Nitrogen Tyre Inflation

[con-pilot]

There was another case of a main tire exploding the wheel well from overheating. It was in 1973 involving a Braniff 727. The aircraft was badly damaged and landed safely at Dulles Airport in Washington DC.

I have seen photos of the aircraft, but I cannot find any thing on line now about the incident.

Perhaps someone else will have better luck.

We did have ground distance charts in the 727 with waiting times, with the parking brake not set, that you had to follow if you had a long taxi, landing distance and estimated takeoff distances were including in the calculations. I can only remember a couple of times we were ever affected by the chart in the ten years I flew 727s, so it was not much of a limiting factor. If I remember correctly if you were parked for more than an hour there was no problem.

[18-Wheeler]

Using nitrogen in car tyres is a good thing

In racing car, yes maybe, but a complete waste of time and money in road cars. You never get road tyres anywhere near hot enough to get any benefit whatsoever from it.

[snrub]

Thanks for all your replies to the thread, I have found the information provided very helpful and informative.
snrub

[Old Smokey]

Please satisfy my curiosity. Is it true that Nitrogen inflation of tyres (tires) was an initiative of Ansett ANA, long long ago, or is it yet one more myth?

I suspect that John_Tullamarine may know the answer

Regards,

Old Smokey

[Flare-Idle]

SF6

The "best" inflation gas for aircraft tires from a performance point of view is sulfuric hexafluoride, SF6, a gas which is normally used in gas-insulated switchgear for high voltage applications (>100 kV) world wide. SF6 has excellent dielectric properties and its extinguishing capabilities are outstanding and outperforming every "competitor". Combine this with a really big molecule, Nitrogen can dust off....
Well, on the downside, SF6 is a "climate killer", so no good and therefore no large scale use in aircraft tires.
I stand to be corrected that the space shuttle still uses this gas in its tires ?

[RNAV.CAP]

sf6

hi!

but doesnt it vary with the amount of pressure relative to the proportion of manufacturer's allowable "time of compression" as allotted by the ISO standards?

rnv

[john_tullamarine]

Please satisfy my curiosity. Is it true that Nitrogen inflation of tyres (tires) was an initiative of Ansett ANA, long long ago, or is it yet one more myth?

I suspect that John_Tullamarine may know the answer

.. at a loss here. However, next historical do at Essendon I will track down one of the old chaps and see if he can throw any light on the question.

[Ex Cargo Clown]

Nitrogen molecules should be smaller than oxygen, MW=28 vs 32.

Not quite as simple as that !!!!

If it was, my life would be much easier !!!

[omniplasm]

O2 vs N2

Thanks for asking this question, had always meant to do so. Having always doubted the O2 bigger story in my mind dubious due to the MW being greater, have found and been corrected by (presuming it's true - sounds authentic):

www.getnitrogen.org/pdf/graham.pdf

I wouldn't think one expands more than another - physics hazy these days but I think the only time the ideal gas laws don't approximate reality is close to the liquid or sublimation points - certainly not relevant to O2 or N2 in these conditions

[Graybeard]

I asked around at Old Bold Pilots' breakfast this morning, and one ex-electrical mechanic remembers well his airline using nitrogen by the late 1960s, as he used the supply for his car tires.

Another OBP said the use of nitrogen in tires at the Bonneville Salt Flats goes back much further. How about Sir Malcolm Campbell?

GB

[Flash2001]

Even at my advanced age I learn something every day.

After an excellent landing you can use the airplane again!

[airfoilmod]

WOW

The Bluebird and Mickey Thompson's quad Pontiac. LSR. Em were the Days. Sorry, off thread.

[Ozgrade3]

This thread has got me thinking, as Im just about to get some new tyres for my car.

How much heat is generated at highway speeds in 60 serries tyres, if its true that with nitrogen you could increase the PSI by say 2 PSi without having them over inflate on the highway, there might be some merit for short trips in fuel economy, by having a slightly higher inflation with nitrogen.

Any idea on how much to go up by?

[onetrack]

Not precisely aircraft related... and some thread drift... but here's an interesting video that shows the results of welding... even for only a very short time... on an inflated light truck/pickup tyre.
This video was produced by a rim manufacturing company that became concerned about the practice of repairing steel rim cracks, in situ, on earthmovers.
At least one welder has been known to have been fatally injured by a tyre explosion caused by welding a cracked rim whilst the tyre was still inflated.
What I find interesting is how rapidly the internal fire in the tyre propagates, once started.
You can well imagine the damage caused by a tyre explosion/fire in a wheel well.

YouTube - Tire Explosion

[IFixPlanes]

The reason according the (still valid) AD 87-08-09:

To eliminate the possibility of a chemical reaction between atmospheric oxygen and volatile gases from the tire inner liner producing a tire explosion

[stilton]

'We did have ground distance charts in the 727 with waiting times, with the parking brake not set, that you had to follow if you had a long taxi, landing distance and estimated takeoff distances were including in the calculations. I can only remember a couple of times we were ever affected by the chart in the ten years I flew 727s, so it was not much of a limiting factor. If I remember correctly if you were parked for more than an hour there was no problem'




We avoided that problem by not having those charts !

[18-Wheeler]

How much heat is generated at highway speeds in 60 serries tyres, if its true that with nitrogen you could increase the PSI by say 2 PSi without having them over inflate on the highway, there might be some merit for short trips in fuel economy, by having a slightly higher inflation with nitrogen.

A complete waste of time, just stick with regular air.
Most of your tyre heat is generated by the brakes as well, not by the myth of the tyre sidewalls flexing and thus causing all the heat in the tyre.

[SNS3Guppy]

A complete waste of time, just stick with regular air.
Most of your tyre heat is generated by the brakes as well, not by the myth of the tyre sidewalls flexing and thus causing all the heat in the tyre.

This is untrue. While obviously brake use heats a brake and wheel assembly, sidewall flex accounts for significant heat rise. In large heavy aircraft, this can have a significant impact on brake energy determinations, just from taxiing the aircraft.

The fact is that in an automobile, the underinflation is the primary cause of blow-outs, largely due to heat rise. The reason for the heat rise is sidewall flex.

In large aircraft, sidewall flex, sans brake application, causes substantial heat rise during a long taxi. At maximum weights, one can heat brakes substantially without hardly any use, due to the tires getting hot during taxi and subsequent heat transfer.

[18-Wheeler]

All true, however I wasn't talking about aeroplanes I made it clear I was talking about car tyres. I also did not mention underinflation but again you have to be pretty low on pressure in a car tyre to get that and also going a fair rate of speed.
Thanks for the input, Mr Mitty.

[con-pilot]

Thanks for the input, Mr Mitty.

Don't even start it, Okay!