Forum: F-35 milestones

habu2 wrote:

One taxi test down, two to go before first flight. Thumb

Hey, this is EXCELLENT news! Congratulations! Any pictures or additional data available???

F-16.net Sponsor

First pictures will probably show up here and/or here

Some of you may remember a thread here on f-16.net which linked to an F-35 engine run video on youtube. That was an official Lockheed video but was not placed on youtube by Lockheed. I thought they (Lockheed) might be p*ssed about that but I now understand they may try to use youtube exposure to their advantage. By that I mean LM may post first flight videos directly to youtube. That's my read on it anyway, nothing official. We will know in less than a week.....

habu2 wrote:

First pictures will probably show up here and/or here

Some of you may remember a thread here on f-16.net which linked to an F-35 engine run video on youtube. That was an official Lockheed video but was not placed on youtube by Lockheed. I thought they (Lockheed) might be p*ssed about that but I now understand they may try to use youtube exposure to their advantage. By that I mean LM may post first flight videos directly to youtube. That's my read on it anyway, nothing official. We will know in less than a week.....

I was the one that posted that video to youtube. I posted it there because it was posted on the JSF website for the public domain, but some users were having problems viewing the video. If I am not allowed to post videos from the jsf site again, please let me know and I'll be fine with it (or take down the one I already posted). That thread is here by the way for reference --> http://www.f-16.net/f-16_forum_viewtopic-t-6477.html

Anyways, I'm glad the first taxi went well. I hope the rest goes well too! Very Happy

habu2 wrote:

One taxi test down, two to go before first flight. Thumb

Here's the info I heard (just a tad more detail) -- "... performed Ramp and 30 knot taxi tests [12/7]. [12/8] ... to do 65 and 80 knot taxi tests and on the 9th they are to do 110 knot taxi tests." -- I don't think any of that is confidential...

Ciao,
Smithsguy

habu2 wrote:

One taxi test down, two to go before first flight. Thumb

Dumb question: Will there be any media there to capture the first flight? Just curious to know how long it would be before there is any footage of the aircrafts first flight available to the general populace.

tiedyed wrote:

Dumb question: Will there be any media there to capture the first flight?

No.

All photo/video is LM only. Anything else is from "the other side of the fence."

First low speed taxi photo I've [Link pending approval]

[Link pending approval]+First+Lockheed+Martin+F-35+Lightning+II+makes+first+[Link pending approval]

Bigger photo [Link pending approval]

[Link pending approval]

Hey folks,

I heard wind postponed today's taxi tests.

Ciao,
Smithsguy

Monday's 60 kt test was successful.

Tuesday should see the 85 kt test, possibly 110 kt as well.

Here is a shot I took from Monday . . .

The F-35 Lightning II rolls out on December 7th, 2006 at NAS Fort Worth to conduct taxi tests.

KeithTCU82 wrote:

Here is a shot I took from Monday . . .

The F-35 Lightning II rolls out on December 7th, 2006 at NAS Fort Worth to conduct taxi tests.

Bravo! Congratulations on an excellent shot. A couple of points that have not been often discussed: the F-35 is a very "tall" airplane, with a very tall landing gear and an enormous amount of room under the fuselage. Compare to the F-22, which sits very close to the ground. In fact, the F-35, which is a smaller aircraft and has much smaller vertical tail surfaces, is taller than an F-22 on the ground. Why is that? I suspect it has something to do with the STOVL requirements for the F-35B. However, this should make maintaining this baby that much harder. One of the great advantages of the F-22 is precisely that it sits so close to the ground, at least from a maintenance standpoint.

Further, the front landing gear door is HUGE. I suspect we'll see a different door on the next aircraft to roll off the line (remember, this baby is more a prototype than a production-representative test vehicle, as it was built before all the weight-saving measures were put in place by LM).

Now, the vertical tail surfaces are tiny compared to those of the Raptor, indicating that maneuverability will be drastically limited compared to the F-22. Same is true of the horizontal tails. LM is claiming F-16-like maneuverability, but it will be interesting to see if they really can achieve that with what appear to be small tail surfaces (you should all know by now that I am one of the F-35's staunchest advocates so please don't accuse me of being unduly negative--I may be rooting for the F-35, but I am also an objective observer and not a mere "fanboy").

Finally, is the F-35 the only modern single-engined fighter with twin tails? I cannot remember any other off the top of my head. That may also explain their small size: for a single-engined fighter, smaller twin tails may be sufficient to achieve acceptable lateral stability.

Anyway, nice pic. Look forward to first flight!

Quote:

Further, the front landing gear door is HUGE. I suspect we'll see a different door on the next aircraft to roll off the line (remember, this baby is more a prototype than a production-representative test vehicle, as it was built before all the weight-saving measures were put in place by LM).

Now, the vertical tail surfaces are tiny compared to those of the Raptor, indicating that maneuverability will be drastically limited compared to the F-22.

As part of the weight saving campaign for the F-35 the front landing gear door was changed to two smaller doors. As a consequence the vertical tails could be reduced saving a lot of weight. I don't know if the first aircraft have the smaller tail though.

lamoey wrote:

Quote:

Further, the front landing gear door is HUGE. I suspect we'll see a different door on the next aircraft to roll off the line (remember, this baby is more a prototype than a production-representative test vehicle, as it was built before all the weight-saving measures were put in place by LM).

Now, the vertical tail surfaces are tiny compared to those of the Raptor, indicating that maneuverability will be drastically limited compared to the F-22.

As part of the weight saving campaign for the F-35 the front landing gear door was changed to two smaller doors. As a consequence the vertical tails could be reduced saving a lot of weight. I don't know if the first aircraft have the smaller tail though.

The big landing gear door will act like a sail in crosswinds, particularly on approach. This is why making two smaller doors allows them to reduce the vertical stabilizer size. My understanding is that the fin change will not appear until the next airframe (AB-1, the first STOVL prototype), although that information is second-hand.

I don't know why the previous poster equates vertical stabilizer to maneuverability. A jet fighter does its manuevering primarily in roll and pitch. Roll authority is in the ailerons (and sometimes the horizontal stabilizer) and pitch is a combination of lifting surface and elevators). Since the flight computer does turn coordination (the useful rudder operation in ACM), I'm told modern pilots are taught to plant their feet flat on the cockpit floor when dogfighting, safely away from the rudder pedals.

-- Shaken - out --

Shaken wrote:

I don't know why the previous poster equates vertical stabilizer to maneuverability. A jet fighter does its manuevering primarily in roll and pitch. Roll authority is in the ailerons (and sometimes the horizontal stabilizer) and pitch is a combination of lifting surface and elevators). Since the flight computer does turn coordination (the useful rudder operation in ACM), I'm told modern pilots are taught to plant their feet flat on the cockpit floor when dogfighting, safely away from the rudder pedals.

Correct me if I'm wrong, but the canted tails of the F-18 are canted precisely to retain yaw control authority at high AOA. The Raptor's tails are canted principally for RCS reasons, but the enormous rudders are necessary for yaw control at high AOA, which directly impacts an airplane's ability to point its nose at a target. That, at least, is my understanding, but I may be wrong.

Shaken wrote:

lamoey wrote:

Quote:

Further, the front landing gear door is HUGE. I suspect we'll see a different door on the next aircraft to roll off the line (remember, this baby is more a prototype than a production-representative test vehicle, as it was built before all the weight-saving measures were put in place by LM).

Now, the vertical tail surfaces are tiny compared to those of the Raptor, indicating that maneuverability will be drastically limited compared to the F-22.

As part of the weight saving campaign for the F-35 the front landing gear door was changed to two smaller doors. As a consequence the vertical tails could be reduced saving a lot of weight. I don't know if the first aircraft have the smaller tail though.

The big landing gear door will act like a sail in crosswinds, particularly on approach. This is why making two smaller doors allows them to reduce the vertical stabilizer size. My understanding is that the fin change will not appear until the next airframe (AB-1, the first STOVL prototype), although that information is second-hand.

I don't know why the previous poster equates vertical stabilizer to maneuverability. A jet fighter does its manuevering primarily in roll and pitch. Roll authority is in the ailerons (and sometimes the horizontal stabilizer) and pitch is a combination of lifting surface and elevators). Since the flight computer does turn coordination (the useful rudder operation in ACM), I'm told modern pilots are taught to plant their feet flat on the cockpit floor when dogfighting, safely away from the rudder pedals.

-- Shaken - out --

Yes, vertical tails and rudders are typically sized based on a critical landing condition rather than up and away maneuverability. Typically, they are sized based on landing with some combination of crosswind, mass property asymmetry, and failures state (including engine(s) failures for multi-engine a/c).
As to your other point (regarding roll and pitch being the primary axes for maneuvering) that is true, but doesn't quite tell the whole story.
Without getting too far into the nitty-gritty, it comes down to roll coordination. Regardless of whether the coordination command is coming from the pilot or the FLCS, it (usually) winds up at the same place - the rudder.
For 'conventional' aircraft configurations, in most of the 'conventional' envelope (moderate-to-high speed, normal AOAs) the roll rate available is limited by available roll control power (i.e. aileron authority) or other factors (structural loads, etc) rather than the rudder (i.e. coordination requires comparatively little rudder).
Once you begin to expand into higher AOA's, though, the situation changes. Beginning somewhere in the low 20's of AOA (rough, typical numbers given) and extending into the mid 30's, the rudder rapidly loses effectiveness. The wing surfaces (aileron, TEF's) tend to hold their effectiveness somewhat better. At some point, the roll surfaces are able to create more moment than the rudder can effectively coordinate. At that point, the roll rate commanded has to be reduced (i.e. not all available aileron used) to avoid rudder saturation, which would lead to excessive sideslip, sloppiness, and unpredictability in rolls.

Getting back to the comment:

Quote:

Now, the vertical tail surfaces are tiny compared to those of the Raptor, indicating that maneuverability will be drastically limited compared to the F-22.

Above the mid 30's in AOA, the rudders become completely ineffective due to blanking from the wing, so the next-best control pair (usually differential horizontal tail) must be used for yaw control. So, in this regard, if one is talking maneuvers at very high AOA (things like Cobras, J-turns, etc, or 'helicopters') rudder size becomes effectively irrelevant. Not that there aren't other limiting factors......

Forum: F-35 milestones

F-35 first flight