Earthstar Forums

Well now I know much more about the Zulu's. The copy-cat airplane site guys tend to favor the Telex 50's for long stretches, and for my 1-2 hour flights I'm still using my old Dave Clarks. Years ago when I first bought the Clark's, I flew two times to Central California in my Cessna 150, and yes, the clamping pressure built up, (or so it felt), as I flew further south. Maybe if I can scratch up the bucks, it's time for an upgrade.

And cockpit noise, the other airplane site guys have been working this same problem, and it's not just the 2-strokes. Apparently with a Powerfin prop, and a straight exhaust 912 running at 5500rpm, there is a bucket of noise too. On my Gull 2000, I've crammed a 2" thick foam piece into the small area behind the fuel tank, which also comes right up to the push-rod hole in the wing. I also put a strip of foam weather stripping between the side window and fuselage tube where it was touching. It all has helped some. I also think that closing up the wing root gap has blocked some also. I also played around with the exhaust exit out of the muffler. On my plane, I've found that a 90 degree turn to the outside towards the wing tip helps. Straight back is good, but it shoots directly into the prop which is not good. Without a cowl, straight up is good, except of the danger of rain water entry when parked which is not good. I've also thought of the motor mounts needing to be more soft, but that is another day. Then I hear about other airplanes and noise inside, so I guess that we will keep experimenting, because we can.

kb

I watch a guy pull out his i-phone, and bring up a sound level app as he was fine tuning the sound output of an outside band speaker set-up. It looked really good, and he said it worked quite well. Now I will see if there is an app for my android phone.

kb

Aha, the foam ear-plugs. The resident female guru on the other airplane site is an avid user of them, even when flying their Jabiru 3300, 6-cylinder powered plane. She also is the most convincing of the Telex 50's, and has also been talking db's. I need to see what my noise is, and it will probably scare me. Also about the radio, I too, turn it down when away from the airport, as some guys radios are just crap in transmissions, and when two people start talking at once there can be a loud squeal. I also had to keep monkeying with my strobe wire and proximity to the headset wire that caused a loud burst of noise. Hmmmm................., more stuff to monkey with.

kb

http://knol.google.com/k/sound-and-its-measurement

A-scale is used for noise measurement, C-Scale is used for music (i.e.,
balancing your speakers).

A-scale


We often wish to measure a noise with a single measurement and this is done
by allowing the sound level meter listen to all the frequencies at one time,
in the same way as the ear. An electronic circuit in the meter then
emphasizes the middle frequencies, just as the hearing system does. The
results are usually quoted as dB(A) and the 'A' is an important tag telling
us how the measurement was made.

Measurements in db(A) are widespread and convenient but you must remember
that they are a compromise and tell us nothing about the frequency content
of a noise. The ear can tell a difference between a washing machine and a
telephone buzzer because their sounds have a very different structure. But
such different sounds may give identical readings in dB(A).

for the uber geeky ;)

http://en.wikipedia.org/wiki/A-weighting

My mount donuts are black. I don't know how to tell torque/thrust differences among the four mounts.

Sent from my iPhone

they are painted with a dot of color and this may not be visible or have
worn off. If they are soft you will easily be able to push with a thumb and
have the rubber deflect. If they are green (hard) you will struggle (unless
very strong) to get them to deflect much. Yellow is in between. You can
get it to deflect with some effort. If they are purple (very hard), good
luck you will need a tool to get it to deflect and a lot of umph.

Don't know if this helps, very subjective.

Hi Alan
You dont really fly your JT2 with a dog in the back?
Fred

She convinced me and I am happy with my choice.
Fred

Yes I do. Two miniature doxies.

-Alan Cossitt

>From my iPhone. Please excuse typos and terseness.