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RAF announces Puma Replacement plan

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RAF announces Puma Replacement plan

Old 12th Mar 2023, 18:27
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SAS, the quoted article history wise is pretty much accurate as to the process the Army employed to arrive at design requirements, but it has one absolute error of substance and another, huge error of missing but critical information re flyoff results.

The error of substance relates to the performance shortcoming quoted for the YUH-60A. That shortcoming was actually true early in development, but remedied prior to the fly-off. I can’t recall if the last main blade change we made, to extend the tip cap to meet the hover and climb performance requirement ( which it did ), was on the ship when the Army did their preliminary evaluation in Sept/Oct 1975. In any case, it was on all of the ships for the fly-off, and that blade configuration was unchanged, going to production.*

During the operational evaluation part of the fly-off, two events occurred which indicated that the Sikorsky prototype possessed an approximate 2000 lb hover performance advantage over the Boeing model. One at FT. Rucker, Shell Field and one at FT. Campbell, op eval site.

1. FT. Rucker. Shell Field. Each competitor had to train/qualify 10 Army pilots to perform the op eval test program. Part of that syllabus was of course external sling loads. On the day in question, Sikorsky was up first. The Army had prepared seven 55 gal. drums full of concrete/iron which weighed 1000 lbs and had an attachment built in. They also supplied a collector cable , enabling the carry of one thru seven drums. We started with seven, picked up the seven, climbed away vertically and did the same for all ten trainees with I think 2 refuelings during the morning.

Boeing then started, also with seven drums. But they couldn’t budge the seven, so they unhooked one and tried that. Couldn’t pick up 6000 either. Unhooked another drum. Now at 5000 lbs the YUH-61 finally got that load airborne, to maybe 3-4 ft. Then in order to get going, trundled along not gaining any altitude until they got to 20 kts or so and then started climbing. I watched this from about 40 yards away. Note: the Boeing main rotor diameter was I believe 48 ft whereas the Sikorsky main rotor was 53’8”.

2. Ft. Campbell. The Army has a new infantry vehicle called the Gamma Goat, which weighed 7100 lbs and they were anxious to see that the UH-1 replacement could carry it. The op eval was now under way and all the flying was done by the trained Army pilots. Sikorsky was first and, with full fuel and standard crew and field configuration ( which is to say, all seats etc. ) picked up the Goat climbed out, flew a pattern and landed it where it had been. The Boeing YUH-61 did the same thing except that the ship had only 400 lbs of fuel, no troop seats and minimum radio gear. Following their landing of the Goat, they went to the fuel farm to refuel. This was reported in detail by one of the Army maintenance test pilots assigned to the program ( two were assigned and each had been trained by the respective contractor at FT. Rucker ).

*The article makes no mention of the hover performance difference, NOR, that the Boeing Production Proposal for the YUH-61 included larger rotors.

Maintenance Differences. Can’t comment on the data in the article, but can add this fact: During the op eval period at Ft Rucker, the Army maintenance troops working the Boeing machines worked every weekend, while the troops working on the Sikorsky ships did not have to work one weekend.

Enough re the flyoff.

With re to the question of design features requirements for an aircraft that operates in harms way, there are several requirements that applied to both the UTTAS and AAH programs ( and two interesting ones that were on the Sikorsky UH-60 but not the AH-64 ).

Crashworthiness. The experiences in Vietnam led to the development of a Helicopter Mil Standard for Crash Resistance 1290. There is a Table 1 which defines the survivable crash conditions and it starts with a vertical impact at 42 ft/sec ( fixed landing gear ) and includes longitudinal, lateral and combined axes. In another section, it addresses the Engines transmission and rotor heads, requiring that these need to remain in place, so as not to hazardous to occupants under a crash condition of 20G vertically, 20G longitudinally and 18G laterally. Fuel systems shall be designed to contain fuel under the conditions in Table 1. Doesn’t allow leaks.

Anecdote: In order to prove compliance with 1290, we had to build a copy of the tank enclosure structure containing the main fuel tank and associated valves, fill the tank and drop it from 65 ft-no leaks. I have seen a picture of an AH-64 crash where the tank was ripped out of the aircraft and sitting on the ground apart from the wreckage-no leaks.

Ballistic Tolerance. As I recall and simply stated, the UTTAS was required to be invulnerable to 7.62 caliber weapons, the control system up to 51 caliber weapons and the blades to 23mm HEI. Components, including the blades ( and redone with the composite blades ) were subject to live fire tests.

I mentioned two items which were not required but were installed on each new UH-60A.
  • · The AFCS computer incorporated a separate chip which was in effect a flight data recorder. Not crash or fire proof, but better than nothing. This was the brainchild of the Chief of the Electronic Flight controls group. No cost.
  • · A tail rotor control quadrant, which was actually a mechanism located at the input to the tail rotor primary servo, with a very strong spring such that if either of the input cables lost tension for whatever reason, the pilot will retain directional control by flying the functioning cable against the spring. Wasn’t required but it went in. Saved one Turkish Hawk that I know of.
So, in the discussion regarding " making do " with off the shelf civil aircraft to handle an admin mission, but " might " in exigent circumstances be drafted into tactical use, there are huge differences. The other aspect is that I've read that this or that model helicopter is a " military version ". Get them to show you the evidence.
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Old 12th Mar 2023, 19:36
  #322 (permalink)  
 
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"So, in the discussion regarding " making do " with off the shelf civil aircraft to handle an admin mission, but " might " in exigent circumstances be drafted into tactical use, there are huge differences. The other aspect is that I've read that this or that model helicopter is a " military version ". Get them to show you the evidence".[/QUOTE]

It's painted green, what more do you need.
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Old 12th Mar 2023, 19:51
  #323 (permalink)  
 
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John - that star quadrant feature was adopted in the 76 too.
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Old 12th Mar 2023, 22:35
  #324 (permalink)  
 
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Originally Posted by JohnDixson
SAS, the quoted article history wise is pretty much accurate as to the process the Army employed to arrive at design requirements, but it has one absolute error of substance and another, huge error of missing but critical information re flyoff results.

The error of substance relates to the performance shortcoming quoted for the YUH-60A. That shortcoming was actually true early in development, but remedied prior to the fly-off. I can’t recall if the last main blade change we made, to extend the tip cap to meet the hover and climb performance requirement ( which it did ), was on the ship when the Army did their preliminary evaluation in Sept/Oct 1975. In any case, it was on all of the ships for the fly-off, and that blade configuration was unchanged, going to production.*

During the operational evaluation part of the fly-off, two events occurred which indicated that the Sikorsky prototype possessed an approximate 2000 lb hover performance advantage over the Boeing model. One at FT. Rucker, Shell Field and one at FT. Campbell, op eval site.

1. FT. Rucker. Shell Field. Each competitor had to train/qualify 10 Army pilots to perform the op eval test program. Part of that syllabus was of course external sling loads. On the day in question, Sikorsky was up first. The Army had prepared seven 55 gal. drums full of concrete/iron which weighed 1000 lbs and had an attachment built in. They also supplied a collector cable , enabling the carry of one thru seven drums. We started with seven, picked up the seven, climbed away vertically and did the same for all ten trainees with I think 2 refuelings during the morning.

Boeing then started, also with seven drums. But they couldn’t budge the seven, so they unhooked one and tried that. Couldn’t pick up 6000 either. Unhooked another drum. Now at 5000 lbs the YUH-61 finally got that load airborne, to maybe 3-4 ft. Then in order to get going, trundled along not gaining any altitude until they got to 20 kts or so and then started climbing. I watched this from about 40 yards away. Note: the Boeing main rotor diameter was I believe 48 ft whereas the Sikorsky main rotor was 53’8”.

2. Ft. Campbell. The Army has a new infantry vehicle called the Gamma Goat, which weighed 7100 lbs and they were anxious to see that the UH-1 replacement could carry it. The op eval was now under way and all the flying was done by the trained Army pilots. Sikorsky was first and, with full fuel and standard crew and field configuration ( which is to say, all seats etc. ) picked up the Goat climbed out, flew a pattern and landed it where it had been. The Boeing YUH-61 did the same thing except that the ship had only 400 lbs of fuel, no troop seats and minimum radio gear. Following their landing of the Goat, they went to the fuel farm to refuel. This was reported in detail by one of the Army maintenance test pilots assigned to the program ( two were assigned and each had been trained by the respective contractor at FT. Rucker ).

*The article makes no mention of the hover performance difference, NOR, that the Boeing Production Proposal for the YUH-61 included larger rotors.

Maintenance Differences. Can’t comment on the data in the article, but can add this fact: During the op eval period at Ft Rucker, the Army maintenance troops working the Boeing machines worked every weekend, while the troops working on the Sikorsky ships did not have to work one weekend.

Enough re the flyoff.

With re to the question of design features requirements for an aircraft that operates in harms way, there are several requirements that applied to both the UTTAS and AAH programs ( and two interesting ones that were on the Sikorsky UH-60 but not the AH-64 ).

Crashworthiness. The experiences in Vietnam led to the development of a Helicopter Mil Standard for Crash Resistance 1290. There is a Table 1 which defines the survivable crash conditions and it starts with a vertical impact at 42 ft/sec ( fixed landing gear ) and includes longitudinal, lateral and combined axes. In another section, it addresses the Engines transmission and rotor heads, requiring that these need to remain in place, so as not to hazardous to occupants under a crash condition of 20G vertically, 20G longitudinally and 18G laterally. Fuel systems shall be designed to contain fuel under the conditions in Table 1. Doesn’t allow leaks.

Anecdote: In order to prove compliance with 1290, we had to build a copy of the tank enclosure structure containing the main fuel tank and associated valves, fill the tank and drop it from 65 ft-no leaks. I have seen a picture of an AH-64 crash where the tank was ripped out of the aircraft and sitting on the ground apart from the wreckage-no leaks.

Ballistic Tolerance. As I recall and simply stated, the UTTAS was required to be invulnerable to 7.62 caliber weapons, the control system up to 51 caliber weapons and the blades to 23mm HEI. Components, including the blades ( and redone with the composite blades ) were subject to live fire tests.

I mentioned two items which were not required but were installed on each new UH-60A.
  • · The AFCS computer incorporated a separate chip which was in effect a flight data recorder. Not crash or fire proof, but better than nothing. This was the brainchild of the Chief of the Electronic Flight controls group. No cost.
  • · A tail rotor control quadrant, which was actually a mechanism located at the input to the tail rotor primary servo, with a very strong spring such that if either of the input cables lost tension for whatever reason, the pilot will retain directional control by flying the functioning cable against the spring. Wasn’t required but it went in. Saved one Turkish Hawk that I know of.
So, in the discussion regarding " making do " with off the shelf civil aircraft to handle an admin mission, but " might " in exigent circumstances be drafted into tactical use, there are huge differences. The other aspect is that I've read that this or that model helicopter is a " military version ". Get them to show you the evidence.
if “the United States of Europe” would put in an order of say 2500 H175m or AW149s I am sure either Airbus or Leonardo will provide the same or better service/quality than either Boeing or Sikorsky provided. 😉👍 As this will not happen you either have to make do with what you get or order an old American design.
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Old 13th Mar 2023, 01:17
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Eric-yep, it seems like that’s enough.
212-right-just saying that the S-70 was first with Dean Cooper’s design.
Casper-yes-you know it is interesting that, at least from what makes the press, air mobile warfare tactics have been left at home In the Ukraine. To your other point it would appear that neither Airbus nor AW have bought into the concepts of crashworthiness or ballistic tolerance for military vertical lift aircraft? It is a trade, with cost, weight,performance factors in the balance.
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Old 13th Mar 2023, 10:15
  #326 (permalink)  
 
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Originally Posted by casper64
if “the United States of Europe” would put in an order of say 2500 H175m or AW149s I am sure either Airbus or Leonardo will provide the same or better service/quality than either Boeing or Sikorsky provided. 😉👍 As this will not happen you either have to make do with what you get or order an old battle proven American design.
There, changed that for you Casper
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Old 13th Mar 2023, 10:42
  #327 (permalink)  

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John, during my days on the S-70 I was tasked to lift a generator in the aftermath of a typhoon, which had caused a major landslide and the loss of a road and the mains electricity cables below it. The generator weighed a fraction under 9,000 lbs. Our aircraft had the 9,000 lb hook, so I agreed. Although I’d lifted many lighter loads before, as we lifted to the hover to pick it up and took the strain there was absolutely no mistaking where that load was sitting on the ground. All I had to do was keep pulling power and the aircraft and load just lined themselves up!

The task was to position the generator on a narrow path on a steep hillside. Unfortunately, that meant approaching in an adverse wind. The aircraft did the job with some power to spare.

Bizarrely, believe it or not, that was how I helped save the life of a killer whale.


If I had to go to war in any helicopter, I’d prefer to do it in that type.
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Old 13th Mar 2023, 12:22
  #328 (permalink)  
 
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I’m intrigued by the Blackhawk ballistic tolerance - unaffected by 7.62? That’s the equivalent of B6 (European standard). Having been in a number of B6 vehicles I struggle to imagine a helicopter offering the same protection.

I’m not contradicting the statement, just curious!
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Old 13th Mar 2023, 13:07
  #329 (permalink)  

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Originally Posted by 212man
I’m intrigued by the Blackhawk ballistic tolerance - unaffected by 7.62? That’s the equivalent of B6 (European standard). Having been in a number of B6 vehicles I struggle to imagine a helicopter offering the same protection.

I’m not contradicting the statement, just curious!
They never claimed that 7.62 bounce off!
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Old 13th Mar 2023, 13:21
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Originally Posted by ShyTorque
They never claimed that 7.62 bounce off!
I was basing my comment on John’s post
Ballistic Tolerance. As I recall and simply stated, the UTTAS was required to be invulnerable to 7.62 caliber
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Old 13th Mar 2023, 14:38
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212,

I went to War in Huey's and Chinooks....neither were built to the later UTTAS Spec....and we saw the results.

Those lessons were what was the driver behind that new Spec.

In doing a small research project re the ways my Army Flight School Classmates died in Vietnam....the words "burns", "burned", "post crash fire", "caught fire and crashed" figured way too often.

One example of sensitive a helicopter can be to a single 7.62 round can be.....on the Chinook each flight control Servo (Jack) on each rotor head has two hydraulic lines separated by armor plate to prevent both lines being severed with a single bullet.

An aircraft in my unit....took several hits to include one round the severed on of the lines a Servo and dented the other.....had not that armor plate been there we would have lost an aircraft, the five man crew, and the twenty odd passengers.

That demonstrated the value of armor but also difficulties in determining what the design should be to afford sufficient protection.

Protection of systems comes not only from the installation of armor (with serious weight being added) to something as simple as the way hydraulic lines and other systems components are routed and installed which adds much less weight.

One look at a Blackhawk rotor head and push pull tubes and all of the lugs they are connected to....compared to a Huey and you can see immediately what the difference is due to the Spec.

The Blackhawk fuel tank drop test that had to be met is probably the most telling difference between the Huey Spec and the BlackHawk Spec.

I can offer first commentary on what the results of being hit by 7.62 and .51 Caliber rounds can be and what some of the results can be.

The Army and Sikorsky spec'd, designed, tested, and fielded a first class combat helicopter in the UH-60 Blackhawk.....and have improved that design since its first days.

I love the Huey....and after flying. other helicopters I described my late flying in the Huey as being like dancing with an old Girl Friend.

If I were to have to go to War again....my choice of horses would not be anything else but the Blackhawk if the choices were the same candidates the MoD is looking at to replace the Puma.
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Old 13th Mar 2023, 15:50
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We were first hoping for Blackhawks to replace our Pumas in the early 1980s. Forty years on, any day now….
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Old 13th Mar 2023, 17:33
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212-meant to be able to continue flying, i.e., not brought down.
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Old 13th Mar 2023, 17:35
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It was always my understanding that the BlackHawk’s ballistic requirement were the capability to fly safely for 1/2 hour after flight critical controls had been hit by a 23mm high-explosive incendiary projectile, and that includes the MRH, Hub, Blades and MGB.

Not something I suspect the ‘Commercial' contenders have even thought about, let alone certified.

I say commercial, as even the AW149 is an AW139 (EASA JAR/CS-29 certified commercial airframe), with a 90 to 100cm cabin stretch, is it not?

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Old 13th Mar 2023, 17:47
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Originally Posted by Hilife
as even the AW149 is an AW139 (EASA JAR/CS-29 certified commercial airframe), with a 90 to 100cm cabin stretch, is it not?
No the AW149 is the military version of the AW189 which is not an extended AW139, some systems similar but has different engines (CT72E) and other different systems installed compared with the AW139
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Old 13th Mar 2023, 17:58
  #336 (permalink)  
 
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Originally Posted by finalchecksplease
No the AW149 is the military version of the AW189 which is not an extended AW139, some systems similar but has different engines (CT72E) and other different systems installed compared with the AW139
Other way round actually, the 189 is the civilian derivative of the 149. I know LH will use hype, as much as any contender, but they do seem adamant that they certified against DEFStan 00-970

ttps://www.gradcracker.com/hub/679/leonardo/blogs/4123/aw149-designed-to-survive-on-the-modern-battlefield-part-1
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Old 13th Mar 2023, 18:22
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SAS, Shy and other former Army pilots: there is one non Sikorsky person who owns responsibility for a lot of the stiff requirements that went into writing the required specs for the UTTAS ( and AAH for that matter ). There was a group formed around 1968 or so and the officer in command was a former Vietnam pilot, Lt. Col Clarence ( Bud ) Patnode. He has a collection of stories about the arguments: wheels vs skids, one vs two engines, icing flight required or not, how to spec out preventing the head and main box from falling into the cabin/cockpit in a crash, how to spec out the fuel system safety and prevent flamers etc etc. There was a large and influential group of officers who thought that what was needed was simply a larger, bigger- engined Huey on skids. That he was able to come up with the Material Need Document , defend it and see it thru approval at Chief of Staff level is testimony to his abilities. He retired an O-6 and resides in Utah.
One early indicator of the excellence of his work is that during the UTTAS development period and fly-off, that specification did not change.
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Old 13th Mar 2023, 18:29
  #338 (permalink)  
 
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Originally Posted by JohnDixson
SAS, Shy and other former Army pilots: there is one non Sikorsky person who owns responsibility for a lot of the stiff requirements that went into writing the required specs for the UTTAS ( and AAH for that matter ). There was a group formed around 1968 or so and the officer in command was a former Vietnam pilot, Lt. Col Clarence ( Bud ) Patnode. He has a collection of stories about the arguments: wheels vs skids, one vs two engines, icing flight required or not, how to spec out preventing the head and main box from falling into the cabin/cockpit in a crash, how to spec out the fuel system safety and prevent flamers etc etc. There was a large and influential group of officers who thought that what was needed was simply a larger, bigger- engined Huey on skids. That he was able to come up with the Material Need Document , defend it and see it thru approval at Chief of Staff level is testimony to his abilities. He retired an O-6 and resides in Utah.
One early indicator of the excellence of his work is that during the UTTAS development period and fly-off, that specification did not change.
Interesting career! https://airandspace.si.edu/support/w...ode-jr-usa-ret
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Old 13th Mar 2023, 20:09
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SAS, Shy and other former Army pilots:
Army? ‘Scuse me, John!
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Old 13th Mar 2023, 23:03
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Sorry Shy-just thought you were. Remembering the Day I joined Sikorsky there were only three former Army guys, and it was a great education being exposed to the other service guys experiences at personal level. The cross service humor was there occasionally, but in reality, one quickly realized that each service had its strengths and not so hot areas. 1966 and there were a few WWII and Korea folks, too.
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