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Post by newageofpower on Dec 12, 2016 20:29:23 GMT
Stay tuned people, i've been working on CDE engine nozzle theory and will be posting my findings here shortly. Within a day or two. It's going to take a while to collect all the data; But if my working theory is correct, nozzle design is going to become alot less guess work and more scientific than ever before! My end goal is to turn this thread into a go to place for engine design; So expect alot of editing and reworking on the OP. I can't wait. Also, if you find out that it's impossibru to build an efficient (non-MPD) Mercury thruster, I'll consider the matter closed.
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Post by deskjetser on Dec 12, 2016 20:53:26 GMT
newageofpower One day i'm sure I will have a crack at analysing that for you! For the time being however; My working hypothesis fell flat on the floor, my data is inadequate and worst of all i'm out of coffee! I've got another theory that has stood upto more scrutiny thus far, and i'm starting to build a working model of design around it. It's fair to say though, i'm behind schedule.
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Post by deskjetser on Dec 15, 2016 23:20:24 GMT
Updated OP with my latest work of horror! Appreciate any feedback people, so feel free to criticise.
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Post by amimai on Dec 16, 2016 12:38:08 GMT
Btw have you looked at the relationship between target burn time, exhaust velocity and dV. That is more the deciding factor for my engine design.
For 5-20 sec burn time 90-95% gives best dV because engine mass
For 20-60 sec burn 95-97% gives more dV
For >60 burns 97%+ exhaust velocities are almost always better even if the engine becomes massive
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Post by deskjetser on Dec 16, 2016 13:16:09 GMT
amimai Thanks for mentioning that; Unfortunately i've only dabbled with actual Dv effects for a short while, but i've been planning to do something along those lines. From what I have seen though, in the instances which I have observed, more exhaust velocity is more desirable despite mass increases; The returns for this tail off quickly however, and I have not put any time into mapping the data. I'll certainly move it up on my to do list for the future though!
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Post by deskjetser on Dec 19, 2016 10:54:56 GMT
Just so everyone is aware; I am not going to have time to do any great deal of work improving and adding to this thread over christmas and new year. In the meantime I will be lurking around. Happy holidays people!
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Post by deskjetser on Dec 24, 2016 8:42:02 GMT
Surprise Christmas update!- Added a clearer comparison chart, allowing for better illustration of the ideal angle for a nozzle. (See Further extrapolation segment)
- Fixed my broken math within the NTR synopsis fuel comparison.
Small changes may follow.That's all until after new years. Merry Christmas and a happy new year!
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Post by dwwolf on Dec 24, 2016 11:03:49 GMT
The Astronomer & newageofpower Thank you for making me aware of this. acetylcholine Well you're certainly right about being able to shave off injector weight; But making it smaller would be the incorrect way of doing things! Here is what can be done to greatly improve TMR:- Bumping up the injector radius to 1.2m, decreasing its RPM to 20 and switching to lithium. This will save you a huge amount of weight while maintaining coolant flow of 2.07t/s. - Setting gimbal inner radius to 1.7m to compensate and changing to potassium momentum wheels running at 900RPM. This is all assuming you have a reactor core height of 4.8cm, since you didn't show that in your picture. You can also loose 1kg of control rod mass! Doing this will leave you with savings of 138kg and 100c per engine; And in case I missed anything here is what changes I made. Hope this helps! Got any fried crewmen with nuklear toaster ?
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Post by deskjetser on Dec 24, 2016 11:42:13 GMT
dwwolf you don't like your crewmen crispy? Joking aside; It's more effective to use separate radiation shields, since they are not impacted by the temperatures that NTRs operate at. So you can use materials like lithium-6. Hope this was of help.
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Post by dwwolf on Dec 25, 2016 12:50:43 GMT
Except that the damn thing cant even be built with radiation leakage like that.
It would fry computer hardware as well. And robotic or tele operated construction hardware.
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Post by deskjetser on Dec 25, 2016 15:45:15 GMT
dwwolf well sure, but as of now that is not modelled in CDE afaik.
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Post by newageofpower on Dec 25, 2016 17:55:58 GMT
Except that the damn thing cant even be built with radiation leakage like that. It would fry computer hardware as well. And robotic or tele operated construction hardware. *shrug* put a radshield on your robot. Problem solved.
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Post by dwwolf on Dec 28, 2016 19:00:05 GMT
A megawatt of radiation ? The robot needs to move to be able to work.
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Post by newageofpower on Dec 28, 2016 22:41:19 GMT
A megawatt of radiation ? The robot needs to move to be able to work. 5mm Li6 blocks all the neutron flux. Design your electronics with redundancy/checking ala modern spacecraft electronics for the rest.
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Post by deskjetser on Dec 29, 2016 1:34:08 GMT
dwwolf I perfectly understand your concerns, but until this method of construction becomes nonviable, what do you suggest in the meantime?
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