The Reaction Engines Skylon Master Thread (1)

[Patchouli]

I wonder will Skylon use something similar to what ULA is proposing for their Integrated Vehicle Fluids concept to solve the problem of on orbit power and supplying GOX and H2 to the RCS system?
One thing that seems would be fitting is use of a hydrogen oxygen fueled ICE for the APU.
Of course with Skylon being reusable the high cost of fuel cells is probably less of an issue then it is with an expendable upper stage.

[john smith 19]

The largest truss framework aircraft I know of is the Messerschmitt Me 323 Gigant but I would not cite that as technology heritage. 

I had forgotten about the Me323. It's *huge*.  It's too bad that it's proportions are very different from Skylon's.

Thank you for continuing to post to this thread. The announcement on the 1st phase of the pre-cooler costs was very positive.

In regard to funding I am unclear but was the next stage of funding conditional on passing this phase, the 2nd phase that's starting or all 3 test phases of the pre-cooler?

It was my impression that even in phase 1 the outlet from the pre-cooler would already be below zero and frost control would have to be working or the structure would be seriously damaged, which seemed to be the decision gate for releasing the £200m block.

aero “I'm wondering why it costs $10 billion to get something flying.”

Because it doesn’t - $10 billion includes the qualification programme to get the plane into operational service not just the first flight.  It is comparable to the cost of a large civil jet program such as the Airbus A380 for pretty much the same reasons.

I think this is a point (along with the fact Skylon gives you ELV payload fraction in an SSTO vehicle) that should be better emphasized.

People who are not familiar with the project see that figure and wonder why it's so much bigger than say the EELV programme for either Delta or Atlas.

They see the cost to get to the 1st LV *rather* than including the full cost of qualification launches, and the substantial post flight analysis (and any associated modifications that analysis shows to be necessary) and the re-flights to confirm the changes. This also disregards the cost of funding from commercial lenders.

I understand that including a *full* test programme in the cost estimate REL is demonstrating to lenders there are no hidden "extras," that in reality you would have to get funding for down the line to get type approval. Would it be possible to *publicly* give a figure for how much it would take to get to the 1st orbital capable vehicle? Not for sale (and possibly not full sized) but to fly the full envelope and demonstrate HTOL SSTO from takeoff to orbit to landing.

I believe that ability to deliver down mass is another significant part of its appeal. A one way demonstration trip to orbit would not be sufficient.

[Hempsell]

Some comments on recent posts

MikeAtkinson “Do you think there is a market for non-commercial Skylons? By non-commercial I mean countries and other organisations that operate Skylon(s) for reasons other than profit. These reasons might include military, assured access to space, national prestige, perhaps even a billionaires personal Skylon.”

Yes of course – once a SKYLON has been purchase what the owner does is pretty much up to him and not all owners will have primarily commercial motivations.  This means that the will need to be some agreed rules so that non-commercial operators do not steal launches from those trying to operate commercially - I suspect there will need to be some World Trade Organization thinking on this.

adrianwyard re: Business models –“Is there a better source? Perhaps this sort of thing is confidential...”

The Requirement Review material you refer to is not really supposed to be public domain and certainly the other customer business material is company confidential.

simonbp “I really like the reusable upper stage. It neatly solves the issue of a fully-reusable GTO launch system without the complexity of Fluyt. Presumably that's a single Vinci engine?”

No we only use the Vinci for the Fluyt stage.  Our current concept for a reusable upper stage uses the SKYLON Orbital Manouvering engine Assembly called SOMA.  This is a two engine (two chambers per engine) cluster with a total thrust of 200 kN.  There is a JBIS paper on the Upper Stage Mark Hempsell and Alan Bond  TECHNICAL AND OPERATIONS DESIGN OF THE SKYLON UPPER STAGE  JBIS, Vol. 63, pp.136-144, 2010


Patchouli “I wonder will Skylon use something similar to what ULA is proposing for their Integrated Vehicle Fluids concept to solve the problem of on orbit power and supplying GOX and H2 to the RCS system?  One thing that seems would be fitting is use of a hydrogen oxygen fueled ICE for the APU.  Of course with Skylon being reusable the high cost of fuel cells is probably less of an issue then it is with an expendable upper stage.

Basically the answer is yes.  There is a gaseous feed created from the orbital propellant tanks which sends hydrogen and oxygen to the RCS thrusters, fuel cells and APU (although the APU might be replaced by bigger fuels cells and a more electric design approach to actuation).

john smith 19 on costs

The subject of costs and prices is very complex and quoting numbers is increasingly difficult because although everyone is asking what seems to be the same question “how much is it going cost to get into space” the real answer is what do mean by cost?, what do you man by space? And after all that the final the bottom line answer is “it depends”.

Our objective is to get to a point where the price charged for the launch covers every activity leading up to it (the launch system manufacture the spaceport and the operator), with taxes and profit i.e. a fully economic activity with no market failure.  So we try to quote costs that are in line with this objective.

[EdgePenguin]

I've a couple of questions about how someone would operate Skylon:

1. The special runway required; is this a new kind of construction technique, or do sufficiently strengthened runways exist already?

2. How would an operator receive their Skylon? I can't see it fitting on top of an aircraft or a train, and taking it by sea would limit the locations you can launch from. I had originally imagined Skylon flying from the factory to the operators facility, but I then got the impression it wouldn't be able to perform such a flight as it would involve spending too long in the atmosphere?

3. Any idea how noisy the SABRE engine is likely to be? How much clearance around the launch facility (and the flight path) is going to be required? I can't see these things taking off from Heathrow...

[Hempsell]

I've a couple of questions about how someone would operate Skylon:

1. The special runway required; is this a new kind of construction technique, or do sufficiently strengthened runways exist already?

2. How would an operator receive their Skylon? I can't see it fitting on top of an aircraft or a train, and taking it by sea would limit the locations you can launch from. I had originally imagined Skylon flying from the factory to the operators facility, but I then got the impression it wouldn't be able to perform such a flight as it would involve spending too long in the atmosphere?

3. Any idea how noisy the SABRE engine is likely to be? How much clearance around the launch facility (and the flight path) is going to be required? I can't see these things taking off from Heathrow...

The runway needs to be stronger than normal – but it would be made by conventional methods.  We understand from the consulting company on the team which specialises in airport construction that some very high traffic airports are already putting in runways with this sort of strength.  The extra length is just extra length and the last 1.5 km is a run-off area which does not need the same high strength.

With regard to delivery; SKYLON needs to be air transportable in some way to get it out from contingency airfields and down range airfield.  The past assumption was we would use an air tow (when empty it is not a bad glider) but more recent work suggests with just hydrogen on board it could fly itself.  In this mode it does not need anything special by way of a runway and would have a large ferry range.  Also as the airframe is lightly loaded during such flights so it should not have any significant impact on the structure’s life.  So currently we are assuming the SKYLON would fly itself from the factory to the operator’s spaceport for delivery.

The launch will be very very noisy - Space Shuttle levels.  When combined with the runway requirements and the special propellant facilities it is clear, SKYLONs will not be taking off from airports like Heathrow, rather we expect operators to use specialist spaceports.

[A_M_Swallow]

{snip}
With regard to delivery; SKYLON needs to be air transportable in some way to get it out from contingency airfields and down range airfield.  The past assumption was we would use an air tow (when empty it is not a bad glider) but more recent work suggests with just hydrogen on board it could fly itself.  In this mode it does not need anything special by way of a runway and would have a large ferry range.  Also as the airframe is lightly loaded during such flights so it should not have any significant impact on the structure’s life.  So currently we are assuming the SKYLON would fly itself from the factory to the operator’s spaceport for delivery.

Spaceports from which SKYLON flies regularly will have their own source of hydrogen but contingency airfields may not.  Consequently hydrogen tanks that can be air freighted to the contingency airfields will need designing.  Filling the SKYLON may require more than one tank.

[Seer]

Why is the launch noiser than a normal jet?

[adrianwyard]

Why is the launch noiser than a normal jet?

Because it's a rocket (which happens to be able to use air for the oxidiser up to Mach 5). The acronym SABRE stands for Synergistic Air Breathing Rocket Engine.

http://www.reactionengines.co.uk/sabre.html

I've wondered if the takeoff will look a bit more rocket-like than how it's depicted in the animations. In those the exhaust plume looks rather like a Concorde take-off where the reheat just added those nice Mach diamonds. However, with Skylon we need to picture eight rocket engine bells with an exhaust similar to that of the Shuttle SSMEs... Quite impressive! And it's probably a good thing the runway is re-inforced as these engines are pointing at it...

[Warren Platts]

{snip}
With regard to delivery; SKYLON needs to be air transportable in some way to get it out from contingency airfields and down range airfield.  The past assumption was we would use an air tow (when empty it is not a bad glider) but more recent work suggests with just hydrogen on board it could fly itself.  In this mode it does not need anything special by way of a runway and would have a large ferry range.  Also as the airframe is lightly loaded during such flights so it should not have any significant impact on the structure’s life.  So currently we are assuming the SKYLON would fly itself from the factory to the operator’s spaceport for delivery.

Spaceports from which SKYLON flies regularly will have their own source of hydrogen but contingency airfields may not.  Consequently hydrogen tanks that can be air freighted to the contingency airfields will need designing.  Filling the SKYLON may require more than one tank.

That's what lorries are for...

[A_M_Swallow]

{snip}
With regard to delivery; SKYLON needs to be air transportable in some way to get it out from contingency airfields and down range airfield.  The past assumption was we would use an air tow (when empty it is not a bad glider) but more recent work suggests with just hydrogen on board it could fly itself.  In this mode it does not need anything special by way of a runway and would have a large ferry range.  Also as the airframe is lightly loaded during such flights so it should not have any significant impact on the structure’s life.  So currently we are assuming the SKYLON would fly itself from the factory to the operator’s spaceport for delivery.

Spaceports from which SKYLON flies regularly will have their own source of hydrogen but contingency airfields may not.  Consequently hydrogen tanks that can be air freighted to the contingency airfields will need designing.  Filling the SKYLON may require more than one tank.

That's what lorries are for...

Lorries find getting to Pacific islands a little difficult.

[douglas100]

Lorries find getting to Pacific islands a little difficult.

Compared with designing, building and flying a revolutionary space vehicle, the provision of propellant at diversionary airfields is trivial.

[A_M_Swallow]

Lorries find getting to Pacific islands a little difficult.

Compared with designing, building and flying a revolutionary space vehicle, the provision of propellant at diversionary airfields is trivial.

True but forgetting to add the details to the plan can be embarrassing.

[zt]

How difficult is it to transport liquid hydrogen?

[baldusi]

With regard to delivery; SKYLON needs to be air transportable in some way to get it out from contingency airfields and down range airfield.  The past assumption was we would use an air tow (when empty it is not a bad glider) but more recent work suggests with just hydrogen on board it could fly itself.  In this mode it does not need anything special by way of a runway and would have a large ferry range.  Also as the airframe is lightly loaded during such flights so it should not have any significant impact on the structure’s life.  So currently we are assuming the SKYLON would fly itself from the factory to the operator’s spaceport for delivery.

How much distance would Skylon be able to cover without significant payload degradation? Let's say, for example, that you launch from Alcantara, could you reach 0 degrees (270km) latitude with little performance cost?

[aero]

Soon enough someone is going to bring up the concept of air-to-air refueling of hydrogen fuel. Of course it could be made to work but in what circumstances would it provide any benefit?

[douglas100]

True but forgetting to add the details to the plan can be embarrassing.

What makes you think that such an important detail would be forgotten in planning for the operation of Skylon?

[A_M_Swallow]

True but forgetting to add the details to the plan can be embarrassing.

What makes you think that such an important detail would be forgotten in planning for the operation of Skylon?

I had not seen anyone mentioned it.  On other projects I have seen too many things that could have been done cheaply at the right time turn into large cost overruns at the end.

[e of pi]

Well, it seems they have enough options: they can place hydrogen production sites at the spaceports that Skylon will be operating from regularly. At emergency landing sites where it's uneconomical to provide a full plant, they either can make arrangements to deliver LH2 by truck, ship, or aircraft, or they can revert to the tow mode they were planning on before realizing that powered hydrogen-only flight was doable. That seems plenty well-thought-out, given where they are in the program.

[adrianwyard]

I've wondered if the takeoff will look a bit more rocket-like than how it's depicted in the animations. In those the exhaust plume looks rather like a Concorde take-off where the reheat just added those nice Mach diamonds. However, with Skylon we need to picture eight rocket engine bells with an exhaust similar to that of the Shuttle SSMEs... Quite impressive! And it's probably a good thing the runway is re-inforced as these engines are pointing at it...

Now I think about it the rockets could presumably be gimballed to point directly aft until V1 speed, and only pointed Earthward at the last minute to get airborne, and at that speed the plume doesn't hit much runway area for very long.

And getting back to noise: my suspicion is that anyone who buys a ticket for a Skylon passenger module will be handed some nice heavy duty noise-canceling headphones for the takeoff.

[alexterrell]

The launch will be very very noisy - Space Shuttle levels.  When combined with the runway requirements and the special propellant facilities it is clear, SKYLONs will not be taking off from airports like Heathrow, rather we expect operators to use specialist spaceports.

It would be a nice PR stunt to do a launch from Heathrow.

But, easterly flights direct over London? The need to grab a few slots (normal take-offs a minute before and a minute after probably not feasible).

May be not.

Not sure if you answered this: Is there an altitude limit? I'd guess takeoff from Denver would not be feasible.