XCOR Aerospace News ?

[space_dreamer]

What’s XCOR Aerospace doing at the moment?<br /><br />They made progress with the Long-EZ but to my knowledge it hasn’t flown since 2002 and there have been no engineering developments or engine firings this year.<br /><br />They were waiting for a license but, they received a Reusable Launch Vehicle mission license from the FAA's Office of Commercial Space Transportation on April 23rd, but since then there has been no news at all. (www.xcor.com )<br /><br />What’s going on?<br />Have they sold any engines?<br />Have they run out of money?<br />Or are they steaming ahead in secret (scaled composite style)?<br /><br />Does anybody have any new information about XCOR?<br /><br />I would love to know what they doing!<br />

 

[spacester]

Great question, it would be great to know. I know there are some great researchers here at sdc hint hint<br /><br />Just going from memory and sheer guesswork . . . <br /><br />I will <b>guess</b> they have retrenched while looking for investors and hope to sell some engines to stay afloat. They are all over the location, location, location thing in Mojave, so there's reason to believe they'll at least survive.<br /><br />The only thing I know for sure is that I wish them the best of luck. <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> </div>

 

[space_dreamer]

I see “Looking for investors”<br /><br />Am I right in thinking Burt Rutan Brother is involved with XCOR?<br /><br />Also I remember Dennis Tito saying that he was ‘ready’ to invest in a sub orbital space plane once the license issues were sorted out. <br /><br />Does anybody know if he is financially backing any of the new space companies yet?<br />

 

[arobie]

Can I have information on that second picture? What is it exactly?

 

[bobvanx]

I was super fortunate to get in to the XCOR open house on June 21. Here's a pic of my son inspecting the EZ Rocket engine. I cleared it with Aleta of XCOR, there was nothing in the hangar that couldn't be shared.<br /><br />In other words, they'd cleaned out a bunch of stuff and hidden it. More in a next post.

 

[bobvanx]

So, here are some bits and dribbles that I can probably share with you, and you can draw your own conclusions.<br /><br />Years ago, Burt approached XCOR to build a 5,000 lb thrust class engine, but they were under a contractual agreement that didn't allow them to talk to him. So he turned to hybrid technology and built SS1.<br /><br />XCOR finished that contract, and Scaled and XCOR started talking about engines. Notice that SpaceDev seems to be using the SS1 experience as a ladder rung rather than promoting it as a core competency. My idea is that SPaceDev knows their days with Scaled are limited.<br /><br />The team at XCOR is *very* busy, and only a couple of them speak in front of Congress. SO the remainder, the rocket engineers, are doing some sort of work that keeps them busy at all hours.<br /><br />XCOR has built their 5,000 lb class engine, and a scalable piston pump (lightweight, works great, scales up to deliver nice high injector pressures).<br /><br />The launch license they've picked up only lasts for a year.<br /><br />When pressed, an engineer answered my question "So are you and Burt working on a future vehicle?" with a big smile and a "I can't tell you, but keep your eyes open."

 

[space_dreamer]

Hi Arobie,<br />The pic is the 400 Lbf engine (LOX-Alcohol) for auxiliary or primary propulsion.<br /><br />Bobvanx,<br />Wow!!!!!!!! So jealous about you going to XCOR. Thank you for that insider info!<br /><br />So the, “XCOR team is *very* busy, the rocket engineers, are doing some sort of work that keeps them busy at all hours”. Excellent! I was concerned that after a good start the company was going the way of way BristolSpaceplanes.<br /><br />Scaled Composites + XCOR = SpaceShipTwo <br />

 

[space_dreamer]

The Isp of the SpaceDev hybrid engine is not very high. <br /><br />If Burt Rutan is planning refit SpaceShipOne with a XCOR rocket engine, the orbital one-man version of SpaceShipOne thread makes much more sense. <br />

 

[space_dreamer]

Ha, so even with the red spray on paint they will need a new space plane. <br /><br />XCORs delta wing design would be better a dissipating the heat than scaled’s bullet with a high wing and double tail shape.<br /><br />How do you think they will solve the heat problem? Tiles, heat resistant paint or some sort of exotic plasma shield? <br />

 

[space_dreamer]

Are there any new composite materials which can with stand the heat of orbital re-entry? Or is the best still way off? <br /><br />I remember someone saying that NASA developed the X33 shape as the most optimum shape for dissipating heat. <br />

 

[space_dreamer]

Sorry i'm being abit thick, what's RCC?

 

[najab]

RCC = Reinforced Carbon-Carbon. It's the hard heat-resistant material that the Shuttle's wing leading edge is made of. That is what the foam hit and apparently broke on STS-107.

 

[mrmorris]

I was (still am actually) curious just how much of a difference the improved ISP would make. Googling around, I found the isp for SS1's current hybrid is said to be about 250, and a similar search for XCOR engines (no telling if it's the *right* one) was about 325.<br /><br />The existing engine boosted SS1 to ~1.25 km/s. Assuming the payload fraction remains unchanged (it wouldn't but we'll pretend), an engine with an isp of 325 would boost the final velocity to ~1.63 km/s. Orbital velocity being about 7 km/s -- there's still a long way to go.<br /><br />Based on the isp of 250 and the final velocity of 1.25 km/sec -- I calculated SS1's payload fraction to be ~.393. Even with an isp of 325, for a one-man SS1 to reach 7 km/sec -- I calculated that they would need to increase that faction to over 88%. This is **not** my area of expertise -- my math is shown below. If I screwed it up -- I'm sure someone here can point out the flaws:<br /><br />Vf = Ve * LN (1/(1-pf)) <br />7000 = 325 * 10 m/s * LN (1/(1-pf)) <br />7000 = 3250 * LN (1/(1-pf)) <br />2.154 = LN (1/(1-pf)) <br />8.62 = 1/(1-pf)<br />.116 = 1 - pf<br />pf = 0.884<br />

 

[space_dreamer]

Ha 'Reinforced Carbon-Carbon' thank you. <br /><br />Is RCC really complicated and expensive to make or can scaled simply subcontract the construction of the all the tiles and it shouldn’t be a problem.<br />

 

[space_dreamer]

Mrmorris, excellent detective work!<br /><br />I suspect that the Isp of a new engine will be more like 340 but I’m just guessing.<br /><br />In my copy of Spaceflight Revolution by David Ashford (Bristol spaceplanes) is says that with modern rockets, A kerosene/oxygen single stage launch vehicle can make a (7.8 Km/sec velocity) 200Km orbit, as long as 94% of the start weight is fuel! <br /><br />However this is launching from the ground, he adds 1.5 Km/sec is lost because of air resistance so the ‘ideal velocity’ is 9.3 Km/sec.<br /><br />However were assuming the that the vehicle is launched from WhiteKnight at (roughly) 800 Kms an hour or 0.222Km/sec, 15Kms above the ground, above 99% of air resistants and were only looking for 7 Km/sec. <br /><br />This is when my useless maths skills become apparent, I’m guessing that SS2 will need to have around 87% of the start weight as fuel to make orbit. <br /><br />That a really tuff challenge but if there anybody who can do it, it’s Burt Rutan.<br />

 

[bobvanx]

>the lack of thermal protection to return from orbit; no way of rejecting internal heat while on orbit etc.<br /><br />One thing Burt is really, really good at is optimizing an engineering solution towards a given set of parameters. One thing NASA is really bad at is optimizing an engineering solution towards a given set of parameters. Actually, it's not the engineers' fault, it's the politics of feeding at the public trough so that everyone with the power to say "no" has to be placated. So we get a refurbishable vehicle rather than re-usable.<br /><br />SS1 is fully optimized to do its one very specific job: win XPRIZE.<br /><br />Burt would bring the same set of engineering savvy to solving the problem of re-usable orbital flight, and while hte actual hardware might look different, it'll evolve from the well-characterized set of tools he's used on every project.<br /><br />i.e., he might find out that he's got to add a little dihedral, or add 2% on a control surface, but the overall vehicle will be very, very capable.

 

[bobvanx]

>this is launching from the ground, he adds 1.5 Km/sec is lost because of air resistance so the ‘ideal velocity’ is 9.3 Km/sec. <br /> <br /> />However were assuming the that the vehicle is launched from WhiteKnight at (roughly) 800 Kms an hour or 0.222Km/sec, 15Kms above the ground, above 99% of air resistants and were only looking for 7 Km/sec. <br /> <br />You can get a real visceral sense of how important the air column is just looking at the SS1 flight test data. Flight 13P and 14P are very interesting. There's only a 15 second difference in thrust times. 13P lit the motor at 38,300 feet and burned for 40 seconds. 14P, which started up at the target altitude of 46,000 (and burned for 55 seconds) reached more than 100,000 feet higher.<br /><br />So 15 seconds more thrust, and 8,000 feet higher start, yielded a 100,000 foot elevation increase.<br /><br />More important, in terms of reaching the required velocity, is that 13P flamed out at Mach 1.6, while 14P flamed out at Mach 2.5. Even on the space flight, the Mach # was just 2.9, but with 20 seconds more boost.<br /><br />So you can see, the air column is a really serious impediment to reaching a high velocity.

 

[bobvanx]

Can you imagine how much it killed him to build the aeroshell for the Roton?<br /><br />I mean, he's a businessman, so he took their money, but I'd wager he went over to his CFD computer and ran the numbers and said to himself, "helicopter blades to stabilize orbital re-entry!?"

 

[bobvanx]

>So you can see, the air column is a really serious impediment to reaching a high velocity.<br /><br />Oh yeah, one more thing. I talked about this with Aleta from XCOR, and she told me that getting up out of the atmosphere as quickly as possible is the preferred flight profile for a reusable orbital or sub-orbital vehicle.<br /><br />So the optimized flight path is to minimize the time it takes to get to 50,000 feet and then optimize the velocity increase from that altitude.

 

[spacester]

Great stuff, bobvanx! Thanks!<br /><br />So much to potentially comment on . . . all in all very exciting!<br /><br /><font color="yellow">So the optimized flight path is to minimize the time it takes to get to 50,000 feet and then optimize the velocity increase from that altitude. </font><br /><br /><img src="/images/icons/cool.gif" /> That's the same thing Carmack of Armadillo is doing, right?<br /><br />I'll check on this thread later, for one thing it looks like we can figure drag losses from the data given on this thread.<br /><br />mrmorris, nice math skills! <div class="Discussion_UserSignature"> </div>

 

[bobvanx]

I Googled for the fuel fraction for Rutan's Voyager aircraft and found this, from The Centennial of Flight website:<br /><br />"Often described as a “flying fuel tank,” the Voyager was outfitted with 17 fuel tanks that carried 7,011 pounds (3,180 kilograms) of fuel—more than 72 percent of its gross weight—at takeoff."<br /><br />So, Burt's already built one vehicle that is very, very close to the required mass fraction.<br /><br />Hee hee, stray thought, but Voyager took 9 days to go around the world once. The same propellant load could allow a sub-orbital vehicle to get anywhere on earth in under an hour. Or to go around the world 144 times in those 9 days.

 

[nacnud]

The new Virgin Atlantic GlobalFlyer has a fuel fraction of 83%

 

[bobvanx]

duncan,<br /><br />thanks for being alert to current events! Say, speaking of staying current, you all know about Alan Radecki's weblog of goings on at Mojave Airport/Spaceport right? He's the eyes on the ground. He'll get pics up of anything going on out there, in better detail than you'll get through a news service.

 

[spacester]

What do y'all suppose are the possibilities of Burt getting rights to the X-33's TPS (Thermal Protection System)?<br /><br />Titanium boxes, easily manufactured, filled with a special insulation and a snap to take on and off, that was good looking technology. IIRC they bolted right onto the aluminum skin of the vehicle. <div class="Discussion_UserSignature"> </div>

 

[spacester]

Long post warning, lol<br /><br />If I did this on a new thread, it would disappear before too long. But I wanted to put this where I could find it . . . so anyway . . . .<br /><br />The difference between Isp = 250 s and Isp = 325 s is HUGE. Mrmorris’ numbers look good, I don’t usually do that particular calc, so it would actually be a bit of work to completely verify, but those numbers and conclusions ring true.<br /><br />Hey kids, want to design a rocketship?<br /><br />Other than specific impulse, payload fraction is everything. Or is that propellant fraction? Man, I still get confused. Where’s that link . . . Ah, good here it is, he defines <br /><br />GLOW = Gross Lift Off Weight = Wp +Wi + WL<br />Wp = propellant weight<br />Wi = inert weight<br />WL = payload weight<br /><br />And then skip ahead a couple slides for<br />V = g*Isp * ln[GLOW/ (GLOW – Wp)]<br /><br />mrmorris, your equation compares nicely, it was<br />Vf = Ve * LN (1/(1-pf))<br />and since Ve = exhaust velocity = g * Isp<br />we see that <br />pf = Wp / GLOW = mass of propellant / total mass at liftoff<br /><br />So we should be saying <br />pf = propellant fraction<br /><br />BTW,<br />Vf = Ve * LN (1/(1-pf))<br />rearranges to<br />pf = 1 - 1 / (e ^ (Vf / Ve))<br /><br />Just wanted to clarify that. Plus pf is a cool little number for rocketship design.<br /><br />Payload fraction would be given by <br />WL / GLOW<br />which is not often used AFAIK<br /><br />And which is not to be confused with<br />Lp = propellant mass fraction<br />Lp = Wp / (Wp + Wi)<br />Lp = how much of your vehicle is propellant before you load the payload<br />This allows you to ball-park a rocketship's mass allocation.<br />Set Lp = 0.8 for starters, and start to figure out Wi<br />By <div class="Discussion_UserSignature"> </div>