Flyrockets.com webstat reports

Greg rolls his own....try his BurnSim program sometime. Invaluable.

Mike Fisher

Reply to
Mfreptiles
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I agree 101%... Burnsim is well worth the small support fee.

Although it can be "fun" to do the hand calculations or bounce back and forth between hacked together spreadsheets, it's nice to have most of the motor design calcs in one graphical interface.

If you're into designing your own motors, go take a look.

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-John

Reply to
John DeMar

Funny you guys should mention BurnSim... I got on a coding kick last night and added in Star grains. Couple days of testing and should have another beta readr.

Reply to
Greg Deputy

Star grains before C-slots....for shame! :)

Mike Fisher

Reply to
Mfreptiles

Fixed fin count and shape or N-fins and optional shapes?

Pardon the tech post.

Reply to
Jerry Irvine

Exactly! ;) But, the star grain geometry is well-documented on a nice webpage someplace (do a google for it).

I worked out the regression equations for bates, D-grain, and C-slot and have tested the equations in Matlab. My D-grain seems to agree with others but not with the one in Burnsim. Once I get some time to write it up in general form, I'll post these online. C-slots have three modes, depending on the depth in relation to the center point.

I'd also like to see an erosive burn factor added that triggers based on mass flow. And one that simulates "slivers" near the end of the burn. Not asking for much, eh? ;)

-John

Reply to
John DeMar

This is also a function of propellant mechanical properties and pressure so it is at least a 3-4 variable issue. Not simple.

Does it already at least factor in burning rate exponent?

This rmr thread is like entering the twilight zone and arriving at aRocket.

Tech Post Jerry

Reply to
Jerry Irvine

I've got algorithms for them all, its just a question of taking time to add them in. Did the star grain because i've got a mandrel here i wanna try out.... Yeah, CSlot probably next.

Reply to
Greg Deputy

Fixed shape (triangle point) but any number of points.

Reply to
Greg Deputy

Not as far as erosive burning is concerned, but in regular steady-state conditions, yes. I'm currently researching various erosive burning prediction methidologies and trying to decide which I want to use. So much to choose from....mass flux, gas velocity, blah blah blah, etc. etc .etc....

Reply to
Greg Deputy

I've saved some references and papers. I'll try to forward them to you when you get closer to working on the erosive burning sims.

Please add some sort of "emperical thrust correction factor" to override the ideal Cf in the new version.

-John

Reply to
John DeMar

The TRA page was in need of a major revamp if it was going to welcome newbies from Discovery. IMHO, the new TRA web page is a big improvment over the old one. As is the not quite as new NAR page, although it didn't have as far to go.

As to old browser support, the NAR page works fine under NS 4.72. The flyrockets.com page didn't, but Greg IMMEDIATELY fixed the problem. [His stats not only show NS 4.x visits, but even NS 3.x visits!]. Kevin contacted me re: the TRA page issues, but as of today they remain.

I did check NAR, TRA, and FlyRockets home pages under Mozilla from Linux, and all looked OK. Any one try Lynx yet???

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

How about one to simulate blown nozzles :-(

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

Reply to
Bob Kaplow

How did you define the web distance in a star grain ? Did you just take the shortest distance from the tips of the star to the perimeter or did you do some type of weighted average ? Your burnsim software is great but getting the burnrate coefficents for a particular formulation is a whole other story.

THX, John

Reply to
John Ritz

Actually I have been meaning to add in nozzle erosion and pressure drop transients. Time TIME I need more TIME!!!

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Reply to
Greg Deputy

Web thickness in a star grain is the distance from one of the tips to the wall. The actual progression of the burn is calculated mathmatically.

Yup, characterizing propellant is work, but really isnt that bad. Burn a few end burners at different pressures, get the pressure and burn rate, fit the curve, you're good to go!

Of course, all the details involved always get ya.

Reply to
Greg Deputy

If you just described a "tip" as the ID then bad. If you just described a "tip" as the OD then good. The description did not specify.

Jerry

Reply to
Jerry Irvine

Right, sorry, let me be more clear. Tip as in OD.

Reply to
Greg Deputy

It looks like it may have worked twice........total visitor was hovering around 30K, after the rerun it's gone up anther 50% to 45K.........guess the second goround caught all the football crowd. The first obvious memory of the show which comes to mind is the rockets, but the first thing which comes to mind with people is 'You sir are a liar!' .........terribly autocratic, it really wiped out all the enthusiastic whooping and hollerin' he did earlier in the shows. It was a classic shoot first and ask questions later........

Reply to
Chuck Rudy

I therefore concur.

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Iroc, but not like LOC, like I rock!

Just Tech Jerry!

Reply to
Jerry Irvine

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