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P-51 vs. 109 Drag, The Truth!
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- Опубликовано: 22 окт 2019
- The P-51 does have low drag, but why? Is it really because it has a laminar flow wing and a thrust producing radiator. Let's take a look!
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Sources:
Quest for Performance, I sometimes refer to this book as Evolution of Design:
ntrs.nasa.gov/...
Wind and Beyond:
Part 1 history.nasa.g...
Part 2 history.nasa.g...
Part 3 history.nasa.g...
Part 4 history.nasa.g...
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Note:Regarding the comment at about 20:50, I'm not 100% clear on what number I should be using in the calculator, 1.0, or 1.171. On page 4 of Quest For Performance it mentions both numbers, and I'm not sure which one they used to come up with that 3.57 number. In either case, it won't effect the relationship of 109 drag to the P-51 so I'm not worried about it at this point, but I'll have to sort this out in the future.
Thank you for addressing this. I've been an aerospace engineer for over 41 yrs, and routinely hear the myth of the Pony's magical laminar flow wing. Yes the 45-100 is an impressive low-drag airfoil, but the chances of a production wing (built with 1940's manufacturing technology to tolerances achievable in 1940) achieving significant laminar flow (the boundary layer being only about .02" thick) is a pipe dream. The 51's forte was it's low parasitic drag, not laminar flow.
Another fact that will undoubtedly upset many fan boys is that the 51 was not exceptionally maneuverable (the roll rate being somewhat dismal). It WAS very fast, and great for Boom & Zoom tactics. But in a turn fight, planes like the 109 (especially the agile 109F) could and did give the 51's fits when they met on an equal footing (equal numbers, same speed, altitude, etc.) Unfortunately this seldom happened, the Mustangs routinely enjoying the advantage of numbers, initial speed, and initial altitude.
Thanks Bolt.
Pilot expertise in a turning fight was more critical than usual with the 109. In expert hands it was formidable, but its instability near its limits shrank its envelope considerably for most pilots, especially towards the end of the war. That's illustrated by accounts of flights of 109s that were mostly trivial opposition but with one or two hotshots that presented real problems.
I know ur comment is over a year old but buddy it is still "Fresh". Pointing this information out to aircraft enthusiast is about like convincing a liberal to accept facts. The P-51gained fame for 2 reasons. It could do what he spitfire did but with better mileage(Bomber crews really really like this as such have talked it up.) And the fighter tactics developed for stressed skin monoplanes (New and Hot stuff at the time) were based on the belief that "Planes of today are way to fast and therefore the days of dogfighting are over", that and the dangers of turn fighting with the Zero. So boom and zoom was developed and taught as the main basis for attack. But even with all that if the guy kickin the pedals isn't any good it's all a mute point.
@@warrenchambers4819 Thanks Warren. I'll also point out that another key to the Pony's legendary speed was the quality of the fuel available to the Allies. While the Germans were making do with 87-89 octane fuel (when they could actually get fuel), the Allies had access to 130, and even 150 octane gas. This allowed them to boost their engines to absolutely ridiculous levels (for the period). Not a good thing for the longevity of the plugs and exhaust valves, but a definite plus if the pilot found himself in a bad spot and needed to get the Hell outa Dodge.
@@BoltUpright190 I'm a autoTech(Grease monkey) and have been for over 30yrs so I can really appreciate your point. And your right it sure seemed to be our theory back then. A good example is when one visits the museum at Wright Patterson. The set up there really drives the point home to the visitors. They start you out going thru the axis aircraft of which they really have an outstanding collection and some really rare birds. But once you've seen a real Zero, the 109 and Fw-190 you round the corner to a monster. Your entire field of vision is filled with P-47, which is as big a twin engine bomber and it's only a single seat fighter plane!???? Dam. It dawns on one those engineers back then said " We got only 3 requirements. #1 Horse power and lots of it. #2 Guns, Guns, Guns and yes More guns! #3 Gas. More Gas. Lots more Gas (We've got plenty O gas keep it coming) Drop tanks for yup you guess it mo Gas!" I can just hear someone from way in the back of the room sayin "But sir the fuel mileage? " only to hear "Dam son your right and good idea!!! We'll add some more GAS!" Hahahahahahaha
Propeller design can have a huge (at times ignored) impact on performance.
I would love a video focusing solely on propellers' efficiency differences.
Thank you ever so much. This channel never disappoints.
Dude, if this was a class at a university I'd take it in a heartbeat.
I really appreciate your unbiased approach on these topics. On my videos, people get into heated discussions without any data to back it up all the time. Most of these discussions are just opinions fueled by natinal pride of the country they are from. So your videos really are a refreshing contrast to all this fighting about things no one has really looked into. Also, if you need some footage for future videos, you can use mine, just give some credit et the end of the video. Looking forward to your next lecture. Thanks a lot for these!
Thanks Paddy, I will probably take you up on the footage offer at some point, and of course I'll credit you.
Mark Felton is of similar nature albeit a related but different subject.
Very much enjoyed that, thanks Greg!
Yep, he does an excellent job of highlighting the technical issues of developing aircraft.
I was just now wondering if you knew this channel...
Nice to see you here!
The value you add to this "community" is actually insane!
I totally concur.
Ja!
These warbird technical videos are fascinating; keep them coming please!
You should INCLUDE A SUMMARY for the every man!
(1) The P-51 has a high speed wing; the Bf109 had a lower speed wing.
(2) At sea level, the P-51 has lower drag at speeds over 240 mph; below that speed the bf109 is less draggy.
(3) However, if you fly really high and really fast the Bf109 can actually have lower drag!
(4) This is because when air gets thinner at high altitudes, a low speed wing which produces more lift at lower dynamic pressures is able to operate at a lower incidence to the airflow.
(5) However, in practice, the Bf109 is never faster because it is draggier at high speeds at low altitudes and it losses a lot of engine power at high altitudes due to its supercharger design.
(6) None of these have anything to do with laminar flow or the lack thereof; the P-51 simply as a wing optimized for higher speeds.
Dwight gets it. Well done Dwight.
Greg, your YT vids are so informative, I watch them more than once!!!!
Yeah there's more information here than I can soak up in one pass.
I watch them several times, first at regular speed, second at a faster speed but then slow it down for the information heavy parts...depending on available time.
@@nzsaltflatsracer8054 i agree, suprisingly great content.
Would love to see a similar comparison between the F6F and the F8F. Same manufacturer and virtually identical engine for both, yet the Bearcat was substantially smaller, lighter, faster, more nimble, and a better climber.
Greg had a great video on the Bearcat. Apparently climb rate for carrier defense was the main parameter and could do that job. But taking away fuel and guns makes the whole concept seem too niche to be a real advance in technology. IMO
The Hellcat was the highest-scoring fighter plane of the war in the Pacific. It downed more enemy airplanes than any other of the planes in the Pacific theater. I think that is one reason Dodge named their car after it. What other car from America has achieved such overwhelming dominance over Japanese machines?
@@exploranator the corsair out performed it
🎉
I was recommended this video a few days ago and since then, I've been working my way through all of your videos! I'm really blown away by your channel! This is some of the most in-depth content I have ever seen on RUclips!
Thanks Evan. I'm glad you like the channel.
My Dad flew Mustang MK111’s for the RAF. The photo was called a MK1 in the RAF, Had an Allison engine. They used to just fly in training areas. I know he spent a lot of time in Scotland but they used to practise with Spits & Tempests including dives, zooms climb speed etc. There is data released on the net of Test pilot reports that match exactly what Dad said about these comparisons. Shaking due to compression became a problem with the plane shaking itself to bits in an emergency dive. He said you couldn’t read the instrument panel had no idea or cared how fast he was going.
Beagle76 Tell him thanks, I’m glad we have hormone replacement and drag queen story hour, it would be horrible to be speaking German.
@@BikingVikingHH You and I know it isn't that nuanced. Well, you might not, but as a historian of 20th century politics, I could tell you the reality is more of a slave labour of everyone deemed undesirable, and that the destruction of fascism and other similar far-right nationalist movements during the 20th century has made the world a better place for everyone regardless of what your outdated views might be (being assigned the wrong sex at birth is a very real scientific phenomenon according to one of my friends who is a geneticist).
I'm grateful to Beagle's father for his service to our country. My great grandad wasn't in the 'raf but was on board HMS Belfast in the 'B' Turret we got his arctic star recently and I'm proud of his service, especially knowing the tale of the sinking of the Scharnhorst, and the harsh conditions on those arctic circle convoys. one of my other great grandads was in the REME, another in the RTR and the final one was an ARP warden in East London, although unfortunately I don't know as much about their service.
@@Reddsoldier you're wasting your time if you're trying to talk some sense into that deluded fuckwit. you'd have a better time trying to get a coherent response from a glass of stagnant water.
@@halowraith1 Yes, because it's quite certain that those brave allied veterans would've been thrilled with the idea of having their progeny become a minority demographic in their countries of birth via mass immigration. You and I both know that if they had been able to see into the future they would have gladly sided with ol' uncle Adolf.
@@jaromeunrooski6963 you go and get the opinion of those veterans then, and show them to me.
Excellent Video! There are little words to describe, how well it feels to have an engineer's explanation on a given topic!Hats down!
The most erudite channel on youtube. Thanks again for working through the math, and giving us more than data from video games. Original sources? I wish everyone was so thorough.
I agree 100% And I don't even know what "erudite" means.
Presenting the NACA reports is off the geek scale and it doesn’t get any better than that.
Thanks for the Do. X reference! A video on the Do. 335 would still be appreciated.
What a wonderful piece of work. I have watched this many times because I have frequently wondered how the P 51 performed so well. After watching your work on the P 47 it is obvious how it got it’s great performance. Now I have a better grasp on the Mustang. Thanks for the amazing work. I sincerely appreciate what you do!
Thanks Carl.
In his book "P-51Mustang: Development of the Long-Range Escort Fighter" Paul A. Ludwig notes that the Rolls-Royce test pilot Ronald Harker, who flew a Mustang I at Duxford in April 1942, realised that even though the Mustang weighed more than the Spitfire, it used less power to fly faster. Ludwig notes that after the war ended, Richard Whitcomb at the NACA discovered his area rule principle which states that an inward-curving portion of the fuselage above the wing joint will prevent the air streaming around the fuselage colliding with air passing over the wing, causing turbulence and drag. The Mustang's fuselage had flat sides while those of the P-38, P-47 and Spitfire were fashionably rotund. The Mustang also had the highest Critical Mach Number of any piston-engined aircraft of the war and the lowest drag.
Great point.
This is very interesting because I remember reading a quote from a Japanese pilot saying that he had no trouble fighting the P-51A in China or Burma and that they did not better than the P-40 he would face but when he returns to Japan and faced the P-51D it was a real dangerous plane. This is from the Osprey Ki-43 aces book if I am correct
Love your stuff. Always wondered about the “laminar flow” wing. You make this stuff understandable.
I love the depth you go into with your videos. There are a lot of very good aircraft video producers out there, but you really dig into the details and do a Myth Busters level of research and demonstration.
Your vids really speak to my inner geek and I appreciate them. Thank you for the hours of entertainment and education!
Thanks, I won't ever say 'laminar flow wing' in relation to the P51 ever again. I appreciate your research and calculations and making it available in an easily understandable form.
For years I thought it had laminar flow as well, but NASA says no. Sometimes we have to change our minds when strong evidence shows up.
@@GregsAirplanesandAutomobiles If I interpret the data you show correctly, though, the wing potentially had laminar flow over 40% of the chord, under ideal circumstances, right? Just not in actual use.
That's exactly right. A perfect wing in a wind tunnel could do it an actual airplane off the assembly line, really couldn't.
Greg,
I like your common sense/scientific approach to all of your comparisons (scientists just use facts & figures & data)you always use the same approach rather than saying “well I think it’s ?” Then common sense just speaks for itself and goes a long way in comparing different things. Thanks
Always looking forward to your next piece.
Discussions on laminar flow have often sounded like the, "but this has electrolytes" trope from the docucomedy movie "Idiocracy." Thanks for the clarity. Keep up the good work!
Just an aside: For all the Bf 109G series' faults, it shot down more aircraft and made more aces than any other type in history, especially during the less "sexy" middle period of the war (1942 - 43) in North Africa/Mediterranean and the Eastern Front.
A lot of those kills came at a time when German had air supremacy over most of Europe and Soviet aircraft and pilots in shambles though. Still require skills on the pilots part but its hard to quantify how much of that was skill and technical superiority vs other wartime conditions purely based on K/D ratio.
@@neurofiedyamato8763
North africa wasn't a theater where germans got air superiority.
Not even in Russia. In 1942 germans got no air superiority anywhere. Maybe some temporary local superiority. But after Bob things started to become quite even. On 1943 they were on the lower side everywhere.
Germany had local air supremacy in the Eastern front up until around 1943. And that's all you need to rack up kills. The luftwaffe couldn't be "everywhere" but while they were there, they got plenty of kills. Germany had air superiority on the opening stages of Kursk for example. Germany racked up plenty of kills but they withdrew and lost air superiority. That didn't mean they lost it in direct confrontation.
Air supremacy =/= kills and kills =/= equipment or skill superiority either.
For a good overview of how things actually happened, multiple factors have to be considered, not just 'kills' or 'air control.' You need multiple factors to corroborate first.
Also I said most of Europe. North Africa isn't Europe. I said Germany had air supremacy over Europe which they did in Poland, France, Norway and whatnot. Pilots most definitely racked up a lot of kills during those stages. Early USSR also did not have air supremacy, as I said above, Germany dominated wherever they are even if they did not have total control. Need I not mention how Germany could supply encircled troops purely by air in the early stages against the USSR?
@@neurofiedyamato8763 Actually, kills in France, and before were not that much.
The battle was too short to rise up on kill claims. Same thing happened in poland and eastern europe.
But north africa involved the planes in question at almost the same time, with the afrika korps luftwaffe being in far lesser numbers than their commonwealth opponents.
When things were one to one, the germans got the better part. Later they were decimated a far numerous foe.
Same thing happened in the channell.
You can check Priller score. 101 voctories all in the western front.
Also british pilots didn't do tours as far as I know the same way as american pilots did. They only started limiting flight hours on 1942.
Priller did 307 combat missions with 101 kills, that also includes damaging bombers as kills, and maybe a full vier motoren who may be counted as four.
But one of the better english aces, got 37 kills onnmore than 700 tours, and mainly on the same places. At a time where forces were pretty matched.
To quote Patrick Shea Simonds, from the book "Spitfire" by Alfred Price, when talking about the laminar flow wing on the Spiteful,
"The idea of the laminar flow wing was very fashionable during the mid-war period as a means of achieving low drag at high speeds. But when it was being tested on the Spiteful, the new wing did not give much improvement in performance over the late type Spitfires. The theory of the laminar flow was all right, but only so long as the wing profile had been manufactured to very fine tolerances and the whole thing was kept free of dirt or minor dents. It needed only a squashed mosquito on the leading edge, and the airflow over that part of the wing went for a Burton!"
Yup, that agrees 100% with the data I put up in the video.
@@GregsAirplanesandAutomobiles yeah mate bang on
The US Laminar flow tech was developed by Eastman Jacobs of the NACA. Jacobs understood that the wing he designed wasn’t laminar flow in practice. But Jacobs knew that the wing also had much higher Mach limit, about 10%. It was this lower shock drag that gave the P51 better drag since 440mph is Mach 0.66. Jacobs was working on “Jacke’s Jeep” to break the speed of sound using a motor jet and these wings.
I really enjoyed this presentation! I was lucky enough to have had a father-in-law who was an Aeronautical Engineer (Graduate of UVSB) who later in his life designed some of the most remarkable Slope Racing Gliders (earlier in his life his he and his brother won a “Best of Show” Award in the “Ultralight” Category at Oshkosh in the late 70’s) ever to fly off the bluffs at the Torrey Pines Pines Glider Port and other similar glider sights. He also designed numerous remarkable “Hand Launch” Thermal Soaring Aircraft as well. He taught me to fly his RC aircraft but before I ever got to touch the “stick” I received a crash education in NACA Slow Speed Air Foils (one of his favorites was the NACA 7037), Reynolds Numbers, “Boundary Layer” principles, “Lift Over Drag”, Roll Rates, High/Low Speed Stall Characteristics, and so forth however the thing that mattered the the most to him on his aircraft designs was “Parasitic Drag”. Of course since he didn’t have to worry about landing gear, canon/machine mounts, or supercharger ducts his aircraft were ultra clean with parasite numbers in the “nth” percentile (of course it also mattered that they were in general small as well in the 60” to 2-Meter Wing Span class) compared to the P-51 or Bf-109. I of course love “War Birds” like the “109” but he would scoff and say “Uhgggg way too much parasitic drag but I did like the “F” model it was the cleanest”. He “slipped the surly bonds of this earth” unexpectedly in April 2015 but your videos remind me of listening to him talk as he was just an encyclopedia of interesting “aeronautical, aviation, & aircraft information”. It was his one true passion in life.
Droo Phus Thanks for sharing that. That's a nice story of your father in law. You honor his memory well.
@@smportis My pleasure. Thank you!
It's great to see a WWII fighter video that really gets into the numbers. We need videos that also do that not just aerodynamically and mechanically, but also for combat performance in terms of damage inflicted on the enemy per dollar. For example, the kill to loss ratio of the Mustang in the European theater was 3.6 at a cost per plane of $51k (includes ground kills and Mustang losses from all sources). The kill to loss ratio of the P-38 was 1.4 at a cost of $120k per plane. The Mustang was 2.5x better per plane and 6x better per dollar, and more than 10x better per dollar if you take into account that it cut bomber losses by more than half. If operations research applied to combat performance was better published we would not see videos ridiculously claiming that the P-38 was the best fighter of the war. For strategic leaders and aircraft definers the goal is to define and purchase the best air force for the available budget. It is light fighters like the Mustang and Bf 109, and in modern jets light fighters like the F-16 and JAS 39 Gripen, that deliver the most losses on the enemy per dollar (and usually per plane also due to superior surprise and maneuverability). For some reason this lesson learned the hard way in combat is consistently forgotten in peace time. My guess as to why is that if an air force says it will buy a certain number of fighters, the plane manufacturers push big expensive twin engine fighters (Bf 110, Beaufighter, P-38, F-4, F-15, F-22, Eurofighter Typhoon, Rafale) because planes are sold by the pound, so the big fighters generate twice the profit.
Fascinating and highly edifying. I must say, Greg, I have learned more about "fighter science" from your videos than from all of my reading. This is not the first of your videos I have linked around to my friends and fellow armchair historians. Thanks for posting.
Thanks William.
My dad flew P51Ds in the war against the Japanese. He used to say the P51 had the Laminar flow wing design when I was 5 -10 years old in the 1970s. Being that young I had no idea what that meant but it seemed to indicate to me that it had a special design in the shape of the wings which gave it a very special advantage.
As always, top notch Cap'n! I genuinely appreciate the time you put in to the data gathering and analysis. It certainly shows in these presentations.
You are absolutely barmy. I don't know how someone can put so much info into strangers lives without something to gain.From the bottom of my heart THANK YOU.
The dornier flying boat really gave me a good chuckle, thanks for finding a way to mention it. Great video as always!
The fascination with detail pays off. True knowledge emerges; the kind that stays with you. Deep waters for me, but spellbinding as you avoid the generalities and focus on applicable specifics. I do not know anywhere else this infotainment is shared. Cannot miss a vid. Great work!!
Thanks for WW2 planes breakdown. Amazing what designers did without computers. My dad worked on F3F as a kid & finished his career working on F117
Making the technical understandable to non-engineers once again. Well done.
about damn time you did another 109 video - looking forward.
You're not wrong! This video is way overdue.
My understanding has always been a "laminar flow" wing" refers to one that had a different cross section, where the thickest part of the wing was closer to the mid point of the chord than the typical wing of the time, where the thickest point was not far from the leading edge.
A laminar wing is one that maintains a laminar boundary layer significantly behind the leading edge. Its drag polar shows a distinct "bucket" at some range of lift coefficients, where this occurs.
A negative pressure gradient is needed to achieve this, which is indeed done by having the thickest part closer to the mid chord. This however is not enough to make it a laminar wing. The camber must be shaped to reduce thickening of the boundary layer, and the surface must be very smooth.
The negative pressure gradient that is achieved in this way is not very strong, so these airfoils are very sensitive to tolerances and surface roughness.
Test pilot "Corky" Meyer did a lot of flying for developing laminar flow wings, as did the British test pilot captain Eric Brown. They described inflight tests with aircraft equipped with adhesive wing surfaces flying through clouds of material released by other planes. This was to determine laminar flow characteristics of wings before, as mentioned in this video, "bugs got stuck to the wing and before people started wallking on them". Results were disapointing. I will have to look this up in back issues of Air International.
Terrific video, Greg - I am one of those people who (mistakenly as it turns out) boasted of the 51's advantage due to it's laminar flow wing - I appreciate your detailed explanation and evaluations. Thanks, JG
Dont feel bad.everyone from that era was told the same bullshit on the laminar flow wings .i can still remembet my fathet telling me of americas air suppremacy due to special shaped wings on the mustang
Fascinating- reminds me of (I think it was) Will Rogers- "its not what we don't know that matters- its what we know that actually isn't true" paraphrased
I enjoy your descriptions, especially with the great vintage materials you use for illustrations.
You hit the point that always intrigued me.
I got to watch Hoover at many airshows. The mustang seems to take FOREVER to accelerate after being slowed down in the air. You explained it when discussing the drag at low speed .
The summation of this is its really up to the pilots skill, and ability to have situational awareness. As well as knowledge of his opponents aircrafts capabilities that was the deciding factor in a head to head matchup.
Awesome subject! Thin wing = less drag and lift. Laminar airflow was never achieved on the Mustang, however that radiator scoop was a breakthrough. What a difference having a retractable tail wheel
Plus the tailwheel is enclosed once retracted.
The Meredith Effect [ radiator scoop] was known before the P51 was even thought of.
I believe it was attempted though, it’s just that Manufacturing wasn’t up to that level of precision needed for it to work
@@spindash64 True. I still see articles that state the wing was laminar. Oddly, the bubble canopy had more drag than the C model
Jim Wahl
Not as large of a difference as is claimed either though: most of the performance differences are due to increased weight (addition of tail fillet on later models, extra guns), and a different engine geared for lower alts (the -7 thus gave a lower TAS max, but better power in a larger band)
It would be fine to see in future a vid about the P-38
Love that fighter.
You mentioned that the P-51H was basically a new plane. It’d be interesting to take a look at how different it was. I’m also curious about how both the Martin Baker MB 5 and the CAC Kangaroo designs looked very similar in basic layout to the H Mustang
I enjoyed your presentation. It brought back a lot of the concepts I learned in my aerodynamics class for my BS in aeronautics!
I have to recap the drag chapter in order to get all the info from this excellent analysis.
Surprising findings anyway!
Thanks.
I’m an airshow operational responsibel CO. Also certified pilot for low level aerobatics and some vintage airplanes. The information and numbers here correspond very well with what Cliff Spinks ( UK Air Marshall) said about the Me 109 (Buchon Merlin engine) to me before an airshow doing a mock dogfight with P-51 « Big Beautiful Doll». At low altitude Cliff turned inside the Mustang and shot it down to everybodys surprice. The Mustang may rule at high altitude, but definitively not at low due to the Mustang higher induced drag in turns.
You low level aerobatic folks are impressive. I have done aerobatics, but always with a lot of room below me.
@@GregsAirplanesandAutomobiles Well, room below has increased with the years also for me. Certified for airshow aerobatics in my 20ies and 30ies to 50 ft straight in level manouvers and 200ft for turning manouvers - there are no margins for error. The world is not perfect so what happens if somethings breaks or pilot error. Not sustainable. So today in my 50ies I do areobatics mostly above 2000 ft and with the docile Bucker Jungman. See my channel, look at the video about aerobatics with the Bucker Jungman Neil Williams style. It is going back to the roots and more healthy margins. The Lomcevac airshow at low altitude ended with this flight, see "Opening Airshow at Hvittingfoss 31/8 2013". Nothing went wrong there. However, last flight for this homemade airplane after 22 years service. Airplane is now in museum, I gave it away as a gift to our national aero museum in Bodø. Hangs in the roof. Mostly because of some other other odd stuff we did with it. Docking wingsuit parachute jumpers to the wingtips of it 22 times in 2012. Special designed wings and winglets for that. Fully legally and certified by Norwegian CAA. Not before the Draco in the US 7 years later it was done again. That much said. I really enjoy Your videos and while driving car for my hangglider adventures I always put youtube on the speaker and listen to what You have to say mostly without any visual. The wider understanding of compressors, superchargers and turbos I must admit that even flying some of this airplanes in the past the videos have contributed to a much better understanding of how this airplanes were matched up against each other and why. Today we (or my airshow fellow pilots that is) fly them on 100 octane fuel and lower boost for several reasons. In same museum as my old airplane hangs, there is a Me109F under restauration on the back room. Studying the hydrostatic controlled side mounted supercharger on the Daimler Benz and understanding how the bad fuel the germans had available contributed to high displacement engines and lower boost. Also a FW190 at the museum and the displacement on the BMW is even bigger. Looking at the lower displacement Merlins but very good performance over the altitude range we run Your videos to understand why. On my wish list for another video from You is a bit about german propeller wartime technology. US planes utilized quite big diameter and high surface area props. Sometimes with squered tips which puts high demand on pitch control precision. Probably for high altitude performance? Looking at german fighters, especially in the later stages of war, the props are not that big diameter and blade shapes are more tapered. Pointed tips. Most dominant on Me109 G and FW190 Dora models. Why is that?
I love your work and the effort you put into defining these obscure coefficients!
Excellent discussion including the effect of size (so surface area to volume ratio) on the true performance and utility of different designs (which is after all why the British ordered Mustangs to add to their airfleet)
Thanks for the clarification of the term "free"--much needed!
Another fantastic video, making me realize larger concepts of "drag" per altitude, thanks Greg. You got me wondering about induced drag for the different wings under G loads now.
Thanks Eric, I look at this under load in some other videos, I think the 262/P-80 one, but I'm not sure.
Does this mean we will get a super critical air foil vid? I Love learning from your channel!!!
I've learned a lot about some of my favorite aircraft on this channel!
Another top notch examination/explanation of flight characteristics.
This channel is pure gold! Thank you for the "free" book tips.
Thanks, you're welcome.
Regarding the P-51`s dog-house. One thing that speaks against the idea of producing more thrust than drag is the fact that some P-51 reno racers removed it, flattened the bottom of the plane and installed some kind of boil off cooling. Now, this doesn`t mean that the dog-house produced more drag than thrust, but still, did they gain anything by removing it? I wonder if there is any information on that. I`m referring to Galopping Ghost and some other Mustangs.
That's a good point, I hadn't thought of it. Clearly if it added thrust you wouldn't ever get rid of it.
I mean, it probably did produce more drag than thrust, the engine can't put out THAT much extra heat. But the original design probably offset some of the drag by pushing the hot air out the back. I think the excellent fit and finish, and the streamlined scoop probably cut down the drag more than any additional thrust, though.
I imagine the boil-off cooling system they use is lighter than the radiator and aftercooler thus not needing the scoop.
@@ginacalabrese3869 Probably, but also, boil off cooling extremely limits the your flight time. And you have to carry all the coolant.
@@PaddyPatrone Of course, but the racers know how long the races are and can plan accordingly. Galloping Ghost definitely had a boil-off system (mentioned in NTSB report) and I believe some of the remaining racers do too.
Love your videos, I've come late to. My Father was a draftsman/engineer at North American during the mid-war development of the later models of the P-51 (Started at Douglas on the DC3 right after school), and was involved in the conversion of the jet engine B-45 to a flying test bed NA made for GE and then for Westinghouse, where several the engines for the Century Series fighters were developed. Probably the last bomber developed before the German data on swept wings led to the B-47 and all later. He then accompanied the second test bed to Westinghouse, and ran their program. Later becoming an Atlas missile test conductor with 6 'nominal' flights. I've been following these aircraft all my life. Your videos rank at the top of WWII airplane history I've seen or read.
Much as I love discovering these series of videos, finally a section I feel could be improved. Contrary to so many explanations, the section on drag coefficient seems labored, and never quite gets to the core. This in a series where complicated math and Physics are usually presented excellently at several levels, interested beginner, generally educated non-aerodynamicist, and fussy math student. A most impressive accomplishment. My catch-as-catch-can education means I'm all three at various points.
The coefficient of drag is simply a coefficient, or multiplier. Any size shape of the same geometry/coefficient will have the same relative drag, surface drag effects that change with scale ignored. Multiply the frontal area by the drag coefficient and you get form parasite drag as a quantity which multiplies by the square of airspeed to get a drag figure. Assuming speeds below compressibility/mach effects. Smaller frontal area, same coefficient (Shape), less drag, in almost direct proportion. In this case, at many speeds and altitudes, the smaller frontal area airplane (Me-109) with a higher coefficient still has less drag. That the parasite drag curves cross shows the complication of 'simple' relationships in real life.
If this video production is ever revisited, and for all future production, the lack of labels for some graph quantities and number conventions is both confusing and frustrating for me. Meaning I'm spending more time pausing the video and trying to understand graphs, not always successfully. Example: the several graphs starting about 23:00 seem to have the left vertical (Y-axis?) as altitude. I'm assuming meters? Feet are used in the narrative?? Both quantity and numerical convention (Metric, English, SAE) deserve notation, which I'm sure isn't always direct to add seamlessly to material found in period sources. When possible both meters, for the rest of the world, and feet, given the numerical experience of American audiences. I'd list ideas for future videos I'd love to see, but I expect you already have more than a lifetime on your to do list now. Hope you are enjoying these as much as we are.
Hi Bill, First of all, are you a fellow grappler? I ask because few people other than wrestlers would use the phrase "catch-as-catch-can". On the the subject...The graph you mentioned shows drag in pounds on the vertical scale and speed in mph on the horizontal. That particular graph is one I did over, as it was based on what I later determined to be bad information on the 109F's best glide speed. The corrected version is in my P-47 part 5 video. The entire world now uses feet for altitude in aviation except red China (which excludes Hong Kong airspace, they use feet). This became standard about 8 years ago. Your points about the coefficient of drag and the explanation is all good. When making videos it's always tough to decide just what to include or exclude, and how much detail I need on any given item. Video length is always an issue.
@@GregsAirplanesandAutomobiles Not a wrestler, but a few friends were. I was just a skinny kid who read too much. Which led to a love of well turned phrases. Which I'm happy to see dropped in your narratives here and there.
I'll go back and look at the graph for comprehension. The discussion mentioned altitude while the graph was on the screen and I couldn't see the connection.
Loved getting to understand the P-47 better. A much more complicated and sophisticated plane than I'd understood. The memoirs of a post-Normandy ground support P-47 pilot were unsettling. He referred to his unit as hired killers. At a low salary. They went out and killed German high school kids all day, making return trips with new loads of munitions 5 or 6 sorties a day. Nothing he enjoyed, but it seemed necessary??
Probably short on material compared to the more visible US warplanes, but a video on the P-39 might find info few suspect. An uncle by marriage told me he was the only graduate of his advanced fighter class who survived the transition to the Airacobra. The rest were killed learning the airplane, or transferred to the infantry attempting to survive. His critique was he liked it more than any of the other AAF WW II planes he flew, which was everything with a single engine and guns. P-51s may have been the meat of his missions. Withdrawn from combat to become a check pilot on injured pilots returning to combat, he had flown over 250 sorties during the air war over Europe.
The issue with the P-39 he said was the aft CG, leading to an unrecoverable flat spin once entered. And extremely difficult to bail out of in that event. So he never let it enter a spin. The aft CG also made it uniquely maneuverable, to his judgement. His other comment was that his model was unflyable in combat. The two machine guns in the cowl dumped gunsmoke into the cabin, and the pilot lost all visibility about 3 shots into a burst. I assume this was fixed on the models the Russians loved.
Like every other veteran of air combat I met through my father (My only male relative of his generation who didn't fly in one service or another, if you don't count his, and Mom's, flying wartime CAP patrols over the West Coast), not adverse to discussing the machinery, but never said a word about the actual combat. Dad's oldest brother did say he'd been on IIRC, the second Polesti raid, but no more. He survived a full tour as crew chief in Liberators, the only non-pilot in the family. I never figured out if their reluctance was refusal to revisit the horrors of combat and lost friends, or an estimation of what honest relating might do to a kid.
A lot of WW2 stuff is very uncomfortable. The kill anything that moves philosophy was one of them. I don't have good answer for that, war is hell.
@@billtaylor3499 Nice post, Bill, thank you. I recall the Aanenson documentary when it aired, and similar themes came out. War is so ugly. I wish we didn't find fascination in its machines.
Greg I love how you dont stick with a favourite and jus tspeak truth and facts! Very interesting videos!
Thanks, all these planes are my favorites. If I absolutely had to pick one, it would probably be the 190, not because I think it's the best, but I just like it for some reason. Then again, ask me tomorrow and it might be the Corsair.
@@GregsAirplanesandAutomobiles Haha! Two Great planes!
Pretty cool video. One story on why North American Aviation was engaged by the U.K. was the quality, fit and finish of previous production aircraft
F was favorite of many German aces in thier memoirs
Farmer Ted one of my favorites too!
G and K basically tried to put an 1945 engine in a 1942 plane, so naturally it wasn’t gonna fly as smooth
that is why..Bf-109 F für "favorit"
eric Hartmann exclusively used the Bf109F
@focke wulf Not according to his book He always favoured the Bf109
When comparing radiator drag the P-39 Airacobra is also an interesting case - it had the same Allison engine as early P51s yet the radiator intakes are just two tiny holes in the wings' leading edge, near the roots. With a clever internal expansion and venting system, this eliminated the need for underslung radiators altogether. I read somewhere that cooling with this system was "more than adequate" and often wondered why it was not used on other liquid-cooled fighters of the day.
Bart Duff because rhe P39 was not as efficient as the others
The hard math behind the facts. Pretty deep but with plenty of explanation to drag some of us along. I did enjoy the ‘circular’ comment. Using sources that use other sources with no clear data to backcheck is a lazy and corrupt methodology. Kudos
An interesting well considered video.
Have you seen the Rolls Royce Heritage book “Rolls Royce and the Mustang”. They say the first flying Mustang X took to the air just 6 weeks after they received the planes for conversion. The Merlin 61 had a much bigger two stage supercharger that the Allison.
The X had an engine cowling with a huge chin intake for the charge air cooler. Yet it was just 4 mph slower than the far neater production model. Check out a Mustang X nose with a Lancaster bomber engine nacelle.
RR wanted separate radiators (side by side) and separate glycol lines for engine and charge air coolers. Logic being temperatures could be optimised and battle damage gave some change the engine circuit be undamaged. Production planes had just the one cooling system.
Lots of people make the same cD mistake in the automotive world. They think it means total drag and don't realize you have to factor frontal area.
Excellent point.
Yep, but i have to say, that it is a handy number. It does tells you how aerodynamic a design is independent of it's size.
This is perfect for things like wind tunnel tests were you have to use smaller models, to get an idea for the quality of your design.
Of course, in the automotive world, a low Cw number also is a good way of advertising your design ;D.
Another of your excellent videos. The data that you show is commendable.
I have a fascination with aircraft and enjoy the stories and experiences of the pilots that fly them. I enjoy the flight simulators that give you a feel for the real thing.
Another fantastically informative video as always Greg. I must admit I never put much stock in the laminar flow everyone harps about, the wing was low drag for sure but the rest of the aircraft was simply superbly slick. Especially with American manufacturing tolerances.
Although I never knew that the Meridith effect was not all that it was cracked to be.
Great stuff as I said, I look forward to the next one.
The Meredith Effect was quite good on the Spitfire
I believe it was Ludwig Prandtl, German aerodynamicist, who told the German Luftwaffe that he believed it would be nearly impossible for the Allies to maintain the P-51's fuselage in as clean a condition as would be necessary to maintain the low parasitic drag laminar flow condition it was designed to achieve. This was probably a conjecture on the realistic operating conditions the plane would experience and the maintenance service it would receive in the field under combat conditions.
Wow I learned more from you than I learned from dozens oder books! Thank you!
Fantastic. Great job at clearing up some P-51 myths
Another great video! Can't wait for Fw-190 series!
i read in 2 books from our german pilots that they sometimes did fill and polish the whole fuselage of the 109 to achieve about 10-20km/h speed.On the downside it added weight and it wont last for long due to vibrations and stress under load. The many little openings and latches and hatches from the G model let them named it "Beule" (swelling, buckle, bump or bulge i dont know). The not fully closed wheels did reduce speed another 10-15km/h. They measured this when they upgrade into the K series. BUT fully closed wheels gave another problems f.e. at frozen wintertimes. Russians did also take them out in winter. The K series had a lot of changes too and it was all about how to get the best out of this old airframe with a much to heavy,,big and powerful engine. (remeber the first engine was about 600hp in a 109 !! so the design was for max 1000hp at that time !) And Greg i think its not fair to compare the F with the Mustang A becasue the F was a major update yes with lots of improvements BUT they cant delte or deny its original design from the early/mid 30´s ! The Mustang design was 7years younger at in wartime this means a lot !! Or lets say in the year the Mustang came out the ME262 had its first flight ;-) I think you are right in pointing out that the fully supply od all materials and perfect conditions for high end production and finishing was the key of achieving the most speed out of a given design. Perhaps a 109F produced under these perfect conditions and with much more attention to detail and finishing would have been equally fast as the Mustang but much better in climb and tight dogfights with the big downside of having shit narrow and weak undercarriage , and bad visibility,short range, low weaponry and others.
a friend shared this.
now I'm hooked
Sir Greg: as per flt.engineer , It is a Respectable Profession. I should have grabbed my RADAR CERT. @ test time, but time was pressed to review Baud Rates... TailWinds Grace ya
The P51 was the best. The BEST I tell you. So was the jug, the lightning, that gull wing thing, and others. Depends on which episode of Wings you watch.
Sorry Greg if that was a little off topic. Watching your vids has given me an appreciation for the Jug which is now a toss up for the P51.
The research that I've done suggest that the laminar flow on a P-51's wing could be all but nullified with nothing more than a few grains of debris.
That agrees with all the info I have.
Greg, this is an outstanding presentation. Excellent and very informative. Thanks.
Love the "free" commentation!
I run into this at work all the time. I am getting tired of having to explain to fellow adults why everything can't be "free".
@@GregsAirplanesandAutomobiles I'm getting tired of having to explain to fellow adults how corporations pay zero taxes - as if rather than passing along the costs of paying the tax along to their customers, they instead go out back to their money tree and pick some extra $100s to send in to the IRS...
I like the flight sim shots you include. Some 3-D artists really did some beautiful work. You may as well take advantage of it!
I feel the same way, plus it's difficult to find a lot of photos of specific 109 variants.
Another great and myth-busting video Greg, thank you.
Great information Greg I fly the vintage airplanes as a " Volunteer" ( love it !)
Keep your channel live excellent info I love all airplanes and more I know and understand the better I will be as a Pilot Thank you very much for posting and since Christmas is getting close I wish you Merry Christmas and an awesome new year !
Thank you, and Merry Christmas to you.
Thankful for a subject where drag doesn't involve men in dresses and makeup.
Its wonderful how many WWII fighter comparisons are on you tube
Hi, I have a question about drag and the bf 109 canopy. Would the frame edges from the boxier version on the late E model onwards have made a significant drag difference compared to the rounder canopy on the early 109 models? Also, I've heard claims that the bubble canopies in general have more drag than those embedded in the spine, is this true? And so could it be that the even the boxy bf109 canopy wasn't much different in drag to the bubble canopies of other fighters? Or was it still a hindrance in comparison? Cheers.
Glad to see you finally put the laminar flow canard to bed in your thread.
What I was told by my father (who served as OTU ground crew), was that it was BS for home consumption, not practical either for production, or in operational use, nor credible as propaganda since no competent German aircraft designer would buy the proposition.
IMO the most important factor regarding the airframe is probably that the Mustang was designed with a geometry which allowed a greater degree of rearward movement in operational CG, allowing a sufficient volume (weight) of fuel to be carried in the rear fuselage without degrading handling to the point where it became unacceptable in the early parts of the flight regime, even if requiring careful handling.
This was something not addressed in the design of single-engined fighters of an earlier generation (1930's) when the specifications were written for the Spit or the Me109 at a time when design philosophy was to help reduce drag by using a small tail-plane and accepting the trade off in reduced safe rearward movement in CG and when range or loiter time was not seen as a priority in the single-engined fighter role.
September 15th, 1939 "Today I reduced the coefficient of drag of the new design. After exhaustive deliberation in meetings the reference area was increased by 20% yielding a 17% reduction in Cd."
Great video Greg! I was so happy to see you had a new one..just terrific work. Thanks for all the hard work to create such informative and entertaining content. Just great!
A point of note is that the angle of fall off of the fuselage at the HE exhaust is great than 7 deg which means that this area is producing drag due to turbulent separation. The hot air coming out at high velocity essentially cancels this drag by filling the area going back to the tail wheel.
I know this isn't your specialty, @Greg, but you should collaborate with Military Aviation History or another similar channel. Also, a follow-on for the later Merlin Mustangs and other competing aircraft would be cool!
This is the follow on video. I covered the Merlin Mustangs vs 109G earlier here: ruclips.net/video/sTD7DqXfRno/видео.html . As for a collaborative effort, I'm not opposed to it, but there are very few channels I would do it with, M.A.H. and M.H.V. are two that I would, both are awesome.
Oh I will be busy at school during the premier. This will be good though, will certainly be looking forward to it.
I always figured there was more to the Mustangs aerodynamics than just its "laminar flow wings." Had a feeling the cooling system didn't become a jet engine, always looked at the airplane and figured its total design contributed to its areodynamics and not just its wings, and i knew the wings weren't super wings, just created less drag at higher rates of speed than a standard air foil, this video does a good job explaining that.
What I didn't know however is the 109s total drag is less than the mustangs at higher altitude, that's a real eye opener, I knew at sea level the Mustangs greater aero really gave it a edge in thicker air, but that's something new to think about.
13aceofspades 13: You do know the less drag of the P51 did not help it get above 41900ft or a tactical Mach better than 0.78 [ Tested art RAE Duxford] because the Brits were the only ones with Machmetres Or allow this super plane to climb better than 3475 ft/min gee what WAS it good for?
I absolutely love the comment about “free”. I need to find some fairy dust and pixie sprinkles lol
Its free for foreigners since its not their tax money lol
I have seen references to a bushing, filling/reducing the gap between wings and control surfaces (ailerons), as a contributing factor to the low drag of the P-51.
Yes, all that was a factor.
Looking forward to release
Greg, as a current day sailplane flyer let me recommend flight test evaluations of many, many glider designs done in the real world by Richard "Dick" Johnson. these are readily available through the SSA (Soaring Society of America) web site, or through a generic Google search. Laminar airflow over the wing has been the holy grail of sail plane designers since the early 70s (at least), and the designers have gone through all sorts of design strategies to keep airflow "attached" across the entire chord of sail plane wings. These range from populating the leading edges of wings with many (4-5 per inch) inlet holes and routing the pressure to the aft underside of the wings through tubes exiting at the "zone of separation", to "turbulator" strips applied at the point of flow separation in an attempt to re attach flow to the airfoil. Johnson offers practical measurements of these flows in many of his evaluations by observing the flow of oil on the wing-very informative
Measuring drag is the key, and looking at drag as a measure of absolute performance is really clear when the aircraft involved have no powerplant involved to cloud the picture!.
Modern sailplane wings have to produce good lift at low speeds (= high induced drag) in order to climb in thermals at speeds from 45 to 55 kts, yet offer low drag at higher speeds to give efficient L/D at cruise speeds-these are often from 70 to 100 kts IAS. BTW modern sailplane design and construction is virtually the domain of Germany to this day…
Per your comments regarding build quality and parasitic drag, I'll just say that after mentioning the fact that I'd taken a look at a P-51 in a museum, my Father's comment was, "Pretty rough, eh", and I could only agree. I can't really stomach looking at a modern GA aircraft and thinking of it as any kind of efficient flying machine. Even the composite examples sprout control horns, antennea, boarding steps, all sorts of fastener heads, etc.
Take a look at a modern sail plane. Composite construction is completely smooth. High modulus materials have yielded airfoil thickness ratios of 12% or less on wings with aspect ratios in excess of 22:1. There can be no surprise the these craft are currently producing L/D ratios of 50:1+
I offer these comments purely in relation to you discussion of "aerodynamic drag".
You are correct, modern sailplanes are incredible well put together.
I always figured the Mustang was built for high altitude, but if you got caught by a bF-109 under 10,000 ft… RIP.
good, solid engineering investigation work