Jerry, must you always get so contentious about everything? You do have good data to impart to the rocketry community but you immediately start jabbing and raise everyone's hackles....we know you live for a good argument but tone it down. You frequently push my buttons, and to my chagrin I often respond in a negatively, that's my fault, but how about sticking to what's important to this community and offer advice not jibes....I'll try to do the same, not for you - for me. Lew
> I dunno about hybrids, but in my experience iced water will chill a
>> bottled beverage faster than ice alone.
>
>ICE melts and produces ice water. I am not suggesting draining the >water.
>
>Pratt in his "infinite wisdon" was suggesting water alone.
>
>Hybrid coolers double as beer coolers really well.
>
>Jerry
>
Lew Garrow TRA 7181 L3 NAR 77928 L3 METRA VP NAR L3CC
now that not only would work, but it'd look cool too, especially if you add a bit of water for the fog effect! Lew Garrow TRA 7181 L3 NAR 77928 L3 METRA VP NAR L3CC
To nearly completely wear out a phrase oft used by the notorious Mr. Irvine:
Point
I've sometimes toyed with the notion of marketting a modified Kool-a-tron electronic ice chest with a feedback loop based on bottle pressure. Just set the thing to maintain a specific bottle pressure. I have far too many other things on my plate, though...
This will definitely help, and if you can't shorten the fill line, insulate it. Your typical fill line has a 0.0625" to 0.125" ID, which means that your nicely-chilled N2O is flowing in a thin stream down a heat exchanger before it gets to the pad!
In typical scenarios, the thermal mass of the case vs the thermal mass of the incoming N2O is such that chilling the case will have only a minor effect. Keep in mind that N2O has a similar heat capacity to water, while aluminum is rather lower. Insulating the tank may help some, but only if the load is going to sit on the pad for quite some time. Which it typically doesn't.
I think this suggestion alone could make a HUGE difference. If somehow this suggestion could be widely adopted it would be very sweet indeed. Product idea for you?
It definitely does at the rack based launches I have been to, especially LDRS.
"Scott Harrison" wrote in news:0F2Pa.424499$ snipped-for-privacy@news1.calgary.shaw.ca:
Not to dispute you, but doesn't the space blanket somewhat impede evaporation?
This is a heat transfer problem. Heat flows from the higher temperature object to the lower temperature object. If you want to slow down the heat transfer, you have two options: decrease the temperature differential, and decrease the heat conductivity.
I agree that evaporative cooling could be used to decrease the temperature differential, but there has to be some evaporation.
Good points, Gary and Marcus and Scott. Thanks to all for their friendly and helpful comments. (I'm ignoring certain comments that weren't helpful or friendly.)
I'm looking for solutions that simplify, or at least don't complicate further, a system that is already too damn complicated. The water-jacketing trick came straight from Dave Griffith, who assured me he does NOT use ice in the desert. Not that it matters. I think icing down your NOX tank is no harder than icing down your cooler full of soda, which is essential on the way to the field anyway.
I'm going to gather up this information and write an article about "nitrous conditioning," and post it on
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Mike Dennett sent me some data on temperature vs. density of NOX, and we clearly want the stuff to be around 70 degrees for best performance, pressure issues aside.
Poor ol' Art Upton was having a terrible time with the 10 pound tank I gave him to get his I80 off. My RTLS valves are rated to 900 psi, because they draw too much current at higher ratings, and because it really isn't safe to let more than 900 psi into the typical motor anyway. Art watched us fire a RATT K240 off this tank, borrowed it for his pad, and by the time he got a chance to push the button the valves wouldn't open. I still feel bad about that. Next time, Art, you're first on the runway.
Another thing I'm working on is a scale that sits under the NOX tank and has big fat LCD numbers you can see from a distance. That way, if you know the motor needs 7.8 pounds of NOX you can watch it flow into the motor. I have a tendency to be stubborn, but filling Robert deHate's M for 12 minutes was too much even for me. With the scale I would have known the supply tank was dry.
I'm also looking for a good, inexpensive pressure gauge to offer as an option on the RTLS Valve Manifold. Any suggestions?
I can get oxidizer friendly pressure gauges for 12.00 Canadian. Keep in mind that this would be a lousy way to determine whether the supply tank is dry or not. Weight is the only true way to determine actual amount left. Scott ...
Thanks, Scott! Is this the same source you steered me to for GOX regulators? I really appreciate that...you helped me tweak down the price on the GOX Box. Go ahead and post the name of the source here if you like...I don't care if people buy them from the source rather than from me, as long as they get them and use them.
On the tank weight project, I called a couple of bathroom scale manufacturers yesterday and learned some things. It may be cheaper to ask my local electronics genius Ivan Galysh to whip up something with a strain gauge.
Go to your local welding supply shop, and get a high-side oxygen gauge. They're usually rated from 0-2200PSI or so. I bought one from my local welding shop for about CDN$15.00.
I recommend a custom strain guage and electronics and display product. You may be able to disect bathrom scales or something to get cheaper strain guages and amplifiers, but maybe there is a need for a "smart scale" with tare and all.
Doug, that "goofy B" thread is standard 9/16"-18 RH O2 welding hose fittings. If you unscrew the fitting (and boy howdy is it in tight), you will find a 1/4"NPT-anything coupler goes in nicely.
Marcus, In addition to building oddrocs, I make my own salsas. To preserve them, I place them in a latge pressure cooker and process them at 15 psi. Since I have electric heat, it's sometimes tricky to get the heating process just right so that the relief valve rattles but doesn't blow off. I use a wet sponge and place it on the outside of the pressure cooker if it gets too energettic and it immediately drops the pressure as it converts some of the water on the sponge to steam. Bottom line: evaporative heating sure does work and if you have good conductivity, it works quickly.
Mark Simpson NAR 71503 Level II God Bless our peacekeepers
Actually, electrical "plumbing" is hollow, too. Most of the current density is on the surface of a conductor. And most of the energy is propagated via the field outside of the conductors. So you could say that plumbing is inside out compared to electical wiring. :)
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