So listening to the bit about electric power production made me wonder about the potential for hybrid electric propulsion. If a distributed electric propulsion element could be integrated with the SABRE hypersonic platform it might improve takeoff noise and thrust and allow improved subsonic efficiency.
It occurred to me that the SABRE cycle would integrate well with a a solid oxide fuel cell given that it produces high temperature hydrogen in the right temperature range and that it has excess hydrogen at points in the cycle and that the cryogenic hydrogen would be available to cool superconducting motors.
A hypersonic platform that could loiter efficiently at subsonic speeds might be useful, or indeed one that could takeoff quietly and fly efficiently over land.
The question I guess is could distributed motors be integrated in such a way that they can be protected at hypersonic speeds.
Quote from: lkm on 03/12/2017 12:13 amSo listening to the bit about electric power production made me wonder about the potential for hybrid electric propulsion. If a distributed electric propulsion element could be integrated with the SABRE hypersonic platform it might improve takeoff noise and thrust and allow improved subsonic efficiency.SABRE is an engine for an LV. For this to be a net win you have to factor in what the extra weight will buy you over the whole trajectory.
Quote from: lkm on 03/12/2017 12:13 amIt occurred to me that the SABRE cycle would integrate well with a a solid oxide fuel cell given that it produces high temperature hydrogen in the right temperature range and that it has excess hydrogen at points in the cycle and that the cryogenic hydrogen would be available to cool superconducting motors.And these motors are doing what exactly?
Quote from: lkm on 03/12/2017 12:13 amA hypersonic platform that could loiter efficiently at subsonic speeds might be useful, or indeed one that could takeoff quietly and fly efficiently over land.Then you be looking at the Scimitar work REL did for LAPCAT.
Quote from: lkm on 03/12/2017 12:13 amThe question I guess is could distributed motors be integrated in such a way that they can be protected at hypersonic speeds.Such motors would have to be integrated into the wing of the vehicle, not SABRE. Skylon's wing is sized for high speed takeoff because that's what REL trade studies indicate is the best way to save overall weight on the whole trajectory. The major issue with fuel cells is that they are tough if you don't have a supply of H2. Once you've a supply there are about half a dozen approaches to choose from and Skylon is H2 powered to begin with. REL expect Skylon to use fuel cells for on orbit power anyway for reasons I don't quite understand why, given that water (useful for a human crew) is just a waste product for an uncrewed vehicle that has to be either stored or vented overboard.
Designing Efficient Multi-Stage Counter Rotating Turbines for Rocket EnginesContact: Lead Supervisor: Dr. Graham Pullan Department of EngineeringProject AvailableProject Description:The concept of a counter rotating turbine has existed for almost as long as the jet engine, however in practise they are very rarely used. The idea is that instead of alternating between stationary and rotating aerofoils the machine alternates between aerofoils rotating in opposite directions.There are many claims of much higher work output and improved efficiency compared to conventional turbines. This is often put down to the removal of the stationary vanes which are not generating any work output. Initial studies show that to achieve the increased work output previously claimed, results in very high relative blade speeds and hence high (>1) mach numbers when matched to a conventional gas turbine cycle. The high speed flow increases the loss and in reality the claims of improved efficiency are not realised.A recent proposal for an air breathing rocket engine by Reaction Engines LTD currently includes a multi-stage counter rotating turbine linked to a conventional compressor. The reason such a design is of interest is that the turbine is operating with Helium as the working fluid, for which the speed of sound is roughly 3 times higher than air. This enables a successful CRT to operate without the performance penalty associated with high Mach numbers. However the design of such a system has been attempted only a handful of times and there is clear room for improvement.An additional feature of multi-stage CRTs is that in an idealised infinite machine only one blade need be designed, it being employed for both rotors. This project aims to utilise this feature and the assumption of a true multi-stage machine, to simplify the problem and produce a high efficiency design for this relatively poorly understood type of machine. If a good design can be produced it is likely that generic design rules can be developed for this type of machine.Link to Reaction Engines LTD Requirements: Aerodynamics modules 3A1 and 3A3. It is expected that the UROP should lead into a 4th year project. The project is being co-supervised by Dr. C. Clark , Dr. S. Grimshaw and Dr. J. Taylor Please contact Dr. S Grimshaw for further details or to apply.Insertion Date: 9 March 2017
Super Aggressive S-shaped Ducts for Rocket Engine CompressorsContact: Lead Supervisor: Prof. Rob Miller Department of EngineeringProject AvailableProject Description:Within a gas turbine there are often multiple shafts, which can have significantly different rotational speeds. To provide suitable blade speeds for the compressor, the radius of the annulus is sometimes changed between the two shafts. This change is performed in an interstage duct, the design of which represents an interesting engineering challenge.It is found in practise that shorter ducts incur higher aerodynamic losses due to the increased endwall diffusion. Thus there is a trade-off for the designer between duct length and weight and aerodynamic performance. In land based gas turbines for power, where weight is not an issue, the aerodynamic performance is favoured. In an aerospace engine the trade-off is much more competitive as both weight and performance are desirable.A recent proposal for an air breathing rocket engine by Reaction Engines LTD includes such a duct between the two compressor shafts. This engine, SABRE, is proposed for use on the SKYLON space plane. As such, minimising engine weight to allow for larger payloads is even more important than in jet engine applications.This project will study the more "aggressive" end of the S-shaped duct spectrum. It is hoped that a design philosophy for such aggressive ducts can be developed as well as an understanding of the trade-off between length and performance of these designs.The project is likely to include simple axi-symmetric computational fluid dynamics calculations to aid in the design, study and production of such ducts. With sufficient progress, designs of interest could be manufactured and tested aerodynamically in a low speed facility within the Whittle Laboratory.Link to Reaction Engines LTD Requirements: Aerodynamics modules 3A1 and 3A3. It is expected that the UROP should lead into a 4th year project. The project is being co-supervised by Dr. C. Clark , Dr. S. Grimshaw and Dr. J. Taylor Please contact Dr. S Grimshaw for further details or to apply.Insertion Date: 9 March 2017
So definitely British then?
This is interesting because of the picture which looks like a skylon and the idea that the "wing hairs" or whatever I should call them are possibly being looked at to let it land at a slower speed. https://www.theengineer.co.uk/falcon-flight-inspires-next-gen-aircraft/
Quote from: t43562 on 03/23/2017 04:12 pmThis is interesting because of the picture which looks like a skylon and the idea that the "wing hairs" or whatever I should call them are possibly being looked at to let it land at a slower speed. https://www.theengineer.co.uk/falcon-flight-inspires-next-gen-aircraft/I wouldn't get too carried away. Now that BAe have invested in REL their PR dept no doubt feels an urge to slap a "Skylon like" vehicle on most of their stuff.Would it be great if BAe went seriously into the idea of an SSTO LV. Yes. Do people think they will. Not so much.
Quote from: Paul451 on 03/17/2017 11:22 pmSo definitely British then?Unfortunately so, I think, because that would mean it's highly unlikely to happen. I'm just thinking that if the e-go, a tiny aeroplane, cannot make a go of it in the UK then what chance a hypersonic business jet?
Quote from: t43562 on 03/19/2017 06:20 amQuote from: Paul451 on 03/17/2017 11:22 pmSo definitely British then?Unfortunately so, I think, because that would mean it's highly unlikely to happen. I'm just thinking that if the e-go, a tiny aeroplane, cannot make a go of it in the UK then what chance a hypersonic business jet? Sad but true. It wasn't long ago that I read that Airlander long term is be brought by a company. This country lack leaders and visionaries that can turn things like Airlander into a global company. http://www.cityam.com/257097/company-behind-airlander-flying-bum-planning-ipo-london
The most visible difference seems to be going from four chambers to one, but are there other major differences?This new version is much smaller than the original?
This was tweeted today from the Reaction Engines Inc (US subsidiary) twitter accounthttps://twitter.com/ReactionEngUSA/status/849679715283742726They seem to have a new engine model that looks substantially different to the previous one. They also tweeted a number of other pictures at slightly different angles.Edit: In fact the banner across the top of the ReactionEngUSA twitter page is an image of this new model.