From: ntaib@silver.ucs.indiana.edu (Iskandar Taib)
Subject: Re: Quiet combat?
Organization: Indiana University
Distribution: rec.models.rc
Date: Sat, 2 Jan 1993 03:17:08 GMT

In article <1992Dec28.084042.2566@inland.com> bloom@inland.com writes:
>In article <Bzty7z.1n6@usenet.ucs.indiana.edu>, ntaib@silver.ucs.indiana.edu (Iskandar Taib) writes:

>> The big difference between Combat and other forms of model aviation is 
>> that the planes are expected to hit each other and Terra Firma rather
>> regularly. The good thing is our motors (the expensive part of the air-
>> plane) are pretty good at surviving mishaps such as these (though not 
>> 100% of the time!). Most feel that the addition of a muffler will not 
>> only cause weight problems (Fast Combat planes weigh about 18-21 oz, so 
>> a 3 oz muffler is quite an addition) but will be costly in a crash. 
>> Aside from losing the muffler the engine it is attached to might break.

>So where was it shown that a 25 oz plane will not fly?  If everyone is 
>required to use mufflers, then all the planes will become 3 oz heavier. 
>So what?  There are rules for engine displacement aren't there?  There 
>are many forms of racing e.g. motorcycles where minimum weights 
>are set by rules.  All that is needed is the stroke of a pen.  Once that 
>is done, I'm sure someone will start selling break-away mufflers, or 
>figure a way to put the muffler behind the cylinder, or develop flexible
>soft polymer mufflers.  It's only impossible until you get started.

Fast Combat planes already pull your arm off. A 25 oz. airplane will be 
pretty obnoxious out there if you get it doing 120 mph. 

Its definitely possible. The thing is someone has to start up a cottage 
industry making the things and there has to be some experimentation. One
possibility is carbon or glass tuned pipes but I can't see the things 
costing less than $50 apiece and they'd break rather easily. Paul Baluch
has been playing with the things - you make them out of carbon sock mate-
rial. The main problem I forsee is attaching the things to the current 
motors we have. The Fox Combat Specials everyone uses are side exhaust 
and not only don't they have exhaust lugs they also don't have much of a
lip on the exhaust port. The muffler will also have to be out of the way 
when landing - on top of the wing, I suppose. New planes would also have
to be built, since the old ones will most likely balance too far forward 
with a muffler. Then we'd have to figure out a way to mount the engines 
vertically - quite a bit of an additional bother since the usual motor 
mounts and center block that everyone uses won't work. Then theres the 
question about how effective the things are in actually reducing noise. 
In California there used to be a group called WAM that ran Combat using 
.15s and mufflers (and very weird rules!). Last I'd heard, whenever WAM 
Combat was flown everyone just puts a silicone elbow on the motor. Not 
much of a muffler. I suspect the same thing will happen in Fast Combat 
if mufflers are required and not described in detail in the rules.

A stroke of the pen may be all it needs but it will annoy a heck of a lot
of people, especially if what is mandated doesn't work particularly well. 
A good example is the jet fuel required this past year (I think it was 
50-50 MEK and Methanol). Not many were able to get their jets started at
the Nats. Most will probably just start holding non-rulebook meets (very
common in Combat, eg. the various varieties of Super Slow). 

Mind you, I'm not against mufflers per se, just that I'd like to see 
something working and reasonable price-wise (considering its short life) 
and a few test meets before anyone starts mandating them. 


-- 
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Iskandar Taib                          | The only thing worse than Peach ala
Internet: NTAIB@SILVER.UCS.INDIANA.EDU |    Frog is Frog ala Peach
Bitnet:   NTAIB@IUBACS                 !
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