Hard Core Rocketry

[Hospital_Rocket]

I found this today on RMR and should be attributed to our own RocketGuy101 (A new member today!) In fact if the moderators can arrange it, they should give credit for the posting to him.

Begin Plagarism Here

This past week I was in a training class to learn computational fluid dynamics (CFD). The instructors told us to bring in a pet project to practice on. I modeled an Alpha with the intent to see how launch lug placement (ala Estes TR-11) impacted the drag of the rocket. Due to time crunch of the class, slow trainer PCs, etc. I haven't completed the analysis, but the pictures were too cool and I just had to post them.

Check it out at https://www.geocities.com/rocketguy_101/strib_rocpic_7.html


Rocketguy -> welcome to the forum...

Al

 

[teflonrocketry1]

I have been playing with CFD using AeroCFD. The problem I have is getting the software to do CFD on non-conventional and asymetric designs.

Bruce S. Levison, NAR #69055

 

[rocketguy101]

Thanks, took a while to find this post. Al asked if it was OK to post it here. This is a cool forum!

 

[illini]

My Ph.D. was in computational fluid dynamics, although I left the CFD game for keeps 10 years ago. I looked up the Cosmos/floworks software that was used to generate these results and it looks like a pretty decent package. Their data sheet is pretty guarded, though. They don't seem to want to reveal too much (or maybe I didn't dig deep enough). What little I gathered is that floworks is a compressible, viscous flow solver and has some form of turbulence model. Should at least capture some of the relevant physics sufficiently to make relative comparisons (e.g., launch lug vs. no launch lug). Neat stuff. Biggest difference between CFD now and CFD when I was in it is the abundance of commercially packaged flow solvers. I have no idea how good they are, but it certainly makes it more accessible to the masses. I wrote all of the solvers I ever used...and I had to walk 20 miles to school, up hill both ways!

 

[graylensman]

So, Rocketguy 101: have you come to any definite conclusion about launch lug placement?

 

[Steward]

Originally posted by illini868891
...and I had to walk 20 miles to school, up hill both ways!

That it was in the snow...barefoot... Right???

 

[illini]

Originally posted by Steward


That it was in the snow...barefoot... Right???

You got it. In suburban Chicago you can count on school being open no matter how much snow's on the ground. And we didn't know about shoes or any of those fancy school buses back then. I'd carry a hot baked potato in my hands to keep them warm then eat it for lunch. On the way home I'd gather wood to build a fire, then study by the light of that fire. Not like kids today...no sirree. Back then you had to earn what you had!

 

[DynaSoar]

Originally posted by Hospital_Rocket
Begin Plagarism Here

This past week I was in a training class to learn computational fluid dynamics (CFD). The instructors told us to bring in a pet project to practice on. I modeled an Alpha with the intent to see how launch lug placement (ala Estes TR-11) impacted the drag of the rocket.

Amazing. High presure pockets at BOTH ends of the lug. Who'da thunk?

 

[rocketguy101]

Originally posted by graylensman
So, Rocketguy 101: have you come to any definite conclusion about launch lug placement?

No, I haven't been able to continue the analysis. As originally posted I was using this in a training class. The "real" software won't be installed until we get the version of our CAD package brought up to date. The IT folks won't let some of the groups update until EVERYONE is ready, and it is still a couple months off -- *SIGH* -

 

[rocketguy101]

Originally posted by DynaSoar
Amazing. High presure pockets at BOTH ends of the lug. Who'da thunk?

Yeah, I would like to turn the flow vector trace on to see if there is some recirculation going on or something to cause downstream high pressure. But *SIGH* I have to wait until our IT guys rev our CAD software to allow me to load the CFD package.