51–60 of 78 posts
BPS.space is attempting it. Test Launch: https://www.youtube.com/watch?v=QQt-9SSJ51c Test Landing: https://www.youtube.com/watch?v=lXy-x6lkQvQ
Wow, close! This appears to be working with solid rocket motors, thrust vectoring, and a carefully timed ignition. How do they get accurate distance to ground? Is altitude just a constant for these tests?
BPS.space is attempting it. Test Launch: https://www.youtube.com/watch?v=QQt-9SSJ51c Test Landing: https://www.youtube.com/watch?v=lXy-x6lkQvQ
Ah wow I watched a bunch of his videos last summer but forgot to check up on his progress. Incredible! I wonder what scale you would need to get the rocket into space/orbit? SpaceX should fund this guy to find out, could prove to be a valuable bootcamp for real SpaceX employees in the future?
There's a great "what if" xkcd about using solid fuel model rocket engines (the same type used in BPS.space's rockets) to get to space and orbit.
The summary is that you may be able to use a stupendously large number of them to get to space, but orbit is physically impossible. You'll need a different propulsion method.
The smallest rocket that has ever carried a payload to orbit is the SS-520. It's ~30 feet tall, ~2 feet in diameter and weighs ~5,700 pounds. It set the record in February 2018, so it's a pretty recent record.
You will blow up several engines if you try to make a liquid fueled engine. Get yourself a copy of https://www.amazon.com/Rockets-Missiles-Men-Space-Definitive... which is the story of a German rocket club which first got shut down by the Nazis because "somebody could get hurt" and then the Nazis thought it over... Probably your best bet is a hypergolic monopropellant such as hydrogen peroxide.
Trying to buy high test hydrogen peroxide (high concentration) might well get you flagged by the police as its used in bombmaking
But from previous research it sounds really simple to concentrate (up to 70%) if you can acquire enough low concentration hydrogen peroxide. So much so that it kinda scares me that I have a bottle of 3% hydrogen peroxide in my house.
Edit: Again, this is a bad idea, but here's the title of my source: Methods for Concentration of Hydrogen Peroxide To Obtain It in Anhydrous Form
It's likely to be difficult. I heard a good analogy once: imagine balancing a broom, handle pointed straight down, on one fingertip. It's not that hard. Now imagine balancing a toothpick. Impossible. Scale matters. Bigger things are more stable.
Specifically, you need reaction time faster than sqrt(l/g), where l is the distance between the engine and the center of mass, and g is gravity. But l=30 cm is still with the range of commodity hobby servos to vector the engine. The same effect makes walking robots harder at small scale, unless they cheat by having large feet and stiff ankles.
Be really careful. Adding guidance to a hobby rocket may classify it as a missile, and you will need to start looking into ITAR.
Not an american, but I thought ITAR just restricted export (including of information though), hence the I(nternational) and T(rade)?
BPS.space is attempting it. Test Launch: https://www.youtube.com/watch?v=QQt-9SSJ51c Test Landing: https://www.youtube.com/watch?v=lXy-x6lkQvQ
Earlier quoted context omitted.
I was actually curious how cruise missiles were defined in itar. The definition of missiles is really broad and actually includes lots of UAVs. > “Missiles”. (All) Rocket systems (including ballistic missiles, space launch vehicles, and sounding rockets) and unmanned aerial vehicle systems (including cruise missiles, target drones, and reconnaissance drones) “capable of” delivering at least 500 kilograms payload to a…
> The definition of missiles is really broad...delivering at least 500 kilograms payload to a range of at least 300 kilometers. Not as broad as I would have thought. You could do a lot of damage with 499 kg of TNT, and nuclear bombs weigh less. Little Boy was 64 kg of uranium according to [0]. [0] https://en.m.wikipedia.org/wiki/Little_Boy
Or the W54 was reputedly much lighter, but with a larger diameter.
Earlier quoted context omitted.
I was actually curious how cruise missiles were defined in itar. The definition of missiles is really broad and actually includes lots of UAVs. > “Missiles”. (All) Rocket systems (including ballistic missiles, space launch vehicles, and sounding rockets) and unmanned aerial vehicle systems (including cruise missiles, target drones, and reconnaissance drones) “capable of” delivering at least 500 kilograms payload to a…
> The definition of missiles is really broad...delivering at least 500 kilograms payload to a range of at least 300 kilometers. Not as broad as I would have thought. You could do a lot of damage with 499 kg of TNT, and nuclear bombs weigh less. Little Boy was 64 kg of uranium according to [0]. [0] https://en.m.wikipedia.org/wiki/Little_Boy
Earlier quoted context omitted.
> The definition of missiles is really broad...delivering at least 500 kilograms payload to a range of at least 300 kilometers. Not as broad as I would have thought. You could do a lot of damage with 499 kg of TNT, and nuclear bombs weigh less. Little Boy was 64 kg of uranium according to [0]. [0] https://en.m.wikipedia.org/wiki/Little_Boy
The fissile core is a tiny part of the weight of a nuclear weapon, though. Little Boy weighed almost 10,000 lbs; it took a lot of explosive, metal, and circuitry to detonate it.
A gun-type bomb doesn't require a very complex system to set it off. The complicated bomb was Fat Man, an implosion bomb, that required very precisely calculated explosive lenses and precise timing circuits.
Earlier quoted context omitted.
Specifically, you need reaction time faster than sqrt(l/g), where l is the distance between the engine and the center of mass, and g is gravity. But l=30 cm is still with the range of commodity hobby servos to vector the engine. The same effect makes walking robots harder at small scale, unless they cheat by having large feet and stiff ankles.
How did you get the sqrt(l/g) figure? I can see how this is dimensionally correct and passes a sanity check, but why is the coefficient one?