5 ms·

Well, ideally the road has been prepared in advance. But fighter aircraft are much easier on runways than heavier planes (bombers/cargo) because there's typical

by chiph 3y ago

Well, ideally the road has been prepared in advance. But fighter aircraft are much easier on runways than heavier planes (bombers/cargo) because there's typically only one or two engines producing thrust. The F135-100 engine used in the F-35A puts out 43,000 foot-pounds (191 kN) when in afterburner. In comparison, the B-52 has eight engines, each of which produce 17,100 foot-pounds (76 kN) for a total of 136,800 foot pounds (608 kN), and the C-17 (which is rated for rough-field landings) has four engines, with a total of 161,760 foot-pounds (720 kN). But the most likely scenario is that larger planes will have their wings & engines extend beyond the sides of the pavement, and they'll tear up any grass and/or throw any gravel back behind them from the exhaust blast. The road surface is likely to be fine.

deleted 3y ago
[deleted]
wolverine876 3y ago
I am not a highway or materials expert, but I would expect that 191 kN in one spot is a lot worse than 76 kN in many spots? The cars and trucks spread over the entire highway add up to many more kN, I assume; it's the concentration of force that matters. Possibly, past a certain threshhold the road is destroyed and needs replacement, and 76 or 191 has the same outcome. Another way to think about it: Imagine you wanted to break up the road, intentionally, for some useful purpose - repaving, etc. If someone supplied a machine that blasted the road with 43,000 foot-pounds, I might expect that it was overkill.
- chiph 3y ago
  When planes that aren't VTOLs take off the thrust isn't perpendicular to the runway/road - it's mostly parallel. But what can happen is if there's a crack or gap in the road surface the wind could get under there and lift up chunks. Now you have a FOD problem for the next plane until someone can get out there and pick it up. But if the road was concrete and/or well-maintained, you're likely to be fine.

by chiph 3y ago

deleted 3y ago

[deleted]

wolverine876 3y ago

I am not a highway or materials expert, but I would expect that 191 kN in one spot is a lot worse than 76 kN in many spots? The cars and trucks spread over the entire highway add up to many more kN, I assume; it's the concentration of force that matters. Possibly, past a certain threshhold the road is destroyed and needs replacement, and 76 or 191 has the same outcome. Another way to think about it: Imagine you wanted to break up the road, intentionally, for some useful purpose - repaving, etc. If someone supplied a machine that blasted the road with 43,000 foot-pounds, I might expect that it was overkill.

chiph 3y ago
When planes that aren't VTOLs take off the thrust isn't perpendicular to the runway/road - it's mostly parallel. But what can happen is if there's a crack or gap in the road surface the wind could get under there and lift up chunks. Now you have a FOD problem for the next plane until someone can get out there and pick it up. But if the road was concrete and/or well-maintained, you're likely to be fine.