Control Lines For all you fly-by-wire fanatics!

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Old 04-15-2012, 06:56 AM
  #1
Boeing727
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Does anyone have a fairly realistic opinion on the effectiveness of

tongue mufflers ? Do they quiet an engine up to .40 or is it just politically correct !!!
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Old 04-15-2012, 09:20 AM
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Quote:
ORIGINAL: Boeing727

Does anyone have a fairly realistic opinion on the effectiveness of

tongue mufflers ? Do they quiet an engine up to .40 or is it just politically correct !!!
GOOD POINT there Boeing727! IMO, having used several, I tend to believe the short "Tongue Muffler" is simply an Exhaust Director. The long ones may
provide some noise reduction but not much. They do provide enough back pressure to provide some tank pressure if so desired.
Many flying facilities do require a "muffler". The tongue fills that requirement I suppose. It also looks better than a big muffler hanging on the machine, especially certain models that are rather less pretty when a big muffler is hanging out. This being CL, I guess you are doing it on CL models. Should be fine there and less weight up front, plus looking much better.

I still like that "politically correct". Also the name, "Boeing727". Almost 2/3 of my time during my 28 years airline was spent in that machine. Warmed all 3 seats as time went by. [8D]
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Old 04-18-2012, 04:05 PM
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Lou Crane
 
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Default RE: muffler

As Hoss said, they are more cosmetic than effective at reducing the noise...

However, they DO cut the noise down some, and considering the low altitudes CL models use, the noise "footprint" is much less than for a similarly powered RC model at 200' or more.
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Old 04-18-2012, 08:00 PM
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Default RE: muffler

My gut feeling, based on nothing other than intuition, is that they cut down power more than noise.

G
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Old 05-08-2012, 11:57 AM
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G,

Not refuting that tongue or chip mufflers may cost some BTTW top-end power potential. I prefer CLPA, where the problem is much more often restraining power output to a consistent, steady range well below peak, over several minutes flight time.

The (usually) more restrictive "chip" mufflers serve well to - as Hoss said - AIM the sound a bit so that it seems not quite as loud at reasonable distances, AND has side benefits in being a source of 'muffler' pressure for fuel feed, and in being very much lighter than any "serious" sound suppressor type muffler.

Maybe we can develop a BOSE-type noise cancellation gizmo to hang on our models? Well, no, not really. Limited eyesight groups are already seeking legislation or ordnances to require hybrid autos to have some form of noise maker so even the sightless can hear them coming or going. Can you imagine how careless ordinarily cautious people can get when they can't hear a 2kilo+ model plane screaming (silently) down at them at high speed? Who gets sued first?
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Old 05-08-2012, 05:01 PM
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Default RE: muffler

A hollow tongue with some restricted outlet does not do much for noise as the fellow have already stated but the Dubro Tongue muffler uses a removable baffle plate near the outlet and has a hole plug near one side on the end and this has a long coil spring inside that is removable.

The idea is to shorten or remove the spring to taylor the back pressure and/or noise, when the full length spring is used there is noticible quitening of the exhaust note.

I have used one on a fox stunt in more recent years but not currently as I only use throttled engines now. Also the dubro tongue muffler provides useful pressure for those of use who use bubbless tanks rather than a more conventional uniflow set up.

I no longer use my dubros since all my controlline engines now are throttled RC engines and I use mostly stock mufflers.

John
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Old 05-08-2012, 05:50 PM
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Hello John:

My apologies to the thread and to Mr. Boeing 727 as my question to YOU certainly upsets the thread, but you stated two things that really interest me.

1. Do you use bubbless tanks on CL Stunt models? Building a new one, first time in many years, and I am going with one of those as I have had great sucess in RC with them.
Any words of wisdom would be appreciated. Model is my own "design" [:-], and powering it with Evolution .60. Wing area is about 630 squares.

2. Big one! What advantage do you get with throttle engines in CL? That is if you are doing CL, or maybe you don't do stunt anymore? My last CL Stunt contest was around 1973 - 4 or so. I thought I still knew it all, but now I find I don't know poop anymore. []

Any pointer welcome. I will be watching for another thread if you wish. "Beginners" maybe [:-] [] [:'(]
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Old 05-08-2012, 10:38 PM
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Hey Hoss how ya doing, Yes I have been following the posts on your return to controlline and thats wonderful. Here is a vidio that explains why I only fly controlline with throttle anymore, I need to be able to control the length of my flights and land when I need to and not wait to run out of fuel. Also it is wonderful to shoot touch and goes to my hearts content if I want to and using an old three line system would be almost impossible for me to set up each time every trip to the field.

I have always kept a hand in to some degree and never really abandoned controlline for RC completely and when I went into the chair ten years ago I could I could not fly any more at my home (RC) field in the dirt with the chair and only could fly On concrete or pavement. The solution was to have a twenty foot concrete circle poured at my RC field, that along with my Bill Young over the wire electronic handle was the ticket and it was wonderful. Now with 2.4 my next ship will have an over the air 2.4 system and the transmitter (one of my old Prism 7's) will be worn on my chest with a strap system and the sticks pointing to the airplane. Its easy now to simply reach up with my free hand and do whatever with the throttle. This will greatly improve set ups and simplify things for me.

Yes I use mostly Tetra four ounce bubbless for the controlline airplanes because I get the most uniform and consistant runs with the RC engines on my controlline ships. I am using both OS .40 FP (the ship in the vidio) and OS .35AX in my Nobler.

I suppose its from my Pylon racing days but I am a firm belever in the bubbless tanks and even use them on certain problamatical RC airplanes. One example is my Quad Kaydet a four engine ship (.25AX) which I do perform some aerobatics with. Without the bubbless during certain rolling manuvers the outboards would always surge unpleasently. The change to bubbless tanks completely eliminated that somewhat unusual problem.



http://www.youtube.com/watch?v=GzZM8...2&feature=plcp


John

Will be looking forward to hearing of your continued adventures on your return
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Old 05-09-2012, 07:02 AM
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Default RE: muffler

Holey Smokes, John, you just need a few new airplanes! That stash is unbelievable! Just WOW!

I may not make Brodaks this year, but hopefully next year. Same as I said that a year ago. [] I have a hard time getting really into modeling
anymore. Can't understand it but the fire just ain't there like it used to be. OTOH, I had that same burnout in the mid '80s for about 4 years when
I went bass fishing for a while.
If this new stunter gets going, just maybe things will perk up. I have a scale job under construction and sitting just where I placed it almost a year ago.

I have an electric line set-up for scale. Do you use insulated lines in stunt? Never thought that would work.

Thanks for the reply and the video, again WOW!
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