BT Sniper

Ok guys almost got my project figured out. Going to purchas the DA 100L and need to run it as quiet as possible when it is in the air. I'll have power to spare so any decrease at the sake of quieter operation is acceptable. Have heard the DA stock mufflers are pretty noisy. The only other refernce I can find reguarding quite mufflers is the standard Zenoah mufflers. Don't know what mufflers will fit the DA 100 so any advise or recamendations would be great. I figure on spinning a Belila 3 blade 24x12 or 25x12, any other props I should consider for quiet operation.

Not flying comp aerobatics here just a big plane straight and level. Here is another question for you all. With quiet being the concern would the exhaust mounted so it exits upward away from us on the ground make a difference? If so can the DA 100 be installed upside down so the carb would be on top and still expect the same operation of the engine?

Thanks guys the sight has been very helpfull,

Brian

P.S. is a kill switch necessary on the DA engines?

soarrich

My Feedback: (98)

Yes, it will run inverted.
It will be more prone to flooding during start mounted inverted.
Use canisters for the exhaust.
Muffle the carburetor intake also.
Use a Kevlar cowl, rather than CF.
Boat catalogs have a sound deaden lead/foam sheet that you can put inside the cowl for more noise reduction.
Don't hang your control surface control linkages out in the breeze, and seal panels together.
Seal control surfaces.

Pelle Gris

An Engel Super Silence 25x12 3-blade prop will help quite a lot on the noiselevel also.

Tired Old Man

My Feedback: (1)

Cannisters, tuned pipes, and 3 blade props ae the most effective methods of quieting an engine.

Where are you flying in Hood River? I'm aware of two local spots just outside of town. The other closest is at Dallesport but it does not have noise issues that I'm aware of. I'm up that way (Bingen) all the time for work and should be back there in another week or so. Send a pm and perhaps we could get together.

jedijody

My Feedback: (1)

I have read Snipers other posts and looked at the project he claims he has been hired to build for another company, along the lines of a UAV/UAS. I don't like to be negative but the whole thing sounds kind of fishy to to me. I know the model that he refers to well, with what he has proposed, it would never fly.

ampeater

My Feedback: (1)

Well, it's pretty common knowledge that the three major contribuotrs to engine noise are exhaust, tip speed, and the carburetor. Sounds like you have the muffler and prop taken care of. Now you just need to cut the flow of air to the carb and you'll be set....

Sorry, couldn't resist

Tired Old Man

My Feedback: (1)

There's a big uav company in his area. Interesting if he's working for them, but it's probable I would have heard of it.

Tired Old Man

My Feedback: (1)

Jody,

Where were the other posts?

I would have added this to the last but the moderators still won't permit me to edit. That is getting old, childish, and appears intended to irritate. 9-1 they edit this themselves to delete the criticism.

bjor

I'm running the same combo and need the same answers. Is it possible to just use your throttle travel adjust to limit the WOT to a point that gives you enough power for what you need - and a bit extra if required. I can use my throttle to reduce the engine RPM, but I'm asking becasue we have db measurements that are taken to determine an acceptable noise level at WOT from a certain distance, so if the engine is "restricted" it should give a quieter reading - both on the ground at in the air.

soarrich

My Feedback: (98)

Oh, yes pointing the exhaust up will quite it to a ground observer.

yarom

My Feedback: (82)

Two canister (MTW 75) and a 3 blade prop (25x12 or 26x12).

It is so quiet I can hardly hear my engine when a trainer flies nearby. Don't hear a thing when low throttle.

I also have a DA-100 with just the 3 blade prop and that diminishes the noise quite a lot...

pcsol

My Feedback: (2)

I believe you mean Biela ? The Biela 25/12 are very quiet, but IMO Fuchs 25/12 are a touch quieter still. If performance truly isnt an issue you could prop up to the 26 inchers once you have some time on the engine.
As in Yarom's case, I get drowned out by little.40's all day long (Im also packing MTW's).

Tired Old Man

My Feedback: (1)

BT,

I'm curious as to which of the two UAV companies in your area you're building a plane for. Cloud Cap or Insitu? They're the only legitimate unmanned companies in your area and I know neither one of them needs outside help in building a plane.

Eagleburger

Put it in a bag. Mine is quieter than a mouse.