Rich Thomas wrote:
As far as working supersonic propellers, that has been researched quite
a bit, but the noise is the big issue. They can be made to work with
the right geometries, and pretty well, but quite noisy.
I've been thinking about making a vertical axis windmill, with fiberglass
cloth over foam wings. I'm thinking I want to keep the speed under
800fps
to avoid supersonic airflow, but 600-700fps might be better in
practice.
With a 60 foot circumference, you could do ten rps (600 rpm) and still
have only a 600fps wing speed.
Aren't these bird choppers? I thought
Rich Thomas wrote:
The actually sound was quite interesting to hear too -- it sounded
quite choppy as the individual shock waves passed ears, with the
chopping sound kinda overlaid on the very loud roar of the whole
thing. The chops were due to each blade rotation and how the shocks
radiated
Those things are spinning at maybe 2rpm? Say 3 diameter, that
would be .75 ft circumference, that's only 250ft/sec, way subsonic
(sonic speed is ~1050fps at ambient) esp at higher temps. They might be
chopping the exhaust into little pulses as it goes through the blades.
--R
John
Rich Thomas wrote:
Those things are spinning at maybe 2rpm? Say 3 diameter, that
would be .75 ft circumference, that's only 250ft/sec, way subsonic
(sonic speed is ~1050fps at ambient) esp at higher temps. They might be
chopping the exhaust into little pulses as it goes through the
On Tue, 1 Jan 2008 08:45:32 -0800 Jim Cathey [EMAIL PROTECTED]
wrote:
cloth over foam wings. I'm thinking I want to keep the speed under
800fps
to avoid supersonic airflow, but 600-700fps might be better in
practice.
With a 60 foot circumference, you could do ten rps (600 rpm) and
On Tue, 01 Jan 2008 14:20:38 -0500 Mitch Haley [EMAIL PROTECTED] wrote:
Craig McCluskey wrote:
The Savonius turbines do have the advantage of a vertical axis and its
consequent omnidirectionality, but they have the disadvantage of
curved blades. I have some information (someplace
Craig McCluskey wrote:
The Savonius turbines do have the advantage of a vertical axis and its
consequent omnidirectionality, but they have the disadvantage of curved
blades. I have some information (someplace around here ...) on a different
type of vertical axis windmill, where the top of
On Tue, 1 Jan 2008 13:16:53 -0700 Craig McCluskey [EMAIL PROTECTED]
wrote:
On the subject of bird strikes, I think the windows on my house get
hit more than any home windmill. I've attached a .pdf article on the
subject.
I think the article's perspective on bird strikes is summed up by
-Original Message-
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of Craig McCluskey
Sent: Tuesday, January 01, 2008 7:07 PM
To: Mercedes Discussion List
Subject: Re: [MBZ] The dearth of high fidelity...probably more accurate
On Tue, 1 Jan 2008 13:16:53 -0700 Craig McCluskey [EMAIL
Chris,
My last pair of speakers for my home system were transmission line. VERY
nice tight bass and response was +-.5 20-20khz and down -2 at 16hz.
Awesomeok, and a tad expensive$6,000 a pair. They're discontinued
but the company makes almost nothing but TL speakers. I prefer them.
It's
I have built TL enclosures using plans from both EV
and Altec Lansing - if well designed, a TL enclosure
with the proper drivers can do some serious damage to
your eardrums.
The EVs I built way back in my teen years would easily
rattle windows both at my house and the neighbors when
cranked up.
What is transmission line ? Sounds like something you'd find at the
top of a utility pole.
In college I built a set of speakers using EV Voice of the Theater
plans. 15 EV drivers (cast frames -- no stamped steel here) horn
loaded in a bass reflex enclosure and horn tweeters. STAND BACK!!!
LWB250 wrote:
I have built TL enclosures using plans from both EV
and Altec Lansing - if well designed, a TL enclosure
with the proper drivers can do some serious damage to
your eardrums.
I'm pretty happy with the old DCM KX10 and KX12 speakers. Too
bad you can't just swing by Circuit
The nice thing about building your own cabinets was
that the money you saved could be put towards really
good drivers. I was lucky, as we had a nice
woodworking shop at the house, so building something
like this was pretty elementary.
Dan
--- Mitch Haley [EMAIL PROTECTED] wrote:
I'm pretty
It seems than at Mon, 31 Dec 2007 11:36:39 -0500, Allan wrote:
What is transmission line ? Sounds like something you'd
find at the top of a utility pole.
A speaker standing all by itself (no cabinet) is call free air.
This situation is not very efficient because when the cone moves
forward,
I'm pretty happy with the old DCM KX10 and KX12 speakers.
I have DCM Time Frames. Bought new, serial number 510 (or
thereabouts). IIRC they were around $500 at the time.
Recently picked up a pair of unmarked DCM bookshelf
speakers at Goodwill for $20. Not sure what I'll use
them for.
-- Jim
Jim Cathey wrote:
I'm pretty happy with the old DCM KX10 and KX12 speakers.
I have DCM Time Frames. Bought new, serial number 510 (or
thereabouts). IIRC they were around $500 at the time.
Recently picked up a pair of unmarked DCM bookshelf
speakers at Goodwill for $20.
I was reading
They are also sometimes referred to as folded horn
enclosures. I believe this was the term used by EV
and others.
Dan
--- Fmiser [EMAIL PROTECTED] wrote:
It seems than at Mon, 31 Dec 2007 11:36:39 -0500,
Allan wrote:
What is transmission line ? Sounds like
something you'd
find at
On Mon, 31 Dec 2007 12:28:16 -0800 (PST) LWB250 [EMAIL PROTECTED] wrote:
They are also sometimes referred to as folded horn
enclosures. I believe this was the term used by EV
and others.
Dan
Where does the Klipsch horn fit into all of these?
Craig
--- Fmiser [EMAIL PROTECTED] wrote:
What is transmission line ? Sounds like
something you'd
find at the top of a utility pole.
Allen
There are numerous ways to try to make this cabinet
interact
with the speaker itself. Some of these are infinite
baffle, horn loaded, acoustic suspension, bass
reflex, passive
There are many different horn throat types. There's your typical exponential
horn, which is what you'd see in EV and then there's a tractix. The tractix
is more of a square throat as opposed to regular. Think of the difference
between a 4:3 tv for Tractix and a 16:9 for exponential. There are
One of my professors in college (Purdue, Aero/Astro), who went to MIT,
and later became head of the Dept at Purdue, told a story in our
Aerodynamic Noise class of having made a large speaker while an
undergrad at MIT, which was installed in a dorm room (or, rather, the
modified dorm room was
I remember something from years ago about the speed of propellers being
limited because the tips broke the sound barrier. Then they came along with
fanjets. It would seem that the fanject blade tips would have the same
problem as the propeller blade tips. Did your experiments help solve that
If I remember correctly, the Air Force and Navy tried some supersonic
propeller turbo-prop planes in the early 50's before jets worked well
enough for carrier work (no range) -- the props were counter-rotating
and rather short, and worked just fine other than the normal problems
with
http://www.murphyauctions.net/westernvideo.html
get your new toys here. I have nothing to do with it. Just got the
notice and given all the chatter, must be someone who needs to stock up
clay
On 31 Dec 2007, at 12:16, Mitch Haley wrote:
Jim Cathey wrote:
I'm pretty happy with the old
Our experiment only caused problems. The whole point was to generate
some aerodynamic noise, which it did really really well. That and a
bunch of other annoying effects. The noise had some interesting
attributes in regards to where the most sound energy was being
radiated. I forget the
It seems than at Mon, 31 Dec 2007 13:43:42 -0700, Craig wrote:
On Mon, 31 Dec 2007 12:28:16 -0800 (PST) LWB250
[EMAIL PROTECTED] wrote:
They are also sometimes referred to as folded horn
enclosures. I believe this was the term used by EV
and others.
Dan
Where does the Klipsch horn
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