Is that true? so temp and elevation decide runway length?

It's a big part of why the Wright brothers chose December at Kitty Hawk. Sand and prevailing winds were other factors. They would've never got off the ground in Phoenix.

 

Is that true? so temp and elevation decide runway length?

Yup... it all boils down to air density

But some planes are designed for such conditions

This might belong in the head scratching thread.

 

It's a big part of why the Wright brothers chose December at Kitty Hawk. Sand and prevailing winds were other factors. They would've never got off the ground in Phoenix.

This might belong in the head scratching thread.

Actually a little known fact is the Wrght Brothers were originally booked on a flight to Phoenix but due to inclement weather in Phoenix they were only able to get a flight to Charlotte NC with a short connecting flight to Kitty Hawk NC. The rest is, as they say, history.

Ron

 

Yes, and in most cases runway length is fixed. You can't take a short runway and make it longer so you work with what you have. There are considerations like weight and any head wind but temperature controlling air density is a very big key player in the game.

Ron

Also I would think there are limits on the speed an aircraft can reach while on the ground due to limitations in the landing gear. So even if the runway could be made longer it would just be a waste of real estate.

 

I would think there are limits on the speed an aircraft can reach while on the ground due to limitations in the landing gear.

I don't think that's the limiting factor. Airplanes are designed to go a lot faster than, "take off speed" (barely able to get enough lift). I can't imagine a set of landing gear designed for exactly the minimum take off speed. For instance, when they land, they are usually going faster than take off speed, and they often hit the ground a lot harder than the g-forces that happen when they leave the ground.

I'm not saying you can't land a plane with an engine failure, descending slower than take-off speed. I'm saying that isn't standard procedure. We have a couple of airplane aficionados here. Maybe one of them will contribute.

 

I don't think that's the limiting factor. Airplanes are designed to go a lot faster than, "take off speed" (barely able to get enough lift). I can't imagine a set of landing gear designed for exactly the minimum take off speed. For instance, when they land, they are usually going faster than take off speed, and they often hit the ground a lot harder than the g-forces that happen when they leave the ground.

I'm not saying you can't land a plane with an engine failure, descending slower than take-off speed. I'm saying that isn't standard procedure. We have a couple of airplane aficionados here. Maybe one of them will contribute.

Not what I was saying. I am sure the landing gear are way over built for both take off and landing. What I meant was (and just throwing figures out there). Say based off of atmospheric conditions, weight of aircraft etc. it would take the plane to get up to a speed of 500 knots for a safe take off. You would need a long enough runway to get to that speed for the aircraft to obtain that speed. Assuming you had a long enough runway for the plane to get to the required speed, I would think at some time you would exceed the speed at which the landing gear on the plane was designed to operate.

Tires alone have a rated speed. I am sure aircraft tires well exceed the typical automobile tire but they still have to have a rated max speed.

 

I would think at some time you would exceed the speed at which the landing gear on the plane was designed to operate.

That's what I have doubts about.
According to the Guiness Book of World Records, the lowest sea-level
pressure ever recorded was 25.69 inches in the storm Typhoon Tip.
http://www.faqs.org/qa/qa-20260.html
Let's go do Denver at 5000 ft.
24.9" Hg.
If Denver had a world record hurricane, the atmospheric pressure would be 20.59 inches of mercury.
That's about 2/3 of normal air density.
Gee, I wish an airplane guy would show up.

 

Gee, I wish an airplane guy @WBahn would show up.

Or @MikeML, I haven't seen him for a while...

 

Totally off topic but something I always found interesting is the physical stress an aircraft sees during an aircraft carrier arrested landing. This is just a single example but watch the struts collapse on landing and then return:

Ron

Now we can return to the weather. Oh yeah and weather related how about the pilots who fly through the walls of a hurricane? Talk about pressure change? Pretty cool stuff.

 

That's what I have doubts about.
According to the Guiness Book of World Records, the lowest sea-level
pressure ever recorded was 25.69 inches in the storm Typhoon Tip.
http://www.faqs.org/qa/qa-20260.html
Let's go do Denver at 5000 ft.
24.9" Hg.
If Denver had a world record hurricane, the atmospheric pressure would be 20.59 inches of mercury.
That's about 2/3 of normal air density.
Gee, I wish an airplane guy @WBahn would show up.

You need to add heat and weight to your formula.

And the runway is on Mt. Everest.

 

That's what I have doubts about.
According to the Guiness Book of World Records, the lowest sea-level
pressure ever recorded was 25.69 inches in the storm Typhoon Tip.
http://www.faqs.org/qa/qa-20260.html
Let's go do Denver at 5000 ft.
24.9" Hg.
If Denver had a world record hurricane, the atmospheric pressure would be 20.59 inches of mercury.
That's about 2/3 of normal air density.
Gee, I wish an airplane guy @WBahn would show up.

Rule of thumb is 1"hg. / 1000ft. We've been talking density altitude and related stuff over here if that helps:
https://forum.allaboutcircuits.com/threads/air-density-and-runway-length.137202/#post-1147738

 

http://www.latimes.com/local/lanow/la-me-endless-winter-20170617-story.html

"Skiers hit the slopes in bikini tops as California's endless winter endures a heat wave"

 

"Skiers hit the slopes in bikini tops as California's endless winter endures a heat wave"

Gee, I miss being young in California. That was great, and I knew it while I was doing it.

 

Gee, I miss being young in California. That was great, and I knew it while I was doing it.

It was great when I lived there too.

In Oregon there's always the chance for a great snowtan.

 

http://www.latimes.com/local/lanow/la-me-endless-winter-20170617-story.html

"Skiers hit the slopes in bikini tops as California's endless winter endures a heat wave"

Fond memories of my younger days living in Anaheim and San Diego but today you could not pay me enough to live in CA or for that matter NYC where I was born and raised. The climate was sweet though, the floods and forest fires were there during the 70 as they are today. Had a car as did my wife but I rode my bike pretty much year round. Standing in snow and looking down at the desert was pretty sweet.

Ron

 

today you could not pay me enough to live in CA or for that matter NYC where I was born and raised

how come?

 

how come?

Smog and over crowding.

 

Fond memories of my younger days living in Anaheim and San Diego but today you could not pay me enough to live in CA or for that matter NYC where I was born and raised. The climate was sweet though, the floods and forest fires were there during the 70 as they are today. Had a car as did my wife but I rode my bike pretty much year round. Standing in snow and looking down at the desert was pretty sweet.

Ron

I lived and worked in San Diego in the 70's. We would ride our bikes to Mt. Palomar or up and down 101 on the weekends. I left in 90 and have never regretted the move north.

 

OK. The answer is in from:

https://forum.allaboutcircuits.com/threads/air-density-and-runway-length.137202/#post-1147738

The landing gear has nothing to do with limiting take off speed but the brakes are a critical part of the runway length requirement. So,

I would think there are limits on the speed an aircraft can reach while on the ground due to limitations in the landing gear.

the answer is, "False".

 

I guess you could argue that brakes are a part of the landing gear.. There is probably a max tire/wheel speed too but doubtful that it would be limiting factor in normal use. Big jets have a max landing weight, though. It can be determined by structural as well as other factors and is why they dump fuel in an emergency return.