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Author Topic: Exhaust pipe?  (Read 1563 times)

Offline Ken Deboy

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Exhaust pipe?
« on: May 17, 2007, 07:41:02 AM »
I'm thinking about routing the exhaust through a piece of tubing from the muffler outlet to the tail of my plane. Does anyone have experience with this? Will it hurt the engine? Cause it to run too hot? How much will power be affected?

thanks,
Ken
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Offline Jim Oliver

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Re: Exhaust pipe?
« Reply #1 on: May 17, 2007, 08:11:47 AM »
Hi Ken,

I have seen some of the RC guys run a piece of plastic tubing from muffler outlet down the outside of the model for 10-12 inches.  The tubing was actually pushed onto the muffler outlet, so the I.D. was not great;  really reduced the sound of the exhaust a lot.  Don't have any numbers but there was a significant power loss, too. 

If the exhaust from the muffler were introduced into a tube of somewhat larger diameter that the muffler outlet, with some provision for good airflow through the tube, it might work.  One possible problem might be that the tube could cause an "untimed" pressure wave to return to the muffler outlet; sort of an "untuned pipe".

Simple solutiuon to the oily model problem: buy another roll of towels!! (Or go electric?? VD~)

Jim
   
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Offline Jim Thomerson

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Re: Exhaust pipe?
« Reply #2 on: May 17, 2007, 09:28:33 AM »
A tube all the way to the tail is said to work fine on diesels.  Not tried it myself. 

Online RandySmith

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Re: Exhaust pipe?
« Reply #3 on: May 17, 2007, 10:31:08 AM »
I'm thinking about routing the exhaust through a piece of tubing from the muffler outlet to the tail of my plane. Does anyone have experience with this? Will it hurt the engine? Cause it to run too hot? How much will power be affected?

thanks,
Ken

Hi Ken

That will cause a lot of heat and back pressure, that has been tried before with "not so good  results"
Windy used that in one of his ships back in the early 90s, I tried it attached to the exhaust of pipes, it killed off power and made the engine run very hot
If you do it make sure you use a large diameter tube, maybe at least 3/4 to 1 inch

Randy

Offline Larry Wong

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Re: Exhaust pipe?
« Reply #4 on: May 18, 2007, 08:32:08 PM »
I used a long carbon fiber tail pipe on an O S  46 R/C plane and it work fine. ( BUT ) it had a Davis Diesel  conversion.  y1 y1 y1 #^ #^ #^
Larry

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Offline L0U CRANE

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Re: Exhaust pipe?
« Reply #5 on: May 21, 2007, 12:03:59 AM »
Ken,

If you're using a chip (tongue?) muffler, you're pretty well committed to some exhaust oil mess. I guess the best answer in that case is learn to live with it.

If you'll use an OEM muffler or pipe setup, you could add one of those curved exhaust extensions aiming the juice away from the model. Many do and I haven't heard of a drastic power loss from it.

If you have, say, a jet-style model and think it would be kewl to have the exhaust - apparently - come out where it would from a jet engine, a much larger diameter tube MIGHT not cut power a whole lot. As Jim T points out, this doesn't trouble diesels much. Glows, however, are more sensitive about it.

Let us know what you choose, and how it works?
\BEST\LOU

Offline M Spencer

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Re: Exhaust pipe?
« Reply #6 on: May 21, 2007, 01:18:50 AM »


  full size practise is to use 'oversize' pipes for Max. RPM output.

 Smaller dia. pipes to maintain gas speed for torque ,say on a rally car.

 Possibly an 'Augmenter " feed arangement as per Al Rabes Mustang.

 the header feeding into a flared oversize tailpipe. effectivly making that a seperate system.

 Cant be too much trouble to set up your 'test' system on the bench,

 or a plank of say 10 x 1 timber, to test attitude reaction.

(whilst keeping your face well clear of the prop.Maybe some safty googles ! )

 More prattle ; the old 'hot rod ' bible refers to 'tuned lengths ' - wave cycle.
 on a metal Ex. pipe ,running a bead of paint down the pipe,
it burs of at the Tuned Lengths, note plural . So, youd fit the resonator at say the third
Hot Spot , to keep Ex. Gas  temp (and speed ) up, then pipe to muffler,probly using the paint trick again.

The Resonator ,is a straight thru Glass Pack heat chamber, which effectively
holds the front section at working temperature ,

Any car / M-cycle is a pig to drive on the gravel with an oversize system,
as it has baulky throttle responce (pick up )below say half revs.
which means you have to go really fast . . . .

Maybe pick up a pile of different size off-cuts from a workshop,
or retail Alloy tubes not expensive in smaller sizes,
so armed with a notebook, you can use a few ? hours finding what works were your aiming.

A guess is a Mini pipe feeding into the Exhaust at the bulkhead behind the fuel tank .

And dont let the 'test plank' get all oily , the old tin of grits for hand grip Trick ?& a good rag or 3.

Offline CharlesF

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Re: Exhaust pipe?
« Reply #7 on: June 10, 2007, 12:32:31 PM »
Funny, I was going to suggest the "augmenter tube" (as used with Jetex) as Matthew did.

I think a 19mm (3/4") tube open at the front end where the muffler goes in should work well.

One of the RC (ex-C/L) guys at the club today took the long silicone tube off the muffler on his plane. It was louder, but he says the performance was much improved.

But the tube with the open front end should guide the gunk out the back without slowing / heating the engine with back pressure, and the venturi effect should stop the gunk coming out the front

Charles

Offline Douglas Babb

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Re: Exhaust pipe?
« Reply #8 on: June 10, 2007, 01:08:59 PM »
If you think it through an augmentor tube can be used to help cool the engine by drawing air through a properly designed cowling. Food for thought. H^^

Dave Adamisin

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Re: Exhaust pipe?
« Reply #9 on: June 27, 2007, 09:48:05 AM »
The "augmentor" pipe idea was used back in the sixties by Ron Adams in his Intruder stunter. It worked very well with no large scale effects. Being a jet model he ran it out in the correct place and it had a nice effect of producing "exhaust" at the correct position.

Offline Bradley Walker

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Re: Exhaust pipe?
« Reply #10 on: June 27, 2007, 11:07:32 AM »
A $5.00 silicone exhaust diverter is cheaper, easier, and lighter.
"The reasonable man adapts himself to his environment. The unreasonable man adapts his environment to himself, therefore all progress is made by unreasonable men."
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Offline Bill Little

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Re: Exhaust pipe?
« Reply #11 on: June 28, 2007, 08:17:04 AM »
The "augmentor" pipe idea was used back in the sixties by Ron Adams in his Intruder stunter. It worked very well with no large scale effects. Being a jet model he ran it out in the correct place and it had a nice effect of producing "exhaust" at the correct position.

Hi Dave,

Welcome to another member of the Adamisin clan!  Glad to have you aboard. y1

I have often heard of Ron's Intruder, but I have never seen a picture of it. (??)   I wonder if plans were ever drawn.........  The Intruder is one of my all time favorite airplanes!

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Dave Adamisin

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Re: Exhaust pipe?
« Reply #12 on: June 28, 2007, 05:43:19 PM »
Thanks Bill. I've been looking forward to climbing abord. Ron did an article in one of the Model mags back then so the plans "should" be available somewhere. I personally loved his his intruder. It had a full round fuselage and many very nice scale details. A fine effort. My dad did an adaptor to turn the Tigre 46 into a rear exhaust and Ron ran it down an insulated aluminum pipe that was around .750 OD. It was an unusual sound for the time as very few people ran mufflers yet.

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