Rocketplane Global (Back again)

[RanulfC]

Didn't see this and search only shows an old topi but Rocketplane Global "re-launched" in April:
http://www.rocketplaneglobal.com/

Randy

[UltraViolet9]

Mitch Clapp wanted to take another run at his Blackhorse concept after ALASA was terminated?

[Steven Pietrobon]

They have two planes. Rocketplane XP for suborbital tourist flights to 100 km and the larger Rocketetplane XS for carrying 1500 kg payloads to LEO.

XP takes off on jets and then uses a 160 kN RP-1/LOX rocket engine to reach apogee.

XS takes off with the propellant tanks empty (except for the kerosene used by its jet engines) and fills up with RP-1 and LOX from a separate tanker aircraft. Fires the rocket engine, deploys the upper stage and payload and then re-enters.

[FutureSpaceTourist]

If the main picture on the website is reasonably accurate, here are the relative sizes.

[savuporo]

I believe these are done in mspaint, and i think i saw something similar on a rocketplane website sometime in 1999 or thereabouts

What next, geocities comeback ?

[Rocket Science]

I always liked the XP concept. I wish them good luck with her and the XS with this go at it again!

[TrevorMonty]

There doesn't seem to be any lack of novel ideas for delivery payloads to space.

The refuelling in flight means plane can be significantly smaller and cheaper.

[gin455res]

I want to see this implemented but bigger with a stratolauncher tanker.

[Machdiamond]

I believe these are done in mspaint, and i think i saw something similar on a rocketplane website sometime in 1999 or thereabouts

What next, geocities comeback ?

Unsurprisingly the source code reveals that today's web site has been created with Adobe GoLive 4 released in... 1999.

[CameronD]

There doesn't seem to be any lack of novel ideas for delivery payloads to space.

The refuelling in flight means plane can be significantly smaller and cheaper.

The refuelling in flight sounds extraordinarily dangerous.

With no details of fuelling probes or similar it isn't clear exactly how they propose to do this.  RP-1 might be no big deal using standard systems, but has anyone ever tried in-flight transfer of cryogenic liquids?

[Lars-J]

There doesn't seem to be any lack of novel ideas for delivery payloads to space.

The refuelling in flight means plane can be significantly smaller and cheaper.

Not really... They would be refueling pretty low in the atmosphere. What you save is a bit of wing mass since you don't have to take off as heavy, but you add mass for propellant transfer and a lot of potential failure modes.

I just don't get how enamored people are of piloted aircraft to LEO. Want to carry passengers? Fine... But why in the world is this (the larger XS) piloted?

[gin455res]

I want to see this implemented but bigger with a stratolauncher tanker.

However, maybe the cubed square law might not make this sensible.

Alternately, I wonder if we had electric fans instead of jets and the tanker supplied power to recharge the battery packs and keep the vehicle flying during the refuel; could the same recharged battery packs then run the pumps for the rocket engine. Maybe even share the electric motors between the fans and the pumps?

[CameronD]

Not really... They would be refueling pretty low in the atmosphere. What you save is a bit of wing mass since you don't have to take off as heavy, but you add mass for propellant transfer and a lot of potential failure modes.

I just don't get how enamored people are of piloted aircraft to LEO. Want to carry passengers? Fine... But why in the world is this (the larger XS) piloted?

Because, if you (a) allow the wing mass to reduce to optimal for spaceflight and (b) remove the pilot... then you're left with a rocketplane that looks, and operates, just like everyone else's! 

[RanulfC]

Not really... They would be refueling pretty low in the atmosphere. What you save is a bit of wing mass since you don't have to take off as heavy, but you add mass for propellant transfer and a lot of potential failure modes.

I just don't get how enamored people are of piloted aircraft to LEO. Want to carry passengers? Fine... But why in the world is this (the larger XS) piloted?

Because, if you (a) allow the wing mass to reduce to optimal for spaceflight and (b) remove the pilot... then you're left with a rocketplane that looks, and operates, just like everyone else's! 

Being honest "aircraft-like" operation tends to get one picturing.. Well, an aircraft. Which leads to needing a pilot and so on...

You'll note that despite it being rather more logical "drone/remote/automated" aircraft are still a minority for the applications where you'd logically expect them to be used. Despite the "pilot" (sorry, need to stop here for a second and just say that I have to use stupid words to get my point across. I know that means I must have a weak argument, but that's why I use bad words). (fighter/bomber/airline, you name it somebody thinks they have WAY more power than the do ) conspiracy ideas we're not quite at the point where "people" really trust automation. (Or a "remote" pilot, why did HE stay on the ground? What's he know I don't??. Etc)

As for the aerial propellant transfer, no we've not tried it in practice but it looks about as hard/easy as non-cryo transfer. (Note the "looks" part there ) What you gain is lighter landing gear, somewhat of an airframe and somewhat smaller wings. As all this, (in theory) tends towards lower empty weight and hence lower cost, (serious metric BTW M/T weight to Cost is an actual formula used commercially) it is a 'viable' argument.

Much like StratoLaunch I remain interested but not convinced.

Then again my partially completed "pet" project uses the original Blackhorse as a baseline so I may be a bit biased

Randy

[john smith 19]

I just don't get how enamored people are of piloted aircraft to LEO. Want to carry passengers? Fine... But why in the world is this (the larger XS) piloted?

There are probably various reasons for the general prejudice but in this specific system it might be simple TRL.

True the X17 demonstrated drone (or at least remotely assisted) landing  in the 1950s, but IIRC actual in flight refueling is still cutting edge, so a human in the loop probably looks the best (simple) way to do it.

For now IFR remains one of those things that still separate nearly all drones from military aircraft, which might explain why air forces seem quite reluctant to roll it out.

The refuelling in flight sounds extraordinarily dangerous.

With no details of fuelling probes or similar it isn't clear exactly how they propose to do this.  RP-1 might be no big deal using standard systems, but has anyone ever tried in-flight transfer of cryogenic liquids?

Not really. In flight refueling has been a relatively common practice amongst the worlds air forces since the 50's.

What's never been SOP is dual refueling, one of which is a cryogenic. that's going to need a dedicated aircraft, with all its attendant operating costs, unless they can devise a removable IFR package (generically a "buddy pack" and fitted to aircraft of the same type) so they only need to rent an aircraft of a certain type on demand to fly.

In principal building such a package to be carried by a transport aircraft is simpler than dropping an ELV out of one in flight, but still a demanding piece of engineering. 

It's interesting to note that historically RP bought Kistler, a company (in theory) in a much stronger financial position than they were.

The fact they have returned to the business suggests they are quite good on the "business" side of the problem IE getting investors interested and convincing them they have both a viable business plan and a team that can execute it.

Conceptually I'd say RP's idea is closest to Reaction Engines concept.

Both use an outside agent (in flight refueling or air breathing) to allow you to leverage the enormous investment in HTOL aircraft technology over more than a century while allowing you to build a vehicle needing a high performance aircraft mass fraction, rather than a rocket mass fraction.

That said a Rocketplane Global replacing all its engines with something close to the 40 000lb testbed engine REL are working on is a non starter. The shift in fuels and ConOps is just too big for RPG (?) to accept. 

[john smith 19]

With no details of fuelling probes or similar it isn't clear exactly how they propose to do this.  RP-1 might be no big deal using standard systems, but has anyone ever tried in-flight transfer of cryogenic liquids?

Yes, AFAIK no one has ever tried this, ever.

Like the REL pre-cooler it is the unique component of the concept. AFAIK no one has ever tried to make a coupling (either Boom or Probe/Drogue) with LOX in the pipe, then release the coupling afterward.

True the outside air temperature is cold, but LOX is about 2.5x colder than the freezing points of most jet fuels. It is also an oxidizer. Testing a coupling set (boom or P/D) and finding either no issues, or issues to fix, would go a long way to reassuring backers and raising TRL levels

Best case. No issues.
Worst case, multiple replacement parts, not just of parts expected to wear out, but also core components of the coupling which are just not compatible with LO2, either because of the temperature, or its reactivity. Testing this, with say 2 carts holding each half of the coupling in a hangar is going to be a lot cheaper than trying this out with two aircraft at 40 000ft.

Getting this done ASAP would do a lot to raising the level of confidence in the concept, given it's the really unique element of the architecture (although converting a biz jet into a true aerospace plane will not be trivial either.)

[abaddon]

Hm, probably a dumb idea, but maybe you could instead take off with the full load of LOX, so when you reach altitude you just top off the RP-1 and go, without having to worry about the LOX.

You of course have boil-off so probably a limited window to get to altitude and tank.  But maybe if you spec the LOX tank to hold a bit more than required it works out in the end.  No idea how heavy the LOX would be and if this saves enough to make it worthwhile.

Feel free to shoot this down, just bored and musing... the whole idea seems like a mistake to me anyway.

[john smith 19]

Hm, probably a dumb idea, but maybe you could instead take off with the full load of LOX, so when you reach altitude you just top off the RP-1 and go, without having to worry about the LOX.

You of course have boil-off so probably a limited window to get to altitude and tank.  But maybe if you spec the LOX tank to hold a bit more than required it works out in the end.  No idea how heavy the LOX would be and if this saves enough to make it worthwhile.

Feel free to shoot this down, just bored and musing... the whole idea seems like a mistake to me anyway.

LOX is about 50% denser than aviation fuel. It'll also increase the weight on the landing gear, which is significant.

BTW the simplest way to convert a biz jet to this configuration would be to find a 3 engine design and strip the middle one and replace it with a rocket engine, probably after upgrading the remaining engines to carry the load during take off and flight to refueling altitude.

Unfortunately only Dassult seems to make 3 engine biz jets anymore.

[Steven Pietrobon]

Hm, probably a dumb idea, but maybe you could instead take off with the full load of LOX, so when you reach altitude you just top off the RP-1 and go, without having to worry about the LOX.

Kerolox has a mixture ratio ranging from about 2.3 to 2.7 to one. That means that LOX is about 70% to 73% of your total propellant mass. So only loading RP-1 at altitude means you have to carry 70% of to 73% of your total propellant mass, so it means not much of advantage compared to loading LOX at altitude. An alternative to LOX is HTP (high test peroxide) which is storable at room temperature and non-toxic, but nearly everyone in the US is afraid of the peroxide boogeyman. HTP has a mixture ratio about 7 to one part RP-1, meaning it is about 88% of total propellant mass. You could carry the flight RP-1 in your spaceplane and only transfer the HTP at altitude, avoiding having to transfer two propellants in close proximity to each other (or in separate booms).

[FinalFrontier]

Left asking myself the same thing as in the past with this concept. Why do we need this and who would need it?

I don't quite see the purpose or funding stream for development of this. Same as before and the time before that and so forth.