, if you can Xacto blade out just the semi-circle [out of grocery bag paper], then install it onto the engine....trimming the excess paper after the backplate is clamped to the engine is easy to do.
Given enough time, castor oil will infiltrate tiny seepholes and plug them up if they aren't under any pressure or too much heat.

GallopingGhostler

This is why I have resorted to using the Ultra Gray Permatex. It is supposedly used on auto automatic transmissions, can withstand pressure, heat and the synthetic transmission oil.

Good methodology, combatpigg. I'll have to ask the wife to ask for paper next time instead of plastic. All we have are plastic bags. Another paper that might be useful is the brown paper used to wrap motorcycle and some auto parts in. It looks similar to the gasket material. Would you think that would work?

GallopingGhostler

thanks for the "vote of confidence", icegs. The OS Max .10 non-Schneurle is certainly not a high performance engine, although it is sufficiently torquey to turn a decent sized prop at reasonable (felt) RPM. (I don't have a tachometer - yet.)

Mr Cox

I just make a new paper gasket when they break, i think I have enough raw-gasket material (sheets) for a lifetime of these little engines. Cut the inner diameter, mark where the screws should go and use a hole punch for those, then trim the outer dimension when everything is assembled.

hllywdb

I'm with Mr. Cox on this one. Gasket paper is easy to come by, NAPA, etc... and it has worked fine for years. Takes a bit of time, but then again, how soon do you want to take it apart again?

GallopingGhostler

I've only bought gasket material in the thicker sizes for such as auto water pumps, fuel pumps (older cars with engine driven pump), and etc. To be frank with you, I never considered checking with the auto parts jobber if they had the thinner material, which might be worthwhile since you mentioned it.

Regarding taking things apart, well, I usually like to keep my engines running in peak condition. So, when they show any signs of slight power deterioration or gotten dirty from say a crash, it's time to take apart, clean, devarnish, etc.

About the only thing I got to say about this .10 engine, is that the previous owner apparently never disassembled it. The back was well caked with dried oil. I had to carefully knock it loose.

I could not remove the cylinder liner. That I'll probably have to heat the engine in an oven, let the aluminum expand beyond the steel liner so it can be extracted. I didn't bother to do that. I'll see how far I get, then if all else fails, do that.

buzzard bait

That old OS Max is still a pretty unique and useful engine. What other 3 oz. engine will swing an 8 inch prop and throttle well? My PAW 0.6 diesel will, but with a lot less power. The Enya .09 is good on big props too, but it's heavier.

Jim

combatpigg

My Feedback: (3)

Sure thing, that type of paper could work. The beauty of trying is you aren't spending more than a few minutes to implement the idea and then you get to see how long and how well your idea worked.
Pay attention to how much end play the crankshaft has. When you jab a starter into the spinner on a plain bearing engine, the backplate CAN become a "wear surface".
On most ball bearing engines, the shaft is held captive by a tight fit with the bearings so they are better by design to tolerate the use of an electric starter.
The old OS MAX .10 that I bought from a "car guy" many years ago would break down as easily as a well fit hand gun..so with yours' I gotta believe that you just need to heat the baked castor oil until it says, "Uncle"...and then it lets loose.

GallopingGhostler

Jim, I've got both engines and you're right. The Enya is about the weight of a .15, it's the earlier one with left hand exhaust and a linked exhaust restricter baffle. According to Enya, their .09's are actually 0.099, more like a .10. The OS has a touch more compression.

My first experiences with the OS Max .10 R/C baffle piston started in the late 1970's, some 30 years ago. The venerable all balsa 39" wingspan Top Flite School Master, which would use a hotter .049 (Medallion or Tee Dee) would really haul with the .10. As a rudder plane (no elevator) at full throttle, it would climb out at the 45 degree angle, get up to altitude quickly. This was on a 7x4 Tornado nylon prop (the old yellow ones). At half throttle was like flying with an .049. It would also haul with authority a Sureflite 3 channel 1/2-A J3 foam Cub with a 40 inch wingspan. I never timed the flights, but a 2 oz. tank was more than sufficient for decent length flights. It was this economy that Bill Winter longed for with his sport flyers. The Schneurles are more thirsty.

GallopingGhostler

These legacy engines when set up properly with the right plug, will fire up with only one or two flips of the prop, making electric start unnecessary, and I know what you mean by wear and tear on the backplate.Points well taken, combatpigg, thanks.

ffkiwi

If you can't find thin enough gasket paper, then a typical office manila folder (usually cream or tan) will provide year's of material for backplate and front housing gaskets. This is quite durable material.

My first R/C model (1974) was powered by the old baffle piston Max 10-and it turned a Tornado 9x4! (not very fast admittedly-but still enough to get the model too high for comfort on full throttle). Of course with that big prop it had a remarkably low idle. The tank was from an Ilford film canister (aluminium) with the lid/filler/feed epoxied on/in-ran for about 15 minutes. The model was a David Boddington 'Tyro'-probably not a familiar design to you in the US, but very familiar to UK fliers. Its descendant is still available in plan form on Ebay as the 'Tyro Too' (it was also kitted by Micromold-but no longer available as a kit AFAIK) I flew it with a sort of 2-channel setup-full proportional rudder and sequential throttle, from a Mainstream Gem Digi 1+1.......not a long way removed from your 'galloping ghost' in approach..........

ChrisM
'ffkiwi'

GallopingGhostler

I don't know if this is a spin off of the Tyro. Outerzone.com has one called the Mini-Tyro by David Bodington with a 32 inch wingspan: http://www.outerzone.co.uk/plan_details.asp?ID=558

Yes, I've proportional flown rudder only with quick blip sequential throttle (hi-med-lo). It was a lot of fun. The 9x4 prop is a little aggressive, I've never tried it. I've always thought it's sweet spot was a 7x4 or 8x3 prop, but that's just my opinion.

ffkiwi

Yes it is George-IIRC the original Tyro dates to about '65 or '66 and was a free full size pull out plan in RCM&E, and gave rise to several spinoffs, including the mini Tyro, and Tyro Major. The original looks just like the mini Tyro shown on the outerzone plan-but was bigger at 45" span. Structurally the same-and just like the mini version, it was intended for single channel escapement rudder when originally published.

David Boddington, who only died a couple of years ago, was an incredibly prolific UK designer of sport radio (and the occasional FF) designs. Interestingly-since you raised it, the Mini Tyro was republished last year in the Nov 2011 issue of RCM&E as a full sized plan, with an accompanying article by David's son Andrew. Fully updated for modern R/C gear-but very much the same old mini Tyro as before. Of course with modern gear and modern lightweight coverings, a 0.5 diesel will cart it around quite happily, and if it's a PAW or Schlosser, you have the option of throttle control as well.

Definitely on my build list...............

I had sequential throttle on my original-but it was operated from a separate servo, and controlled by a rocker switch below the single axis rudder stick on the Tx. Nearly 40 years on I shudder at my choice of prop then-way too much load for the Max 10-but it worked! I do recall getting sick of getting a stiff neck doing figure 8s way high-and throttling back to lose height, then doing a slow climb back to altitude. Good training for modern 1/2A Texaco!

ChrisM
'ffkiwi'

GallopingGhostler

I have an admiration for the kits and designers on the other side of the pond. There were some really nice developments there. Yes, I really have an affinity for the rudder only's, they are really fun to fly.

Sorry to hear the passing of another real great designer. I remembered the passing of Ken Willard, Jack Headley, William "Bill" Winter, Randy Randolph, etc. They were all small plane designers.

Ace had a simple push switch on their Pulse Commander for sequential throttle. If one hit it quickly, would change engine speeds without affecting rudder action. It added a new dimension to rudder only flying.

I've never gone to a 9x4 sized prop. My flying was done with a 7x4 prop and for models of around 3 and a half feet of wingspan, performance was sparkling, definitely not underpowered.

GallopingGhostler

I bench ran a couple tank fulls of fuel on the OS Max .10R/C. So far, the Permatex Ultra Gray RTV is holding up on the crankcase back cover.

AMB

Running mostly diesels any exhaust leaks are messy I have used copperkote its made by permatex I think the 2 and 3 piece mufflers leak st the seams, works like a champ
just loosen the long screw, put on edges retighten also at mate of muffler and engine exhaust stack works like a champ no leaks also head gaskets made from aluminum foil or those thin aluminum cake pans
I also have a number of TT10s and OS10s no gaskets available converted with Davis diesel heads martin

GallopingGhostler

It sounds like Martin that Permatex Copper RTV is a good product to use on mufflers. Someone else mentioned that using Coke can aluminum for head gaskets worked for him.

Since I already have the Ultra Gray RTV, I plan to experiment with it on glow mufflers, since glow engines don't get as hot as gasoline engine exhausts. I'll publish my results when I get around to it.

buzzard bait

I've used the copper RTV but it is awfully conspicuous on an engine, so maybe the gray would look better.

The copper RTV did a great job sealing up all the seams on my K&B Sportster mufflers which are notorious for leaking, so it definitely works.

Jim