BaldEagel

I have a 45mag fitted with a BCM wrap around pitts style silencer and the noise level is horendous, Pe has suggested a few alternatives which I will try and report back on with my subjective ear, I do not have a db meter so it will be an in my opinion this has a nicer tone and/or quieter noise than this type report and will be compared to some of my other engines, meanwhile is any one out there prepared to stick there neck out on the 58Prosport noise level, as mine comes back with the new crank next week and I need to know what silencer to get.

Mike

pe reivers

For the 58cc engine in inverted intallation, I can suggest a MTW TD110 or 110K canister and "type 3" 28mm swan neck set, or equivalents. Leave the header at 30cm length or slightly longer for a 24x10 prop.
For rpm measurements with this setup, look at http://www.prme.nl/forum/viewtopic.php?t=54

BaldEagel

Pe

Thanks for that, I have a 22x10 3 blade that I plan to put on the 58pro so the reccomendation looks to be the one I need, I will have a small problem in fitting it all in too the QQ Yak, but nothing that cannot be got over with a bit of fettling, cutting and rebuilding to put in a cannistor tunnel, perhaps I need a bigger drop to put the cannistor under the fus instead of through it as the UC is quite low on the underside, can I get a bigger drop on the manifold?

Mike

pe reivers

with the type3 set you can get almost any drop if needed.

BaldEagel

Oh goody, will do some measuring and let you know what I need.

Mike

BaldEagel

I have now ordered the MTW 75 with the manifold and peripherals for the 45mag and will be installing it on my Edge 540, this will take some work as there is no provision for a cannistor muffler, if anyone is interested I will detail this installation on the Giant RC Aircraft Thread, meanwhile I will post the noise or lack of I hope on here soon as it arrives and is fitted.

Mike

pe reivers

Just post a link to that thread here. No use in cross-posting.
I have a hard time getting the 45cc engine to comply with our 80 dB(A) at 7 meters. TD75, 3W 21x11.
Had to fit a smaller carb, made internal fuselage carb mufflers, modified the TD75, and still have to do some to get rid of those last 2 dB. In the end, it is prop noise that rules.

BaldEagel

OK Pe will do:

Canister installation details are on http://www.rcuniverse.com/forum/m_4818397/tm.htm in the Giant RC Aircraft Forum.

What mods did you do to the TD75?

Mike

BaldEagel

Pe

What is the minimum reccomended length of the manifold for the TD75? I will be using a 22x10 to run it in on and then a 21x10 from then on, unless you tell me otherwise. I have looked on your site and I am a little confused with your results as you say the header length for a 21x10 on the TD75K is 25cm, the header you have supplied to me is only 23cm, have you included the length of the muffler in the dimentions and not just the header?

Mike

pe reivers

Mike,
The swan neck I sent you has 38cm length, measured along the centerline. length at start of straight section is already 20 cm.
Use the smaller prop for running in. Then switch to the larger prop.

BaldEagel

Pe

OK a bit of brain fade there on my part, its what comes of using a scale rule instead of a full size one. the header length is working out too 28cm fixed because of UC and former locations, will use the 21x10 to run in on and will vidio the results and do a comparison with the Pitts muffler. Should be the middle of next week sometime.

Mike

pe reivers

28cm is a good length for very stable engine operation and throttle response to tuning of the walbro.

BaldEagel

Pe

Thanks for that, thought I would show the installation on here as well as in the installation thread just to show how I have done it. Should be able to test the systems against each other within the next two days.

Mike

pe reivers

I taper-pinched the stinger outlet, and drilled small holes in the taper.
This was not enough, so I now have the TD90 fitted. Combined with a smaller carb and the internal header pipe pinched to 50% flow area I am at 78dB(A). (3W 21x11 prop at 5800 rpm) I may with this setup increase carb diameter again to increase rpm, and make use of our 80dB(A) limit.

BaldEagel

Pe

Now that is interesting, how much difference did it make compared to the TD90 you know have fitted?

Mike

pe reivers

This is the TD90 I now have fitted. With the original, non-pinched version, it turned about 5900 - 6000 rpm, (with pinched stinger and 26cc carb). With non-pinched stinger, rpm was a stable 6000. Due to the pinched stinger. the rpm was not stable though, and it produced 81-82 dB(A). To stabilize rpm, I hade to open up the H needle which resulted in .... 5800 rpm.
With the pinched inner tube, rpm ranges from 5800 to 5820, and is very stable with a slightly pale plug color. Both needles had to be opened up slightly, low end idle burbling stops at 1/4 throttle.

BaldEagel

Pe

Completed the installation of the cannister, what I can't belive is the 1050rpm increase between the two silencers, the cannister is a much more muted sound with a much cleaner pick up from low revs this is a revelation. See movie.Click here to watch MVVS-45-Mag-with-Pitts-and-Cannister

Mike

pe reivers

I am glad you too are convinced, that Pitts mufflers realy are no good for gas two strokes. You would also be surprised at the temperature difference in the running engine. My TD90 system has better throttle response though.
Even better are the new 4-chamber canisters that MTW is working on. 200 rpm gain over the 3-chamber mufflers, and MUTE like my pinched header with 100 rpm loss.
I had a chance to test one very briefly before I had to pass it on. Tonal characteristic much like the very much larger, heavy and well muffled JMB. Where the JMB tended to overheat the engine, the MTW was very easy to adjust the carb to, without the slightest rpm drop. All with outstanding throttle response. A stroke of genius, though the 4-chamber design will probably be a bit more expensive to produce.

BaldEagel

Pe

I know its early days, but I need something for my 58pro when will the 4 chamber one be available? and what size's will it be available in, I have got to put something in my QQ Yak that is accepatable as at the moment I don't think I can fly it at my site due to the excessive noise.

Mike

pe reivers

I think it will be available soon enough. Testing to the hilt first, then production.
At the moment I have no data, but everybody is enthousiastic.

BaldEagel

Let me know when they are available as I will have one for the 58.

Thanks
Mike shutting down.

BaldEagel

With a view to reducing the noise level even more I have installed the ISO mount on my Edge, pic shows the mount temp on the nose, note the thrust washers on the right hand mount and the ignition mount on the left.

Mike

pe reivers

Nice swan neck
check your mail for suggestions concerning the 58cc solution.

apostle

I'm building a CMPro EXTRA 330L 2m w/s. I'm thinking in powering the plane with the MVVS 45 MG IRS, as there is no room in this plane for the cannister can anyone out there pls advise a newcomer to gassers as to what is the best solution for an incowl inverted w/a. Has MVVS come up with one? Will the INVERTED W/A for the EVOLUTION 45 mg do for this engine?

pe reivers

The 3208S muffler is available now.