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Is it possible to run a glow engine without a muffler? Assuming I do it where noise will not be a problem. Or, are the modern engines so engineered that they won't run properly without a muffler? I've got a really old OS .45f without a muffler and before I go through the problems of locating a muffler, I want to make sure it'll run.

Thanks for any responses.

earlwb

Yes the glow engines can run without a muffler. The current engine designs, for some brands, tend to put too large of a bore carburetor on the engines, and that leads to poor fuel draw, thus they need a muffler that is somewhat restrictive to provide muffler pressure to help them draw fuel. But older engines didn't have that problem. The older OS .45 FSR should not have a problem running without a muffler.

wcmorrison

My Feedback: (2)

The engine will be loud. It will probably exceed AMA standards and thus you will not be able to fly at AMA fields. Early RC engines ran without mufflers, and they also used a mechanical arm from the carb to the output to regulate back pressure on the engine. There was no concern about using muffler pressure to move the fuel forward from the tank to the engine (e.g. little carbs with big draw capability). The engines also used pistons with dams on them to segregate the intake area from the exhaust area and were ringed engines.

Along came mufflers with back pressure to feed the pressure to the fuel tank to assist in moving the fuel forward to the carb, ringless engines that turned up a few more RPM, and no more dams on top of the piston plus improved porting. The engines at once became simpler (no linkages to fool with). no rings to wear out and bigger carbs that allowed more RPM. The mufflers got rid of the annoying noise (they are very loud in spite of what has been said).

So I would go about looking for a "strap on" muffler for your engine. It may just run better that way and your club will like you too.

1QwkSport2.5r

Running an engine without a muffler does give you a baseline on power production in respect that whatever muffler you use can restrict output some. Having an open faced exhaust performance figure can tell you how much power the muffler robs from the engine. Often a larger muffler will net nearly the same or better power. Any rpm figures showing more rpm over open exhaust is in effect tuning the powerband. I've seen 1,500rpm gains using a .46 muffler on a .30 engine even with modest 155* exhaust timing. No argument - open faced exhaust is LOUD.

blw

My Feedback: (3)

The AMA doesn't have standards, do they? They recommend and clubs may adopt part or all, right? I would be more thoughtful about running the engine in the neighborhood here.

wcmorrison

My Feedback: (2)

I suppose you are right. OSHA does have standards and every club I belonged to has had sound limits of 85 db @ 3 feet as the max. Give the amount of noise damage that occurs, it would seem to me that AMA would have an established limit or a standard if you will. I know at one club we had to run off a fellow that insisted on running engines without sound suppression. He got angry and left in a huff. But it was in our by-laws and we applied that standard.

I wear hearing aids and in my past life was a Certified Safety Professional where OSHA ruled the roost. I realize our clubs and fields are not work places, and thus may be said not to be required to do anything. However, I would not let my club take such a risk, we already have enough risk to deal with.

wcmorrison

My Feedback: (2)

I have just spoke with AMA, they do not have a noise standard. They do encourage the use of a muffler. Again, there is nothing in their literature that says you have to have a muffler. He did say many clubs do have a noise standard and many have to fly under noise restrictions. So, yes, AMA does not have standard. But most clubs do have some form of noise abatement, e.g. must use a muffler or some sound measurement at a specific distance from the source or maybe measured at the boundary of the air field in which case the club can say they are meeting the civic requirements. I would refer you to the OSHA standards and if you exceed them, while not a work place, you may be challenged to meet those standards.

1QwkSport2.5r

I think bringing up OSHA in regard to model engines is rather moot. If someone's a jerk running without a muffler at a club field where noise restrictions are in place, then that member should face repercussions. That is, bigger engines that are designed to use a muffler. I'd not challenge someone running anything 1/4a or 1/2a. Anything larger should have some sort of muffling device in place as some engines are just stupid loud. Then again, even some muffled engines are stupid loud - I have a few of those myself.

Just my worthless 2 cents.

earlwb

Remember that if the OP has a area he can fly where noise is not a issue, then it isn't a problem.

blw

My Feedback: (3)

We fly out in the country in farmland. Our grass strip is part of a 600-ish plot of land, so it doesn't matter.

We had some people who wanted pilot stations, little fences at ankle level, etc and I looked up what the AMA says you have to have versus what they suggest. Big difference there and it is surprising what the AMA doesn't mandate. The suggested club layout, do not fly areas, etc are well thought out but they are only suggested.

Our club is very small, so we don't really have rules, etc. I wouldn't renew if we had OSHA rules or standards. Too many other wide open places to go fly the way you like if they ever did that.

Having said all of that, I know we are lucky. A lot of clubs have to have restrictions in order to stay in existence.

wcmorrison

My Feedback: (2)

I certainly understand your position flying out in the country. But keep in mind OSHA is regulatory law. Should some one claim hearing damage as a result you could be liable. And yes, some 1/2 A and below engines do not have mufflers and probably will not run with a muffler. But 1/2 A is fast disappearing, I do not think anyone makes 1/2 A engines anymore. There might be some little diesels and CO2 engines still being made but seeing them in use is rare now days.

1QwkSport2.5r

Unless someone is running a model engine sans muffler (or running an engine in any other manner for that matter) in or at your workplace, OSHA has no jurisdiction and will not enforce any regulatory law against a person or club where there is no employer/employee relationship. If a complaint is filed with OSHA in regard to model engine noise, they would refer you to contact a different state, federal, or local government agency.

Regardless if any engine/model class is losing popularity, there are still folks using these engines. Unless the club or location where these engines are used has a sound/noise regulation or ordinance in place, the 'victim' would have little recourse against said person or club unless the regulations or ordinances are being violated. In the event of a violation, it would be up to the club or local government agency to persue action against the violator.

It takes common sense - if you run your engines at your club and violate the noise regulations, it's up to the club to enforce the infraction. If you run engines on your property and violate local noise laws or bother your neighbors, the police would have to be involved and even if that were the case, likely there'd be a slap on the wrist unless one continually violates the regulations. At the end of the day, use common sense.

blw

My Feedback: (3)

Around here, that won't happen anyway as we still pretty much ignore a lot of the restrictions that take place. I would guess that mentioning OSHA would just cause laughs. I'm really serious and not poking fun. People just don't restrict things like burning, noise, gunfire, etc. Public prayer is commonplace and would shock some visitors. It's just a different mentality here and new restrictions take a long time to reach us, if they ever do. If it's too loud for neighbors we just say it's too loud, but mentioning OSHA would get you a lot of blank stares. Same goes for the workplace unless it's union construction, and I don't think there's too much of that.

A lot of people fly thinking they are under restrictions or laws by the AMA, and they actually aren't. This has a good side to it, and it has potential bad sides. We don't hear much about the AMA rule breaking, but it pops up from time to time and you would be surprised at what people say they do with models away from club jurisdictions.

Lomcevak Duck

My Feedback: (14)

You should not be concerned about OSHA interfering with model aviation. OSHA regulations apply ONLY to employers. OSHA regulations DO NOT apply to how much noise you generate in your hobby. I am a safety manager with a background in aviation and manufacturing. It is my job to keep people safe in noisy environments and comply with OSHA regulations every day. You would only need to concern yourself with OSHA if you were an employer and you were exposing your employees to the hazards of model engine operations. Even then, there are easy ways to reduce hazards, minimize risks, and comply with OSHA regulations, even if you are running an engine without a muffler.

Wear some safety glasses and ear plugs, and have fun running your .45F. I have an old OS .19 Steel Fin with an articulating baffle that is a hoot to run on a test stand.

blw

My Feedback: (3)

Hey Lomcevak Duck. Good to see you around again. Good points. I'm assuming you are talking about being around the aircraft there at Ft. Rucker.

Lomcevak Duck

My Feedback: (14)

Hey BLW, it's good to be back. I've been away from R/C for too long.

I had a busy couple of years- got married, had a kid, battled some health problems, changed jobs, moved three or four times, and all but left model aviation all together. I worked way too much, lost my building space, then lost a bunch of my planes to moving damage. If it hadn't been for my fascination with collecting OS engines, I might have left R/C completely. I'm slowly getting back into the hobby, but I don't post here much anymore.

No, I don't work at Fort Rucker. I hold a private pilot certificate and an A&P. I got most of my hands-on aviation experience working as a turbine overhaul mechanic and borescope inspector at Pratt & Whitney when I lived in Columbus. Now I work as Safety Manager at a manufacturing facility just outside of Dothan.

wcmorrison

My Feedback: (2)

Lomcevak, I am a retired CSP. I am simply pointing out that there are noise standards. They were not created by OSHA, they were developed by the medicos involved with hearing. DOD is also not subject to OSHA but they use the standards. And even so, the Air Force and Navy are rife with personnel that having hearing losses due to their personal abuse (failure to use ear protectors and plugs). Unfortunately, I am one of those that uses hearing aids. Use the standards as you like. However, making statements regarding OSHA may make you a Safety person liable. Think about it. I quit flying with a club because their field was located adjacent to a producing gas well, indeed it is located in the midst of their parking lot. Somebody has already back into the well head and knocked of the feed line. The rupture valve worked and fortunately gas was not spewing all over the place. I quit because as the former club safety officer and my past as a CSP puts me in a liability situation. So I do not fly there at all. Yes, they are not subject to OSHA either, but a slicky lawyer could care less and go after you any way. So I hope you have proper liability insurance to cover you.

1QwkSport2.5r

Let's petition the few model engine manufacturers that are left that still actually make engines to put a "common sense warning" on their boxes and in large bold print in the manual that running model engines may cause hearing damage. Add that to the area where they caution about not running engines near other people in the event someone sticks their fingers in the prop arc of if the prop isn't properly fastened and can come flying off, or model engines can cause burns, or the fuel is poisonous, etc.

Come on, it's all about using common sense (and common courtesy if others are nearby) and not being an idiot. If someone runs an engine sans muffler without hearing protection, they're idiots and deserve the possible hearing damage that may result. That has nothing to do with any safety standards other than if you violate noise regulations at your club field or in your city, county, etc.

For the record, I always run my engines with hearing protection if on the bench; muffler or not.

a70eliminator

I remember as a child my dad and brothers flying u-control, none of those engines ever had a muffler, dad made a diverter cut from an old quaker state oil can wired to the motor just to keep oil out of the fuse.
Harley Davidsons, race cars, gun ranges, rock concerts, fireworks, lots of fun things we do for recreation make noise, model planes included, heck my leaf blower and lawnmower makes just as much noise. I'm out in the county so noise is moot to me.

init4fun

With all the talk of OSHA and AMA sound regs I thought it may be prudent to point out that the gent sounded like he was looking for a brief test run in an area where noise would be no problem , to see if the engine is worth buying a muffler for . I don't think from his post he was talking about any kinds of extended running without the missing muffler , so I highly doubt any OSHA involvement will be required ......

blw

My Feedback: (3)

Yeah, I guess everybody thinks Rucker when you mention Enterprise though. I figured you may work for who is contracting the maintenance at Ft. Rucker now. I'm a retired Army pilot but I loved turbines the most. I tried earplugs only a couple of times, but you can't hear the compressor section while wearing them. I flew nights and we were having a lot of engine failures back then, so hearing every little noise could be a life saver. My hearing tested at the top of the charts when I retired. Sorry to hear about your health problems, and the moving damage. Hope you are doing better. I have a friend who is an A&P with the Army contractor in Dothan. He is the best r/c pilot I've ever seen. A short guy named Daniel.

earlwb

I remember as a kid growing up near Luke AFB in Arizona. We lived a couple of miles away from the base. Whenever they tested a jet engine they had rebuilt or repaired, and went full throttle. That engine was loud enough to cause problems with us watching TV inside our home. The engines were mostly from the F104's I assume, as that was primarily what they were flying there at the time.

But when I was older I flew many a model engine powered plane with no muffler. Heck they didn't even make mufflers yet. But yes the big engines were deafeningly loud.
At the time no one really thought about hearing loss or noise protection. It is a good thing such thoughts now come up though, as maybe fewer people will have hearing problems when they get older.

I also remember doing a lot of hunting and target shooting sans hearing protection too. That was more than likely a bad thing to do without hearing protection too.

aspeed

We still run control line planes with no mufflers at most fields that allow it. They work fine, better really. I always have a ringing in my ears from TD .049's and old Rossi's, not to mention loud music at the strip joints. The ringings never stops, but you only notice it when it is a quiet room. Even at work it was loud with earplugs, because you had to take them out to listen to people with the machines running. I wear earplugs even with mufflers when running them at home. At the field if you let go quick it is no problem for the ears.(neighbors maybe) I am finding the big 40% size motors are getting more irritating to me now, most people don't like the higher revving stuff.

GallopingGhostler

There's a large difference in noise output from an 049 sized engine versus a 60 sized engine. It has to do with the size of the explosion (combustion) coming from the engine. This is why the 60 engine's sound will travel further, and the noise unmuffled definitely hurts the ears. Control line, we run the old traditional 35 sized engines without mufflers, but they do not make as much noise (size of the combustion "pop" IYKWIM).

Some clubs in the country side allow engines unmuffled to .10 size. Above that requires mufflers. The 049's run best unmuffled especially the reed valve ones and older ones like the GIlbets, OK Cubs, etc. because they are limited in power to begin with. One needs adequate power to haul an 049 plane which tends to be somewhat marginal with those powerplants to begin with and need the power.

I'll run the 15's unmuffled on CL, but put a lesser restrictive muffler on an RC aircraft. I've got two OS Max 10R/C's, these are really sweet engines with only a throttle restrictor plate over the exhaust ganged to the carburetor. At full throttle with baffle wide open, they are as loud as an unmuffled reed valve 049. At half and lower throttle with baffle partly or fully closed, they sound muffled. At 3 ounces they are only a touch heavier than a Cox Black Widow, and really liven up a half-A plane, hence why I like them.

1QwkSport2.5r

Good to see you around George. Seems to have been awhile!

I run everything RC and most all of my engines have mufflers and I indeed use them personally. I occasionally run open exhaust to compare a given muffler for tuning purposes only, really. The last one I ran without a muffler was my Enya SS30 lapped engine. Enya stock 154 muffler versus open exhaust to compare exhaust/power restriction. Lapped engines seem to have more of a bark than a bang it seems. A ringed .29 had more of a higher pitched 'pop' which seemed more damning than the lapped bark.

I do agree on the really little engines not being *real* noisy, but if you run them on diesel fuel with a diesel head, they're even quieter. I think my buddy ran an OS .10 FSR he had laying around (zero to very little run time) that he had a diesel head for and noted when running it in at WOT, you could hold a conversation at normal voice levels with that engine running in the garage. That was with a muffler on it I think, though.