Big Test Lady FWE arrives in Aero/Combustion Laboratory

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tufty
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Re: Big Test Lady FWE arrives in Aero/Combustion Laboratory

Post by tufty » Mon May 04, 2009 7:58 pm

Mike Everman wrote:There is a serious problem with that design. I am no expert, but I think it simply will not stand the heat!
Obvious attack post. Ban request!

Oh, and M, you continue to astound me with your ability to pull a set of parameters "out of your hat".

Mark
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Re: Big Test Lady FWE arrives in Aero/Combustion Laboratory

Post by Mark » Mon May 04, 2009 11:29 pm

I'd be interested in seeing how that cone would work as a jam jar. The idea seems to suggest a swirled effect, not unlike that of a typical jam jar.
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Re: The plot thickens

Post by larry cottrill » Tue May 05, 2009 3:03 am

Attempting (perhaps vainly) to get back on track:
milisavljevic wrote: Define: "short cone". To answer the follow-up question: Yes, I will do it. Tell me when you need it.
Well, when I wrote it I just meant something that would be better than the slight flare, i.e. something just adequate to optimize the tuning with minimum effort. Of course, if one wanted, a much bigger cone could be designed that would make the engine more compact and reduce the lockup ratio to say, 5:1. But that would be a BIG cone. The advantage would be that we would have test data for an engine that someone might actually want to build! Not big enough for a kart, but certainly enough for a lightweight bike or trike if world-beating performance wasn't an issue. It's just that now that we have weeks rather than days or hours, it seems a shame to settle for a non-performer out of such a big motor and so much effort already expended. Greg, I think we three need to reach a consensus on what we want. And Greg, you set the target date, somewhere reasonably far out. I can fairly accurately build about anything we need for the tail end.

Greg, I think we need one more kind of test -- Collins sensors. What you would do is drill a 7/16-inch hole where you want one and weld on a 10Mx1.0 nut. The sensor is a CM-6 spark plug, with the gap left narrow as it is right out of the box. You bring off a low-voltage wire connected to the positive side of a 9V battery; the negative side goes to ground THROUGH a resistor -- try 1000 ohms to start with. What happens is, with air there will be zero current across the gap, and zero voltage drop across the resistor. As the gap is filled with ionized gas, current increases and a voltage drop appears across the resistor. You hook an oscilloscope or sampling voltmeter across the resistor to get the trace. What you're measuring is the rapidly pulsing degree of ionization. If this works, it would be a good thing to try out along the tailpipe; also in the intake and transition. You could use one at the front dome with the output going through a Schmidt trigger, providing a sync pulse to superimpose on the dynamic sensors, if the measuring rigs can handle that. (This would show you the delay in flame front arrival at every tested point in the engine!) You should at least try one in the tailpipe, to see if it will really work, and if the coming and going of the "cold air piston" can be plotted. I named this idea after Viv Collins, who originated it.

Greg, as to the observation of the left side of the chamber running hotter than the right side: Remember, on the right side you have all those little fittings and caps. Those are a considerable source of radiative heat sinking. There should also be a fairly large "cold" area on the belly of the chamber surrounding the weld zones of the vise mount lug.

L Cottrill

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Re: The plot thickens

Post by milisavljevic » Tue May 05, 2009 3:55 am

Hello Simon,
tufty wrote:And sometimes comes with a Cadbury's Flake in it.
Now there's a well-defined short cone we can all agree on! Yum! :D
tufty wrote:M, you continue to astound me with your ability to pull a set of parameters "out of your hat".
Not knowing how you meant this, and not wanting to know if it's not nice, I don't know how to respond.*

Cheers,
M.

*If you're counting, that's four "nots", three "knows" and two "hows". Plus one 100% hand-coded "hat". :wink:
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avast!
Cap'n M.

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Re: The plot thickens

Post by milisavljevic » Tue May 05, 2009 4:01 am

Larry,
larry cottrill wrote:Attempting (perhaps vainly) to get back on track:
The villainy! :wink:
larry cottrill wrote:Well, when I wrote it I just meant something that would be better than the slight flare...
I will endeavor to pull a practical, performance-oriented tailpipe out of my, ahem..."hat".

No worries,
Evil M.
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an' threat'nd wit' forfeiture of all ye precious loot
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Cap'n M.

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Re: Big Test Lady FWE arrives in Aero/Combustion Laboratory

Post by larry cottrill » Tue May 05, 2009 12:00 pm

Thank you, sir. Let's get one that will give that vise a good shove!

L Cottrill

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Re: The plot thickens

Post by milisavljevic » Tue May 05, 2009 12:13 pm

.
As long as there's no shoving whilst I'm busy pulling that pipe out of my... .hat.

Can I haz LOL? :lol:

Evil M.
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for ye merchants who do the prop'r t'ing only if
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an' threat'nd wit' forfeiture of all ye precious loot
hear this - so-called stand-up guys YE BE NOT

avast!
Cap'n M.

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Re: The plot thickens

Post by tufty » Wed May 06, 2009 4:48 am

milisavljevic wrote:
tufty wrote:M, you continue to astound me with your ability to pull a set of parameters "out of your hat".
Not knowing how you meant this, and not wanting to know if it's not nice, I don't know how to respond.
It was meant in the nicest possible way. "Remote debugging" is a really hard thing to do.

Simon

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Re: The plot thickens

Post by milisavljevic » Thu May 07, 2009 1:30 am

Hello Simon,
tufty wrote:It was meant in the nicest possible way.
I should have known. And thanks for the ice cream! :wink:
tufty wrote:"Remote debugging" is a really hard thing to do.
Indeed it is. :(

Presently, I am remotely debugging a pulsejet that is only(!) 11,000 km distant.
Trouble is, the dims reported back to me keep changing...lather, rinse, repeat.

...argh!

Cheers,
M.
no safe haven for merchant scum


for ye merchants who do the prop'r t'ing only if
ye be haul'd-up on charges b'fore ye ship-mates
an' threat'nd wit' forfeiture of all ye precious loot
hear this - so-called stand-up guys YE BE NOT

avast!
Cap'n M.

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Re: Big Test Lady FWE arrives in Aero/Combustion Laboratory

Post by larry cottrill » Thu May 07, 2009 1:59 am

M -

Regarding our test project, don't put too much stress and strain on your hat. Greg says there will be no re-building until he gets back there in about four months. Even then he'll have to carefully plan when he can work with her. He also says he never did "beef up" the connection between chamber and tailpipe -- in fact, the pipe is totally disconnected right now. So, it sounds to me like we are pretty flexible.

L Cottrill

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Re: The plot thickens

Post by milisavljevic » Thu May 07, 2009 2:47 am

.
larry cottrill wrote:M - ...don't put too much stress and strain on your hat.
Will people stop talking about my "hat". I mean...well, like everybody has one, right? So, puh-leeze! :lol:

No worries, Larry. Saved to disk.

M.
no safe haven for merchant scum


for ye merchants who do the prop'r t'ing only if
ye be haul'd-up on charges b'fore ye ship-mates
an' threat'nd wit' forfeiture of all ye precious loot
hear this - so-called stand-up guys YE BE NOT

avast!
Cap'n M.

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Re: The plot thickens

Post by larry cottrill » Thu May 07, 2009 11:00 am

milisavljevic wrote:.
Will people stop talking about my "hat". I mean ... puh-leeze!
All right -- hats off to you, sir! I for one won't mention it again.
No worries, Larry. Saved to disk.
When you know that what you have is the final word, pass the dimensions along to me and I will draft it up in "official blueprint" form. Then, sometime this summer, I'll build the tail end and ship it to Greg; he can go from there when he's ready. Don't forget that whatever we do will have to accommodate the existing tailpipe socket at the far end of the chamber. Pulsejetland Legos(TM) - ha.

L Cottrill

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