Author Topic: RLVs and the quest for "airline-like operations"  (Read 9779 times)

Offline Archibald

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Re: RLVs and the quest for "airline-like operations"
« Reply #40 on: 06/01/2018 11:44 AM »
90% of the worlds people live within 300 miles of an ocean.  So, first spaceports for large spaceships will probably be slightly offshore of large cities.  Like the SpaceX video, maybe something like an oil rig for the large spaceship and boosters.  There are a lot of large cities in most countries on their coasts.  Most passengers going to space designations in the future will probably fly or take a high speed train or hyperloop to the spaceports, then go to their destinations in space.  Due to the need for water to break the noise of a rocket launch, there may be spaceports in the Great lakes or interior lakes of Russia. 

Moscow and Beijing strongly disagree with that statement. Bad luck, China and Russia are two major powers on that planet.

Quote
Depends on the details (which as usual were fairly limited). IIRC deep ocean oil rigs are not always anchored to the sea bed and ride out storms.  Compared to an oil rig in say the North Sea BFR is not that big.
OTOH the pad to handle the landing uncertainty is much bigger, as is the the height of the access tower.   Both of which could definitely be problems, in essence due to the very large aspect ratios involved.

And tornadoes aren't just a Florida, or even a Caribbean thing. They've even damaged coastal towns in England (yes, actual spinning columns of air and water) and as far inland as Birmingham.  :(

Good point here. While F5 tornadoes are rare (fortunately) continental europe certainly has F1 and F2 on a regular basis, plus waterspouts,
and also those freakkin' things - 150 mph gusts.
https://en.wikipedia.org/wiki/European_windstorm
I live in a corner of France that endured the 1999 and 2009 windstorms (Klaus, Lothar and Martin), and damage was appaling both times.
« Last Edit: 06/01/2018 11:51 AM by Archibald »
...you have been found guilty by the elders of the forum of a (imaginary) vendetta against Saint Elon - BLAAASPHEMER !

Offline john smith 19

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Re: RLVs and the quest for "airline-like operations"
« Reply #41 on: 06/02/2018 11:58 AM »
Quote
Depends on the details (which as usual were fairly limited). IIRC deep ocean oil rigs are not always anchored to the sea bed and ride out storms.  Compared to an oil rig in say the North Sea BFR is not that big.
OTOH the pad to handle the landing uncertainty is much bigger, as is the the height of the access tower.   Both of which could definitely be problems, in essence due to the very large aspect ratios involved.

And tornadoes aren't just a Florida, or even a Caribbean thing. They've even damaged coastal towns in England (yes, actual spinning columns of air and water) and as far inland as Birmingham.  :(

Good point here. While F5 tornadoes are rare (fortunately) continental europe certainly has F1 and F2 on a regular basis, plus waterspouts,
and also those freakkin' things - 150 mph gusts.
https://en.wikipedia.org/wiki/European_windstorm
I live in a corner of France that endured the 1999 and 2009 windstorms (Klaus, Lothar and Martin), and damage was appaling both times.
WRT to the thread title I think it comes down to 2 issues.
1) For any phase of the flight how long is the vehicle exposed
2)What are the consequences of a mishap during that phase.

RLV's operate over a much wider range of both speeds and altitudes than any other, except ELV's.

IIRC Weather was the second worst problem for Shuttle launch delays. Critical issues were
1) Without being certified for instrument flying the Shuttle needed near perfect weather over the Cape and all alternate landing sites
2) High altitude winds could delay/scrub a launch. Shuttle had no air data system so launch trajectory was pre planned and pre loaded (presumably in part because the SRB could not be throttled and generated 90% of the T/O thrust). This improved with DoLILU, redesigning the program with data no more than 2 hours before the time of launch.

This suggests that either you should avoid big solids or make them throttleable if you want more ALO.
It also suggests any winged stage should be certified for instrument flying (although that should be automatic if it's not crewed to begin with).

Obviously while aircraft execute a more or less standard takeoff (in terms of engine power levels, flaps, take off angle etc) those values are not hardwired into the autopilot (all Shuttle takeoffs were automated, unless something serious happened to a GNC).
So "More ALO" in this context means, "Collect air data on the way up and throttle and adjust launch angle accordingly."
Keep in mind the pre planned trajectory table dates from the days with on board computers ran 10s of Instructions per Second.
A modern processor is perfectly capable of handling the guidance task at 400MIPs and dropping its clock rate once out of the sensible atmosphere.


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Offline Katana

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Re: RLVs and the quest for "airline-like operations"
« Reply #42 on: 06/04/2018 09:18 PM »
90% of the worlds people live within 300 miles of an ocean.  So, first spaceports for large spaceships will probably be slightly offshore of large cities.  Like the SpaceX video, maybe something like an oil rig for the large spaceship and boosters.  There are a lot of large cities in most countries on their coasts.  Most passengers going to space designations in the future will probably fly or take a high speed train or hyperloop to the spaceports, then go to their destinations in space.  Due to the need for water to break the noise of a rocket launch, there may be spaceports in the Great lakes or interior lakes of Russia. 

Moscow and Beijing strongly disagree with that statement. Bad luck, China and Russia are two major powers on that planet.

Exclude them and go Europe / Japan, or think out of the box.

Suborbital transport to Russia = economical and maybe political no go.
Suborbital transport to China (SX video) = ITAR no go. Even if you land on sea 12 miles off shore Shanghai.

But, suborbital military "transport" to them may worth magnitudes more profit.

F35 or B2 vs Boeing 787 vs Concorde, on profit.

It's not civil, but spaceflight is nowhere really civil.
ITAR = International terms on ARMS regulations. Everything controlled are called the US AMMUNITION list.

Offline su27k

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Re: RLVs and the quest for "airline-like operations"
« Reply #43 on: 06/05/2018 03:04 AM »
90% of the worlds people live within 300 miles of an ocean.  So, first spaceports for large spaceships will probably be slightly offshore of large cities.  Like the SpaceX video, maybe something like an oil rig for the large spaceship and boosters.  There are a lot of large cities in most countries on their coasts.  Most passengers going to space designations in the future will probably fly or take a high speed train or hyperloop to the spaceports, then go to their destinations in space.  Due to the need for water to break the noise of a rocket launch, there may be spaceports in the Great lakes or interior lakes of Russia. 

Moscow and Beijing strongly disagree with that statement. Bad luck, China and Russia are two major powers on that planet.

Exclude them and go Europe / Japan, or think out of the box.

There're not many passengers going to Russia anyway, even mainland China is not in the top 15 routes by ASKs presented in this article: http://thespacereview.com/article/3492/1

Offline Katana

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Re: RLVs and the quest for "airline-like operations"
« Reply #44 on: 06/05/2018 04:41 AM »
- does space transportation to orbit needs such an extensive network of spaceports - in term of passengers and flight frequency ? Air transportation carried 4 billion passengers annually (for the sake of comparison)
Quite true.
So what features of aircraft facilitate that volume and which of them (if any) can a space LV duplicate?

A "space LV" need not duplicate any of them.  Going back to the question:  Airbus invested large amounts of money in the A380 concept, because it was seen (at the time) to be more cost-effective(, fuel-efficient, whatever) to deliver international passengers to one or two major international "hubs" in each country/region via domestic services and then shove them all in the one aircraft for delivery overseas.  The airports initially chosen a decade or so ago to become "international hubs" were then upgraded to take A380's and included the likes of Sydney, Heathrow, Frankfurt, LA, Dubai, Singapore, Hong Kong to name a few.  To upgrade a airport to take the A380 was no small task and involved lengthening and strengthening runways, altering passenger terminals to park the aircraft, installing new aerobridges and upgrades to the fuel system.   The idea worked quite well for a while, but eventually a bunch of minor airports got in the act and other. smaller, long-range aircraft were developed (eg Dreamliner) that didn't need quite so much infrastructure and it faded to the organised chaos we have today.

Using the same model, all you need to start with is one or two "spaceports" close to, or associated with, a regional airport.  Then, instead of travelling from their local town to LAX to fly to Sydney (for example) you might travel to Spaceport America and land somewhere in the Outback.  Stick to that because, for many reasons discussed here and elsewhere, a space LV system is never going to be able to compete with sub-sonic low-cost airlines for the regional transport market - but international travel is something else entirely.
The hub mode would cost additional 1~3 hours, full trip durarion 2~4 hours.

A M3~4 version of Concorde (with take off and landing in subsonic mode) could also finish the same trip in 4~5 hours.

Suborbital transport is only marginally faster for passenger over aircraft.

Offline Katana

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Re: RLVs and the quest for "airline-like operations"
« Reply #45 on: 06/05/2018 04:57 AM »
As said in the tin (and also on that other thread)

Since 1958 the line of fracture among RLV supporters and designers can be summarized as
"Shall we turn aircrafts into rockets, or rockets into aircrafts ?"

the holy grail has alway been "we need airlines to space". Typical of that thinking: Clarke, 2001, and Orion III in PanAm livery.

It worked well in fiction, but reality has been more *cruel*.

---

TWO EXAMPLES of this trend .

Musk point-to-point BFR try to cheat that paradigm in a rather clever way. Put the BFR on a large floating platform, far enough from the cost rocket noise and range safety are no issues. Bring the passengers with fast boats.
Of course that doesn't solve other issues, such as landing noise, sonic booms, and of course - lift off and landings from towns far away from the sea such as Moscow. But overall, a nice try, Elon.

---

My personal pet concept is to build a rocket plane with a single GE-90, which is perfectly welcome at airports (noise, pollution: check).
Then light the rocket at high altitude and fly into orbit. Makes no mistake: propellant mass fraction and overall mass fraction would be horrible, even more with the huge mass of the GE-90.

The trick is to use suborbital refueling, through an identical rocket plane. Flyy as fast and high as a 85% mass fraction (not SSTO 95%) permits, then goes into a suborbital parabola (3 to 5 minutes, no more) and refuel briefly - 40 000 or 50 000 pounds of propellants, just enough to reach a low, stable orbit.

I previously discussed this concept on this forum and I do know it is controversial. On paper it works, but the devil is in the details (gravity losses, for a start !)

This thread is not to discuss that concept.

Different destination are different animal, though they may look similar and share some concepts.

"Aircraft like" routine operation to orbit: BFR

"Rocket like" fast P2P ground transport: SabreSkylon, or new Boeing 2707 with modified GE90.


Offline john smith 19

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Re: RLVs and the quest for "airline-like operations"
« Reply #46 on: 06/06/2018 10:15 PM »
Different destination are different animal, though they may look similar and share some concepts.

"Aircraft like" routine operation to orbit: BFR
In what sense. All evidence is that as a TSTO it will be considerably harder to prep for re-launch than any single stage vehicle.
Quote from: Katana
"Rocket like" fast P2P ground transport: SabreSkylon, or new Boeing 2707 with modified GE90.
You seem to have this backward. SABRESkylon is for orbital launch, but a SABRE engined aircraft can manage up to M5. As for the idea of a "Boeing 2707" IIRC it was engined by turboramjets.  The odds on bet is the blades on the GE90 will melt somewhere above M1. An aircraft (and the original 2707 was only an aircraft) would (surprise surprise) be capable of "aircraft like" operations by design, as would a SABRE engineed aircraft.

Perhaps you should think a bit more about what you're trying say, since what you've written does not make much sense.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Katana

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Re: RLVs and the quest for "airline-like operations"
« Reply #47 on: 06/06/2018 10:52 PM »
Different destination are different animal, though they may look similar and share some concepts.

"Aircraft like" routine operation to orbit: BFR
In what sense. All evidence is that as a TSTO it will be considerably harder to prep for re-launch than any single stage vehicle.
Quote from: Katana
"Rocket like" fast P2P ground transport: SabreSkylon, or new Boeing 2707 with modified GE90.
You seem to have this backward. SABRESkylon is for orbital launch, but a SABRE engined aircraft can manage up to M5. As for the idea of a "Boeing 2707" IIRC it was engined by turboramjets.  The odds on bet is the blades on the GE90 will melt somewhere above M1. An aircraft (and the original 2707 was only an aircraft) would (surprise surprise) be capable of "aircraft like" operations by design, as would a SABRE engineed aircraft.

Perhaps you should think a bit more about what you're trying say, since what you've written does not make much sense.

Precisely and simply: BFR for orbit and beyond with more than one flight per week per vehicle, fan burning turboramjet M2.5~3.5 or Scimitar M5 aircraft for daily travel on earth.

However all fancy words familiar to this thread got lost on the latter half sentence. The title of this thread is "a piece of s***" like.

Note: MIG31 reach M2.8 with D30F6 turbofan, which is a fan burning mod of D30KP on Tu-154 airliner.

MIG25 have methanol injection into inlet. Better if REL could invent a methane Scimitar, LH2 aircraft sucks.
« Last Edit: 06/06/2018 11:03 PM by Katana »

Offline Jim

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Re: RLVs and the quest for "airline-like operations"
« Reply #48 on: 06/07/2018 01:38 PM »

IIRC Weather was the second worst problem for Shuttle launch delays. Critical issues were
1) Without being certified for instrument flying the Shuttle needed near perfect weather over the Cape and all alternate landing sites
2) High altitude winds could delay/scrub a launch. Shuttle had no air data system so launch trajectory was pre planned and pre loaded (presumably in part because the SRB could not be throttled and generated 90% of the T/O thrust). This improved with DoLILU, redesigning the program with data no more than 2 hours before the time of launch.


Jeesh, where do you come up with this stuff.

1.  It had nothing to do with being "certified for instrument flying".  Most of the entry is done on instruments.  The orbiter was more instrumented than "certified" aircraft. 
a.  The main reason was moisture in the clouds
b.  NASA wanted visual cues since there was no go around capability.

2.  No again. 
a.  No launch vehicle uses air data
b.  It has nothing to with SRB throttle capability
c.  It is a wind shear issue, and all launch vehicles are affected by it.   All launch vehicle trajectories are preplanned and all use some sort of DoLILU.

Offline john smith 19

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Re: RLVs and the quest for "airline-like operations"
« Reply #49 on: 06/07/2018 06:23 PM »
Precisely and simply: BFR for orbit and beyond with more than one flight per week per vehicle, fan burning turboramjet M2.5~3.5 or Scimitar M5 aircraft for daily travel on earth.

However all fancy words familiar to this thread got lost on the latter half sentence. The title of this thread is "a piece of s***" like.
Compared to aircraft all ELV's are poor.  Concorde managed multiple  daily "launches" without passengers being in pressure suits, or needing ejector seats, while in super cruise.
BTW LAPCAT A2 SCIMATAR was toward the slow end of what the EU programme wanted. However only it and the DLR's Kerosene SCramjet concept got to the follow on programme. DLR claimed M8 cruise was possible but their could not meet the range at the stated permissible take off weight. 

Quote from: Katana
Note: MIG31 reach M2.8 with D30F6 turbofan, which is a fan burning mod of D30KP on Tu-154 airliner.

MIG25 have methanol injection into inlet.
I know Wikipedia entries are not always reliable but the listed T/W ratio of the engine (3.8) is worse than the J58 at the core of the SR71's engine nacelle (about 5.5 dry, half that when inside the nacelle).

Quote from: Katana
Better if REL could invent a methane Scimitar, LH2 aircraft sucks.
If what you're trying to do is hard (and both fully reusable RLV and M5 cruise are hard) it's logical you look for every advantage possible, starting with the highest performing fuel.

If you can't make it work with that, what makes you think it can work with anything less?

It was lack of Isp that Musk claimed (MIT presentation in 2014) stopped F9 (and any vehicle based on it) from permitting US reuse with an economic payload.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline john smith 19

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Re: RLVs and the quest for "airline-like operations"
« Reply #50 on: 06/07/2018 07:26 PM »

1.  It had nothing to do with being "certified for instrument flying".  Most of the entry is done on instruments.  The orbiter was more instrumented than "certified" aircraft. 
a.  The main reason was moisture in the clouds
b.  NASA wanted visual cues since there was no go around capability.
Which comes down to Shuttle being VFR rated only.  Different words, same result.  :(

The problems with this are a) AIUI you need all runways to have near perfect visibility for the landing. That is much more restrictive than a conventional aircraft, but then you have no go round capability.
I've always wondered about how much damage a landing through clouds would do to the Shuttles TPS.
Sure, landing in a hail storm would be bad (as it's bad for all passenger aircraft) but what's the lower limit? What could it have flown through?

I notice you have not contradicted that weather was the 2nd major cause of Shuttle scrubs.
Quote from: Jim
2.  No again. 
a.  No launch vehicle uses air data
b.  It has nothing to with SRB throttle capability
c.  It is a wind shear issue, and all launch vehicles are affected by it.   All launch vehicle trajectories are preplanned and all use some sort of DoLILU.
I'm aware no current vehicle does. The question is wheather (if you want to do actual consistent regular airline style ops) you should. I was also thinking of the very low limit on cross winds during landing that Shuttle had.   
High altitude winds are another thing (like coupled loads analysis) that no normal aircraft has to worry about. The obvious question is wheather a vehicle can be built that doesn't need to worry about them or wheather a design can be built that can adjust sufficiently in flight to avoid structural failure.

Which I guess is kind of one of the themes of this thread.

As I've said before I think Shuttle was designed and built as well as possible given its funding, design constraints and stakeholder group. It has provided a treasure trove of information on semi RLV operations.

But I do believe we can do better today.
« Last Edit: 06/08/2018 06:01 AM by john smith 19 »
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline CameronD

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Re: RLVs and the quest for "airline-like operations"
« Reply #51 on: 06/07/2018 11:35 PM »
2.  No again. 
a.  No launch vehicle uses air data
b.  It has nothing to with SRB throttle capability
c.  It is a wind shear issue, and all launch vehicles are affected by it.   All launch vehicle trajectories are preplanned and all use some sort of DoLILU.
I'm aware no current vehicle does. The question is wheather (if you want to do actual consistent regular airline ops you should). I was also thinking of the very low limit on cross winds during landing that Shuttle had.   
High altitude winds are another thing (like coupled loads analysis) that no normal aircraft has to worry about. The obvious question is wheather a vehicle can be built that doesn't need to worry about them or wheather a design can be built that can adjust sufficiently in flight to avoid structural failure.

The very low limit on cross winds during landing was because, as Jim said, the Shuttle had no go-around capability (..and AIUI poor aerodynamic control at landing speed also).

Wind shear is potentially an issue for *any* vehicle flying at speed through the atmosphere - from a drone to an RLV.  The faster you go the bigger the problem and to build a hypersonic vehicle strong enough to "not worry about" it most likely means it'd be so over-engineered it would never lift off the ground.  It's far better, for the comfort of all involved (both on the ground and in the air), to, as much as is practically possible, plan the trajectory beforehand.  Airlines do it.  So do LVs.

As I've said before I think Shuttle was designed and built as well as possible given its funding, design constraints and stakeholder group....

Gee, I hope not.  Shuttle has been described by at least one astronaut who flew it (and therefore should know) as "a butterfly strapped to a bullet!"  Case in point.
« Last Edit: 06/08/2018 03:56 AM by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline john smith 19

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Re: RLVs and the quest for "airline-like operations"
« Reply #52 on: 06/08/2018 06:18 AM »
The very low limit on cross winds during landing was because, as Jim said, the Shuttle had no go-around capability (..and AIUI poor aerodynamic control at landing speed also).

Wind shear is potentially an issue for *any* vehicle flying at speed through the atmosphere - from a drone to an RLV.  The faster you go the bigger the problem and to build a hypersonic vehicle strong enough to "not worry about" it most likely means it'd be so over-engineered it would never lift off the ground.  It's far better, for the comfort of all involved (both on the ground and in the air), to, as much as is practically possible, plan the trajectory beforehand.  Airlines do it.  So do LVs.
You're not talking about the same things.

What Jim and I are talking about are high altitude winds which IIRC are 80 Kft+. This is not the sudden shift in lift characteristics of an aircraft, since by this point Shuttle was not relying on aerodynamic lift.

In principle all gliders are vulnerable to wind shear. I'd like to find out what the limits on the X37b, or Buran were.

But landing cross winds were also a limitation. I'm guessing the slab sides (what other aircraft has them?) didn't help much either.

WRT to the title, what proportion of landings (or take offs) get scrapped due to wind shear? Does VTOL make it easier or worse? Is it really about powered go around, or more a question of fast enough acting flight controls, and being able to detect (and react) to it far enough ahead?
Quote from: CameronD
As I've said before I think Shuttle was designed and built as well as possible given its funding, design constraints and stakeholder group....

Gee, I hope not.  Shuttle has been described by at least one astronaut who flew it (and therefore should know) as "a butterfly strapped to a bullet!"  Case in point.
There are various roller coasters where you can pull 3g. OTOH they are not powered by SRB's, Solids give notoriously hard rides to payloads. Lots of vibrations. But (supposedly) cheap to design and make and (being solid) immune to "Pogo" vibration in the fuel system (because there isn't one).

I'd suggest the Astronaughts were not that a strong stakeholder group, while the US taxpayer wasn't even  on the list.  :(
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline CameronD

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Re: RLVs and the quest for "airline-like operations"
« Reply #53 on: 06/08/2018 07:44 AM »
WRT to the title, what proportion of landings (or take offs) get scrapped due to wind shear? Does VTOL make it easier or worse? Is it really about powered go around, or more a question of fast enough acting flight controls, and being able to detect (and react) to it far enough ahead?

You mean airlines?  I doubt very many airline takeoffs and landings get scrapped due to wind shear, mainly because (a) the worst wind shear occurs in clouds and, for a few reasons, airlines don't generally approve of an aircraft landing if the pilots can't visually see the runway and (b) the airplane is travelling at relatively low speed on takeoff and landing.  OTOH, turbulence is another problem entirely!

Does VTOL make it worse?  Good question.  As I posted before, wind shear is potentially an issue for any vehicle flying at speed through the atmosphere.  The slower you go, the less the problem.. although IIRC numerous rocket launches are called off because of the risk of flying through cloud, so the answer is most probably, yes - but only at altitude, not near the ground.   

..but the solution to wind shear concerns is, in most cases is quite simple:  Don't fly/launch in/through cloud - especially nasty-looking clouds.. and, funnily enough, that's exactly what aero folks try to do. :)
   
« Last Edit: 06/08/2018 08:17 AM by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

Offline spacenut

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Re: RLVs and the quest for "airline-like operations"
« Reply #54 on: 06/08/2018 12:22 PM »
It is a fact that 90% of the worlds people live within 300 miles of an ocean or sea.  World maritime trade caused this years ago.  This is why America's aircraft carriers are such a powerful force.  Russia only has 140 million people with limited access to the sea.  Even most of China's population is within 300 miles of their coast.  Interior is mountains or desserts.  They would probably have coastal slightly off shore launch facilities off Shanghai or Hong Kong.  Russia is the one power that would have the most problem with a large rocket launching and landing.  Central Asia would probably be their best location or the Caspian or Black seas. 

Oh, another thing, over 80% of the people in the world that have flown in an airliner are Americans.  Most Europeans and Chinese use their rail system.  Americans fly around the country and do not use trains as much.  I don't see massive use of rocket travel.  Concorde didn't pan out well.  Too expensive for most passengers so they took traditional sub-sonic flights.  Maybe in 50 years or longer. 
« Last Edit: 06/08/2018 12:28 PM by spacenut »

Offline john smith 19

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Re: RLVs and the quest for "airline-like operations"
« Reply #55 on: 06/09/2018 08:09 AM »
You mean airlines?  I doubt very many airline takeoffs and landings get scrapped due to wind shear, mainly because (a) the worst wind shear occurs in clouds and, for a few reasons, airlines don't generally approve of an aircraft landing if the pilots can't visually see the runway and (b) the airplane is travelling at relatively low speed on takeoff and landing.  OTOH, turbulence is another problem entirely!
So how do aircraft land in smog in Chinese cities? Depending on the aircraft autoland has been available since 1968 with no pilot's hands on the stick or throttle.
Quote from: CameronD
Does VTOL make it worse?  Good question.  As I posted before, wind shear is potentially an issue for any vehicle flying at speed through the atmosphere.  The slower you go, the less the problem.. although IIRC numerous rocket launches are called off because of the risk of flying through cloud, so the answer is most probably, yes - but only at altitude, not near the ground.   

..but the solution to wind shear concerns is, in most cases is quite simple:  Don't fly/launch in/through cloud - especially nasty-looking clouds.. and, funnily enough, that's exactly what aero folks try to do. :)
 
This nicely demonstrates that actually the idea of ALO has 2 problems to face.
1) LV faces conditions that normal aircraft don't.
2) The way they have historically been controlled in ascent (pre planned thrust/attitude programs developed possibly months in advance, DoLILU brought this down to a few hours) don't allow they to do things like avoid flying through a cloud, if it's right in their path.

This sort of stuff is rarely considered by the "armchair" rocket engineer but it's critical if people want to do this IRL.  :(

It needs to be considered from day one of a design as it's likely to be very difficult to retrofit.



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Offline Archibald

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Re: RLVs and the quest for "airline-like operations"
« Reply #56 on: 06/09/2018 08:13 AM »
some random examples from the top of my head
- In 1969 a giant Saturn V was hit by lightning, yet made it through.
- By contrast, in april 1987, a much smaller Atlas was hit, too, and had to be destroyed.
- In June 2012 President François Hollande Airbus was hit by lightning, but aircrafts are designed to handle such things, and it just shrugged it off and kept flying without a glitch.

In Toulouse the CEAT has a peculiar test stand where they simulate lightning and hit every single military and civilian prototypes as part of the certification process. Shall we test RLVs this way ?
« Last Edit: 06/09/2018 08:18 AM by Archibald »
...you have been found guilty by the elders of the forum of a (imaginary) vendetta against Saint Elon - BLAAASPHEMER !

Offline john smith 19

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Re: RLVs and the quest for "airline-like operations"
« Reply #57 on: 06/09/2018 10:19 AM »
some random examples from the top of my head
- In 1969 a giant Saturn V was hit by lightning, yet made it through.
- By contrast, in april 1987, a much smaller Atlas was hit, too, and had to be destroyed.
- In June 2012 President François Hollande Airbus was hit by lightning, but aircrafts are designed to handle such things, and it just shrugged it off and kept flying without a glitch.

In Toulouse the CEAT has a peculiar test stand where they simulate lightning and hit every single military and civilian prototypes as part of the certification process. Shall we test RLVs this way ?
IIRC  the Saturn was running a backup copy of the flight guidance on an Apollo Guidance Computer which took over. IOW the computer was on a payload. Since this was not happening with the Atlas, range safety destroyed it.

For ALO schedule becomes much more important. Likewise not being bumped off a flight because NASA payloads took priority over 3rd parties is an issue. This plagued Douglas's attempts to develop commercial, on orbit electrophoresis for drug extraction, mostly negating the benefits of being able to study (and modify) flight hardware in the wake of test results.

Lightning strikes are definitely an issue. Airlines don't stop for them.  With relatively little history of RLV landings to go on (Buran was 1 flight, X37b has a vew, Shuttle about 135) it's harder to say what can be dealt with and how.
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Offline Jim

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Re: RLVs and the quest for "airline-like operations"
« Reply #58 on: 06/09/2018 02:18 PM »
IIRC  the Saturn was running a backup copy of the flight guidance on an Apollo Guidance Computer which took over. IOW the computer was on a payload. Since this was not happening with the Atlas, range safety destroyed it.


No, the Saturn launch vehicle guidance system was unaffected by the strike.  The spacecraft avionics, including the AGC, were knocked offline by the surge.

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Re: RLVs and the quest for "airline-like operations"
« Reply #59 on: 06/09/2018 02:22 PM »
2) The way they have historically been controlled in ascent (pre planned thrust/attitude programs developed possibly months in advance, DoLILU brought this down to a few hours) don't allow they to do things like avoid flying through a cloud, if it's right in their path.

They still are developed months in advance.  DoLILU, which has been available in most vehicles since the '70s, only provides for adjustments for winds in the first 100k ft.  The trajectory is basically the same. 

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