Comments on Selenian Boondocks: Orbital Access Methodologies Part II: The Key Chal...

On the subject of parachutes, have you checked int...

2008-06-17T20:49:00.000-07:00

On the subject of parachutes, have you checked into using a hemisflow hypersonic parachute to reduce reentry loads?

For some reason Google isn't recognizing my password, so I'm posting anonymously.

stickmaker@usa.net

>>>>>Anonymous said... my prediction: Jon is going...

2008-01-23T16:46:00.000-08:00

>>>>>Anonymous said...
my prediction: Jon is going to take a break from the orbital access methodologies discussion and sit speechless for a few weeks, because Mike Griffin just gave a speech about how ESAS was conceived.
PDF link here.

And oh my, its a riot. The common sense and logical conclusions thrown around in there <<<<<

He took a left turn about page 7, but I didn't start screaming at the moniter until page 17. In my experience, people that constantly invoke common sense have the least of it.

my prediction: Jon is going to take a break from t...

2008-01-23T12:19:00.000-08:00

my prediction: Jon is going to take a break from the orbital access methodologies discussion and sit speechless for a few weeks, because Mike Griffin just gave a speech about how ESAS was conceived.
PDF link here.

And oh my, its a riot. The common sense and logical conclusions thrown around in there ..

Jon;Great series I'm looking forward to the next a...

2008-01-22T17:58:00.000-08:00

Jon;

Great series I'm looking forward to the next article!
(Are we 'done' yet? :O)

Seriously, I wanted to mention an air-launch idea I hadn't seen yet, (still making my way through the comments...half the time I can't check out your blog from work... other times I can... damn government filters) Chair-Force mentioned on his blog the Air-Launch methods study done a number of years ago, which I recall having its own method called "SwiftLaunch" which is carried by a large cargo aircraft such as a C5 or AN-225 which I was hopeing to get your comments on?

Secondly, I noted that Mike Puckett asked:
>I wonder if there are any
>potential sites where a recovery
>from a fresh water lake would be
>possible?

I'd think the ram-air/parawing chute would allow that given the right launch azmiths?
While it might be more resrictive in landing sites, it would certianly give Minnisota a "leg-up" for an actual spaceport :o)

I know that ROTON turned a lot of folks off to the idea of rotor recovery, but having read a study on a concept for rotor-recovery for the CEV capsule (using sub-sonic deployed extending blades) I'm wondering what the pros/cons of the idea really are?

I'm personally anticipating the discussion on the idea of "once-around" RTLS booster return. I found an ESA paper on the concept of a first stage rocket plane that used skip-glide with external burning of fuel during the deeper parts of the skip to extend what is basiclly a Mach-12 to 18 speed of seperation (for the second stage) into a once-around-the-Earth RTLS 90 minute flight.
(Mentioned is the fact that such a flight carrying passengers would be a HUGE hit for space tourism folks which is true :o)

I'm also curious on your take on the concept of "Stage-and-a-half" to orbit such as the "Neptune" concept? Something along the lines of a "plug-nozzle" main engine section that is 'staged' and lands down range, especially combined with any of the above ideas seems to be feasible but I'm not a rocket engineer :o)

Keep up the good work!

Randy

::Some gears and feet are needed, which have mass ...

2008-01-22T14:33:00.000-08:00

::Some gears and feet are needed, which have mass and even if the stage is vertical in flight

The simplest solution would be to hang it upside down, so that the expensive parts are up, and have a replaceable crush structure at the other end. Not really reuseable but probably good enough for any near term flight rate.

But note that parawings flare, and can flare very well. With well tuned automatic landing system you can probably land without any significant vertical or horizontal velocity. Deployed skids could be enough.

I think the distinction between "revolution" and "...

2008-01-22T10:40:00.000-08:00

I think the distinction between "revolution" and "evolution" is unhealthy here. IMHO, there's a lot of room for the latter. For example, one can gradually reuse more and more of a launch vehicle as its launch rate increases and the economics start to favor reusability. A revolution on the other hand may fail simply because the business isn't there to support the revolution.

For example, someone pointed me to an extremely ambitious launch vehicle design called the Rombus. Basically, it was a huge reusable SSTO with 450 ton payload using 1960's technology. Would have been revolutionary, if someone had built it. But no market exists for 450 tons to orbit at a frequency and price that would justify such a monster.

And we're getting close to my favored approach: a ...

2008-01-22T02:32:00.000-08:00

And we're getting close to my favored approach: a subsonic flyback with a parawing.
The rocket body can be suspended vertically or any way.

It needs a small turboprop or jet engine to haul it back (can use rocket fuel). Speed is not essential. If it flies high enough, it is not weather sensitive except at landing.

There are huge problems of course: the authorities don't want a big unmanned (although it could be manned as well) parawing dangling a rocket stage flying in their airspace. And how is the final landing done? Some gears and feet are needed, which have mass and even if the stage is vertical in flight, it's probable that it must be landed horizontally if it's a thin cylinder by any measure. The interaction of the canopy, the lines, the rocket and the ground is not entirely simple.
And what happens in gusty or crosswind landing? If the thrust is small and the parawing big, there can be real problems...

Parawing has still the advantage of being remotely...

2008-01-21T12:54:00.000-08:00

Parawing has still the advantage of being remotely steerable, so if you fail to catch, you can choose over which barn to land, to reduce liability issues.
Parawing does not have the center of gravity shift issues that are the achilles heel of VTHL booster ideas, like shuttle flyback liquids.
Iain, the parawing of this size will have its own significant mass to lift as well, so you gotta add some there.
And flying with two ( some redundancy ) at both ends of the booster is also doable.

Of course, packing one would be a b*tch, i hate packing even tandem canopies :)

Jon,A CH-53E can lift 32,000 pounds: http://en.wik...

2008-01-21T12:03:00.000-08:00

Jon,

A CH-53E can lift 32,000 pounds: http://en.wikipedia.org/wiki/CH-53E_Super_Stallion

Presumably it can generate a fair fraction of that lift as forward force.

A paraglider has an L/D ratio of 8:1 or more: http://en.wikipedia.org/wiki/Paragliding

If the CH-53E pulls with 20,000 pounds of force, and the wing is good for 8:1, that's 160,000 pounds lifted. Incredibly, that's only half of an empty Saturn 1C! It is, however, sufficient to move an empty Falcon 9 first stage, or one or even three empty Atlas V first stages.

It seems like a big problem with mid-air recovery is that you must get the stage into a fairly small area to rendezvous with the helicopter/plane. If you have an engine-out abort, it might be hard to arrive in the same area as you would with a normal flight. Perhaps if the normal flight glides back towards base some amount.

But this is getting into the RTLS flyback approach, which you will cover in your next post. I'm looking forward to it.

I think that launch from a coast and powered verti...

2008-01-21T12:01:00.000-08:00

I think that launch from a coast and powered vertical landing on a barge in the ocean would be a good idea.

Of course you can not reach the barge if there is a total propulsion failure in the middle of the flight, but that is what redundant engines are for.

Even when 1000km out, a barge could be towed back to the launch site in a day or so, assuming a tow speed of 25knots. You could check out and refuel the craft while it is being towed back.

You would be limited to one launch per day. But for the time being that is quite a good flight rate.

For smaller, high frequency payloads you could always fly a RTLS maneuver with your first stage. In fact, it might be best to start with a VTVL TSTO that does a RTLS maneuver, and use the barge when you need to double the payload for a space station once the system is reliable.

regards,

Rüdiger

True, if the stage is of decent size, the towing o...

2008-01-21T11:28:00.000-08:00

True, if the stage is of decent size, the towing only helps with the down range part, not the landing...
At which point it starts to resemble flyback.

Gravity Loss,I'm not sure if the trick used for AR...

2008-01-21T09:41:00.000-08:00

Gravity Loss,
I'm not sure if the trick used for ARCTUS could easily be adaptable for a fixed-wing aircraft. As you point out, the stall speed would have to be really low, and you still have to find a way to get the stage to the ground at the end of the flight (unless your slow-flying aircraft can also reel the stage into its cargo bay...).

There are probably ways around the 22klb limit, but I'm not really the guy to ask about it.

~Jon

Mike,Possibly, but then you're really limiting you...

2008-01-21T09:39:00.000-08:00

Mike,
Possibly, but then you're really limiting your vehicle's flexibility. I'll go into this later, but basically I'm shooting for a booster that you could sell a couple dozen of, and have operated all over the world--not just in one or two corner case locations.

~Jon

John,One thing that sort of works with two of your...

2008-01-21T09:38:00.000-08:00

John,
One thing that sort of works with two of your posts is air launching with down range recovery at your main base. Not new of course. Fly some distance uprange to launch downrange toward your base with TSTO first stage recovery at home. Even a modest boost from a few hundred miles has major payload benefits compared to even air launched SSTO.

D'oh! I can't believe I missed that one. Yeah, that makes a lot of sense. You get all of the performance benefits of air launch, all the performance benefits of TSTO, and all of the operational benefits of RTLS...Not to mention, if the upper stage has a failure early in its burn (or right at separation), it will also be coming back right near your launch site.

Methinks I need to add *another* part to my series.

~Jon

Nice stuff!Air catch could be an aircraft towing a...

2008-01-21T08:30:00.000-08:00

Nice stuff!

Air catch could be an aircraft towing a ram air parawing, it doesn't have to be a capture and carry. :)
The aircraft has to be very slow though.
Parachutes have advanced massively in the last 30 years thanks to some crazy American and French adventure guys I guess.

The Arctus team already did a subscale parawing helicopter capture test.
Check the bottom here for video:
http://www.arctus-spacecraft.com/media.htm

Parawing is nice since you can chase it, it doesn't fly straight down like a parachute. Hence the catch velocity difference and shock should be much less. Also low sink rate because it flies forward and has lift and not just drag. You can even flare.

Incidentally I just read about Energia's booster recovery.
http://www.buran-energia.com/energia/energia-consti-1eretage.php
nose forward re-entry with drag chute, then a normal parachute and landing skids for horizontal attitude touchdown! A retro motor in the chute line.

I, like many of you, have watched the stage separa...

2008-01-21T06:56:00.000-08:00

I, like many of you, have watched the stage separation of Saturn Vs. There seems to be a lot of damage to the lower stage when the next stage engine ignites. Not an issue on ELVs.
To make the RLV stage work, it seems to need to be a) strong enough to withstand these forces/heat imposed - more mass/thermal shielding? or b) wait until a sufficient gap has occurred between stages to not get hit by the 2nd stage engine - how much velocity will be lost while this happens/how long do you wait?
Would the additional mass/features/launch profile effect the RLV to an extent to offset any benefit of returned stage. At best you get a returned stage ready for launch after inspection but with reduced launch capability due to the additional strengthening/shielding, at worst you only get the bottom part (engines etc.) to reuse.

I suppose one you has the landing legs/air bags/airbreathing engines/additional fuel for vertical landing/parachutes or whatever for you preferred approach – the additional mass etc to survive separation is not considerable.

Thoughts?

Andy

RTLS with ram-air canopy ala X-38 ? Being a sports...

2008-01-21T04:08:00.000-08:00

RTLS with ram-air canopy ala X-38 ? Being a sports skydiver, i trust my life to these parachutes quite often. With trash pack jobs like we often do, we still achieve about one in 1000 reserve rides. Packed properly, like reserves, they basically always operate.

Nevertheless, the numbers wont probably add up at all for glide back landing. How about ... adding a bit of propulsion ? A huge motored paraglider, bringing back your stage ..
probably in the crazy land, but hey ...

If the recovery downrange is an air catch, then gl...

2008-01-20T13:54:00.000-08:00

If the recovery downrange is an air catch, then glider tow back might mitigate the mass limits. I would assume that a reasonable amount of lifting surface on the recovered stage would allow tow back by an aircraft not much larger than the stage.

How much experience is there on mid air towline catching by gliders?

I wonder if there are any potential sites where a ...

2008-01-20T13:51:00.000-08:00

I wonder if there are any potential sites where a recovery from a fresh water lake would be possible?

One thing that sort of works with two of your post...

2008-01-20T03:56:00.000-08:00

One thing that sort of works with two of your posts is air launching with down range recovery at your main base. Not new of course. Fly some distance uprange to launch downrange toward your base with TSTO first stage recovery at home. Even a modest boost from a few hundred miles has major payload benifits compared to even air launched SSTO.

Sea Launch could use this also. I think this is the same two base thing you said in the post except the launch position would be the minor base instead of the major one.

If you investigate integrating the FLOC concept as well, air launch of really massive payloads might be feasible, on paper.

As a really crazy scheme then, two aircraft fly several hundred miles uprange. They launch two TSTO vehicles, which impart a few thousand m/s to the uppers before doing a first stage recovery at base. During first stage boost, they keep close and the uppers dock after staging for FLOC fuel sharing. The drained upper becomes the only long downrange recoverable asset. It will be much smaller than a first stage and easier to transport home.

I'm glad I don't have a paycheck riding on my hobby class ramblings.