Nibb31 Posted April 17, 2018 Share Posted April 17, 2018 (edited) Not sure what you mean. Capsules are also lifting bodies. The only difference is that they use RCS for control instead of control surfaces. Operationally, DreamChaser is a capsule with a slightly higher L/D ratio and a lot of extra weight due to the wings stabilizers, landing gear, and hydraulics, which are only used during the last minutes of its mission (which is primarily to fly in space). In practice, the Space Shuttle experienced around 3G deceleration. Due to the lower surface area, DC will probably come in a bit hotter, say 3.5G. Soyuz goes up to 5G for a short period. A modern lifting body capsule should peak at around 4-4.5G coming in from LEO. Another advantage of a capsule is that it can re-enter passively if necessary. If it loses control authority, it will stabilise into a passive attitude, you will get more Gs that way, but as long as you can pop the chutes manually and you don't get eaten by lions, you should survive. From LEO at least. If a lifting body loses hydraulics or power, you're toast. Lower Gs are preferable of course, but the difference isn't huge and the mass and complexity penalty is high. Edited April 17, 2018 by Nibb31 Quote Link to comment Share on other sites More sharing options...
YNM Posted April 17, 2018 Share Posted April 17, 2018 9 minutes ago, Nibb31 said: Operationally, DreamChaser is a capsule with a slightly higher L/D ratio and a lot of extra weight due to the wings, landing gear, and hydraulics, which are only used during the last minutes of its mission (which is primarily to fly in space). Good to know it has "wings" then. Quote Link to comment Share on other sites More sharing options...
Nibb31 Posted April 17, 2018 Share Posted April 17, 2018 Just now, YNM said: Good to know it has "wings" then. wings stabilizers Quote Link to comment Share on other sites More sharing options...
YNM Posted April 17, 2018 Share Posted April 17, 2018 Yeah... But whatever, as long as they can return the space beansprouts home safely. Quote Link to comment Share on other sites More sharing options...
kerbiloid Posted April 17, 2018 Share Posted April 17, 2018 (edited) These wings stabilizers have elevons, flaperons or so Spoiler Can they fold/extend? Can it fly itself from runway to runway if mislanded? Edited April 17, 2018 by kerbiloid Quote Link to comment Share on other sites More sharing options...
Nibb31 Posted April 17, 2018 Share Posted April 17, 2018 (edited) 12 minutes ago, kerbiloid said: These wings stabilizers have elevons, flaperons or so Hide contents Can they fold/extend? They fold on Cargo Dream Chaser because it launches inside a fairing. The Crew version (if it ever flies) should have fixed stabilizers, because no fairing, because of launch aborts. I don't see why it would need to retract them in flight, so it probably can't. Quote Can it fly itself from runway to runway if mislanded? Misland ? It doesn't have propulsion. If you switch runways while you're still high enough, you can glide there. Edited April 17, 2018 by Nibb31 Quote Link to comment Share on other sites More sharing options...
NSEP Posted April 17, 2018 Share Posted April 17, 2018 1 hour ago, sh1pman said: Out of the solar system? Just how much dv does that upper stage have? 10.1km/s, so it can't get out of the Solar System (i know that was a little mistake made by @sevenperforce) but it could go quite far, BFR could maybe land on the Moons of Jupiter and Saturn with the help of a few gravity assists from LEO. Not saying it will. Quote Link to comment Share on other sites More sharing options...
Ultimate Steve Posted April 17, 2018 Share Posted April 17, 2018 16 minutes ago, NSEP said: 10.1km/s, so it can't get out of the Solar System (i know that was a little mistake made by @sevenperforce) but it could go quite far, BFR could maybe land on the Moons of Jupiter and Saturn with the help of a few gravity assists from LEO. Not saying it will. If we're talking gravity assists, and if we have pinpoint accuracy with S2, it could theoretically escape the solar system, I think, given that TESS is so light and there will probably be a lot of fuel left over. Quote Link to comment Share on other sites More sharing options...
Technical Ben Posted April 17, 2018 Share Posted April 17, 2018 Elon should never play KSP then... I had a habit of sending old craft off to new planets/moons and landing there just for "fun". XD Quote Link to comment Share on other sites More sharing options...
sevenperforce Posted April 17, 2018 Share Posted April 17, 2018 (edited) 18 minutes ago, Ultimate Steve said: If we're talking gravity assists, and if we have pinpoint accuracy with S2, it could theoretically escape the solar system, I think, given that TESS is so light and there will probably be a lot of fuel left over. Falcon Heavy's upper stage can go out of the solar system without a gravity assist. 35 minutes ago, NSEP said: 10.1km/s, so it can't get out of the Solar System (i know that was a little mistake made by @sevenperforce) but it could go quite far, BFR could maybe land on the Moons of Jupiter and Saturn with the help of a few gravity assists from LEO. Not saying it will. BFS, if properly refueled in elliptical Earth orbit, could make it to gas giant destinations without gravity assists. Not coming back though. Edited April 17, 2018 by sevenperforce Quote Link to comment Share on other sites More sharing options...
Ultimate Steve Posted April 17, 2018 Share Posted April 17, 2018 1 hour ago, sevenperforce said: Falcon Heavy's upper stage can go out of the solar system without a gravity assist. BFS, if properly refueled in elliptical Earth orbit, could make it to gas giant destinations without gravity assists. Not coming back though. Yes, FH can do it, but I'm curious as to if F9 could... As for BFS, maybe aerocapture, gravity assists from moons, and landing some place you can refuel? The aerocapture would probably be too intense, though. Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted April 17, 2018 Share Posted April 17, 2018 2 minutes ago, Ultimate Steve said: The aerocapture would probably be too intense, though. Not if they have a giant party balloon... and a bouncy house... Bouncy house probably won't help with the aerocapture, but c'mon, bouncy house in space y'all! Quote Link to comment Share on other sites More sharing options...
Delay Posted April 17, 2018 Share Posted April 17, 2018 (edited) 5 minutes ago, Ultimate Steve said: Yes, FH can do it, but I'm curious as to if F9 could... I can imagine it could if the first stage is expended and the payload is very light. Edited April 17, 2018 by Delay Quote Link to comment Share on other sites More sharing options...
tater Posted April 17, 2018 Share Posted April 17, 2018 I was talking to my son about BFR on the way to school this morning, and it got me thinking about how the economics of launch works, even in the case of expendable vehicles. The ITS numbers from SpaceX were something like 200 M$ for the ITS, 230 M$ for the booster, and 130 M$ for the tanker/cargo variant. Let's assume that the current, smaller BFR/BFS costs exactly the same. Forget the crew vehicle for now. A complete stack is then 260 M$. Tha's what, 100M$ less than the retail cost of a Delta IV Heavy? Even expended, it's cheap. There is no reason not to expect the booster to fly at least the 10 times a Block 5 is supposed to, it's basically identical, but larger. So with the booster used only 10 times, a BFR would cost 156 M$! That's 1 M$/tonne ($1000/kg), even with no stage 2 reuse at all. Remember, I'm using the 12m prices here, not the 9m prices. If the spacecraft can only be reused a few times for whatever reason, it gets cheaper still. Assume just 1 reflight of the cargo stage, and 10 for the booster. The cost is now 88 M$ for 150 tons. $587,000 per tonne, or $587/kg. If both can be reused only 10 times, then we're at 26 M$ per flight. 10 too optimistic? How about 5? Still basically F9 cost for 150 tonnes to LEO. Quote Link to comment Share on other sites More sharing options...
Ultimate Steve Posted April 17, 2018 Share Posted April 17, 2018 38 minutes ago, tater said: I was talking to my son about BFR on the way to school this morning, and it got me thinking about how the economics of launch works, even in the case of expendable vehicles. The ITS numbers from SpaceX were something like 200 M$ for the ITS, 230 M$ for the booster, and 130 M$ for the tanker/cargo variant. Let's assume that the current, smaller BFR/BFS costs exactly the same. Forget the crew vehicle for now. A complete stack is then 260 M$. Tha's what, 100M$ less than the retail cost of a Delta IV Heavy? Even expended, it's cheap. There is no reason not to expect the booster to fly at least the 10 times a Block 5 is supposed to, it's basically identical, but larger. So with the booster used only 10 times, a BFR would cost 156 M$! That's 1 M$/tonne ($1000/kg), even with no stage 2 reuse at all. Remember, I'm using the 12m prices here, not the 9m prices. If the spacecraft can only be reused a few times for whatever reason, it gets cheaper still. Assume just 1 reflight of the cargo stage, and 10 for the booster. The cost is now 88 M$ for 150 tons. $587,000 per tonne, or $587/kg. If both can be reused only 10 times, then we're at 26 M$ per flight. 10 too optimistic? How about 5? Still basically F9 cost for 150 tonnes to LEO. ...And that's if they miss the lower end of their reuse goals by a factor of ten! Quote Link to comment Share on other sites More sharing options...
Nefrums Posted April 17, 2018 Share Posted April 17, 2018 The problem is finding 150t of payload that wants to be in the same orbit. That could be solved by building a small satellite kicker stage with a few km/s dV. And strap one of those to each satellite. Quote Link to comment Share on other sites More sharing options...
tater Posted April 17, 2018 Share Posted April 17, 2018 40 minutes ago, Nefrums said: The problem is finding 150t of payload that wants to be in the same orbit. That could be solved by building a small satellite kicker stage with a few km/s dV. And strap one of those to each satellite. This is true for the current market, for sure. When all you need to fly is comsats, then yeah, it makes little sense. If you wish to do anything else, however, then the vast mass to orbit matters. Things get expensive when they have to work perfectly because too much redundancy is impossible due to mass constraints. If you can fly 150t for the same price as a GEO comsat (same price via already cheap SpaceX), then you can experiment with things that you might not. Send a large asteroid miner? Inflatable station witht he idea of selling access, etc, etc. The existence of new modes of transport creates previously unknown markets. I think it's pretty transformative, even outside the usual customers. When BFR looks like it's going to be a thing (meaning it is clear it can work at some level, so after some hops), it's time to think laterally in earnest about some novel businesses in space. 88 M$ is the sort of money that is not impossible to raise for the right idea. If a plan requires an SLS launch, you better be the government, but as the price drops, a lot is possible. Quote Link to comment Share on other sites More sharing options...
sh1pman Posted April 17, 2018 Share Posted April 17, 2018 Capacity to lift 150t to orbit means you can have a normal-size probe with its own big and heavy kick stage. Opens up direct missions to outer Solar system, gas giant moons, Kuiper belt, etc. Want to terraform Mars? No problem, send a huge ion-powered tug to an icy Kuiper belt asteroid and bring it down to cross Mars orbit. Works even better if NTRs become a thing, because you can extract hydrogen from water ice and use it for propulsion. Also solves the power problem. Quote Link to comment Share on other sites More sharing options...
NSEP Posted April 17, 2018 Share Posted April 17, 2018 BFR has alot of space to play with, for a cheap price, wich is what we currently lack for litterly every space dream we have right now. This allows for a much bigger market. Quote Link to comment Share on other sites More sharing options...
tater Posted April 17, 2018 Share Posted April 17, 2018 ^^^true, only issue is it’s a new market, so we need some outside the box thinking. Quote Link to comment Share on other sites More sharing options...
Rakaydos Posted April 17, 2018 Share Posted April 17, 2018 (edited) BFR can put 150,000 1u Cubesats into orbit for $33.34 each. Mind blown. Edit: 1.33 kg per cubesat, not 1 kg. so 750 cubesats per ton, 150 tons, 112,500 cubesats for $45 each. Edited April 17, 2018 by Rakaydos Quote Link to comment Share on other sites More sharing options...
StrandedonEarth Posted April 17, 2018 Share Posted April 17, 2018 2 minutes ago, Rakaydos said: BFR can put 150,000 1u Cubesats into orbit for $33.34 each. Mind blown. Into nearly identical orbits, with the mother of all cubesat dispensers... Quote Link to comment Share on other sites More sharing options...
Rakaydos Posted April 17, 2018 Share Posted April 17, 2018 2 minutes ago, StrandedonEarth said: Into nearly identical orbits, with the mother of all cubesat dispensers... That matters a lot less for school projects. Quote Link to comment Share on other sites More sharing options...
CatastrophicFailure Posted April 17, 2018 Share Posted April 17, 2018 26 minutes ago, Rakaydos said: That matters a lot less for school projects. Yeah, but... 150k cubesats with no propulsion all in the same orbit... I’m reminded of that one scene from WALL-E. That, or the start of earth’s very own Halo ring... Quote Link to comment Share on other sites More sharing options...
tater Posted April 18, 2018 Share Posted April 18, 2018 Cubesats are a thing because every gram matters. When payloads are not mass or even much volume limited, then different design constraints apply. Just make sats with loads of propellants for electric propulsion. Quote Link to comment Share on other sites More sharing options...
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