|
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Darpa Revives Larger Reusable Booster Spaceplane
"The U.S. Defense Advanced Research Projects Agency (Darpa) plans to
seek industry interest next month in an Experimental Spaceplane (XS-1) which will be capable of delivering a payload up to 5,000 lb. to space for less than $5 million per launch. The XS-1 is targeted at flying at Mach 10 plus and generating a sortie rate of up to 10 times over 10 days. The program compliments the agency’s ongoing Airborne Launch Assist Space Access (Alasa) program, which is developing an air launch system for small satellites, and appears to be a partial revival of the Air Force Research Laboratory’s abandoned Reusable Booster System (RBS) Pathfinder. Like RBS, the XS-1 would be based on a hypersonic first stage which would deliver payloads to low Earth orbit via one or more expendable stages. The first stage would return autonomously to the launch site for reuse. Darpa, which is expected to issue a Broad Agency Announcement for XS-1 shortly, says “modular components, durable thermal protection systems and automatic launch, flight, and recovery systems should significantly reduce logistical needs, enabling rapid turnaround between flights.” See: http://www.aviationweek.com/Article...._p0-618115.xml |
#2
|
|||
|
|||
Darpa Revives Larger Reusable Booster Spaceplane
On Saturday, September 21, 2013 8:41:49 AM UTC+12, wrote:
"The U.S. Defense Advanced Research Projects Agency (Darpa) plans to seek industry interest next month in an Experimental Spaceplane (XS-1) which will be capable of delivering a payload up to 5,000 lb. to space for less than $5 million per launch. The XS-1 is targeted at flying at Mach 10 plus and generating a sortie rate of up to 10 times over 10 days. The program compliments the agency’s ongoing Airborne Launch Assist Space Access (Alasa) program, which is developing an air launch system for small satellites, and appears to be a partial revival of the Air Force Research Laboratory’s abandoned Reusable Booster System (RBS) Pathfinder. Like RBS, the XS-1 would be based on a hypersonic first stage which would deliver payloads to low Earth orbit via one or more expendable stages. The first stage would return autonomously to the launch site for reuse. Darpa, which is expected to issue a Broad Agency Announcement for XS-1 shortly, says “modular components, durable thermal protection systems and automatic launch, flight, and recovery systems should significantly reduce logistical needs, enabling rapid turnaround between flights.” See: http://www.aviationweek.com/Article...._p0-618115.xml Consider a capsule that is a frustrum 2.5 ft hatch 9.8 ft base 8.1 ft height Within this volume is carried 5,000 lbs of payload. The base of the cone consists of a zero height aerospike nozzle with MEMS based rocket array at the rim. The plug doubles as a heat sheild. There is a 2.5 ft diameter by 45.0 ft tall cylinder with a spherical nose cone. There are six tanks that when assembled around the hatch tank form a cone 45.0 ft tall and 9.0 ft in diameter. The cone, along with the hatch tank and six segment tanks each mass 1,000 lbs. Each tank carries 12,187 lbs of propellant. 1,875 lbs of hydrogen 10,312 lbs of oxygen. All tanks feed the central aerospike engine. During loading the six segment tanks can be raised 8.0 feet above the base of the cone by a pneumatic cylinder built into the hatch tank. This aids in loading and unloading the cone. A single point of loading all tanks for each propellant exists near the base of the cone. At lift off the narrow biconical shape blasts off with propellant being drained from four of the seven tanks. When empty they are dropped, slow to sub-sonic speed and fly back to the launch center for landing using air breathing engines. Meanwhile the cone with three tanks remaining continues skyward. This time two of the segment tanks are being drained to feed the aerospike engine. When drained these too are dropped, and re-enter. They slow to subsonic speed and deploy an inflatable wing along with air breathing MEMS jets, running on excess hydrogen in the propellant tank. This system too flies back to the launch center for recovery. Meanwhile the cone with a single hatch tank remains and continues skyward. This time the hatch tank is feeding the capsule, which supplies the capsule nearly all the way to orbit. The hatch tank is ejected and drops back to Earth near the launch center, deploys an inflatable wing after slowing to subsonic speed, and lands at the launch center. Meanwhile, the cone circularizes its orbit, and carries out its mission before returning to Earth and recovery at the launch center by parachute. |
#3
|
|||
|
|||
Darpa Revives Larger Reusable Booster Spaceplane
|
#4
|
|||
|
|||
Darpa Revives Larger Reusable Booster Spaceplane
|
#6
|
|||
|
|||
Darpa Revives Larger Reusable Booster Spaceplane
On 9/22/2013 8:12 AM, Robert Clark wrote:
"David Spain" wrote in message ... ... The $5 million figure is also interesting. Why that figure DARPA? I remember reading SpaceX's goal was $10 million / launch. Which is already an order of magnitude below where we are today. Wassup DARPA? $10M not good enough for ya? Dave Do you have a reference for that $10 million number? Elon in a Spacenews article said he expects to reduce costs by only 25% by a reusable first stage only: http://www.spacenews.com/article/lau...on-9%E2%80%99s No. When I double checked I saw that I was confusing the launch cost figures for non-reusable Falcon 1 and Falcon 9. Sorry. http://en.wikipedia.org/wiki/Falcon_...uture_concepts But I agree with your comments in the comment section of your cited reference however that a savings of only 25% using a fully-reusable first stage seems very conservative. Given that Musk already states that fuel is only ~0.4% of his firm's launch costs. That figure (0.3% to 0.4%) is quoted in several places but here is one reference (see para 6): http://www.popularmechanics.com/scie...-plans-6653023 And in this article we have Musk reported to be saying that the first stage accounts for 3/4 of the total price tag: http://www.space.com/21386-spacex-re...kets-cost.html So if we go at $56M for a Falcon 9, 3/4 is $42 million. Assuming no re-usability of the upper stage but a fully reusable first stage then we have a recurring cost (less fuels/ops/etc) of 56-42=$14M. From this cite: http://www.zmescience.com/space/spac...eaper-0432423/ I get a rough figure of ~$200,000 for fuel/oxidizer in the first stage so now an estimated figure ought to be in the range of $14.2 million assuming a throw-away upper stage. Still a lot better than 25%. In fact, as you point out Robert in your commentary in your cited link, 25% of the current price would seem to BE the resulting cost figure not a reduction thereof. This cost is for the rocket alone, not counting payload. Also ignoring infrastructure/operations/overhead/refurbishment costs and any amortization of the cost to build a reusable first stage. So this is I think still an optimistic figure you might see only later as the program matures and also assuming no advancement in reusable upper stage technology which ought to drive costs even lower. This is or at least ought to be achievable in the near term (within 10 years) using hardware (Grasshopper) that is undergoing test now. So I tend to believe this is where we are today at slightly beyond current state of the art. DARPA is certainly free to fund research to push beyond what is currently beyond the edge. But I find it curious no money is going to the current leader in reusable to-orbit technology. Which makes me think this is more of a "competitive technology" effort so that the government is not beholding to one-vendor. Not necessarily a bad thing either. IF those competitors can deliver. Or maybe SpaceX is just coming late to the game and will participate in the program with a Dragon atop a "Falcon 9R+", with the DARPA money to be used to develop a fully reusable upper stage. We'll see... Dave |
#7
|
|||
|
|||
Darpa Revives Larger Reusable Booster Spaceplane
On 9/22/2013 7:14 AM, me wrote:
Suggest you go look at the real program "requirements" in the Proposers' Day Announcement posted at FedBizOps. I downloaded the PDF. At first glance, this seems like a complex way to go about building a Mach 10 aircraft, if that's what you really want. I can't help but feel this is the case of the Air Force engaging in a bit of "Air Forcing". i.e. Gee, we want a Mach 10 aircraft for other reasons but it's too expensive to budget for it using only DoD money for an aircraft with limited to no mission requirement. Hmmm. How do we get others on board? I KNOW, we make it a space launcher! And voila it obtains immediate legitimacy and pays for itself by providing payload to LEO! Yeah, that's the ticket! Now maybe that's not being fair. But I am sure getting that sense of "Air Force Space Shuttle" deju vu all over again... Dave |
#8
|
|||
|
|||
Darpa Revives Larger Reusable Booster Spaceplane
On 9/22/2013 10:17 AM, Anonymous Remailer (austria) wrote:
It's clear that there are some dark political forces at work with the intent of tripping up SpaceX. Not sure that is the motivation here. I'm thinking perhaps DARPA is just looking at either 2nd sourcing against SpaceX, or maybe looking for a way to legitimize funding a Mach 10 aircraft, or maybe SpaceX just simply hasn't applied for any grant money... 2nd sourcing is a phenomena common to commercial industry. It isn't necessarily indicative of any nefarious schemes. Dave |
#9
|
|||
|
|||
Darpa Revives Larger Reusable Booster Spaceplane
On 9/23/2013 9:23 AM, David Spain wrote:.
or maybe SpaceX just simply hasn't applied for any grant money... Or simply hasn't expressed any interest in this program, since this so far appears to be just an unfunded initiative to gauge interest. We know SpaceX has already "expressed" interest in doing at least some aspects of this. There is a slant to the article towards wanting to develop some type of "space plane" or Mach 10 air vehicle, but it is also stated in the article that that is not a requirement. As Robert Clark has already pointed out in commentary after the OP cited article, there exists an option of putting an X37B on some type of reusable booster that might also meet the requirements. To be sure I'd have to check on the cargo capacity of the X37B. The article in the OP mentions delivery of a payload "up to 5,000 lbs for $5M per launch". 10 launches in 10 days being one of them, according to the downloaded pdf I read. A mature Falcon-9R program might be able to achieve that. I haven't run any numbers to see if an X37B/Falcon-9R is doable so I can't say. Also I wonder what is driving the necessity of that 10/10 requirement from a DARPA perspective? Dave |
#10
|
|||
|
|||
Darpa Revives Larger Reusable Booster Spaceplane
http://arc.aiaa.org/doi/abs/10.2514/6.1968-618 http://arc.aiaa.org/doi/abs/10.2514/3.30138 In the 1960s we achieved 5,224 m/sec exhaust speeds with chemical rockets. Basically, you take nanoparticles of fluorine ice along with nanoparticles of lithium and suspend them in a super-cooled mixture of liquid hydrogen. F -219.6 C mp 1.505 g/cc 0.55 H2 -252.9 C bp 0.070 g/cc 0.25 Li +180.5 C mp 0.535 g/cc 0.20 Overall density of 0.232 g/cc To attain the same performance as the Space Shuttle requires a vehicle achieve a delta vee of 9,200 m/sec. A single stage vehicle with a 5,224 m/sec exhaust velocity requires a propellant fraction of; u = 1 - 1/exp(9200/5224) = 0.82814 Now, consider a Super Light Weight Tank for the Space Shuttle: SLWT Specifications Length: 153.8 ft (46.9 m) Diameter: 27.6 ft (8.4 m) Empty Weight: 58,500 lb (26,500 kg) Gross Liftoff Weight: 1,680,000 lb (760,000 kg) LOX tank Length: 54.6 ft (16.6 m) Diameter: 27.6 ft (8.4 m) Volume (at 22 psig): 19,541.66 cu ft (146,181.8 US gal; 553,358 l) LOX mass (at 22 psig): 1,387,457 lb (629,340 kg) Operation Pressu 20-22 psi (140-150 kPa) (gauge) Intertank Length: 22.6 ft (6.9 m) Diameter: 27.6 ft (8.4 m) LH2 tank Length: 97.0 ft (29.6 m) Diameter: 27.6 ft (8.4 m) Volume (at 29.3 psig): 52,881.61 cu ft (395,581.9 US gal; 1,497,440 l) LH2 mass (at 29.3 psig): 234,265 lb (106,261 kg) Operation Pressu 32-34 psi (220-230 kPa) (absolute) Operation Temperatu -423 °F (-252.8 °C)[9] It has a LH2 tank with 1,497,440 l capability and a LOX tank with 553,358 l capability. A total of 2,050,798 l. At 232 grams per liter this has a total capacity of 475,785 kg. Dividing this by u we have a Take off Weight of; TOW = 475,785 / 0.82814 = 574,519 kg. Subtracting off the propellant and structure we have; payload = 574,519 - 475,785 - 26,500 = 72,234 kg Less any additional structure required - e.g. - engine, avionics, etc., plus any savings or removals (intertank, cross-feed, support structure, etc.) A payload of 72,234 kg in LEO requires only 7,750 m/sec delta vee to go to the moon, land, and return to Earth; 2,950 m/sec LEO to TLI 2,400 m/sec TLI to Lunar Surface 2,400 m/sec Lunar Surface to Trans-Earth Injection 7,750 m/sec TOTAL delta vee. So, the propellant fraction here is; u = 1 - 1/exp(7750/5224) = 0.773166 So, with a total weight on orbit of 72,234 kg we have a need for propellant = 72,234 * 0.773166 = 55,849 kg at 232 grams per liter we have a volume of 240,729 liters. Only 0.117383 x the size of the External Tank. This means an miniature external tank only (0.117383)^(1/3) = 0.48963 times the size of the original, will achieve this. Length: 75.3 ft 23.0 m Diameter 13.5 ft 4.1 m Empty: 3,110 kg So, a payload to the moon and back would be; payload = 72,234 - 55,849 - 3,110 = 13,275 kg Now, if we take the propellant mass, and divide it by the propellant fraction needed to attain orbit, we can calculate the payload (if any) this second stage could carry to orbit; TOW = 55,849 / 0.82814 = 67,439 payload = 67,439 - 55,849 - 3,110 = 8,480 kg So, we can see that we can build a smaller vehicle capable of putting 8.4 tonnes (18,656 lbs) into LEO and later, a larger vehicle of the same design capable of putting up 72.2 tonnes into LEO, that carries a second stage capable of placing 13.2 tonnes (29,195 lbs) on the moon and returning it to Earth. The larger SSTO could put up a 1 giga-watt solar power satellite 815 meters in diameter that uses solar powered ion engines for attitude control and to boost from LEO to GEO. The satellite beams 10 MW to 100 ground stations on Earth simultaneously. At $0.11 per kWh the satellite earns $964.26 millions per year. Over a 30 year period the satellite earns $28.9 billions and on the day it begins earning revenue it has a net present value of $12.6 billions. Preselling 100 thirty year energy contracts to 100 buyers in Japan for 10 MW power receivers at a 20% discount over five year construction period obtains $5.1 billions per satellite. Preselling three hundred ground stations for $51 million each obtains sufficient revenues to build the launch system described a fleet of three rockets as well as a supply chain for the launcher and satellite production. Selling five 1 GW satellites per year earns $63 billions per year - more than all the space programs in the world combined. This provides revenue to (1) send astronauts to the moon and mars, and build up capabilities there (2) launch a network of satellites to provide a global wireless hotspot (a) earn revenues from communications, (b) internet services, (c) banking and mediation services, (d) telepresence, (e) telerobotics (3) use additional revenues to expand launcher system and powersatellite size |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
US Air Force cancels Reusable Booster System | [email protected] | Policy | 3 | October 20th 12 04:37 PM |
U.S.A.F Plans Reusable Booster Demonstrators | [email protected] | Policy | 3 | April 15th 10 12:27 AM |
Reusable winged booster X-plane | Pat Flannery | History | 0 | April 4th 09 07:13 PM |
Reaction Engines To Fly Reusable Spaceplane | [email protected] | Policy | 25 | January 17th 09 11:29 AM |
Air Force quick turnaround, reusable booster. | Tom Kent | Policy | 10 | May 7th 05 05:13 PM |