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Propulsion Systems

Posted by: Monroe - Wed Sep 24, 2008 12:11 pm
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Space Walker
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Post    Posted on: Thu Feb 26, 2009 2:56 am
Garvey just launched a rocket using lox/propylene, claims it has better ISP than kero and better density than methane.

http://www.hobbyspace.com/nucleus/index ... emid=10928

Full report will be on the Garvey site soon.
Be interesing how this combination will turn out but its food for thought......


Iain
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Post Balloon Launch the Way to Go   Posted on: Fri Mar 06, 2009 10:06 am
I was having my doubts about balloon launch until I had a look into DIY weather balloon projects. It's really not that hard to launch a balloon to 30KM. Also, the amateure GoFast rocket that went to space but not to orbit was 7 meters (21ft) tall and several hundred Kilos. A balloon at 30KM (100,000ft) will signifigantly reduce the required size and complexity of the rocket. A single large balloon will do as the rocket will burst it on launch.


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Post    Posted on: Fri Mar 06, 2009 12:30 pm
Charles
I've done the math and I don't see 60Kg ever making orbit in fact I dont belive it can be done with 3 times that weight. It takes X# of joules to get Y weight into orbit. How many times is this going to come up? your isp numbers could work for sure but what about Total isp? Burn for how long? and 60Kg GLOW wont even get to space. Sorry but I'll have to see some more numbers there. I could be wrong but your going to have to prove that or I'm going to get out my calculator again and prove you can't I'm tired of hearing it. Where is all this magic stuff coming from, help me out guy's will ya!
Our launcher only launches from a balloon because it's the N-Prize! The only reason we do that is to save fuel that cost money. Our 5th stage wont be recoverable becase it will be half way around the world and that's money we lose. It's 2 grand remember? Don't worry our X-Prize rocket wont be balloon launched.

Monroe

finally got that off my chest.

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Post 60 kg GLOW?   Posted on: Fri Mar 06, 2009 2:31 pm
Monroe, with all due respect, I have done the math and it is possible for a 3 stage N Prize launcher to have a total lift off mass under 60 kg. Based on the 3rd stage structure being less than 120 grams and with its engine having over 250 sec Isp in vacuum the calculations lead to the GLOW of under 60 kg, and taking off from sea level.

If no one else believes it and makes their entries larger, no problem. It probably produces some advantage to this entry, as tmaking the vehicle smaller tends to make it easier to develop, do test flights.

A slightly larger version, designated "ML-1" was being designed for placing a 1 kg Cubesat to LEO or about 100 grams to escape. It would have had a GLOW of between 100 and 200 kg. Then when news of N Prize appeared, a smaller version to be designated "ML-N" was being designed. It will be capable of 20 to 100 grams to LEO and not capable of reaching escape.

Charles Pooley


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Post    Posted on: Fri Mar 06, 2009 2:35 pm
Actually, I have to agree with Charles. I'm getting a GLOW of about 81 kg, with a payload of about 200 grams total, using three stages as well. I am using very conservative numbers for both empty weight and Isp. Plus, Charles has been doing this for a while. I wouldn't tell him he doesn't know what he's doing just yet...

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Post    Posted on: Fri Mar 06, 2009 2:57 pm
Charles
Alright then I've said my piece. I really hope you do it, I just dont see how. If you could just give a fuel burn rate I might get your point, but you don't so I wont. Maybe I'll figure out what I don't know. I'm pulling out my calculator and I'm going to work.

Monroe

P.S. Thanks for understanding and letting me say my piece without getting upset, I admit I don't know. I will find out I just have to change over to a different approach. Not understanding makes me uncomfortable.

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Post    Posted on: Fri Mar 06, 2009 4:37 pm
Charles
After looking again on the surface, I still belive your below the square cube limit and there's no way unless you share more data I'm going any farther. I dont have the time. The best part of our plan is we don't need funding for our attempt, it would be nice but we are building anyway and funding ourselfs. I just bought a nice Lathe and I'm going to make our parts. I am after all a machinist. We are willing to make parts for other teams as well if there are any interested.

Monroe

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Post    Posted on: Sat Mar 07, 2009 2:09 pm
Disposable Solid first stage, with a liquid fueled upper stage?


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Post    Posted on: Sat Mar 07, 2009 4:32 pm
Terraformer
4 stage solid. 2 boosters with clusters of 4 motors each booster, firing opposing pairs 2 stages per booster. (makes for shorter rocket) 5th stage hybrid. If we don’t use the gas gun the 6th stage apogee fire's to circular orbit. The problem of not using the gas gun is we can't recover the fifth stage or the apogee stage and that will cost us. But it sidesteps the heavy g load on our satellite.

Monroe

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Post    Posted on: Sat Mar 07, 2009 5:25 pm
i still say that gas gun is brilliant and the g load is overcomable. its worth it just for technology demonstration. of course, i have no idea what kind of materials you can use to make a circuit stick together with that big an impulse but whatever.

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Post    Posted on: Sun Mar 08, 2009 4:50 pm
TerraMs
We are still building the gas gun and we are still looking at it. We just bought a lathe big enough to build it with. We are in the process of getting the lathe down to our tolerances now. (doing some hand scraping) a lot of work. I bought a smaller lathe that is running good right now so we can build other parts. We are open for business to make parts for anyone interested.

Monroe

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Post    Posted on: Sat Mar 14, 2009 6:03 am
I have to agree with Charles and James, both with well more experience than myself, but over the last few months I have been coming up with similar figures. I have been working through an initial optimization process and are coming down to these figures.


Iain


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Post    Posted on: Sat Mar 14, 2009 11:43 am
hahaha great! Sorry Iain I dont see 81kg making orbit. Looks to me like there is a standard error made that makes it look like it will work however I don't have the time to look for it. 3 against one I'm starting to like the odds here. :) Is there anybody elce?

Monroe

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Post    Posted on: Sat Mar 14, 2009 11:49 am
Monroe, are you using an all metal design? Other materials, assuming they can survive the flight conditions, are much lighter and cheaper. The solid rockets in my model rocket are made of cardboard, for example.


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Space Walker
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Post    Posted on: Sat Mar 14, 2009 8:55 pm
Its like Charles said in an earlier post

Quote:
I mean that we each tend to develop an investment in whatever technology, methods we've been studying and are reluctant to abandon it.



If you get time Monroe, you should look into project "Mockingbird", quite interesting, not much info out there on it but if you do a search, you find bits and pieces. Jordan Kare was on the spaceshow on the 2nd March and briefly says something about it. More the fact the size of the components they were going to use which interests me in an N-Prize thinking frame of mind....


Iain


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