Author Topic: Impact of Stratolaunch on F9 demand 5-10 years from now  (Read 28650 times)

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28759
  • Minnesota
  • Liked: 8869
  • Likes Given: 5743
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #40 on: 12/19/2011 03:11 pm »
What DARPA does doesn't always mean the rest of the DOD wants it or is ready for it.
True. But there's a potential desire for such a capability.
Does DoD have payloads for launch on 24hs notice? Are they developing them? I'm truly intrigued (though I would be highly surprised if any of the answers was yes).
Not yet. More of a "want" than a present capability.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline baldusi

  • Senior Member
  • *****
  • Posts: 7438
  • Buenos Aires, Argentina
  • Liked: 1459
  • Likes Given: 4518
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #41 on: 12/19/2011 03:53 pm »
What DARPA does doesn't always mean the rest of the DOD wants it or is ready for it.
True. But there's a potential desire for such a capability.
Does DoD have payloads for launch on 24hs notice? Are they developing them? I'm truly intrigued (though I would be highly surprised if any of the answers was yes).
Not yet. More of a "want" than a present capability.
Want or desire? Want means that they are constantly keeping an eye on the capability. Desire means that they would accept it, and would even pay a premium for it, but it's completely out of their efforts.

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28759
  • Minnesota
  • Liked: 8869
  • Likes Given: 5743
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #42 on: 12/19/2011 04:11 pm »
Would-like-to-have, at least right now. Not a must-have.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline RanulfC

  • Senior Member
  • *****
  • Posts: 4446
  • Heus tu Omnis! Vigilate Hoc!
  • Liked: 814
  • Likes Given: 32
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #43 on: 12/19/2011 04:20 pm »
We can only comment on what was presented which shows a crewed carrier aircraft.  If is to be then ethically they need to be protected with means of escape in some form.

While I can in general "agree" with your point, reality tends to negate "ethical" considerations :)

When was the last time you were handed a parachute and instructions on a cross-country commercial airliner? Has anyone ever informed you that the airline companies have knowingly put you in danger of serious injury on every flight simply because they refuse to turn the seats 180-degrees as the DoD pointed out 60 years ago?

It's possible they might set up the carrier aircraft to be optionally manned but the flight testing will be manned. Some risks you take and live with.

I tend to look at this operation more along the lines of the X-1, X-2 and X-15. If your look back at their problems during their flight history you can see my concerns. From in-flight fires and explosions and this will be at a much larger scale.  Just things to consider while still matedÖ
Actually your not "helping" your case that much :)

How many carrier aircraft did we lose during the test programs? Any issues while still attached and it is "safe" to do so you just jettision the LV. The way they are discussing abort options it's likely they will be working with both manned and unmanned intact abort even if they have to jettision the LV. And it would seriously have to be a "bad-day" to get to that point.

Given Space-Xs work on isolating and shielding the engines (and the 5-X config has a LOT more room to work with for shielding) even an engine explosion would probably not result in the loss of the LV as long as it was still attached to the Carrier Aircraft.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Rocket Science

  • Senior Member
  • *****
  • Posts: 9219
  • NASA Educator Astronaut Candidate Applicant 2002
  • Liked: 3068
  • Likes Given: 8345
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #44 on: 12/19/2011 04:29 pm »
We can only comment on what was presented which shows a crewed carrier aircraft.  If is to be then ethically they need to be protected with means of escape in some form.
While I can in general "agree" with your point, reality tends to negate "ethical" considerations :)

When was the last time you were handed a parachute and instructions on a cross-country commercial airliner? Has anyone ever informed you that the airline companies have knowingly put you in danger of serious injury on every flight simply because they refuse to turn the seats 180-degrees as the DoD pointed out 60 years ago?

It's possible they might set up the carrier aircraft to be optionally manned but the flight testing will be manned. Some risks you take and live with.

I tend to look at this operation more along the lines of the X-1, X-2 and X-15. If your look back at their problems during their flight history you can see my concerns. From in-flight fires and explosions and this will be at a much larger scale.  Just things to consider while still matedÖ
Actually your not "helping" your case that much :)

How many carrier aircraft did we lose during the test programs? Any issues while still attached and it is "safe" to do so you just jettision the LV. The way they are discussing abort options it's likely they will be working with both manned and unmanned intact abort even if they have to jettision the LV. And it would seriously have to be a "bad-day" to get to that point.

Given Space-Xs work on isolating and shielding the engines (and the 5-X config has a LOT more room to work with for shielding) even an engine explosion would probably not result in the loss of the LV as long as it was still attached to the Carrier Aircraft.

Randy
Randy,
All I am saying is that this system should be considered an experimental  and not to rush to deem it operational right off the bat. This was one of the many lessons learned fron Shuttle.

Regards
Robert
« Last Edit: 12/19/2011 04:30 pm by Rocket Science »
"The laws of physics are unforgiving"
~Rob: Physics instructor, Aviator, Vintage auto racer

Offline HMXHMX

  • Full Member
  • ****
  • Posts: 1587
  • Liked: 1569
  • Likes Given: 416
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #45 on: 12/20/2011 02:05 am »
Stratolaunch's advantage is claimed to be in its flexibility to reach "any orbit, any time." This is especially useful in rendezvous missions to ISS where the carrier aircraft can alter its launch point at short notice to extend the launch window available. But for the launch of most commercial payloads this flexibility seems less necessary.
Would there be any demand from the DoD for a just-in-time launch service?
Yes, I would imagine there would be. Another previous air launch concept (called QuickReach by Airlaunch LLC) received funding from DARPA's FALCON program which had a requirement to launch within 24 hours of notice. The larger (manned) variant (QuickReach II) of this also proposed using something remarkably similar to the Stratolaunch carrier aircraft. It was supposed to be about as big and also built by Scaled Composites. There's lots of inbreeding in the aerospace sector.

What DARPA does doesn't always mean the rest of the DOD wants it or is ready for it.

Don't I know it.  I still have the tread marks across my back from that one.  Even with their signatures on an Agreement with DARPA, USAF managed to weasel out of it.
« Last Edit: 12/20/2011 02:07 am by HMXHMX »

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28759
  • Minnesota
  • Liked: 8869
  • Likes Given: 5743
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #46 on: 12/20/2011 03:59 am »
Stratolaunch's advantage is claimed to be in its flexibility to reach "any orbit, any time." This is especially useful in rendezvous missions to ISS where the carrier aircraft can alter its launch point at short notice to extend the launch window available. But for the launch of most commercial payloads this flexibility seems less necessary.
Would there be any demand from the DoD for a just-in-time launch service?
Yes, I would imagine there would be. Another previous air launch concept (called QuickReach by Airlaunch LLC) received funding from DARPA's FALCON program which had a requirement to launch within 24 hours of notice. The larger (manned) variant (QuickReach II) of this also proposed using something remarkably similar to the Stratolaunch carrier aircraft. It was supposed to be about as big and also built by Scaled Composites. There's lots of inbreeding in the aerospace sector.

What DARPA does doesn't always mean the rest of the DOD wants it or is ready for it.

Don't I know it.  I still have the tread marks across my back from that one.  Even with their signatures on an Agreement with DARPA, USAF managed to weasel out of it.
Yeah, I was very disappointed that your approach wasn't allowed to continue.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline alexterrell

  • Full Member
  • ****
  • Posts: 1653
  • Germany
  • Liked: 98
  • Likes Given: 71
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #47 on: 12/24/2011 12:49 pm »

Stratolaunch's advantage is claimed to be in its flexibility to reach "any orbit, any time." This is especially useful in rendezvous missions to ISS where the carrier aircraft can alter its launch point at short notice to extend the launch window available. But for the launch of most commercial payloads this flexibility seems less necessary.

Stratolaunch's flexibility may give it an advantage over a launch vehicle like Antares (even if Antares gets a West Coast launch site), but it's less obvious that it has much advantage over Soyuz. A Soyuz launched from Kourou can reach any inclination from almost equatorial to sun-synchronous.

As far as cost of Stratolaunch compared with the competition is concerned, that's a black area. It's difficult to imagine it being spectacularly cheaper.
Would it save money if the strato launcher / F5 could fly to where the payload is, take on the payload and fuel, and then launch from there?

I'm thinking of something like flying to an airport near Astrium assembly facilities in the UK.

It would need a special runway and I doubt Heathrow would accept disruptions to schedule but something like Boscombe Down (would need another 1,500 feet on the runway).

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28759
  • Minnesota
  • Liked: 8869
  • Likes Given: 5743
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #48 on: 12/24/2011 01:55 pm »

Stratolaunch's advantage is claimed to be in its flexibility to reach "any orbit, any time." This is especially useful in rendezvous missions to ISS where the carrier aircraft can alter its launch point at short notice to extend the launch window available. But for the launch of most commercial payloads this flexibility seems less necessary.

Stratolaunch's flexibility may give it an advantage over a launch vehicle like Antares (even if Antares gets a West Coast launch site), but it's less obvious that it has much advantage over Soyuz. A Soyuz launched from Kourou can reach any inclination from almost equatorial to sun-synchronous.

As far as cost of Stratolaunch compared with the competition is concerned, that's a black area. It's difficult to imagine it being spectacularly cheaper.
Would it save money if the strato launcher / F5 could fly to where the payload is, take on the payload and fuel, and then launch from there?

I'm thinking of something like flying to an airport near Astrium assembly facilities in the UK.

It would need a special runway and I doubt Heathrow would accept disruptions to schedule but something like Boscombe Down (would need another 1,500 feet on the runway).
No, that wouldn't make sense. The more optimum is to have a central, single location for payload integration at some place with a long runway and do all payload integration there. I believe that's what Pegasus does (at Vandenberg).
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline jimoutofthebox

  • Member
  • Posts: 9
  • Liked: 0
  • Likes Given: 0
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #49 on: 01/04/2012 04:32 pm »
There is a significant cost savings to be had from launching a booster from an aircraft.  For example Saturn V used almost 1/3rd of its launch weight in RP and LOX just to get to Mach 1.  I think air launch has the potential to dramatically reduce the cost of putting people in orbit.  Instead of the modified 747s proposed I would use a modified C5 aircraft with the floor removed so that the booster could be carried internally.  With a good redesign the C5 could probably carry 350,000 lbs.   
I would then create a booster based on a scaled up X-37.  The booster would consist of two parts the orbiter section would consist of an airframe with a LOX tank, crew compartment, and a pair of J2 engines as well as a pair of small engines for orbital insertion and reentry.  The orbiter would return for reuse.  The other section would be mounted to the nose of the main assembly and would consist of the LH fuel tank.  The LH fuel tank would also have solid rocket motors that would pull the tank away from the orbiter once the fuel was exhausted.  The tank would then burn up.  The small engines would place the orbiter in orbit just as was done with the shuttle.
There are several advantages to this proposal.  The passengers would not have to enter the orbiter until the aircraft got to altitude so in an emergency the booster could be jettisoned from the aircraft without endangering the passengers.  A lot of money could be saved because all the expensive stuff could be reused.
I estimate that the system outlined above would weigh 350,000 lbs when fully fuelled with a 90% fuel fraction.  It could carry 7 people to orbit or a robot version could carry a payload of 5,000lbs to orbit.

Offline go4mars

  • Senior Member
  • *****
  • Posts: 3754
  • Earth
  • Liked: 152
  • Likes Given: 3184
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #50 on: 01/04/2012 04:46 pm »
The booster would consist of two parts the orbiter section would consist of an airframe with a LOX tank, crew compartment, and a pair of J2 engines as well as a pair of small engines for orbital insertion and reentry.  The orbiter would return for reuse.  The other section would be mounted to the nose of the main assembly and would consist of the LH fuel tank.  The LH fuel tank would also have solid rocket motors that would pull the tank away from the orbiter once the fuel was exhausted.  The tank would then burn up.  The small engines would place the orbiter in orbit just as was done with the shuttle.
Neat idea. 

There are several advantages to this proposal.  The passengers would not have to enter the orbiter until the aircraft got to altitude so in an emergency the booster could be jettisoned from the aircraft without endangering the passengers. 
I think the LAS system with people in dragon would be lower risk to passengers.  If something goes wrong, you don't have to wait for actuators to open the bottom of the aircraft with dragon LAS.

A lot of money could be saved because all the expensive stuff could be reused.
How much would throwing away hydrogen tanks and SRM cost per flight?  Still seems more like a partial re-use solution that can't ever get as cheap as something that throws away only reaction agents.  But I'm no expert. 

I estimate that the system outlined above would weigh 350,000 lbs when fully fuelled with a 90% fuel fraction.  It could carry 7 people to orbit or a robot version could carry a payload of 5,000lbs to orbit.
7 passengers in a winged re-entry vehicle including its rocket engines and oxygen tanks for only 5000 pounds?  Did I read that right?
« Last Edit: 01/04/2012 04:47 pm by go4mars »
Elasmotherium; hurlyburly Doggerlandic Jentilak steeds insouciantly gallop in viridescent taiga, eluding deluginal Burckle's abyssal excavation.

Offline jimoutofthebox

  • Member
  • Posts: 9
  • Liked: 0
  • Likes Given: 0
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #51 on: 01/05/2012 12:09 am »
There are several advantages to this proposal.  The passengers would not have to enter the orbiter until the aircraft got to altitude so in an emergency the booster could be jettisoned from the aircraft without endangering the passengers. 
I think the LAS system with people in dragon would be lower risk to passengers.  If something goes wrong, you don't have to wait for actuators to open the bottom of the aircraft with dragon LAS.

The Dragon would be risky because the passengers would have to be sealed in before take off and I suspect that the aircraft will need a minimum altitude for the escape system to work.

A lot of money could be saved because all the expensive stuff could be reused.
How much would throwing away hydrogen tanks and SRM cost per flight?  Still seems more like a partial re-use solution that can't ever get as cheap as something that throws away only reaction agents.  But I'm no expert.

 A single pressure stabilized tank could be built cheap and small solid rocket motors are also cheap.  I think a completely reusable system would have too high a weight penalty to be cost effective

I estimate that the system outlined above would weigh 350,000 lbs when fully fuelled with a 90% fuel fraction.  It could carry 7 people to orbit or a robot version could carry a payload of 5,000lbs to orbit.
7 passengers in a winged re-entry vehicle including its rocket engines and oxygen tanks for only 5000 pounds?  Did I read that right?
[/quote]

I propose the vehical in orbit would weigh 30,000 lbs including the payload

Offline go4mars

  • Senior Member
  • *****
  • Posts: 3754
  • Earth
  • Liked: 152
  • Likes Given: 3184
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #52 on: 01/05/2012 02:26 am »
I suspect that the aircraft will need a minimum altitude for the escape system to work.
why would it need minimum altitude to work?  Seems to me it could work while taxiing around the airport. Couldn't do that with yours until it is airborn.
Elasmotherium; hurlyburly Doggerlandic Jentilak steeds insouciantly gallop in viridescent taiga, eluding deluginal Burckle's abyssal excavation.

Offline Zed_Noir

  • Senior Member
  • *****
  • Posts: 2643
  • Canada
  • Liked: 430
  • Likes Given: 649
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #53 on: 01/05/2012 03:46 am »
I suspect that the aircraft will need a minimum altitude for the escape system to work.
why would it need minimum altitude to work?  Seems to me it could work while taxiing around the airport. Couldn't do that with yours until it is airborn.

IIRC both the F/FB111 & the B1A bombers have crew escape capsules capable of zerp-zero (zero altitude & zero speed) egress. So, don't think a Dragon capsule with throttle-able LAS should have any problems getting away from the carrier aircraft at any altitude.

Offline cuddihy

  • Full Member
  • ****
  • Posts: 899
  • Liked: 189
  • Likes Given: 221
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #54 on: 01/05/2012 05:00 am »
The stratolaunch idea, in combination with cross feed for F9H, makes me wonder about an alternate idea for Stratolaunch to turn the Lifter from a "0.5" stage to a "0.75" stage -- what about using a boost from one of the F5 engines as a JATO to allow smaller wings, and then additionally to boost speed and altitude for pitchup and release-- meanwhile  crossfeeding from the A/C-- either just Fuel or both-- to increase payload?

This would allow some 'envelope expansion' for the lifter over time as well.

Any thoughts?

Offline jimoutofthebox

  • Member
  • Posts: 9
  • Liked: 0
  • Likes Given: 0
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #55 on: 01/06/2012 04:37 pm »
I suspect that the aircraft will need a minimum altitude for the escape system to work.
why would it need minimum altitude to work?  Seems to me it could work while taxiing around the airport. Couldn't do that with yours until it is airborn.

IIRC both the F/FB111 & the B1A bombers have crew escape capsules capable of zerp-zero (zero altitude & zero speed) egress. So, don't think a Dragon capsule with throttle-able LAS should have any problems getting away from the carrier aircraft at any altitude.

Both of the aircraft systems you refer to fire straight up.  When the air launched dragon is on the ground it is pointed forward.  In order to escape on the ground the LAS system would have to double the size of the system compared to the vertical LAS system since you can only use the thrusters pointed down.  Also you wont have a lot of time from when the explosive bolts fire and the Dragon falls to runway.  I don't believe safety was well thought out for this system.  Thats why I proposed a system that would leave the passengers in the mother aircraft until a safe altitude was reached.

Offline RanulfC

  • Senior Member
  • *****
  • Posts: 4446
  • Heus tu Omnis! Vigilate Hoc!
  • Liked: 814
  • Likes Given: 32
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #56 on: 01/10/2012 03:31 pm »
The stratolaunch idea, in combination with cross feed for F9H, makes me wonder about an alternate idea for Stratolaunch to turn the Lifter from a "0.5" stage to a "0.75" stage -- what about using a boost from one of the F5 engines as a JATO to allow smaller wings, and then additionally to boost speed and altitude for pitchup and release-- meanwhile  crossfeeding from the A/C-- either just Fuel or both-- to increase payload?

This would allow some 'envelope expansion' for the lifter over time as well.

Any thoughts?
I suspect that's the only way they are going to reach the AoA shown for the carrier aircraft in the first place so IMHO that's already a "given" feature.

As a JATO you're going to have issues with runway impingement of the exhaust plume which COULD be an issue unless a special surface is used. On wing size, the wings are sized for maximum altitude so reducing the wing-span means the carrier aircraft won't reach as high an altitude with the given payload mass.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

  • Senior Member
  • *****
  • Posts: 4446
  • Heus tu Omnis! Vigilate Hoc!
  • Liked: 814
  • Likes Given: 32
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #57 on: 01/10/2012 03:44 pm »
Both of the aircraft systems you refer to fire straight up.  When the air launched dragon is on the ground it is pointed forward.  In order to escape on the ground the LAS system would have to double the size of the system compared to the vertical LAS system since you can only use the thrusters pointed down.  Also you wont have a lot of time from when the explosive bolts fire and the Dragon falls to runway.  I don't believe safety was well thought out for this system.  Thats why I proposed a system that would leave the passengers in the mother aircraft until a safe altitude was reached.
Just as an FYI, "zero-zero" escape systems are specifically designed to get the crew to a minimum altitude where a parachute can function to slow their ground impact. This means (in the cited cases of the F-111, and B-1B) that they have control systems which function to ensure that the crew is headed UP and AWAY from the ground even if the aircraft in question is upside down and only a few feet from the runway.

In the case of a Dragon-ish LAS on an Air-Launched rocket the Dragon on-board flight computer would use ALL the rockets with those towards the bottom at a higher thrust pushing the vehicle FORWARD and UP to clear the scene. The rockets would fire at the same TIME as the explosive bolts, (though I think on Dragon it is a spring system rather than explosives??) so the drop would be minimul.

Something I need to ask: You state that you would "modify" a C-5 by removing the floor, and later mention a mechanism to "open" the bottom. First I need to point out that while the main "frame" of the C-5 is hung from the wing unlike most commercial aircraft the "floor" is an integral part of the airframe as well having the ties that support the wheel assemblies included within the structure. (Note also that maximum payload mass is determined by the wing-carry structure not the cargo flooring)

How exactly are you planning on releasing the Launch Vehicle in flight in the first place?

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline jimoutofthebox

  • Member
  • Posts: 9
  • Liked: 0
  • Likes Given: 0
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #58 on: 01/10/2012 05:00 pm »
I don't believe safety was well thought out for this system.  Thats why I proposed a system that would leave the passengers in the mother aircraft until a safe altitude was reached.
Just as an FYI, "zero-zero" escape systems are specifically designed to get the crew to a minimum altitude where a parachute can function to slow their ground impact. This means (in the cited cases of the F-111, and B-1B) that they have control systems which function to ensure that the crew is headed UP and AWAY from the ground even if the aircraft in question is upside down and only a few feet from the runway.

In the case of a Dragon-ish LAS on an Air-Launched rocket the Dragon on-board flight computer would use ALL the rockets with those towards the bottom at a higher thrust pushing the vehicle FORWARD and UP to clear the scene. The rockets would fire at the same TIME as the explosive bolts, (though I think on Dragon it is a spring system rather than explosives??) so the drop would be minimul.

Something I need to ask: You state that you would "modify" a C-5 by removing the floor, and later mention a mechanism to "open" the bottom. First I need to point out that while the main "frame" of the C-5 is hung from the wing unlike most commercial aircraft the "floor" is an integral part of the airframe as well having the ties that support the wheel assemblies included within the structure. (Note also that maximum payload mass is determined by the wing-carry structure not the cargo flooring)

How exactly are you planning on releasing the Launch Vehicle in flight in the first place?

Randy

Letís do the math.  You have 12,000 lb object 15 ft from the runway.  It has to generate 12,000 lbs of thrust directed at the ground just to hover.  You need to do more than hover so letís say you need 24,000 lbs of thrust to accelerate away at a reasonable speed. The thrusters are fixed at 30 deg to the runway so the resultant vertical thrust vector is Ĺ of the available thrust so now youíre up to a total of 48,000 lbs of thrust.  This results in a need big fuel gulping engine.
 
You canít argue with basic physics

As far as the question on the C5.  If you remove weight from an airframe you increase the useful load because you donít have to lift the missing structure.  I suspect there is a lot of weight in the vehicle deck and ramp that doesnít add the strength of the airframe especially if the load is suspended from the center section of the wing.  The load from the wings to the landing gear is carried by the sides of the fuselage not the deck.  I would not change structure on the sides. If aerodynamics required doors on the bottom of the aircraft they would weigh a fraction of the original structure because they wouldnít  carry any load.

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32550
  • Cape Canaveral Spaceport
  • Liked: 11343
  • Likes Given: 334
Re: Impact of Stratolaunch on F9 demand 5-10 years from now
« Reply #59 on: 01/10/2012 05:52 pm »
The load from the wings to the landing gear is carried by the sides of the fuselage not the deck. 


Load from the wing is meaningless WRT removal of the floor.  The landing gear puts loads into the floor.  The load bearing capability of the fuselage is from is shape of its structure. That is why during ground crashes vehicle breaks apart at fuselage joints.

Tags: