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Horizontal vs Vertical

Posted by: FerrisValyn - Fri Jun 01, 2007 2:04 am
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Horizontal vs Vertical 
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Post Horizontal vs Vertical   Posted on: Fri Jun 01, 2007 2:04 am
Was at ISDC last week, and went to some talks about spaceports. I didn't see them all. However, between the ones I did see, and this recent post by Mr Foust I've been struck by the seem to be focus on HTHL vehicles for spaceport use. I remember Mr. Carmack talking about Oklahoma spaceport not having the certifcation for VTVL crafts - so Im wondering, with this focus on HTHLs, how would a spaceport specifically designed for Vertical style crafts be different - consider any and all angles - regulatory, construction, management, etc

Thougths?


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Post    Posted on: Fri Jun 01, 2007 9:41 am
Well most obvious I guess would be the lack of a runway, you'd need something resembling a monster-sized helipad.

At a practical level I guess with a vertical landing rocket there'd be problems with ground-blast around the launch site, you'd need safe zones for horizontal motion with nothing on the ground that could be harmed by the exhaust. You'd also need a ground surface for the pad capable of withstanding the exhaust blast, the exploding concrete you see in armadillo's longer hover tests would indicate this is a harder thing than you'd expect.


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Post    Posted on: Fri Jun 01, 2007 3:00 pm
Maybe I am biased from having flown fix wing aircraft, but rocket planes with wings just seem way safer than rockets without them. For a plane, you need a long runway with some open space for safety beyond the end, but you need much less open space at the sides of the runway because the plane is not moving in that direction, and is very unlikely to turn in that direction. You never see the terminal right off the end of the runway with the planes flying right over it; it is always off to the side where it is safe. And if you shut down the engine, the plane can still control its flight with its winds and control surfaces.

Now a vertical flight rocket normally just goes straight up, which is all fine, but if there is any problem, it can go off in any direction. In effect, everyplace around the launch pad is equally dangerous. There is no segregation into the safe area beside the runway and the dangerous area off the ends of the runway. Also, if the rocket engine shuts down, the vehicle will just fall like a rock. You will not even be able to control where it falls since all control comes from the operating rocket engine.

So basically, there is no difference between a HTHL space port and a regular airport. And there is no difference between a VTVL space port and an artillery range, except that in normal circumstances the cannons are pointing straight up or nearly straight up. But for safety reasons you have to assume that they could point sideways at any moment.


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Post hthl vs. vtvl   Posted on: Fri Jun 01, 2007 7:43 pm
I'm biased towards HTHL for manned suborbital missions and VTVL for unmanned.

The abort sequence for HTHL (two stage - air dropped) is far more forgiving than VTVL. VTHL (e.g. shuttle) is a compromise between the two, but not a very good one. HTHL is the safest, but not the most efficient or capable (no HT to orbit yet). HTVL doesn't make sense (unless you're in a small aircraft with an emergency aircraft parachute!).

Assuming you can shut off your engine (ie. not a solid), with HTHL, you can glide back to your recovery area. Liquid engines allow for rapid refill (assuming it wasn't a hardware failure that led to the abort). I'd have to see the turn around on a hybrid engine to believe that it was just as fast (not saying it can't be though). Hybrids do buy some safety margin that might lead to improved turn around vs. LOX.

Personnaly, I think that Space Ship Two is the best design for safety. This is primarily because of the forgiving abort sequence after air drop from WK2. I'd love to see SpaceDev's Dreamchaser (or whatever it's latest incarnation will be) air dropped for suborbital tourism. A stacked booster is tougher to process and has less forgiving abort (need to clear the booster with sufficient height/speed to glide to safety). Both have hybrid fuel, which is safer to handle than liquids, though liquids can be drained and replaced much faster (e.g. Falcon 1 flight 2).

As for unmanned VTVL, until someone comes up with the magical HTHL to orbit (SS3?), this is currently the only way of getting into orbit. Abort squence for any post-liftoff VT is inherently more difficult than HT. VT, however, kicks the socks off ANY HT for payload.

Anyway, back to spaceports. Smaller, trully commercial spaceports far away from legitimate military ranges will have serious overflight issues for VT. HT is inherently safer and you don't have as serious overflight issues (you can fly to a range that may be away from the spaceport.) With VT, your spaceport must be at the range. Spaceport America can handle both HTHL and VTVL due to its proximity to White Sand Missile Range. Other spaceports will need to be located next to an existing missile range or create their own (good luck). Spaceports located next to large bodies of water might be a good compromise as long as there is not a lot of traffic on the water (which is often a problem in Florida).

You think there is a reason that SciFi writers overwhelmingly show HTHL SSTO spacecraft? I think they might be on to something. We just need that magical efficient propulsion system that can handle SSTO HTHL.

Alistair

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Post    Posted on: Sat Jun 02, 2007 4:13 am
Well right now I'm personally interested in lifting body designs for suborbital or 2 stage to orbit designs. A lifting body would share many of the advantages of both sides of the argument:

- The ability to launch vertically like a rocket but land horizontally.
- Higher drag than a standard rocket but much more structurally efficient than a standard aeroplane.
- Huge internal volume, allowing for some high mass ratios.

When you think about it, your lifting body doesn't even need to generate enough lift to land horizontally, just enough to gain some element of control over the decent:



What are the biggest problems with capsules and parachute based re-entry systems? It's hard to predict where you're going to end up landing, and so you need huge landing zones with a fleet of recovery vehicles and the regulations for a parachute based landing are hell for any private company.

On the flip side of HTHL you can avoid a huge legal mess and very accurately land your vehicle, cutting out the huge tracts of recovery land and personnel. HTHL vehicle design is however restricted by aerodynamic geometry requirements, your vehicle has to generate enough lift to land horizontally and be controllable enough to do so, most likely this will require compromises in drag, structural efficiency and mass ratio.

With a VTVL design you have the structural and drag advantages of a rocket with the landing zone requirements of a horizontal landing design, but the landing system is very failure prone, there's simply no engine or system-out capability with a simple design, and if you complicate the vehicle enough for these abilities then you compromise on weight and simplicity.

It is my idea to combine the advantages of a parachute system with that of a horizontal landing system. A lifting body with just enough lift (1:1 lift to drag ratio or even less), you dive the lifting body almost straight down while using the aerodynamic control characteristics of the vehicle to manoeuvre yourself much closer to the landing site. Then when you're a few thousand feet up you rapidly increase angle of attack to bleed off speed and deploy parachutes. In this situation your maximum drift distance is very low because the parachutes are deployed very close to the ground, while the landing area uncertainty is also very low because you were able to steer the vehicle in. Also the vehicle has less stringent aerodynamic requirements because you only need a very low lift to drag ratio and so you're free to further optimise structural efficiency etc.


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Post We're getting off topic guys   Posted on: Sat Jun 02, 2007 4:40 am
I've seen/heard the back and forths on whether to go VTVL, HTHL, and all that are in between.

I am really more interested in the spaceports aspect. What/how do you see things developing differently VTVLs (and here I am refering to things like Blue Origin and Armadillo and Masten - not parachute based systems) for spaceport development vs a spaceport designed specifically for HTHLs?


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Post Re: We're getting off topic guys   Posted on: Mon Jun 04, 2007 5:24 pm
FerrisValyn wrote:
I've seen/heard the back and forths on whether to go VTVL, HTHL, and all that are in between.

I am really more interested in the spaceports aspect. What/how do you see things developing differently VTVLs (and here I am refering to things like Blue Origin and Armadillo and Masten - not parachute based systems) for spaceport development vs a spaceport designed specifically for HTHLs?


Again, a VTVL needs a lot more range clearance than HTHL given the different launch profiles and abort sequences.

I think VTVL spaceports will be at geographically isolated locations or at locations with large bodies of water due east of the launch point. HTHL can fly from almost anywhere, though, a nearby, relatively clear (smaller) range is useful when the reliability of the vehicles is still in question.

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Post    Posted on: Mon Jun 04, 2007 6:30 pm
Quote:
Again, a VTVL needs a lot more range clearance than HTHL given the different launch profiles and abort sequences.

I think VTVL spaceports will be at geographically isolated locations or at locations with large bodies of water due east of the launch point. HTHL can fly from almost anywhere, though, a nearby, relatively clear (smaller) range is useful when the reliability of the vehicles is still in question


A couple of points -
First, launching east for sub-orbital flights doesn't really add anything (you dont' get more payload higher or anything - the most you might be able to gain is travel time if you doing point to point travel, but don't hold your breath for that, and don't expect point to point to happen soon), so I don't see any reason you'd want water on your east side.

Second, what about the fact that helipads and heliports are quite common? Vehicle's like the Armadillo's Quad and Blue Origin's Goddard or New Shepard are closer to Helicopters (rather than, as camphelp2002 argued, to artillery).

I do think its a little disengenous to veiw something like the Quad or Goddard as being the same as the Falcon 1 - they both have very different profiles.

I do feel that while the current plane regime of regulations will ultimatly largely translate nicely to HTHL vehicles, a whole new set of regulations will need to be figured out for VTVL vehicles.


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Post    Posted on: Wed Jun 06, 2007 3:20 pm
Ferris,
Just some random thoughts.

For a VTVL spaceport, like any other spaceport you're going to want it far away from anything else of value. Like at least several miles from population of any kind.

Second, you really don't want to have large numbers of tenants unless their facilities are either underground or sufficiently hardened that a worst-case landing mishap can't damage them. If "multiple conspiring demons" can crash a VTVL vehicle into another tenant's hangar, but all the hangars are sufficiently beefy to take a direct hit, it'll be a lot easier to get insurance and regulatory permission to fly.

As for layout of the site, I'd imagine you'd want one or more pads a long distance from the hangars. Say 1km or so. The pads would likely just be concrete with minimal infrastructure. Maybe some sort of umbilical hookups eventually for power, fuel, oxidizer, and data. You're unlikely to need or want any sort of launch towers.

Honestly, short term, all a VTVL spaceport really needs is a fenced off area covering a couple of square miles with a concrete pad (say 40x40') out in the middle. Everything after that is just gravy.

Sorry if that's random.

~Jon


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Post    Posted on: Thu Jun 07, 2007 5:40 am
FerrisValyn wrote:
First, launching east for sub-orbital flights doesn't really add anything (you dont' get more payload higher or anything - the most you might be able to gain is travel time if you doing point to point travel, but don't hold your breath for that, and don't expect point to point to happen soon), so I don't see any reason you'd want water on your east side.


You're right, I was thinking orbital.

FerrisValyn wrote:
Second, what about the fact that helipads and heliports are quite common?


Still need more area for VTVL. A small, simple explosion can still kill at a couple hundred yards. Worst case scenario, I'd think you'd want at least a mile clearance from the pad for a suborbital rocket. Increase for a bigger rocket. Also increase depending on over flight once it leaves the pad.

Thus, VTVL will still need some range clearance (though not necessarily due east). Debris doesn't fall straight down, so large clearance areas are still needed.

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Post    Posted on: Thu Jun 07, 2007 12:42 pm
alistair wrote:
FerrisValyn wrote:
First, launching east for sub-orbital flights doesn't really add anything (you dont' get more payload higher or anything - the most you might be able to gain is travel time if you doing point to point travel, but don't hold your breath for that, and don't expect point to point to happen soon), so I don't see any reason you'd want water on your east side.


You're right, I was thinking orbital.

FerrisValyn wrote:
Second, what about the fact that helipads and heliports are quite common?


Still need more area for VTVL. A small, simple explosion can still kill at a couple hundred yards. Worst case scenario, I'd think you'd want at least a mile clearance from the pad for a suborbital rocket. Increase for a bigger rocket. Also increase depending on over flight once it leaves the pad.

Thus, VTVL will still need some range clearance (though not necessarily due east). Debris doesn't fall straight down, so large clearance areas are still needed.


And what if your HTHL rocket decides to blow himself up on the runway? The blast will have as much energy as an VTVL vehicle so you would need a mile of clearance along the length of your three mile long runway. So for take-off your safety area is allready much larger than the safety area for a VTVL vehicle. And when your HTHL vehicle leaves the runway it doesn't go straight up but will also go a considerable horizontal distance. So you need an additional amount of safety area.
Certainly for suborbital rockets the range clearance will be much smaller for VTVL's because they go just straight up. And if something goes wrong it just drops straight down. HTHL will travel a considerable horizontal distance and when your HTHL guidance system fails, you could travel alot further because of the wings. So i have serious doubts that the range clearance for a VTVL vehicle would be bigger than for a HTHL vehicle.


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Post    Posted on: Thu Jun 07, 2007 12:52 pm
Hello, Soyuz,

that seems to depend on the HTHL-concept - the vehicle might be designed so that it applies airplane engines on the runway at launch, switches over to rocket engines high in the air, gets into the space, leaves the space later again and switches over to airplane engines again at a certain altitude above and distance tot the runway to apply airplane engines on the runway.

At such a concept the HTHL will not blow up on the runway.

...



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Post    Posted on: Thu Jun 07, 2007 1:13 pm
If it is the fact that a rocket engine is being used, then the EZrocket should need a spaceport. If the rocket engine isn't even ignited until the launch aircraft is at the launch location, as with SS1 or Pegasus, then the safety at the spaceport/airport is not really impacted. I think the whole idea of requiring special clearance for WK/SS1 to take off from Mojave as compared to any other flight is silly. It should only be the airspace where SS1 ignites its engine that is controlled. The same should apply to Pegasus. If there were something like HOTOL, then I would agree that extra margin would be needed. http://www.astronautix.com/lvs/hotol.htm


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Post    Posted on: Thu Jun 07, 2007 2:50 pm
I just wanted to point out that VT rocket powered vehicles are not really like helicopters. If a helicopter has an engine failure they can land without power by autorotation. The higher and faster the Helo is the better it's chances for a successful unpowered landing. :)

http://en.wikipedia.org/wiki/Autorotation


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Post    Posted on: Thu Jun 07, 2007 3:30 pm
I agree that a helicopter is different, but not because it can autorotate, or at least not only for that reason, but because it is slower. Rockets are dangerous not because they go straight up, but because they go so high and fast. Armadillo was limited to something like 15 seconds of fuel for their early tests for that reason. The FAA assumes that the rocket could go out of control and crash at maximum range. At the speed of a helicopter, that isn't far, but at the speed of a rocket, it could be really far.


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