The best thing about space is that every little detail of anything is just the tip of an iceberg made out of tons of talent and engineering and people that battled problems and solved them succesfully. Science is awesome
That really is the case with science and research. Trying to engineer an object, like the space shuttle, that undergoes a lot of loads, thermal, structural, and aerodynamic, requires developing testing new methods all the time. As Scott mention these two things, it requires loads of knowledge from different aspects involved to research these things, including knowledge in the properties of air, fundamentals of fluids in all regimes of fluid flow, but also understanding the drawbacks in testing these methods. These drawbacks are considerations that have to be taken into account when testing at scale models, like understanding what error is generated from when scaled down and how that effects the the full model. You could easily imagine that hypersonics wind tunnel testing is a lecture that could last 2 hours at minimum and, without covering the technique of performing these tests, would cover all the methods, considerations, physics, scaling, be it non-dimensional numbers or systematic error, that is considered. A well experienced scientist or professor can get down to the nitty gritty of testing in wind tunnels.
@Shawn Tipton Um no. Mathematics is simply a description. It allows the "drawing" of information, such as the electron orbital to be made and drawings of predictions of orbitals which cause atomic bonds. Wave equations don't discover chemical properties. To understand the physical universe measurements have to be made and IF they match the predictions described mathematically, THEN there is an understanding of that phenomenon. The last sentence in that comment was the same as saying "If you have a large vocabulary, it could be said you know how to write a novel". If a science career is a future goal, it would be best to understand that.
I love how Scott walked us through the thinking process of how to build a hypersonic wind tunnel. I had similar questions at each stage and he answered them immediately.
Man, I wish I was a kid again. I was desperate for science explainers like Scott in the pre-internet 90's. I remember just having to take a book's short description of this phenomena for granted, but not really understanding it until decades later in college.
The worst thing about the time before You Tube was having to rely very often on people like science journalists. So often wrong, so often subtly incorrect in ways that are not east to spot. That can mess people up technically for years or for the rest of their life.
@@Styrofo4m, yeah, I saw that video yesterday. I'm sure he'll show up as soon as all traces of the mayo are gone -- I think that camera belongs to one of his partners.
Never in a thousand years would I have ever thought to use an electron beam to ionize the gas flow in a wind tunnel to see such things on reentry simulations. The people who come up with this stuff truly have amazing minds. They basically turned the model itself into a kind of neon sign to let the gas alone show the flow and density patterns. Truly genius whoever came up with that.
I studied aeronautical engineering years ago, and got to use a wind tunnel for a project, it was subsonic, but we also had a blow down supersonic wind tunnel, that one worked by decompressing a chamber, and compressing another, and quickly releasing the pressure, and using a trigger to start a camera to record the shock waves around the model in the test section :)
I designed a supersonic blow down wind tunnel for my senior project this year. Not really, it’s actually pressure tanks going through ball valves and pressure regulators into a settling chamber, then another ball valve with air blowing through a nozzle rigged with thermocouples and pitot static probes. The idea is to cheaply manufacture nozzles for a Jetcat hobbyist turbojet, since the nozzles don’t have to withstand thermal stress from the hot exhaust. The purpose of the test rig is to simulate the Mach coming out of the turbine of my engine (M=0.918), but I have had Mach 1.9 flow coming out of it before I had the regulators dialed in properly
Yes, me to, I think the bit about all the energy being stored up as it just can't move through the gap anymore and then thinking of air exploding on the other side.
When you said "Fifty year old photo", I had to quickly do the math in disbelief of my actual age. I felt my whole day slip down a peg, on the pretty good scale of painlessly enjoyable. :) Rock-On Dr. Scott ! Always cool facts, keeping it sharp.
Some of us look at a cat video on youtube and still can't explain in simple terms what a cat is. Scott Manley sees one 50 year-old picture and, in a few minutes, explains multiple mind-blowing scientific facts via the same cat video delivery platform.
This was amazing. It's this kind of content that makes this my favorite RUclips channel! Technical content well explained without treating the viewer either as an idiot or requiring we actually do the calculations.
1:10 I visited the Eiffel wind tunnel a couple of years ago. It’s still in use for wind speeds up to 120 km/hr. You can actually walk into the tunnel - it’s person sized! For bigger objects to be tested they make a scale model. They had recently used it to test the stability of drones.
"But in the end, after testing, it was vastly more successful at converting aviation fuel into noise pollution" How much do I like these sarcastic quotes 😁
@@therflash Indeed. It was so loud it literally made people sick. "On the ground "run ups", the prototypes could reportedly be heard 25 miles (40 km) away." "The aircraft was notorious for inducing severe nausea and headaches among ground crews." "In one report, a Republic engineer suffered a seizure after close range exposure to the shock waves emanating from a powered-up XF-84H."
Yeah you pretty much needed an old priest and a young priest to get near that abomination. "The power of Christ compels thee!". As they flick holy gasoline on it.
As a mechanical engineer, I have often said to disbelieving laymen, that engineers are some of the most creative people alive. This video does a good job at validating that concept. Thank you Scott.
Thanks Scott ! This was a reminder of a great job I had in late 80's in Rocket Test for ARC ( now Aerojet I think ) that had a huge "Air Facility" as it was called in those days. I think it was an amalgam of ex NASA equipment that allowed them to test fire not models, but the actual full size SM-2 Standard Missile recreating it's entire flight profile while the motor operated, generating performance test data to qualify systems for manufacturing. They even had an expansion system around nozzle's exit to recreate lower external air pressures at altitude. It was a blowdown system with about a dozen immense tanks on railroad cars that took days to fill with the required compressed air it expended in tests. They literally flew the missile in a high speed wind tunnel while the rocket motor operated in real world test conditions ! They also did extensive ramjet testing with same facilities. I sometimes wonder if any of that stuff is still being used to test next gen systems currently ?
Impressive! I am ashamed to say I am supposed to know all this ( I do really) but would trip over myself trying to explain it to the layman. Scott does a great job leading you through the subject starting from the basics, explaining the issues and they way they have been resolved to achieve Mach 20. I am very impressed.
Don't be ashamed. Not every specialist (which I assume you are if you are supposed to know that) has to be a good teacher as well. Some people are good at accumulating knowledge and using it, but not necessarily at sharing it (actually that 'some' a significant if not vast majority of people whose brains develop in a way that causes them to take interest in complex technical concepts).
Well done, Scott. As an Aerospace engineer who has tested in wind tunnels all over the country, I get so infuriated at the regular media in talking about hypersonic. Of course they wouldn't begin to understand your discussion. Thanks.
Find an image relating to something else, in this case the previous video. Do some research on the image and realise not only is it a cool image but that a lot of engineering was required for it to even exist. Spend ages making a video
I wish they had lessons like this in school. It covers so many topics and in an interesting and engaging format! It seems like schools are more interested in confusing children instead of teaching them.
Such a cool episode! As soon as you mentioned expansion after the restriction area to increase velocity I was like “WAIT a second… thats exactly the same principle as…” and a few seconds later you mention rocket nozzles. 🤣
Forget the wind tunnels, I never understood the rocket nozzle throat thing until now, many thanks for that clear and simple explanation of how fluid physics adjusts relative to sound speed!
Brilliant lecture, as always, we're waiting for a long overdue shock wave dynamics video as promised in plutonium implosion devices, looking forward to that Scott! Peace from North Wales
Fascinating topic, completely agreed. If I may, the "Schlieren Photography" is pronounced "sh-leer-en". Schlieren is the German word for wisps or swirls, such as you get when a drop of mechanical oil glistens on a swirling patch of water in light. Not as critique, simply as pronounciation help for the future.
I live 5 miles from Langley and have seen all of that equipment up close and personal many times Now after nearly 50 years It is awesome to know how it works thank you Scott great work!!
Just absolutely impressive… you know your material extremely well when you’re able to describe it to the layman. That’s the sign of subject matter expert!
Scott, I teach engineering to high school students, and one of the classes is Aerospace engineering. I can't tell you how much I've learned from your videos, and I'm incorporating as much as I think high school seniors can understand into my classes. Thanks so much!
Back when I was an undergrad (many years ago), a friend of mine worked in a lab with a hypersonic wind tunnel. More like a cannon than what most folks think of as a wind tunnel. Anyways, they made a fun video of a paper airplane getting disintegrated by the shockwave. PS: This was at Caltech. Oh, and I'm commenting before watching Scott's video... Wondering how much is going to be familiar ;)
@@glennpearson9348 We also had one at my uni. Everytime they used it you'd hear it like a gunshot all over campus. They also had warning lights on the nearby street so that the drivers could prepare to be startled :D
I follow this channel since early ksp journey. After a casual course about the topology of fuel injection in rocket engine, here we go: a casual course about the engineering problems of high velocity wind tunnels.
WOW this was insanely interesting, and a testimony of how aparently simple things, are in reality much complex, specially when you push for the limits.
Its Friday afternoon, and I learned more about hypersonic wind-tunnels. It is great that school honed my skills at acquiring knowledge I will never need in real life. I quite enjoyed that.
This was awesome. It's great to see how some of the more analog science approaches were done when we didn't have the simulation technology we have now. Thanks for sharing Scott!
The inlet velocity of the project Pluto cruise missile nuclear reactor (ram jet engine) at the Nevada Test Site test facility needed to be Mach 3 @ 2000 degrees to PREVENT meltdown of the flow-through reactor. The engineering in that monster building and equipment was INSANE! There was a 50 acre area covered in air tubes made from something like naval rifle barrels, pumped up with submarine compressors to provide airflow for a 5 minute test. The air tank field fed four huge tanks filled with 2” stainless ball bearings that would be heated to 2000 degrees. I visited there in 2000.
Thank you Scott, most interesting. That image is just amazing. I too have seen a transonic shock, on the inner wing of a B-747-400. In my case it was visible as a stable distortion standing up above the wing surface - exactly the height I had read about as the optimal trade-off between increased fuel burn due to mach drag rise and flight time. I called over the cabin attendant - thinking she would find it as interesting as I did. No, she thought I was expecting the plane to crash or something. I still do not understand how a person who is in the airline industry can be so incurious about aerodynamics... and maybe more than a little ignorant. I took several photos, but thanks to several changes of residence, I do not know where they are now.
I have modeled, built, and tested a small wind tunnel with 3rd and 5th order contraction sections for use in calibrating instrumentation, but until now I haven’t expanded the math to include my rocketry. Your explanation completely destroyed the bridge and blew my mind. Thank you for the expansion and coalition of my interests!! Pure bliss (techno nerd sorry) :)
I think the reason for using Helium is that, temperature being proportional to the kinetic energy of gas molecules mv^2/2, the lower the mass of the molecule, the lower the temperature (and energy) needed to achieve the same velocity. That is why Helium needs much less heating than air to reach Mach 20. I think this was also used to fire a hypersonic Helium pellet gun in some video.
"50 year old photo featuring the Space Shuttle in a helium electron beam excited wind tunnel". I was 10 when we landed on the moon in 1969. That was only 52 years ago. I love this example of 50 year old serious work we and others were and are doing that is very much out of my training and scope. Kudos to the scientists, engineers, programmers, project managers, inventors.... all those people working hard in the area they aspire to and love that is making a difference in our world.
A good example of air changing temperature with pressure change can be seen in places that use pneumatically actuated machinery. It's common to have bell-style water traps inline just before the line goes into the machine. The compressor releases high pressure air into the distribution lines, cooling it in the process. From there if the atmospheric conditions are right, generally meaning the local dew point, the now colder air causes water to condense in the distribution lines, then the air flow pushes it downstream towards places you really do not want water going. The bell traps basically use gravity to catch it before it causes trouble. The bells are usually made from a clear polycarbonate so the operator can see if they're filling up. During the muggiest days with high dew points, it's not uncommon to have to drain the water multiple times a day.
Great video. In case nobody else has mentioned it, I recommend the book "Facing the Heat Barrier" by T.A. Heppenheimer. The first part of the book goes into some detail about the different wind tunnels developed during the early years of the space age, and why they were necessary. It's an absolute must-read if you are interested in how the problems of heat were solved for ICBMs, Apollo, the X-15 and Space Shuttle.
Thank you, Scott, for this excellent lecture on these amazing subjects. I thought I understood windtunnels from back in uni but never realized hypersonic speeds present such extreme challenges. I loved to hear you describe my line of thoughts just when I started seeing the similarity of rocket nozzles! That was a great trick! It makes me wonder which came first - the hypersonic windtunnel or the rocket nozzle? But again, massive thanks for this awesome post! 👌
It's a very late answer, but the rocket nozzle came first - the converging-diverging (De Laval) nozzle was first used in a rocket in 1915 by Robert Goddard. By late-WW2 Germany had wind tunnels that could operate at up to Mach 4.4 and possibly even as high as Mach 5 intermittently. They were also in the process of building one that would reach Mach 7-10. In 1947 John Becker at NACA Langley built a small testbed hypersonic tunnel that reached Mach 6.9 in 1947 - the first hypersonic wind tunnel in the US.
Excellent discussion of basic wind tunnel operations. As an aero engineer it was a fun review. The US Air Force has a facility in Tullahoma, Tennessee that has wind tunnels that run tests from sub sonic to hypersonic. I walked through the the test section of the transonic tunnel that could hold very large scale models (about 20’) for testing.
This is way more interesting than I expected. The nozzle based design like in a rocket and the liquification of the air after Mach 4 blew my mind. Btw Schlieren is a German word meaning something like a line of smudges on a surface. It's pronounced more closer to Shlee-ren then what you said.
Would absolutely love you to do a few videos or a playlist on the basics of fluid dynamics, these videos are so well explained, I feel it could be really helpful for a lot of people
Speaking of wind tunnels, please please feel free to use our open source wind tunnel to use for schools and other activities or just for yourself to have fun. You can find it in our channels. Go ahead and enjoy it.
When growing up in Madison, AL, I used to live down the road from Wyle Lab’s wind tunnel. I think they helped NASA test the shuttle’s aerodynamics there. Whenever Wyle conducted a test, there was always a low-frequency sound that made all the windows rattle. I can definitely see why now after watching this very informative video.
Hi Scott. Helium and Hydrogen both have negative joule-Thompson coefficients, which mean they actually heat up in stead of cool down when throttled through an orifice. Maybe that is part of the reason for using Helium here as well. Thanks for an awesome video as always!
Scott… I’ve watching your videos for sometime now and just wanted to say THANK YOU. I love your how you explain technical things and you make the viewer never to feel dumb. This particular video was fascinating as I never thought about hypersonic testing requirements before. Keep up the excellent work that you do for us!!!!!
The ‘ie’ “Schlieren”-technique is actually pronounced like the ‘ee’ in the English word “eerie”. (Sorry, but it is a German word. It literally means “smears”. And while Germans don’t know everything, they sure know everything better.) BTW: I noticed that Scott’s eyes looked weird in some videos. Now I know why: it is the reflection of the circular light he is using in his recording set-up. Nice video with interesting details. Thanks!
my entire life anytime I heard the term "supersonic or hypersonic wind tunnel" I always wondered how the heck they would ever achieve those speeds in a wind tunnel. this has been very enlightening for me. thank you for the great video!
I was amazed to discover that the Germans had a Mach 5 wind tunnel in Penemunde. I guess this was a high priority article for operation paperclip, seeing how rare and sofisticated these things are. Still, to think they where doing this kind of engineering almost 80 years ago.... Mind blowing.
In the lobby of U.S. Food and Drug Administration building (just outside the beltway of Washington DC) there is a huge abstract composition named _"Prototype for Re-Entry"_. It represents a V-2 missile and it is there only because this was the location where these German wind tunnels were installed after the war. It was called White Oak Naval Ordnance Laboratory then. The tunnels were operated by US personnel with the help of 12 German scientists from Peenemünde.
For whatever strange reason, all sorts of awesome videos on RUclips have at least some thumbs down votes. But this one doesn't and it truly deserves this special medal. Loved every second of it!
Awesome video. From someone who has been working in everything from a 7'X10' 100PSF low speed tunnel to a MACH 6 quiet tunnel to a MACH~'we're not sure just how fast we can go" Hypersonic Expansion Tunnel using a Helium slug. Now my days are spent developing new laser based analytical techniques for hypersonics research. This was a fantastic explanation of how wind tunnels work and why there aren't too many hypersonic facilities.
I know for a fact that I will never deal with wind tunnels in my whole life, but the joy of learning new things and adding new questions after them is so pure and sweet that I can not miss it. And you, dear Scott, have a special part in this whole story. thank you.👍❤️
I always come back to your channel every once in a while because it’s exactly just technical enough while also not feeling like a lecture Keep up the good work Scott!
Usually when you explain the physics behind certain complex topics no I have to watch it a couple of times before I get it but this video I was able to understand pretty much everything you said in one watch. It's a testament to how well you know this topic as you are able to explain it so simply.
Good engineering job! The difference between theory and practice ... It reminds me of my lessons in pressure hydraulics, where we learned that from a certain flow, a given section could not swallow more: you can always increase the pressure , no more material will pass in this section. Super interesting to see the technique of these hypersonic test tunnels !!!! Ah, the great Bernoulli (and St Venant !!!) ... As tall as Einstein for hydraulics ... Greetings from France
That is really amazing. I saw the low speed wind tunnel at Langley, decades ago. There is (or was) a RUclips film about how its giant, wooden propellers were built. I hadn't given much thought about supersonic, much less hypersonic, tunnels. Your explanation of the problems and solutions for these is fascinating. I really enjoyed it.
That's amazing. Being able to put together a whole bunch of different processes and principles to create something that lets you *see* the density of the air, and do it under such extreme conditions... I never fail to be impressed by ingenious solutions like this.
You mentioned that wind tunnels use vast amounts of power. In the 1980's I worked at a nuclear power plant (Surry) that was close to the Langley 30 by 60 foot wind tunnel. Surry put out about 2000 megawatts of electricity. When the wind tunnel would start, the power draw on the grid would slow down the generators and lower the frequency across the Virginia grid, and the operators at the plant would have to adjust nuclear power to compensate. A staggering amount of power was being drawn.
WONDERFUL video. This is why we come here. Thank you Scott. (PS - why didn't they just use the whirlpool vortex at the end of your video? WAY over mach 20, I'll bet.)
Again one of the best videos ever. Nobody does it better than Scott! Thank you very much for the simple, comprehensible and very interesting information about what seems to be a simple computer animated image, but is in fact far more!
As a aerospace engineering technician at Langley Research Center for 36 years our job was to install instrument and run the wind tunnels. I worked and operated in over 20 wind tunnels during my career. The 20” Mach 20 Helium tunnel shown here and described by Scott was described accurately for the reason for the use of Helium gas. After purification of the helium gas we increased the gas pressure I believe ( sorry I retired 20 years ago) 3000 psi. When the isolation valve for the tunnel to the vacuum sphere was open the 3000 psi helium supply valves were opened and the gas raced thru the orifice and generated Mach 20. No heating of the helium was required. Many years were spent in this and other NASA facilities to develop the final shuttle shape. I also worked in the Mach 6 2’x2’ tunnel air in the D wing of Gas Dynamic building 1247 at Langley. To develop Mach 6 with 600 psi air the air was heater to about 425 + degrees to insure the air would not become liquid as it accelerates to Mach 6 thru the nozzle which causes a drop in temperature. If not hot enough the air would liquify into air and droplets of air and invalidate the data. So if we used air at Mach 20 what temperature of the air would be required to prevent liquefaction- above my pay grade but probably several thousand degrees. So what material in the structure of tunnels valves and hardware would be required to withstand those temperatures - materials we did not have therefore helium was used. I point I noticed in the comments I was technician and had the the immense honor of working with some of the brightest aerospace engineers and managers in our country - these brilliant engineers these public servants worked tirelessly long hours with pay well below many other in the private sector and were true patriots.
This is the type of content that sets this channel apart from others, just goes to show how you dont need fancy graphics to really explore cool things.
The best thing about space is that every little detail of anything is just the tip of an iceberg made out of tons of talent and engineering and people that battled problems and solved them succesfully. Science is awesome
People sciencing is awesome too !
That’s true if nearly everything, from pencils to the socks you’re wearing, to the phone you’re watching this on.
Well said!
That really is the case with science and research. Trying to engineer an object, like the space shuttle, that undergoes a lot of loads, thermal, structural, and aerodynamic, requires developing testing new methods all the time. As Scott mention these two things, it requires loads of knowledge from different aspects involved to research these things, including knowledge in the properties of air, fundamentals of fluids in all regimes of fluid flow, but also understanding the drawbacks in testing these methods. These drawbacks are considerations that have to be taken into account when testing at scale models, like understanding what error is generated from when scaled down and how that effects the the full model.
You could easily imagine that hypersonics wind tunnel testing is a lecture that could last 2 hours at minimum and, without covering the technique of performing these tests, would cover all the methods, considerations, physics, scaling, be it non-dimensional numbers or systematic error, that is considered. A well experienced scientist or professor can get down to the nitty gritty of testing in wind tunnels.
@Shawn Tipton Um no. Mathematics is simply a description. It allows the "drawing" of information, such as the electron orbital to be made and drawings of predictions of orbitals which cause atomic bonds. Wave equations don't discover chemical properties.
To understand the physical universe measurements have to be made and IF they match the predictions described mathematically, THEN there is an understanding of that phenomenon.
The last sentence in that comment was the same as saying "If you have a large vocabulary, it could be said you know how to write a novel".
If a science career is a future goal, it would be best to understand that.
Really cool how a single image can spark curiosity and learning about some very interesting science. Great video Scott.
Hey Mr Minecraft man!
Heya cub!
What are you doing here hermit?
Whoa, did not expect to see you here, Cub! Nice!
Cant lie i really did not expect cupfan in here
I love how Scott walked us through the thinking process of how to build a hypersonic wind tunnel. I had similar questions at each stage and he answered them immediately.
Very very good at this, I agree! Imagine if you always had teaching/learning in this matter!
Man, I wish I was a kid again. I was desperate for science explainers like Scott in the pre-internet 90's. I remember just having to take a book's short description of this phenomena for granted, but not really understanding it until decades later in college.
This, now today its 3 sorts of problems. The easy ones like how to make an hyper sonic wind tunnel. Stuff none know and stuff you can not google :)
@@magnemoe1 well, texted,🤔
Carl Sagan, perhaps?
As a kid, I’m seriously grateful to have so many opportunities. Thanks to all who came before me, who made this life possible
The worst thing about the time before You Tube was having to rely very often on people like science journalists. So often wrong, so often subtly incorrect in ways that are not east to spot. That can mess people up technically for years or for the rest of their life.
I'm surprised Destin from Smarter Every Day didn't get summoned when you said "laminar flow" at 1:25.
You have to say it 3 times while looking in the mirror.
@@CxOrillion yes a mirror made of laminar flow.
@@Styrofo4m XD
@@Styrofo4m, yeah, I saw that video yesterday. I'm sure he'll show up as soon as all traces of the mayo are gone -- I think that camera belongs to one of his partners.
I thought you had to make a circle out of snatch blocks when saying laminar flow in the mirror for him to appear
Never in a thousand years would I have ever thought to use an electron beam to ionize the gas flow in a wind tunnel to see such things on reentry simulations. The people who come up with this stuff truly have amazing minds. They basically turned the model itself into a kind of neon sign to let the gas alone show the flow and density patterns. Truly genius whoever came up with that.
"ionizing the gas flow" would be a bit overkill tho
@@smort123 wellll....that's what it does.
Lsd
@@smort123 That's literally what it does...
Old TVs had electron beams in them. Cathode ray tube. There's no such thing as a cathode-ray but there is such a thing as an electron beam 😁
I studied aeronautical engineering years ago, and got to use a wind tunnel for a project, it was subsonic, but we also had a blow down supersonic wind tunnel, that one worked by decompressing a chamber, and compressing another, and quickly releasing the pressure, and using a trigger to start a camera to record the shock waves around the model in the test section :)
I designed a supersonic blow down wind tunnel for my senior project this year. Not really, it’s actually pressure tanks going through ball valves and pressure regulators into a settling chamber, then another ball valve with air blowing through a nozzle rigged with thermocouples and pitot static probes. The idea is to cheaply manufacture nozzles for a Jetcat hobbyist turbojet, since the nozzles don’t have to withstand thermal stress from the hot exhaust. The purpose of the test rig is to simulate the Mach coming out of the turbine of my engine (M=0.918), but I have had Mach 1.9 flow coming out of it before I had the regulators dialed in properly
I FINALLY understand how converging/diverging nozzles work! Something about this explanation made it click for me
Yes, me to, I think the bit about all the energy being stored up as it just can't move through the gap anymore and then thinking of air exploding on the other side.
Agreed. A better explanation than most college engineering textbooks as far as just explaining the concept.
Me too!
SAME!!!
When you said "Fifty year old photo", I had to quickly do the math in disbelief of my actual age. I felt my whole day slip down a peg, on the pretty good scale of painlessly enjoyable. :) Rock-On Dr. Scott ! Always cool facts, keeping it sharp.
I was all but a baby when the space shuttle started. Even I felt that one! 😅
@@Zacks.C-land I watched STS-1, being held by mother, the day after I was born. It was painful when the Space Shuttle was decommissioned in 2011.
Some of us look at a cat video on youtube and still can't explain in simple terms what a cat is. Scott Manley sees one 50 year-old picture and, in a few minutes, explains multiple mind-blowing scientific facts via the same cat video delivery platform.
And 67 people thumb this down 🤦♂️
To be fair, cats are enigmatic creatures with mysterious and devious motivations. Hypersonic fluid dynamics is easy stuff to explain in comparison.
An endothermic quadriped, carnivorous by nature.
@@OphisUK That sure narrows it down for me, LOL
This was a fascinating topic and a fabulous job explaining it.
I have to say, I've never put it together that rocket engines and wind tunnels are so closely related.
One of those "Oh yeah!" moments.
This was amazing. It's this kind of content that makes this my favorite RUclips channel! Technical content well explained without treating the viewer either as an idiot or requiring we actually do the calculations.
100% agree with you. Very interesting subjects that were well researched and explained perfectly. Thanks Scott!
1:10 I visited the Eiffel wind tunnel a couple of years ago. It’s still in use for wind speeds up to 120 km/hr. You can actually walk into the tunnel - it’s person sized! For bigger objects to be tested they make a scale model. They had recently used it to test the stability of drones.
Do they test weather men in it to see if they can handle a storm? :-)
@@zapfanzapfan It would definitely be a test of their toupee glue!!!
What happened to your face [? & ?]
"But in the end, after testing, it was vastly more successful at converting aviation fuel into noise pollution" How much do I like these sarcastic quotes 😁
best bit is that's not even sarcasm, thats just an objective statement xD
@@thesherbet Noise polution is a tad of an understatement.
I had tears in my eyes after he said that because of laughter
@@therflash Indeed. It was so loud it literally made people sick.
"On the ground "run ups", the prototypes could reportedly be heard 25 miles (40 km) away."
"The aircraft was notorious for inducing severe nausea and headaches among ground crews."
"In one report, a Republic engineer suffered a seizure after close range exposure to the shock waves emanating from a powered-up XF-84H."
Yeah you pretty much needed an old priest and a young priest to get near that abomination. "The power of Christ compels thee!". As they flick holy gasoline on it.
This must be one of your best videos ever. Really succinct explanation and enjoyable narration.
We just covered wind tunnels and flows in my aerospace engineering course! It feels awesome to really understand everything going on in this video.
We just started compressible flow in my thermo/aero class. What uni do you go to?
@@will3346 And I'm just finishing compressible flow in my Applied fluid dynamics unit! hahaha big world
@@will3346 Ohio State, what about you?
@@Spashium Ah nice I go to Georgia Tech. What’s Ohio state like?
As a mechanical engineer, I have often said to disbelieving laymen, that engineers are some of the most creative people alive. This video does a good job at validating that concept. Thank you Scott.
yes as an engineer when i hear artists say they are creators i always think to myself yah what do they actually create?
@@ronblack7870 I totally agree. I'd like to think the flush toilet is of more practical worth than all the art ever produced.
Bingo. It applies to theoretical sciences too, they're full of thought experiments, abstract concepts or infinitely unreachable situations
Why y’all gotta be so negative lol, no shit art doesn’t have practical uses like engineering, but people enjoy it.
Thanks Scott ! This was a reminder of a great job I had in late 80's in Rocket Test for ARC ( now Aerojet I think ) that had a huge "Air Facility" as it was called in those days. I think it was an amalgam of ex NASA equipment that allowed them to test fire not models, but the actual full size SM-2 Standard Missile recreating it's entire flight profile while the motor operated, generating performance test data to qualify systems for manufacturing. They even had an expansion system around nozzle's exit to recreate lower external air pressures at altitude. It was a blowdown system with about a dozen immense tanks on railroad cars that took days to fill with the required compressed air it expended in tests. They literally flew the missile in a high speed wind tunnel while the rocket motor operated in real world test conditions ! They also did extensive ramjet testing with same facilities. I sometimes wonder if any of that stuff is still being used to test next gen systems currently ?
Impressive! I am ashamed to say I am supposed to know all this ( I do really) but would trip over myself trying to explain it to the layman. Scott does a great job leading you through the subject starting from the basics, explaining the issues and they way they have been resolved to achieve Mach 20. I am very impressed.
Don't be ashamed. Not every specialist (which I assume you are if you are supposed to know that) has to be a good teacher as well. Some people are good at accumulating knowledge and using it, but not necessarily at sharing it (actually that 'some' a significant if not vast majority of people whose brains develop in a way that causes them to take interest in complex technical concepts).
Get some knee pads why don’t ya
@@WhiteOwlOnFire_XXX It's actually ok to appreciate people and/or things.
Well done, Scott. As an Aerospace engineer who has tested in wind tunnels all over the country, I get so infuriated at the regular media in talking about hypersonic. Of course they wouldn't begin to understand your discussion. Thanks.
"Bernoulli's most obvious law" I love that!
This stuff is also yet another example of the science that needs helium that we keep hearing about.
Yeah yet another reason we must end the accursed use of precious terrestrial helium for fing party balloons....
@@Dragrath1 yep . i hope they recover the hel. from those vac. tanks.
like the university on periodicvideos
I am often impressed by how good and specific to the subject the visuals in these videos are. How do you usually go about finding the right images?
Find an image relating to something else, in this case the previous video. Do some research on the image and realise not only is it a cool image but that a lot of engineering was required for it to even exist. Spend ages making a video
I wish they had lessons like this in school. It covers so many topics and in an interesting and engaging format! It seems like schools are more interested in confusing children instead of teaching them.
And stressing them out too.
You're not badmouthing Drag Queen Story Time Reading, are you?
@@demef758 if the shoe fits...
In 1968 I was stationed at NAS Moffet Field were Nasa Ames Research center. The wind tunnel would keep us awake ,great stuff
Such a cool episode! As soon as you mentioned expansion after the restriction area to increase velocity I was like “WAIT a second… thats exactly the same principle as…” and a few seconds later you mention rocket nozzles. 🤣
Forget the wind tunnels, I never understood the rocket nozzle throat thing until now, many thanks for that clear and simple explanation of how fluid physics adjusts relative to sound speed!
Brilliant lecture, as always, we're waiting for a long overdue shock wave dynamics video as promised in plutonium implosion devices, looking forward to that Scott!
Peace from North Wales
Fascinating topic, completely agreed.
If I may, the "Schlieren Photography" is pronounced "sh-leer-en". Schlieren is the German word for wisps or swirls, such as you get when a drop of mechanical oil glistens on a swirling patch of water in light. Not as critique, simply as pronounciation help for the future.
It took me 7 minutes of watching this video before I realized Scott was wearing merch.
I love your videos! You were part of my child/teenage years! Thank you so much
It took untill after the video reading the comments for me.
Why are you here
I was trying to figure out what that was.
Shows you were concentrating on what he was saying
I live 5 miles from Langley and have seen all of that equipment up close and personal many times Now after nearly 50 years
It is awesome to know how it works thank you Scott great work!!
Just absolutely impressive… you know your material extremely well when you’re able to describe it to the layman. That’s the sign of subject matter expert!
Scott, I teach engineering to high school students, and one of the classes is Aerospace engineering. I can't tell you how much I've learned from your videos, and I'm incorporating as much as I think high school seniors can understand into my classes. Thanks so much!
My university has a mach 10+ wind tunnel, it doesn't run for very long though. I would love to get to use it one day.
If you stood in it while it was operating, I imagine it would do with you the same thing that carburetor does to a droplet of fuel.
What uni?
Back when I was an undergrad (many years ago), a friend of mine worked in a lab with a hypersonic wind tunnel. More like a cannon than what most folks think of as a wind tunnel. Anyways, they made a fun video of a paper airplane getting disintegrated by the shockwave.
PS: This was at Caltech. Oh, and I'm commenting before watching Scott's video... Wondering how much is going to be familiar ;)
Texas A&M also has a hypersonic wind tunnel. Damn thing is loud!
@@glennpearson9348 We also had one at my uni. Everytime they used it you'd hear it like a gunshot all over campus. They also had warning lights on the nearby street so that the drivers could prepare to be startled :D
I follow this channel since early ksp journey. After a casual course about the topology of fuel injection in rocket engine, here we go: a casual course about the engineering problems of high velocity wind tunnels.
WOW this was insanely interesting, and a testimony of how aparently simple things, are in reality much complex, specially when you push for the limits.
Its Friday afternoon, and I learned more about hypersonic wind-tunnels. It is great that school honed my skills at acquiring knowledge I will never need in real life. I quite enjoyed that.
Hi Scott - why are you so awesome!!! This is once again an amazing story about several amazing physical effects. KEEP IT COMING!
This was awesome. It's great to see how some of the more analog science approaches were done when we didn't have the simulation technology we have now. Thanks for sharing Scott!
Very well explained, Scott. I love that Saturn-5 rocket model! Seeing it takes me back to when I was a kid, watching Apollo 11 land on the moon.
The inlet velocity of the project Pluto cruise missile nuclear reactor (ram jet engine) at the Nevada Test Site test facility needed to be Mach 3 @ 2000 degrees to PREVENT meltdown of the flow-through reactor. The engineering in that monster building and equipment was INSANE! There was a 50 acre area covered in air tubes made from something like naval rifle barrels, pumped up with submarine compressors to provide airflow for a 5 minute test. The air tank field fed four huge tanks filled with 2” stainless ball bearings that would be heated to 2000 degrees. I visited there in 2000.
Thank you Scott, most interesting. That image is just amazing.
I too have seen a transonic shock, on the inner wing of a B-747-400. In my case it was visible as a stable distortion standing up above the wing surface - exactly the height I had read about as the optimal trade-off between increased fuel burn due to mach drag rise and flight time. I called over the cabin attendant - thinking she would find it as interesting as I did. No, she thought I was expecting the plane to crash or something. I still do not understand how a person who is in the airline industry can be so incurious about aerodynamics... and maybe more than a little ignorant.
I took several photos, but thanks to several changes of residence, I do not know where they are now.
I have modeled, built, and tested a small wind tunnel with 3rd and 5th order contraction sections for use in calibrating instrumentation, but until now I haven’t expanded the math to include my rocketry. Your explanation completely destroyed the bridge and blew my mind. Thank you for the expansion and coalition of my interests!! Pure bliss (techno nerd sorry) :)
I think the reason for using Helium is that, temperature being proportional to the kinetic energy of gas molecules mv^2/2, the lower the mass of the molecule, the lower the temperature (and energy) needed to achieve the same velocity. That is why Helium needs much less heating than air to reach Mach 20. I think this was also used to fire a hypersonic Helium pellet gun in some video.
Cool how many people still watch highly technical videos instead of just entertaining ones, makes me less disappointed in the internet
That was a great explanation, really interesting stuff!
"50 year old photo featuring the Space Shuttle in a helium electron beam excited wind tunnel". I was 10 when we landed on the moon in 1969. That was only 52 years ago. I love this example of 50 year old serious work we and others were and are doing that is very much out of my training and scope. Kudos to the scientists, engineers, programmers, project managers, inventors.... all those people working hard in the area they aspire to and love that is making a difference in our world.
“converting aviation fuel into noise pollution” is such a fantastic descriptor omg
A good example of air changing temperature with pressure change can be seen in places that use pneumatically actuated machinery. It's common to have bell-style water traps inline just before the line goes into the machine.
The compressor releases high pressure air into the distribution lines, cooling it in the process. From there if the atmospheric conditions are right, generally meaning the local dew point, the now colder air causes water to condense in the distribution lines, then the air flow pushes it downstream towards places you really do not want water going.
The bell traps basically use gravity to catch it before it causes trouble. The bells are usually made from a clear polycarbonate so the operator can see if they're filling up. During the muggiest days with high dew points, it's not uncommon to have to drain the water multiple times a day.
Great video. In case nobody else has mentioned it, I recommend the book "Facing the Heat Barrier" by T.A. Heppenheimer. The first part of the book goes into some detail about the different wind tunnels developed during the early years of the space age, and why they were necessary. It's an absolute must-read if you are interested in how the problems of heat were solved for ICBMs, Apollo, the X-15 and Space Shuttle.
Came to post about this book!
As part of the lab in my college we had a blow down supersonic tunnel. It was small but we could visualize the shock waves.
Thank you, Scott, for this excellent lecture on these amazing subjects. I thought I understood windtunnels from back in uni but never realized hypersonic speeds present such extreme challenges. I loved to hear you describe my line of thoughts just when I started seeing the similarity of rocket nozzles! That was a great trick!
It makes me wonder which came first - the hypersonic windtunnel or the rocket nozzle?
But again, massive thanks for this awesome post! 👌
It's a very late answer, but the rocket nozzle came first - the converging-diverging (De Laval) nozzle was first used in a rocket in 1915 by Robert Goddard. By late-WW2 Germany had wind tunnels that could operate at up to Mach 4.4 and possibly even as high as Mach 5 intermittently. They were also in the process of building one that would reach Mach 7-10. In 1947 John Becker at NACA Langley built a small testbed hypersonic tunnel that reached Mach 6.9 in 1947 - the first hypersonic wind tunnel in the US.
One of your best videos - thanks
dang that's a nice thumbnail
Excellent discussion of basic wind tunnel operations. As an aero engineer it was a fun review. The US Air Force has a facility in Tullahoma, Tennessee that has wind tunnels that run tests from sub sonic to hypersonic. I walked through the the test section of the transonic tunnel that could hold very large scale models (about 20’) for testing.
This is way more interesting than I expected. The nozzle based design like in a rocket and the liquification of the air after Mach 4 blew my mind. Btw Schlieren is a German word meaning something like a line of smudges on a surface. It's pronounced more closer to Shlee-ren then what you said.
Would absolutely love you to do a few videos or a playlist on the basics of fluid dynamics, these videos are so well explained, I feel it could be really helpful for a lot of people
Speaking of wind tunnels, please please feel free to use our open source wind tunnel to use for schools and other activities or just for yourself to have fun. You can find it in our channels. Go ahead and enjoy it.
When growing up in Madison, AL, I used to live down the road from Wyle Lab’s wind tunnel. I think they helped NASA test the shuttle’s aerodynamics there. Whenever Wyle conducted a test, there was always a low-frequency sound that made all the windows rattle. I can definitely see why now after watching this very informative video.
Hi Scott. Helium and Hydrogen both have negative joule-Thompson coefficients, which mean they actually heat up in stead of cool down when throttled through an orifice. Maybe that is part of the reason for using Helium here as well. Thanks for an awesome video as always!
Scott… I’ve watching your videos for sometime now and just wanted to say THANK YOU. I love your how you explain technical things and you make the viewer never to feel dumb. This particular video was fascinating as I never thought about hypersonic testing requirements before. Keep up the excellent work that you do for us!!!!!
The ‘ie’ “Schlieren”-technique is actually pronounced like the ‘ee’ in the English word “eerie”. (Sorry, but it is a German word. It literally means “smears”. And while Germans don’t know everything, they sure know everything better.)
BTW: I noticed that Scott’s eyes looked weird in some videos. Now I know why: it is the reflection of the circular light he is using in his recording set-up.
Nice video with interesting details. Thanks!
my entire life anytime I heard the term "supersonic or hypersonic wind tunnel" I always wondered how the heck they would ever achieve those speeds in a wind tunnel. this has been very enlightening for me. thank you for the great video!
I was amazed to discover that the Germans had a Mach 5 wind tunnel in Penemunde.
I guess this was a high priority article for operation paperclip, seeing how rare and sofisticated these things are.
Still, to think they where doing this kind of engineering almost 80 years ago.... Mind blowing.
In the lobby of U.S. Food and Drug Administration building (just outside the beltway of Washington DC) there is a huge abstract composition named _"Prototype for Re-Entry"_. It represents a V-2 missile and it is there only because this was the location where these German wind tunnels were installed after the war. It was called White Oak Naval Ordnance Laboratory then. The tunnels were operated by US personnel with the help of 12 German scientists from Peenemünde.
Wow, maybe your best explained video to date, storytelling-wise. Great pacing, great narrative, well done Scott!
helium at Mach 20 is pretty hardcore
lol. when you put it that way. Haha
You make rocket science so accessible. It's incredible, thank you Scott.
Bernoulli might be spinning in his grave over all the misunderstandings of his theory... but no physicist can agree on how he spins.
For whatever strange reason, all sorts of awesome videos on RUclips have at least some thumbs down votes. But this one doesn't and it truly deserves this special medal. Loved every second of it!
Was more succesful at turning aviation fuel into noise pollution xD
Loved that line.
Awesome video. From someone who has been working in everything from a 7'X10' 100PSF low speed tunnel to a MACH 6 quiet tunnel to a MACH~'we're not sure just how fast we can go" Hypersonic Expansion Tunnel using a Helium slug. Now my days are spent developing new laser based analytical techniques for hypersonics research. This was a fantastic explanation of how wind tunnels work and why there aren't too many hypersonic facilities.
My fluid engineering teacher taught me "the only way to convert subsonic flow into supersonic flow is the throat of a duck"
QUACK!
I know for a fact that I will never deal with wind tunnels in my whole life, but the joy of learning new things and adding new questions after them is so pure and sweet that I can not miss it. And you, dear Scott, have a special part in this whole story. thank you.👍❤️
"Schlieren" is pronounced "Schleeren" not "Schliren
You are amazing when it comes to explaining things with great illustrations and graphics. Thank you.
I always come back to your channel every once in a while because it’s exactly just technical enough while also not feeling like a lecture
Keep up the good work Scott!
Great video! Lot's of stuff I knew (and some I didn't), but hadn't put together into the application of a wind tunnel!
Fascinating topic! It amazes me how you always come up with great videos I didn't even know were a thing, thank you a lot for your work Scott
Wow. That was way more complicated than I would have imagined! Fascinating too!
Usually when you explain the physics behind certain complex topics no I have to watch it a couple of times before I get it but this video I was able to understand pretty much everything you said in one watch. It's a testament to how well you know this topic as you are able to explain it so simply.
One of the only channels I like the videos before I even watch them. Thanks Scott
For me, this has been the best explanation of any scientific/engineering concept ever, so thanks man!
Good engineering job! The difference between theory and practice ... It reminds me of my lessons in pressure hydraulics, where we learned that from a certain flow, a given section could not swallow more: you can always increase the pressure , no more material will pass in this section. Super interesting to see the technique of these hypersonic test tunnels !!!! Ah, the great Bernoulli (and St Venant !!!) ... As tall as Einstein for hydraulics ...
Greetings from France
That is really amazing. I saw the low speed wind tunnel at Langley, decades ago. There is (or was) a RUclips film about how its giant, wooden propellers were built. I hadn't given much thought about supersonic, much less hypersonic, tunnels. Your explanation of the problems and solutions for these is fascinating. I really enjoyed it.
I thought that i saw a shock spike while traveling in commercial aircraft when the light was just right. Thanks for confirming.
That's amazing. Being able to put together a whole bunch of different processes and principles to create something that lets you *see* the density of the air, and do it under such extreme conditions... I never fail to be impressed by ingenious solutions like this.
You mentioned that wind tunnels use vast amounts of power. In the 1980's I worked at a nuclear power plant (Surry) that was close to the Langley 30 by 60 foot wind tunnel. Surry put out about 2000 megawatts of electricity. When the wind tunnel would start, the power draw on the grid would slow down the generators and lower the frequency across the Virginia grid, and the operators at the plant would have to adjust nuclear power to compensate. A staggering amount of power was being drawn.
WONDERFUL video. This is why we come here. Thank you Scott. (PS - why didn't they just use the whirlpool vortex at the end of your video? WAY over mach 20, I'll bet.)
This might be one of your best videos.
You explain it very well, even things that I as a trained engineer didn't know.
Long time viewer here - and this is one of your best. 1.3m subscribers later…. you still got it!
Well, I had to watch a video on wind tunnels to finally understand why the exhaust gas accelerates in a rocket engine nozzle. Thanks, Scott!
Ok, at first I was confused, thinking about rocket nozzles but 4:48 explained all of it. I learn so much from you Scott, thanks!
It's amazing all the complex engineering that went into taking that photo. Great explanation of it!
Again one of the best videos ever. Nobody does it better than Scott! Thank you very much for the simple, comprehensible and very interesting information about what seems to be a simple computer animated image, but is in fact far more!
I was an apprentice at the NGTE Pyestock supersonic wind tunnel (now a cow pasture). Thanks for updating me a little. Sixty years. . .
As a aerospace engineering technician at Langley Research Center for 36 years our job was to install instrument and run the wind tunnels. I worked and operated in over 20 wind tunnels during my career.
The 20” Mach 20 Helium tunnel shown here and described by Scott was described accurately for the reason for the use of Helium gas. After purification of the helium gas we increased the gas pressure I believe ( sorry I retired 20 years ago) 3000 psi. When the isolation valve for the tunnel to the vacuum sphere was open the 3000 psi helium supply valves were opened and the gas raced thru the orifice and generated Mach 20. No heating of the helium was required. Many years were spent in this and other NASA facilities to develop the final shuttle shape.
I also worked in the Mach 6 2’x2’ tunnel air in the D wing of Gas Dynamic building 1247 at Langley. To develop Mach 6 with 600 psi air the air was heater to about 425 + degrees to insure the air would not become liquid as it accelerates to Mach 6 thru the nozzle which causes a drop in temperature. If not hot enough the air would liquify into air and droplets of air and invalidate the data.
So if we used air at Mach 20 what temperature of the air would be required to prevent liquefaction- above my pay grade but probably several thousand degrees. So what material in the structure of tunnels valves and hardware would be required to withstand those temperatures - materials we did not have therefore helium was used.
I point I noticed in the comments I was technician and had the the immense honor of working with some of the brightest aerospace engineers and managers in our country - these brilliant engineers these public servants worked tirelessly long hours with pay well below many other in the private sector and were true patriots.
Quality content once again. Informative, fun and easy to follow. You're among the best creators to follow on YT. Thanks Scott !
You are sooo becoming my favorite YTer- I'm totally hooked!
This is the type of content that sets this channel apart from others, just goes to show how you dont need fancy graphics to really explore cool things.
Your technical storytelling skills are unrivaled, sir. That is some dry matter to explain, but it was super-engaging, chapeau!
Honestly, one of the most interesting videos I've even watched. Thanks Scott!