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I would argue that our tanks are an integral part of the wing structure, so size is not that critical as if it were a tank separate from the structure. What I am envisioning is a wing structure cast out of aluminum foam with cylindrical tanks embedded in it, which are aligned with the wing leading edge and parallel to it. The exterior alu-structure is then covered with more heat
resistant material. Alu is suitable for cryogenic storage. Nearly all our LH2-LO2 fits inside that wing volume.
Aluminum tanks can be used to store liquid hydrogen. They are commonly used for this purpose due to their good mechanical properties at very low temperatures. While other materials like stainless steel are also used, aluminum alloys are particularly well-suited for the extreme cold conditions required for liquid hydrogen storage. Here's why:
Cryogenic Compatibility:
Liquid hydrogen is stored at extremely low temperatures (around -253°C or 20 K). Aluminum alloys maintain their mechanical strength and integrity at these temperatures, making them suitable for cryogenic applications.
Material Selection:
Austenitic stainless steels and aluminum alloys are the most commonly used materials for liquid hydrogen storage vessels.
Specific Applications:
Aluminum tanks are used in various applications involving liquid hydrogen, including:
Rocket fuel storage: Aluminum tanks have been used in rockets for storing liquid hydrogen fuel for a long time.
Aircraft fuel tanks: Aluminum tanks are being explored for storing liquid hydrogen in aircraft.
Industrial and portable applications: Aluminum is also used in smaller, portable tanks for various purposes, including industrial gases and even paintball tanks.
Friction Stir Welding:
Friction stir welding (FSW) is a technique particularly well-suited for joining aluminum components in liquid hydrogen tanks. FSW preserves the material's properties and creates a leak-proof weld, which is crucial for cryogenic applications.
Type 3 Hydrogen Tanks:
Type 3 hydrogen storage tanks, commonly used in vehicles, feature an aluminum liner and a carbon fiber overwrap.
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It would appear that this spaceplane concept is intended to do a lifting flight to orbital-class speeds. That is essentially trying to fly reentry in reverse, more or less, something discredited since the X-15 days in the early 1960's. The drag will be horrendous at hypersonic speeds, and the aeroheating far worse. Even NASA knew better than to try that, when it kluged-up its spaceplane notion as the space shuttle: vertical rocket launch to get out of the atmosphere as quickly as possible, leaving it before you get high supersonic, much less very low hypersonic. Their trajectory was non-lifting ballistic, to get minimum drag. And it worked!
As for airbreathing vs rocket, there is far more to the picture than just specific impulse, and in NONE of these postings can I find a recognition of that. Ramjet and scramjet, both airbreathers, will have a thrust at any given speed that is at least approximately proportional to the ambient air pressure. This shows up as combustion chamber pressures only about 3 to 6 times ambient. Above about 100,000 to 125,000 feet, 3 to 6 times nothing is still nothing for chamber pressure (it likely will not burn at all, such low pressures), which in turn means essentially nothing for thrust. It WILL NOT accelerate nor will it climb, because vehicle mass does NOT decrease with low air pressure the way thrust and drag will. That effect is called "service ceiling", and rockets do not suffer from it. But ALL airbreathers do. Ramjet, scramjet, turbojet, piston, and airbreathing combined cycle, you name it.
Aeroheating during such an ascent is your other enemy. The total temperature in the stream adjacent to your vehicle is pretty close to the driving recovery temperature for heat transfer. At only Mach 3.5 in the stratosphere (below about 70,000 feet), this is 886 F. At only Mach 5 same altitudes, it is 1880 F. At Mach 10 it is 7730 F, which explains why the vehicle is fully surrounded by an ionized plasma sheath through which no radar/radio can penetrate and no visible light can see. Anything unable to cool adequately will quickly (in seconds) soak out to similar temperatures. And unlike reentry, your time spent at such conditions is orders of magnitude longer than 3-4 minutes of re-entry, precisely because most of your speeds are far, far below orbital class. And that last is why you do NOT want to try to fly reentry-in-reverse!
The max recommended soak-out service temperature of a carbon composite with organic binder would be about 200-250 F. Max for aluminum is about 300-350 F. Max for both titanium and low-carbon steel is about 700-800 F. Max for almost all the austenitic stainless steels is about 1200 F although 316 and 321 will go a little hotter around 1600 F, and 309 and 310 will go hotter still to almost 1900 F. Of those, if you must have good cryogenic properties, only 304L in plate and sheet is weldable. That's why most earthly cryogenic tanks are far preferred to be made of it, not aluminum! The exotics like Rene 41 will go to about 2200 F. But they have no cryogenic strength, and they are hard to machine and hard to join.
Don't launch this thing horizontally, and expect the wings to do you any good during ascent. Above about 100,000 feet, they simply cannot, even if they are huge! The air is just too thin! As I said, this has been known, theoretically and experimentally, since the X-15 days. Thinking you are going to do this single stage is just nonsense. It has been nonsense for over 6 decades now! Which never stopped people proposing, and the government funding, proposals to explore it anyway.
GW
Last edited by GW Johnson (2025-08-12 15:22:35)
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Take off from a runway search
AI Overview
Determining the precise runway launch length for a hypothetical "space plane" or future runway-launched spacecraft is complex, as it depends heavily on the specific design, weight, and desired flight profile of the vehicle.
However, we can look at existing and proposed spaceplane systems and their runway requirements for landing, which can provide insights into potential launch needs:
Space Shuttle: The Space Shuttle orbiters landed on a 15,000-foot (4,572-meter) concrete runway at the Kennedy Space Center (SLF), according to NASA.gov. While the Shuttle launched vertically, this demonstrates the significant runway length required for landing a vehicle returning from space at high speeds.
Stratolaunch: This aircraft, designed to air-launch rockets carrying spacecraft, requires a 12,000-foot (3,700-meter) runway for takeoff.
Radian One: This proposed spaceplane aims to take off horizontally from a runway and fly directly into orbit. While the exact runway length needed is still under development, a Futurism article suggests it will utilize a rocket-powered sled for initial acceleration.
Virgin Galactic's SpaceShipTwo: This suborbital spaceplane takes off on a 2-mile (approximately 10,500 feet or 3,200 meters) runway, attached to a carrier aircraft, before being released at altitude to proceed under its own power.
In conclusion, while there isn't a universally standardized runway launch length for spaceplanes, based on existing and proposed systems, it's evident that runways in the range of 10,000 to 15,000 feet (approximately 3 to 4.6 kilometers) or longer would be necessary to accommodate future spaceplanes designed for horizontal takeoff, and even longer runways or additional launch assistance might be needed for orbital launches. This is considerably longer than the runways required for typical commercial aircraft, which generally fall within the 1,500 to 3,000 meter range.
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Just as a general idea for space planes.:
I feel strongly about a maglev assisted take off, to keep it purely SSTO you can cheat by spending more money on a horizontal launch platform to boost payload. I've also toyed with the idea of using steam vents along that rail to reduce air density by 40%.
The more extra external acceleration there is and less air drag there is for less fuel burn in return: the more useful payload you get up there.
I'm also fond of the idea of TSTO via air drop from an AN 225. In this case free extra altitude of 36,000 feet and mach 0.8 of extra given speed.
I've sent GW Johnson's reply to the board will reply him when I get answers to his points. As you might have guessed I'm liasing between the board and GW. So not all my words are mine in regards to communications here with him.
Take off from a runway search
AI Overview
Determining the precise runway launch length for a hypothetical "space plane" or future runway-launched spacecraft is complex, as it depends heavily on the specific design, weight, and desired flight profile of the vehicle.
However, we can look at existing and proposed spaceplane systems and their runway requirements for landing, which can provide insights into potential launch needs:
Space Shuttle: The Space Shuttle orbiters landed on a 15,000-foot (4,572-meter) concrete runway at the Kennedy Space Center (SLF), according to NASA.gov. While the Shuttle launched vertically, this demonstrates the significant runway length required for landing a vehicle returning from space at high speeds.
Stratolaunch: This aircraft, designed to air-launch rockets carrying spacecraft, requires a 12,000-foot (3,700-meter) runway for takeoff.
Radian One: This proposed spaceplane aims to take off horizontally from a runway and fly directly into orbit. While the exact runway length needed is still under development, a Futurism article suggests it will utilize a rocket-powered sled for initial acceleration.
Virgin Galactic's SpaceShipTwo: This suborbital spaceplane takes off on a 2-mile (approximately 10,500 feet or 3,200 meters) runway, attached to a carrier aircraft, before being released at altitude to proceed under its own power.
In conclusion, while there isn't a universally standardized runway launch length for spaceplanes, based on existing and proposed systems, it's evident that runways in the range of 10,000 to 15,000 feet (approximately 3 to 4.6 kilometers) or longer would be necessary to accommodate future spaceplanes designed for horizontal takeoff, and even longer runways or additional launch assistance might be needed for orbital launches. This is considerably longer than the runways required for typical commercial aircraft, which generally fall within the 1,500 to 3,000 meter range.
Last edited by PhotonBytes (2025-08-15 14:58:58)
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"Drag will be horrendous".
We are flying a lifting body with an L/D ratio of 3 to 5. So at any given point in the ascent, our drag is no more than about 1/3 to 1/5 of the vehicle's instantaneous weight, which is constantly decreasing. I highly recommend you spend sometime on our website exploring it and getting a general feel of the airframe and engine systems being proposed.
Above Mach 15:
The centrifugal lift becomes significant, and the drag will be even less for our L/D_max ascent profile.How can a lifting ascent be a reentry in reverse? Our ascent takes 30 minutes, our reentry 3 hours. The mass cannot increase during reentry back to lift off or takeoff mass. Shuttle reentry took over 30 minutes, not 3 - 5 minutes And our engine will gradually switch to all rocket, so we do not have a "service ceiling".
It would appear that this spaceplane concept is intended to do a lifting flight to orbital-class speeds. That is essentially trying to fly reentry in reverse, more or less, something discredited since the X-15 days in the early 1960's. The drag will be horrendous at hypersonic speeds, and the aeroheating far worse. Even NASA knew better than to try that, when it kluged-up its spaceplane notion as the space shuttle: vertical rocket launch to get out of the atmosphere as quickly as possible, leaving it before you get high supersonic, much less very low hypersonic. Their trajectory was non-lifting ballistic, to get minimum drag. And it worked!
As for airbreathing vs rocket, there is far more to the picture than just specific impulse, and in NONE of these postings can I find a recognition of that. Ramjet and scramjet, both airbreathers, will have a thrust at any given speed that is at least approximately proportional to the ambient air pressure. This shows up as combustion chamber pressures only about 3 to 6 times ambient. Above about 100,000 to 125,000 feet, 3 to 6 times nothing is still nothing for chamber pressure (it likely will not burn at all, such low pressures), which in turn means essentially nothing for thrust. It WILL NOT accelerate nor will it climb, because vehicle mass does NOT decrease with low air pressure the way thrust and drag will. That effect is called "service ceiling", and rockets do not suffer from it. But ALL airbreathers do. Ramjet, scramjet, turbojet, piston, and airbreathing combined cycle, you name it.
Aeroheating during such an ascent is your other enemy. The total temperature in the stream adjacent to your vehicle is pretty close to the driving recovery temperature for heat transfer. At only Mach 3.5 in the stratosphere (below about 70,000 feet), this is 886 F. At only Mach 5 same altitudes, it is 1880 F. At Mach 10 it is 7730 F, which explains why the vehicle is fully surrounded by an ionized plasma sheath through which no radar/radio can penetrate and no visible light can see. Anything unable to cool adequately will quickly (in seconds) soak out to similar temperatures. And unlike reentry, your time spent at such conditions is orders of magnitude longer than 3-4 minutes of re-entry, precisely because most of your speeds are far, far below orbital class. And that last is why you do NOT want to try to fly reentry-in-reverse!
The max recommended soak-out service temperature of a carbon composite with organic binder would be about 200-250 F. Max for aluminum is about 300-350 F. Max for both titanium and low-carbon steel is about 700-800 F. Max for almost all the austenitic stainless steels is about 1200 F although 316 and 321 will go a little hotter around 1600 F, and 309 and 310 will go hotter still to almost 1900 F. Of those, if you must have good cryogenic properties, only 304L in plate and sheet is weldable. That's why most earthly cryogenic tanks are far preferred to be made of it, not aluminum! The exotics like Rene 41 will go to about 2200 F. But they have no cryogenic strength, and they are hard to machine and hard to join.
Don't launch this thing horizontally, and expect the wings to do you any good during ascent. Above about 100,000 feet, they simply cannot, even if they are huge! The air is just too thin! As I said, this has been known, theoretically and experimentally, since the X-15 days. Thinking you are going to do this single stage is just nonsense. It has been nonsense for over 6 decades now! Which never stopped people proposing, and the government funding, proposals to explore it anyway.
GW
Last edited by PhotonBytes (2025-08-15 13:43:26)
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Your time comparisons are apples and oranges.
Reentry only takes 30 minutes if you time it from the reentry burn instead of the entry interface altitude of 140 km. From there, using a low-angle trajectory, it's about 3 to 4 minutes from entry at orbital speed to a fairly sudden drop from near-orbital speed to well-below orbital speed, the max-gee "point", which is several seconds long actually. The several-second-long max heating "point" precedes this by several seconds. Then within several seconds more, you are "out of hypersonics" at about Mach 3 speed, if you are blunt. That's 4-5 minutes from interface to out of hypersonics. It works this way because most of your descent is above half orbital speed, for a short time exposure to the most extreme entry heating. The peak gees is usually somewhere around 4 gees.
The ascent heating exposure is a lot longer than that, because most of your ascent time is for when you are below half orbital speed, and very little exposure time above it. While not as extreme, simple hypersonic heating is still quite severe. And you will NOT suddenly gain a lot of speed at 4-ish gees, unlike descent, because unless you are a rocket, there is no way your propulsion will support accelerations like that. The altitude is too high (around 40 km, near 140,000 feet) and the air too thin (almost a vacuum) for any airbreather to accelerate anything.
Using a rocket there is a waste of rocket propellant that should have been used instead on the non-lifting ballistic ascent trajectory that leaves the sensible atmosphere at only high-supersonic speeds, not even hypersonic.
GW
Last edited by GW Johnson (2025-08-15 14:02:00)
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Based on our Ascent-Descent.xls we have a maximum acceleration of 1.025 g during ascent and maximum deceleration of 0.225 g during reentry.
http://space-plane.org/files.htm
We currently switch to full rocket mode no later than Mach 18 and that is just above 55 km altitude in the ascent profile. Our original Mach-Isp profile from Nehemiah[1], dictated full rocket mode just below Mach 11 and that would be at 42 km altitude. But that made us run out of propellant before we get to orbit. So we extended air-breathing to Mach 18, requiring a novel engine design, otherwise SSTO will not happen.
This paper[2] simulates scramjet combustion at lower than typical dynamic pressures, 10 kPa, 20 kPA, 30 kPa, which matches our ascent profile.
Just read the abstract. At Mach 16, we have a dynamic pressure of 13.7 kPa while flying at 50.6 km altitude. So the claim that scramjets only work up to 40 km is not quite supported by CFD and experimental data (the paper has both). How much useful thrust they produce is a separate question though that only CFD can predict.
Shuttle reentry takes 30 minutes from 120 km entry interface. Maximum heating with communications blackout due to plasma is 13 minutes (not 3 - 4 minutes).
https://drive.google.com/file/d/1MinCYE … p=drivesdk
My notes added:
https://drive.google.com/file/d/1Mt578a … p=drivesdk
https://en.wikipedia.org/wiki/Atmospheric_entry
https://www.youtube.com/watch?v=Pp9Yax8UNoM
Skipping:
For a space plane, it might be that only a fraction of the vehicle’s maximum lift capability is required. This is very convenient because then the remaining lift can be then be used to keep the vehicle high in the atmosphere during the skip stage so it can cool off.
https://drive.google.com/file/d/1MwEEXl … p=drivesdk
https://www.orbiterwiki.org/wiki/GPIS_6:_Reentry
References:
[1] A Performance Analysis of a Rocket Based Combined Cycle
(RBCC) Propulsion System for Single-Stage-To-Orbit Vehicle
Applications
Nehemiah Joel Williams
https://t.me/c/1917559500/11081
[2] Research on combustion characteristics of
scramjet combustor with different flight dynamic
pressure conditions
Junlong Zhang*, Guangjun Feng, Haotian Bai, Kangshuai Lv, Wen Bao
https://www.sciencedirect.com/science/a … 0X23000196
Your time comparisons are apples and oranges.
Reentry only takes 30 minutes if you time it from the reentry burn instead of the entry interface altitude of 140 km. From there, using a low-angle trajectory, it's about 3 to 4 minutes from entry at orbital speed to a fairly sudden drop from near-orbital speed to well-below orbital speed, the max-gee "point", which is several seconds long actually. The several-second-long max heating "point" precedes this by several seconds. Then within several seconds more, you are "out of hypersonics" at about Mach 3 speed, if you are blunt. That's 4-5 minutes from interface to out of hypersonics. It works this way because most of your descent is above half orbital speed, for a short time exposure to the most extreme entry heating. The peak gees is usually somewhere around 4 gees.
The ascent heating exposure is a lot longer than that, because most of your ascent time is for when you are below half orbital speed, and very little exposure time above it. While not as extreme, simple hypersonic heating is still quite severe. And you will NOT suddenly gain a lot of speed at 4-ish gees, unlike descent, because unless you are a rocket, there is no way your propulsion will support accelerations like that. The altitude is too high (around 40 km, near 140,000 feet) and the air too thin (almost a vacuum) for any airbreather to accelerate anything.
Using a rocket there is a waste of rocket propellant that should have been used instead on the non-lifting ballistic ascent trajectory that leaves the sensible atmosphere at only high-supersonic speeds, not even hypersonic.
GW
Last edited by PhotonBytes (2025-08-16 10:56:33)
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Photonbytes:
I've slowly been looking at you postings and references, trying to understand what Spaceplane Corporation is actually trying to do.
A question: does your ascent presume near-optimal L/D ratio all the way up?
GW
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Most of the videos I post of my sim in Facebook have an 11deg fixed pitch just to keep things simple. However to answer your question: yes, max L/D ratio , and when that happens we have phuggoid oscillations! This is why were looking for a control specialist to further optimize.
Update:
Please tell him that I fly my ascent at maximum L/D attack angle but that results in significant phugoid (pitch) oscillations in the subsonic part of the flight. Once supersonic, these pitch oscillations are fairly damped though.
Photonbytes:
I've slowly been looking at you postings and references, trying to understand what Spaceplane Corporation is actually trying to do.
A question: does your ascent presume near-optimal L/D ratio all the way up?
GW
Last edited by PhotonBytes (Yesterday 08:50:17)
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For PhotonBytes re #34
Thank you for engaging with GW Johnson about the simulations of performance of a hypothetical space plane.
GW Johnson and kbd512 understand the term L/D ratio. I know that because I heard them discussing your simulation on Sunday.
However, many of us NewMars members are unsure what the term means in the context of a flight with increasing altitude.
For example, does the term "max L/D" mean the maximum ** possible ** L/D at any given instant, or does it mean the maximum L/D that might occur at the most favorable moment? It seems to me you must have multiple variables going on simultaneously as you build your simulation tables. The thrust may remain constant if it is from a rocket, but otherwise it will vary. The altitude is varying, and so is the density of air and velocity.
From listening to the discussion on Sunday, I get the impression interesting things happen when the vehicle approaches and surpasses the speed of sound. If you are computing a constant L/D ratio, then (I deduce) you must be ignoring the effects of flight at the transition to supersonic flight.
I hope you will continue reporting on your team's progress because there are few such teams around the world, and we only learn about the others from news reports.
As a side note.... GW Johnson estimates the inert fraction of a vehicle that can survive re-entry at about 40%. That estimate would apply to a vehicle as the X-37b, which is flying as a two stage reusable vehicles. He has estimated the inert fraction at 4% for a vehicle designed to reach LEO as SSTO using LH2 and LOX.
If your vehicle can achieve 4% inert, then it can simply take off vertically and return to Earth as a glider as Shuttle did.
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Update: Please tell him that I fly my ascent at maximum L/D attack angle but that results in significant phugoid (pitch) oscillations in the subsonic part of the flight. Once supersonic, these pitch oscillations are fairly damped though.
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To fly at one and only one L/D ratio, you would have to fly at one and only one angle of attack, thereby maintaining a constant lift coefficient and drag coefficient, at just the optimum values. The only possible way to accomplish that is to fly at one and only one value of dynamic pressure. Theoretically, that is possible to control. Practically, it is not, especially down low where you are trying to get started.
GW
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The attack angle for maximum L/D and the corresponding value were determined via CFD simulations while running through the full range of flight Mach numbers, 0.3 (takeoff) to 25 (orbit insertion). Both the attack angle and max L/D value change with Mach number. We have surface plots of lift, drag, and pitch coefficient, as well as L/D as functions of attack angle and Mach number at the bottom of our News page. At any time during the ascent we fly the vehicle at the attack angle for max L/D to optimize performance. L/D is derived from the lift and drag coefficients, L/D = Cl / Cd.
For PhotonBytes re #34
Thank you for engaging with GW Johnson about the simulations of performance of a hypothetical space plane.
GW Johnson and kbd512 understand the term L/D ratio. I know that because I heard them discussing your simulation on Sunday.
However, many of us NewMars members are unsure what the term means in the context of a flight with increasing altitude.
For example, does the term "max L/D" mean the maximum ** possible ** L/D at any given instant, or does it mean the maximum L/D that might occur at the most favorable moment? It seems to me you must have multiple variables going on simultaneously as you build your simulation tables. The thrust may remain constant if it is from a rocket, but otherwise it will vary. The altitude is varying, and so is the density of air and velocity.
From listening to the discussion on Sunday, I get the impression interesting things happen when the vehicle approaches and surpasses the speed of sound. If you are computing a constant L/D ratio, then (I deduce) you must be ignoring the effects of flight at the transition to supersonic flight.
I hope you will continue reporting on your team's progress because there are few such teams around the world, and we only learn about the others from news reports.
As a side note.... GW Johnson estimates the inert fraction of a vehicle that can survive re-entry at about 40%. That estimate would apply to a vehicle as the X-37b, which is flying as a two stage reusable vehicles. He has estimated the inert fraction at 4% for a vehicle designed to reach LEO as SSTO using LH2 and LOX.
If your vehicle can achieve 4% inert, then it can simply take off vertically and return to Earth as a glider as Shuttle did.
(th)
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