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No cats and flaps ...... back to F35B?

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No cats and flaps ...... back to F35B?

Old 31st May 2012, 19:44
  #981 (permalink)  
 
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From afar, it looks as if the sequester is likely to be avoided once the presidential election is out of the way...However, our US contributors are closer to the politics than I am so maybe they can comment with more authority
I've been in the US for the last 6 months and the political climate aint too hot, the election isn't until November, and the president elect doesn't actually become the president until a week or so later. Plus, the two parties are pretty damn polarised, at the moment; my bet is that they return to a democrat president with a republican congress. Most democrats know that more defence cuts would still leave the US far more powerful than anyone else, and social security takes priority for them. I guess we'll have to watch and see!
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Old 31st May 2012, 20:03
  #982 (permalink)  
 
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I've been in the US for the last 6 months and the political climate aint too hot, the election isn't until November, and the president elect doesn't actually become the president until a week or so later.
Just to set things straigth, the US presidential elections are between 2 and 8 november , on a tuesday aka election day.
Contrary to many other countries, the new US president (or re-elected President) is only inaugurated in the beginning of the following year on january the 20th, an almost 3 month difference.
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Old 31st May 2012, 22:14
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kbrockman,

well there we go, get ready for sequestration
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Old 31st May 2012, 23:40
  #984 (permalink)  
 
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All kidding aside, it has been the policie of every outgoing
president to Enact as many new policies as possible, especially if you think that the incoming president would disapprove.
This practice has been used by presidents of both political parties with increasing fervor since Ronald Reagan.

Could be very interesting to see what happens if Obama has to give way for Romney, these last 3 months can be very interesting (also for the military), to say the least.

look up "Midnight regulations"

Last edited by kbrockman; 31st May 2012 at 23:46.
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Old 1st Jun 2012, 09:01
  #985 (permalink)  
 
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It'll be Obama and he'll cut the F-35

Romney can't even get his own side to vote for him
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Old 1st Jun 2012, 09:07
  #986 (permalink)  
 
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It'll be Obama and he'll cut the F-35

Romney can't even get his own side to vote for him
If , like you say, it'll be Obama that gets reelected, he won't be a lame duck president, therefor he won't be doing drastic things after election day.
Obama's reelection might well be a good thing for the F35 as things will be going further as if nothing has happened.
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Old 1st Jun 2012, 10:20
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BECAUSE he is not running for re-election again he can do what he likes - cancel the F-35 and buy a lot of F-18's (or even a few more F-22's) to keep the Military Industrial complex quiet and still have cash left over to cut the deficit
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Old 1st Jun 2012, 22:15
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Precisely... a few months ago he was overheard (via live mics that he thought were dead) telling Putin "give me a little space, this is an election year. After November I'll be able to settle your worries over the "European missile shield"".

He has said similar things to others who have complained their views are being shunted aside... various gun-ban groups among them.


He has made it clear that many of the policies he has followed were "re-elect the President policies"... and that once he doesn't have to worry about elections many policies will change.
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Old 2nd Jun 2012, 05:51
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Impressive video of the -B landing and taking off on the boat.


It seems to do very well in perfectly smooth seas, in daylight and a million miles visibility.



As long as the opposition promise to go no faster than Mach 1.6, not turn too tightly or carry too many weapons I think it will offer complete air averageness.


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Old 2nd Jun 2012, 08:27
  #990 (permalink)  
 
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Impressive video of the -B landing and taking off on the boat.
Indeed LOL
But as I have posted previously...as far as I can make out - the UK F35 is not planned to use the STO technique a la USMC,our plan seems to be to take off conventionally using the ski jump to lob it into the air but - unlike the harrier - after leaving the ski jump the pilot will not be able to select STO to gain lift etc.

So

(1) To me the landing gear looks a little flimsy (esp nose u/c leg) for ski jumping,if you look closely at the landings on the vid...you can see the noseleg flexing - by comparison the Harrier noseleg is built like a brick outhouse !

(2) So for takeoff all that ubercomplicated STOVL system is just dead weight/space...what a great idea LOL.

The harrier ski jumping technique was that as soon as you leave the ski jump then the pilot would select nozzles to 50ish degrees (preset on nozzle lever stop) and thereby gaining engine lift until not required.
I am sure John Farley would be able to give corrections/details
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Old 2nd Jun 2012, 09:07
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Longer Ron,

Perhaps I can help out a bit here.

The UK F-35B is required, and is perfectly able to, use a 'STO' technique to get airborne. The pilot will select 'powered lift' mode before it starts its take off run, and the aircraft will be partially jet borne and partially wing borne when it leaves the ramp. At the appropriate point as it flies away, the pilot selects back into 'conventional flight' mode.

The landing gear is fine. What you see on the video is the tyre flexing. The Harrier nose leg was massive because it was a 'bicycle' gear layout with the nose wheel taking around 50% of the weight of the aircraft. The F-35 has a conventional gear, with the front leg taking around 10% of the load. Oh, and I can testify that Harrier landing gears (outriggers and nose legs both) flexed plenty during deck ops. Stopped them breaking.

Hope this helps

Engines
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Old 2nd Jun 2012, 09:30
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Good morning Engines,
From what you are saying, will the 35 have a softer landing compared to those we sometimes witnessed when the harrier tended to shake the dust from the ship's fittings as they 'landed' on deck?
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Old 2nd Jun 2012, 10:29
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Glo,

Your question about landing speeds is a good one.

The last few feet as a jet powered lift aircraft nears a surface are both complex and critical. There is the ever present risk of Hot Gas Ingestion (HGI) as well as quite complex flow around and under the aircraft that can lead to 'suck down' and/or loss and deterioration of control.

The Harrier had some quite challenging characteristics in this area, although the fact that it was able to enter service without much artificial stability augmentation was a great achievement by the people who designed it. You probably know that a key to this was controlling the 'fountain' of air generated under the aircraft, hence the use of strakes, airbrake and on the AV-8B, a separate air dam.

The best way to avoid problems in this area for the Harrier was to land 'firmly', and so get through the critical 'near to ground' area as fast as practicable. Hence the sometimes firm landings. Although it's worth noting that the vertical velocity of these was still way less than is normally used in 'cat and trap' operations.

Fast forward to F-35B. The team have used design tools and test rigs that didn't exist in the 60s when the Harrier team did their work. That has given the F-35 team a much better understanding of how the jet operates close to the ground, and this has paid off. You'll see from the videos that they are using the inboard weapon bay doors as 'strakes' during vertical landings.

Another major difference from Harrier are the flight controls. F-35B has a 'rate command' system, which reduces pilot workload, but it did, in the early days, lead to some 'rebound' on landing - look up some of the X-35 videos that are out there. This appears to have been solved now.

Just a final offering - this area of the JSF design was one of the most critical and difficult, and has been led and largely executed by a hugely talented team of Brits. Cue for a BIG round of applause, I think.

Best regards as ever

Engines
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Old 2nd Jun 2012, 10:44
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Originally Posted by Engines
The last few feet as a jet powered lift aircraft nears a surface are both complex and critical. There is the ever present risk of Hot Gas Ingestion (HGI) as well as quite complex flow around and under the aircraft that can lead to 'suck down' and/or loss and deterioration of control.

The Harrier had some quite challenging characteristics in this area, although the fact that it was able to enter service without much artificial stability augmentation was a great achievement by the people who designed it. You probably know that a key to this was controlling the 'fountain' of air generated under the aircraft, hence the use of strakes, airbrake and on the AV-8B, a separate air dam.

The best way to avoid problems in this area for the Harrier was to land 'firmly', and so get through the critical 'near to ground' area as fast as practicable. Hence the sometimes firm landings. Although it's worth noting that the vertical velocity of these was still way less than is normally used in 'cat and trap' operations.

Fast forward to F-35B. The team have used design tools and test rigs that didn't exist in the 60s when the Harrier team did their work. That has given the F-35 team a much better understanding of how the jet operates close to the ground, and this has paid off. You'll see from the videos that they are using the inboard weapon bay doors as 'strakes' during vertical landings.

Another major difference from Harrier are the flight controls. F-35B has a 'rate command' system, which reduces pilot workload, but it did, in the early days, lead to some 'rebound' on landing - look up some of the X-35 videos that are out there. This appears to have been solved now.

Just a final offering - this area of the JSF design was one of the most critical and difficult, and has been led and largely executed by a hugely talented team of Brits. Cue for a BIG round of applause, I think
.

As ever a most informative and welcome contribution,
My accommodation on Centaur was directly underneath the area where aircraft touched down and thank goodness the deckhead (ceiling) lighting was always secured on shock absorbent mountings as I can confirm these landings were quite 'firm'.

The footage of the F-35B landing on the Wasp was very impressive for such a heavy aircraft and I look forward to watching the next round of sea trials. It makes sense using the one ship as there must be a learning curve and Wasp has lots of extra sensors fitted at numerous locations to record valuable information which no doubt will get applied through the fleet of ships that will eventually operate that type of aircraft..
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Old 2nd Jun 2012, 19:05
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Longer Ron,

Typical nozzle settings for ramp departures varied little but were normally 30-35 for the Harrier II; weight, WoD and 'spot' dependant of course! Also, a positive arrival from a vertical landing is what is required for the reasons Engines mentions however, on the ship it is even more critical as the ship moves. You need to get her down firmly and not hang up above the deck where sideways or, God forbid, rearwards drift may creep in. The gear was designed to take a hell of a thump down (>720 ft/sec) but lateral shear loads could result in 'Outrigger Mortis'. Stop her, steady her, smash her down with some grace.

As Engines nicely explains, F-35B will require a STOVL lift mode to get airborne from a ramped deck in most fits, unless lightweight, when a Kuznetsov departure could very well be possible but not advisable. I too applaud the British design team who have contributed so much to the B's lift system and control laws. A sterling effort indeed!
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Old 3rd Jun 2012, 08:07
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Thanks ICBM
I may have been thinking SH nozzle settings...or were they similar to the plastic pig ??

Thanks Engines
Some geezer on another forum had posted that the ski jump technique was going to be door closed and use reheat if necessary,but if that was the case you might as well use a STOBAR a/c LOL
I still think the nose gear looks a little flimsy for MTOW ski jumping
I know what you mean about tyre flexing but I looked at parts of that clip many times and I can see movement in the strut/fork area too!

rgds LR

Last edited by longer ron; 3rd Jun 2012 at 08:08.
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Old 3rd Jun 2012, 10:26
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I see this weeks "Flight" is calling for the USN to keep improving the F-18 and asks what use is a short range fighter if the carriers can't get close to China..........
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Old 3rd Jun 2012, 11:06
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Originally Posted by Heathrow Harry
and asks what use is a short range fighter if the carriers can't get close to China.........
Should we be asking what use is a short range fighter that has no air to air refuelling support or any decent AEW?

Will the carrier need to operate under the umbrella of shore based assets and if so why waste money on a very expensive warship?
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Old 3rd Jun 2012, 12:39
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Longer,

Don't know who the 'geezer' was, but sounds a bit less informed than others.

One of the many surprises in my engineering career was learning that bits of metal bend first, and then break. The fact that an undercarriage leg bends is not a problem, as long as it doesn't bend too much. The F-35 nose leg is a long travel telescopic design, mainly driven by weight considerations - it's the lightest possible design. However, it is definitely strong enough.

Trust me on this, loads are not the problem for ski jump, it's the load profile and whether the leg closes, as John Farley has already pointed out. One of the many insanely great features of the ski jump launch is that is a fairly gentle manoeuvre, both aerodynamically and structurally. It's the closest thing I have ever encountered to 'something for nothing'.

And it's another British invention - and a Royal Navy invention to boot. A nice thought for Jubilee Sunday.

Best Regards

Engines
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Old 3rd Jun 2012, 14:18
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it's the lightest possible design.
So is the Fin structure...and I understand that is a little on the weak side
I understand about flexible structures but 40 years as an aircraft technician has made me sceptical about some aspects of a/c design,all the a/c I have worked on have ended up being 'beefed up' in service,It is better to start off over engineered and perhaps gradually pare the weight down - to start off with 'just strong enough' is asking for trouble.
To return to the noseleg - surely it will get a little bit 'wobblier' during a rough sea/moving deck landing.
I worked on harriers for 11 years and well understand the reasoning behind the firm landing technique but I would not compare the weakness of a Sea Dog outrigger to a noseleg,the noseleg on the F35 looks more like the design you would find on a light a/c...a twin fork design would be both stronger and more stable.

rgds LR
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