Gemini: We can rebuild it, we have the technology

[scottb50]

Maybe it is because he realizes the only way to do Commercial Space is with enough re-usability to make it economically possible. If it costs $2,000 a pound to reach orbit it would cost $400,000 just to get to a Bigelow Orbiting Hotel, assuming as normal human and baggage for a few days stay. Through in the staff and provisions to accomodate that person and the cost soars.<br /><br />If all you have to do is re-fuel and re-launch the cost would drop dramatically. <div class="Discussion_UserSignature"> </div>

 

[gunsandrockets]

What is so strange is how the written requirements differ so much from the numerous press releases and stories about the prize. The stories all emphasized that any launch vehicle would do, that the point was development of a manned orbital spacecraft. Very odd.<br /><br />The way the requirement is written is odd too, "No more than twenty percent (20%) of the Spacecraft may be composed of expendable hardware." 20% of what? Mass? And what is the definition of hardware? Does solid propellent fall into the category?

 

[mrmorris]

<font color="yellow">"The requirements apply only to the manned orbital space vehicle and not the launch vehicle. You can't water down the orbital vehicle reuse requirements by lumping it in with the launch vehicle's mass."<br /><br />"And it's a good thing too since no launch vehicle, including the SpaceX vehicles would qualify under the ASP requirements."</font><br /><br />As has already been pointed out -- you're incorrect. And as you have already given me crud for presuming to state that you might not have read the thread, doubtless I need not remind you that I've already run some calculations using estimates of Falcon-V's reusable mass. It has the <b>potential</b> of meeting the mass requirements. Since none of this exists -- the best you can say of *anything* is that there is the possibility of success.<br /><br /><font color="yellow">"And it's a good thing too since no launch vehicle, including the SpaceX vehicles would qualify under the ASP requirements. SpaceX has received government money for it's launch vehicle development."</font><br /><br />Here we get into splitting hairs and determining exactly what Bigelow means by his wording. Doubtless SpaceX or any competitor will get clarifications on exactly what is meant by: <i>"The Competitor must not accept or utilize Government development funding related to this Contest of any kind, nor shall there be any Government development funding related to this Contest of any kind, nor shall there be any Government ownership of the Competitor."</i>. The Falcon-V has been in development since long before the ASP existed, and it is *not* specifically something developed 'for this contest'. By contrast, a capsule developed to be placed on top of the Falcon-V obviously would be. I would expect that Bigelow would discount the launcher in this instance -- but it's definitely something that a competitor would want in writing before spending money developing the craft.<br /><br /><font color="yellow">"And eve</font>

 

[gunsandrockets]

Rather than argue about how many angels can dance on the head of a pin, I intend to get to the bottom of the ASP rules. I tried calling today (Sunday), no answer -- that's no surprise. I will try again Monday.

 

[gunsandrockets]

" the turnaround time for a reusable craft is very unlikely to be linear with size. There's more likely to be a steep curve upward in turnaround time as the mass (and therefore complexity) increases. "<br /><br />Size is not the answer. Otherwise why does a 747 jetliner with an empty weight of 159 tonnes have a turnaround time of an hour compared to the turnaround time of a shuttle orbiter with an empty weight of 99 tonnes?

 

[najab]

><i>How fast do the orbiters normally get turned around? What's the fastest they have ever been turned around?</i><p>Offhand I would guess that the fastest would have been OV-102 between missions STS-83 and STS-94. This was a particularly short turnaround since it was a reflight of the same mission (the first flight was cut short by a fuel cell problem).<p>The vehicle arrived at the pad on March 11 for the first launch, and was back on the pad on June 11 for the second launch. So that's 3 months for the turnaround.<p>Normally, it's more like 4-5 months.</p></p></p>

 

[mrmorris]

<font color="yellow">" This was a particularly short turnaround since it was a reflight of the same mission "</font><br /><br />Which is another way of saying that much of the 'turnaround time' of the orbiters is actually spent reconfiguring the payload bay for a new mission. This, of course, has no equivalent for G-X3. So the orbiter can be turned around in ~90 days without having to rebuild the payload bay... but turning around a fixed-purpose capsule less than 8% of that size in 60 days is considered to be somewhere between difficult and impossible? <br /><br />I don't think so.

 

[najab]

><i>So the orbiter can be turned around in ~90 days without having to rebuild the payload bay...</i><p>Remember that the 90 days included replacing a fuel cell, which isn't a simple task due to their location.</p>

 

[mrmorris]

I <b>really</b> like t/Space's seating idea for their CXV. The fabric 'slings' they came up with are 10% of the mass of the seats in the shuttle orbiters, and have several other nifty features as well. When not in use, they could be unhooked and stored out of the way. This would allow the craft to be easily used for carrying <5 people plus some cargo, and would also simply refurb operations. It will be much easier for ground crew to check out the systems of the craft between flights with the entire crew cabin opened up.

 

[ve7rkt]

Michael Schumacher does not lie in a hammock when he's pulling 4G's in his Ferarri... I can't bring myself to imagine that a space capsule pilot should. I would want something a little more secure. The difference, I guess, is that Schumi pulls 4G in rapidly changing directions, while the capsule's crew's g-forces will all be to the aft, but still...

 

[gunsandrockets]

"Michael Schumacher does not lie in a hammock when he's pulling 4G's in his Ferarri... I can't bring myself to imagine that a space capsule pilot should. I would want something a little more secure. The difference, I guess, is that Schumi pulls 4G in rapidly changing directions, while the capsule's crew's g-forces will all be to the aft, but still... "<br /><br />Imagine the fun in the t/Space capsule when the "hammock" flips 180% under the power of the torsion bar springs the seats are connected to. I wonder how many oscillations the seat will undergo before settling down? Not terribly dignified, but if it works, what the hell.

 

[nacnud]

I've spent many weekends sitting/lying in hammocks that are probably 10% the mass of the ones proposed by t/space. <br /><br />Sailors often use trapezes to help keep dinghies upright, a classic example is the 18 foot skiff. While the cheep harnesses are often uncomfortable spend a bit more money and get one with a spreader bar and decent adjustments and you can spend 3 hours plus dangling from a wire in complete comfort.<br /><br />Don't underestimate the power of textile technology.<br />

 

[geoffc]

Having done trapeze while sailing (admitadly on a 14 foot Laser II, 2 man boat) I can say, that is quite a comfortable position to be in. But of course, it is only good in a nice predictable gravity field...

 

[nacnud]

I used to sail Laser II and ISOs as well <img src="/images/icons/smile.gif" />

 

[mrmorris]

Found a couple more interesting documents about the Low Power Transceiver (LPT). The older of the two is a fairly technical description about how it was constructed and was written in 2001 -- about the time they'd built the second-generation of the LPT. The second document is a Powerpoint Presentation -- less technical details, but written in mid-2003 after they'd completed the third-generation LPT. What's interesting in both is that they make reference to a fourth generation which is going to take a major step beyond -- enough that it's being renamed.<br /><br />The current LPT has a volume of about 100 cubic inches -- a cube approximately 5" on a side. They're designing the next generation (the Mini Transceiver or MinT) to be a cube only 2" on a side for a total volume of <b>8 cubic inches</b>! They mention this would allow the capability to build the transceiver <b>inside the antenna structure itself</b> to eliminate cable transmission losses.<br /><br />What made me think of this was an article yesterday on SpaceDaily about Actel announcing an advancement in its FPGA packaging: <i>"Actel, a provider of programmable logic solutions, announced last Tuesday a new packaging option for its field-programmable gate array (FPGA) devices that is designed to significantly reduce board size and weight in space-constrained, military/aerospace applications."</i> The LPT is largely composed of FPGAs, and this announcement by Actel has the potential of pushing the MinT from 'someday' to 'soon'. ITT went from the first generation to the third between 1999 and 2003. The MinT may very well be available in the next year or two, which would give G-X3 an amazingly small and light communications system.

 

[ve7rkt]

Man, when they talk "low power," they're not kidding. My handheld ham rig is around the same volume as the LPT, including battery, and it puts out 1W or 3.5W of head-microwaving fun. If I read the docs here right, they're talking about 115mW. But then, my handheld doesn't handle data encoding, DSP for consumer electronics didn't exist yet when it was built, and it CERTAINLY can't listen to 32 separate receiver channels while broadcating on four separate transmit channels! <img src="/images/icons/smile.gif" /><br /><br />The Alinco DJ-C5T handheld radio is 3.42 cubic inches, 3oz, and in addition to pumping out 300mW on two different bands, it has a mosquito repeller. Three of these, special ordered to cover whatever radio band we need instead of the 2m/70cm ham bands, would be smaller than the current LPT and handle our needs, though it would have fewer features -- the onboard computer would be responsible for all the data encrypting and encoding.<br /><br />I've only skimmed the document, but it seems to me that the LPT or MiniT would have to be special ordered for the GX3 anyhow, unless we want it to use TDRSS.<br /><br />I volunteer to set up Ground Station Vancouver, if Mr. Bigelow will buy me some land on a suburban mountaintop.

 

[mrmorris]

<font color="yellow">"...unless we want it to use TDRSS."</font><br /><br />Um -- TDRSS was sort of the point. It gives uninterrupted communications throughout the orbit. The comm functions of G-X3 aren't really something we want to skimp on. We need voice and telemetry 110% of the time. Data encoding is also pretty important, as we don't really want to have to rely on the cooperation of HAM operators around the world to stay off the freq in use so that G-X3 can communicate with ground control without interruption.

 

[ve7rkt]

Absolutely... which is why I said, if we had Alnico or some similar company build our radio gear, it'd be built for bands other than the amateur band, where encryption would be permitted and interference less common. I'm just using amateur gear as a guideline for mass & power consumption. We have a guy in Vancouver who not only interferes with the local repeaters in the most interesting ways, but screws around with the emergency bands too. I heard there was a guy in Victoria messing around with the Victoria airport ILS a few years back! For mission-critical stuff, you definitely don't want to be playing with public bands.<br /><br />But I didn't think we'd be permitted to use TDRSS, I figured we might have to build our own private TDRSS-style satellites using a separate radio band. If you think we will be able to rent time on TDRSS, though, I'll shut up. <img src="/images/icons/smile.gif" /><br /><br />Since I don't know what I can do to help GX3, I'll rough out specs for a relay satellite. I'll keep it off this list, though, I know this is to be kept to the topic of GX3 only.

 

[mrmorris]

<font color="yellow">"I'm just using amateur gear as a guideline for mass & power consumption."</font><br /><br />Keep in mind the LPT is rad-hardened. That probably precludes Alnico from building it *and* likely contributes to increased power consumption.<br /><br /><font color="yellow">"But I didn't think we'd be permitted to use TDRSS,"</font><br /><br />I don't know it for <b>positive</b>. However, where I found the LPT was when NASA loaned it to Rutan for use on the GlobalFlyer. Also, I've seen articles talking about how expensive it is to use -- which would indicate that NASA sells time on it (I'm not *hugely* concerned about the expense, as these would have been unmanned satellites that used it continuously over a period of years rather than intermittantly for 1-2 days as would a manned 'taxi'). As I mentioned to najaB when he brought this question up earlier -- if a craft like G-X3 is built and NASA *doesn't* allow it to use the TDRSS, then they'll be crucified by Congress.

 

[mrmorris]

I'm trying to work out an approximation of the heating load that G-X3 will experience to get an idea of the magnitude of the thermal control system required. As usual -- I'm flying on a wing and a prayer, as this is **definitely** not my area of expertise. I'm using the document here as the basis for the formulas and several heaint load values for calculating this. Unfortunately -- I don't think they're 100% complete. In particular -- they don't take into account the Solar absorptance of the spacecraft coating when calculating the heating from the sun and the Earth's albedo. There may well be other issues, but this is certainly the most comprehensive doc I've found so far. If anyone can provide more details, corrections, additional reference docs, etc. -- I'd be glad to see them.<br /><br />Heating from Solar radiance: ~1353 W/m2<br />Heating from Earth's albedo: ~405 W/m2<br />Approx 'planar' surface area of G-X3 for raditative heating calcs: ~8m2<br /><br />Qsun then is: 10824W<br />Qearth is: 3240W<br /><br />Approximation of heat generated by crewmembers:<br /><br /> Eb = 5.67x10^-8 W/m2 K^4 * 310K ^4<br /> Eb = 5.67x10^-8 W/m2 K^4 * 9235210000 K^4<br /> Eb = 523 W/m2<br /><br />We'll assume each crewmember has 1 square meter of surface area <img src="/images/icons/smile.gif" /> )<br /><br />Qcrew = (523W * 1m2 * 5)<br />Qcrew = 2615 W<br /><br />The equipment will generate approximately as much heat as the power used. Power usage on G-X3 currently sits at a nominal rate of ~150 watts. It's likely more equipment will be added, so I'll assume 200W as a final power usage.<br /><br />Qequipment = 200W<br /><br />The heat to be dissipated then is approximately:<br /><br />Qdiss = Qsun*Sa + Qearth*Sa + Qequipment + Qcrew<br />Qdiss = 10824W*.2 + 3240W*.2 + 200W + 2615W<br />Qdiss = 2615W + 648W + 200W + 2615W<br />Qdiss = 6078W<br /><br />Sa = Solar absorptance. I'm using white paint, which has a Solar

 

[najab]

><i>However, this would tend to imply that G-X3 requires only a very small degree of active thermal control to keep the cabin temperature comfortable for the crew.</i><p>From a purely intuative approach, this doesn't sound unreasonable. Especially when you consider that the capsule will be cold soaked for half of each orbit. A couple of heat-pipes connected to some external plates with high thermal inertia might be all it needs.</p>

 

[mrmorris]

<font color="yellow">"From a purely intuative approach, this doesn't sound unreasonable."</font><br /><br />Well I was thinking about it from the standpoint of Gemini and Apollo -- both of which had fairly substantial cooling systems onboard. However, I guess if I modify the figures for Apollo -- increasing the average solar flux (multiply by 1.9 because it's no longer in shadow for a bit under half of its orbit), changing to three crewmembers, setting nominal power usage to 1kW of power, and eliminating the flux from Earth's albedo, I get:<br /><br />Qdiss = Qsun*Sa + Qequipment + Qcrew <br />Qdiss = 20565W*.2 + 1000W + 1569W <br />Qdiss = 4113W + 1000W + 1569W <br />Qdiss = 6682W <br /><br />T = (Qdiss / Aes )^1/4 <br />T = (6682W / 16m2 * .9 * 5.67x10^-8 W/m2 K^4) ^1/4 <br />T = (6682W / 0.00000081648)^ 1/4 <br />T = (8183911424^4)^1/4 <br />T = 300K ( 80 degrees F) <br /><br />OK -- so the increase in increase in average solar flux would have meant Apollo required a more substantial cooling system. Makes sense -- adds a bit more credibility to my voodoo math. <img src="/images/icons/smile.gif" />

 

[rancamp]

Me:<br /> />So I'm curious as to what 'special' factors you consider<br /> />a 'capsule' parachute to require?<br /><br />gunsandrockets:<br /> />It's a simple question of costs vs. benefits. Re-using<br /> />the parachutes would be a foolish economy.<br /><br />Ahh, in other words "none" the actual question. And your correct, there ARE no special requirements!<br />Thanks for admiting it. Now as to the 'economy' problems you mention...<br /><br />We'll take them one at a time, sort of...<br /><br /> />Sure it's possible to re-use the parachutes,<br /><br />Sure it is, and done routinely on a daily basis worldwide with much higher mass' too. Cheap, easy, off the shelf technology and practices.<br /><br /> />...but would you really want to do so?<br /><br />Sure it's done all the time. It's a heck of a lot cheaper than throwing them away after every use. (Not that doing THAT is all that expensive either <img src="/images/icons/blush.gif" />)<br /><br /> />How carefully should the chutes be inspected before<br /> />re-use? How does that inspection meld with the<br /> />necessity of a 60 day turn-around time? How many<br /> />times could the chutes be reused? What is the margin<br /> />of safety?<br /><br />This, of course is why this forum exists, so that those who have questions can get answers. Since you seem to have never dealt with air cargo delivery systems, I'll fill you in. There are both military and civil systems for airdropping cargo. Both have fairly rigid inspection, care, and re-packing criteria. At MOST a complete inspection, washing, drying, rigging, and re-pack takes a week. That's with around two people working on all three chutes.<br />Chutes should be good for at least a dozen uses as long as inspections and repairs are kept up.<br />And IIRCC the allowed 'failure' rate for cargo chutes is less than 10% while manned chutes are less than 1%.<br />See? It helps when you know something on the subject your talking about.<br /><br /> />And how much mass (not much) and money<</safety_wrapper>

 

[gunsandrockets]

"There are both military and civil systems for airdropping cargo. Both have fairly rigid inspection, care, and re-packing criteria. At MOST a complete inspection, washing, drying, rigging, and re-pack takes a week. That's with around two people working on all three chutes. Chutes should be good for at least a dozen uses as long as inspections and repairs are kept up. And IIRCC the allowed 'failure' rate for cargo chutes is less than 10% while manned chutes are less than 1%."<br /><br />Ahem. You are not helping the case for reusable chutes.<br /><br />Somehow I don't think the crew of the space capsule would feel too comfortable knowing their reusable chutes would have a failure rate of 10%! Even the smaller manned chutes with a failure rate of 1% is backed up with a reserve chute. A space capsule does not have a reserve chute (though an Apollo style 3-chute system may have reserve capacity such that one of the three chutes could fail and the capsule still survive).<br /> <br /><br /> />And how much mass (not much) and money <br /> />(questionable) is really saved by reusing the chutes? <br /><br />"Hmmm, compare that mass of the chutes, (even spares) and your still well below the required mass for wings and such. Money? Flight testing and certification cost an awful lot of money. So the question more likely is, what system would cheaper than a parachute for a couple of thousand dollers each? "<br /><br />Non sequitur. The question was the cost of reusing a parachute vs packing a brand new chute for each capsule recovery. The question was not parachutes vs wings or another recovery system.<br /><br /> />And the consequences if the chutes fail? Five people <br /> />die. <br /><br />"And? Hmm, if your reentry protection fails, 5 people die, if your launch escape system fails (or you don't have one) and your booster fails, 5 people die. What's the difference? One thing to keep in mind is that there is spare mass to pack a reserve if your that worried. But really your pickin

 

[najab]

I posted that link about 400 posts ago. <img src="/images/icons/laugh.gif" />