Author Topic: North American XB-70 and X-15 Delta  (Read 5581 times)

Offline archipeppe68

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North American XB-70 and X-15 Delta
« on: 12/16/2013 07:24 pm »
Somewhere in mid '60s NASA planned to couple such stunning aircrafts, it didn't happened essentially for the X-15-3 lost.

Indeed it was joy for me to draw them togheter...

Offline JosephB

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Re: North American XB-70 and X-15 Delta
« Reply #1 on: 12/16/2013 09:23 pm »
Nice work!
Thanks

Offline simonbp

Re: North American XB-70 and X-15 Delta
« Reply #2 on: 12/17/2013 12:43 am »
Wonderful, thanks Giuseppe.

I do wonder about the separation maneuver, though, both because of the proximity of the XB-70's tail fins to the X-15's delta wing, and the XB-70's fatal wing tip vorticies. The SR-71/D-21 experience is that this would have been very dangerous.
« Last Edit: 12/17/2013 12:43 am by simonbp »

Offline archipeppe68

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Re: North American XB-70 and X-15 Delta
« Reply #3 on: 12/17/2013 11:14 am »
Wonderful, thanks Giuseppe.

I do wonder about the separation maneuver, though, both because of the proximity of the XB-70's tail fins to the X-15's delta wing, and the XB-70's fatal wing tip vorticies. The SR-71/D-21 experience is that this would have been very dangerous.

I fully agree, after the D-21 experience it would be really dangerous. The only other option would be an underbelly launch but the XB-70 main gear clearance got difficult to load the X-15 below...

Offline fatjohn1408

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Re: North American XB-70 and X-15 Delta
« Reply #4 on: 12/17/2013 11:47 am »
Wonderful, thanks Giuseppe.

I do wonder about the separation maneuver, though, both because of the proximity of the XB-70's tail fins to the X-15's delta wing, and the XB-70's fatal wing tip vorticies. The SR-71/D-21 experience is that this would have been very dangerous.

In the end, isn't it just a matter of which you try and push the X-15 through the shockwave? If you ask me the bigger the craft, the slower you need to go through the shockwave. Resistance by the shockwave will scale with the area of the craft, while the force with which the craft bounces against or perhaps through the shockwave scales with its mass and thus volume.

This is just top of my head. Issues at hand might be much more complicated.

Offline Rocket Science

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Re: North American XB-70 and X-15 Delta
« Reply #5 on: 12/17/2013 12:19 pm »
Bella lavoro Giuseppe! :)
"The laws of physics are unforgiving"
~Rob: Physics instructor, Aviator, Vintage auto racer

Offline archipeppe68

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Re: North American XB-70 and X-15 Delta
« Reply #6 on: 12/17/2013 05:18 pm »
Bella lavoro Giuseppe! :)

I want to thanks all the folks for the appreciation....

Offline simonbp

Re: North American XB-70 and X-15 Delta
« Reply #7 on: 12/18/2013 04:33 pm »
Wonderful, thanks Giuseppe.

I do wonder about the separation maneuver, though, both because of the proximity of the XB-70's tail fins to the X-15's delta wing, and the XB-70's fatal wing tip vorticies. The SR-71/D-21 experience is that this would have been very dangerous.

In the end, isn't it just a matter of which you try and push the X-15 through the shockwave? If you ask me the bigger the craft, the slower you need to go through the shockwave. Resistance by the shockwave will scale with the area of the craft, while the force with which the craft bounces against or perhaps through the shockwave scales with its mass and thus volume.

This is just top of my head. Issues at hand might be much more complicated.

The problem is thinking about it as fixed shockwaves. In reality, if the X-15 was released into the XB-70's shockwave, it would have pushed back on the XB-70. This would have created complex feedback effects that could have caused the X-15 to reimpact the carrier aircraft. That's exactly what happened with the SR-71/D-21 crashes, and is similar to the F-104 collision that killed the second XB-70.

If NASA/USAF had gone through with this program, they probably would have put the smaller vehicle semi-recessed in the XB-70's bomb bay. Due to length restrictions, that would have meant a very different looking vehicle than X-15 or X-15 Delta.

Offline RanulfC

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Re: North American XB-70 and X-15 Delta
« Reply #8 on: 12/18/2013 05:45 pm »
Wonderful, thanks Giuseppe.

I do wonder about the separation maneuver, though, both because of the proximity of the XB-70's tail fins to the X-15's delta wing, and the XB-70's fatal wing tip vorticies. The SR-71/D-21 experience is that this would have been very dangerous.

In the end, isn't it just a matter of which you try and push the X-15 through the shockwave? If you ask me the bigger the craft, the slower you need to go through the shockwave. Resistance by the shockwave will scale with the area of the craft, while the force with which the craft bounces against or perhaps through the shockwave scales with its mass and thus volume.

This is just top of my head. Issues at hand might be much more complicated.

The problem is thinking about it as fixed shockwaves. In reality, if the X-15 was released into the XB-70's shockwave, it would have pushed back on the XB-70. This would have created complex feedback effects that could have caused the X-15 to reimpact the carrier aircraft. That's exactly what happened with the SR-71/D-21 crashes, and is similar to the F-104 collision that killed the second XB-70.

As far as I've been able to find the SR-71/D-21 crash (single) was caused not by any interaction with the shock-wave, (there were successful test launches) but by the D-21 autopilot suddenly commanding a "dive" before it even encountered the shock-wave.
(The entire "reason" to launch something from the top/back of a supersonic-or hypersonic carrier is that in "cruise" mode the aircraft always has a slight "nose-up" attitude meaning the top shock-wave is higher above the aircraft and "wider" in that area.)

The idea here was that the X-15 would be released while the XB-70 did a "push-over"  to get seperation as the X-15 even with the delta wings probably would not have has as high a L/D as the XB-70. (Or the D-21 for that matter)

The problem with the XB-70s bomb bays (like all bomb bays actually) is they were individually mass limited to the amount of weapons they could carry and since they were "seperate" bays they didn't really have the ability to carry a large load over their length. Worse anything carried even "semi-recessed" would have adversly effected the airflow under the aircraft which would have effected performance.

"Top/back" carry was the only way to carry a "large" payload on the XB-70 without a total redesign effort which would have ended up with something like the supposed Blackstar carrier aircraft.

Now a plane that "could" have done a bottom-drop (given a whole lot of modifications but less than needed for the XB-70) was the B-58 Hustler modifed along the lines as proposed for the "Town-Hall" Air-Launched ICBM study (http://www.up-ship.com/apr/extras/townhall.htm / http://www.rocketryforum.com/showthread.php?57490-STUDY-SUMMARY-Project-quot-Town-Hall-quot-B-58-Hustler-Minuteman-Missile-ASAT-Spy-Satellite&s=4998e81151d6bcb95f8b99881fa7c16f)

Since the B-58 did not have a normal "bomb-bays" but a hard-back carry point system along its center line it did not have the problems a "normal" bomber would have had. As long as the center-line carry system could handle the weight, the landing gear could retract and the payload cleared the ground that was all that was required. Normally the B-58 is listed as carrying a maximum of 19,450lbs of "weapons" and an unstated (that I could find) amount of fuel in the center-line pod. Town-Hall took a "regular" Minuteman-II missile and cut 81 inches off the first stage booster to shorten the total length to 53 feet and a weight of around 52,000lbs. Nominally this would "work" for the X-15 at 50ft long and 34,000lbs flight ready... However... That "clearing the ground" part might be a killer. The X-15 was 13 feet high over twice the size of the Town-Hall Minuteman and the "span" of 22ft 4in might have played merry heck with the main gear retraction, even if they replaced the normal wing with the delta ones. From the illustrations in the Town-Hall reports with that much weight it looks like about 5 to 6 feet is all you have which is 7 to 8 feet "short" no matter what. You could "probably" gain something by over-filling the oleo's as per "AirLaunch" but that's probably less than a foot and you'd need to ensure you could still retract the gear properly. (Animations of the nose and main gear retract sequence can be found here: http://b58hustlerassn.net/)

The X-20 might have been a better fit :)

Than again I'm one of those "crazy" folks that thinks it would be rather 'interesting' to back-engineer a "modern" B-58 as a supersonic carrier launch 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?

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