Nozzle Question

[jthompso]

There's a nozzle style that I remember reading about and would like to experiment with but I can't remember the name. Essentially it was a tube with a tear-drop shaped insert inside of it. Hopefully somebody will know what I'm talking about.

[Al Belli]

Hi jthompso,

The name is " aerospike "

Go to http://www.hybrids.com/aerospike.htm
and see the video.

Also see http://www.dfrc.nasa.gov/Gallery/Photo/ ... 13-146.jpg

And http://www.hq.nasa.gov/office/pao/Histo ... ro_faq.htm


Al Belli

[jthompso]

I've read about the aerospike nozzle before but this one seemed different--although maybe I'm wrong. First of all the insert was entirely contained within a tube, and also I can't remember whether the exhaust gas hit the point of the teardrop or the round part of the tear drop. I'm trying every term I can think of to find the site again, when I do I'll post the link.

[Zippiot]

Does that work with solid fuel also? Too many solids in exhaust maybe...

[Ray]

I've seen them work with solids...if you do it right, there aren't a lot of solids in the exhaust.

[Zippiot]

I read up on them and yes, they have been tested in solid motors.

Anyone have a cross sectional view, this looks like a fun thing to play with.

Ray chimed in before I could answer my own question... :(

[Zippiot]

What if you made one out of copper? Think it'll make the flame a pretty green? I say that because I recently got a nice chunk of copper and have a friend with a lathe...

[Ray]

Copper doesn't work well as a nozzle, it melts at too low of a temp.

Its a bitch to machine too...sticky and work hardens very quickly.

If you want a green flame, barium nitrate is what you want...careful, its toxic.

Copper will give you a blue flame.

[heada]

I would think a nozzle made of copper would be problematic. Most solid rocket motors (APCP) that I have worked with have exhaust temperatures of between 1500 and 2500 degrees F. I fear it would get too hot and ablate too rapidly if not burn directly. Also, I don't know the properties of copper at those temps AND the pressures the motors run at (between 500psi and 1500psi)

Most reusable nozzles I've worked with (29mm, 38mm, 54mm, 75mm motors) are all using turned graphite nozzles because they don't ablate hardly at all and handle the temps and pressures with no issues. They are somewhat fragile if dropped, so care must be taken when installing/removing/cleaning them. Without weighing them, I would guess that a turned graphite nozzle and a nozzle made from something like nickel would be near the same weight, so I don't see a savings there.

-Aaron

[Zippiot]

Well copper does melt at 1984 F and has a density of over 8 g/cm^3
Nickel has the same density (or clsoe enough) and its melting point is 2650 F.
Graphite can withstand much higher temps, but it does ablate...I just don't know the numbers...
Also its density is just over 2g/cm^3, so it is much lighter than nickel or copper and withstand higher temps.

While graphite may be the standard others can substitue, maybe a copper nickel alloy (like that used in nickel coins, melts around 2200 F) b/c finding pure nickel is more of a challenge than it may seem. But graphite seems so much better, might not bother with anything else.

[Zippiot]

Molten nickel dissolves graphite, just for the record.

[Jim Berquist]

google "aerospike"

It's there!!!!

I would say this motor wants to go forward!!!!!!!


Jim