North American XB-70 and X-15 Delta

[archipeppe68]

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...

[JosephB]

Nice work!
Thanks

[simonbp]

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.

[archipeppe68]

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...

[fatjohn1408]

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.

[Rocket Science]

Bella lavoro Giuseppe!

[archipeppe68]

Bella lavoro Giuseppe!

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

[simonbp]

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.

[RanulfC]

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

[Vahe231991]

Here is an artist's rendering from North American Aviation company documents of the delta-wing X-15 being launched from the XB-70 mothership.

[laszlo]

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/)

Randy

I know that this is a bit of a necro, but this could be useful for anyone who finds this thread while searching for research material.

I just happen to be re-reading the NASA publication X-15 Extending the Frontiers of Flight https://www.nasa.gov/pdf/470842main_X_15_Frontier_of_Flight.pdf and it's even the section where it talks about considering the B-58 as a carrier craft. This is what they had to say about that:

The supersonic B-58 was attractive from a performance perspective, but looked less attractive
from the maintenance and availability standpoint. Nevertheless, on 22 January 1957, future X-15
pilot Neil Armstrong traveled to the Convair plant in Fort Worth to discuss the possibility of using
a B-58 to launch the research airplane. The first problem was that the 22-foot wingspan and 18-
foot tail-span of the X-15 both intersected the plane of the rearward-retracting main gear on the
B-58. This would have necessitated moving the entire X-15 forward of the desired location.
Convair engineers believed that this might be possible, but it would require designing a new nose
gear for the B-58 since the X-15 would block the normal nose gear. Another possibility was to
beef up the X-15 nose gear and use it while the pair was on the ground. The inboard engine
nacelles on the B-58 would likely need to be "toed" outward or simply moved further out on the
wing, and either would have necessitated major structural changes. Engineers would need to
design a way to fold the X-15 vertical stabilizer because they could not make room for it within
the B-58 fuselage without severing a main wing spar. The design of the B-58 included a
weapons/fuel pod that weighed 30,000 pounds, only slightly less than the X-15. However, the
baseline mission included using the fuel in the pod prior to dropping the pod, and the maximum
drop weight was only 16,000 pounds. This would necessitate a new series of tests to validate that
a heavier object would separate cleanly, especially at supersonic speeds. However unfortunately,
the B-58 was obviously not going to work.