X-15 Redux

[Broncazonk]

I'm a real fan of the X-15 and the X-15 program. Problem: They didn't go high enough: max altitude was about 60-miles with external tanks. Let's design the X-15 Mark II and then park that thing in a stable 120-mile orbit.

What will it take to accomplish this?

My idea would be to use an air-augmented rocket motor similar to the Russian Gnom instead of a XLR-99 set-up, with a double solid-rocket booster assist, and we drop it at 40,000 feet from a heavy lift jet. (It would look like a bigger, sexier X-15 with two SRB's bolted on, like the Shuttle, but without the external fuel tank.)

http://astronautix.com/lvs/gnom.htm

http://en.wikipedia.org/wiki/Air-augmented_rocket


At only 50-feet long, the X-15 was able to go halfway, surely we can make this happen.

Bronc

PS: Please be kind. I'm not an engineer.

 

[Orionblamblam]

At only 50-feet long, the X-15 was able to go halfway,

Actaully, no. It was able to get to about Mach 6, about 1/4 orbital velocity. Which means an orbital X-15 would need to go 4 times faster... requiring 16 times the propulsive energy.

And a hint: if you are hauling your updated X-15 to altitude under a B-52 or similar aircraft, using an airbreathign engine on the X-15 would be spectacularly unwise if your goal is orbit. You are already above most of the atmosphere when you start it up.

 

[The Artist]

Getting to orbit is a problem but so is getting back from orbit. That well known picture of an X-15 model atop a booster assembly made me laugh. I'm not an engineer either but I'm fairly sure that an entry from orbit generates more heat than that generated by Mach 6 flight. Look at the structure and thermal protection on DynaSoar and compare that to the X-15. That will give you an idea of what you'd have to do to the X-15.

 

[Byeman]

At only 50-feet long, the X-15 was able to go halfway, surely we can make this happen.

Altitude does not equate to orbital. As others posted, it was far short of orbital velocity.

 

[Michel Van]

hi Broncazonk
you look on wrong page at Encyclopedia Astronautica

if you wanted X-15 goes in orbit, take the X-15B proposal that's a X-15 stap-on a Navaho G-38 boosters
http://astronautix.com/craft/x15b.htm
http://astronautix.com/lvs/navaho.htm

 

[airrocket]

X-15 SERJ Delta wing or the standard wing sRLV . The orbital version are laughable the SERJ on the other hand would've been an excellent sRLV.

 

[Orionblamblam]

X-15 SERJ Delta wing or the standard wing sRLV . The orbital version are laughable the SERJ on the other hand would've been an excellent sRLV.

Ummm... no. SERJ is great for getting from a runway up to Mach 6 or so. Mach 6 just ain't that close to Mach 25.

 

[airrocket]

M6 way short of M2 and the TPS was far short of an orbital mission sooooo....SERJ is about as sexy an X-15 as you'll find. However I agree your ducted rocket...deeply cooled that is would have been a great follow-on propulsion system. B-52 to 40K AGL drop er then fire up the ducted rocket and ride er along the air breather corridor up to 120K AGL and M5 then close off the naturally asperiated air flow point er up (pop up) and go all rocket rest of the way up... on a ballistic path for a RSO ride. Like the old White Sands V2 flights. Yeah but those days are long gone along with the engineers and pilots.... couldn't even do the X-15 today unless you...well ...you know ...pay the ruskies to do it.

 

[Byeman]

Pay ruskin? What the heck is SpaceShip 1? What happened with the shuttle has nothing to do with US capabilities.

 

[airrocket]

SS1 going on ten years...sure it wasn't just a stunt....still no SS2 even Rutan has moved on to other projects...? For now I'll put my money on the good old Russian spaceships.

 

[lippischh]

i think to accomplish that that need some modification on the X-15 to be a waverider, and......... removable huge boosters B)

 

[DSE]

i think to accomplish that that need some modification on the X-15 to be a waverider, and......... removable huge boosters B)

A lifting body would be more suitable. A waverider is optimized for a specific design Mach number, ok for a cruise vehicle, not an accelerator.

Remember:
waverider = lifting body
but lifting body != waverider

 

[TomcatViP]

hi Broncazonk
you look on wrong page at Encyclopedia Astronautica

if you wanted X-15 goes in orbit, take the X-15B proposal that's a X-15 stap-on a Navaho G-38 boosters
http://astronautix.com/craft/x15b.htm
http://astronautix.com/lvs/navaho.htm

Commercial spot of it:

https://youtu.be/nJP4iqoQ7u8

 

[Archibald]

It's not a matter of flying high, it is a matter of flying FAST and fight a logarithm.

rocket equation:
total delta-v = 9.81*specific impulse*ln(vehicle full mass with payload and propellants / vehicle full mass with payload and no propellants)
- delta-v to Earth orbit can't be tweaked, it's 9.3 km/s or bust (suborbital)
- 9.81 is Earth pull of gravity and can't be changed either
- specific impulse is very limited for conventional rockets, either 350 or 460 for LH2
- then the logarithm - ln - makes things even harder

In the end in the rocket equation most parameters are either fixed or with very tight margins.

Simple example
9.81*450*ln(200/20) = 10164 m/s
That's 10 km/s, enough to go into Earth orbit. Fine.

Except that...
- 9.81can't be changed
- 450 is a SSME in a good day
- 200 metric tons includes: the vehicle, its payload, crew, propellant tanks FULL (including LH2 which is a PITA)
- 20 metric tons includes: the vehicle, its payload, crew, propellant tanks EMPTY

The trick is to pile up the entire vehicle, minus the propellant, into 20 metric tons. Then add the props and it jumps to 200 tons. If you exceed those mass margins (22 metric tons or more), the vehicle will never go into orbit...