Skyhiker-Skyhitch towed SSTO

[IsaacKuo]

I've finally figured out a way to use cable towing for all steps, eliminating the nose push tail ring.

The key is to use a half-loop cable rather than a line and drogue. The ends of the cable are attached to the wings, which keeps the cable clear of rocket exhaust.

The Skyhiker has a nose hook that looks like a navy jet's tail hook. But instead of being mounted underneath the tail, this nose hook is mounted above the nose.

To use, the hook is rotated up vertically so it sticks above the Skyhiker. A high angle of attack helps the hook poke well above the rudders. As the half-loop of the tow cable passes by slowly, the hook is inserted into the loop's gap and catches the bend at the rear.

[Jim]

I've finally figured out a way to use cable towing for all steps, eliminating the nose push tail ring.

So what is protecting the cable from aeroheating at 2km/sec?

If you are not going to answer questions posed to you or ignore points that show the infeasibility of the concept, I am going to ask for this thread to be locked.

[IsaacKuo]

I don't really have the inclination to argue with someone who doesn't think it's possible to pitch upward with an aircraft, braking while changing the heading to 15 degree upward (thus entering an upward ballistic trajectory).

Mid-air refueling is a thing that actually happens. Controlled gliding from orbit to a specific altitude and position actually happens. What's the point of arguing with someone who denies that these things can be done?

[IsaacKuo]

So what is protecting the cable from aeroheating at 2km/sec?

The thinness of the atmosphere at the altitudes used, along with choice of cable material to let it handle the heating that it does encounter. My guess is that some type of steel may be the best choice, since it can be pretty durable under a wide range of conditions.

[hkultala]

I don't really have the inclination to argue with someone who doesn't think it's possible to pitch upward with an aircraft, braking while changing the heading to 15 degree upward (thus entering an upward ballistic trajectory).

Mid-air refueling is a thing that actually happens.

Supersonic or hypersonic mid-air-refueling does not happen. Refueling is currently only performed on subsonic speeds, AND it's only performed when both aircrafts are under thrust.

Controlled gliding from orbit to a specific altitude and position actually happens.

.. with huge wings, when this specific altitude is 0 so that there is LOTS OF TIME to do the manouvering.

Trying to rendeznous something running at hypersonic speed is totally different thing than landing into stationary runway.

What's the point of arguing with someone who denies that these things can be done?

You are messing up completely different things. Much easier things are done and you are using this as a claim that much harder things can be done.

[Jim]

1.  I don't really have the inclination to argue with someone who doesn't think it's possible to pitch upward with an aircraft, braking while changing the heading to a 15 degree upward (thus entering an upward ballistic trajectory).

2.  Controlled gliding from orbit to a specific altitude and position actually happens.

The issue isn't me proving anything.  It's your concept and you have made many unsupported assumptions, that basically show a lack of understanding the environment

1.  We aren't talking about aircraft or "gliding".  This is a entry vehicle going at 2km/sec.  It is going hypersonic.   It would have to be at 50km altitude or more due to heating.  It can't "pull up".  Increasing lift is going to cause temperature to go too high (shuttle flew at 40 deg AOA, any lower and it would over heat).   The shuttle never climbed during entry

2.  No.  The shuttle did not glide to specific altitude, position and time.  It landed at a specific point but that is not the same.   The shuttle controlled energy and it flew a trajectory that was some what variable.

[hkultala]

So what is protecting the cable from aeroheating at 2km/sec?

The thinness of the atmosphere at the altitudes used, along with choice of cable material to let it handle the heating that it does encounter. My guess is that some type of steel may be the best choice, since it can be pretty durable under a wide range of conditions.

What is your "altitude used" ?

Let me quess: You have not decided it.

SR-71 was flying at much lower speeds, at very high altitudes, and it needed titanium  for critical parts of the airframe to survive the heat from the drag.

[Jim]

The thinness of the atmosphere at the altitudes used, along with choice of cable material to let it handle the heating that it does encounter. My guess is that some type of steel may be the best choice, since it can be pretty durable under a wide range of conditions.

Can't have both a thin atmosphere to reduce heating yet be thick enough to support flight.   
There isn't going to be a cable that can survive the heating.

This is where you don't understand "flight'.  Unpowered flight (gliding) does not occur over 33km or so.  The shuttle is falling.

[Archibald]

This thread has some of the same nonsense.  It was shown that it is not feasible to work for some of the same reasons.

https://forum.nasaspaceflight.com/index.php?topic=41207.0

This thread also had a lot of trolling by a certain member (mansol )

[IsaacKuo]

So what is protecting the cable from aeroheating at 2km/sec?

The thinness of the atmosphere at the altitudes used, along with choice of cable material to let it handle the heating that it does encounter. My guess is that some type of steel may be the best choice, since it can be pretty durable under a wide range of conditions.

What is your "altitude used" ?

Let me quess: You have not decided it.

SR-71 was flying at much lower speeds, at very high altitudes, and it needed titanium  for critical parts of the airframe to survive the heat from the drag.

I don't know the exact altitude appropriate, but it would be something in the range of X-15 flight. The SR-71 was designed for sustained level flight, not short term ballistic flight like the X-15. You use lift for maneuvering while braking, not for level flight while sustaining speed.

In this regime, the Space Shuttle Orbiter has a lift:drag glide ratio of around 1:1. This sounds horrible, but it's actually just fine. You are trading speed for turning, which is a familiar concept for anyone familiar with air combat maneuvering - turning bleeds speed like crazy. But here's the point--it can be done and it has been demonstrated in real life. Hypersonic reentry research vehicles have done hairpin turns. That doesn't imply doing a hairpin turn while maintaining constant speed. No, a hairpin turn bleeds away a lot of speed.

But we want to bleed away a lot of speed - and quickly! The more quickly the speed is bled, the shorter the exposure to heating. Most of this heating will be experienced by the wings, since they have the largest area.

So, we do one or more S turns to bleed away speed and maneuver to the desired position and velocity to meet L-SSTO. At the end of this, we do a final upward turn to direct our velocity vector on a 15 degree upward angle. This puts us on a ballistic path into thinner air, going upward at around 600m/s. That's around one scale height every ten seconds. So drag is halved every ten seconds. So I can't really say exactly how much drag and heating the cable will suffer when it's deployed, but it can be halved by waiting another ten seconds.

Roughly speaking, the total drag and heating will be about twice that of the first ten seconds (1+1/2+1/4+1/8+... = 2). This is just a rough approximation, since gravity will halt upward velocity in a minute (there's another minute before falling to the original altitude). But it gives an idea of the order of magnitude.

For the second encounter, the initial upward velocity is much greater. At 4km/s, a final upward turn of 15 degrees implies an upward velocity of around 1200m/s. That's about a scale height every five seconds, and it will continue upward for two minutes (with another two minutes before falling back to the original altitude).

[IsaacKuo]

I don't really have the inclination to argue with someone who doesn't think it's possible to pitch upward with an aircraft, braking while changing the heading to 15 degree upward (thus entering an upward ballistic trajectory).

Mid-air refueling is a thing that actually happens.

Supersonic or hypersonic mid-air-refueling does not happen. Refueling is currently only performed on subsonic speeds, AND it's only performed when both aircrafts are under thrust.

There are particular practical reasons why refueling is only done under those conditions, but they are not relevant to the control problem of aligning the two vehicles with great precision.

Controlled gliding from orbit to a specific altitude and position actually happens.

.. with huge wings, when this specific altitude is 0 so that there is LOTS OF TIME to do the manouvering.

The spacecraft considered here have huge wings. And not all reentry vehicles are designed to take a long time to reach the ground. While it massively increases the TPS requirements, military ballistic missiles are designed to reach the target quickly to better penetrate enemy defenses. Maneuvering is also used to help penetrate enemy defenses.

Trying to rendeznous something running at hypersonic speed is totally different thing than landing into stationary runway.

As far as the control system is concerned, it really isn't that different. You've got particular coordinates in space-time that you're trying to reach. In this case, the virtual runway coordinates are moving like a very fast aircraft carrier, at the desired rendezvous. It's fundamentally like trying to land on a runway with an extremely fast headwind.

You are messing up completely different things. Much easier things are done and you are using this as a claim that much harder things can be done.

I'm not the one who claimed that mid-air towing for the final vehicle is impossible because sometimes mid-air refueling hookups don't work. That's for the easiest hookup by far - the one where the returning R-SSTO is hooking up with the F15 for final towing back toward home base. In this much slower regime, the glide ratio is much better and the forward speed much lower, so the descent rate is not so bad. The F15 jet can fly ahead of the R-SSTO all the way down without breaking a sweat. It's not like those helicopter attempts to capture a parachuting payload where it's hard or impossible to get more than one attempt. This jet can fly parallel to this glider the whole way down.

[hkultala]

It's fundamentally like trying to land on a runway with an extremely fast headwind.

Nobody is/has been landing an (orbital) glider into very fast headwind.

Shuttle had tight weather requirements for landing.

[hkultala]

I don't really have the inclination to argue with someone who doesn't think it's possible to pitch upward with an aircraft, braking while changing the heading to 15 degree upward (thus entering an upward ballistic trajectory).

Mid-air refueling is a thing that actually happens.

Supersonic or hypersonic mid-air-refueling does not happen. Refueling is currently only performed on subsonic speeds, AND it's only performed when both aircrafts are under thrust.

There are particular practical reasons why refueling is only done under those conditions, but they are not relevant to the control problem of aligning the two vehicles with great precision.

Yes they are. Things like shock wave of the first aircraft affects the control of the second aircraft

[Archibald]

This thread has some of the same nonsense.  It was shown that it is not feasible to work for some of the same reasons.

https://forum.nasaspaceflight.com/index.php?topic=41207.0

Once you desorbit (below 7.2 km/s) , there is no (easy) way back into orbit, even for a stage crammed with propellant.

I often wonder if the NRO ever tried brief desorbit / re-orbit of their Agena-based Key Holes, for better resolution ? How low could a satellite "dive" before kamikazing into the atmosphere ?

[Jim]

1.  I don't know the exact altitude appropriate, but it would be something in the range of X-15 flight. The SR-71 was designed for sustained level flight, not short term ballistic flight like the X-15.

2.  You use lift for maneuvering while braking, not for level flight while sustaining speed.

3.  In this regime, the Space Shuttle Orbiter has a lift:drag glide ratio of around 1:1. This sounds horrible, but it's actually just fine. You are trading speed for turning, which is a familiar concept for anyone familiar with air combat maneuvering - turning bleeds speed like crazy. But here's the point--it can be done and it has been demonstrated in real life. Hypersonic reentry research vehicles have done hairpin turns. That doesn't imply doing a hairpin turn while maintaining constant speed. No, a hairpin turn bleeds away a lot of speed.

4.  But we want to bleed away a lot of speed - and quickly! The more quickly the speed is bled, the shorter the exposure to heating. Most of this heating will be experienced by the wings, since they have the largest area.

5.  So, we do one or more S turns to bleed away speed and maneuver to the desired position and velocity to meet L-SSTO. At the end of this, we do a final upward turn to direct our velocity vector on a 15 degree upward angle

This post is bereft of reality

1. Non plausible.   at X-15 highest altitudes, reaction control was needed.  At the its lowest altitudes, 2km/sec would have too much heating.

2. Wrong.  No, lift was used for braking.  The shuttle used reaction control  for maneuvering.  In fact, some thrusters were used down to 50kft. 

3.  Proof please.  a 180 degree turn does not equate to "hairpin"

4 And the intensity of the heating is greater.  What TPS is going to be used?

5.  wrong.  Climbing is not possible.

[Jim]

I don't really have the inclination to argue with someone who doesn't think it's possible to pitch upward with an aircraft, braking while changing the heading to 15 degree upward (thus entering an upward ballistic trajectory).

Mid-air refueling is a thing that actually happens.

Supersonic or hypersonic mid-air-refueling does not happen. Refueling is currently only performed on subsonic speeds, AND it's only performed when both aircrafts are under thrust.

There are particular practical reasons why refueling is only done under those conditions, but they are not relevant to the control problem of aligning the two vehicles with great precision.

Yes they are. Things like shock wave of the first aircraft affects the control of the second aircraft

And since this is supposedly done at 2km/sec, the shock wave is huge and there is a ionization sheath.  There will be no visibility.

[Archibald]

There were talk in the aerospaceplane days of hypersonic refueling to be tested by a pair of X-15s. the idea was rightly discarded before flight testing began... while X-15 suborbital flights were rather begnin, hypersonic records took a toll on the structure, with the scramjet mockup standing on the way of the hypersonic flow.

[Vultur]

I have to say this seems overly complex to be economical.

1. Non plausible.   at X-15 highest altitudes, reaction control was needed.  At the its lowest altitudes, 2km/sec would have too much heating.

Sure, but the max altitude flights of X-15 were not the max speed flights. The speed record of X-15 (which was around 2 km/s, 4520 mph) was set at "only" ~31km.

[CameronD]

There were talk in the aerospaceplane days of hypersonic refueling to be tested by a pair of X-15s. the idea was rightly discarded before flight testing began... while X-15 suborbital flights were rather begnin, hypersonic records took a toll on the structure, with the scramjet mockup standing on the way of the hypersonic flow.

{emphasis mine} I think Michael J. Adams (and others in ground control) would disagree with you.

https://en.wikipedia.org/wiki/X-15_Flight_3-65-97

 

[Katana]

There were talk in the aerospaceplane days of hypersonic refueling to be tested by a pair of X-15s. the idea was rightly discarded before flight testing began... while X-15 suborbital flights were rather begnin, hypersonic records took a toll on the structure, with the scramjet mockup standing on the way of the hypersonic flow.

{emphasis mine} I think Michael J. Adams (and others in ground control) would disagree with you.

https://en.wikipedia.org/wiki/X-15_Flight_3-65-97

And the SR71 / D21 air launch collision