D12 in slow motion on youtube

[shockwaveriderz]

Hey everybody, take a look at this slo-mo video of an estes D12:

https://www.youtube.com/watch?v=cxuDT1yewYQ

you can clearly see the supersonic jet core

prety cool huh?

terry dean

 

[jj94]

Wow, that's cool. But what do you mean by supersonic jet core?

 

[shockwaveriderz]

Wow, that's cool. But what do you mean by supersonic jet core?

By supersonic jet core, I mean the center plume core where the gases reach supersonic speed; typically this supersonic jet core in 18mm BP rocket motors is on the order of 3.-.4 " in diameter ; look towards the end of the burn right before the exhaust plume flames out; you will see a small diameter 2-3" length exhaust plume....

An exhaust plume is sorta like an elongated teardrop shaped onion: its has layers to it; the inner layers have the higher temperatures and speeds; I've seen some c6 plume photos where the supersonic core was clocked at 636 m/s !

The exhaust plume becomes subsonic on the outer layers about 2-4" from the exhaust exit plane as it mixes with the surrounding air.

hth

terry dean

ps I'm sure the more educated members here can give a better scientific answer.

 

[RoyGreen]

Hey everybody, take a look at this slo-mo video of an estes D12:

https://www.youtube.com/watch?v=cxuDT1yewYQ

you can clearly see the supersonic jet core

prety cool huh?

terry dean

I was hoping this would be with one of the new Casio (?) cameras with the 1000 or so FPS speed. Instead this was just a normal 30FPS video, but with each frame dissolved into the next, slowly. Still, it is nicely done.