Mufflers or not

I'm getting ready to order an exhaust for my kit and I have found that most planes run a straight exhaust. I'm curious as to how loud an umuffled system is and if there is a major reason that most planes are flown without them. I understand there is a cost and weight penalty, but I would think a quieter plane would be more pleasant to fly and would be a better neighbor at the take off end off the runway. I'm also looking for input as to which system is the best all around. I know the vetterman is the most popular but I have seen other systems advertised. Any input appreciated. Bob Collins (the other Bob Collins)

Do NOT install Supertraps.!!!

Do not intall Supertraps!! These are automotive racing mufflers.... I tried two of them on my Vetterman crossover several years ago..... Within 10 hours the glass packing plugged the discs/louvers at the outlet. NOT GOOD!!! They were very quiet the first few hours then plugged up at the Disc/Outlet..... DO NOT INTSTALL THEM. Just a warning. Any muffler with glass packing is going to burn the glass out in time because of the High EGT's. Find a muffler that has baffling without glass in it. I even tried Borla's, forget about them, they lasted 5 hours....Best thing I've found is turn the exhaust outlet down away from the belly of the airplane. This only helps with the person in command flying the airplane but not on the ground. Sorry I didn't help in this area other than things to avoid or try. Been there done it..

Bob,

A month ago I called Larry V. to ask him a few questions regarding my O-290 installation. During the conversation he mentioned that all his new exhaust systems include an additional fitting aft of the swivel to allow for the installation of a muffler. He went on to say the average airplane looses around 3 hp with the installation of a muffler. This small number could be lost in rounding so after hearing that I see no reason why you wouldn't want to install them.

FYI, I have an "older" exhaust which does not have these fittings, thus I will run straight pipes and turn up the ANR.

I'm one of those neighbors at the end of the runway. Well actually off to the side, but right under the pattern, base or crosswind.

I'd be quite disappointed to have mufflers stuck on the Lyc's, as I really enjoy the sound!

Now, if it's a high rev subie or rotary, then perhaps mufflers should be required!

L.Adamson RV6A 180HP Lyc

My exhaust was a pre muffler Vetterman. If I was building now, I'd definitely go with the muffler.

With airports being closed across the country, it is important to try and be a good neighbor.

Be nice

kevinh said:

My exhaust was a pre muffler Vetterman. If I was building now, I'd definitely go with the muffler.

With airports being closed across the country, it is important to try and be a good neighbor.

Click to expand...

Cessnas have "mufflers" and they are noisy as ****. The down side of Cessnas are they are slow and people on the ground hear them a lot longer. RV's move so fast the source goes by faster and the perceived noise is less. I know. I sit under a path with cessnas and RV's cruising by at low altitude. The cessna drone goes on and on. The RV just goes so fast you hear "pu put puT PUT Put put ut.....", than a spec on the horizon and no sound. It does not last long. (please no low level acro over the elementary, muffler or not, )

I can not argue with kevin, I like the way he thinks, be noise conscience. However I would say the RV's really climb very well and get above the ground fast, plus you can choose the way, where and when you fly over people, places and things. Some people will complaining if a glider flys over.

With that said I would skip the Muffs if the weight is high and the noise suppression is not significant.

I can't imagine they are super silencers by their size. A muffler's ability to suppress noise is usually proportional to it's size, weight and loss of engine performance (back pressure). Like I said have you heard any airplane that was really quite with a muffler? (cessna, piper, beech...)

I have no intimate knowledge of Vetterman's product, but if there are greater cost, weight and heat under the cowl than straight pipes, I would pass.

However thinking positive, if it really lowers the old Dee-Bees (noise), it would be worth it. You got to research it. Vetterman should do a controlled test with a dB meter, with and without muffler. If it does not make a big difference you are carrying dead weight around. Also they are bigger units that take room up under the cowl and may add more heat under the cowl since mufflers tend to get hot and it has more surface area than straight pipes.

Here is a HOT TIP (pun intended)

Piccolo tip -OR- Piccolo bent tip They don't cost, weigh much or add much heat under the cowl. No it will not be stealth but does make a slight but noticeable level change (3 dB)** and tone, I have been told.

** claimed, but no comment how it was measured, take off power etc.

I have thought of a swiss muffler, but the external drag would cost some speed. In Switzerland they have strict noise control and homebuilts use long external "glass pak" pipes, but they do work, and could make one. Even though it's visable and undoubtedly cost some speed it's effective as I understand it.

Here is an excellent article which address everything I touched on:

http://www.piteraq.dk/flight/muffler.html
http://www.piteraq.dk/flight/exhaust.html

Cheers

check RVator

If my memory is correct, there was an article in the RVator in the last year about flight testing various exhaust systems in the -10.

IF I recall correctly, dual muff system was best.

Mike

Fosling exhaust

Hi, Bob / rvator9a, John Forsling with Forsling Aviation sells the "Piccolo Tips" that George showed a picture of if your interested. His phone number is 303-903-3290