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SpaceShipOne Flight Test
Soft writes "Scaled Composites' entry for the X-Prize, the SpaceShipOne, has had a successful first (unpowered) flight test.
The spacecraft was dropped from the White Knight carrier aircraft at 47,000 ft (14 km) and 105 kt (194 km/h, 120 mph) and touched down after a 1.1-hour glide at Mojave airport.
Photos are available."
Flight Time: 1.1 hours / 19 minutes
The post refers to a 1.1 hour flight, which shocked me as a rather long glide from 47,000 feet, but after reading the article it seems that total flight duration was 1.1 hours and actual glide time was a more understandable 19 minutes. 19 minutes is still great from that altitude as Nasa's shuttle has a much higher sink rate, despite its greater weight.
Re-entry from orbit involves hitting the atmosphere at almost-orbital speeds - about 17,000+ mph.
SSO is designed to fly SUB-orbital. Its re-entry will be MUCH slower. Scaled Composites' website quotes a maximum speed of about 2,500 mph. Kinetic heating shouldn't be a major problem at that sort of speed.
in this case, 10 nm means 10 nautical miles, not 10 nanometers.
A nautical mile is slightly more than a mile ( I forget the specifics), but 10 nm is roughly 11 miles.
Spacedev completed the last and full scale test of it's rocket motor for SpaceShip One last week. So, it has a way go up now. Here's the link...
SpaceDev Performs Successful Rocket Motor Test
nautical mile A unit of length used in sea and air navigation, based on the length of one minute of arc of a great circle, especially an international and U.S. unit equal to 1,852 meters (about 6,076 feet). Also called sea mile.
Since aeronatical charts have hash marks for each minute of latitude along the north-south lontigude lines, it is easy to pull nm distances off using ruler that are corrected for the map's distortion due to projection.
The amount of fuel necessary to do this would be completely impractical, comparable to the amount of fuel needed to launch the orbiter in the first place. It's *far* more efficient to use the atmosphere to slow down.
First, the X-price is about creating a sub-orbital craft, not an orbital one. Still, it's a valid question you ask.
Rockets to slow the capsule / spaceship down for rentry purposes has been used on every single manned spaceship I know of. They are called retro-rockets and are employed to initiate re-entry at the proper time and place to put the capsule / spaceship down where it's supposed to come down. The alternative is to stay in orbit until it dacays naturaly, and then who knows how long you will stay up there or where you will come down.
That said, I assume you knew that already and are wondering about rocketengines / other engines that can be used continualy for a logner period of time to brake the craft faster than purely aerodynamic braking can achive?
In theory it is nothing stopping you from trying that - apart from the weight of both engines and fuel. Not only does the rule of thumb tells us that for every kilogram you want to take into orbit, you'll burn ten kilograms of fuel to get it there, but as the engiens and fuel will have to be protected against the heat of re-entry, you nead a larger (thus heavier) heatshield as well as a larger (heavier) craft overall. And that in turns means - you guessed it - that you'll have to burn even more fuel getting it up there.
On the other hand, if you're simply suggesting dropping the relative groundvelocity of the craft to zero before it re-enetered the atmosphere, so it would drop straight down, I see two problems. Firstly, you would have to do it fast (since loss in speed means loss in altitude - thus meeting the atmosphere), which means an allmighty kick in the pants for the poor astronauts (very hight G). Secondly, the heatpulse would be about the same anyway - the craft will have a whooping huge potential energy from simply beeing that high, and that will be converted to kinetic energy (read; speed) on the way down. Remember Epot = mgh while Ekin = 1/2mv, and if we assume that all the potential energy is transformed into kinetic energy (which it ain't, a whole lot will turn into heat), we find that Epot = Ekin, thus mgh=1/2mv. Simplify, and you see that the speed (v) equals the square root of two times the height multiplied with the gravitatinal pull (v=sq(2gh) ). Thus, if we set the height to 100 km (100000 meter) and we assume that g is constant at 9.82ms, we find that the speed of the craft as it reaches the surface is no less than 1401.42 meter a second, equal to 5045kmh, equal to 3136mph, or about 4.25 Mach. So to summarise, you won't save anything by 'stopping' in your orbital tracks.
Everything in the world is controlled by a small, evil group to which, unfortunately, no one you know belongs.
Starship.
Not quite true.. good math but it forgets that once you do begin dealing with the atmosphere the aerodynamic drag vrs gravity will create a terminal velocity ( ie the reason a feather and a brick dropped from a hight don't hit the ground at the same time ) so it will not continually accelerate all the way down to a smoking hole in the dessert. Also once it encountered enough atmosphere it would go from a falling rock to a flying glider which would allow greater control in the descent and you could trade some of that potential energy for lift instead of speed.
Course decelerating with rocket engines means you need essentially the same amount of fuel as it took to launch. IE if you wanted to slow the shuttle down to nill in orbit for re-entry you would need the SRB's and ET full of fuel for the deorbit burn. You would need slightly less due to the greater efficiency of the engines in vacume but not enough less to matter. so due to the fact you can't lift more payload than fuel weight its not possible to launch with enough fuel for this scenario. If you could re-fule on orbit it might proove more feasible... IE if we captured an icy asteroid and broke the water down into H2 and O2 you could create a gas station in orbit... though if we did that the fuel would be better spent leaving earth orbit than it would for landing.
I submitted the report when they were first test flying the White Knight, with the space plane strapped to the belly.
Test flights are test flights, and the space plane neither went orbital or even to the edge of space. It was dropped from the bottom of the White Knight.
Hence my cause for bitching. I submitted several reports of relevence, and not one has been approved (the space flight report was rejected scant seconds after submission).
And similarly, my complaint is on topic, since it covered the above story months earlier. If anyone actually cared (no thanks to mods with itchy trigger fingers and too much time on their hands, yet not enough to actually read the article either), they'd note that the first test flight for the launch platform was successful, and within 4 months the space plane was being tested, leaps and bounds ahead of NASA in terms of speed and R&D.
Just because you can mod me down, doesn't mean you're right. Shoes for industry!
Maybe this is a stupid question, but could you reduce the amount of heating during rentry by slowing the craft down much much more before it reenters?
Funny you ask. SSO has a unique design in which the wings fold during re-entry and provide an aerodynamically stable "shuttlecocking" effect such that the belly remains down. This means more drag at higher altitudes, simpler re-entry controll, etc. Then the wing converts pack and the pilot glides the vehicle in. More drag at higher altitudes also means that it is decelleration is more spread out, so the heat (potential energy -> kenetic energy -> heat) is applied at a slower rate and is less of a problem.
It is all there in the FAQ.
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