Talk:Lockheed Martin SR-72

Wow, that didn't take long...

I was wondering after hitting Space Daily this morn why somebody didn't beat me to starting this article. Thanks for saving me the trouble :) I'll add some links tomorrow. Doyna Yar (talk) 03:32, 2 November 2013 (UTC)

This article seems relevant. TGCP (talk) 22:03, 2 November 2013 (UTC)

Obsolete SR-71?

It is not correct to say the SR71 is obsolete. It was very expensive to build and operate. If the USA was willing to pay the money to keep it flying, it would still be able to perform useful missions.

The correct description is "retired". Saltysailor (talk) 18:03, 5 November 2013 (UTC)

Retired Date of SR-71

The SR-71 was retired in 1990, as it's article correctly indicates, not 1998. They set additional records with it in the final flight of one of them, so it's easily confirmed. Sorry if I'm doing something wrong here, it's the first comment I've ever made on Wikipedia. 24.89.20.205 (talk) 13:52, 6 November 2013 (UTC)

Good question, and you did it right. The SR-71 was retired twice. The first time was in 1990, but 3 were reactivated in 1995, and then retired in 1998 for the last time. See Lockheed SR-71 Blackbird#Reactivation and the next section there for more info on this. Thanks. - BilCat (talk) 15:15, 6 November 2013 (UTC)

Ramjet mach number

"Normal ramjets cannot typically operate over Mach 4.0"

Where did this come from?

The source at the end of the sentence claims "Most ramjets are not capable of operating at speeds below M4.0"

The Wikipedia claim contradicts Skunkworks' "Mach 6 with ramjets" idea, and the source is flat out wrong, since most ramjet so far have in fact operated below Mach 4.0 (see for example the Bristol Bloodhound, dual ramjets at Mach 2.7). — Preceding unsigned comment added by 83.251.126.182 (talk) 10:39, 7 November 2013 (UTC)

Regardless of source material, the sentence grammar makes it sound like ramjets will not work going faster than mach 4.0. Perhaps the sentence should read something like; "Normal ramjets cannot typically operate under Mach 4.0" or perhaps, "Typically ramjets perform best when operating over speeds in excess of Mach 4.0.", or something along those lines. If a ramjet can not reach speeds past Mach 4.0 and Turbojets have trouble with speeds over Mach 2.2, how can the SR-72 reach over mach 6 if it uses a hybrid engine that combines the two?

Amusingly, Wikipedia's very own entry on ramjet states " Ramjets work most efficiently at supersonic speeds around Mach 3 ".

So we have ramjets not operating under mach 4, ramjets only working over mach 4, and ramjets being most efficient at mach 3. Oooooookay... — Preceding unsigned comment added by 91.198.164.1 (talk) 14:05, 13 March 2015 (UTC)

Recently, PopSci noted that Ramjets 'typically' begin operating at approximately Mach 4. Perhaps this carries importance? http://www.popsci.com/inside-americas-next-spyplane. OC39648 (talk) 20:51, 3 June 2015 (UTC)

Not only that, but the figures are contradicted right inside this very same article: "Ramjets, using aerodynamic compression with subsonic combustion, perform poorly under Mach 0.5 and are most efficient around Mach 3, being able to go up to around Mach 6." Making it sound like they can perform as low as 0.5 just fine. Kolzene (talk) 12:11, 6 June 2015 (UTC)

The PopSci article is wrong, obviously. They might've mixed it up with scramjets. The SR-71's J58 engines transition to ramjet at ~M2 and reach M3.2, peaking at possibly M3.5. --Zac67 (talk) 14:42, 6 June 2015 (UTC)

Looking at previous scramjet tests, Zac67's theory looks to be correct, turbojets from mach 0-2.2, ramjets 2.2-4 (albeit 4 is fairly high for ramjet), scramjets 4 and onwards. — Preceding unsigned comment added by 24.171.89.170 (talk) 03:07, 8 July 2015 (UTC)

Relevant Detail

How much of the detail in this is really relevant? There's like 100 paragraphs on the challenges of hypersonic aircraft design for a plane that was really clearly never intended to actually fly or do anything but grab headlines. Apophenic (talk) 00:23, 12 February 2018 (UTC)

Were any relevant contracts awarded or extended since December 2014

All the talk in 2017 seems to be just lobbying for more work ? When was the Dec 2014 contract meant to run until ? - Rod57 (talk) 08:42, 2 May 2018 (UTC)

New materials?

Hi, looked into this shortly after "Maverick" was released. Incidentally new materials have only recently been discovered using gold alloys (AuxTiy) with anomalously high melting points. Using active magnetic and or electrical methods may allow direct electrical drive of the engine reducing complexity considerably though making the engine useless below Mach 4 so it would be more of an additional component. The closest analogy is a plasma dynamic drive similar to the purported "Caterpillar" or MHD drive that powered the Yamato.

References

91.190.161.160 (talk) 14:27, 22 May 2024 (UTC)