highaltitude.log.20070129

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[21:55] <CablitoE> hey
[21:56] <CablitoE> icez - least idle
[21:56] <CablitoE> rocketboy
[22:04] <rocketboy> hiya
[22:05] <CablitoE> hey pretty idle now
[22:05] <CablitoE> you into model rocketry?
[22:06] <rocketboy> yep - mostly the high powered stuff
[22:06] <icez> I've done some too
[22:06] <icez> not the high-powered kind =p
[22:07] <CablitoE> check these links
[22:07] <CablitoE> http://www.youtube.com/watch?v=pX4NPKNjSAE
[22:07] <CablitoE> http://www.youtube.com/watch?v=lQ9Pg649MhE
[22:07] <CablitoE> kids doing nice rockets
[22:07] <CablitoE> hybrid ones too
[22:07] <CablitoE> those that rocket building books says its impossible for amateurs to create
[22:08] <CablitoE> true they did disregard basic good sense safety at first, but that is something that comes with maturity.
[22:08] <CablitoE> I dont wanna die before doing a rocket engine
[22:09] <CablitoE> and if choosing how to die, being blown up by one comes before getting run over by a car.
[22:14] <rocketboy> interesting stuff - is that PIC (plastic Ignighter Cord) you are lighting it with?
[22:15] <CablitoE> Thats not me - I wish
[22:15] <CablitoE> I live in an apartment; I need a real house with a garage for my tools
[22:15] <rocketboy> its a bit scary
[22:15] <CablitoE> well, rocket engines are scary
[22:16] <CablitoE> the line of safety is so thin you can barelly see it with the naked eye.
[22:16] <rocketboy> they need somthing between themselves and the engine
[22:16] <CablitoE> oooo yeah
[22:16] <CablitoE> either acrylic or 100 feet of air
[22:16] <CablitoE> still their experiment is safer than pulse jets
[22:16] <rocketboy> the ply baffels would have been good
[22:17] <rocketboy> humm
[22:17] <CablitoE> people playing with pulsejets are insane... when the metal is RED... and black stains start to show
[22:17] <CablitoE> that shows how bad quality metal they used
[22:17] <CablitoE> even though pressure is "easly" escaping through the back
[22:17] <CablitoE> black stains in the glowing metal is a bad sign
[22:19] <CablitoE> and shrapnel from the valves on pulsjet escape at near-mach speeds
[22:19] <CablitoE> The main problem with home brewed rocket engines is cooling
[22:20] <CablitoE> because to produce a combustion chamber with water cooling "veins" is impossible on home budget
[22:20] <rocketboy> you mean liquid morors
[22:20] <CablitoE> unless of course you have prime machining skills
[22:20] <CablitoE> yeah liquid rocket engines
[22:21] <rocketboy> yeah - I tend to steer cler of those
[22:21] <CablitoE> I am not fond of solid ones
[22:21] <rocketboy> I use solids aor hybrids
[22:21] <CablitoE> Well, hybrid is a very hibrid therm
[22:21] <CablitoE> I consider any mix of liquid/gaseous fuel/oxidant a liquid fuel one
[22:22] <CablitoE> Hidrogen Peroxide + Petrol derived fuel for non cryogenic seems reasonably safe
[22:23] <CablitoE> except for the fact that Hidrogen Peroxide sets a lot of things on fire on contact, but so does oxigen.
[22:23] <rocketboy> well way safer than liquid/liquid engines
[22:23] <CablitoE> In my mind there are two key limiting factors for amateur rocketry, fuel safety + Fuel Pump.
[22:23] <CablitoE> Fuel pump for rockets is a very delicate subject
[22:24] <rocketboy> it always has been - one of the key invetions for the V2
[22:24] <CablitoE> I´ve always wondered if a regular RC nitro engine with gearboxes to lower the insane 20.000 rpm to 100 rpm and use that to drive a pump
[22:24] <CablitoE> a gear-based pump, for high pressure and simplicity
[22:26] <CablitoE> Then off course you get the problem that the RC engine is air-breathing, but then in the same line, perhaps an eletric engine. I mean, these concepts are unsuable for high performance large scale rockets, but on amateur levels, one might just be able to produce the PSI needed
[22:27] <rocketboy> I think they used things like a hydrogen peroxide engine to drive the turbo-pump
[22:28] <CablitoE> On large scale, but imagine smaller rocket engines
[22:28] <CablitoE> the cooling factor can actually be used to generate thrust I believe
[22:28] <CablitoE> you´ve got this glowing hot metal
[22:29] <CablitoE> and you can both cool it and get some thrust by pulverising water into it (having a secondary nosle covering the whole engine)
[22:33] <rocketboy> I think I understand what you are saying - but conventionaly they use the cryogenic liquid fuel to cool the nozzel
[22:34] <CablitoE> that does not happen with hidrogen peroxide though
[22:34] <rocketboy> and it preheats the fuel/oxidiser in the process
[22:34] <CablitoE> but the whole thing is
[22:35] <CablitoE> ok, imagine u can make ur amateur rocket rise 80 km
[22:35] <CablitoE> still a long way from space
[22:35] <CablitoE> and orbit is a whole different show
[22:35] <CablitoE> hell, a whole different story
[22:35] <rocketboy> hydrogen peroxide engines normally use a catalist to break down the HP and then add a fuel as a secondard combustion
[22:36] <rocketboy> the HP is a monopropellant
[22:36] <CablitoE> yeah but there are some HP + Kerosene engines
[22:36] <CablitoE> I wonder if alchool is not an usable fuel.
[22:38] <rocketboy> yeah but I think they work as described - HTHP + catalyst as a mono propellant - then kerosene is added beyond that in a secondary chamber
[22:39] <CablitoE> sort of an after burner? just using the Oxigen that comes from the HP decomposition?
[22:39] <rocketboy> the HP has broken down in water + O2 (I think) then the kerosene is added to burn with the O2
[22:40] <rocketboy> the water (stream) just gets hotter
[22:40] <rocketboy> steam
[22:40] <CablitoE> Yeah the catalyst breaks into O2 + water
[22:40] <rocketboy> you need High Test HP
[22:40] <rocketboy> HTHP
[22:41] <CablitoE> highly purified HP scares me
[22:41] <CablitoE> the germans suffered quite severe casualties playing with it
[22:41] <CablitoE> and they were in military level budget
[22:42] <CablitoE> have you done any experiments in this kind of rocketry?
[22:43] <rocketboy> yeah - well its a lot safer than Liqid Hydrogen/ Lox
[22:44] <CablitoE> I get the creeps just from the thought of handling those
[22:45] <CablitoE> I´ve just looked up some electric pumps, minature (35grams) that put out 160psi
[22:45] <CablitoE> not enough I am afraid
[22:47] <rocketboy> multipy that by about 30
[22:47] <CablitoE> yeah, I just dont like the idea of having the high pressure helium tank to pressurise fuel tanks
[22:48] <CablitoE> I rather thing of a pump doing the job
[22:48] <CablitoE> everytime you need high pressure anything, it means 2 things: heavy cilinders, risk of explosion
[22:49] <rocketboy> thats why they used pumps
[22:49] <CablitoE> Also something I never find solid info is engine metal choise
[22:50] <CablitoE> the golden book of amateur rocketry says copper!?
[22:50] <rocketboy> lots of interesting engineering problems to solve
[22:50] <CablitoE> it doesnt sound good.
[22:50] <CablitoE> ooo yeah, at the end I think if you build an engine that sucessfully run you can actually make a website and say in large fonts "I´ve done it"
[22:51] <rocketboy> are you talking about the nozzel or combustion chamber
[22:51] <CablitoE> I think both, I dont know if you can make them separately (for complexity purposes)
[22:51] <CablitoE> talking about machining it at home
[22:53] <rocketboy> copper - I'd be surprised - I guess if its being cooled
[22:53] <CablitoE> +1000º C melting point but still
[22:56] <rocketboy> its just a bit soft
[22:56] <CablitoE> I´ve seen some engines made of it
[22:57] <CablitoE> suffering throat wear pretty bad
[22:57] <CablitoE> what about nickel
[22:57] <CablitoE> not sure how expensive it is at good grades
[22:57] <CablitoE> but its very resistant to temperature
[22:57] <icez> aluminum?
[22:58] <icez> oops.
[22:58] <icez> nevermind
[22:58] <icez> :P
[22:58] <rocketboy> titanium
[22:58] <CablitoE> Titanium steps into the non amateur area I think
[22:58] <CablitoE> and not sure how machinable it is
[22:58] <CablitoE> and Titanium "Catchs fire" does it not?
[22:59] <icez> it's a bit sensitive to temperature I heard
[22:59] <icez> at least temperature change
[22:59] <CablitoE> It appears it actually literally catches on fire before melting
[23:00] <icez> a lot of metals do that
[23:00] <rocketboy> adds to the combustion ;-)
[23:00] <CablitoE> well, it does when high-temperature + lots of oxigen
[23:00] <CablitoE> lol
[23:00] <CablitoE> might as well have a 100% eficient engine that burns all the fuel including itself
[23:01] <CablitoE> Ok guys I gotta go dinner, be back in a few minutes - away
[23:03] <rocketboy> dinner so late in the day - you will get indigestion
[23:03] <rocketboy> ;-)
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[23:26] <CablitoE> hehe
[23:32] <Weiss> at about 500K (iirc), and if there's friction, titanium burns very quickly
[23:34] <Weiss> but a lot of the clever metallurgy that goes into things like jet engines are to give it a decent life.. which you might decide you don't need
[23:47] <CablitoE> Its also about how well I can machine it
[23:47] <CablitoE> if there was an alloy that is perfect but I can machine on a domestic lathe
[23:47] <CablitoE> ...
[00:00] --- Tue Jan 30 2007