VTOL: pros and cons

STOVL,..esp the VL bit has one major advantage...that britain hoped to use to the fullest if the cold war ever became hot..the harrier jets can be 'hidden' in forests with landing pads not much bigger than helicopters....good protection against enemy bombing raids..

The F-35 has a VTOL version
From what I've heard the F-35 VTOL version has some serious flaws in its design that was one of the major reasons the Pentagon wasn't very enthusiastic about the VTOL variant.
The Vtol F-35 most noticeable flaw was that the aircraft couldn't perform VTOL on any flat surfaces like the harrier because of the way its vertical lift fan and the suction ducts for the engine are placed. When the F-35 begins to land the aircraft suddenly looses thrust at a very critical moment just before it touches down causing it to fall suddenly, this cause damage to the gear and the loss of pilot control over the aircraft at a critical moment can even cause loss of human life, this is unacceptable especially for an aircraft used for military purposes. The main reason the plane looses thrust so suddenly is because the engine sucks in hot combusted air back into the engine and thus causes the engine power to fall suddenly. This problem prevents it from performing the VTOL maneuver on any given surface unlike the Harrier which can land vertically on any solid surface [ partly due to better design!] .
The guys at Lockheed have come up a landing pad for the F-35 which basically is a meshed pit to trap the hot gasses and preventing them from getting drawn into the engine again. This meshed " pit" is the Lockheed answer to the VTOL problem but I don't think that the DoD bought the idea of construction one of those on every airfield that the F-35 was likely to operate as the main advantage of a VTOL aircraft was that it could land on any solid surface thereby eliminating the need for a runway to establish air superiority. In the pics below you can just about make out the Landing Pad below the aircraft.




Another fear in the Vtol version of the F-35 is the design that the Lockheed guys have come up with for their Vtol engine, the drive shaft which drives the vertical Lift Fan [ which produces most of the down thrust] has a very small cross section to take such enormous amount of torque and speeds to drive the Lift Fan but Lockheed thinks that the driveshaft will be able to sustain the high loads. Also the Clutch which engages the driveshaft periodically also has a high risk of failure in operation due to design.
In the pic below the engine on top is the VTOL version and the one below is the VSTOL version. You can see the driveshaft and its narrow cross section which makes it look almost flimsy. Even if they get the material properties right they still have to consider the fluctuating loads and speeds the shaft will have to face.



Unlike the Harrier's Simple Pegasus engine the F-35 Vtol propulsion system is classically Lockheed [ i.e. damn expensive, damn costly to maintain & damn complicated !!]. With so many moving parts and doors the VTOL looks more like ballet than flight!

Very nice to look at but not when you want it to go to WAR !!
What would happen if during the course of the flight the driveshaft fails or the clutch jammes etc etc the point is greater the no of moving parts the higher the maintenance and likelihood of failure.

IAF>>

Originally posted by IAF101
The F-35 has a VTOL version
From what I've heard the F-35 VTOL version has some serious flaws in its design that was one of the major reasons the Pentagon wasn't very enthusiastic about the VTOL variant. ...

Good post, lots of research.

The image of the F-35B with the red vert stabilizer is an X-35B.
There actually is no F-35B VTOL.

Just as Intelgurl said, the F-35B has the ability under highly favorable if not perfect circumstances to perform a vertical take-off but that is not in the aircraft's "job description".

That is why Lockheed and all subcontractors on the program, the DOD's Joint Strike Fighter (JSF) Program, various news organizations, US congressmen (senate appropriations committee) and all international participants in the program recognize the F-35B as a "STOVL" aircraft.

Originally posted by Broadsword20068
Pilots are NOT a dying breed, as there are still too many complexities to unmanned aircraft that a pilot overcomes.....

There is a lot of high level speculation inside the USAF, DoD, the US military aerospace industry and various think tanks (the Cato Institute in particular) concerning whether combat pilots are indeed a dying breed or not.
Even at such high ranking and professional levels as just noted, there is little agreement on what the future holds for combat pilots.
So everyone on this thread commenting on the subject is certainly in good company and I therefore feel that there is no right or wrong answer, just conjecture.

To that end and being one who does work around UAV's and forward thinking professionals in the industry I will briefly share my thoughts.

Hunter Killer drones such as the Hellfire armed Predators already deployed will see more and more service... these units fly relatively low and can double as both an aerial ISR assest and a small weapons delivery platform seeking out targets of opportunity. Predators are not fully autonomous and I think the military requires a certified pilot at the controls even though taking off and landing are autonomous.

Bombers are the next aircraft to see deployment as UAV's... note the X-45 as an example. There will still be the need for manned bombers, but for the first wave air offensive where fixed targets such as military depots etc, need to be attacked I expect to see UAV's of the X-45/X-47 lineage delivering ordinance autonomously in much the same manner as cruise missiles do, with the exception that the bomber comes back home (hopefully).

Fighters are the last aircraft I expect to go UAV, and for much the same reasons as Broadsword20068 described... although comlinks between ground station and air vehicle are not as problematic as he sees.
With the technology available and forseen for the next 20 years or so - UAV fighters just are not practical and debatably feasible.

That's my take - I would have liked to go more in depth but time does not allow...

Natalie~

Well I am hoping to become a military pilot, so my job in the future better not go to a robot

:::sigh::: the ads for fighter pilots today: they show a pilot (or probably a model really) wearing the flight suit with the face mask and all that on, in a cockpit, and then they say something like, "This could be your office. U.S. Air Force" etc....or "Just a day at the office...etc..."

in 50 years those same ads will show some young guy sitting in a computerized room with a videogame control pad, and the ads say, "This could be your office...."

Originally posted by Broadsword20068

:::sigh::: the ads for fighter pilots today: they show a pilot (or probably a model really) wearing the flight suit with the face mask and all that on, in a cockpit, and then they say something like, "This could be your office. U.S. Air Force" etc....or "Just a day at the office...etc..."

Yep, those are really pilots....