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  #81  
Old 01-21-2007, 12:13 AM
Ltvscout Ltvscout is offline
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Originally Posted by Carl@Semroc
You have to login to your account on Semroc site first. All the SVDT members can get to protected pages.

I was logged in already. I logged out and then back in and it then came up. Very impressive list of motors there, Carl! I like!
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  #82  
Old 01-21-2007, 08:03 AM
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CPMcGraw CPMcGraw is offline
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Originally Posted by Carl@Semroc
It is not so easy to get a C10 in 18mm. BP burns at about .8" sec at 100 psi, so... a port burner would burn out in about .35 seconds so you would get a B14, 3/4C19, C28, D56, etc. Never had luck with a C28 and never even tried a D56. To get a C10 in an 18mm package would require a much lower burn rate propellant...


A longer casing would not contribute to greater pressure in this application, right? It would only "sustain" a given rate. You really need volume around the middle (diameter) to generate the needed pressure, and this is why we see BP C11s and D12s in 24mm rather than 18mm? It gets down to how much propellant is burning at a given instant of time rather than how much propellant gets burned over a(n extended) length of time.

That 3/4C19 interests me, then...
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  #83  
Old 01-21-2007, 10:20 AM
Eagle3 Eagle3 is offline
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Originally Posted by Carl@Semroc
That is good to know. I think I have a few around here somewhere. I will probably fire a few on the test stand when I get time.

I think Centuri was trying to pack too much in each step since several tubes are bulged.


I never got my hands on any Centuri B's. I still have a ton of Centuri mini A's, but I think the previous owner temp cycled them. Everyone has gone off like an M-80. I still have a couple of packs of MPC B's, but *sniff* I don't have the heart to open and burn em.

The Semroc motor lineup looks great and I see so many vacant holes being filled. That D5 will be a great motor! B4... B7.... B14... man, I can't wait!!!
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  #84  
Old 01-21-2007, 10:56 AM
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Carl@Semroc Carl@Semroc is offline
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Originally Posted by CPMcGraw
A longer casing would not contribute to greater pressure in this application, right? It would only "sustain" a given rate. You really need volume around the middle (diameter) to generate the needed pressure, and this is why we see BP C11s and D12s in 24mm rather than 18mm? It gets down to how much propellant is burning at a given instant of time rather than how much propellant gets burned over a(n extended) length of time.
That is correct.

Quote:
That 3/4C19 interests me, then...
Large rockets for school yards!
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  #85  
Old 01-21-2007, 11:28 AM
foose4string foose4string is offline
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Yep, the D-5 will sell like hotcakes. I saw the A8, B6, but why no C6 on the list?

EDIT: Sorry, I see it now, didn't see it earlier when I looked.
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  #86  
Old 01-21-2007, 01:31 PM
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Originally Posted by Carl@Semroc
...Large rockets for school yards!


Depends...

The C10-3 was what I was looking at, and it took the Star Ranger up to 290'. The D10-3 took it to 470'. It got the model off the pad quickly -- 20" for the C10 versus 35" for a C11.

How does the 3/4C19 compare to a C10? Or even to a D10? The "19" tells me this is a port burner, and the formulation would burn rather quickly, producing a lot of internal pressure. I don't have any graph to compare with, so I'm just guessing it could lift a model of comparable size (2.9 oz) to flight velocity in about 14" instead of 20". The down side would be the short duration of the sustainer burn following the spike.

Star Ranger is a "big" model at 40.2" long...
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  #87  
Old 01-21-2007, 01:47 PM
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Originally Posted by CPMcGraw
Depends...

The C10-3 was what I was looking at, and it took the Star Ranger up to 290'. The D10-3 took it to 470'. It got the model off the pad quickly -- 20" for the C10 versus 35" for a C11.

How does the 3/4C19 compare to a C10? Or even to a D10? The "19" tells me this is a port burner, and the formulation would burn rather quickly, producing a lot of internal pressure. I don't have any graph to compare with, so I'm just guessing it could lift a model of comparable size (2.9 oz) to flight velocity in about 14" instead of 20". The down side would be the short duration of the sustainer burn following the spike.

Star Ranger is a "big" model at 40.2" long...
It is just a .35sec spike, no sustainer.
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  #88  
Old 01-21-2007, 02:07 PM
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It is just a .35sec spike, no sustainer.


Is the curve like this...? (See attached RSE file)
Attached Files
File Type: rse SEMROC Astronautics Corporation3-4C19 [18].rse (955 Bytes, 8 views)
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  #89  
Old 02-01-2007, 08:41 PM
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Chas Russell Chas Russell is offline
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Default Preliminary Engine List (Small)
I have logged out and in several times on two computers and copied and pasted the URL and all I get is three pages of engine related parts. Guess I missed the meeting about the secret handshake.

Plus I can't open .rse files...

I'll go back to fighting with Best Buy over the piece o' stuff TV stand they mucked up.

Chas
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  #90  
Old 02-01-2007, 09:53 PM
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Originally Posted by Chas Russell
I have logged out and in several times on two computers and copied and pasted the URL and all I get is three pages of engine related parts. Guess I missed the meeting about the secret handshake.

Plus I can't open .rse files...

I'll go back to fighting with Best Buy over the piece o' stuff TV stand they mucked up.

Chas


RSE -- RockSim Engine file...

RSE files are opened by RockSim's Engine Editor program for editing and adding new motors to the various vendor's files. This program also reads ENG files from RASP; you can open a file from one type and save to the other.

RockSim reads RSE files when it cranks up; that's where it gets all of the engine data for simulations.
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