# Were WW2 American fighters designed to operate from dirt airstrips?

Fighter or fighter-bomber planes built in America during WW2, such as the P-36, P-39, P-47, P-51. Were these designed to takeoff and land on dirt airstrips?

My impression, and correct me if I'm wrong, is the following: Most airbases inside USA/Canada at this time had paved runways. At least half the fighters were designed to takeoff and land on carriers. Also, I think every single photo in wikipedia I've seen of these planes on the ground, is on a paved runway.

Now there is of course the Western Front in Europe, and some American aircraft did get sent to the USSR in lend-lease. I do not know if Britain and France had the luxury of paved runways at the time, but in Russia, most certainly did not. So you would think at least some of them had to had the strong undercarriage required for dirt airstrips. But I am not sure if they came that way or had to be modified after arriving in Europe.

One way to investigate this is to start looking at the airfields America had during WW2. Wikipedia has a giant category page for this, but even tho most of those pages have a history section, sadly I could find nothing about paved/unpaved. However, this photo from Midway shows paved runways, and I'm pretty sure Wheeler Airfield during Pearl Harbor had a paved runway too. If they were doing that in the middle of the Pacific, my guess is that most airbases in the 48 states and east/west coast mainland also had paved runways.

The reason I ask is because a stronger undercarriage requires more weight. Dirt landings require bigger wheels which take up room in the fuselage that could otherwise be used for fuel or bombs. Therefore, if paved surfaces are available, it makes sense to take advantage of it in your design. But as I said above, I can't be sure if paved surfaces would be available everywhere they intended to use them.

• American P-51's departing a dirt strip on Iwo Jima The comments about American airbases don't really have any bearing, I don't believe any missions departed airbases from the 48 states other than transport/relocation. – Ron Beyer Sep 30 '17 at 21:25
• Why do you think a dirt strip needs a stronger landing gear? Assuming it's graded, of course, and not just a fairly flat field. From my own (admittedly subjective) experience, a well-graded dirt strip seems a bit more forgiving than pavement. – jamesqf Oct 1 '17 at 5:05
• @jamesqf A previous question of mine, aviation.stackexchange.com/questions/19411/… , asked something like that. The answers I got seemed to indicate that bigger wheels and stronger undercarriage are required. – DrZ214 Oct 1 '17 at 12:52
• @jamesqf, Piper Cherokee weighs 975 kg and lands around 61 knots. That's tiny compared to WWII fighter—P-51 weighs 5,490 kg and lands around 113 knots. And that's not mentioning bombers—even B-17 weighs 29,700 kg (MTOW). While that's still small compared to modern fighters (F-22 weighs up to 38,000 kg!), it's much more than your typical GA SEP or light twin (Piper Seneca has MTOW 2,155 kg, still less than half of P-51). – Jan Hudec Oct 1 '17 at 20:38
• @jamesqf, yes, it is. But it was you who made an argument that single-engine planes today handle dirt just fine, which is irrelevant exactly because it is the wheel loading and not weight that matters (and the speeds, which also matter, are much lower). – Jan Hudec Oct 2 '17 at 6:13

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Opening theaters in the Pacific, for example, using fighters/bombers fitted with bush tires would not have been a good choice indeed. Maybe one pilot can pull it off. But not all, and certainly not the damaged planes.

As planes got heavier before WWII, and especially during WWII due to the massive engines and the all-metal construction, came the need for inflated tires, paved runways, hydraulic brakes...

... and the need for the Marston Mat. By using perforated steel planks, a runway can be built almost anywhere in a relatively short time (source).

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Above shows a North American P-51 taking off from Iwo Jima. Note the pattern on the ground. From far away in other B&W images the pattern does not become clear and the planes look as if they're using pure dirt runways.

Marston Mats were among the most important inventions of World War II (airspacemag.com).

As seen in your other question, How are modern jets modified to takeoff/land on a dirt runway?, Russian fighters are built with unpaved runways in mind. As are modern military transports. Transports have the luxury of space for many tires. But for jet fighters, it was the advances in tire manufacturing, which itself was due to the jet age that brought the swept wings and consequently the faster takeoff and landing speeds.

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Of course a humid tropical rainy island is different from a bone dry desert. The different soils and the water content affect their bearing and shear strengths. In North Africa, you may not need special reinforcements for the soil where its strength can be 4 times as high (think dry lakebeds).

• Wow, concrete runways. Musta been mighty expensive and hard to repair, but perhaps they did not have asphalt back then. And I see the Martson Matt is a nifty solution, like a prefabricated runway ready to go. Nice answer btw. – DrZ214 Sep 30 '17 at 22:00
• @DrZ214 "Wow, concrete runways. Musta been mighty expensive and hard to repair" - My late father spend his entire military service in WWII building concrete runways in the UK. In fact, many of them are still there having had no maintenance whatever for 70+ years, and it's too expensive to dig them up, even if the airfield has been abandoned and converted back to farm land. Of course they make good storage sites for farm machinery, etc - not to mention things like go-karting tracks! – alephzero Oct 1 '17 at 3:10
• The British repaired their runways after bombings fairly quickly, so I don't know where you're getting that reasoning. It wasn't like the concrete was reinforced or anything sophisticated? – toonarmycaptain Oct 1 '17 at 13:23
• @DrZ214, asphalt is not good surface for runways and never was. It is quite soft, so it requires good base and even then is prone to having tracks pressed in it. But many UK runways were actually brick. – Jan Hudec Oct 1 '17 at 19:54
• I arrived at Da Nang to PSP (Pierced steel Planking) as the only runway there. That use extended long after WWII. – Mike Brass Dec 23 '17 at 5:54

Early in the war, the RAF was using grass strips. Later in the war, the Allies tended to have prepared runways because they had much better supply and field engineering support than the Axis powers. In the UK, there were special runway teams, that would re-concrete a runway in sections, using fast curing concrete.

For more remote locations, the allies also had Marston Mat, a brilliant invention, the perforated steel planks used to cover dirt runways. Compact for transport, and assembly was very quick with a minimum of tools and equipment needed.

However, in very remote locations where supply wasn't so plentiful, dirt, crushed coral, or grass runways were used. This includes recently captured island bases, and China, which had a difficult supply situation when the Japanese closed the Ledo road, and supplies had to be flown in. My father told me stories about landing on hand built Chinese dirt runways in a P61 Black Widow, which touched down at around 110 kts. A bit bumpy.

Aside from being smoother, easing the load on the landing gear, prepared runways keep the dust and dirt down, which increases engine life. No air filters on those aircraft engines, so the less dust and debris that got sucked in, the longer the engine stayed in service.

• In the UK, there were special runway teams, that would re-concrete a runway in sections, using fast curing concrete. Can you link to more details? I would like to read more about that concrete and the procedure used. – DrZ214 Oct 3 '17 at 5:11
• The only reference I have comes from a couple of memoir books by bomber aircrew. The US Army had dedicated engineer teams that did nothing but build and repair concrete runways, populated largely by black soldiers (this still being a segregated army at the time). The bomber crews noted that these engineers did a much better job at keeping the runways smooth than the British teams that originally built them. – tj1000 Jan 13 '18 at 0:33

In 1939 most military airfields were grass strips, since there were no four-engined bombers, and most warplanes were capable of landing on roads or meadows in emergency (as instructors say, "You can land anywhere -once.")

With the outbreak of war, aircraft designers needed more powerful engines (with larger, more sensitive air intakes) and longer take-off distances (obviously concrete, being smoother than grass. works better here). Commanders were also less keen on their air support taking a day off because it was raining. So suddenly, all over Europe and other combat areas, new airfields were being built, and old ones refitted, with concrete runways; these were often called "all-weather airfields" and could be strategic objectives (this Wikipedia page refers to a unit being sent to capture the only all-weather airfield in Burma).

Though the military had construction units (the British Pioneer Corps and the US Corps of Engineers), they were often overstretched, and cililian contractors had to be used. One airfield near where I live, RAF Beaulieu, was built by local labourers. Having left school at 14, too young to be called up, they did their bit by joining construction companies for a few years, and indeed the airfield opened on time in 1941. They were, however, obviously inexperienced (both the young workers and the managers who might have never seen a concrete runway, let alone built one), and working under a lot of pressure for both time and cost. Interestingly, though the RAF squadrons who used the airfield made no complaint, the USAAF pilots found that it was not up to the standards they were used to (and it rained a lot more than back home, which also degraded performance). They did not receive much sympathy from the builders who had dodged machine-gun fire. (Some memoirs have been published, but not on the internet; a few of them are still around and telling stories in the pub).

http://warbirdsnews.com/warbirds-news/poor-lambs-corsairs-baa-baa-blacksheep.html I enjoyed watching this show as a youngster, with Corsairs flying out of what looked like a dirt airstrip in the Channel Isands. Filming apparently took place at Indian Dunes Airfield in CA. Pictures of the set at the bottom of the site sure seem to show a dirt strip.

Other links about Indian Dunes Airfield discuss it being turned into farmland, I don't think that would have been done if it was paved. Of course, if the land was worth enough, anything goes I guess.

At more sophisticated airbases, yes. However plenty of bases used grass fields or strips as well as dirt strips plowed flat with a dozer blade.

• Can you give a list of a few airbases of the USA that had unpaved runways? I haven't been able to find any. – DrZ214 Oct 2 '17 at 5:09
• Maybe Edwards AAF at Muroc. There were plenty in Great Britain and Germany, though. – Carlo Felicione Oct 2 '17 at 14:54
• @CarloFelicione: Edwards still has unpaved runways (albeit also some paved runways) even today. – Sean May 29 at 1:11