Quote from: Jim on 07/17/2012 02:17 amQuote from: clongton on 07/17/2012 02:06 amQuote from: Jim on 07/16/2012 11:35 pmCan't take the spinup and scuffing from landing.Simple. Armature built into the hub. Just before touchdown, spin it up to landing speed. Automatically initiated by ground proximity.Thinking outside the box.You think wings are useless in space? I do.
Quote from: clongton on 07/17/2012 02:06 amQuote from: Jim on 07/16/2012 11:35 pmCan't take the spinup and scuffing from landing.Simple. Armature built into the hub. Just before touchdown, spin it up to landing speed. Automatically initiated by ground proximity.Thinking outside the box.You think wings are useless in space?
Quote from: Jim on 07/16/2012 11:35 pmCan't take the spinup and scuffing from landing.Simple. Armature built into the hub. Just before touchdown, spin it up to landing speed. Automatically initiated by ground proximity.Thinking outside the box.
Can't take the spinup and scuffing from landing.
Quote from: clongton on 07/17/2012 01:51 pmQuote from: Jim on 07/17/2012 02:17 amQuote from: clongton on 07/17/2012 02:06 amQuote from: Jim on 07/16/2012 11:35 pmCan't take the spinup and scuffing from landing.Simple. Armature built into the hub. Just before touchdown, spin it up to landing speed. Automatically initiated by ground proximity.Thinking outside the box.You think wings are useless in space? I do.They are useful for catching orbital debris and micrometeors on the TPS.;-)
Err... lifting bodies have more internal volume, they are "fatter". The Shuttle had wings because of cross range consideration. Read the history of the discussions.
The environment for the Shuttle tires (conventional aircraft tires inflated with nitrogen) was considered fairly benign. The X-37 uses smaller but otherwise similar tires with 300psi inflation pressure. It had one tire blowout on the first landing but otherwise no problems. Regarding wings, I realize people have their preferences and aerodynamics may not generate a lot of interest. But the X-37 wings provide a much higher lift to drag ratio than the Dreamchaser's wingless lifting body shape and because it depends much less on body lift the X-37 can utilize a more efficient fuselage shape, with more internal volume, less structural mass, and less internal stress when pressurized. In fact this is why after decades of work with lifting bodies NASA decided to use wings for the Shuttle. However I think the X-37 has a significant advantage over either the DC or Shuttle because of the long moment arm between its V-tail surfaces and the center of pressure, giving it greater tolerance for CG location (always a concern with the Shuttle) and much better pitch control when landing in variable or suboptimal winds, which often present themselves.The question of wings vs parachute for landing is not a matter of mass, but of cost. A winged vehicle is easier to make fully reusable because there is no need for portions of the vehicle to be dropped (i.e. the heatshield for the CST) or deployed and refurbished, like the parachutes. The actual energy (i.e. fuel) to lift the wings into space costs almost nothing, and the X-37 of course had no foam fragments to damage its thermal tiles. For a given booster lift capacity, a capsule will have more payload mass and volume than a runway lander, so as long as the booster is thrown away the capsule will have a cost or payload advantage. But if and when fully reusable boosters are available the initial booster cost will have little impact and one can simply choose a slightly larger booster. The easier reuse of the runway lander will then be a significant advantage.
The environment for the Shuttle tires (conventional aircraft tires inflated with nitrogen) was considered fairly benign.
Regarding wings, I realize people have their preferences and aerodynamics may not generate a lot of interest. But the X-37 wings provide a much higher lift to drag ratio than the Dreamchaser's wingless lifting body shape
and because it depends much less on body lift the X-37 can utilize a more efficient fuselage shape, with more internal volume, less structural mass, and less internal stress when pressurized.
In fact this is why after decades of work with lifting bodies NASA decided to use wings for the Shuttle.
However I think the X-37 has a significant advantage over either the DC or Shuttle because of the long moment arm between its V-tail surfaces and the center of pressure, giving it greater tolerance for CG location (always a concern with the Shuttle) and much better pitch control when landing in variable or suboptimal winds, which often present themselves.
The question of wings vs parachute for landing is not a matter of mass, but of cost.
A winged vehicle is easier to make fully reusable because there is no need for portions of the vehicle to be dropped (i.e. the heatshield for the CST) or deployed and refurbished, like the parachutes.
The actual energy (i.e. fuel) to lift the wings into space costs almost nothing, and the X-37 of course had no foam fragments to damage its thermal tiles.
For a given booster lift capacity, a capsule will have more payload mass and volume than a runway lander, so as long as the booster is thrown away the capsule will have a cost or payload advantage. But if and when fully reusable boosters are available the initial booster cost will have little impact and one can simply choose a slightly larger booster. The easier reuse of the runway lander will then be a significant advantage.
Wings versus parafoil is absolutely a matter of mass. A large portion of an aircraft's mass lies in the wings, especially one that's supersonic (or hypersonic). The main spar is quite heavy, and the control mechanisms aren't light either. The gear gets heavy when the high-speed landing is figured in, and the main spar gets heavier with the heavy gear. If the wing is wet, not the case here, the spar gets even more massive, not to mention the weight of the tanks. The X-38's parafoil was very much a way to achieve a lower stall with less mass.Max Hunter's observation was that the wings were such a major portion of a spacecraft's weight that by leaving the wings off, one could carry so much extra propellant that vertical landing was possible.QuoteA winged vehicle is easier to make fully reusable because there is no need for portions of the vehicle to be dropped (i.e. the heatshield for the CST) or deployed and refurbished, like the parachutes. Here again that's the opposite of what's true. A single center of forward pressure is far simpler to protect than a collection of leading edges and a belly, along with the gear and tires. That's why capsules really are easier.