I'm delighted to see that Dream Chaser is making progress; at least there's a spaceplane successor to the Shuttles as well as the new capsules.I do have a few minor reservations about Dream Chaser's skid strip nose gear though; how does a pilot steer Dream Chaser after touchdown, for example to compensate for a crosswind or a flat tyre on the main gear?I'm not sure what material the skid strip would be made from, but wouldn't a solid piece of whatever material is used suffer too much friction scraping against the runway and possibly be damaged? Will the skid strip be replaced after every landing like the Shuttle Orbiter's tyres or not?Also, how would Dream Chaser be moved to the hangar/OPF after landing; would it be towed like the Shuttle Orbiter, but with the skid strip scraping on the ground, towed on its main gear only with the skid strip raised off the ground somehow, or loaded onto a wheeled transporter similar to the one used to roll the Shuttle Orbiters over to the VAB for stacking?
The skid does about the same for a pilot as any nosewheel in the initial portion of the landing of a high performance aircraft- i.e. stay straight and don't shimmy. That is all you want it to do- period. So far a a cross wind, the best way to handle it is to simply avoid it as much as you can. in other words do not crab well (see Milt Thompson's "Flying Without Wings" and Dale Reed's "Wingless Flight"). Thus, in short, you select landing times and sites where the crosswind is a very low factor. So far as a "blown tire" you do what any pilot would do- hope not. No matter if you had a skid or a nosewheel, in the case of a blown main, it would make very little differance in the outcome IMO. In fact the skid would likely have greater surface to runway friction and thus would likely help slghtly more as far as stability in the landing roll is concerned. Things that normally blow tires are almost nonexistant in the environment that a spacecraft would be operational in, however (FOD heavy wear from repeated cycles -(because new tires are cheap) and so on).
Quote from: Disco747 on 07/12/2012 07:03 pmI'm delighted to see that Dream Chaser is making progress; at least there's a spaceplane successor to the Shuttles as well as the new capsules.I do have a few minor reservations about Dream Chaser's skid strip nose gear though; how does a pilot steer Dream Chaser after touchdown, for example to compensate for a crosswind or a flat tyre on the main gear?I'm not sure what material the skid strip would be made from, but wouldn't a solid piece of whatever material is used suffer too much friction scraping against the runway and possibly be damaged? Will the skid strip be replaced after every landing like the Shuttle Orbiter's tyres or not?Also, how would Dream Chaser be moved to the hangar/OPF after landing; would it be towed like the Shuttle Orbiter, but with the skid strip scraping on the ground, towed on its main gear only with the skid strip raised off the ground somehow, or loaded onto a wheeled transporter similar to the one used to roll the Shuttle Orbiters over to the VAB for stacking? Differential braking and a nose gear dolly...
Quote from: Rocket Science on 07/13/2012 10:49 pmMounts soapbox…Well we’re hearing talk of Dream Chaser might not make the cut. So why do they offer the service to ESA?Not sure you phrased that second sentence the way you meant to do.Quote DC is launch vehicle agnostic so why not Ariane V or Soyuz. This bird deserves to fly, if the powers that be in the U.S. don’t appreciate it then offer it up internationally. She has waited 20 plus years from her first iteration, long enough I think…ITAR.
Mounts soapbox…Well we’re hearing talk of Dream Chaser might not make the cut. So why do they offer the service to ESA?
DC is launch vehicle agnostic so why not Ariane V or Soyuz. This bird deserves to fly, if the powers that be in the U.S. don’t appreciate it then offer it up internationally. She has waited 20 plus years from her first iteration, long enough I think…
Mounts soapbox…Well we’re hearing talk of Dream Chaser might not make the cut. So why don't they offer the service/vehicle to ESA?
Quote from: Rocket Science on 07/13/2012 10:49 pmMounts soapbox…Well we’re hearing talk of Dream Chaser might not make the cut. So why don't they offer the service/vehicle to ESA? We are? goes to double check L2
Quote from: zerm on 07/12/2012 11:32 pmThe skid does about the same for a pilot as any nosewheel in the initial portion of the landing of a high performance aircraft- i.e. stay straight and don't shimmy. That is all you want it to do- period. So far a a cross wind, the best way to handle it is to simply avoid it as much as you can. in other words do not crab well (see Milt Thompson's "Flying Without Wings" and Dale Reed's "Wingless Flight"). Thus, in short, you select landing times and sites where the crosswind is a very low factor. So far as a "blown tire" you do what any pilot would do- hope not. No matter if you had a skid or a nosewheel, in the case of a blown main, it would make very little differance in the outcome IMO. In fact the skid would likely have greater surface to runway friction and thus would likely help slghtly more as far as stability in the landing roll is concerned. Things that normally blow tires are almost nonexistant in the environment that a spacecraft would be operational in, however (FOD heavy wear from repeated cycles -(because new tires are cheap) and so on).Was this part of the reasoning why they went for a skid in that position rather than a wheel, or is there more to it than that?
Quote from: Rocket Science on 07/13/2012 11:32 pmQuote from: Jorge on 07/13/2012 11:26 pmQuote from: Rocket Science on 07/13/2012 10:49 pmMounts soapbox…Well we’re hearing talk of Dream Chaser might not make the cut. So why do they offer the service to ESA?Not sure you phrased that second sentence the way you meant to do.Quote DC is launch vehicle agnostic so why not Ariane V or Soyuz. This bird deserves to fly, if the powers that be in the U.S. don’t appreciate it then offer it up internationally. She has waited 20 plus years from her first iteration, long enough I think…ITAR.Hey Jorge,What I'm thinking is along the lines that we had with the X-38/CRV and ESA if it had come to be. If that was flying today how would ITAR affect it?~Robert(Thanks Jorge fixed that, little frustrated I guess...)http://www.spaceref.com/news/viewnews.html?id=353http://www.esa.int/esaHS/ESARZS0VMOC_iss_0.htmlhttp://www.theconquestofspace.com/2011/03/saga-of-x-38.htmlA couple of things I observed as ITAR was implemented at NASA:1) Although the relevant laws were passed in the late 1990s, the law required the State Department to write a bunch of regulations to actually implement it. This "trickled down" to NASA over the following decade. The effects this would have had on any plans to fly X-38/CRV on Ariane did not become evident prior to X-38 cancellation.2) The law treats transfers by private companies markedly differently than transfers by the US government itself.#2 manifested itself in the ISS program in some pretty perverse ways, such as contractor employees not being allowed to make certain presentations when ISS international partners were in the room, but if the presentation were handed to a NASA civil servant and he presented it, that was no problem. And that was indeed the short-term workaround, followed by a mid-term workaround of actually rebadging some contractors as civil servants, and a long-term solution of NASA obtaining a "generic" export license allowing contractors to interact with ISS IPs.(The very fact that NASA was willing to consider hiring away contractor personnel as the *mid* term solution should be a clue as to just how much of a pain in the ass it was for NASA to get that generic license.)So my take on it is that flying X-38 on Ariane, had it survived, would have had to deal with a period of awkward transition to deal with ITAR, much like the ISS program did. And second, that Sierra Nevada would have a considerably tougher time getting the required export licenses than the ISS program did. They would need to do their own cost-benefit analysis to determine if it's worthwhile for them.
Quote from: Jorge on 07/13/2012 11:26 pmQuote from: Rocket Science on 07/13/2012 10:49 pmMounts soapbox…Well we’re hearing talk of Dream Chaser might not make the cut. So why do they offer the service to ESA?Not sure you phrased that second sentence the way you meant to do.Quote DC is launch vehicle agnostic so why not Ariane V or Soyuz. This bird deserves to fly, if the powers that be in the U.S. don’t appreciate it then offer it up internationally. She has waited 20 plus years from her first iteration, long enough I think…ITAR.Hey Jorge,What I'm thinking is along the lines that we had with the X-38/CRV and ESA if it had come to be. If that was flying today how would ITAR affect it?~Robert(Thanks Jorge fixed that, little frustrated I guess...)http://www.spaceref.com/news/viewnews.html?id=353http://www.esa.int/esaHS/ESARZS0VMOC_iss_0.htmlhttp://www.theconquestofspace.com/2011/03/saga-of-x-38.html
Thank you Jorge for the very insightful answers. I can appreciate the need for arms controls especially what has happened in the past, but the very fact that we export fighter planes and other weapons systems to our allies even today is interesting (many of them are ISS partners). Also as you know ILS also flys U.S. spacecraft on foreign launchers as well on a regular basis. If thing do go badly for SNC in this competition at least they may have an option with this route. I know ESA got burned with the X-38/CRV project and may be a bit gun shy to repeat it again. Perhaps JAXA might be interested as well on their launchers. So it might be challenging for this to happen, but not impossible for the ISS partners to have greater autonomy as they have wished for in the past with their own vehicle.
Quote from: Rocket Science on 07/14/2012 10:17 amThank you Jorge for the very insightful answers. I can appreciate the need for arms controls especially what has happened in the past, but the very fact that we export fighter planes and other weapons systems to our allies even today is interesting (many of them are ISS partners). Also as you know ILS also flys U.S. spacecraft on foreign launchers as well on a regular basis. If thing do go badly for SNC in this competition at least they may have an option with this route. I know ESA got burned with the X-38/CRV project and may be a bit gun shy to repeat it again. Perhaps JAXA might be interested as well on their launchers. So it might be challenging for this to happen, but not impossible for the ISS partners to have greater autonomy as they have wished for in the past with their own vehicle.Not true. Fighters are not launch vehicles and aren't controlled the same way. Same goes for integrating spacecraft onto launch vehicles, not the same thing as giving them the hardware.No, SNC doesn't really have the options as you describe.They only can sell rides and not the vehicle
Quote from: Star One on 07/13/2012 06:57 pmQuote from: zerm on 07/12/2012 11:32 pmThe skid does about the same for a pilot as any nosewheel in the initial portion of the landing of a high performance aircraft- i.e. stay straight and don't shimmy. That is all you want it to do- period. So far a a cross wind, the best way to handle it is to simply avoid it as much as you can. in other words do not crab well (see Milt Thompson's "Flying Without Wings" and Dale Reed's "Wingless Flight"). Thus, in short, you select landing times and sites where the crosswind is a very low factor. So far as a "blown tire" you do what any pilot would do- hope not. No matter if you had a skid or a nosewheel, in the case of a blown main, it would make very little differance in the outcome IMO. In fact the skid would likely have greater surface to runway friction and thus would likely help slghtly more as far as stability in the landing roll is concerned. Things that normally blow tires are almost nonexistant in the environment that a spacecraft would be operational in, however (FOD heavy wear from repeated cycles -(because new tires are cheap) and so on).Was this part of the reasoning why they went for a skid in that position rather than a wheel, or is there more to it than that?Could not say what their reasoning is- all I'm saying is that under the circumstances in question, the skid is just as effictive.Also; Keep in mind that most "blown tires" that I've seen (as both a pilot and a mechanic) were caused by FOD picked up on the takeoff roll and not the landing roll. The exceptions being emergency landings, locked brakes, anti-skid malfunctions combined with unusually heavy braking and so on. Tires used on vehicles such as DC are not what most people would consider to be "tires" such as those you use on your car or even on an airliner. I'm sure they will be engineered to easily be able to take the stress on the very few landings that each will be subjected to. The skid will be just fine IMO.
Quote from: Jim on 07/14/2012 12:27 pmQuote from: Rocket Science on 07/14/2012 10:17 amThank you Jorge for the very insightful answers. I can appreciate the need for arms controls especially what has happened in the past, but the very fact that we export fighter planes and other weapons systems to our allies even today is interesting (many of them are ISS partners). Also as you know ILS also flys U.S. spacecraft on foreign launchers as well on a regular basis. If thing do go badly for SNC in this competition at least they may have an option with this route. I know ESA got burned with the X-38/CRV project and may be a bit gun shy to repeat it again. Perhaps JAXA might be interested as well on their launchers. So it might be challenging for this to happen, but not impossible for the ISS partners to have greater autonomy as they have wished for in the past with their own vehicle.Not true. Fighters are not launch vehicles and aren't controlled the same way. Same goes for integrating spacecraft onto launch vehicles, not the same thing as giving them the hardware.No, SNC doesn't really have the options as you describe.They only can sell rides and not the vehicleFair enough Jim. They still are sensitive technologies. I guess we'll have to see it play out...RegardsRobert
