No cats and flaps ...... back to F35B?
New delay over fighter jet choice - Telegraph
You put your STOVL in, you take your STOVL out
You whip out your Catobar and shake it all about
Can we get some
ing adult supervision around here?
/weeps softly, bangs head on desk
Actually, what this looks like is a retaliatory leak for the Stackley letter leak.
You put your STOVL in, you take your STOVL out
You whip out your Catobar and shake it all about
Can we get some
ing adult supervision around here?/weeps softly, bangs head on desk
Actually, what this looks like is a retaliatory leak for the Stackley letter leak.
I don't have any pearls of wisdom or insider knowledge to offer here so forgive me while I vent my spleen in a possibly-uninformed way...
How on earth can converting the carriers to CATOBAR cost £2bn? The possibility of converting the carriers at a later stage in their life had been discussed several years ago, so one would think there would have been at least a 'nod' to possible conversion in the basic design. Given that a whole Type 45 destroyer costs 'only' £1bn all-in - and the biggest liners in the world come in around the £0.75bn mark - the £2bn quote is a outrage. If it is true, then BAE should be ashamed of themselves for taking such ridiculous advantage of their captive market - some degree of premium is inevitable but this is just obscene! If this is the price of having an "indigenous defence capability" then I'm not entirely convinced it's worth it... 
Rant over.
How on earth can converting the carriers to CATOBAR cost £2bn? The possibility of converting the carriers at a later stage in their life had been discussed several years ago, so one would think there would have been at least a 'nod' to possible conversion in the basic design. Given that a whole Type 45 destroyer costs 'only' £1bn all-in - and the biggest liners in the world come in around the £0.75bn mark - the £2bn quote is a
outrage. If it is true, then BAE should be ashamed of themselves for taking such ridiculous advantage of their captive market - some degree of premium is inevitable but this is just obscene! If this is the price of having an "indigenous defence capability" then I'm not entirely convinced it's worth it... Rant over.
The latest headline on the Telegraph website says that "Defence Chiefs" are the ones in favour of reverting to the F35B and simply because of the cost of converting the carriers. This seems odd to me, I would have thought the professional opinion would have been full y in favour of the F35C, for all the obvious reasons. This whole F35 saga is really developing into the greatest defence procurement fiasco since the MRA4.
FB
FB
According to Boffin, it's not GBP2 billion... The problem is the absence of a good estimate, which is allowing those who want to stampede the decision-makers to make up their own.
Also missing is any serious evaluation of the through-life cost of Bs and Cs. The B can't help being more expensive to maintain, on account of its many extra moving parts, but then you may need more training cats/traps with the C.
I say "may" because automated carrier landing is already being demoed with some success and will (or at least should) be standard, well within the lifetime of QEC and JSF,
Also missing is any serious evaluation of the through-life cost of Bs and Cs. The B can't help being more expensive to maintain, on account of its many extra moving parts, but then you may need more training cats/traps with the C.
I say "may" because automated carrier landing is already being demoed with some success and will (or at least should) be standard, well within the lifetime of QEC and JSF,
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F-35C CVF Approach Criteria
Nice Su NITKA pic 'kbrockman' - thanks. A lot more 'carrier landing' info can be found from an URL in a previous entry on this thread.
F-35C carrier approach info: VX-23 'Salty Dogs' Joint Strike Fighter Update -LCDR Ken “Stubby” Sterbenz VX-23 Ship Suitability Department Head in Paddles Monthly - Sept 2010
http://www.hrana.org/documents/Paddl...tember2010.pdf (1.3Mb)
"The F-35C is 51.5 ft long and has a wingspan of 43 ft and 668 ft2 of wing area (7 ft longer wingspan and 208ft2 more wing area than the Air force or Marine versions.) It also carries 19,800 lbs of internal fuel - 1000 pounds more gas then the Air Force version. It is powered by a Pratt and Whitney F135 engine that produces 28k lbs and 43k lb of thrust in MIL and AB respectively. The max trap weight will be around 46k lbs, with an empty weight of about 35k lbs. It will fly an on-speed AOA of 12.3° at 135-140 KCAS [Optimum Angle of Attack or Donut]...."
____________
Some info from the F-35C 'drop testing':
Lightning shock: key.Aero, Military Aviation
“…The tests were successfully carried out between March and April [2010], and included dropping CG-01 95 inches at 20 feet per second, with an 8.8 deg pitch [near Optimum AoA 12.3], two degree roll, and 133 knot wheel speed, simulating a carrier-deck landing.…”
Perhaps from this information some approach conditions to CVF can be inferred - at NIL WOD for CVF but even knowing 'wheel speed' from above link it is not known if this is the maximum wheel speed for a carrier landing. We know I believe that the runway wheel speed is much higher for takeoff while F-35A landing speed is said to be 25 KIAS higher than F-35C approach speed (with a flare reducing final touch down speed for A model : The Joint Strike Fighter: A plane for all reasons | Machine Design)) but how that applies to a carrier landing given the other unknowns about the capacity of the arrestor gear (weight of aircraft and engaging speed limits) I'll just have to scratch my nose.
_______________
Some more grist for the mill with a higher landing speed mentioned:
Vought Test Lab Performs Series of Drop Tests on F-35C for LM
"...This “drop test” is done to simulate a landing on an aircraft carrier. As a fighter jet approaches the deck of a carrier, forty-six thousand pounds of airplane is traveling at 138 knots and hitting the deck with a thud, stressing the airframe and especially the jet’s landing Vought Test Lab Simulates Jet Landing on an Aircraft Carrier gear with thousands of pounds of pressure. Every part of the gear must withstand that tremendous stress time after time with no structural failure...."
_____________________
JSF Carrier Variant Meets First Flight Goals Jun 8, 2010 By Graham Warwick
JSF Carrier Variant Meets First Flight Goals | AVIATION WEEK
“Handling with landing gear down was a key focus of the first flight as the F-35C has a 30% larger wing and uprated flight controls to reduce takeoff and landing speeds compared with the other F-35 variants. Knowles says the aircraft approached at 135 kt., compared with 155 kt. for the smaller-winged F-35A and B variants at the same 40,000-lb. gross weight. Takeoff rotation speed was 15-20 kt. slower, he says...."
_______________________
From the above my back of envelope calculations are: CVF at 10 knots in NIL wind can arrest at Maximum Landing Weight F-35C at Opt. Angle of Attack Approach (140- KIAS) within limits of the USN Mk.7 Mod 3 or better Arresting Gear (I'll presume that the new Advanced Arresting Gear - AAG has better capability). LANDING SIGNAL OFFICER REFERENCE MANUAL (REV. B) with Arrest Gear Stats here: http://63.192.133.13/VMF-312/LSO.pdf [no longer available] OR [will advise of new location when found]
OR USN Mk.7 Arrestor Gear info here:
http://www.globalsecurity.org/milita...lre-a_2002.pdf
NB: The above 'back of postage stamp' calculations did not take into account the speed definitions and factors here: 'REVIEW OF THE CARRIER APPROACH CRITERIA FOR CARRIER-BASED AIRCRAFT PHASE I; FINAL REPORT'
SPEED DEFINITIONS:
http://www.robertheffley.com/docs/HQ...IR_2002_71.pdf
"The relationship between Vpa, WOD, and engaging speed is significant to the discussion of approach requirements. Touchdown speed is defined as 105% of Vpa. The 5% factor added to the touchdown speed is not arbitary. It is based on actual ship survey data and the statistical variation seen in the actual touchdown speeds. The percentage varies with each aircraft. However, for design purposes, a 5% factor is used as a nominal value to define touchdown speed. Engaging speed is defined as touchdown speed minus WOD. Closure speed is the relative speed between the aircraft and the ship. The engaging speed limit is the minimum of the arresting gear limit speed, hookload limit speed, or limiting sink speed. The engaging speed must not exceed the engaging limit speed for safe recovery. WOD is generated by the combination of natural wind and/or ship speed.
+ [from diagram in PDF]
Engaging Speed Factor (0.06 x Approach Speed)"
_______________
For various 'speed' definitions and other assortments:
REVIEW OF THE CARRIER APPROACH CRITERIA FOR CARRIER-BASED AIRCRAFT PHASE I; FINAL REPORT
http://www.robertheffley.com/docs/HQ...IR_2002_71.pdf
There are adverse effects if the 'ideal' WOD is not achieved with too much Wind Over the Deck having unintended consequences. Info on this aspect here: Effect of Wind Over Deck Conditions on Aircraft Approach Speeds for Carrier Landings 1991
http://www.dtic.mil/cgi-bin/GetTRDoc...f&AD=ADA239511
_______________________
F-35B Key Performance Parameter - KPP conditions (not certain if current because the distance has recently been increased from 550 to 600 feet on a flat deck):
"The USMC has added STOVL performance as a service specific key performance parameter. The requirement is listed as follows: With two 1000# JDAMs and two internal AIM-120s, full expendables, execute a 550 foot (450 UK STOVL) STO from LHA, LHD, and aircraft carriers (sea level, tropical day, 10 kts operational WOD) and with a combat radius of 450 nm (STOVL profile). Also must perform STOVL vertical landing with two 1000# JDAMs and two internal AIM-120s, full expendables, and fuel to fly the STOVL Recovery profile."
Download a 0.4Mb PDF here: Scorecard: A Case study of the Joint Strike Fighter Program by Geoffrey P. Bowman, LCDR, USN — 2008 April
http://www.f-16.net/f-16_forum_download-id-14791.html
F-35C carrier approach info: VX-23 'Salty Dogs' Joint Strike Fighter Update -LCDR Ken “Stubby” Sterbenz VX-23 Ship Suitability Department Head in Paddles Monthly - Sept 2010
http://www.hrana.org/documents/Paddl...tember2010.pdf (1.3Mb)
"The F-35C is 51.5 ft long and has a wingspan of 43 ft and 668 ft2 of wing area (7 ft longer wingspan and 208ft2 more wing area than the Air force or Marine versions.) It also carries 19,800 lbs of internal fuel - 1000 pounds more gas then the Air Force version. It is powered by a Pratt and Whitney F135 engine that produces 28k lbs and 43k lb of thrust in MIL and AB respectively. The max trap weight will be around 46k lbs, with an empty weight of about 35k lbs. It will fly an on-speed AOA of 12.3° at 135-140 KCAS [Optimum Angle of Attack or Donut]...."
____________
Some info from the F-35C 'drop testing':
Lightning shock: key.Aero, Military Aviation
“…The tests were successfully carried out between March and April [2010], and included dropping CG-01 95 inches at 20 feet per second, with an 8.8 deg pitch [near Optimum AoA 12.3], two degree roll, and 133 knot wheel speed, simulating a carrier-deck landing.…”
Perhaps from this information some approach conditions to CVF can be inferred - at NIL WOD for CVF but even knowing 'wheel speed' from above link it is not known if this is the maximum wheel speed for a carrier landing. We know I believe that the runway wheel speed is much higher for takeoff while F-35A landing speed is said to be 25 KIAS higher than F-35C approach speed (with a flare reducing final touch down speed for A model : The Joint Strike Fighter: A plane for all reasons | Machine Design)) but how that applies to a carrier landing given the other unknowns about the capacity of the arrestor gear (weight of aircraft and engaging speed limits) I'll just have to scratch my nose.
_______________
Some more grist for the mill with a higher landing speed mentioned:
Vought Test Lab Performs Series of Drop Tests on F-35C for LM
"...This “drop test” is done to simulate a landing on an aircraft carrier. As a fighter jet approaches the deck of a carrier, forty-six thousand pounds of airplane is traveling at 138 knots and hitting the deck with a thud, stressing the airframe and especially the jet’s landing Vought Test Lab Simulates Jet Landing on an Aircraft Carrier gear with thousands of pounds of pressure. Every part of the gear must withstand that tremendous stress time after time with no structural failure...."
_____________________
JSF Carrier Variant Meets First Flight Goals Jun 8, 2010 By Graham Warwick
JSF Carrier Variant Meets First Flight Goals | AVIATION WEEK
“Handling with landing gear down was a key focus of the first flight as the F-35C has a 30% larger wing and uprated flight controls to reduce takeoff and landing speeds compared with the other F-35 variants. Knowles says the aircraft approached at 135 kt., compared with 155 kt. for the smaller-winged F-35A and B variants at the same 40,000-lb. gross weight. Takeoff rotation speed was 15-20 kt. slower, he says...."
_______________________
From the above my back of envelope calculations are: CVF at 10 knots in NIL wind can arrest at Maximum Landing Weight F-35C at Opt. Angle of Attack Approach (140- KIAS) within limits of the USN Mk.7 Mod 3 or better Arresting Gear (I'll presume that the new Advanced Arresting Gear - AAG has better capability). LANDING SIGNAL OFFICER REFERENCE MANUAL (REV. B) with Arrest Gear Stats here: http://63.192.133.13/VMF-312/LSO.pdf [no longer available] OR [will advise of new location when found]
OR USN Mk.7 Arrestor Gear info here:
http://www.globalsecurity.org/milita...lre-a_2002.pdf
NB: The above 'back of postage stamp' calculations did not take into account the speed definitions and factors here: 'REVIEW OF THE CARRIER APPROACH CRITERIA FOR CARRIER-BASED AIRCRAFT PHASE I; FINAL REPORT'
SPEED DEFINITIONS:
http://www.robertheffley.com/docs/HQ...IR_2002_71.pdf
"The relationship between Vpa, WOD, and engaging speed is significant to the discussion of approach requirements. Touchdown speed is defined as 105% of Vpa. The 5% factor added to the touchdown speed is not arbitary. It is based on actual ship survey data and the statistical variation seen in the actual touchdown speeds. The percentage varies with each aircraft. However, for design purposes, a 5% factor is used as a nominal value to define touchdown speed. Engaging speed is defined as touchdown speed minus WOD. Closure speed is the relative speed between the aircraft and the ship. The engaging speed limit is the minimum of the arresting gear limit speed, hookload limit speed, or limiting sink speed. The engaging speed must not exceed the engaging limit speed for safe recovery. WOD is generated by the combination of natural wind and/or ship speed.
+ [from diagram in PDF]
Engaging Speed Factor (0.06 x Approach Speed)"
_______________
For various 'speed' definitions and other assortments:
REVIEW OF THE CARRIER APPROACH CRITERIA FOR CARRIER-BASED AIRCRAFT PHASE I; FINAL REPORT
http://www.robertheffley.com/docs/HQ...IR_2002_71.pdf
There are adverse effects if the 'ideal' WOD is not achieved with too much Wind Over the Deck having unintended consequences. Info on this aspect here: Effect of Wind Over Deck Conditions on Aircraft Approach Speeds for Carrier Landings 1991
http://www.dtic.mil/cgi-bin/GetTRDoc...f&AD=ADA239511
_______________________
F-35B Key Performance Parameter - KPP conditions (not certain if current because the distance has recently been increased from 550 to 600 feet on a flat deck):
"The USMC has added STOVL performance as a service specific key performance parameter. The requirement is listed as follows: With two 1000# JDAMs and two internal AIM-120s, full expendables, execute a 550 foot (450 UK STOVL) STO from LHA, LHD, and aircraft carriers (sea level, tropical day, 10 kts operational WOD) and with a combat radius of 450 nm (STOVL profile). Also must perform STOVL vertical landing with two 1000# JDAMs and two internal AIM-120s, full expendables, and fuel to fly the STOVL Recovery profile."
Download a 0.4Mb PDF here: Scorecard: A Case study of the Joint Strike Fighter Program by Geoffrey P. Bowman, LCDR, USN — 2008 April
http://www.f-16.net/f-16_forum_download-id-14791.html
Last edited by SpazSinbad; 25th Mar 2012 at 22:33. Reason: Addition of 'Speed Definition' text + explanation
Having calmed down somewhat from my previous rant, I am struggling to think who in MoD favours the -B over the -C model. Outside the MoD the key STOVL protagonists are presumably the USMC and Rolls-Royce, and possibly BAES if earlier posts are to be believed - but none of these explain why the UK military chain of command appears to be recommending the -B. The only military people I can conceive of preferring the -B model are senior ex-Harrier pilots who might be struggling to let go of their unique selling point.
Surely that is not enough of a reason for all this messing about? Something I heard a long while ago, but dismissed as being too cynical for words, was that the Air Staff preferred F-35B as its shorter range would reduce the radius of influence of the carrier group... please tell me this is indeed too cynical for words, otherwise my despair for the future of our services will get even deeper.
Surely that is not enough of a reason for all this messing about? Something I heard a long while ago, but dismissed as being too cynical for words, was that the Air Staff preferred F-35B as its shorter range would reduce the radius of influence of the carrier group... please tell me this is indeed too cynical for words, otherwise my despair for the future of our services will get even deeper.
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F35B selling points
Like some here said before, the logic for a serviceman to opt for the B over the C seems illogical , most seem to prefer the conventional F35C model over the exotic VTOL B model.
However there must be some advantages to choose the B version, like a famous Dutch soccerplayer once said "every disadvantage has its advantages".
Apart from the apparent advantages of going with VTOL
-Useable on land without a proper runway at hand, close to the frontline.
-no arrestor wire and cat necessary
-looks megacool.
the only other things I could come up with, and I'm not sure if they are true;
-Someone once told me that the launchrate and recover-rate are potentially much higher with a Harrier/F35B like plane.
-The use of improvised carriers is possible at last notice (eg Atlantic conveyor)
-When in trouble , the plane can land pretty much everywhere, on almost any ship large enough or small patch of land, as long as the engine runs
-When needs be, can operate a bid like a helicopter in a dangerous enemy fighter infested airspace, meaning; it can land and hide for a while before reengaging the target/enemy <== okay a bit far fetched, but still a possibility.
-If need be can resuply fuel+weapons not necessaraly alone from carrier but also from any ship with a large enough deck and the right equipment to deliver fuel and weapons.
-possibly a much wider flight envelope, certainly at low and very low speeds.
Are there any other advantages it has (operationally) over the conventional fighters ?
However there must be some advantages to choose the B version, like a famous Dutch soccerplayer once said "every disadvantage has its advantages".
Apart from the apparent advantages of going with VTOL
-Useable on land without a proper runway at hand, close to the frontline.
-no arrestor wire and cat necessary
-looks megacool.
the only other things I could come up with, and I'm not sure if they are true;
-Someone once told me that the launchrate and recover-rate are potentially much higher with a Harrier/F35B like plane.
-The use of improvised carriers is possible at last notice (eg Atlantic conveyor)
-When in trouble , the plane can land pretty much everywhere, on almost any ship large enough or small patch of land, as long as the engine runs
-When needs be, can operate a bid like a helicopter in a dangerous enemy fighter infested airspace, meaning; it can land and hide for a while before reengaging the target/enemy <== okay a bit far fetched, but still a possibility.
-If need be can resuply fuel+weapons not necessaraly alone from carrier but also from any ship with a large enough deck and the right equipment to deliver fuel and weapons.
-possibly a much wider flight envelope, certainly at low and very low speeds.
Are there any other advantages it has (operationally) over the conventional fighters ?
Surely, apart from the reduced range and weapon load, the F35B will carry the lift fan and associated equipment around as dead weight thus hampering performance considerably?
If so, just what was the appeal about it in the first place?
FB
If so, just what was the appeal about it in the first place?
FB
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Conspiracy Theory
Being very cynical and looking for a conspiracy theory (devious senior RAF having over gullible RN again), could the advantage of the F-35B that it will enable the RAF to retain primacy as the aircraft need only pay fleeting visits to the carriers, whereas the F-35C will need them to spend a significantly greater time afloat thus giving the FAA an opportunity to again have a significant role in fixed wing operations. Just a thought, please don’t be too rude to me!
HMMMMMMMMMMMMMMMMMMMMM!
Whatever, but I can only magine that the F35B will be good for just one thing and that is as a very expensive Close Support Aircraft.
FB
Whatever, but I can only magine that the F35B will be good for just one thing and that is as a very expensive Close Support Aircraft.
FB
The STOVL vs CTOL (what is now called CATOBAR) preferences will include some or all of the following.
1. As noted above, STOVL lets the RAF retain cockpits while primarily living ashore, based on the idea that a two-week embarkation counts as delivering carrier strike capability. It's not evil, it's just the way the RAF percieves Maritime aviation.
2. There are those who suggest that launch/recovery rates will be quicker for STOVL. Launch rate almost certainly will be, but with larger CAGs (which is what QEC and it's CAG were designed to deliver) the recovery serial is more likely to resemble a CTOL recovery. More cabs in the pattern will lead to situations where delays build up.
3. Stand by for the myth about tankers to be trotted out. It is absolutely true that the Harrier did not need an organic tanker - although part of that is that there was no way of delivering one and that any fuel would only have to be jettisoned again to get you to VL recovery limits. The STOVL supporters have always assumed that they won't need Texaco, because they are less susceptible to a foul deck (there's always a spot to drop on). That isn't the case with F35B, where if you're doing a Rolling Vertical Landing, you'll need just as much deck area (or more) than an arrested recovery. Combine that with a larger number of cabs in the pattern and you'll need some form of fuel margin or tanker and with a combat radius about 60% of that of the F35C, that's really hitting your effectiveness.
Much of all this is literally down to people (RN, RAF, MoD CS & industry) confusing CVS/SHAR/GR7 ops with those of F35B and QEC. We're not buying a CVS/SHAR/GR7 replacement, we're buying (as justified by reams of operational analysis and campaign modelling) something else entirely.
The something else will also allow the UK to work with FR to provide a proper carrier capability in the Western hemisphere, which is another reason why the US are being so co-operative, as it allows then to reduce optempo and concentrate on 5th and 7th fleets.
1. As noted above, STOVL lets the RAF retain cockpits while primarily living ashore, based on the idea that a two-week embarkation counts as delivering carrier strike capability. It's not evil, it's just the way the RAF percieves Maritime aviation.
2. There are those who suggest that launch/recovery rates will be quicker for STOVL. Launch rate almost certainly will be, but with larger CAGs (which is what QEC and it's CAG were designed to deliver) the recovery serial is more likely to resemble a CTOL recovery. More cabs in the pattern will lead to situations where delays build up.
3. Stand by for the myth about tankers to be trotted out. It is absolutely true that the Harrier did not need an organic tanker - although part of that is that there was no way of delivering one and that any fuel would only have to be jettisoned again to get you to VL recovery limits. The STOVL supporters have always assumed that they won't need Texaco, because they are less susceptible to a foul deck (there's always a spot to drop on). That isn't the case with F35B, where if you're doing a Rolling Vertical Landing, you'll need just as much deck area (or more) than an arrested recovery. Combine that with a larger number of cabs in the pattern and you'll need some form of fuel margin or tanker and with a combat radius about 60% of that of the F35C, that's really hitting your effectiveness.
Much of all this is literally down to people (RN, RAF, MoD CS & industry) confusing CVS/SHAR/GR7 ops with those of F35B and QEC. We're not buying a CVS/SHAR/GR7 replacement, we're buying (as justified by reams of operational analysis and campaign modelling) something else entirely.
The something else will also allow the UK to work with FR to provide a proper carrier capability in the Western hemisphere, which is another reason why the US are being so co-operative, as it allows then to reduce optempo and concentrate on 5th and 7th fleets.
Last edited by Not_a_boffin; 26th Mar 2012 at 10:22.
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I am not surprised at the comments re power supplies. The situation is somewhat more complex than might be imagined.
1/ There must be a stable supply of power
2/ The power loading throughout the ship must be load balanced (this will require a probable extensive redesign)
3/ The system must be able to accept shock load/ unload situations due to the way that the EMALS cycles builds up power for firing off aircraft
4/ There will be feedback to other circuits. There nearly always is
5/ Electromagnetic interference.
John,
Apologies for not responding sooner. I do have an understanding of turbines. Your response was much appreciated.
1/ There must be a stable supply of power
2/ The power loading throughout the ship must be load balanced (this will require a probable extensive redesign)
3/ The system must be able to accept shock load/ unload situations due to the way that the EMALS cycles builds up power for firing off aircraft
4/ There will be feedback to other circuits. There nearly always is
5/ Electromagnetic interference.
John,
Apologies for not responding sooner. I do have an understanding of turbines. Your response was much appreciated.
Last edited by hval; 26th Mar 2012 at 17:02. Reason: Electromagnetic interference
Hval
I suspect that most of the load balancing / shock effects will actually be contained "downstream" of the Prime Power Interface. I'm not a sparky and don't wear pink ovies, but I believe that the "shock" elements you refer to will be no different to those on a CVN and should therefore be catered for within the existing EMALS design.
Where there will be a difference will be re-jigging the ships IPMS software to recognise and accommodate the load demanded by the PPI to energise the flywheel. However, that load demanded should build up relatively smoothly to a defined level, before decaying as the storage device (flywheel) reaches full capacity, again, downstream of the PPI. In my simple mind, all that requires is that the ships distribution grid (IPMS) software recognises the load characteristics of that particular consumer and does not trip. All the energy feedbck/harmonics and clever bits should be isolated on the EMALS side of the PPI.
I'm sure there will be more complexities to it than that - I don't for one minute underestimate the demands of this type of engineering, that's why it's called electrickery. However, I would be very surprised if any "redesign" required extensive hardware changes, particularly when the EMALS / AAG system should have been designed from the off to be standalone systems acting merely as loads on the grid.
Your point on EMI however, is well made, although again, I should have thought that the location of the EMALS system ought to minimise the effect on the ships systems.
I suspect that most of the load balancing / shock effects will actually be contained "downstream" of the Prime Power Interface. I'm not a sparky and don't wear pink ovies, but I believe that the "shock" elements you refer to will be no different to those on a CVN and should therefore be catered for within the existing EMALS design.
Where there will be a difference will be re-jigging the ships IPMS software to recognise and accommodate the load demanded by the PPI to energise the flywheel. However, that load demanded should build up relatively smoothly to a defined level, before decaying as the storage device (flywheel) reaches full capacity, again, downstream of the PPI. In my simple mind, all that requires is that the ships distribution grid (IPMS) software recognises the load characteristics of that particular consumer and does not trip. All the energy feedbck/harmonics and clever bits should be isolated on the EMALS side of the PPI.
I'm sure there will be more complexities to it than that - I don't for one minute underestimate the demands of this type of engineering, that's why it's called electrickery. However, I would be very surprised if any "redesign" required extensive hardware changes, particularly when the EMALS / AAG system should have been designed from the off to be standalone systems acting merely as loads on the grid.
Your point on EMI however, is well made, although again, I should have thought that the location of the EMALS system ought to minimise the effect on the ships systems.
Last edited by Not_a_boffin; 26th Mar 2012 at 18:47.
Originally Posted by kbrokman
Apart from the apparent advantages of going with VTOL
-Useable on land without a proper runway at hand, close to the frontline.
-no arrestor wire and cat necessary
-looks megacool.
-Useable on land without a proper runway at hand, close to the frontline.
-no arrestor wire and cat necessary
-looks megacool.
Close to the frontline: Remind me how expensive these jets are?
No arrestor wire and cat necessary: Which normally means reduced payload, fuel, etc.
Looks megacool: Where do I start? It's supposed to be a fast jet, not a helicopter - helicopters hovering and landing look cool, jets doing it do not. Going really fast looks cool, sitting ove and airfield at a display and bowing to the nearby sewage farm does not. Watching a25 tons of hurtling metal and thrust being caught by a trap and stopping on a carrier deck looks megacool - flopping onto the same deck in an undignified manner does not.
Partly in jest, partly...
No arrestor wire and cat necessary: Which normally means reduced payload, fuel, etc.
Looks megacool: Where do I start? It's supposed to be a fast jet, not a helicopter - helicopters hovering and landing look cool, jets doing it do not. Going really fast looks cool, sitting ove and airfield at a display and bowing to the nearby sewage farm does not. Watching a25 tons of hurtling metal and thrust being caught by a trap and stopping on a carrier deck looks megacool - flopping onto the same deck in an undignified manner does not.
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The only military people I can conceive of preferring the -B model are senior ex-Harrier pilots who might be struggling to let go of their unique selling point.
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Not_a_boffin,
You are correct that most of the load balancing is carried out downstream, but there is still some major load/ unload being carried out. You would need to increase the number of alternators to smooth out this. This doesn't prevent a problem when the system is turned on or off, or when energy is drawn for the alternators. Then there are the changes in energy load that take place through using motors, air conditioning, weapon systems, lifts, hoists, lighting, safety systems, galleys and everything else. Generators do not take kindly to heavy load variations. Then there has to be capability in case a generator fails (normally three generators on a ship, one for spare). In this case we have two Trent turbines and four diesel generators to provide propulsion power and energy to all other systems.
Most of the redesign work can take place around the main busbar and distribution panels. Still need to make a bunch of holes through bullheads and decks to run the additional shielded cables to a shielded room. Having said that, there may be space in the upgrade allowance, and a nice tidy path/s as well.
You are correct that most of the load balancing is carried out downstream, but there is still some major load/ unload being carried out. You would need to increase the number of alternators to smooth out this. This doesn't prevent a problem when the system is turned on or off, or when energy is drawn for the alternators. Then there are the changes in energy load that take place through using motors, air conditioning, weapon systems, lifts, hoists, lighting, safety systems, galleys and everything else. Generators do not take kindly to heavy load variations. Then there has to be capability in case a generator fails (normally three generators on a ship, one for spare). In this case we have two Trent turbines and four diesel generators to provide propulsion power and energy to all other systems.
Most of the redesign work can take place around the main busbar and distribution panels. Still need to make a bunch of holes through bullheads and decks to run the additional shielded cables to a shielded room. Having said that, there may be space in the upgrade allowance, and a nice tidy path/s as well.
Last edited by hval; 26th Mar 2012 at 19:16. Reason: Forgot to add..
Hval
Thanks for the response. However, I suspect that the load variation on the generators will only be about 4-5% in this case. If you have a propulsive load of between 60 to 80 MW for flight ops, with the likely load on each PPI of the order of 1-2 MW, then that's about the right figure.
The variations for pump motor starters, weps lifts etc are likely to be of the order of another 5MW tops shipwide. I suspect what might be more difficult to control is the current variation.
Don't forget that the system distributes at 11kV, stepped down to 440 locally, so it's likely to be a local load on the relevant EDC, rather than direct on the generating plant.
Not by any means my specialty, but this ship is unlike most others in the fleet in that she's a true power station concept, rather than a propulsion system, plus generators.
Thanks for the response. However, I suspect that the load variation on the generators will only be about 4-5% in this case. If you have a propulsive load of between 60 to 80 MW for flight ops, with the likely load on each PPI of the order of 1-2 MW, then that's about the right figure.
The variations for pump motor starters, weps lifts etc are likely to be of the order of another 5MW tops shipwide. I suspect what might be more difficult to control is the current variation.
Don't forget that the system distributes at 11kV, stepped down to 440 locally, so it's likely to be a local load on the relevant EDC, rather than direct on the generating plant.
Not by any means my specialty, but this ship is unlike most others in the fleet in that she's a true power station concept, rather than a propulsion system, plus generators.