[ExI] Reaction Engines in the US shuts down.

[Keith Henson]

On Sat, Nov 2, 2024 at 11:59 AM Ian Cash <ian at sicadesign.co.uk> wrote:
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> A solution for frost control in humid environments was amongst the earliest demonstrations from the REL team. I believe this was never patented, in-order to remain secret.

I know how it worked.  Not sure who explained it to me.  Involved
recirculating methyl alcohol.  I suggested another method of coating
the heat exchanger with a hydrophobic layer so the ice would not
stick.  Something must have worked since the testing in Colorado was
successful which it would not have been if the engine choked with ice.

Keith

> The SABRE engine uses a closed helium cooling loop, itself forming the working fluid for an efficient heat engine powering engine subsystems. The danger of a hydrogen-air mixing event is thus well-mitigated. Having the inlet airflow turn through a sharp 90 degrees also prevents the majority of foreign object damage, which continues to follow a near-straight path through bypass ducting.
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> This from 2015: https://www.ijirset.com/upload/2015/october/107_SABRE.pdf
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> "3. HELIUM LOOP:
> The hot HE from the precooler is reprocessed by cooling it in a heat exchanger with the LH2, heat absorbed by HE
> from incoming air is utilised to power various parts of engine developing a self-starting Brayton cycle based engine [9]. "
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> Ian
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> On 02/11/2024 18:26 GMT jamesmsnead at aol.com wrote:
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> Thank you, Ian, for the correction.
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> However, there do not appear to be any substantial difference in their approach from a LACE SSTO from a design closure point of view.
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> In developing the tailored ACES concept for the alternate NASP design, we addressed the condensation issue. In our approach, the nearly pure separated nitrogen was used as an intermediate coolant to control the condensation issue, if the humidity actually became an issue, and to prevent needing to use a hydrogen-air heat exchanger where a tube failure could cause a potential fire or explosion. We did not have coolant loops in the inlet to prevent FOD to the heat exchangers.
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> The intent was that the system would operate from air bases where the ground humidity was typically very low, such as Area 51. ��
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> I recently saw a YouTube video about a new hybrid electric jet engine concept that connected the turbine and the compressor via a generator-motor instead of a direct mechanical connection. For an ACES system, this may have interesting advantages in terms of being able to better control the bypass of air into the ACES system as a function of the flight conditions.
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> Also, the TSTO Boeing concept could see a future upgrade incorporating an ACES system in the carrier aircraft. This combined with new generation turboramjets enabling afterburning flight to Mach 3-4 would enable the system TOGW to drop significantly while reducing the ground refueling complexity.
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> Central to all of these discussions is the clear lack of effective functioning of the National Space Council. Proper space policy is highly dependent on thorough technical and operational analysis of current and in-development technologies. I do not see anyone doing this at this time. The ASD group at WPAFB was among the best. That effort has since gone away as the air side of the Air Force was “dismissed” from pursuing military spaceplanes.
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> Mike Snead, PE
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> From: Ian Cash <ian at sicadesign.co.uk>
> Sent: Saturday, November 2, 2024 12:14 PM
> To: jamesmsnead at aol.com; jamesmsnead via Power Satellite Economics <power-satellite-economics at googlegroups.com>; Keith Henson <hkeithhenson at gmail.com>; John K. Strickland, Jr. <jkstrickl at sbcglobal.net>
> Cc: willdcomstock <willdcomstock at gmail.com>; ExI chat list <extropy-chat at lists.extropy.org>; extropolis at googlegroups.com
> Subject: RE: Reaction Engines in the US shuts down.
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> Mike,
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> A more careful reading of the Wikipedia article could have saved you a lengthy reply on the shortcomings of LACE engines:
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> The low temperature of the air permits light alloy construction to be employed and allow a very lightweight engine—essential for reaching orbit. In addition, unlike the LACE concept, SABRE's precooler does not liquefy the air, letting it run more efficiently.[2]
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> Regards
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> Ian
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> On 02/11/2024 14:57 GMT jamesmsnead via Power Satellite Economics <power-satellite-economics at googlegroups.com> wrote:
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> Our analysis showed that a pure LACE SSTO did not yield design closure. So in the later 1980s, our analysis then showed that the Reaction Engines approach would probably not work.
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