The problem with the auger muffler is that everyone said it sounded like a flying weed-eater. It was sometimes described as a flying chainsaw. Not the most flattering description. It wasn't "that" loud, but you could definitely hear me coming from miles out. Maybe that's a good thing?
I guess we'll soon find out what the HP-2 sounds like with no packing.
Mark
On 1/14/08, bmears9413@aol.com <bmears9413@aol.com> wrote:
Mark,
I thought your spiral muffler you built was quiet. Did it turn out to be too loud after you got in the air? Or too much back pressure?
Bob Mears
-----Original Message-----
From: Mark Steitle <msteitle@gmail.com>
To: Rotary motors in aircraft <
flyrotary@lancaironline.net>
Sent: Mon, 14 Jan 2008 9:12 am
Subject: [FlyRotary] Re: Drips? was [FlyRotary] Re: URL for HushPower
Ed,
I don't think it was doing this until after shutdown. That makes sense as all the heat builds with no airflow over the muffler. It would probably be wise to put a SS heat shield between the muffler and the fuselage floor. (I had a piece of Zetex installed, but hadn't waited long enough for the RTV to cure and it started coming off during flight. I will try a fresh piece, and wait a little longer this time.
You're probably right on 1 though 4. I suspect the packing material to be fiberglass. I doubt that ceramic would melt that easily.
Mark
Packing, I don't need no stink'in packing!
On 1/14/08, Ed Anderson <eanderson@carolina.rr.com
> wrote:
Hi Mark, interesting development. I suspect several reasons you may be the only one to notice.
1. It might be that the 3 rotor keeps the average muffler heat level higher as you have (approx 1/3 more heat energy with the third pulse during the same time interval).
2. Your muffler is pretty close to the exhaust port - less chance to lose heat before the muffler
3. Your muffler is pointed down (mine and I suspect most are more/less horizontal) and therefore provided an easy path for the melted packing to drip down.
4. What does the packing seem like? I would have expected glass or ceramic packing - but, a glass packing would be the more likely of the two to melt.
If this is the insulation packing and it goes, then the shell might get a bit hotter.
----- Original Message -----
Sent: Saturday, January 12, 2008 5:58 PM
Subject: [FlyRotary] Re: URL for HushPower
For rotorheads that are contemplating using (also the mildly curious) the Flowmaster HP-2 "resonator" muffler,
I installed the HP-2 today on my 20B and was able to do a run-up. Bobby Hughes and I both agree that the exhaust tone is much, much mellower with a deeper tone. My Lighspeed ANR headset had no problem cancelling out this low-frequency exhaust tone. While the overall sound level was still pretty significant, the exhaust tone was much more pleasant to the ears. The ear-piercing, glass shattering, nails-on-the-chalkboard, make-you-bleed-from-the-ears, exhaust tone is totally tamed. The 3-blade M/T prop is the primary noisemaker now. The test took place between two rows of hangars, so I feel that DB readings are not very realistic. I'll take those again out on the ramp and post the numbers. If the HP-2 holds up to the pounding of the rotary's exhaust, I'll be a very happy camper.
Mark S.
On Jan 12, 2008 3:22 PM, Ed Anderson < eanderson@carolina.rr.com> wrote:
They are both used stock Rx-7 turbos. one is the older model pre 89 and the second is a later model 91 year. They both appear to be in working condition in no nicks on the blades and they spin. I used compressed air to spin the compressor wheels to they were really whizzing along.
One came with my 91 turbo block and the other was given to me.
Ed
----- Original Message -----
Sent: Saturday, January 12, 2008 3:46 PM
Subject: [FlyRotary] Re: URL for HushPower
Well,
then we just have to keep on looking for a "justification" for you/your area/etc. :)
Just wait, I'll find something! :)
Thomas
How about: ".....
I have two turbo sitting in my shop......."
...are they new/used? What's the scoop on them?
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