It can move forward, back, and side-to-side two feet off the ground if the pilot so chooses. There isn't some "magical" altitude at which they say "ok, we're at XX feet, so its only straight down from here". They have to be able to have that ability to fine-tune the parking/landing position of the aircraft.
_________________ Remember that a lone amateur built the Ark. A large group of professionals built the Titanic.
mcashe
Posted: Apr 05, 2007 - 10:50 PM
Regular User
Joined: Jul 21, 2004
Posts: 27
Status: Offline
wow. and i thought the movie true lies was corny when the governator straddled a hovering harrier. i would think that x35b would make that street a little unbearable for the people in the area with the heat that engine is putting out. cooling system not withstanding
donk14N
Posted: Apr 06, 2007 - 12:16 AM
Frequent Poster
Joined: Nov 06, 2006
Posts: 62
Status: Offline
I was really looking forward to this movie (loving the prior three), until I saw what looked like Bruno jumping off the horizontal stabilizer of the JSF at the end of the preview. For shame.
Shonuff
Posted: Apr 06, 2007 - 04:47 AM
Regular User
Joined: May 10, 2005
Posts: 37
Status: Offline
awww.... the bastards blew it up...
nzenthusiast
Posted: Apr 06, 2007 - 10:35 AM
Frequent Poster
Joined: Jan 13, 2005
Posts: 84
Status: Offline
Well its good PR (public relations) even if its usage is unrealistic (the best case of PR was top gun in my opinion)
Driver
Posted: Apr 06, 2007 - 07:02 PM
Active member
Joined: Aug 13, 2005
Posts: 155
Status: Offline
VPRGUY wrote:
It can move forward, back, and side-to-side two feet off the ground if the pilot so chooses. There isn't some "magical" altitude at which they say "ok, we're at XX feet, so its only straight down from here". They have to be able to have that ability to fine-tune the parking/landing position of the aircraft.
I wonder for the simple reason: For a JSF to go forward during hover, it would need to put it's nose down to get speed due to the fact that the engine is facing down. Because of gravity that means the jet will go nose down into the ground so the only way a JSF could do that is by either by having enough power comming out of the engines to compensate meaning it would gradually rise or by removing all friction. #1 is a no can do since th jet is under a bridge #2 is a no can do becuase simply we can't.
Raptor_claw
Posted: Apr 06, 2007 - 07:32 PM
Active member
Joined: Sep 29, 2006
Posts: 175
Status: Offline
Driver wrote:
... For a JSF to go forward during hover, it would need to put it's nose down to get speed due to the fact that the engine is facing down. Because of gravity that means the jet will go nose down into the ground
Hovering is not flying (more accurately, it's not conventional 'wingborne' flight).
It's a completely different set of mechanics than 'normal' flight, where you might lower your nose (to reduce drag and/or altitude) to increase speed.
In the hover mode, all the forces on the aircraft (other than gravity) are provided by thrust (jet, lift fan, and roll post). To move forward from a pure hover, the net thrust vector is 'repointed' so that it's not purely straight down, but has a forward component. This is accomplished via changes to the deflection angles of the nozzle and the lift fan vanes, and use of the roll posts, as needed.
sprstdlyscottsmn
Posted: Apr 07, 2007 - 08:41 PM
Veteran
Joined: Mar 10, 2006
Posts: 340
Status: Offline
thats true, the lift fan vane especially has a wide(relatively) range of motion allowing for a certain degree of velocity shift with no attitude change.
_________________ James,
-Pilot
-Aerospace Engineer
-Army Medic (WTF?)
dwightlooi
Posted: Apr 07, 2007 - 10:05 PM
Elite
Joined: Aug 02, 2006
Posts: 909
Status: Offline
The F-35B in hover mode can move up, down, left, right, forward, backwards, as well as rotate left and right. Thats the basic degree of freedom needed to land the darn thing on an LHA/LHD. Even though vertical flight is typical used only for landing, the F-35 can also take off vertically if asked to do so. The problem is that doing so doesn't allow for much payload. The maximum total hover thrust is about 17.9 tons. The F-35B weighs about 14.5 tons, so that leaves about 3.4 tons (~7,500 lbs) for payload. That is enough for half a tank of gas (6.4/2 = 3.2 tons) or maybe 1/3 the fuel load, 2 x 1000 pounders and a pair of AMRAAMs. For the same reasons, the harrier typically do not take off vertically either because it wouldn't be able to carry much if it did so.
asiatrails
Posted: Apr 08, 2007 - 05:42 AM
Elite
Joined: Aug 30, 2005
Posts: 605
Location: San Antonio
Status: Offline
dwightlooi wrote:
The F-35B in hover mode can move up, down, left, right, forward, backwards, as well as rotate left and right. Thats the basic degree of freedom needed to land the darn thing on an LHA/LHD. Even though vertical flight is typical used only for landing, the F-35 can also take off vertically if asked to do so. The problem is that doing so doesn't allow for much payload. The maximum total hover thrust is about 17.9 tons. The F-35B weighs about 14.5 tons, so that leaves about 3.4 tons (~7,500 lbs) for payload. That is enough for half a tank of gas (6.4/2 = 3.2 tons) or maybe 1/3 the fuel load, 2 x 1000 pounders and a pair of AMRAAMs. For the same reasons, the harrier typically do not take off vertically either because it wouldn't be able to carry much if it did so.
Pretty well correct, this is why everyone, except the USMC has ski jumps on their ships.
During the flight test program of the AV8B we cleared the Harrier envelope to -20 Kts in the hover and demonstrated (inadvertently) in excess of -35 Kts. The biggest issue with the Harrier is the hot day bring back capability; you do not want to dump a high $$ store just because you are too heavy to come aboard.
Search
Register
Log in to check your private messages
Forum Guidelines
