This Spitfire ALMOST Went SUPERSONIC - The British WW2 Fighter That Almost Broke The Sound Barrier 

"I'm somehow back at 40000 feet, without an engine having blacked out and come out of a fatal dive. However, no need to bail out, I have these enormous balls of steel that will help me land the Spitfire Superglider safely". Respect.

My great Grandfather flew Typhoons in 1944-5 he said he first flew at a indicated 590mph in a Spitfire mk9 in 1943 whilst diving to escape three 109Fs and the Typhoon regularly exceeded 600mph indicated in a dive, he lived until he was 82years old despite two crash landings and being shot down three times between 1943-45

According to Eric ‘Winkle’ Brown’s book ‘Wings On My Sleeve’, the dive undertaken by Tony Martindale that resulted in the loss of the prop & reduction gear which left the Spitfire with slightly swept wings was his second dive that day. The first reached M0.91 and he’d had to apply 80lb of force to the stick to recover from the manoeuvre. Brown stated that he’d had to use both hands to apply 60lb of pull in his own M0.86 dive and wouldn’t be able to exceed that so Martindale took it further as he was a much larger and stronger chap. Incidentally, it’s not surprising that Martindale passed out as his weight-reduced Spit hurtled back up to 40,000’ ~ he pulled 11G in doing so.

I've seen an old interview in which General Chuck Yeager himself said that he wasn't the first to break the sound barrier, he readily admitted that he was the first to break he sound barrier IN LEVEL FLIGHT. He absolutely agreed that a few pilots had indeed broken the sound barrier in souped up piston engine planes in steep dives before he did it in the X-1 on October 14, 1947.

I am not qualified to comment on the reliability of the airspeed readings but I can state categorically that there is no sound like a Rolls-Royce Merlin on song.

The photo of what was left of that spitfire is amazing, how did he land that warped pile of junk?truly a gifted pilot

This evening I watched the Antiques Roadshow. A gentleman on there displayed his Father's medals and log book with aerial reconnaisance photos from ww2. Apparently low level photos were only safely obtained by high speed dives. The aircraft had no armament. They were very brave.

Almost, there was a strong feeling that more than 1 went through it & survived. My father flew a Mustang Mk111 for the RAF & the Spits were considerably faster in a dive. His whole plane was shaking so much he couldn’t read the instruments. More than 1 Spit literally broke apart too.

If it really reached that speed or not , what surley impresses me most is the bravery that those men showed by trying these trials, and considering the tech in those years it was really something.

What many people do not understand is that the local Speed of Sound is dependant on Temperature. Air Density has almost no influence on S of S. At 40,000 ft, the air temp is likely to be in the vicinity of -40 degrees, so the S of S is lower than at ground level, (763MPH @ 15 degrees C). Therefore, for a given groundspeed, the Mach number will be higher at higher altitude, due to the lower S of S, which changes by about 1.3 MPH per degree C. At 40,000ft the local S of S is likely to be in the vicinity of 690MPH. If the plane descends at a constant airspeed, the Mach number will fall as the local temp and local S of S rise. Many pilots were saved from high speed compressibility in a dive as the Mach number fell with the rise in local S of S.

Notice in the photograph of Sq Lr Martindale and three others, the most famous test pilot of all time Captain Eric Melrose Brown RN who also received the AFC for his momentous work on aircraft carrier aviation, which included the first landing of a twin engined bomber onto a carrier, the Mosquito, and after the war the first landing, and take off of a jet propelled aircraft, and recorded some 2700 carrier landings in his illustrious career .

Supermarine developed an even faster model. Featuring an even higher performance version of the Griffin engine and the bubble canopy fuselage, this version - now known as the 'Spiteful' - featured a laminar-flow wing similar to that of the P-51 Mustang. This avoided the lack of rigidity that Mitchell's elliptical wing suffered at very high speed, and helped to reduce the problem of compressibility as speed approached the sound barrier. Sadly, with the onset of the jet age, very few were made.

Yes, I'm so pleased your research was thorough. Someone else's earlier video never mentioned (beyonf Tobin) Martindale's M= 0.92 (p.50 in Capt.Brown's book 'The Miles M.52') and I also have known about Powle's 1952 incident. I do believe it because that version of the Spitfire wing was very suited to high speed - not the original shape nor the later Spiteful wing. In testing for the Miles M.52, a Miles Falcon was given a bi-convex wing, ultra thin ('the Gillette Falcon'), nearly elliptical, but with wing tips cut off diagonally along the line of the outer shock wave. Presumably, the elliptical wing of the Spitfire, though not solid was thin and was almost within the V-shaped shock wave from the aircraft's nose. PS. tests were later done on an all-moving tailplane for the M.52...on a Spitfire.

The pilots notes on the Antiques Roadshow last weekend showed that his lightweight unarmed photo reconnaissance Spitfire reached close to 600mph in a dive. That means the airframe was better than nearly all the early jet aircraft. It certainly had a better limiting Mach number than the later P51 Mustang. The Spitfire was better than it had any right to be in this respect.

The stripped photoreconisence Spitfire flight is recounted in Eric "Winkle" Brown's marvellous book "Sings on my Sleeve" A must read for any aviation enthusiast!

I'm impressed that these planes can take off at all, what with the massive pair of bollocks slowing them down. The greatest generation.

Very accurate portrayal of these pilots exploits . And cements how fabulous an aircraft the Spitfire was ! Thanks .

I live in Newmarket suffolk , nearby is the old RAF Duxford aerodrome and new museum , and have the privilege of hearing that merlin engine sound and seeing that beautiful R. J Mitchel designed aircraft regularly - and it stops me dead in my tracks every single time.

I would call the Spitfire the Bradman of propellor flight. Both were the greatest of all time, both inspired their nations like no other and both had an average just under the magical number. Which is fitting for humble heroes.

As a USN/USMC flight test engineer I think they made the correct decision. While aircraft flown out of Farnborough had precisely calibrated airspeed equipment a fleet aircraft would have a much more significant deviation in its equipment. Fleet instruments have no need to be precisely calibrated which would be beyond the capabilities of the local repair facilities. The .03 difference in Mach number is easily within the margin of error for fleet instruments IMHO.

Thank you for covering this episode on the Spitfire.

A guy that I worked with had been in the RAF Regiment in the war, guarding air bases. At one base used by the USAAF, a Thunderbolt pilot was doing acrobatics, and put his aircraft into a steep dive; when he landed the wings had ripped out of the fuselage.

The Spitfire was a Design Classic, never was so much owed to one man, and that man was R. J. Mitchell, a crying shame that he died of Cancer before he ever saw his masterpiece fly in action.

Great video, well done. Such an amazing aircraft the Spitfire was- perhaps the greatest of them all. IMO more recognition should be awarded posthumously to its designer R J Mitchell who in fact sacrificed any prospects of his own recovery to ensure this masterpiece was conceived

My Grandfather was with 41 squadron when they were equipped with the Mk 12 spit, one of the tasks assigned to them was AA gunnery searchlight/ radar calibration, which involved flying straight and level at 20,000 feet for 20 minutes , after calibration had been completed (notified by radio), it was fun time. Full throttle, stand it on its nose and see how fast the 'blighter' would go , resulting in the ASI indicator needle hitting the stop. the control surfaces getting very heavy and after landing, a bo**ocking from the CO, " what the hell did you do to that aircraft, what was that noise" . My Grandfather was adamant the his colleagues told him they heard a bang or a boom, not that he did or that they would have known what it was. This little 'procedure' was banned after the odd "airscrew came off". Later in his career doing high speed dives in Meteors and Vampires my Grandfather noted and much later told me that the spit 12 was a damn sight nicer at those higher speeds. I always found it hard to believe that he broke the sound barrier in a Spit but did not wish to question him too much out of respect.

As someone that absolutely loves the Spitfire and its history. I think you have done a fair job telling the story about the near mach speed. But to anyone that isn't aware of these events in history, I think it would have been nice to have heard you mention the other aircraft that were tested for the same purpose, but were concluded as not up to the job. One that stands out in my mind is the P51 Mustang. Always compared with the Spitfire due to it's Merlin engine. (British Specification, may I add) . I know you said very briefly about it towards the end. But the Spitfire proved more stable and the fact it could glide, speaks volumes for its design.

Nice one! I think the Spit broke the supersonic barrier, i wonder what other amazing aircraft RJ Michell would have come up with had he lived ?

Great Movie ! Thanks. Your Northumberland / Durham accent reminds me that i fell a little bit in love with every girl who ever spoke with me using that lovely accent. Thanks for the memory.

A Yank here and I must say that the Bravery of these pilots is unmatched and it could not have been done with out the technicans and scientists on the group ! All of these people deserve medals too ! BYW Have any propeller aircraft ever broken the Sound Barrier ????

Great video, well done, very good commentary, 👍.

I think he managed that speed. Higher altitudes mean thinner atmosphere means less friction. I reckon he clocked that speed while still quite high up in his dive

I reckon he did hit Mach 0.96! I like these videos, keep up the good work!

Aaaaaah the sweet sound of Merlin. Coupled with the smell even better!

According to german accounts a photo reconnaissance spitfire did hit the mach 1.0 barrier and it is assumed it was as fast as mach 1.01. The Spitfire came under attack from ME-109s over france and dived to escape, the ilot flew low enough to be fairly safe from most if not all of the area anit air defenses. A german officer had reported seeing the spitfire fly low into a canal, and infact flew under two bridges, having times in his report the times indicated that the spitfire had mach 1.0. The same spitfire actually broke appart with the pilot barely surviving but the pilot had managed to destroy much of his photo equimpent, and when taken into custody he was saluted and given extra good tratement by the luftwaffe for his "heroic speed" as they called it. I did read later that aviation experts have gone over the various reports at the time and found that the spirfire could not have travelled that fast, but they do belive it may have been as much as mach 0.75.

As well as the advantage of thin wings, I've always thought that the design of the Spitfire fuselage produced natural area ruling that gave drag reduction at very high speed.

Excellent, no bloody annoying music. Interesting video

Best program Ant and Dec have ever done. Great upload all joking aside. Many thanks 👍

"This research helped Chuck Yeager break the sound barrier in the Bell X1". That and the fact that we mysteriously cancelled our ready to go supersonic aircraft and then obligingly let the Americans look it over so that they could copy the tail plane!

'Winkle' brown and the RAE Test Pilots Tested the P-47,P-38 & P-51 at their Maximum dive speeds. So as to determine the Max Mach Number that could be used in operational conditions. The P-47 and P-38 had surprisingly low attainable Mach numbers. They Advised the USAAF to concentrate on P-51 production. and procurement.

The P47 was frequently use at very high speeds (probably close to 1000km/h) during hunt on Me 262's over germany (Spitfires was nevers use because had a low range) , and was able to fly FASTER in dive as a me 262 who was limited at ~950km/h from tail design defects who make this aircraft totaly uncontrolable in transsonic speeds...but "almost break the sound barrier" for the Spitfire is a false assertion: the sound speed (mach 1) is at 1224km/h at sea level and 1153km/h at 5000m altitude and the speedometer use on the WW2 aircrafts was unable to measure the real speed over 900km/h...i did use metric for the numbers because mph is not international allowed , but only Knots = nautical miles per hour (who is metric), or km/h) and mph are only use from Brits and US, never from continental europe countries...

Thanks for posting. It's nice to hear a northern accent. Both my folks are from Sunderland. 🙂

Quite common for Tempest pilots to exceed 560mph in dives, but i find 690 very hard to swallow. 606 is hard enough considering the weight & power. Spits are just not strong enough, damn lucky the wings didn't tear off. I seem to remember Alex Henshaw saying he would put them into a 450 max speed dive, at which point they were out of control.

I loved it when Thrust SSC broke the sound barrier on the ground. We need to push further and faster. It's what makes us move forward. We were always ground breakers in speed. Look at Concord utterly magnificent. What a plane to be proud of. 1 crash to be blamed on another planes debris on the runway. NOT CONCORDS FAULT.

They were lucky that they were able to pull out of the dive.

Spitfires constantly went over their supposed top speed in Dives with emergency super charger boost activated

Very good video very interesting great pictures of the spitfire inside the cookpit , well done all

Well done , excellent video.

Love your videos man! Absolutely fascinating! So well put together please don’t ever stop.

Great video thank you. Reconnaissance version of the Spitfire reminds me of the great BBC documentary with Dan Snow about RAF Medmenhan and operation Crossbow.

With regards to the RAF Kai Tak Spitfire, it would be interesting to note whether the Speedometers where calibrated to National Standards and what was the accuracy and repeatability of them. If it was the case that the gauge was calibrated and the Spitfire had been just shipped from the factory we could say that this was indeed the new record. Usually certain gauges are classed accurate to +/- X mph or as a +/- percentage when manufactured, given the vibrations these aircraft would go through, gauge inaccuracy would increase over time!

The second Spitfire didn't reach anything near Mach 0.96. On board instruments were not made for that speed, and shown wild errors when nearing the speed of sound. Also the 980KM/h recorded by the Reggiane Re.2005 in July 1943 trials, by Cmdr. De Prato were not indicated by the on board instruments, but triangulated from the ground.

690mph jeez thats quick with a prop in front!

No matter how fast it rotated the propeller was a Wall of Steel that could not be overcome

It is possible that he did reach that hi Mach number, but the Pitot tube was designed for the aircrafts normal speed range. It might have been influenced by super sonic air flows. Chuck Yeager, the second person to go super sonic. The first one was George Welsh in a prototype F86 three days before.

My dad was in a Spitfire squadron as part of the ground support crew. As an enthusiastic participant, dad was convinced they could touch the speed of sound in a dive, they were the best plane ever built as far as he was concerned. Perhaps the pilots mistook the mini-booms from the propeller as an indication of speed?

We were walking in a field near the memorial arboretum when the bbmf spitfire flew low over us and round the arboretum, then the pilot circled us in the field as he’d seen us taking pictures as he passed, our own personal show, stunning plane and sound

Only the British would be so ''Honest', and overwhelmingly pleased with themselves, for being so.

gods looking at the image of Martindales spitfire, that thing looks almost unrecognisable as a spitfire... looks closer to a hurricane at that point

i doubt the highest speed in the spitfire as there was no propellor or frame damage. excellent video

Depends on how course you could set the pitch on the prop. The radiators on Spits are in the same location as P-47 dive brakes.😊

And this is why we have the Great in Great Britain...for all time

Didn't realise Declan Donnelly had a youtube channel.

Peter Spurdle dove his spitfire during a battle going maybe through the sound barrier and loosing a wing doing so.

I read somewhere that a propeller driven aircraft can never break the sound barrier because of the propeller.

T hx 4 sharing just ❤ the Supermarine Spitfire.

That was extremely interesting. As the Mosquito was the fastest propeller plane during the war I believe it would have been considered for these tests as well. But considering it has an all wooden airframe there was possibly some doubts as to its strength. The conversations about all this at the air ministry would have been very interesting.

Powell's ASI was broken as a result of the high speed dive, so it's very difficult to discern if the recorded airspeed of 690 mph was accurate. Some machine the Spitfire!

Thanks for a Great episode … I’m surprised that it wasn’t Eric Brown flying this Mission.. I thought he handled all the Mach Limit research ..

That was Sqn Ldr Tony Martindale attached to RAE Farnborough In a Spitfire MkXI He was testing transonic flight when his engine ran out of control He lost his spinner and he was flung all over the sky, passing out. When he came to he was at 40000ft no engine Wings Bent up and he then glided back 20 miles the Farnborough His Machmeter showed Mach 0.92

I think that speed with that Spitfire Mk. XIX was plausible, because that plane used a Griffon 61 engine, which meant a faster initial dive speed compared to the 1944 tests using a Spitfire PR Mk. XI with a Merlin 60 series engine.

Thanks for a great video!

The Northern tone sounds great for narration quite professionally presented subject. 👏👏👍

The Spitfire was not an especially durable aircraft. The P-47 not stripped down either for example, would go into compressibility in a frightening short period of time if the nose was put down as repeatedly recorded. But it never bent or broke. I don’t know how its possible to mention this and not mention both the P-47 and the P-38. If the special airspeed indicator was linked to air pressure as the standard A/S indicator is then its was not reliable in compressibility. And the Merlin had a reduction gear on the propellers to keep the propeller RPM down to avoid the tips and more of the prop going supersonic in normal flight. Its also dependent on temperature and altitude. AND once in compressibility its impossible to pull out until the aircraft got low enough that the air density increased to the point that the drag slowed the aircraft out of the compressibility range. It DID take a lot of guts to do this and a tip of the hat to the pilots. The reason Chuck Yeager was able to exceed the speed of sound and survive was the he and the engineers changed the horizontal stabilizer to a stabilator IE the entire airfoil moved like on a moder jest aircraft, even airliners. Without this mod super sonic flight was basically impossible. This gave the F86 in Korea an advantage over the conventionally tailed Mig15. Swept wings were not needed as shown by “Glamorous Glennis”, the F104the X-15 etc. But it DOES work better.

The Thunderbolt could dive with both the P-38 and the Spitfire, but few remember according to the P-51 Flight Manual the never exceed absolute top speed limit in a Mustang was 505 mph...

The highest mach number attained by a Tempest 5. 0.87 .

Very good history of the Closest sonic boom piston engine for the spitfire and can you do the next history of spitfire highest altitude

What an amazing video! The spitfire is such an amazing airplane!

I think that, on the balance of probabilities the Spit did reach a speed of Mach 0.96

One correction the Wright Brothers were not the first heavier than air powered flight. That had happened ten years prior by yet another French man Clermont Ader. It however had no control surfaces which the Wright flyer sort of did. They tried wing warping with some success but the idea was eventually abandoned.

You have to factor in that the speed is dependent on air density. I think that speed, or something very close it was in fact achieved in the far east.

good video that lad

I have a childhood memory of a film about these spitfire tests. In the film it was said that beyond the sound barrier the flight controls worked in reverse. The his would have been mid 60s, but I can't recall the title. Regarding the validity of speeds, a similar situation befell the GWR loco City of Truro in 1903. The guards timing log of the trains run show that it was certainly possible it surpassed 100mph, but it was discounted as an 'unofficial timing' !!

Didn't the American Bell X1 program basically steal all British data and have there project shut down.

Airspeed indicators use pitot tubes which may be affected by shock waves especially with propeller driven aircraft so who knows?

A lot of hot air here. Ignores the fact that the Spitfire was a poor diving aircraft. In fact German pilots used diving to break combat with Spits. I notice they spend a lot of time about the propeller, but no time on compressibility. Finally, all of these measurements on Indicated Air Speed depended on air pressure. Thing is, this results in wildly variable and unreliable measurements. No reliable, verifiable measurements exist for any of these claims. More than a few pilots even claimed to have broken the sound barrier during WW2 based on similar bogus measurements. ... Speaking of air pressure, Mach numbers are not absolute. They vary with altitude , air pressure, and air temperature. What may be Mach 0.89 at 30k or 40k is not nearly the same number as at 20k. These are some of the reasons post war speed records were based on performance over a closed course, using external measurements, not in a dive using unreliable IAS measurements.

I think the romours of ME262 breaking the sound barrier in a dive in WWII are much more beliveable after watching this.

Another side effect of these two speed test, which they fail to mention in the post flight analysis. Was the dark brown pungent hue left on the test pilots y-fronts ..

great video, very informative!

No prop plane of WWII vintage was "almost supersonic". NOT EVEN CLOSE. What tripe.

A staggering 469MPH! -The Northern Historian (yes I'm childish)

MPH is never use on military aircrafts: the did use only KNOTS (nautical miles per hour), or for all continental europe aircrafts, KM/h (kilometer per hour), and they did use same metric for altitudes

11:05 There was an instance where a Lockheed P-38 Lighting reached 780 mph in a dive, but its instruments weren't designed for accurate measurements.

I think I’d be more confused as to why the third spitfire didn’t take damage like the one before. That alone would make me question the reliability of the speed and possibly the story.

Yes

I assume that the quoted Mach # was adjusted for the altitude(s) the speed was measured at?

Yes I'll believe it, and its 112km/hr over so its not like a smidge. Thanks for the vid

Oh dear, people are going Spitfire Stupid again. This is the same old myth again. There's no "almost" supersonic when you're talking about M.0.92. The difference in drag between M. 0.92 and M.1.0 is phenomenal. As a general rule, drag increases exponentially with speed. So, to double the speed requires four times the amount of power. So if flying at 200 mph (to use old fashioned units) requires 500hp, 400mph will require 2,000hp. BUT! Close to the speed of sound is a phenomenon known as Drag Divergence Mach Number. At that speed, the previous rule no longer applies and the increase in drag becomes much, much greater. This is why it was known as "the sound barrier". There were those at the time who believed that flying at supersonic speed was impossible because they di not believe engines could be made powerful enough to do it (this was before WWII). Another factor is Critical Mach Number (MCrit). The Spitfire airframe varied a lot throughout its development and the only figure I have heard for this is 0.92 but I don't know what marque that was. Critical Mach Number is the speed at which the airflow becomes sonic at some point on the airframe. Just for the record, 0.92 is very high fr a propeller-driven aircraft and I'm starting to wonder if they included the propeller. Funny things happen at MCrit. Shock waves for for a start and that creates a high pressure zone ahead and a low pressure zone behind. They can cause strange phenomena and can be very dangerous. There is a photograph in William Green's "Warplanes of the Third Reich" which shows a Me-163 tail which was shredded when it exceeded its MCrit. This is why pilots were advised to avoid flirting with these sorts of speeds. In the photograph of Tony Martindale, sharp-eyed viewers will note the man third from the left in the RN/FAA uniform. That, of course, is Eric "Winkle" Brown, who was as much a part of the diving program as anyone. Brown flew every marque of Spitfire. In his book "Wings of the Navy", Brown describes flying the Seafire and includes its dive performance. He notes that he had flown a lot of dive testing, including to the aircraft's MCrit, by which time, it was - in his words - totally out of control. The most important thing to take away from this is that the airspeed measurement instruments of that period were not capable of measuring high mach numbers and TAS conversions don't work. This is because air piles up in the pitot head and creates shockwaves which cause incorrect readings. There have been hundreds of USAAF P-47 pilots who claim they have flown supersonic in a dive, simply because of TAS conversions. Did a late model Spitfire fly at the speed of sound in the 1950s? No way. Not a chance. Not in a month of Sundays. The TAS conversion of 690mph is worse than useless at high Mach. You might as well be towing a log for all the use it was.

Did anyone else find the temperature drop at 11:54 ?

I think this is a great little video 👉🇬🇧👈👉💎👈

Heard somwhere Powles could see the telltale clouding on the wing leading edge during his dive in the XIX. Can someone verify this? If it is true, it might indicate that indeed he was close.