Author Topic: The Reaction Engines Skylon Master Thread (1)  (Read 746158 times)

Offline Warren Platts

Re: The Reaction Engines Skylon Master Thread
« Reply #1080 on: 10/28/2012 07:44 pm »
Quote from: baldusi
I seriously doubt that it will be able to even take off with such a low air pressure.

That would be a great question for Mr. Hempsell if he ever comes back!

I don't see how the altitude at Quito would be a showstopper. The current airport there is one of the busiest commercial airports in South America. So you have to build an extra long runway. What's the big deal with that? As for air frames cracking, just make sure the runway is made of high-quality, extra smooth pavement.

If they can get the cost per flight down to $5M/ea. that would be great, but even so, a 3% savings is $150,000 per flight. If they're flying every day (and at $333/kg it seems like they would have to), that adds up to $54M/year--not exactly chump change.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline Carreidas 160

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Re: The Reaction Engines Skylon Master Thread
« Reply #1081 on: 10/28/2012 08:43 pm »
Quote from: baldusi
I seriously doubt that it will be able to even take off with such a low air pressure.

That would be a great question for Mr. Hempsell if he ever comes back!

I don't see how the altitude at Quito would be a showstopper. The current airport there is one of the busiest commercial airports in South America. So you have to build an extra long runway. What's the big deal with that? As for air frames cracking, just make sure the runway is made of high-quality, extra smooth pavement.

In commercial aviation, launching at higher altitudes seriously decreases the max takeoff weight and thus range/payload. I doubt this will be different from Skylon. Better to launch from, say, KSC and lose 50m/s delta-V, while enjoying a better logistics supply chain.

Offline Jim

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Re: The Reaction Engines Skylon Master Thread
« Reply #1082 on: 10/28/2012 08:59 pm »


I don't see how the altitude at Quito would be a showstopper.

It location is a showstopper and altitude doesn't offset the other drawbacks

Offline Warren Platts

Re: The Reaction Engines Skylon Master Thread
« Reply #1083 on: 10/28/2012 11:09 pm »
Because Ecuador is a backwaters, 3rd world country with no modern infrastructure that's too far away from the centers that matter? I respectfully disagree. YMMV.

However...

Quote
In commercial aviation, launching at higher altitudes seriously decreases the max takeoff weight and thus range/payload. I doubt this will be different from Skylon.

I can see how this could be a deciding factor...
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline baldusi

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Re: The Reaction Engines Skylon Master Thread
« Reply #1084 on: 10/28/2012 11:36 pm »
Because Ecuador is a backwaters, 3rd world country with no modern infrastructure that's too far away from the centers that matter? I respectfully disagree. YMMV.
Equador is the third wost business friendly country this side of the Atlantic only ahead of Argentina and Venezuela. And then you'd have to overfly Brazil over the Amazonas.
Besides, for the Skylon you'd want a lot of LOX and LH2 production capabilities (that's US or Kourou this side of the Atlantic), easy trade rules (hahahhaa) and good tracking assets along the way (double hahahaha).
I told you already, Kourou would be a good place. But see the problem they had with telemetry and the Vega. Or KSC. I guess Alcantara has the potential, and the Brazilian government the money to make it a good place. May be Emirates, too. But this is only assuming an ITAR free plane.
« Last Edit: 10/28/2012 11:36 pm by baldusi »

Offline BobCarver

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Re: The Reaction Engines Skylon Master Thread
« Reply #1085 on: 10/29/2012 12:04 am »
But this is only assuming an ITAR free plane.

It is not only ITAR free, REL is bound and determined not to get caught up in US spy game idiocy. They already went through a horrendous problem with the British govt classification of HOTOL as "Top Secret."

Offline Kharkov

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Re: The Reaction Engines Skylon Master Thread
« Reply #1086 on: 10/29/2012 12:42 am »
When it comes to launch sites, a good place might be:

Kenya, either the port town of Lamu or nearby. 2 degrees south of the equator, with a port where you could bring in supplies. An alternative would be to build a railroad heading northwest, parallel to the Somalian border, until you hit the equator but there'd be greater costs involved. In either location, finding 15 square kilometres (3km x 5km) shouldn't be too hard. The downside is you're not far from the Somalian border.

You could manufacture LH/LOX aboard a ship or build a plant in the area.

Launching out of South America means either high altitude and/or heavy jungle/rainforest. Finding 15 square kilometres either way might be hard or involve lots of hard work.
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Offline baldusi

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Re: The Reaction Engines Skylon Master Thread
« Reply #1087 on: 10/29/2012 01:11 am »
Launching out of South America means either high altitude and/or heavy jungle/rainforest. Finding 15 square kilometres either way might be hard or involve lots of hard work.
Err.. have you heard of Alcantara? Kourou is where?

Offline Kharkov

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Re: The Reaction Engines Skylon Master Thread
« Reply #1088 on: 10/29/2012 03:49 am »
Launching out of South America means either high altitude and/or heavy jungle/rainforest. Finding 15 square kilometres either way might be hard or involve lots of hard work.
Err.. have you heard of Alcantara? Kourou is where?
Heard of? Yes. Know a lot about? No.

That said... Alcantara is in the province of Maranhao, which Wikipedia describes as '...northern portion of the state is a heavily forested plain traversed by numerous rivers...'

So I'm going off that, really. Remember that Skylon needs 5 Kilometres for it's takeoff run & due to noise, I'd imagine (I'm guessing but it seems reasonable to me) that you'd have 1,000mtrs to 1,500mtrs on either side to offer security, to avoid deafening the locals, to ensure that birds aren't nesting near enough to the runway to get sucked down the intakes etc.

I'm assuming that 15 square kilometres is needed but I'd happily accept a smaller figure if anyone qualified pops up & says so. I freely admit that I may be wrong but I'd say that Alcantara & Kourou probably don't have 15 square kilometres of flat, firm, stable, open, uninhabited land where a runway/hangar/processing facility with a security zone could be established.

On a separate note, I have a memory of watching Alan Bond (pretty sure it was him) saying that if the STRICT/STERN programme pays off, they'll be able to cut 1Km to 1.5Km off that 5Km takeoff run, but, for the life of me, I can't remember where I saw that or where I could find the video.

Could anyone confirm that and/or point me towards the video site?

EDIT: The required runway length, according to Mark Hempsell in the latest podcast from Talking Space Online, is 5.5Km, not 5Km as I stated. 4Km to get up to rotation, with another 1.5Km to stop if the takeoff is aborted at that point.
« Last Edit: 10/29/2012 06:41 am by Kharkov »
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Offline baldusi

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Re: The Reaction Engines Skylon Master Thread
« Reply #1089 on: 10/29/2012 04:12 am »
The current runway could only be extended to 3,300m. But to the East of Sao Luis you could easily do a 10km runway if you wanted.
In Kourou you could do a 15km runway. It already has tracking stations, integration facilities, hotels, range equipment, H2 and LOX factories, etc. It even has a solid fueling facility. And it's French soil. I can't think of a better place to launch the Skylon than Kourou, actually. Alcantara is a bit closer to the Equator (2,3deg vs 5,2deg), but the infrastructure difference, and the fact that Skylon can actually cover some distance while in the atmosphere without much penalty, make it pretty convincing argument. The only difference is that I think (repeat, I think) that Kourou requires a dogleg for SSO due to overflight risks, while Alcantara doesn't. But it's well within those things that would be very trajectory dependent.

Offline Warren Platts

Re: The Reaction Engines Skylon Master Thread
« Reply #1090 on: 10/29/2012 05:43 am »
The new Quito airport is already going to be 4 km, as is. Honestly, I can't see the showstopper here. Fully loaded 747's fly at 40,000 feet every day.  So it can't be the case that high-altitude per se limits the payload/fuel supply of air-breathing vehicles. Seems to me it would just be a function of take-off speed, which in turn would be a function of runway length.
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread
« Reply #1091 on: 10/29/2012 07:05 am »
A recent Mark Hempsell interview:

http://www.talkingspaceonline.com/home/episode-434-skylon-with-sabre-single-stage-to-orbit.html
3 interesting points in this interview.

1) The runway spec (4km with a 1.5km "runout" section if takeoff is aborted) is sized to allow completion of mission *despite* a loss of engine during takeoff (skylon has 2 in each nacelle). I'm guessing this is to allow for bird strikes (they're looking for aircraft certification and that is part of the standard). IOW it goes to *orbit* on 3 engines anyway.
If this were revised to takeoff, then burn off propellants and land IE an RTLS abort, that length could be *considerably* shorter but a LOE would then *guarantee* a LOM, which in a commercial environment would seriously annoy customers.
2) Their talks with companies that build airport runways indicate some are *already* being built to the spec they need in terms of weight carriage to ensure long life. This excludes the ones built in the US in the 1940s to handle the B36 strategic nuclear bombers of the time.
3) They would have loved to used the friction stir welding facilities at Michould because Skylon tanks are the order of size and material of the ET but ITAR is the problem. This also suggests they are moving to the idea of AlLi for the tanks rather than one of the 2000 series that have been historically spec'd for LV tanks. which suggests they are therefor no longer worried about quality and supply issues with this material in Europe.

BTW when SSTL built a microsat to demonstrate satellite rendezvous and inspection they were worried by *exactly* this issue. They wanted a US tank from one of the premier suppliers but had an 18 month schedule and *no* idea how long it would be stuck in paperwork.
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Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread
« Reply #1092 on: 10/29/2012 07:32 am »
The new Quito airport is already going to be 4 km, as is. Honestly, I can't see the showstopper here. Fully loaded 747's fly at 40,000 feet every day.  So it can't be the case that high-altitude per se limits the payload/fuel supply of air-breathing vehicles. Seems to me it would just be a function of take-off speed, which in turn would be a function of runway length.
For winged vehicles takeoff occurs when the lift per unit wing area exceeds takeoff mass. Air density is a *major* factor in calculating both the lift and the thrust from the engines. both are lower at higher altitudes. To offset that you have to lower your GTOW. Either fly with full payload and less fuel (shorter maximum range) or for long distance (as far as you could fly out of Newark or LAX) lower the baggage allowance or number of passengers.
But LV's don't have a range they have a *velocity* they have to hit and that does *not* change. Only payload can be reduced to hit the same orbital target.
*That* is the hit you take with a high altitude launch site.
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Offline 93143

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Re: The Reaction Engines Skylon Master Thread
« Reply #1093 on: 10/29/2012 08:11 am »
To first order, that's nothing you can't solve with a longer runway.

On the other hand, a baseline Skylon launch already has it moving close to Mach 0.5 in ground effect with the gear down.  First order doesn't always dominate...

Offline Warren Platts

Re: The Reaction Engines Skylon Master Thread
« Reply #1094 on: 10/29/2012 02:34 pm »
I'm not a pilot, but I did a little reading last night. Turns out hot weather can have some of the same effects as high altitude. According to the wikipedia in such hot and high conditions,

Quote
Some ways to increase aircraft performance in hot and high conditions include:

Reduce aircraft weight. ...
Increase engine power. ...
Increase the size of the wings. ...
Add high-lift devices to the wings. ...
Utilize assisted take off devices, such as rockets, to increase lift and acceleration.
Inject distilled water during takeoff in the engine (compressor or combustor). Evaporating water reduces the temperature, so more fuel can be added, increasing power.

Alternately, runway lengths may be increased to make up for reduced aircraft performance.

The world's highest commercial airport is Qamdo Bangda in Tibet at 14,219 ft. It also has the world's longest commercial runway at 18,045 feet (5.5 km). "With a 18,045 foot long runway the airport should be capable of handling the largest of the worlds airlines [sic]."

So it seems to me, it's mainly a matter of getting the airspeed up enough. Once they get airborne, if they launch from 15,000 feet, they've just saved themselves the fuel required to climb that first 3 miles of the 60 miles it takes to get into space (and 3/60 = 5%), so--other things being equal--the Skylon should be able to take on more fuel or payload than if it launched from sea level.
« Last Edit: 10/29/2012 06:46 pm by Warren Platts »
"When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."--Leonardo Da Vinci

Offline baldusi

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Re: The Reaction Engines Skylon Master Thread
« Reply #1095 on: 10/29/2012 02:57 pm »
Warren, do some more reading an look at the components of the speed needed for orbital insertion. 99% of the energy is horizontal, not vertical. The reason that traditional rockets launch vertically is because they try to get away of the atmosphere as fast as possible due to their low isp. Skylon has 10X isp on the atmosphere, thus it's not a problem. You are trying to solve a not a problem.
Infrastructure and business considerations are a lot more important. As I said, you can't beat Kourou in anything by five degrees from the equator. And you are assuming that there's no overflight problem at all! That any country will be ok with an hydrogen bomb flying above their cities? What about polar launches?

Offline BobCarver

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Re: The Reaction Engines Skylon Master Thread
« Reply #1096 on: 10/29/2012 03:44 pm »
Warren, do some more reading an look at the components of the speed needed for orbital insertion. 99% of the energy is horizontal, not vertical. The reason that traditional rockets launch vertically is because they try to get away of the atmosphere as fast as possible due to their low isp. Skylon has 10X isp on the atmosphere, thus it's not a problem. You are trying to solve a not a problem.
Infrastructure and business considerations are a lot more important. As I said, you can't beat Kourou in anything by five degrees from the equator. And you are assuming that there's no overflight problem at all! That any country will be ok with an hydrogen bomb flying above their cities? What about polar launches?

A hydrogen bomb? You need a smiley. This is an aircraft in the atmosphere, not a rocket, and will not pose any problem when overflying land.

Offline baldusi

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Re: The Reaction Engines Skylon Master Thread
« Reply #1097 on: 10/29/2012 03:50 pm »
It's a robotic aircraft with a ridiculously high GTOW percentage of which is liquid H2. In fact, since it uses O2 from the atmosphere when in plane mode, the amount of H2 is huge. Please remember that it's as or more heavy than an A380. Think what would be the precautions if this was road transported, and what are the dangers in case of a crash, for example.
Think of the amount of JP8 and how does it burns vs. H2.

Offline john smith 19

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Re: The Reaction Engines Skylon Master Thread
« Reply #1098 on: 10/29/2012 04:28 pm »
It's a robotic aircraft with a ridiculously high GTOW percentage of which is liquid H2.
High certainly. I think you'll find it's no worse than the plane Steve Fosset was flying on his solo round the world flight.
Quote
In fact, since it uses O2 from the atmosphere when in plane mode, the amount of H2 is huge. Please remember that it's as or more heavy than an A380.
Starting its takeoff roll yes. A chunk of that will go during the takeoff and climb out. Technically you could say that *all* of Skylons flight plan (it's an aircraft, not a missile) will be climb out (to orbit  :) )
as a robot a 45 deg takeoff slope is possible so 60kft downrange Skylon would be above *all* FAA jurisdiction. So if your runway is >12 statute miles from your countries border that would normally put it above most countries civil aviation oversight authority. 
Quote
Think what would be the precautions if this was road transported, and what are the dangers in case of a crash, for example.
I'd call that a pretty major straw man. It's *designed* to get into the air on 3 engines and they will be more than enough to burn off the propellant. Skylon is designed to land on empty, *purged* tanks, *without* active control movements (it's statically stable. It does not need the *continuous* computer generated control inputs jof the shuttle).
Quote
Think of the amount of JP8 and how does it burns vs. H2.
Hydrogen has a *very* broad explosive range (4% air to 96% air IIRC). The flame is nearly invisible as well.
However *if* a crash occurred and the tanks *did* rupture (I'd guess Skylon would be fitted with shock sensors to cut most if not *all* electrical power if a crash was detected. I'd *suspect* the immediate danger would be a)freezing hazard as the LH2 flash evaporated b)fragmentation damage from shrapnel due to pressure build up in the cryogenic tanks.
Analysis of the Hinderberg fire footage suggests GH2 fires burn *upwards* rather than outwards so while very dangerous while it is *dispersing* into the atmosphere GH2 disperses *very* quickly.

This assumes that *all* measures to vent propellants overboard through the surviving engines have failed.

I suspect the issue could *only* be settled by setting up a crash.
I wonder if that's part of the budget as well? 
MCT ITS BFR SS. The worlds first Methane fueled FFSC engined CFRP SS structure A380 sized aerospaceplane tail sitter capable of Earth & Mars atmospheric flight.First flight to Mars by end of 2022 TBC. T&C apply. Trust nothing. Run your own #s "Extraordinary claims require extraordinary proof" R. Simberg."Competitve" means cheaper ¬cheap SCramjet proposed 1956. First +ve thrust 2004. US R&D spend to date > $10Bn. #deployed designs. Zero.

Offline BobCarver

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Re: The Reaction Engines Skylon Master Thread
« Reply #1099 on: 10/29/2012 05:40 pm »
Talk of crash scenarios applies just as well to regular airliners, which SKYLON plans to be certified as, so anyone with that kind of imagination should live somewhere that airliners don't overfly or take medication for their nervous condition.  :)

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