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In the 1940's and 1950's, there were several tracked landing gear systems developed for the purpose of allowing landing on soft ground and/or using particularly heavy aircraft such as the B-36.

Are any such systems still in use and/or development?

(I have been searching and found quite a few examples but none in recent decades except for a proposal that suggests that it would be feasible to deploy modern improved tracked landing gear on C-130's, C-17's and 747s.)

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    $\begingroup$ The closest I can think of are skis for planes operating in the arctic/Antarctic. But those aren't tracks. $\endgroup$ – BSteinhurst Sep 30 '17 at 14:05
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For the first half century of manned flight, landing gears overwhelmingly had only a single, large wheel per leg. This was the cheapest and simplest way to ensure ground mobility, but ran into trouble when aircraft grew in size. When the XB-36 prototype started testing in 1946, only three airfields in the US were able to tolerate the 156 psi pressure of its single main wheels.

For operating from unprepared surfaces, tracked gears were the straightforward transfer from tank experience to landing gear design.

Tracked main gear on the XB-36 prototype

Tracked main gear on the XB-36 prototype (picture source)

However, another route which was tried at about the same time was to increase the number of wheels the aircraft rests upon. With hindsight, the multi-wheel way was the better solution and has prevailed. When used with large, low-pressure tires it does not exert significantly more ground pressure than a tracked gear.

Some early and rather extreme examples for the multi-wheel route include the Arado 232 four-engine tactical transport aircraft. Only 20 were produced, however.

Arado 232 close-up

Arado 232 from up close. No prize for guessing why it had the nickname "Tausendfüssler" (millipede) (picture source).

When it comes to designing large aircraft for soft field operations, the Ukrainian design bureau Antonov has unsurpassed experience. This comes to bear in the landing gear of the Antonov 124, shown below (source). When you have 24 wheels to spread the load out, even 400 tons might not be too heavy, especially when the tire pressure can be adjusted from the cockpit.

An-124 botched landing

An-124 in a botched landing. No worry, the gear will tolerate this kind of abuse, too.

Therefore, the research on tracked gears has come to an end shortly after it begun, and even the B-36 ended its days on a four-wheel bogie. Today, every large airplane has at least two wheels per leg for redundancy and sometimes a lot more.

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  • $\begingroup$ This is a great answer for the very large aircraft. Do you know what has become of the technology for the scenarios for small aircraft on bad terrain which prompted the various small aircraft tracked landing gear systems developed in the 1940's and later? $\endgroup$ – Dronz Oct 2 '17 at 2:47
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    $\begingroup$ @Dronz: As far as I know, tundra tires have won that race. $\endgroup$ – Peter Kämpf Oct 2 '17 at 6:34
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Magnesium Overcast, by Dennis R. Jenkins, is a history of the B-36, which covers the tracked landing gear experiments on pp.17-18. The XB-36 prototype was used for these experiments simply because it was a large and heavy aircraft that wasn't required for anything else at the time. One of his sources is an issue of the company's internal newsletter that's available online.

The problems with the tracked landing gear were that it added weight, about 5000lb for the XB-36, and that it made an unnerving screeching sound at high speed. Take-offs and landing were successful, but I suspect that it would have been substantially less durable than conventional undercarriage.

I doubt anyone is seriously considering the idea these days for large aircraft. Putting an unnecessary weight penalty on an aircraft is usually a poor idea, and making tactical landings in very large and heavy aircraft exposes that valuable asset to the enemy. It makes more sense to use tactical aircraft for tactical jobs.

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  • $\begingroup$ Thanks. Your reasoning is about huge systems, though, and there are several early examples of tracked landing gear which were on small aircraft (e.g. see the article at the first link in my question). 2) The one modern mention of tracked landing gear I did find was considering using them (and with large aircraft) though the presentation was not well edited and I'm not clear where it comes from. It expected there to be technological improvements available, but I didn't see a reference to them actually having been developed. $\endgroup$ – Dronz Oct 1 '17 at 4:07

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