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#1 Greg Locock

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Posted 26 September 2013 - 09:33

Proper stuff

 

http://www.enginehistory.org/index.php

 

I must admit I hadn't realised that aeronautical sleeve valves were driven by such a curious mechanism.



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#2 Wuzak

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Posted 26 September 2013 - 11:24

I must admit I hadn't realised that aeronautical sleeve valves were driven by such a curious mechanism.

 

The little cranks, or the number required for Bristol sleeve valve radials?

 

It seems that all the British aero engine makers used the same, or similar, cranks to drive the sleeve. Pratt & Whitney developed a different system to avoid having to pay royalties - I assume to Riccardo, since he was the guy that pushed for sleeve valves.

 

The exception was the Rolls-Royce Crecy - it used eccentrics on the crank to drive the sleeves.



#3 rory57

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Posted 26 September 2013 - 11:26

I must admit I hadn't realised that aeronautical sleeve valves were driven by such a curious mechanism.

 

This (contemporary) sleeve valve aero engine is less complex, but I don't think it will scale-up much.

 

sp-engine-crosssection.jpg

 

 http://www.rcvengine...indervalve.html



#4 rory57

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Posted 26 September 2013 - 11:52

The little cranks, or the number required for Bristol sleeve valve radials?

 

It seems that all the British aero engine makers used the same, or similar, cranks to drive the sleeve. Pratt & Whitney developed a different system

to avoid having to pay royalties - I assume to Riccardo, since he was the guy that pushed for sleeve valves.

 

I don't know about the royalties issue, but the Pratt and Whitney design looks more compact than that used by Napier / Rolls Royce in their H-24 engines, doesn't require handed sleeves like the Napier engine.

 

The exception was the Rolls-Royce Crecy - it used eccentrics on the crank to drive the sleeves.

 

Much easier with the two stroke Crecy, just up and down phased to open the the exhaust ports. The top of the sleeve also contributes to "piston area" so sleeve is virtually gas-pressure powered.



#5 Wuzak

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Posted 26 September 2013 - 12:44

 

The little cranks, or the number required for Bristol sleeve valve radials?
 
It seems that all the British aero engine makers used the same, or similar, cranks to drive the sleeve. Pratt & Whitney developed a different system
to avoid having to pay royalties - I assume to Riccardo, since he was the guy that pushed for sleeve valves.
 
I don't know about the royalties issue, but the Pratt and Whitney design looks more compact than that used by Napier / Rolls Royce in their H-24 engines, doesn't require handed sleeves like the Napier engine.

 


Looks can be deceiving.

They were certainly narrower than the Sabre - IIRC they were designed to be buried in the wings of large aircraft (with cylinders horizontal). Much of that is to do with the mounting of accesories. The Sabre had them on top.

Also I think the Sabre was narrower across the cylinder heads than the X-1800, etc. It certainly was shorter - by some 20".

 

 

The exception was the Rolls-Royce Crecy - it used eccentrics on the crank to drive the sleeves.
 
Much easier with the two stroke Crecy, just up and down phased to open the the exhaust ports. The top of the sleeve also contributes to "piston area" so sleeve is virtually gas-pressure powered.

 


The Crecy system still gave a similar motion. the sleeve drive mechanism was connected to 2 sleevs and a little crank and piston which kept the whole thing oriented.



#6 Wuzak

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Posted 26 September 2013 - 12:49

The Diesel version of the Kestrel with sleeve valves.

 

http://www-g.eng.cam...ardo/page46.htm

 

There was also a petrol version - but I can't recall which came first.

 

The petrol version (RR/P) made slightly less power than the equivalent Kestrel, but it did also give away capacity to the Kestrel (for the sleeves).

 

The diesel version (RR/D) disappointed in its power output, and kept breaking (mostly) the  standard Kestrel parts.

 

They were both very much heavier than the standard Kestrel. Mainly because of the two sets of gear drives down the sides of the crankcase.



#7 Magoo

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Posted 26 September 2013 - 13:17

Proper stuff

 

http://www.enginehistory.org/index.php

 

I must admit I hadn't realised that aeronautical sleeve valves were driven by such a curious mechanism.

 

 

Great website. If you ever see any back issues of the Society's Torque Meter magazine, grab them up. I see the website sells them as well. 



#8 bigleagueslider

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Posted 27 September 2013 - 04:55

The little cranks, or the number required for Bristol sleeve valve radials?

 

It seems that all the British aero engine makers used the same, or similar, cranks to drive the sleeve. Pratt & Whitney developed a different system to avoid having to pay royalties - I assume to Riccardo, since he was the guy that pushed for sleeve valves.

 

The exception was the Rolls-Royce Crecy - it used eccentrics on the crank to drive the sleeves.

 

The Bristol Centaurus/Hercules, Napier Saber, and Rolls-Royce Kestrel/Eagle/Pennine were 4-strokes that required a sleeve valve reciprocating at 1/2 the piston rate. All of these engines used a small cantilevered eccentric crank and spherical bearing mechanism to drive the sleeve.  The arrangement used on the Bristol radials outwardly appears to be more complex than the drives used on the in-line engines, but in reality it was probably no worse.  All of the 4-stroke sleeve valve engines used at least one pair of gears to drive each sleeve valve crank.  The only exception, as Wuzak noted, was the 2-stroke Crecy. The Crecy used a system of connecting rods driven by eccentric lobes on the crank webs, and the sleeve conrods were kept aligned by a small auxiliary piston connected to it and reciprocating within a bore in the crankcase.

 

The major difference between the 4-stroke and 2-stroke sleeve valves was the porting arrangement.  The 4-strokes had both intake and exhaust ports in the upper end of the sleeve, wwhile the 2-strokes had the intake and exhaust ports at opposite ends.



#9 Wuzak

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Posted 27 September 2013 - 06:37

The arrangement used on the Bristol radials outwardly appears to be more complex than the drives used on the in-line engines, but in reality it was probably no worse.  All of the 4-stroke sleeve valve engines used at least one pair of gears to drive each sleeve valve crank. 

 

I suppose it looks more complicated because they have 14 cranks (and gear sets) for the Hercules and 18 for the Centaurus. The Sabre, Rolls-Royce Eagle 22 (H-24) and Rolls-Royce Pennine (X-24) only used two gear sets to drive the sleeve drive shafts, which drove cranks that worked 2 cylinders..

 

The sleeve valve Kestrels RR/P and RR/D used a crank and gear set for each sleeve, but if Rolls-Royce had made a production V-12 4-stroke I am guessing it would have used a single shaft driving the cranks.



#10 Allan Lupton

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Posted 27 September 2013 - 13:48

I suppose it looks more complicated because they have 14 cranks (and gear sets) for the Hercules and 18 for the Centaurus. The Sabre, Rolls-Royce Eagle 22 (H-24) and Rolls-Royce Pennine (X-24) only used two gear sets to drive the sleeve drive shafts, which drove cranks that worked 2 cylinders..
 
The sleeve valve Kestrels RR/P and RR/D used a crank and gear set for each sleeve, but if Rolls-Royce had made a production V-12 4-stroke I am guessing it would have used a single shaft driving the cranks.

Probably right so long as you do mean "driving the cranks" as you wrote. To get the orbital motion needed for the Burt-McCollum single sleeve valve, the rotational axis of the operating crank intersects the cylinder centreline so an overhung crank is required so the most valve cranks on one shaft are the pairs of those cranks used in the H-pattern Sabre, Eagle, etc. That pairing is not as simple on a V-format engine.
Knight (double) sleeve valves which just move up and down can be run from one shaft as in Daimler/Panhard/etc. car engines.

#11 Magoo

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Posted 27 September 2013 - 17:05

Discuss. 

 

 



#12 NeilR

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Posted 28 September 2013 - 09:50

Thanks greg, very interesting



#13 indigoid

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Posted 28 September 2013 - 10:24

Discuss. 

 

All those leetle gears!

 

And it looks like you would need a man installed behind the engine, continually pouring buckets of oil into it. Did they have a lot of sealing problems early on with this sleeve valve stuff?



#14 bigleagueslider

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Posted 29 September 2013 - 03:01

All those leetle gears!

 

And it looks like you would need a man installed behind the engine, continually pouring buckets of oil into it. Did they have a lot of sealing problems early on with this sleeve valve stuff?

The gears, cranks and spherical bearings used in the 4-stroke sleeve valve drives were never really a problem.  However, the high oil consumption rate of sleeve valve engines was an issue that was never fully resolved.  Oil consumption of aircraft sleeve valve engines was mitigated due to the fact that these engines were supercharged, and thus never were subject to a negative pressure differential between the intake and crankcase created by intake throttling that would have resulted in lube oil being drawn into the intake airflow in a N/A engine.



#15 gruntguru

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Posted 30 September 2013 - 07:48

these engines were supercharged, and thus never were subject to a negative pressure differential between the intake and crankcase created by intake throttling that would have resulted in lube oil being drawn into the intake airflow in a N/A engine.

Never?

"Less often" perhaps, but closed-throttle running will still produce "vacuum" as with a NA engine.



#16 Lee Nicolle

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Posted 30 September 2013 - 10:00

Proper stuff
 
http://www.enginehistory.org/index.php
 
I must admit I hadn't realised that aeronautical sleeve valves were driven by such a curious mechanism.

That site has so much I think I would have to retire to read it and take it all in. I spent about 40 min reading about Pratt and Whitney radial engine viabration problems. After that gimme a jet!

#17 indigoid

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Posted 30 September 2013 - 16:59

So while we were visiting the UK in April we went to IWM Duxford specifically to see this beautiful specimen, in the American hangar.
 
8670392119_ae647bc943.jpg
 
I spent a good 45+ minutes walking around it taking in (as much as my very amateur eye could) the details. I'd wanted to see one for years, and now I have. The guard/guide let me step over the barrier and get right underneath it to have a closer look. The opening flaps under the fuselage, the main gear flaps I believe, had been signed by a bunch of crew chiefs and the odd pilot. It was a surprisingly emotional experience seeing it in the metal after having watched documentaries and read books.
 
Definitely want to go back and spend another day there. Duxford is spectacular.


#18 275 GTB-4

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Posted 01 October 2013 - 00:27

Discuss. 

 

 

http://youtu.be/_vrvep_YOio

 

Far out man! That's really, ya know, a psychedelic experience man...I could watch it  for hours...cept my eyes get tired from rolling around :rotfl:



#19 bigleagueslider

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Posted 01 October 2013 - 03:27

indigoid-

 

A bit OT, but there is a great story behind how Lockheed obtained the titanium supplies for building the SR-71's.  Don't know if the story is entirely true, but because there was an economic embargo put in place by the US government on import/export of strategic materials/goods with the Soviet Union during the 50's and 60's,  Lockheed could not obtain the supply of titanium metals it needed to build the SR-71.  In order to circumvent the economic embargo, Lockheed purchased the material from the Soviets in the form of titanium shovels.



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#20 desmo

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Posted 01 October 2013 - 04:35

Seems odd if true.  Ti is a relatively common element and they could easily sourced it from other countries if it had been a priority.

 

http://www.alibaba.c...um_Shovels.html



#21 gruntguru

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Posted 01 October 2013 - 06:59

Great link desmo!



#22 Kelpiecross

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Posted 01 October 2013 - 13:12

Seems odd if true.  Ti is a relatively common element and they could easily sourced it from other countries if it had been a priority.
 
http://www.alibaba.c...um_Shovels.html


Are these shovels (and many other garden tools on ebay) made of titanium metal or is "Titanium" a company name? Many of these "titanium" tools say in their descriptions that they have stainless steel or high carbon steel blades. Why would you make a garden tool from titanium metal?

#23 indigoid

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Posted 01 October 2013 - 16:04

Why would you make a garden tool from titanium metal?

 

It doesn't answer the question about possibly-Ti shovels from the Alibaba merchantry, but if you were a player in the colossal US aerospace/defense industry... Why not? You could put them on the same page of the catalog as the $350 ashtrays (designed to not break into more than two pieces if you knock it off your desk onto the floor, because safety**) and $640 toilet seats

 

** but feel free to keep sharing the tobacco smoke with others in the office

 

edit: back on topic, and thinking about the oil problem and supercharged sleeve-valve engines... with a bit of a pressure differential at startup to suck oil into the inlet it might actually help to get things oiled up faster, by leaking a bit of oil around the valve openings into the "outside" surface of the sleeve. Presumably the sleeves would be particularly leaky at startup due to clearances for thermal expansion...


Edited by indigoid, 01 October 2013 - 16:10.


#24 Lee Nicolle

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Posted 01 October 2013 - 23:31

Are these shovels (and many other garden tools on ebay) made of titanium metal or is "Titanium" a company name? Many of these "titanium" tools say in their descriptions that they have stainless steel or high carbon steel blades. Why would you make a garden tool from titanium metal?

My thoughts too. Titanium is a very strong light material that has a reputation for work hardening.And can be brittle. Not the thing to make a shovel from. High carbon steel is infinitly more suited for the job and is lot cheaper, and a lot cheaper to manufacture one would guess.

#25 RogerGraham

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Posted 02 October 2013 - 00:29

Apparently the titanium is used as a coating on an-otherwise steel device: http://www.gardening...ardening-tools/



#26 Wuzak

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Posted 02 October 2013 - 01:41

Is that titanium coating, or titanium-nitride, as is often used on drill bits, end mills and the like?

 

97px-Titanium_nitride_coating.jpg



#27 desmo

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Posted 02 October 2013 - 04:06

The shovels for sale I linked to are I think actually Ti (probably prosaic Russian-standard CP).  The steel ones sold as "Titanium" are probably just steel with a dab of titanium white paint added somewhere inconspicuous to make the claim less risable, I doubt they actually bother to coat them with TiN. Once Ti became a marketing buzzword, the marketers clearly saw their duty to drive it into the ground. And what better vehicle than a shovel?



#28 desmo

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Posted 02 October 2013 - 04:15

I wouldn't be the least surprised to find out the alibaba shovels are NOS from the cold war era when import-export restrictions were in place and this was basically just a form of Ti ingot for export that skirted the regulations until some bureaucrat--Soviet or Western--figured the scam out and shut it down leaving a Russian warehouse somewhere stacked with Ti shovel heads with no market. It's little different than buying a Brazilian Rosewood "table" that is never meant to be used as such--it's just a way to get the lumber out of Brazil in a plausibly legal way to make musical instruments etc. from.



#29 bigleagueslider

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Posted 03 October 2013 - 03:29

Seems odd if true.  Ti is a relatively common element and they could easily sourced it from other countries if it had been a priority.

Titanium metals were not widely available in the early 60's when the SR-71 was being developed.  Most of the SR-71 airframe was made from titanium and there were nowhere near the amount of titanium supplies required available from "friendly" sources.  The Soviet Union was the only source at that time capable of meeting the titanium requirements of Lockheed for the SR-71 program.  The SR-71 was a classified project at that time, and due to the US economic embargo on trade of strategic materials with the Soviets it would have required an act of Congress for Lockheed to legally purchase titanium from the Soviets for manufacturing a defense related product.  However, there was a legal loophole in the embargo that still allowed trade of agricultural goods with the Soviets, so Lockheed placed an order for thousands of titanium "shovels" with Soviet manufacturers.



#30 Lee Nicolle

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Posted 03 October 2013 - 22:52

Titanium metals were not widely available in the early 60's when the SR-71 was being developed.  Most of the SR-71 airframe was made from titanium and there were nowhere near the amount of titanium supplies required available from "friendly" sources.  The Soviet Union was the only source at that time capable of meeting the titanium requirements of Lockheed for the SR-71 program.  The SR-71 was a classified project at that time, and due to the US economic embargo on trade of strategic materials with the Soviets it would have required an act of Congress for Lockheed to legally purchase titanium from the Soviets for manufacturing a defense related product.  However, there was a legal loophole in the embargo that still allowed trade of agricultural goods with the Soviets, so Lockheed placed an order for thousands of titanium "shovels" with Soviet manufacturers.

So a deliberate illegal scam! Did they come with hollow handles too filled with other illegal substances, probably from a country ending in 'stan!

#31 Greg Locock

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Posted 03 October 2013 - 23:27

That could have been a self funding exercise.

 

 

Interestingly google puts this thread as the first hit on sr71 "titanium shovels", so I have a feeling it may be a new 'fact'.



#32 Magoo

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Posted 04 October 2013 - 01:42

That could have been a self funding exercise.

 

 

Interestingly google puts this thread as the first hit on sr71 "titanium shovels", so I have a feeling it may be a new 'fact'.

 

I discovered the same thing -- not very confidence inspiring. The story sure does sound apocryphal. If there is a primary source I'd love to see it. 



#33 Catalina Park

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Posted 04 October 2013 - 08:47

Probably a story put out by the bloke with a shed full of unsold titanium shovels.



#34 Magoo

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Posted 04 October 2013 - 11:20

What is a ti shovel for, anyway? I'd throw it 40 feet behind me first time I used it. 



#35 bigleagueslider

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Posted 05 October 2013 - 04:13

I discovered the same thing -- not very confidence inspiring. The story sure does sound apocryphal. If there is a primary source I'd love to see it. 

The original version of the SR-71 was the A-12.  The A-12 was a CIA program.



#36 Catalina Park

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Posted 05 October 2013 - 04:22

What is a ti shovel for, anyway? I'd throw it 40 feet behind me first time I used it. 

The only advantage I can see is reduced transport costs.



#37 malbear

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Posted 05 October 2013 - 10:29

What is a ti shovel for, anyway? I'd throw it 40 feet behind me first time I used it. 

A light shovel is only good for shifting grain if it is large enough . you need a bit of weight to shift gravel for concrete work. or dirt while fencing



#38 MatsNorway

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Posted 05 October 2013 - 11:48

Might be a thing for space programs in the future. But to be fair a aluminium shovel who has been given a thermal spraying is probably superior. It So i don`t see a thing for it anywhere. Unless a chemical plant where steel and alu shovel might react with some material your working with. In general no. Just no.



#39 Magoo

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Posted 05 October 2013 - 12:27

The original version of the SR-71 was the A-12.  The A-12 was a CIA program.

 

No, this is where you were going to post a primary source. 



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#40 desmo

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Posted 05 October 2013 - 15:04

http://www.blackbird...cessortou2.html

 

Hmmm, didn't know about the cesium fuel additive to reduce "radar cross section of the afterburner plume".



#41 Lee Nicolle

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Posted 06 October 2013 - 01:03

The only advantage I can see is reduced transport costs.[/size]

The cubic measure would defeat that anyway

#42 Lee Nicolle

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Posted 06 October 2013 - 01:06

A light shovel is only good for shifting grain if it is large enough . you need a bit of weight to shift gravel for concrete work. or dirt while fencing

Even for grain a good steel shovel feels better. And too me that is a terrible job, sand is a whole lot cleaner.

#43 gruntguru

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Posted 06 October 2013 - 20:19

I recall using aluminium shovels in a flammable environment (empty fuel storage tanks) because steel shovels create sparks. From what I have seen of Ti golf clubs (sparks on contact with the ground - easily visible at night) the Ti shovel would be deadly.



#44 malbear

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Posted 06 October 2013 - 21:40

I recall using aluminium shovels in a flammable environment (empty fuel storage tanks) because steel shovels create sparks. From what I have seen of Ti golf clubs (sparks on contact with the ground - easily visible at night) the Ti shovel would be deadly.

sorry for harping on shovels but I am decended from good cornish copper mining stock :wave: Is there such a thing as a bronze shovel ? heavier than steel and no sparks.



#45 Magoo

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Posted 06 October 2013 - 21:49

I  have a flat-bladed aluminum coal scoop I use to shovel snow. I try not to scrape the edge on the pavement too much and wear it out quickly. 

 

Other than that, I use steel. A few years ago I looked at a garden shovel in the home garage and realized it was worn out, needed replacement. The blade and the handle were shot. Funny, because I remembered buying it new -- Stanley, a good one. That got me to thinking. When you've lived long enough to wear out a garden shovel, that's pretty goddamned old. 



#46 malbear

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Posted 06 October 2013 - 22:17

back onto the subject I read somewhere that the Lockheed fuel tanks would leak while on the ground but seal up during flight as the titanium heated up. I wonder if the cesium fuel additive acted as a cloud seeding agent telling the rushkys that the flight had occured. I gues that the rational was that the fallout was over russia and that didnt matter.



#47 Greg Locock

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Posted 07 October 2013 - 01:15

If you google around on SR71 and Mary Shafer you'll get many true sounding tales about her experiences with operating the things for NASA. There's also lots of pilot's stories which lack quite the same truthiness.



#48 Lee Nicolle

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Posted 07 October 2013 - 02:48

I have seen doccos on the Stealth bomber/ spyplane and they did leak/ weep on the ground but sealed up in flight. Reportedly the fuel is so 'weak' it is not flammable to a naked flame. It does not inspire confidence though.

#49 Greg Locock

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Posted 07 October 2013 - 03:42

http://yarchive.net/air/sr71.html



#50 bigleagueslider

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Posted 07 October 2013 - 04:00

No, this is where you were going to post a primary source. 

 

Magoo,

 

Here is what I said in my original post:

 

"A bit OT, but there is a great story behind how Lockheed obtained the titanium supplies for building the SR-71's.  Don't know if the story is entirely true, but because there was an economic embargo put in place by the US government on import/export of strategic materials/goods with the Soviet Union during the 50's and 60's,  Lockheed could not obtain the supply of titanium metals it needed to build the SR-71.  In order to circumvent the economic embargo, Lockheed purchased the material from the Soviets in the form of titanium shovels."

 

I said it was just a great story I had heard, and did not claim to know if it was entirely true.  There are numerous public sources that will confirm the fact that much of the titanium used for SR-71 production came from the Soviets and was procured through "unconventional" means.  It does not require a huge leap of faith to believe the story might have some factual basis.

 

Sorry that I can't give you with a bonafied "primary source" that provides irrefutable proof of the veracity of historical events I described as being a "story I had heard" regarding the source of some of the titanium used to manufacture the Lockheed SR-71 airframes.  I'm sure you'd agree that this request would be just as silly as me demanding that you provide a "primary source" confirming that your name is really Magoo.