ORIGINAL: cmoulder
ORIGINAL: MTK
ORIGINAL: tele1974
Most of that is air frame noise. I have the same bird and the thing is loud. I am working on quieting a few things down. Most of that noise is from the ball links on those big barn doors of ailerons.
I have soft mounted the SAP 180 in the EFXtra as shown in the thread for that plane. I believe I posted a bunch of photos on that. Much quieter set-up. Expect 3-6 dB delta on noise
But it is still louder than the Temptress (which is extremely quiet by gas standards!), no?
Do you think the increased noise with the Extra is due to the more voluminous fuse and cowl (and wings, perhaps) and the open structure design? All else being equal - with the engine, mount and exhaust - what else could it be?
Actually, no that much!! Temptress and Extra equipped with same prop compare favorably to one another. Extra's advantage is that the pipe is fully enclosed, surrounded with dead balsa. Extra's disadvantage is wood and film resonance. Overall, noise is about a wash between the two airframes in the air.
Temptress is about as quiet with the SAP as with the Webra 160 after considerable work to get her there....not quite but very close. A fully enclosed tunnel with dead foam lining would quiet the set-up even more,,, but the same would be true of a glow set-up. What we are fighting is the considerable increase in exhaust temp compared to glow. Hot reports are louder than cooler reports.
If we want more quiet, we need to cool the pipe (exhaust gas) more effectively. That's not a trivial thing.....a much closer fitting shroud surrounding the pipe would help but adds weight. Can't really make it out of depron because it would eventually melt from the gasoline. Glass is heavy and so is carbon...and expensive. Soft balsa would help but also adds weight. Soft balsa shroud is probably the best bet.
On the other hand, I have a pretty quiet set-up already so I am not inclined to investigate much further. If something makes sense in the process of assembly then I will incorporate it.
The set-up shown in the video is very loud compared to pattern set-ups but that's a requirement for the type of flying it is intended for. It's a show plane....spectators are attracted to loud.