F-35 Cancelled, then what ?
As with the V22, Killface, the F-35 is both expensive and in certain ways on the bleeding edge of tech, or at least the combination of various sorts of tech. When things are that expensive, they get more scrutiny than less pricey systems. Someone wants that funding to go to their pet project ...
It's politics, not aerodynamics.
It's politics, not aerodynamics.
Join Date: Jul 2008
Location: Australia OZ
Age: 75
Posts: 2,582
Likes: 0
Received 52 Likes
on
45 Posts
STOVL DOORs IAS Limits
On previous page of this thread 'CoffmanStarter' asked: "...I'm not FJ conversant/experienced ... so just a question of curiosity ...
What is the transition speed tolerance (from Engineborne vertical to Wingborne horizontal flight) for that damn great intake flap before it becomes a huge speed retarding spoiler ... does the intake flap have selective open/close settings or is it either fully open or fully closed ?..."
Some public statistics....
F-35 Begins Year With Test Objectives Unmet [STOVL IAS Change] Jan 4, 2011 By Graham Warwick
http://www.aviationweek.com/aw/gener...p22-279507.xml
"...operation of the lift-fan door rescheduled to reduce airloads on the auxiliary doors during semi-jet-borne flight.
The lift-fan door was programmed to open to 65 deg. below 120 kt., and to 35 deg. above that airspeed. But with the large door fully open, loads on the auxiliary-inlet doors behind it are reduced, so the schedule has been changed to keep the lift-fan door open 65 deg. up to 165 kt. during a short takeoff, he [McFarlan] says...."
_____________________________
JSF programme to proceed with UK-specific land-based carrier trials Gareth Jennings 09 Jul 2012
JSF programme to proceed with UK-specific land-based carrier trials - Farnborough 2012 | IHS Jane's
"...Wilson noted that the lift-fan door behind the cockpit does not affect the aircraft's handling when open for the landing and take-off phases of flight. "There are no issues in terms of drag," he said. "We can open [the door] up to speeds of 250 kt and you don't feel a thing in the cockpit."..."
What is the transition speed tolerance (from Engineborne vertical to Wingborne horizontal flight) for that damn great intake flap before it becomes a huge speed retarding spoiler ... does the intake flap have selective open/close settings or is it either fully open or fully closed ?..."
Some public statistics....
F-35 Begins Year With Test Objectives Unmet [STOVL IAS Change] Jan 4, 2011 By Graham Warwick
http://www.aviationweek.com/aw/gener...p22-279507.xml
"...operation of the lift-fan door rescheduled to reduce airloads on the auxiliary doors during semi-jet-borne flight.
The lift-fan door was programmed to open to 65 deg. below 120 kt., and to 35 deg. above that airspeed. But with the large door fully open, loads on the auxiliary-inlet doors behind it are reduced, so the schedule has been changed to keep the lift-fan door open 65 deg. up to 165 kt. during a short takeoff, he [McFarlan] says...."
_____________________________
JSF programme to proceed with UK-specific land-based carrier trials Gareth Jennings 09 Jul 2012
JSF programme to proceed with UK-specific land-based carrier trials - Farnborough 2012 | IHS Jane's
"...Wilson noted that the lift-fan door behind the cockpit does not affect the aircraft's handling when open for the landing and take-off phases of flight. "There are no issues in terms of drag," he said. "We can open [the door] up to speeds of 250 kt and you don't feel a thing in the cockpit."..."
Last edited by SpazSinbad; 21st May 2013 at 22:44. Reason: format
out of the runway and the Fuzzy-Wuzzies were swarming the fence?
Join Date: Jul 2008
Location: Australia OZ
Age: 75
Posts: 2,582
Likes: 0
Received 52 Likes
on
45 Posts
'Typhoid' crashes on only short runway attempting to carry out an unauthorised short landing, pilot ejects safely to face court martial later. F-35Bs unable to STO VTO to a disease free zone to 'weight up' for usual STOVL ops ashore. Substitute a Helo Crash on Deck for the 'typhoid' ashore for the VTO F-35B to translate to nearby suitable flat deck to carry on. To cheer ye all up here is a new version of the CVF animation video (wot no STOVL takeoff?):Queen Elizabeth Class Aircraft Carriers in Operation
"Published on May 21, 2013
A glimpse of what the finished ships will look like when fully operational"
Join Date: Feb 2009
Location: Waiting to return to the Loire.
Age: 54
Posts: 386
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for the YouTube Spaz.
Nice to see the Chinooks on it. If the CGI modelling is accurate (no reason to doubt it) the hangar space looks huge when they are bringing the mighty Wokka out onto the lift. A pity that they didn't digitalise the CHF onto it as well.
Nice to see the Chinooks on it. If the CGI modelling is accurate (no reason to doubt it) the hangar space looks huge when they are bringing the mighty Wokka out onto the lift. A pity that they didn't digitalise the CHF onto it as well.
Join Date: Oct 2004
Location: Great Britain
Posts: 471
Likes: 0
Received 0 Likes
on
0 Posts
A pity they didn't digitise CHF as well.
Bismark
Fixed it for you, no charge!
The 100 year experiment will have been completed 4 years previously, been proven to be a huge success, and all the FAA and AAC FW and RW assets will have been redistributed to the RAF
Do a Hover - it avoids G
Join Date: Oct 1999
Location: Chichester West Sussex UK
Age: 91
Posts: 2,206
Likes: 0
Received 0 Likes
on
0 Posts
LowObservable
VTOs worked well from Atlantic Conveyor.
A ferry sortie from a VTO offers real operational flexibility.
But you know all that.
JF
VTOs worked well from Atlantic Conveyor.
A ferry sortie from a VTO offers real operational flexibility.
But you know all that.
JF
True enough, John. And as you say that, I recall that recently the Navy has been talking about F-35s from their Mobile Landing Platform, a logistics ship.
If you wanted to put an F-35-heavy wing on an MEU at sea, this would be one way of doing it.
What's odd is that I have never seen VTO mentioned once until now.
If you wanted to put an F-35-heavy wing on an MEU at sea, this would be one way of doing it.
What's odd is that I have never seen VTO mentioned once until now.
Join Date: Dec 2006
Location: UK
Posts: 799
Likes: 0
Received 0 Likes
on
0 Posts
LO,
Perhaps I can help. VTO has been a requirement for F-35 since Day One.
However, as the guys writing the requirements were technically informed, they didn't try to make the aircraft do a VTO with an operational load, as they knew that this was beyond the laws of physics as they stood in 2000. However, they did want the ability to use VTO to reposition an F-35 from one deck to another. The 'Atlantic Conveyor' was a very pertinent example - and the US War Colleges have been using the Falklands War as a textbook example of tactical flexibility these past 30 odd years.
Re the speed limits for transitions - thanks to SpazSinbad for a really useful post. Thanks, wings.
Hope this helps
Engines
Perhaps I can help. VTO has been a requirement for F-35 since Day One.
However, as the guys writing the requirements were technically informed, they didn't try to make the aircraft do a VTO with an operational load, as they knew that this was beyond the laws of physics as they stood in 2000. However, they did want the ability to use VTO to reposition an F-35 from one deck to another. The 'Atlantic Conveyor' was a very pertinent example - and the US War Colleges have been using the Falklands War as a textbook example of tactical flexibility these past 30 odd years.
Re the speed limits for transitions - thanks to SpazSinbad for a really useful post. Thanks, wings.
Hope this helps
Engines
Join Date: Dec 2006
Location: UK
Posts: 799
Likes: 0
Received 0 Likes
on
0 Posts
Glad,
There were a very specific set of requirements set out in the Joint Operational Requirements Document (JORD), with a small number identified as KPPs. Yes, that adds up to a 'lot'. The F-35 programme is doing its level best to meet them all.
Did you have any specific ones in mind? Happy to help explain where they are against them, as far as I can.
Best regards
Engines
There were a very specific set of requirements set out in the Joint Operational Requirements Document (JORD), with a small number identified as KPPs. Yes, that adds up to a 'lot'. The F-35 programme is doing its level best to meet them all.
Did you have any specific ones in mind? Happy to help explain where they are against them, as far as I can.
Best regards
Engines
Join Date: Jul 2008
Location: Australia OZ
Age: 75
Posts: 2,582
Likes: 0
Received 52 Likes
on
45 Posts
F-35B Door Limits Pt.2
For 'Engines' some more F-35B 'Doors of Perception' trivia....
F-35B - Doors (Pt. 2) by Graham Warwick Dec/9/2011
Blogs
“Dorsal auxiliary air-inlet doors, which open in STOVL mode to increase mass flow into the engine & generate an add-itional 7,000lb of vertical thrust, were found to flutter in semi-jetborne flight, causing premature hinge wear. The initial fix was to modify operation of the large lift-fan door forward of the auxiliary inlet to stay fully open to higher airspeed on short take-offs to ‘shelter’ the clamshell doors. Instead of closing to the 35° mid position at 125kt the aft-hinged lift-fan door now stays fully open at 65° to 170kt on take-off, & begins to open to 65° at 160kt on approach to landing.”
_________________
F-35 Flight Testing At Pax [excerpt] By Eric Hehs 15 October 2012
Code One Magazine: F-35 Flight Testing At Pax
"...The test team at Pax is also exploring the maximum speed end of the STOVL portion of the flight envelope, which is 250 knots. “The buffet and noise is significant when we have the upper lift fan door all the way open, which is an angle of sixty-five degrees, at that speed [250 knots],” Faidley said....
...Some of the flight test aircraft have special software that allows the pilot to override the standard control laws that actuate the various doors and nozzle angles. The flight control laws for the STOVL variant have six modes that are associated with specific actuations. Mode 1 defines conventional flight. Mode 4 defines STOVL. The other four modes define transitional states between the two primary modes. “If a pilot loses a hydraulic system in Mode 2, we know that the doors associated with STOVL flight will be positioned a certain way,” Faidley explained. “We are seeing how well the airplane flies in those conditions.”...”
F-35B - Doors (Pt. 2) by Graham Warwick Dec/9/2011
Blogs
“Dorsal auxiliary air-inlet doors, which open in STOVL mode to increase mass flow into the engine & generate an add-itional 7,000lb of vertical thrust, were found to flutter in semi-jetborne flight, causing premature hinge wear. The initial fix was to modify operation of the large lift-fan door forward of the auxiliary inlet to stay fully open to higher airspeed on short take-offs to ‘shelter’ the clamshell doors. Instead of closing to the 35° mid position at 125kt the aft-hinged lift-fan door now stays fully open at 65° to 170kt on take-off, & begins to open to 65° at 160kt on approach to landing.”
_________________
F-35 Flight Testing At Pax [excerpt] By Eric Hehs 15 October 2012
Code One Magazine: F-35 Flight Testing At Pax
"...The test team at Pax is also exploring the maximum speed end of the STOVL portion of the flight envelope, which is 250 knots. “The buffet and noise is significant when we have the upper lift fan door all the way open, which is an angle of sixty-five degrees, at that speed [250 knots],” Faidley said....
...Some of the flight test aircraft have special software that allows the pilot to override the standard control laws that actuate the various doors and nozzle angles. The flight control laws for the STOVL variant have six modes that are associated with specific actuations. Mode 1 defines conventional flight. Mode 4 defines STOVL. The other four modes define transitional states between the two primary modes. “If a pilot loses a hydraulic system in Mode 2, we know that the doors associated with STOVL flight will be positioned a certain way,” Faidley explained. “We are seeing how well the airplane flies in those conditions.”...”
Last edited by SpazSinbad; 26th May 2013 at 13:41. Reason: Title Oops - 45 changed to 35
Join Date: Jul 2008
Location: Australia OZ
Age: 75
Posts: 2,582
Likes: 0
Received 52 Likes
on
45 Posts
F-35B Vertical Take Off Requirement Quotes
A selection of Vertical Takeoff Requirements quotes for the F-35B with a funny one at the start for our amusement.... 
An Update on the F-35 Integrated Training Center At Eglin AFB By Robbin Laird 09 Sep 2012
An Update on the F-35 Integrated Training Center At Eglin AFB | SLDInfo
Col. Tomassetti: "...We have lots of visitors here at Eglin and we get a chance to put many of them in the simulators. And one of the things that we do with everybody is we let them do a vertical takeoff, fly around and come back and do a vertical landing, either at the field or at the ship...."
VIMEO Video Interview: Col. Tomassetti on the Progress in F-35 Training on Vimeo
___________________
EAF enables JSF landing anywhere, everywhere 29-Jun-09
NAVAIR - U.S. Navy Naval Air Systems Command - Navy and Marine Corps Aviation Research, Development, Acquisition, Test and Evaluation
"...Although the AM-2 matting is serving its purpose as vertical take-off and landing (VTOL) pads and a 1,900 x 96-foot runway for the EAF/STOVL testing, it also doubles as the run-up for a test “ski-jump” used in conjunction with JSF testing for the British Royal Navy. The AM-2 matting and the 12-degree ski-jump ramp were installed at the centerfield area last month...."
____________________
F-35B STOVL Testing Moving Ahead Rapidly Shane McGlaun (Blog) - May 17, 2011
DailyTech - F-35B STOVL Testing Moving Ahead Rapidly
"..."The testing has been going very well over the last couple of months," said Marine Lt. Col. Matthew Kelly, an F-35 test pilot with an F/A-18 Hornet background. "We have performed all the vertical landings necessary to go out to the boat and do testing. We're at about 80 percent of the short takeoffs."
Pilots at Naval Air Station Patuxent River, Md have flown about 125 sorties with many of those dedicated to getting the aircraft ready for shipboard tests. Kelly notes that they are in good position to begin those ship tests this fall. The F-35B will also eventually be required to perform vertical takeoffs, but for now, the STOVL trials have been deemed more important...."
_________________________
Construction for JSF marks another milestone Dec 24, 2011 by CPL. AARON DIAMANT
Construction for JSF marks another milestone, construction, jsf, pad - News - YumaSun
"Construction in anticipation of the Joint Strike Fighter's arrival in Yuma reached another first Dec. 8, as the first section of special, high-temperature concrete was poured at vertical takeoff and landing pad four on Marine Corps Air Station Yuma flightline. “This is a special, high-temperature concrete designed to handle the heat from the JSF,” said Marie Torres, president of MRM Construction Services, the company completing the project. “We've poured several test sections before, but this is the first time this particular mix has been used.”
The pad, which will be used for vertical takeoffs and landings, was designed to have a long service life, & is the first to be designed & con-structed specifically for the JSF..."
An Update on the F-35 Integrated Training Center At Eglin AFB By Robbin Laird 09 Sep 2012
An Update on the F-35 Integrated Training Center At Eglin AFB | SLDInfo
Col. Tomassetti: "...We have lots of visitors here at Eglin and we get a chance to put many of them in the simulators. And one of the things that we do with everybody is we let them do a vertical takeoff, fly around and come back and do a vertical landing, either at the field or at the ship...."
VIMEO Video Interview: Col. Tomassetti on the Progress in F-35 Training on Vimeo
___________________
EAF enables JSF landing anywhere, everywhere 29-Jun-09
NAVAIR - U.S. Navy Naval Air Systems Command - Navy and Marine Corps Aviation Research, Development, Acquisition, Test and Evaluation
"...Although the AM-2 matting is serving its purpose as vertical take-off and landing (VTOL) pads and a 1,900 x 96-foot runway for the EAF/STOVL testing, it also doubles as the run-up for a test “ski-jump” used in conjunction with JSF testing for the British Royal Navy. The AM-2 matting and the 12-degree ski-jump ramp were installed at the centerfield area last month...."
____________________
F-35B STOVL Testing Moving Ahead Rapidly Shane McGlaun (Blog) - May 17, 2011
DailyTech - F-35B STOVL Testing Moving Ahead Rapidly
"..."The testing has been going very well over the last couple of months," said Marine Lt. Col. Matthew Kelly, an F-35 test pilot with an F/A-18 Hornet background. "We have performed all the vertical landings necessary to go out to the boat and do testing. We're at about 80 percent of the short takeoffs."
Pilots at Naval Air Station Patuxent River, Md have flown about 125 sorties with many of those dedicated to getting the aircraft ready for shipboard tests. Kelly notes that they are in good position to begin those ship tests this fall. The F-35B will also eventually be required to perform vertical takeoffs, but for now, the STOVL trials have been deemed more important...."
_________________________
Construction for JSF marks another milestone Dec 24, 2011 by CPL. AARON DIAMANT
Construction for JSF marks another milestone, construction, jsf, pad - News - YumaSun
"Construction in anticipation of the Joint Strike Fighter's arrival in Yuma reached another first Dec. 8, as the first section of special, high-temperature concrete was poured at vertical takeoff and landing pad four on Marine Corps Air Station Yuma flightline. “This is a special, high-temperature concrete designed to handle the heat from the JSF,” said Marie Torres, president of MRM Construction Services, the company completing the project. “We've poured several test sections before, but this is the first time this particular mix has been used.”
The pad, which will be used for vertical takeoffs and landings, was designed to have a long service life, & is the first to be designed & con-structed specifically for the JSF..."
Last edited by SpazSinbad; 23rd May 2013 at 08:13. Reason: bold
Join Date: Apr 2009
Location: Sydney
Age: 45
Posts: 243
Likes: 0
Received 0 Likes
on
0 Posts
I'm surprised they didn't test the vertical take off when testing vertical landings. Barring any technical reasons for delaying the test appears to be just about a non event.
Join Date: Jul 2008
Location: Australia OZ
Age: 75
Posts: 2,582
Likes: 0
Received 52 Likes
on
45 Posts
F-35B Vertical Take Off Testing NOT a Priority
'dat581' you should set the program priorities to suit your proclivities for sure - otherwise this is the reason (as seen in above quote):
"...The F-35B will also eventually be required to perform vertical takeoffs, but for now, the STOVL trials have been deemed more important..."
__________________
ADDITIONAL QUOTE re VTO testing requirement:
F-35 Tests Proceed, Revealing F/A-18-Like Performance 16 May 2011 By DAVE MAJUMDAR
F-35 Tests Proceed, Revealing F/A-18-Like Performance | Defense News | defensenews.com
"...Eventually, the F-35B will perform vertical takeoffs, but that testing has yet to be performed because other STOVL trials are of more immediate import, Kelly [Marine Lt. Col. Matthew Kelly, an F-35 test pilot with an F/A-18 Hornet background] said.
"There is a requirement for that and we do plan on performing vertical takeoffs," he said...."
"...The F-35B will also eventually be required to perform vertical takeoffs, but for now, the STOVL trials have been deemed more important..."
__________________
ADDITIONAL QUOTE re VTO testing requirement:
F-35 Tests Proceed, Revealing F/A-18-Like Performance 16 May 2011 By DAVE MAJUMDAR
F-35 Tests Proceed, Revealing F/A-18-Like Performance | Defense News | defensenews.com
"...Eventually, the F-35B will perform vertical takeoffs, but that testing has yet to be performed because other STOVL trials are of more immediate import, Kelly [Marine Lt. Col. Matthew Kelly, an F-35 test pilot with an F/A-18 Hornet background] said.
"There is a requirement for that and we do plan on performing vertical takeoffs," he said...."
Last edited by SpazSinbad; 24th May 2013 at 10:12. Reason: Add New Quote
Join Date: Dec 2006
Location: UK
Posts: 799
Likes: 0
Received 0 Likes
on
0 Posts
Spaz,
Many thanks - very useful. The items you've posted are really useful, in that they illustrate the complexity of getting a powered lift vehicle to work properly through all points of the transition from hover to forward flight (and back again).
dat581 - The VTO is a great illustration of the fact that 'just because it looks like a non-event, it's really not'. Coming down to the ground from hover height will cause the airflows of hot and cold gas under and around the aircraft to set themselves up in a certain way, especially the cold air 'screen' between the hot exhaust and the air intakes. Staring with the aircraft on the ground will generate a different pattern of gas flows, some of which you might not want. These flows will also be affected by relative wind.
As ever with powered lift aircraft, you start with clever and thorough design, and then go into careful and thorough testing.
Hope this helps,
Engines
Many thanks - very useful. The items you've posted are really useful, in that they illustrate the complexity of getting a powered lift vehicle to work properly through all points of the transition from hover to forward flight (and back again).
dat581 - The VTO is a great illustration of the fact that 'just because it looks like a non-event, it's really not'. Coming down to the ground from hover height will cause the airflows of hot and cold gas under and around the aircraft to set themselves up in a certain way, especially the cold air 'screen' between the hot exhaust and the air intakes. Staring with the aircraft on the ground will generate a different pattern of gas flows, some of which you might not want. These flows will also be affected by relative wind.
As ever with powered lift aircraft, you start with clever and thorough design, and then go into careful and thorough testing.
Hope this helps,
Engines
Ecce Homo! Loquitur...
F/A-18F CFT & Weapons Pod mockup in St Louis
While it has been known for sometime that Boeing and the US Navy intend to fly a modified F/A-18F Super Hornet equipped with conformal fuel tanks (CFTs) and a weapons pod later this summer, some new details are emerging.
When the modified Rhino--as the Super Hornet is affectionately known--does fly in late August or early September over the Navy's Atlantic range with the new hardware, those CFTs and weapons pod will not be functional, says Mike Gibbons, Boeing's F/A-18 program manager. The idea is to test the aerodynamic qualities of those representative shapes, he says. Mark Gammon, Boeing's Hornet advanced projects chief, also notes that the aircraft will have a mock-up of an internally-mounted infrared search and track system mounted along with a slew of radar cross-section enhancement measures.
Gammon, who has worked on the Hornet since the first days of the original F/A-18A classic model jets, says that the CFTs won't add any cruise drag at high subsonic speeds, but it will have a negative impact on drag at transonic speeds--but the company has done a lot of engineering work to try mitigate that. In fact, Gammon notes, at low airspeeds, sometimes overall drag with the CFTs is actually lower than a clean aircraft's.
Configured with the CFTs and weapons pod carrying four AMRAAMs, the jet performs roughly the same as a Super Hornet carrying four external AIM-120s.
Anyways, Boeing showed off this brand new real F/A-18F equipped with mockup CFTs, weapons pods and other hardware.
While it has been known for sometime that Boeing and the US Navy intend to fly a modified F/A-18F Super Hornet equipped with conformal fuel tanks (CFTs) and a weapons pod later this summer, some new details are emerging.
When the modified Rhino--as the Super Hornet is affectionately known--does fly in late August or early September over the Navy's Atlantic range with the new hardware, those CFTs and weapons pod will not be functional, says Mike Gibbons, Boeing's F/A-18 program manager. The idea is to test the aerodynamic qualities of those representative shapes, he says. Mark Gammon, Boeing's Hornet advanced projects chief, also notes that the aircraft will have a mock-up of an internally-mounted infrared search and track system mounted along with a slew of radar cross-section enhancement measures.
Gammon, who has worked on the Hornet since the first days of the original F/A-18A classic model jets, says that the CFTs won't add any cruise drag at high subsonic speeds, but it will have a negative impact on drag at transonic speeds--but the company has done a lot of engineering work to try mitigate that. In fact, Gammon notes, at low airspeeds, sometimes overall drag with the CFTs is actually lower than a clean aircraft's.
Configured with the CFTs and weapons pod carrying four AMRAAMs, the jet performs roughly the same as a Super Hornet carrying four external AIM-120s.
Anyways, Boeing showed off this brand new real F/A-18F equipped with mockup CFTs, weapons pods and other hardware.
