El Reg's plucky Playmonaut eyes suborbital rocket shot Those of you who like your rockets liquid-fuelled and your altitudes suborbital might like to have a shufti at "Earendel", which promises to be "the first vehicle capable of reaching space, ie, greater than 100km, with an entirely open source design". Cutaway view of the Earendel rocket Earendel (left) - named for the Anglo- …
It's going to be picked up a long way away when it is travelling slowly, and the payload is minuscule (unless you are suggesting Hamas is making warheads from old smoke detectors.)
The worst small weapons to deal with are low altitude flat trajectory; fast, hard to see coming. Think Exocet, the WW2 German 88mm gun, cruise missiles and low level fighter/bombers.
Exocets are slow. They're subsonic. http://en.wikipedia.org/wiki/Exocet
The FLAK/PAK 88 was a good gun for its time, but that time is long past. Modern tank weapons are much better.
The Exocet is a cruise missile. Most cruise missiles are slow.
Low level fighter-bombers are also usually subsonic because it's dangerous to go too fast too low.
@Wolffan
Obviously I was referring to these at the time they were in use militarily, and were difficult to counter.
Also, "slow" is relative. If the Palestinians had a choice between a home made cruise missile that could do 300kph at a few tens of metres, and a human being on foot with an explosive vest, I suspect they would go for the cruise missile, not complain that it wasn't supersonic.
You can trade paylod for range, and you can still launch it with a different trajectory.
The german 8.8 gun was designed as an AA gun (and later found its way as an antitank one), which does require a "straight" trajectory (and thereby an high muzzle speed) to be effective. Long range guns don't, otherwise they would be limited by obstacles and earth curvature. Antiship missile take advantage of the sea being almost flat and surface waves not being radar friendly. Their terrestrial counterparts need to fly higher, often slower, and with a fairly more complex guide system to deal with the more complex environment. Most unguided rockets simply use a ballistic trajectory because it's the simplest to get past most obstacles at high speed.
Low level bombers were a big bet in '70s and '80s strategies - but in the first Gulf War they demonstrated to be very vulnerable to plain old AA artillery barrage fire. After many Tornados were downed, the allied forces switched to medium altitude bombing. Guided bombs and stand-off ones gave better result when air superiory is established and medium/high altitude SAMs are already disabled/destroyed, or taken care by elecronic warfare and SEAD teams. Today, more effort is put in low visibility and electronic warfare to blind/deceive enemy sensors than just flying low and fast.
It is still true it may be far easier to infiltrate a single low flying plane, but an unamanned one would require far more complex technology, or remote control, not easy to achieve BVR without a powerful enough radio transmitter - or using some for of repeaters.
Anyway, I don't find very sensible to detail some "open source rocket science" in these times.... ok, it's secret matter, but helping mad people with ready to made components looks a bit silly to me.
lucifer (originally heylel - light bringer, shining one or morning star and a name for the planet venus) is a catch-all term for those who were considered to be particularly close to god, and in fact jesus was specificaly referred to as lucifer at one point in the bible.
satan is called lucifer in modern times because he was originally supposed to be gods right hand man prior to his fall, a story not actually contained within the modern christian bible. satan is never actually referred to as lucifer in the bible and the text which christians point to to say that he was is in reality a sick burn on the old king of babylon.
can't help thinking that it's not going to help the space junk situation. Maybe not this project, but one like it and soon
Probably not this one, and probably not for a good while. To be a proper space junk problem you need to be leaving stuff at the orbital height of the ISS (400km) or higher. Below that, the junk drops out of orbit fairly fast and there are not many satellites for it to break, because they too would drop out of orbit rather fast.
Once people start building amateur rockets that leave junk around at 700km, that will be a very serious problem as it takes ages for the junk to fall out and there is lots of expensive hardware for it to mess up (including the satellite I have been working on for the last decade). I am not actually a rocket scientist, but I get the impression that reaching 400km and leaving stuff there is a whole different game from reaching 100km.
There is a HUGE difference between getting up to 100Km and falling back vs. getting up to 100Km and staying there in orbit.
Wikipedia suggests you can do the former with about 1.4Km/s of delta-v, the latter requires over 9Km/s.
It will be a while before a cheap amateur rocket can deliver 9Km/s to a payload of any size.
Getting to the minimum practical height for a circular orbit requires an input speed of 7.9KPS. You get to an elliptical orbit at 8.3KPS, and can break out of orbit with an imparted velocity of >11.3KPS
However, all of these speeds are based on high burn rate chemical rocketry that rely on you throwing a huge amount of thrust in at the start and then coasting the rest of the way on the imparted momentum. Future made at home devices will probably be multistage rockets with chemical stages to get you high enough up for an ion thruster to run.
Improbable and impracticable at the moment, yes. However, if you'd have told somebody 30 years ago that you were going to build a rocket that was going to get to 100KM out of your pay packet from commercially available materials then you'd probably have been thought insane.
As anyone who has worked with liquid nitrogen cooled apparatus in a university physics or chemistry lab should be able to attest, distilling liquid oxygen from air is trivially easy if you have a ready supply of liquid nitrogen, a length of tubing, and a vacuum pump.
Vacuum distillation lines routinely use a nitrogen cooled trap to catch any volatiles before they end up in the vacuum pump's oil sump. One has to be careful not to open the other end of the line to the air, or you can end up with LOX in the trap, which is hazardous in its own right, but downright dangerous if mixed with any trace organics there might be already in the trap. A case of, "what's this pretty blue liquid?" followed by BOOM!
Liquid fueled rockets are not necessarily easy to build, and even harder to control. An alternative approach, using a hybrid liquid/solid fuel design has some advantages. One such rocket, based on asphalt (Yeah, the same stuff they pave roads with.), and Nitrous Oxide (Hehehe!) has been flown successfully:
http://www.asi.org/adb/06/09/03/02/106/halo-launch.html
As for anyone attempting this in the USA, be aware that there are some VERY serious regulations that the FAA and State Department have for flying such rockets Special approvals (e.g., waivers) must be obtained well in advance of the flight, as well as notifying Air Traffic Control (ATC) centers of the impending launch, flight, and disposition of the vehicle, just so that no airliners happen to be in the flight path. And, failure to follow those procedures can subject one to some rather incredible fines, imprisonment, as well as some serious probing.
But, otherwise, keep reaching for the stars.
Dave
P.S. Oh, yeah, make sure you know where the closest burn treatment center is located, and have plotted the quickest route to it.
props for including the mythical F19 stealth interceptor. Many oddities would have done there
When I was much younger than I am today, four of my cousins and I were mad for model rockets. We first used commercial solid fuel motors, but they cost too much and we started making our own, using home-made black powder, first flour powder, then corned powder. We later souped things up with nitro compounds. After a while that was too tame, so we tried for a liquid-fuel rocket. We had problems with the ignition, so we elected to go with a hypergolic mix: hydrazine and red fuming nitric. Getting the hydrazine was non-trivial. Getting the nitric was easy; we merely 'borrowed' some from our high-school chemistry lab. The first (and last) time we did a flight test, the rocket blew up on the pad, showering our 'blockhouse' (a garden shed reinforced with concrete blocks, and a zinc roof) with pieces and small amounts of nitric. The nitric ate holes in the zinc roof. The parents were Not Amused at discovering what we had been up to.
We should have died many times over, starting when we were making the flour gunpowder, but especially when were playing with the hydrazine and the red fuming nitric. On the plus side, I still remember how to make guncotton and nitroglycerine.
Don't forget the open source space adventure Copenhagen Suborbitals who want to send a human above the Karman line in a suborbital flight. They have already launched some serious rockets, have a lot of interesting youtube footage and recently their English language web site has improved significantly:
http://copenhagensuborbitals.com/
Sometimes they do some impressive rocket engine tests that are well worth attending. Only a cheap flight to Copenhagen is needed.
Nutter's Law explains why we don't hear from aliens much:
C = E x P x N x Ks, Where:
C= Chance of a civilisation being ended
E= Ease of mass killing. (i.e. how easily an individual might cause mass murder)
P= Population
N=Fraction of the population who believe mass murder is a solution to something
Ks=Fudge factor to paper over my lack of maths
Not sure if this device is on the road to nudging up E at some point but sci/tech has certainly made a big contribution already! I do consider N to be smaller than the media would lead you to believe. Fingers crossed.
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