Forum: General F-35 Forum

Does the F-35 have the ability to operate from 800 m runways?

Espenjoh

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Yes. No. Maybe.

Well the B model certainly could

habu2 wrote:

Yes. No. Maybe.

That's great, just answered the question right there.

PhillyGuy wrote:

habu2 wrote:

Yes. No. Maybe.

That's great, just answered the question right there.

Well actually I did. The question did not specify a takeoff weight, altitude or temperature, let alone which version (A/B/C) so, depending on these factors, the answer could be "any of the above"...

Background for the question is that RNoAF is operating F-16`s from 800m RW`s. The gripen have also been operating from 800m RW. I dont know about takeoff weight, altitude or temperature, all i know is that RNoAF is regulary training from 800m airports, summer and winther (icy rw`s..), always with brake chute. As Norway have about 25 800m RW,s, i cant see that Norway will choose F35 if the aircraft cannot operate from these airports.
Espenjoh

I took the pictures below during practice landings on such a short runway.

RNoAF F-16B block 15 #693 lands at Leknes Airport (68 deg 5 min north) using drag chute in 1984/5. Just wanted to show a little scenery from the Lofoten islands in northern Norway.

RNoAF F-16B block 15 #693 lands at Leknes Airport (68 deg 5 min north) using drag its chute in 1984/5. This was part of an exercise using one of Norway’s many rural runways if the home base should be out of commission. The runway is only 800 meters, but that was not a problem using the chutes.

Of the three types RNoAF would use the F-35A. The shorter runways are typically meant to be used as alternative runways after the main bases are destroyed, so it is mainly the ability to land safely within 800 meters that is the key. Taking off should not be a problem, as they would then most likely be without much heavy armament.

I did ask once before on this forum if the F-35 would have space for a brake chute, but I got no good answer then. Does anybody know any better now?

lamoey wrote:

I took the pictures below during practice landings on such a short runway.

RNoAF F-16B block 15 #693 lands at Leknes Airport (68 deg 5 min north) using drag chute in 1984/5. Just wanted to show a little scenery from the Lofoten islands in northern Norway.

RNoAF F-16B block 15 #693 lands at Leknes Airport (68 deg 5 min north) using drag its chute in 1984/5. This was part of an exercise using one of Norway’s many rural runways if the home base should be out of commission. The runway is only 800 meters, but that was not a problem using the chutes.

Of the three types RNoAF would use the F-35A. The shorter runways are typically meant to be used as alternative runways after the main bases are destroyed, so it is mainly the ability to land safely within 800 meters that is the key. Taking off should not be a problem, as they would then most likely be without much heavy armament.

I did ask once before on this forum if the F-35 would have space for a brake chute, but I got no good answer then. Does anybody know any better now?

I would "assume" that the F-35C with its larger wing and flaps could take off and land it shorter distances than the F-35A?

Elite 1K Joined: Aug 19, 2004 - 09:19 AM Posts: 1092

Corsair... you're only taking into account lift. You have to take into account both lift, weight, and (to a much smaller extent when it comes to landing speeds) drag. If you made the assumption that the F-35's lift and drag coefficients are approximately equal to the F-16's, then you could approximate the touchdown speed and landing distance based on the F-35's reference area for various gross weights. The F-35 is a good deal heavier than the F-16, so the larger wing area sort of goes without saying.

Raptor_One wrote:

Corsair... you're only taking into account lift. You have to take into account both lift, weight, and (to a much smaller extent when it comes to landing speeds) drag. If you made the assumption that the F-35's lift and drag coefficients are approximately equal to the F-16's, then you could approximate the touchdown speed and landing distance based on the F-35's reference area for various gross weights. The F-35 is a good deal heavier than the F-16, so the larger wing area sort of goes without saying.

You bring up some valid points as always! That said, do we have any reliable data on take-off and landing distances for all three versions of the F-35 compared to the F-16? If, not what would be your best guess with the information available??? Rolling Eyes

Elite 1K Joined: Aug 19, 2004 - 09:19 AM Posts: 1092

What's up with the rolling eyes smiley? I seriously don't understand that sentiment in response to my post. I'll forget I saw it. Smile

Anyway, there's publically available data on the F-16's low speed aerodynamics (lift and drag coefficients vs. AoA). If you were to assign these values to the F-35 and run the proper calculations, you'd probably end up with a decent guess. I don't think the F-35's lift and drag coefficients are that much different than the F-16s in the landing AoA range. I could be wrong, but you'd be surprised how close the F-16 and F-16's aerodynamics are in the landing AoA range. The respective reference areas and gross weights account for most of the differences in landing performance (i.e. approach/touchdown speed and landing roll). As for best guess, I'm not able to just make a guess off the top of my head. Very few people would be able to do that. If you expect me to do a bunch of calculations using the F-16's low speed aerodynamics coupled with the F-35's reference area and empty weight plus some fuel fraction, forget about it. I'm not going to waste my time. No offense.

Raptor, we can make some back of the envelope calculations (professor terms). The F-35 is going to have a higher induced drag than the F-16, and low speed is where that dominates but I'd imagine that all the other drags (there's about 15 different drag types) are lower due to newer design and the fact that the airframe is 'slick'. The induced drag will be higher due to the enormous chord on the airframe thus a high aspect ratio. The F-35 (as well as the F-22) will have a really funny lift curve, with wings like theirs, stall won't hit very hard. That means you can put it up to really high AoA with fewer ill effects. I just learned this stuff in class this week Smile

. At any rate, I imagine that it would be able to take off in 800 meters... I just wouldn't recommend having any mountains right in front of airstrip.

Elite 1K Joined: Aug 19, 2004 - 09:19 AM Posts: 1092

When you're talking about the complete aircraft, you're talking about the CL and CD vs. AoA for the total aircraft. Induced drag, skin friction drag, form drag, bla bla bla... all that stuff is great for textbook theory, but your CFD simulation or wind tunnel tests are designed to give you "big" CL and CD for whatever condition. You're not concerned with Cd,this and Cd,that or Cl,this and Cl,that. You just want CL and CD vs. AoA for the complete aircraft. I'm not sure what the aspect ratio of the JSF is, but I know the F-16's is 3.0. I don't think the JSF's is much different. That being said, it's pretty difficult to tell whether the F-16 or F-35 will have superior aerodynamics in the low speed envelope (or high speed for that matter) based on general theory. Like I said, you'd be surprised how similar the F-15 and F-16's CL and CD curves are in the low to medium AoA range. And since neither the F-16 nor F-35 will be anywhere close to stalling on approach or touchdown, we don't really need to worry about what happens at high AoA in this case. I think you better check the F-35's aspect ratio though. I don't think it can be defined as high by any means. I'm pretty sure it's similar to the F-16's.

Forum: General F-35 Forum

F-35 take off and landing distance