Fast sketch of a two stage orbiter

[scottb50]

I have a little bit different idea. A Modular propellant tank, LH/LOX with a single SSME mounted to it. Put four together, add a couple of solid boosters, in two of the same basic Modules, and put it all into a non-structural aerodynamic shell with a restartable upper stage mounted to the side.<br /><br />Drop off the upper stage at 80 miles and return the first stage for re-fueling and relaunch.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

A "non structural aerodynamic shell"??? Any shell is going to need structure if you put a load on it at mach 5-10. Please elaborate.

 

[scottb50]

By non-structural I mean the loads are carried by the inner Modules, the outer shell would be a light weight fairing. Think of a fabric covered airplane, the load is carried by the framework, not the fabric. Enough stiffness would be needed to maintain an aero-dynamic shape, but could be kept minimal.<br /><br />The idea is the six Modules are solidly connected to one another and any structure needed to support and keep the shape of the shell attaches to the Modules. Because the launch stage returns from 80 miles or so the heating of the structure would be considerably less than a full re-entry, like the SS-1 which required minimal temperature protection materials. <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

Yes, though SS1 peaked out at mach 3.5, right at the edge of the thermal thicket. As soon as you get to hypersonic velocities you are dealing with more exotic stuff, depending on how fast it is going in what density atmosphere. You could theoretically build a Rogallo wing of steel wire fabric and reenter from orbit at a -1 deg angle, given sufficiently minimal load. GE test such a system in a real reentry in the early 70's. The point is to loose as much velocity in as thin an atmosphere as possible.<br />

 

[scottb50]

One way to reduce velocity is a larger structure, a vehicle similar to Venture Star, creates more drag because of its size and spreads the thermal load over a larger area. Obviously you would need some TPS, but with half the initial speed of Shuttle the amount would be minimal. <div class="Discussion_UserSignature"> </div>

 

[annodomini2]

Wouldn't it be better for it to have swept wings, as if it is feasable have the 1st stage deploy the 2nd stage at a supersonic speed?<br /><br />Additional thought, using something like a LACE engine, this could produce liquid oxygen for the second stage in flight. Possibly a safety benefit as the 2nd stage is not carrying oxidiser during take off. Plus theoretically LACE engine can operate at higher altitudes and higher velocities than conventional jet engines. Making leo velocity more feasable.<br /><br />Mid flight refuelling could theoretically allow lower take off weight (assuming it used normal jet fuel), this could also theoretically cut costs as infrastructure for supplying fuel in mid air already exists (i.e. no new tech required).<br /><br />Some ideas, comments appreciated.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[larrison]

Keep in mind this is supposed to be a cheap lightweight crew transport vehicle. The first stage is subsonic and total weight should be less than 400 ton's (the airbus weighs 450 metric tons) and will have a payload (people) of less than 3,000 lbs. I have considered putting SRB'S or hybred rockets in the back of the first stage and burning them at an altitude of 50,000 feet (10 mi) then have first and second stage seperation at 60,feet.

 

[mlorrey]

I am curious as to why people feel they have to build a whole new system from scratch? If your design is 400 tons, and an Airbus is 450 tons, why not buy an Airbus? <br /><br />Pegasus already proved the idea by being airlaunched from a Lockheed L-1011, so why spend billions on developing a whole new transport class aircraft? Its a total waste of resources. <br /><br />Plan on buying an Antonov, or a C-5, or a C-141 (the 141s are getting retired, btw, so you ought to be able to purchase them through the boneyard through the same program that put so man C-130's in private hands.) You are reinventing the wheel, and a vaporware wheel at that. <br /><br />BTW: there is a limit to the mass of vehicles carried external to any aircraft. The trade study used to support the tether drop that SpaceDev did talks a bit about the external payload limits of different large aircraft.

 

[larrison]

I'm not suggesting using an airbus. I'm just trying to point out that the weight is not an obstacle to a runway launch.<br />I believe were already using systems that if the properties of those systems were combined (not the systems themselves) cheap flights to orbit could be attainable not within fifteen to twenty years but two or three. <br />And we do need to reinvent the wheel (or at least improve it greatly) NASA wants to spend 104 billion dollars to go to the moon. I've seen how quickley those numbers can climb. I've also seen waste and miss management first hand and how the best way isn't always chosen for reasons that fail to make any sense.<br /><br />The people who will make space travel common will those who are uncommon and can see whats works best not what has been done before or is accepted as the standard.

 

[mlorrey]

I am suggesting you use an Airbus. Insisting on reinventing the subsonic transport 'wheel' is simply asking to have your project shot down due to excessive capital requirements, to build a whole new subsonic transport aircraft. That plane alone is going to cost tens of billions to develop.<br /><br />Refusal of some to accept this sort of thinking is probably one reason why Dobbins acts like such a curmudgeon here: there is a lack of rational acceptance or understanding of economics here.<br /><br />NASA is spending 104 billion on lots of makework for the 10,000 man standing army of welfare engineers at Kennedy, while developing spacecraft that kinda look like the Apollo just to get support from people who think that is the safe bet, but in reality are all new vehicles with unknown risks.<br /><br />The smart thing NASA is doing is basing what they are doing on as much existing technology as they can get away with (SRB, SSME, etc) while still stoking the congressional constituency jobs fire.<br /><br />Sometimes what was done before was best, and simply needs to be applied in a new way.<br /><br />I can name, offhand, a half dozen models of supersonic aircraft in the boneyard in Arizona which, when reskinned with carbon-carbon and titanium and reequipped with RBCC engines, along with a few other minor mods, would make perfectly acceptable RLVs and would save billions simply because their aerodynamics and structures are so well known, they are proven rugged. Launch any of them off the dorsal side of an Airbus, 747, or Antonov 224, and avoid LH2 fuel like the plague, and you will have an orbital vehicle. <br /><br />Offhand: F-92, F-102, F-106, B-58, B-70, SR-71, F-16XL are all aircraft that would provide suborbital, if not orbital capability with re-engining and incorporation of high temp materials, along with airlaunch and/or air-refuel

 

[annodomini2]

<blockquote><font class="small">In reply to:</font><hr /><p> I am suggesting you use an Airbus. Insisting on reinventing the subsonic transport 'wheel' is simply asking to have your project shot down due to excessive capital requirements, to build a whole new subsonic transport aircraft. That plane alone is going to cost tens of billions to develop.<p><hr /></p></p></blockquote><br /><br />I understand where you are coming from and your argument is valid 'why reinvent the wheel?'.<br /><br />But as Burt Rutan has proved it doesn't cost billions of dollars!<br /><br />An existing aircraft 'may'(!) provide a cheaper alternative to sub-orbit/orbit, but it may not be the ideal solution, the costs may go up exponentially as any modifications that are required may end up costing more than starting from scratch with a dedicated aircraft.<br /><br />One of the reasons why I mentioned a supersonic deployment of the orbital vehicle. A mach 2-3 launch at high altitude could significantly reduce the size and weight of the second stage.<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>NASA is spending 104 billion on lots of makework for the 10,000 man standing army of welfare engineers at Kennedy, while developing spacecraft that kinda look like the Apollo just to get support from people who think that is the safe bet, but in reality are all new vehicles with unknown risks. <br /><br />The smart thing NASA is doing is basing what they are doing on as much existing technology as they can get away with (SRB, SSME, etc) while still stoking the congressional constituency jobs fire. <br /><br />Sometimes what was done before was best, and simply needs to be applied in a new way.....<br /><br />I can name, offhand, a half dozen models of supersonic aircraft in the boneyard in Arizona which, when reskinned with carbon-carbon and titanium and reequipped with RBCC engines, along with a few other minor mods, would make perfectly acceptable RLVs and would save billions simply because their aerodyn</p></blockquote> <div class="Discussion_UserSignature"> </div>

 

[rocketman5000]

Almost all of the models that mlorrey listed ended up in the boneyards as a result of rapid technological advances of the cold war. The machines were simply outclassed and needed to be replaced as front line fighting machines

 

[scottb50]

Since it's a fairly late model aircraft lets look at the F-16: Empty weight 18,000 pounds. Add TPS for re-entry, remove the standard engine and replace it with a rocket and a good guess would be about 25,000 pounds.<br /><br />I think it would be safe to say you couldn't cram anywhere enough propellant into an F-16 to even start an engine, let alone boost the vehicle from 8-100 miles and M.7 to M25. So now we have to look at add-on tanks and even more mass the carrier aircraft has to take to altitude. You would have to take a Delta 5, which weighs 511,000 pounds to altitude to orbit an F-16.<br /><br />In other words it seem like a futile attempt that even if it worked would only get 1 0r 2 people to orbit to begin with. <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

Try these numbers:<br /><br />F-106 airframe.<br />Skin replaced with Titanium and C-C/Si-C<br />J75 engine removed (though it would be interesting to test it with the MIPCC that DARPA's RASCAL program promoted). That saves 5700 lb off the 23,000 lb dry weight.<br />Mount composite LOX tank in place of the engine: 24,000 lb of LOX.<br />Seal up the intakes and make them into fuel tanks. With the normal fuselage fuel tank, and a fuel tank in the belly missile bay, you have 30,000 lb of fuel. The kerosene used is RP-1 with boron additive. Isp of 457.<br />Use the wing tanks for H202 (peroxide). 5,000 lb. Used for active cooling and MIPCC injection into the ramjet.<br /><br />Engines:<br />a) underbelly ramjet, 40,000 lb thrust, used from 450 kt up to mach 6-7<br />b) SpaceX Merlin engine, 80,000 lb thrust, used at takeoff and from mach 5 on up.<br /><br />As the Falcon1 uses plain RP-1, not boronated RP-1, this vehicle should achieve a much better Isp on the Merlin, and a way better average Isp thanks to the ramjet, which should achieve at least 2000-2500 secs burning the boronated RP-1.

 

[scottb50]

There's so much junk hanging out there I would hate to see a re-entry. Why the canards? That air scoop is going to take a beating on re-entry as will the wigtip extensions. I also think you are seriously underestimating the amount of propellant required. <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

Well, the upper stage on the center fin stub detaches to put a larger payload in orbit, and may not be needed depending on the final velocity of the launcher.<br /><br />The drop tanks, obviously, get dropped, and may not be needed. I've only calculated fuel mass for all tanks except the drop tanks (and the drop tanks on the 106 are hypersonic rated, btw).<br /><br />The fuel is greater than that carried by the first stage of the Falcon1 (not even counting all the air that it doesn't need to carry that gets used as oxidizer), and has an Isp 100-140 secs higher than the Merlin burning plain RP-1. Figuring in the Isp boosts from the boron additive, and the airbreathing phase, I think you are misunderestimating what it is actually capable of.<br /><br />The ramscoop will also be cooled on reentry with peroxide. The canards and the wingtip feathers are to reenter controllably at a very high angle of attack, to decelerate in the upper atmosphere with a much higher aerodynamic cross section than, say, the shuttle does. <br /><br />The canards, winglets, leading edges, nose cone, and underbelly are all carbon-carbon, with the upper surface titanium. So, no, there isn't 'so much junk' hanging out there.

 

[scottb50]

So, no, there isn't 'so much junk' hanging out there.<br /><br />Ist how do you consider the canards and drop tanks hypersonic rated? <br /><br />Falcon1 puts about 570kg into LEO the F-106 weighsabout 12,500kg empty. Add your upper stage, canards, those wingtips ect., and it gets a lot heavier.<br /><br /> <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

The original F-106 drop tanks were hypersonic rated, and were planned to be kept for the F-106X mach 5 interceptor that competed against the YF-12 in the early 60's ADC competition. The 106X had much larger canards than what I've envisioned, along with some rather huge F-15 style intakes.<br /><br />The F-106 is 23,000 lb empty. That includes 5,700 of jet engine, which will be removed. It also includes lots of weapons handling, radar, and weapons control systems avionics, about 750 lb worth. Stripping out the intake surfaces is some more weight. Then replacing air skin steel and aluminum with carbon-carbon will shave panel weight down 20-30%. Wingtips are cut off and replaced with carbon-carbon, which is also lighter than the steel and aluminum of the existing structures. Leading edge will be replaced by C-C. All hydraulics pumps, lines, and pistons will be replaced with electric actuators. 3/4 of the center vertical stab will be cut off. In the end, empty weight should be about 16,000 lb.<br /><br />Upper stage mass will be about 2600 lbs.<br /><br />Falcon1 weighs 70,000 lbs wet with a mass fraction of about .9 and an Isp of under 300.<br /><br />The X-106 will weigh about 78,000 wet, loaded with the upper stage, with a mass fraction of about .77-.80 and an average Isp at least double that of the Falcon1.

 

[scottb50]

Seems like it would be just about as easy to build a whole new design.<br /><br />The structure of the Falcon is considerably less than that of an F-106, it will support it's own weight, unlike other boosters, but it is not overly robust, plus the second stage lifts itself and a rather small payload into orbit.<br /><br />Luckily the F-106X mach 5 interceptor never flew. <div class="Discussion_UserSignature"> </div>

 

[mlorrey]

No, it wouldn't. If you had a couple hundred million, maybe. You can buy surplus F-106's, delivered, for about $24,000.00 today, the few that are left. This is an aircraft that cost about $4 million new and had a hundred million invested in its development, back when that was real money (try about ten times those numbers today for the same plane).<br /><br />The largest problem today with RLV projects is the capital cost. Here we have an airframe you can buy and modernize for a whole lot less than designing, testing, redesigning and retesting a whole new aircraft. The cost of doing that, and the 'standing army' of engineers and machinists would be prohibitive.<br /><br />My concept, with the exception of the cost of the Merlin engine, could be built for not much more than the cost of the EZ-Rocket.<br /><br />Sure the structure of the Falcon1 is less than half that of this one, and while it will support its own weight, it is not yet proven to be a rugged design, and its reusability has yet to be tested. The RASCAL program projected a minimum of 50 flights from a project like mine, per aircraft. Reusability is about engineering in margin for long term structural fatigue. As the Falcon1 has the highest mass fraction of any launcher, I doubt it has a lot of structural margin. It will likely never fly more than ten flights per launcher, if that.<br /><br />Most F-106's were retired with between 5000 and 6000 hours on them. Their airframes are certified for 8000 hours. Even if you figured the stresses of this program as making one launch flight hour equal to 10 hours of normal supersonic/subsonic combat use, most airframes would still have over 200 launches in them.<br /><br />Keep in mind the Falcon1, burning normal kerosene, has an average Isp of under 300 secs. The X-106 will have an Isp on its Merlin-class engine of 400-457 seconds, burning boronated kerosene, and the ramjet will get between 1500-2500 secs. Average Isp of the X-106 will be twice that of the Falcon1, at a bare

 

[scottb50]

I've been kind of hesitating addressing the Boron additive also. I seems to remember reading somewhere it was not a very friendly source of power. Merlin is rated at 304S ISP in vacuum, will Boron raise it that much? That's almost up there with LH/LOX engines.<br /><br />I have a much simpler idea anyway. A current production business jet with the entry door replaced by a docking adapter. Put a launch fairing over it and launch it on a Delta. For return you have a descent vehicle based in orbit. The vehicle takes the jet through the high heating are and drops it off at 200.000 feet before powering back to orbit for re-use. Cargo uses simpler Modules parachuted to a delivery center. <div class="Discussion_UserSignature"> </div>

 

[josh_simonson]

A momentum exchange transfer tether could catch suborbital spaceplanes, and also decelerate them such that they require little to no TPS on the return trip.

 

[mlorrey]

Yes, Josh, a tether is an excellent idea. I particularly like building a geosynch tether that ends at a stationary space station in LEO, about 300 miles up. Suborbitals could launch straight up to it, peak out and land on the bottom platform, and drop its passengers and/or cargo to ride the elevator the rest of the way.<br /><br />Having a GEO tether end just above a corridor of LEOs would eliminate the risks of collisions damaging the tether, or the tether damaging satellites (or the ISS). This would also ease the engineering requirements on the tether itself a bit...<br /><br />As for boronated kerosene, there are issues with it with coking and erosion of the nozzle, but given that the Merlin engine has an ablative nozzle that is replaced after every flight, this becomes a non-issue. It really does provide a huge boost in Isp comparable to LH2, much as aluminum helps solid fuels significantly. <br /><br />Burning boron produces a LOT of smoke, apparently. A lot of boron oxide particulates precipitate out of the exhaust plume. This just bauxite, though, and while it may be an issue if it were settling over a populated area, at least aesthetically, launching over ocean it will settle to the bottom as a normal component of sedimentation. It is non-toxic.

 

[larrison]

Geosynchronous orbit is 22,241 miles up. A tether to reach down to 40 miles is still in the science fiction stages. Raising the tether to a higher altitude doesn't increase it's feasibility and going higher with a ship defeats the porpose of the tether.

 

[larrison]

If a ship is designed to go into orbit it must do one of two thing carry a crew of at least eight people ( were trying to go forward with our technology not backwards) or a paylode. Both should weigh between 2.5 to 3 tons. Using existing flight vehicles would cost too much to convert and wouldn't satisfy the goal of putting up the required weight.<br />The vehicle must preform several functions.<br />Fly through the atmosphere.<br />Reach orbital velocity.<br />Survive the enviroment of space (and keep it's crew and passengers alive).<br />Deorbit an decelerate.<br />Fly back through the atmosphere.<br />Land.<br />It would be nice to have a vehicle designed to operate in each of these stages as if it were the only thing it was designed for but that is unreasonable. However I believe the first flight throught the atmosphere can be seperated from the rest. The first vehicle is like detachable wings. It's purpose is to create lift. Once it's no longer is useful all of its weight is disguarded (wings, engines and fuel). It may be possible to use hybred rockets to move from 50,000 feet to 60,000 feet. At this point the second stage would seperate pointing straight up. It's job now is to fly to an 80 mile altitude and reach 17,500 miles per hour. If it burns only 70-80% of it's fuel the rest could be used for a deorbit burn. It could slow down to mach 12 or so (from mach 25). Deceleration would ne easier since there is less mass to slow down. A partially inflatable parachute (made from heat cloth) could be stored in the back and expand to create a surface area several times that of the ship.