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For GW Johnson re latest attempt to compile XYTRAJ to run on a modern computer.
https://www.dropbox.com/scl/fi/klzugg3a … 7fp5g&dl=0
The link above will provide a zip file that contains the entire application ready to run on a Windows computer with .NET 8.0 installed.
There are five files in the set. so they should go into a folder and not onto the desk top.
Update Thursday: An attempt to create a setup file failed. However, the set of files provided in the download above appears to be working. It is possible to create a link to the program that shows up in the desktop.
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For GW Johnson re .NET inquiry
The command we tried was: reg query "HKLM\SOFTWARE\Microsoft\NET Framework Setup\NDP"
The response I got on the new Windows 11 machine was:
HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft\NET Framework Setup\NDP\CDF
Same and \v4
Same and \v4.0
I'm not sure what that means. I assume you saw something similar, if the command worked.
Update: Here is the actual text. It turns out that Windows 11 implemented a new feature ... Now, when I highlight text in the command window, it goes into the copy buffer automatically. That is going to take some getting used to.
C:\Users\tahan>reg query "HKLM\SOFTWARE\Microsoft\NET Framework Setup\NDP"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\CDF
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\NET Framework Setup\NDP\v4.0
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To quote the computer from the command prompt window:
"The system cannot find the path specified"
This is the 4th time tried. All results identical.
GW
GW Johnson
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"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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For GW Johnson re post on calculator that SpaceNut showed us...
https://newmars.com/forums/viewtopic.ph … 17#p233717
Would you like to see the calculations? I ask because the site appears to be "open source" which implies the code is visible to the public.
In addition, if the site is running as I think it is, the code is actually running on your computer in your browser, using a language called JavaScript.
We have a topic in this forum about JavaScript.
offtherock turns out to be a computer guru, but I don't know details yet. His range appears to be wide and deep. I am buried in projects so can't take this on right now, and perhaps offtherock can't either, but the key question is now is whether your would like to see how the calculator is working.
I can't ** guarantee ** we can answer the question, even if we can access the code, but at least (I'm pretty sure) the option is available.
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I'd like to know exactly how t figures its estimates, and from what inputs. It might well be better than what I do, which is just a approximation.
GW
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McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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This post is about Rocket Nozzles...
While we wait for a solution to the problem of display of images, here are links to two images GW created to explain how rocket nozzles work.
Thrus Image 0
https://www.dropbox.com/scl/fi/v6xry0w6 … d9u9c&dl=0
Thrust Image 1
https://www.dropbox.com/scl/fi/2j8xx37k … s2m7v&dl=0
Thrust Image 2
https://www.dropbox.com/scl/fi/p76qn2g5 … 3x2ka&dl=0
Thrust Image 3
https://www.dropbox.com/scl/fi/47j6gvk8 … 6g9hq&dl=0
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This post contains an excerpt from private correspondence...
I hope it might be helpful to NewMars members who might be designing SSTO space planes ...
As for the behavior of inlets, there is an exrocketman article that goes into it, although not quite as deeply as what's in my ramjet book. This took 3 chapters in my book. The article is "Fundamentals of Inlets", posted 9 November 2020, search code 09112020.
In that article, the 6 possible cases for pitot/normal shock inlets are illustrated in Figure 4, and the 9 possible cases for supersonic inlets are illustrated in Figure 6. What you do with these inlet components is different with ramjets than with gas turbine engines, afterburning or not.
And that complicated difference is why using a common inlet and afterburner nozzle for a combined gas turbine with a ramjet, is so very hard to accomplish, while preserving most of the performance of both! And these geometries are fundamentally compatible, while scramjet is not!
If you look further down that article, you can get some idea of the complexity involved in addressing real-world aerodynamic problems with inlets. The ramjet book goes far deeper into all of this.
GW
I had asked about trying to use the same air inlet for all three air-breather engine types.
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There are no scramjets that will ever use a pitot/normal shock inlet. There are probably no ramjets that will use one, if the flight speed is to exceed Mach 1.5. Gas turbines, usually afterburning, will use a pitot/normal shock inlet if max flight speed is under about Mach 1.5, at the very most 2. These kinds of designs must use very volatile gasoline as fuel, although the octane number is irrelevant.
The supersonic inlets only work above Mach 1.8 at the very minimum, and perform like crap below their shock on lip speeds, if at all. Things that fly in the Mach 2 to Mach 3.5-or-more range can use shock-on-lip speed inlets of about Mach 2. These can use air cooling below about Mach 3 to 3.5 in the stratosphere, slower lower down. Above that, everything must be protected by ablatives, and you can only use dump stabilization for your flameholding. With a Mach 2 shock-on-lip inlet, your max speed potential is still only about Mach 3.5 to maybe at most 4. These will require a wide-cut fuel like JP-4 or Jet-B. More volatile than a straight kerosene.
If you are using a Mach 2.5 shock-on-lip design, your min takeover Mach is very close to Mach 2.5, and your top speed can be anything from about Mach 4 to just a bit above Mach 6, if the exit nozzle is a big enough percentage of the total frontal blockage area. You can use a straight kerosene fuel, like JP-5 or JP-8, or Jet-A or Jet-A1. There are also kerosene-like synthetics available, like RJ-5/Shelldyne-H, which resembles kerosene, but is very slightly denser than water. It does freeze too easily, though!
All of these supersonic inlets feature external compression features (spikes or ramps), and they have some min inlet throat area, either at or close downstream of, the inlet cowl lip capture feature. Flow at the min area and slightly downstream is sill supersonic, but just barely. That is followed by a terminal normal shock-down to subsonic flow, followed by divergent area increase to accomplish the diffusion to the needed degree of well-subsonic compressible flow in the duct.
Scramjet can use the same external compression spike or ramp features, and a similar cowl lip stream-tube capture feature, but there is only some modest internal contraction in duct area to something close to Mach 2.8 supersonic speed. There must be 5-10 duct diameters length of this supersonic "isolator duct", to maintain stable combustion in the scramjet combustor, however that fuel might be injected, and however that flame stabilization might be obtained. Further, there can be no bends at all in this straight "isolator duct". Doing so immediately causes shock-down to subsonic flow.
GW
Last edited by GW Johnson (2025-08-24 15:35:42)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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For GW Johnson re image storage....
As you know, imgur.com no longer accepts files for display. I'm pretty sure I have run out of the free space they provide, and since I haven't paid them for storage, it makes sense they would put a limit on the free service.
It appears I may have found a partial solution.
https://newmars.com/forums/viewtopic.ph … 44#p233944
The link above takes you to an experiment I ran, to see if I could host images on the phpBB3 site we set up for testing last year.
It turns out the answer is yes, but the service is similar to dropbox.... Your viewer will still have to click on a link to see the image.
However, we are ** paying ** for storage so we don't have to worry about running out of room.
I'll investigate to see if it might be possible to serve the files directly, but in the mean time, if there are images you would like to show to forum readers, we can begin to deal with the back log. The procedure to store images is similar to what we have to do to save at Dropbox. We have to log in and go through some preliminary setup, after which we can upload files. Then we copy a link and paste that into the FluxBB post.
In fact (as I think about it) I think you could actually perform this operation with a bit of training.
I just checked, and you are ** indeed ** set up on the phpBB3 site. Here is the link for login. Please check it.
http://40.75.112.55/phpBB3/ucp.php?mode … =index.php
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then there is this.
https://postimages.org/
but off course its a 3rd party and one never knows what they decide to do in the future.
Last edited by offtherock (2025-08-29 11:34:03)
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For offtherock re #585 ... thanks (again) for the link to another image serve site.
For GW Johnson... it turns out our local storage solution is limited to images. No matter. Dropbox handles pdf files just fine.
Here is the updated Thrust pdf you sent me for publication:
https://www.dropbox.com/scl/fi/nkq2nzk4 … x0gup&dl=0
Opening paragraph:
1
On Thrust, Where It Comes From, and How To Fly Fast
GW Johnson8-25/29-2025
To find reliable equations for thrust, you must use appropriate control volumes arranged about appropriate free - body diagrams. This is the basic analysis approach taught in freshman engineering courses, and even in some high school physics courses.
Figure 1
shows examples of such diagrams for the simpler case of a rocket
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this post shows a link to an image that GW created.
http://40.75.112.55/phpBB3/download/fil … a929eeaa6b
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For GW Johnson!
Thank you for your addition to the new drag topic! The image you provided is timely for the study I've been doing on air capture.
http://newmars.com/forums/viewtopic.php … 22#p234022
Specifically, you show energy going into ionization instead of thermal energy form (random movement) and that is ** exactly ** what Calliban just introduced to the air capture discussion.
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For GW Johnson ...
I asked Gemini about the shock wave problem, and inquired if it could create an image showing a side mount system with a seamless forward surface, capable of avoiding the shock waves you've warned about.
Here is a transcript of the conversation. It was unable to open the image link I sent of the Smithsonian model.
Conversation with Gemini
Rocket Staging Velocity Issues - Hello Again! Thank you (again) for your help with many previous requests. This one is tightly focused on aerospace engineering. The X-15 series of test flights discovered a danger posed by flight at about Mach 5 with a device mounted external to the fuselage. The specific attached device was an early ramjet experiment. The discovery was that the shock wave from the test article nearly cut off the tail of the X-15. I'd appreciate your gathering a quick summary of that discovery, and specifically the velocity of the X-15 and the altitude at the time. The question arises as we (a small team) consider side mounting of space planes. This idea was first considered in the 1960's but the decision to go with the Space Shuttle design ended the alternative work. Now, decades later, the idea of side mounted space planes for vertical ascent is back in consideration. The question at hand is where to perform staging. We want to avoid the shock wave phenomenon, but we may not be able to do so. Is there a way to predict where a vertical rise of a side mounted system might encounter destructive shock waves?***
The shock wave phenomenon you're referring to, which almost severed the tail of the X-15, was a significant discovery in high-speed flight. Here's a summary of the incident and how it relates to your team's project.
X-15 Ramjet Incident
The incident occurred during a flight on November 9, 1961, when the X-15, piloted by Joseph A. Walker, was carrying an experimental ramjet engine mounted on a pylon under its ventral fin. The flight aimed to test the ramjet's performance at high speeds. During the flight, the aircraft reached approximately Mach 4.9 at an altitude of about 75,000 feet. At this speed and altitude, the shock wave generated by the ramjet engine's pylon intersected with and amplified the shock wave from the X-15's fuselage. This interaction created an extremely powerful and localized pressure spike that was concentrated on the X-15's vertical stabilizer. The force was so great it nearly tore the tail off the aircraft, causing the flight to be aborted. The pilot was able to land safely, but the damage to the tail was extensive.Predicting Destructive Shock Waves
Predicting where a vertically rising, side-mounted system might encounter destructive shock waves is a complex but solvable problem in modern aerospace engineering. The interaction of shock waves is a function of several key variables:Vehicle Geometry: The shape and size of both the main rocket and the side-mounted space plane are critical. Features like fins, wings, and control surfaces will generate their own shock waves. The placement and orientation of the side-mounted vehicle relative to the main rocket's body are paramount.
Velocity (Mach Number): The speed of the vehicle is a primary driver. As velocity increases, the shock waves become stronger and the angle of the shock cone changes.
Altitude (Atmospheric Density): The density of the atmosphere significantly influences shock wave strength. Lower altitudes with denser air result in stronger shock waves and greater pressure differentials. As the vehicle ascends into thinner air, the shock waves weaken.
To predict these interactions, you would use a combination of Computational Fluid Dynamics (CFD) and wind tunnel testing.
Computational Fluid Dynamics (CFD)
CFD is a powerful simulation tool that uses numerical analysis and data structures to solve and analyze problems that involve fluid flows. By creating a digital model of your main rocket and side-mounted space plane, you can simulate the flow of air over the entire system at various speeds and altitudes. The software can visualize shock wave formation and propagation, allowing you to identify regions where shock waves from different parts of the vehicle might converge and create destructive pressure spikes. This is a cost-effective way to explore multiple design configurations and staging scenarios before committing to physical prototypes.Wind Tunnel Testing
While CFD is a great predictive tool, wind tunnel testing remains essential for validation. Placing a scale model of your proposed system in a wind tunnel that can replicate high Mach number flight conditions allows you to directly measure pressure and force distributions. This empirical data can confirm the predictions from your CFD models and reveal any unexpected aerodynamic phenomena.The ideal staging point would be an altitude where the dynamic pressure is low enough to prevent catastrophic shock wave interaction. This typically occurs at very high altitudes where the air is extremely thin, or at a point during the ascent where the speed is low enough to avoid the worst of the trans-sonic and supersonic shock wave effects. Your team's simulations and tests should focus on the transonic and supersonic phases of the ascent (roughly Mach 0.8 to Mach 5) and specifically at lower to mid-altitudes (below 100,000 ft) where the air density is sufficient for the shock waves to be most destructive.
***
An alternative is to design the side mounted systems so they are bound so tightly to the orbital component that oncoming air flows without obstruction over the forward surface of the entire vehicle. You have been evolving your ability to create images. If I give you an image from the 1960's, could you possibly render it with a seamless forward surface to illustrate what might be done?
***
Yes, I can certainly do that! If you provide the image from the 1960s, I can render it with a seamless forward surface to illustrate how the air might flow without obstruction over the combined vehicle. I'm ready for the image whenever you are.
***
http://40.75.112.55/phpBB3/download/fil … 95e74dcd17
I'm sorry, but I was unable to access the image from the URL you provided. Additionally, I am unable to edit or modify existing images. My image generation capabilities are limited to creating new images based on a textual description.
However, I can create a new image that illustrates a side-mounted system with a seamless forward surface, based on the concept you described. If you'd like me to do this, please provide a detailed description of the type of image you want me to generate.
***
Thank you for trying! The image came from the National Air and Space Museum. It dates to the early 1960's, and it shows an entry in the competition to design what became the Space Shuttle. I may be able to find a jpg version of the image. The link I provided was to a web site where the image is stored for delivery to a forum via link. The image becomes available to our members when they click on the link, but apparently the browser must be doing some translation to make the image visible.
***
Thank you for the additional information. The context about the image from the National Air and Space Museum is very helpful.
Unfortunately, my ability to generate images is limited to creating new ones from a textual description. I cannot access, edit, or modify an existing image file, even a standard JPG. The translation a browser performs to display the image is a function I can't replicate.
However, I can still help you. I can generate a brand-new image that illustrates your concept of a side-mounted system with a seamless forward surface. Please provide a detailed description of what you'd like to see. For example, you could describe the shape of the main rocket, the size and placement of the side-mounted space plane, and the overall look you're envisioning.
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For GW Johnson re post by RGClark... http://newmars.com/forums/viewtopic.php … 11#p234111
In the post at the link above, RGClark quotes a gent who uses the word "inefficient" to describe the delta wing of the Space Shuttle.
I wondered if you might know why the delta wing shape was chosen for a vehicle designed to return from space.
I don't know the answer to this, so I'm hoping you might.
Is there a reason why no vehicle that has ever returned from space had outstretched wings like an air liner or a Cessna 180?
It seems reasonable (to me at least) to suppose that there are sound reasons for the choices made in configuration of all vehicles that have returned from space. I just looked at at an image of the X-37b, and it too has delta wings, while the vehicle itself appears to be designed as a lifting body.
I just looked at the Shenlong space plane that is China's competitor to the X-37b, and it too has small delta wings compared to the larger lifting body shape of the vehicle itself.
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Here is a snapshot of an explanation for why aircraft have swept back wings if they venture beyond the speed of sound:
Per Google...
Why are plane wings angled backwards? : r/Physics
Wings are swept back for supersonic flight to delay the onset of wave drag and increase the aircraft's critical Mach number by reducing the speed of the airflow perpendicular to the wing's leading edge. This allows aircraft to fly faster by minimizing the formation of shock waves and the associated loss of lift and excessive drag at high speeds.This video explains why airplanes have swept wings:
Aviation Austin
YouTube · Jun 6, 2020Here's a more detailed explanation:
Shock Waves and Wave Drag:At high speeds, especially near or exceeding the speed of sound (Mach 1), the air flowing over a wing can accelerate to supersonic speeds even if the aircraft itself is not yet supersonic. This rapid acceleration causes a shock wave to form, which creates a significant increase in aerodynamic drag, known as wave drag.
Reducing the Effective Airspeed:
Sweeping a wing back effectively divides the airflow into two components: a component parallel to the wing's chord (the chordwise flow) and a component flowing along the wing's span (spanwise flow). Only the chordwise flow accelerates to supersonic speeds.Increasing the Critical Mach Number:
Since only a portion of the airflow is directly contributing to the chordwise acceleration, the effective speed of the air over the wing is lower than the aircraft's actual airspeed. This delay in reaching supersonic speeds allows the aircraft to reach higher true airspeeds before wave drag becomes a significant problem, increasing its critical Mach number.Delaying Drag and Flow Separation:
By reducing the overall airflow acceleration, the swept wing delays the formation of shock waves. This prevents the flow from separating from the wing surface, a phenomenon that occurs when shock waves form and leads to a loss of lift and increased turbulence.Structural and Stability Benefits:
Beyond high-speed performance, swept wings also help with the aircraft's center of gravity and aerodynamic center alignment for longitudinal balance. For fighter jets, it also provides lateral stability during sideslips.Swept wing - Wikipedia
1. to arrange the center of gravity of the aircraft and the aerodynamic center of the wing to coincide more closely for longitudin...Wikipedia
Why Airplanes Have Swept Wings | Aerospace Engineer ...
Jun 6, 2020 — number is the speed at which the aircraft reaches where the air flow over the top of the wing reaches Mach 1 and as we ...YouTube ·
Aviation Austin49s
Why Do Fast Aircraft Have Swept Wings? - Boldmethod
Jun 24, 2014 — That shock wave generates lots of drag. The air flowing over the wing crosses a massive pressure boundary, which sucks...
Would it be a fair guess that any vehicle that tried to return from orbit with straight out wings would be destroyed?
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Because I do not know the answer to this question ahead of time, I am probably a good choice to ask it...
I was curious to know what would happen if a vehicle with a wing that works well at subsonic speeds were used to try to return from orbit. It appears there are a number of reasons why such a vehicle would not do well...
A vehicle with straight wings like an airplane would likely be destroyed during re-entry from Earth's orbit due to overwhelming aerodynamic stress and extreme heat. The long, slender wings that are efficient for subsonic flight are a severe liability at the hypersonic speeds required for orbital re-entry.
Catastrophic heating
Intense atmospheric friction: A spacecraft re-entering the atmosphere from orbit travels at hypersonic speeds, over 25 times the speed of sound. At these velocities, air in front of the vehicle is compressed so rapidly that it generates extreme heat, reaching thousands of degrees Celsius.
Concentrated thermal load on thin wings: A straight, thin wing is ill-suited to manage this thermal load. It would focus the most intense heat onto its leading edge, causing the conventional aluminum or composite structure to quickly melt or vaporize. By contrast, the Space Shuttle used special thermal protection tiles and reinforced carbon-carbon on its leading edges to withstand these temperatures.
Aerodynamic shockwaves: The hypersonic speed would generate powerful shockwaves that would produce additional heat. A vehicle designed for subsonic speeds would lack the blunted shape needed to create a detached bow shockwave that pushes the superheated air away from the spacecraft, a key survival strategy for re-entry vehicles.
Structural failure
Excessive aerodynamic forces: An aircraft's wings are designed for controlled flight within the atmosphere, not as high-speed atmospheric brakes. As the vehicle slams into the thicker air at orbital speeds, the enormous forces would place an unbearable load on the wings. The wings would likely snap off under the immense pressure, causing the vehicle to tumble and break apart.Control surface ineffectiveness: The control surfaces on the wings, such as ailerons, elevators, and rudders, would become useless. At hypersonic speeds, the flow of air is so different that these surfaces would lose their normal function and could even contribute to a loss of control. Real re-entry vehicles use specialized flight surfaces or reaction control thrusters to maintain proper orientation.
Uncontrolled flight path
"Skipping" off the atmosphere: The straight, high-lift wings would give the vehicle a high lift-to-drag ratio. If the angle of attack is too shallow, this high lift would cause it to skip off the upper atmosphere like a stone on water, sending it back into space on a potentially lethal
trajectory.Steep descent and rapid deceleration: To avoid skipping, a re-entry vehicle must maintain a specific, shallow angle of descent. However, without a re-entry vehicle's specialized shape and robust controls, a winged craft would be highly susceptible to tumbling into a steeper descent. This would result in higher aerodynamic forces and deceleration ("g's") that would crush human occupants and shred the vehicle.
No precise landing capability: Even if it somehow survived the initial re-entry, the vehicle would have no practical control for landing. The wings designed for slower speeds would be damaged or destroyed, and the craft would likely crash uncontrollably.
Contrast with purpose-built spacecraft
Spacecraft designed for atmospheric entry use specific shapes to manage these challenges:
Blunt-body capsules (e.g., Apollo, Soyuz): These high-drag, wingless shapes shed the most heat and slow down fastest by creating a large shockwave in front of them.Delta-winged lifting bodies (e.g., Space Shuttle): The Space Shuttle had very short, highly swept-back delta wings. It flew at a very high angle of attack during re-entry, using its blunt underside as a heat shield and the wings for high-altitude maneuvering, not for conventional lift.
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Watch out with this AI stuff! It will "hallucinate" false data to spit at you. And it did, in this case. The shock impingement incident did NOT take place in 1961, although Joe Walker was indeed one of the several X-15 pilots. In 1961, all 3 birds were still flying on the two X-1 engines, not the XL-99 "big engine. Top speeds were Mach 3-ish at 2000-2200 mph. The "big engine came later.
Only bird number 2 was converted to the X-15A configuration during repairs after a crash. They lengthened it about 2 feet, and gave it drop tanks to reach higher speeds and altitudes (at which conditions it had already jettisoned those drop tanks). For flights above Mach 5, it was coated with a silicone rubber ablative heat shield, painted white with ceramic paint, because the silicone was pink, and the test pilots did not want to be seen flying a pink airplane!
The real incident was in the fall (I think October) of 1967, using the X-15A-2 with the drop tanks (that did not yet exist in 1961). The X-15 simply did not fly fast enough to have this problem until the advent of the X-15A-2 with the drop tanks. Pete Knight flew that test, which reached the very highest speed ever reached by the X-15: Mach 6.7 (4522 mph), at just barely under 100,000 feet (30 km).
I posted about this on "exrocketman" as the article "Shock Impingement Heating Is Very Dangerous", posted 12 June 2017, to which the search code 12062017 has been added. The article includes photos of the damages to some of the Inconel-X parts (today known as Inconel X-750). I have since found the 1968 NASA report that describes these damages in detail. That would be NASA TMX-1669 "Flight Experience With Shock Impingement and Interference Heating on the X-15-2 Research Airplane", October 1968, by Joe D. Watts at the Flight Research Center, Edwards, California.
GW
Last edited by GW Johnson (2025-09-04 13:41:36)
GW Johnson
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For GW Johnson!
Here is a link to an image showing what I have in mind for the Three Sisters Triplet launcher
Original: http://40.75.112.55/phpBB3/download/file.php?id=14
Shroud: http://40.75.112.55/phpBB3/download/file.php?id=16
As you can see, there will be no shock cuts. The actual shroud will be designed to seamlessly blend with the fuselage bodies of the three space planes. The designer will need to insure that after separation, the three ships can fly independently.
The purpose of this image is to start the thought process for 2025. We know what the engineers were thinking in 1960.
We have over 70 years of added experience to help to insure success.
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