Sticking another idea into the public domain.

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Sticking another idea into the public domain.

Postby SANEAlex » Thu Apr 11, 2013 7:51 pm

I just posted on spacefellowship forum a reply to something on electric propulsion letting the cat of of the bag one of my ideas that i hoped my team could use in an N-Prize attempt as it is looking increasingly unlikely that we will be able to make a viable attempt before September i thought i would put this bit in the public domain just in case any other team thinks it might be viable as a last stage to their attempt.

http://spacefellowship.com/Forum/viewto ... 287#p49287


If the guys at MIT have got their sums right the EHD toy might eventually become a serious player but as i tend to assume that Lourens has his sums right it might be only when we have viable a broadcast energy system or a huge acreage of spray on efficient solar cells considering the size needed to make it efficient.

http://www.gizmag.com/mit-ionocraft/26908/

Mind you i think it would be quite nice to have huge airships moved by solar powered EHD ion drives which might be one way to make the tech viable. I wonder if this is what JP Aerospace plans to do for propulsion when they get their high altitude airships sorted and in production. I had considered using an inflatable silver mylar Rogallo wing reflecting onto a very thin film or even paint on solar cell with the satellite and ion drive as its counterweight as the final stage of our N-Prize teams entry but as we are still working on the first stage and unlikely to be ready before the competition ends. I thought i would stick this bit out in the public domain as i think as IIRC all the individual bits of this are out of patent and unlikely to be patentable as a whole and it would be nice to see it fly even if i don't profit from it.
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Re: Sticking another idea into the public domain.

Postby pauldear » Sat Apr 13, 2013 11:53 am

It's a cool technology. What worries me, though, is that its effectiveness seems to scale with the size of the object, so you'd need something pretty massive before thrust/payload broke even.

There are also a few cool YouTube videos listed under "electrohydrodynamic thrust", mostly showing small aluminium foil structures whizzing around on the end of tethers that carry the high voltage.

Cheers,
Paul
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Re: Sticking another idea into the public domain.

Postby SANEAlex » Sat Apr 13, 2013 4:11 pm

pauldear wrote:It's a cool technology. What worries me, though, is that its effectiveness seems to scale with the size of the object, so you'd need something pretty massive before thrust/payload broke even.

There are also a few cool YouTube videos listed under "electrohydrodynamic thrust", mostly showing small aluminium foil structures whizzing around on the end of tethers that carry the high voltage.

Cheers,
Paul


I was not envisaging using this as the main source of thrust as it was only recently that MIT worked out the scaled efficiency's

Our partly planned mission profile to do the N-prize goes like this:-

The first stage that we are still trying to work out the details of the patent for and acquire the money to develop from concept to working model would just power up and out this is using the lean bare minimum version with very little need for weighty control and steering mechanisms.

A simple timer could trigger when out of the atmosphere and in fairly hard vacuum(tho we are depending upon some gas molecules which is reasonable as they slow the ISS down) a minimal normal solid fuel rocket either guided by wire or plastic tube(details to be worked out) with what would normally be the parachute release explosive releasing our satellite hanging by conducting cables as the counter weight to an inflatable Rogallo wing partly silvered mylar reflecting onto a very thin PV Solar cell.

I envisaged the satellite to be something like the one built by the wiki sat team without the battery and with the addition of the ion drive long ways possibly part of it duel purposed as an omnidirectional aerial with the kind of capacitor circuit that is or used to be used in car indicator circuits alternately pulsing the ion drive and transmitter.

Code: Select all
       Part Silver Mylar Rogallo wing with pv solar cell 
             power and support cables
               Satellite transmitter
        ----------Ion drive/aerial ------------


The idea being rather than have complex systems to get into orbit the Rogallo wing if it came in to steeply would bounce off via lift from the wing and then fall again and again until it self circularised and hopefully the losses incurred via friction would be compensated for via the ion drive(as there is still gas molecules in LEO) if not entirely at least until we had got 9 orbits above 99km.

Anyway we are still working on the first stage and are unlikely to be ready before the competition ends but will continue anyway as a cheap way into space should be useful anyway. I thought i would put my cheats way of getting something into orbit by self insertion rather than weighty complex control systems into the public domain just in case any other teams might like the idea as a final stage.
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Re: Sticking another idea into the public domain.

Postby pauldear » Sat Apr 13, 2013 4:26 pm

Hmm - I like the idea of a self-circularizing orbit, that's neat!

Cheers,
Paul
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Re: Sticking another idea into the public domain.

Postby SANEAlex » Sat Apr 13, 2013 8:59 pm

pauldear wrote:Hmm - I like the idea of a self-circularizing orbit, that's neat!

Cheers,
Paul


Cheers for not shooting the idea down in flames i think in principle the idea should work but we have not got to practical testing yet ;) :twisted: Its often stated that if you come in a too steep an angle you will either burn up or bounce off so it seems to me that if you use the satellite as counter weight on what is basically a self inflating parachute/glider in its simple form and it has been tested by NASA at supersonic speeds IIRC testing during the Gemini missions https://en.wikipedia.org/wiki/Rogallo_wing . It would if the lift angles were set correctly preferentially bounce off rather than burn up and gradually circularise a steep initially elliptical orbit. It would also have the advantage bringing a payload back down to ground relatively gently if you wanted to use the system for small cube sat types of science projects. I was only thinking of using the more complex doubly inflatable version of the Rogallo wing to gain sufficient solar power from a small cell to power the ion drive which could be necessary with the limitations imposed by the N-Prize rules. I think that with today's modern materials that very light weight versions of the Rogallo wing could be made to do what i suggest or have i missed something obvious :?:
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Re: Sticking another idea into the public domain.

Postby pauldear » Sat Apr 13, 2013 9:20 pm

I don't know enough to comment on the technical problems, but I wonder what the efficiency of the EHD is? I guess it should be pretty high, inasmuch as if you get all your ions going in the right direction, there's nowhere for the electrical energy to go except into propulsion.

To me, the main problem is that this sort of system (both EHD and atmosphere-bouncing) is very difficult to test and optimise, since it all depends very heavily on interactions with a very thin atmosphere at high speeds. In contrast, high-impulse methods (ie, traditional rockets and the like) can have their behaviour predicted fairly closely, and ground-based tests give you a lot of useful data.

Overall, I very much like the idea of "flying" a spaceship as close as possible to the edge of space, especially if solar power can be used (a kilowatt per square metre - npt a lot but significant). I'm by no means qualified to evaluate possible schemes, but flying is a fairly gentle, manageable technology which, if you scale the velocities as the atmosphere thins (reducing lift per unit speed, but at the same time reducing drag) ought to get you a long way.
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