Will the prize be won?

yep your right i was miss using the term and did not think of using the better mass ratio.

I was trying to get across that in the normally used liquids and solids used, liquids have a better isp than solids but the complexity's of manipulating the liquids adds a weight penalty to your mass ratio that is proportionate to size.

This is probably a more accurate and concise way of saying it after your help with proof reading.

And although there are explosive solids both chemical and fissile that may well give better isp than traditional liquids i suspect that they would need a considerable weight penalty for safe containment reducing their otherwise better isp again very much proportionate to size..

I love this place so much.

What about energy densities of the fuel?

Would that be enough to estimate the minimum size of a rocket?

I mean for a given mass you need a certain amount of energy to reach orbital velocity. So doesn't that mean that with any given fuel and method of turning it's stored energy into kinetic energy of the rocket, you would have a minimal size constrain below which you cannot go because the fuel you can have on board /determined by the size/ will not have enough energy stored in it to be turned into enough kinetic energy to overcome drag and other losses and reach orbital velocities.

Bare with me, my math and physics sucks and its late:

So one kilogram /497.5 mol/ of hydrogen burned with oxygen releases 286 kilojoules/mol X 497.5 mol = 142285 kilojoules.

Kinetic energy needed for one gram of payload to LEO:
DeltaV for LEO is around 9.4 km/s, that translates into
0.5 x 1 g x 9400^2 m/s = 44180000 joules that's 44180 kilojoules.

So on paper so far 1 kilogram of hydrogen and 0.5 kilogram of oxygen should have enough energy stored in it to put 1 g of payload into orbit. The problem is all the losses along the way. But without losses a fairly small sized ideal rocket could do it.

So it seems the majority of the problem isn't getting energy, it is avoiding losing it along the way on other stuff than adding to the kinetic energy of the payload.

So then it is the size of the engineering in place to avoid losses that constrains the size of the rocket.

Am I on the right track here or I completely screwed up.

Its late i should be sleeping

Darn i just posted this then i realised that if we assume an SSTO design and if we ignore any atmospheric drag, gravity losses etc...then the dry mass of this rocket would have to fit into the 3.22 grams the energy stored in the fuel can potentially take to orbit.

It would be a very light rocket. LOL

Yeah i think i am getting a better grasp of this now. If my calculations were correct so far, it seems the major constrain of minimum size is the properties of the materials used to build the rocket. Things like density, ability to withstand strains of and tension of all sort, ability to withstand high temperatures...

So the energy density of the fuel is a factor, but it seems the hydrogen oxygen reaction releases plenty of energy, it's just you can't handle that and turn it into kinetic energy below a certain size (mass, complexity, spacial dimensions). Well it all depends on the materials you use.

Idea for solid rocket motor:
The container wall itself combusts as the fuel combusts.

It's kind of like staging, except you stage gradually.

So basically you burn-stage. You burn all the excess mass you don't need anymore on the rocket.

Anybody tried this before?

Well i have 143 MJ as the theoretical maximum for burning H2 in air so you seem to me to be in the right ball park.

My pet chartered chemist tells me burning pure H2 and O2 together in the real world you never get a 100% burn so you cant extract all that energy however if you use air the nitrogen gas acts as a chaperone molecule for the reaction enabling 100% burn but in the real world you get some nox products as well the clean water steam.

Here is the the four main things that i have identified that cause losses that prevent that nice simple equation happening.

Air resistance a biggie that's why lots of Nprize people are planning rockoons.

Gravitational losses you have to overcome 9.8 Newtons just to stay still for every kilo of mass for every second you are in flight.

Mass of the vehicle that is not useful payload that contains and controls the burning of the fuel.

And a nasty recursive one mass of fuel needed to lift the mass of fuel used higher up.

Sleep what's that i stayed up early for the transit of Venus but misunderstood the timings it is tomorrow morning where i am oh well i will prob sleep well sometime on Wednesday.

So the more axceleration you do early on less fuel you will need to lift higher. But then more drag you will need to overcome. Then the higher you launch from and the sooner you achieve orbital horizontal velocities the less gravitational losses you will need to deal with. I mean if you just let the rocket fall and put most or all the energy very fast into horizontal motion. So depending on the angle of launch you get either faster out of the remainder of the atmosphere but have to accelerate more against gravity, or you spend longer in the atmosphere but then you are working against drag.

So how about a shark skinned rocket fish with 100 stages that burn as fast as possible, then when the last stage reaches apogee it circularises the orbit and we are done. Its more like the merging of a gun and a bullet. The skin is to help with drag.



I mean each stage is a kind of barrel that blasts itself off from the rest as the fuel explodes the exhaust is not let out the back. Kind of like the nuclear bomb rockets. I guess we can view it as lots of small rockets shooting away backwards from our rocket.




Talking *** on the way to work, so much fun.

It's interesting that there has not been any discussion on this forum about the Brazilian team, NTA. According to Paul Dear on the N-Prize forum, they have announced that they will do an N-Prize attempt on July 29. There is some information about this in Portuguese on http://brazilianspace.blogspot.com.br/2 ... prize.html

If I understand the English translation correctly, they intend to fly a balloon to 70 km, launch a rocket to 100 km and fire a small cannon containing 150 ml of alcohol and oxygen. Considering that the current balloon altitude record is 53 km, it seems that their appoach is a bit aggressive. 150 ml of alcohol contains much more energy than 20 grams traveling at orbital velocity. However, I would think it would be very difficult to build a cannon that could accomplish this feat.

Well the shark skin analogue could help with turbulence but you would still have to expend energy pushing a 100Km of atmosphere out of the way.

So you are taking about using a 100 shaped charges of the best explosive to mass ratio where when you set of one charge it cleans out the stage totally giving as much push as possible against the atmosphere below as well as its more traditional rocket thrust aspect and then setting of the next stage when the atmosphere has collapsed back in.?

Well good luck with getting that past the health and safety guys and also getting your hands on the best explosives in the toy cupboard governments tend to be a bit propitiatory over that kind of thing and wrap it in lots of red tape.

I think control might also be a problem even with slanted fins.

But on the devils advocate i take no responsibility whatsoever. I have a vision of a balloon launch one of these built with the following construction technique.

Starting at the top have your payload then a buffer copper disc then the best explosive you can get done as a shaped charge around a parabolic hollow copper slug surrounding the hole in the copper washer below the copper washer "painted" with thin layer of thermite each side then the best explosive you can get done as a shaped charge around another parabolic slug surrounding the hole in the copper washer below done a hundred times then wrap the whole thing in carbon fibre with using aluminium oxide as the filler for the best heat resistive resin you can get to hold it in place and score holes in the carbon fibre around each copper disc to cause weak points then fill them in with a soft resin and polish smooth spray with very thin resin layer and imprint it with the lotus flower surface pattern(your shark skin thing but biomimetics that has already been done).

Long slow fuse connected to bottom stage light blue touch paper release balloon and stand well back.

I hear by open source this idea but don't hold me responsible for any missing fingers thumbs or craters caused by misapplication of it.

I don't think any of the team have registered here? and my Portuguese is not that good i think the extra height could be done by heating the gasses in the balloon at a certain height then dropping the heater and on the cannon its going to be a one shot one so it does not matter if the cannon survives as long as the payload is moving ahead of the destruction of the cannon.

SANEAlex:
I was thinking of a balloon launch as well, though it would be interesting to see one launched from the ground.

Maybe one day when I am rich I can throw some money at it and see a big bang and lots of smoke as it all just explodes. LOL

As it is basically a swords into ploughshares kind of thing as in its each stage is a slight modification of a tank buster skeet where they turn a parabolic copper slug into plasma lance that cuts thru tank armour like a hot knife thru butter you probably don't want to stand anywhere near underneath it if it were launched from the ground hence the caveats of i bare no responsibility but launched from height the copper might disperse as fine droplets if it were designed to do so and still give effective thrust. But as i say i am doubtful about the government's that have access to the most advanced kind of explosives allowing those kinds of toys to be used in the way i suggested.

Well folks I've been very busy for some time now. Working on guidance and HIL simulation. Haven't been playing around for some time. We just got a big break and are about to make an announcement should be around 10pm PDT. We are about to be supporting another group and using what we have learned over the past 6 months or so to help them. As well as help our-self's get over the first hump.

It's been a great 6 months and I'm ready to get some hardware in the air.

Monroe

Today's the Day!

The problem with figuring out which configuration would work is that you don't know until you try. You can have a perfect fuel, a perfect rocket, and perfect software on paper, and then you put it together, and you get instant confetti. That's why you have to experiment to see what works and what doesn't - first with something imperfect, but simple, and then once you get that to work, and you are a little bit experienced, you try to figure out how you can make it better.

Rumours that it has been extended another year but only for teams that have already signed up

The deadline for signing up is September 19, and the "final" deadline for winning the N-Prize is one year from that.

And for those still in the game CL-20 might make a good one shot cannon explosive if anybody can get hold of a free sample and not end up wearing an orange jumpsuit.

http://www.gizmag.com/cl-20-high-power- ... ive/24059/