Transterrestrial Musings

Comments

From the blog:
"Instead of a C-17, it will be launched from a super-sized White Knight type of vehicle (Rutan's design has not been released to the public.) The crew rides in the CXV capsule."

I previously posted on this here:

http://www.transterrestrial.com/archives/005211.html

Simply eyeballing this off of t/Space's viewgraphs, this aircraft will have a wingspan twice that of a 747 and would be by far the largest aircraft ever built.

Their viewgraphs also state: "Scaled Composites builds for significantly less than cost estimates by primes."

I think there is reason to be skeptical that Scaled can build an airplane far larger than anything built by even a major airplane manufacturer, and do it cheaply.

Posted by Trip Kenner at May 19, 2005 09:03 AM

Wingspan is by itself a terrible measure of how expensive a plane will be. For example, the Virgin Atlantic GlobalFlyer, built by Scaled Composites has a 35 meter wingspan and cost only $2.5 million (it's a very close relative of Rutan's old Voyager plane). That's half the wingspan of the largest 747 and a quarter the wingspan of your estimate of this new plane.

IMHO, this isn't "far larger" than the 747. It'll probably weight a small fraction of the mass of a 747 even when fully loaded with fuel and the launch vehicle or other cargo.

I do see some problems with this plane. First, it'll probably be the largest man-made carbon fiber structure. Second, they may need custom engines for it, I don't know. Finally, it'll be far too big to land at a conventional airport. They might need to make a special runway for this plane (though for testing, they'll probably just use a salt flat).

Still this is the strongest part of Scaled Composites proposal. They know how to build planes. It's ambitious, but I don't see anything that makes this plane design inherently expensive for its size and weight.

Posted by Karl Hallowell at May 19, 2005 04:56 PM

It's not just wingspan. It's the overall size. Look at their little illustration on the viewgraph. The rocket itself is going to be at least 150 feet long. It will be suspended between two fuselages that will be longer than that.

"They know how to build planes."

So do I. You just fold a piece of paper several times and you have an airplane.

You're being silly when you equate "building planes" with building an aircraft far larger than a 747 and somehow doing it cheap.

Posted by Trip Kenner at May 19, 2005 06:00 PM

Yeah. I mean come on. Its just like how nobody could build a space ship for $25 million. Silly folk.

Posted by Dan Schrimpsher: Space Pragmatism Blogger at May 19, 2005 09:30 PM

Hey, Dan, I just looked at your website. I note that it says:

"Dan is the Software Engineering Lead over the Common Data Link Interface for the Army's System of System and a new PhD canidate in Computer Science at the Universtiy of Alabama Huntsville. He is an Auburn Alumni and has been a space enthusiast since he was six."

What is a "canidate"? What is a "Universtiy"? When you applied for graduate school, did you use a spell check?

Posted by Trip Kenner at May 20, 2005 06:51 AM

I should not have stopped there... I looked a little further at your website:

"Okay, let me say up front, I am not a lawyer. But I find this interesting. As far as I can ascertain, two articles in the Outerspace treaty reader it silly."

"reader it silly"? Apparently in addition to not being a lawyer, you're not a writer as well. For someone overflowing with attitude, you don't seem to communicate very well, do you?

Posted by Trip Kenner at May 20, 2005 06:55 AM

As much as it pains me to say it, you are right. I can't spell to save my life. I thought I had ran spell check on everything, but I apparently did not. I applicate the proofreading.

However, what does my lack of ability have to do with the question? A few years ago, many people just like you and me, would have said that no one could build a spaceship (or whatever name you give SS1) for ~$25 million. Scaled did it. Now in addition to not being a lawyer, I am not an airplane designer, but given Burt Rutan's track record, I am willing to give him the benefit of the doubt.

Now what does on the cheap mean? According to A history of the 747, development costs were over $1 billion dollars (in 1969). So accounting for inflation, that is about $5.3 billion in todays dollars. So based on that, if Burt can build a VLA for far less than that, say $100 million, he could reasonably say it was "on the cheap"

No whether that is cheap enough for t/Space remains to be seen.

Posted by Dan Schrimpsher: Space Pragmatism Blogger at May 20, 2005 07:42 AM

Ironically it took Boeing $8B (and some say more like $10B when you account for all the R&D that wasn't) to build the smaller 777. Of course, with the 747 they didn't have all of the productivity enhancing personal computers, CFD, 3D CAD, etc.

I would say you are missing the fatal flaw in their plan by discussing whether or not this or that company can build a big airplane. The big problem here is the parachute. They are great for reentry, but why would you want to put a rocket in an airplane and then slow it down, in fact, give it negative velocity, before lighting the engines? That's a lot of trouble to go to just for some additional altitude.

It's pretty clear to anyone who has even run some cursory equations that launch altitude means almost nothing when it comes to putting a vehicle on-orbit. Velocity is everything. What they really need is a big airplane with either a huge big bomb bay or a separable portion of the vehicle like the bomb pod on a B-58.

There are a lot of good launch ideas out there, this is not one of them.

Posted by Dfens at May 20, 2005 08:16 AM

That is interesting. So would spaceshipone have required less "energy" to start from a runway? I wouldn't have throught so, but maybe so.

Posted by Dan Schrimpsher: Space Pragmatism Blogger at May 20, 2005 09:21 AM

Schrimpsher wrote:
"However, what does my lack of ability have to do with the question?"

You keep flacking your website, and I keep pointing out that it's not written very well. How are you going to communicate any ideas if every single paragraph has at least one typo or grammar mistake?

And I find the substance of your comments equally lacking. This would be the largest aircraft in the world, by far. At the very least it would require a massive assembly hangar. And yet we're supposed to believe that Scaled has the ability to do this better than everybody else?

Posted by Trip Kenner at May 20, 2005 09:41 AM

Quote: "yet we're supposed to believe that Scaled has the ability to do this better than everybody else?"

Yes!

Posted by Josh Reiter at May 20, 2005 10:35 AM

Quote: "I would say you are missing the fatal flaw in their plan by discussing whether or not this or that company can build a big airplane. The big problem here is the parachute. They are great for reentry, but why would you want to put a rocket in an airplane and then slow it down, in fact, give it negative velocity, before lighting the engines? That's a lot of trouble to go to just for some additional altitude."

It took me two seconds of looking at the website to see that the AirLaunch system has just been linked to as an example. There is no indication that parachutes will be used in the Scaled Composites concept. Only reason that AirLaunch needs them is as a drogue to drag the launch vehicle out of the back of the aircraft through the rear cargo doors of the C17. In fact, no one really knows what Scaled is up to or what the end product will look like at this point.

Posted by Josh Reiter at May 20, 2005 11:41 AM

"That is interesting. So would spaceship one have required less "energy" to start from a runway? I wouldn't have thought so, but maybe so."

No, Spaceship 1 was dropped like a missile might be. Thus when it lit it's engines, it had the advantage of the forward velocity given to it by the mother ship.

Rocket engines are extremely inefficient at slow speeds. Most efficient lift is generated by accelerating the largest practical amount of air (gas) the smallest amount required. That's why a slow airplane, like a glider, has a very long, high aspect ratio wing. On the other end of the airplane spectrum would be a fighter with a low aspect ratio wing.

Rockets are far to the fast end of the spectrum both because their engines typically develop lift by accelerating a small amount of gas to incredible velocities, but also, naturally, because they carry their own oxidizer.

Posted by Dfens at May 20, 2005 03:55 PM

Size is not the issue here, folks. Weight is. A fully laden 747 tips the scales at upwards of 500 tons. t/Space's VLA may have a huge wingspan, but it's not going to be very heavy, given its dimensions. Why? Because it won't have:

1. 500 passengers and two dozen crew.

2. 100+ windows in the fuselage.

3. a completely padded and "finished" interior.

4. seats and carry-on luggage bins for 500 passengers.

5. cargo holds for checked luggage for 500 passengers.

6. the checked luggage of 500 passengers.

7. air conditioning suitable for 500 passengers.

8. auxiliary power to run said air conditioning during flight holds on the ground.

9. emergency oxygen for 500 passengers.

10. emergency exit doors and slides to handle 500 passengers in 90 seconds.

11. emergency life rafts for 500 passengers.

12. food, drinks and snacks for 500 paseengers.

13. galleys to warm 500 meals at once.

14. serving carts to trundle 500 meals, plus drinks to the passengers.

15. 8 or 10 bathrooms with running water and flush toilets.

16. black water holding tanks to support same.

17. a frame full of massive bulkheads and longerons made of metal.

18. a metal skin.

19. 5 million flush rivets holding the whole shebang together.

20. massive landing gear suitable for landing a 500 ton plane at 125+ kt.

21. massive actuators to retract and deploy said gear.

The VLA looks to be basically a combination of White Knight and Global Flyer-type pieces, scaled up by a rough factor of four. Those two big "fuselages" are fuel tanks. The real fuselage is that small bit above the underslung payload. It'll have a spartan crew cabin for two in the nose. The rest is either more fuel or empty space. The whole beast, even with a full fuel load and a CVX and booster slung underneath will come in at a fraction of 500 tons.

Like the White Knight and Global Flyer, the VLA will also have leisurely rotation and landing speeds due to wing length and low wing loading. Landing gear will be small and probably fixed - maybe placed along the centerlines of the two fuel tanks like an oversize in-line skate.

Engines and nacelles - maybe even the pylons - will be off-the-shelf units from some extant jumbo or other. Having four is probably more for safety on long over-water flights than for takeoff power. They'll loaf during most of a typical mission profile.

Can Scaled Composites build such a thing?

Standing on their heads.

Posted by Dick Eagleson at May 21, 2005 06:54 AM

"Can Scaled Composites build such a thing? Standing on their heads."

I agree. However...

"It's pretty clear to anyone who has even run some cursory equations that launch altitude means almost nothing when it comes to putting a vehicle on-orbit. Velocity is everything. What they really need is..."

Seems reasonable. I don't think anyone would suggest launching a shuttle off the back of a 747.

It would seem to me that back of the envelope calculations would be able to answer the question of what's a prefered design at the outline level. I also imagine Rutan is pretty good at that sort of thing. SS1 was a fantastic achievement, but mostly because it may have turned some heads and changed some attitudes... not because it's the best design. The important part of the design in my opinion is the shuttlecock reentry rather than the white knight sendoff (which of course is cool.) Could that reentry method work coming down from orbital speeds? If so, isn't that the breakthrough?

Posted by ken anthony at May 21, 2005 07:40 PM

t/Space has numeous reasons for launching at 25,000 altitude. One includes the ability to ignore the need to build pumps that are efficient at sea level air pressure.

Ar ISDC I saw an animation of the launch. The rocket "falls" before igntition - - velocity has nothing to do with the decision to launch at 25,000 feet since all velocity imparted from the carrier plane will be lost to gravity.

All weather launches are another reason. T-storms? Fly above the cloud cover and launch. Abort? You already are at 25,000 feet. No escape tower needed - - meaning less weight on the vehicle.

Simple pressure fed rocket motors (no need to be efficient at sea level) are simpler, cheaper, more reliable and lighter. All good, no?

Link:

http://64.78.33.215/index.cfm?fuseaction=projects.view&workid=CCD3097A-96B6-175C-97F15F270F2B83AA

I am normally skeptical of alt-space claims.

However, I believe t/Space will be successful if they are permitted to be successful by our government.

Posted by Bill White at May 22, 2005 07:07 PM

"The t/Space version of air launch provides only modest performance gains, in the 10-25% range, compared to a ground launch."

Thanks for the link. The higher the release speed, the bigger the performance gain. They seem to have had their hands full trying to overcome the compressibility problems between the tanks and the rocket in their VLA design. It brings to mind the P-38. It would seem hanging them down that far would create an unnecessarily high risk of a strike during a drop. There are better ways to deal with compressibility.

Posted by at May 22, 2005 08:02 PM

Another interesting feature is the flexibility to insert in a variety of orbits. Ie, it really opens the launch window, if you need to put something in a difficult orbital configuration. The most extreme examples of this (as I gather) are filling the last slots of a constellation of satellites. I once attended a (non)launch at JFK Space Center where the rocket had a two hour window once or twice each *month* to fill a particular slot. In that case, they had a hydrogen leak and had to postpone the flight till the window appeared again next month.

But with air launch you at least can widen that window of opportunity.

Posted by Karl Hallowell at May 23, 2005 08:46 AM

Someone writes: There are better ways to deal with compressibility.

= = =

During ISDC, I heard one of the Virgin Galactic executives say that he was standing next to a former RAF test pilot when SS1 started spinning. That RAF test pilot was said to have said: "[colorful British explictive] - - They need yaw dampers on that thing!"

The executive then said that the Virgin Galactic version will have yaw dampers. I would expect t/Space to follow the same approach - - modify as needed after flight testing.

The key to the t/Space approach appears to be a tight focus on mission. Crew to LEO and NOTHING more. Form follows function.

And a mixture of reuseable and expendable. If cheap enough expendable is better than reuseable.

Think Bic pens versus Cross pens.

Posted by Bill White at May 23, 2005 09:18 AM

They'll need yaw dampers on their vehicle concept if they're going to keep those big tanks from fluttering. Putting that much torque through those long pylons is going to be quite a trick. They would have been better off to either deal with the compressibility issues in a more direct manner, or to use the tanks to fillet the area between the rocket and the wing. There will be a lot of dead flow in that region the way their concept is currently.

It's funny, but had Kelly Johnson not had the compressibility issues he had with the P-38, he would not have been able to make the SR-71 the success it was. I have often thought a Mach 2 mother ship would be cool. The Saturn V used half it's fuel getting to Mach 2. It used the other half to go 12 times faster than that. There's not really anything magical about Mach 2, but it would allow the vehicle to be built out of aluminum instead of Ti or steel. It may also allow for use of fixed geometry inlets.

There are no good airplane designers any more. I know one, he's in his mid-50s. There are two more I know by reputation who are highly paid consultants. I think they are about the same age. It's a sad state of affairs.

Posted by Dfens at May 23, 2005 03:45 PM

I have often thought a Mach 2 mother ship would be cool. The Saturn V used half it's fuel getting to Mach 2.

Next generation, perhaps?

Posted by Bill White at May 23, 2005 05:18 PM

I have a small spark of hope left.

Posted by Dfens at May 24, 2005 05:38 AM

"There are no good airplane designers any more. I know one, he's in his mid-50s. There are two more I know by reputation who are highly paid consultants. I think they are about the same age. It's a sad state of affairs."

You have to be kidding. Rutan is one of the greatest aircraft designers of all time. I've been following his work since he bailed out Jim Bede's design flaws in the BD-5, through his brilliant Varieze and Long-Eze designs, the rise of Scaled Composites, the Voyager, SpaceshipOne, etc.

Anyone who is willing to come out and throw cold water on Rutan's design by just making snap off-hand judgements on this board without knowing all the engineering details is displaying a remarkable level of hubris.

Rutan has earned the benefit of the doubt.

Posted by Dan H. at May 24, 2005 10:26 AM

There is a certain threshold of knowledge you have to possess to be able to recognize those who truly stand out. What I find sad is that this threshold of knowledge is absent within the aerospace community. This too is part of the rise of the program in aerospace. Do you think the program manager of C-17 wants to wake up one day and find out that someone in his own company knows how to build a cargo airplane that's cheaper, faster, and more efficient than his? Heck no, it threatens his rice bowl. It's the same way at NASA with shuttle and many of their other programs.

I'm not taking anything away from Rutan's accomplishments, but he is not in the same league with the handful of what I consider to be the true aircraft designers in the US. If you don't know what's possible, you can't see what's missing.

Posted by Dfens at May 24, 2005 06:38 PM

Post a comment