The engineering required to fly fast (GVT)

[@jodyolivent8481]

As a professional in the vibration analysis industry, you guys really peaked my geek! This testing is so awesome and above and beyond what many experimental kits receive. Please let Sam Jaeger know that I was happy to hear him explain the testing he was doing and thoroughly enjoyed the technicality of it all.

[@balikis]

Exactly! It was very pleasing to listen to the explanations.

[@DarkAeroInc]

Special thank you to Mike Sracic PhD for your support and technical guidance on the ground vibration testing!

[@johns.1898]

Do an even more in-depth video! I'm in aerospace and I'd love to know more about structures and FSI. Was any of the code/programs used open source?

[@danbenson7587]

Suggest checking into phenomena of “rudder lock” which affects high aspect ratio fins/rudders.

[@BlackThrasherrr]

I'm a senior in aerospace engineering, I'm currently taking a vibrations class talking about this very subject! This video is so interesting and really helped me to visualize some of the concepts we are covering, thank you!!

[@DarkAeroInc]

That’s awesome! Really happy to hear you found value in the video. :)

[@Carboneye7]

Dude if your expensive college education can’t get the point across yet a guy on KZbin can, This should be evidence of the college ruse debt scam

[@ゆっくり鑑賞アカウント]

University provide order in study. Even if we can reach certain information, it doesn't necessarily mean we can learn without guide.

[@logankistler]

@@Carboneye7the video does a great job at a succinct overview that is easily digestible. However, after the video are you able to model and perform the complex calculations necessary to analyze your own systems? How about diagnosing your modeling framework when calculations don't reflect observations? This is where the thousands of hours of coursework come in that are required to become proficient in an subject.

[@jacksontuttle8967]

I really appreciate these educational type videos because I am going through controls rights now and it's nice to see why I am learning all this stuff :)

[@almosh3271]

I design, build and fly radio controlled airplanes as a hobby. I totaly enjoyed this clip. In short I geeked out to the max and I LOVED it. Way to go and two thumbs up!!!!

[@Factory400]

This video is AWESOME!!!!! There are precisely ZERO experimental aircraft manufactures that present this level of information......many of them likely do not know themselves. 😍😍😍😍😍😍😍

[@jodyolivent8481]

So true.

[@michaelforseth8609]

It alsmosy seems like they are doing enough testing to get this aircraft certified one day.

[@chriskroeker1889]

They’re using the trial-and-error approach. Gotta love being a Guinea pig as a builder 😊

[@ParadigmUnkn0wn]

​@@michaelforseth8609 who would've thought... you know, that the requirements to design a safe airplane are also the same requirements for certification. Aviation rules and regulations have been written in blood through the years, and that includes the certification requirements. That said, I don't think an "experimental" Garmin G3X is any less safe than the one that costs 3x as much but comes with a sheet of paper saying it's "Certified." There are also tried and true kitplane designs like the Vans RV that have more examples flying than many certificated aircraft yet have a stellar safety record. The fact is that most kitplanes simply rely on being overbuilt and going quite slow. The big exception I can think of are the canard kit planes (e.g. Long-EZ, Velocity, etc.) but those are either Burt Rutan designs or copies of Rutan designs with enlarged cabins, and Burt Rutan took things like this into account. Scaled Composites (Burt Rutan's company) is still around and has built things like that crazy Stratolaunch twin-fuselage plane, a plane that flew around the world non-stop, the first pulse-detonation powered plane, and tons of other novel creations that have been quite successful.

[@spdcrzy]

@@michaelforseth8609 this is EXACTLY what they're doing. They fully intend for this to be a commercially rated aircraft one day.

[@bullittstarter4408]

There was so much information in that video i watched it twice. In flight school they teach you the basics or aerodynamics and tell you all the things not to do… this video demystifies the “why” so well! One of the best videos I’ve seen in a long time. Thanks for sharing!! A dark aero is part of my 10yr plan 👌

[@pejmanjavaheri9758]

All of these engineers at Darkaero are brilliant beyond genius! I can’t wait for the first flight video!

[@PandaStencils]

This is an excellent video, thank you for putting this together. As a structural engineer who has lived in the structural dynamics world of aircraft and spacecraft development projects for years, this is a great high level technical summary, with key concepts and first principals discussed in clear detail with great examples and diagrams. I can't wait to see this project fly.

[@jdannunzio64]

You are taking a very comprehensive professional approach. Much appreciated. And I actually understood everything bringing back memories from my undergrad engineering days as well as flight school aerodynamics!

[@earlgreystoke3324]

Top notch engineering! It has been a real pleasure watching methodical engineering approach your team has used to design, fabricate & test the Dark Aero. Well done!

[@stay_at_home_astronaut]

"There are two kinds of people that are afraid of flutter: those who don't understand it.... ....and those who do."

[@a10moondog1]

Phenomenally good explanation in less than 10 minutes As a pilot and non-practicing aero engineer I can really appreciate the complication involved with publishing a Vne speed. I'm certain that the Vne has a safety factor built in (200kts, 230mph for RV-7). All of you at Dark Aero are exceptionally professional with your design. Very impressive.

[@erikpnoman]

Fascinating description of flutter. As a musician, I am working with a simple plate, column of air or a string. You can see that in many respects that any object can be viewed as a complicated string with modes and/or nodes dispersed throughout the structure depending on stiffness, mass and frequency. The same exact elements are needed to describe a vibrating string. The last thing you want is to be flying around in a Tacoma Narrows bridge!

[@jhaedtler]

Kermit Weeks did similar test on his GB replica. An other great video explaining flutter problems! Thanks for the videos!

[@jonathanshirer2395]

Kermit found out, as I recall, that if he had flown it a little faster, it would have broken up. Probably saved his life.

[@paqx3534]

I'm in the first couple weeks of controls & stability right now- this video gave me a snapshot if where a lot of the building blocks are going! Good moto

[@nielsf2743]

You know tat someone really, really understands his stuff when he can explain the incredible complexities in simple English for dorks like me. Much Respect. Thank You!

[@zak_258]

I have an exam tomorrow in Aeroelasticity and KZbin by chance recommended me this video lol. Such an informative video! Can't wait to see that bird flying.

[@QuakeDragon]

Sam's explanations gave me the help I needed to understand design concepts that I've seriously been struggling to grasp. You have my gratitude, good sirs, for taking the time to record, cut and post this video!

[@willhibbardii2450]

Stellar presentation... Italian auto and aircraft designers employed construction methods with aluminum similar to what you guys have employed with DarkAero... It's interesting that a stallion constructed with carbon fiber of 1940s Italian style engineering is in the DarkAero stable... In the ladder logic of aircraft design observations of what works since computer analysis algorithms were verified by slide rule... It's incredible to witness vibrational modeling parameters transferred to the flat screen before moving forward with flight test. Time well spent in my book! Thank you for sharing 👏👏👏

[@troygiampietro9570]

Really good video. Gives a great overview of the concept with enough technical detail to get the point across.

[@carveroutdoors]

This was an awesome video and got into some aerodynamic engineering concepts that the average person (or pilot) had never encountered! Thank you!

[@dougostey]

Well done Sam and team DarkAero, it's great to see our former test intern pass on this knowledge. This is well done and is explains the science in a easy to understand manner.

[@DavePilotCH47]

Easy for you to say! LOL. I’m a former military helo pilot and the only thing I understood was vne! I think I just watched one of the smartest guys in the world👍🏻👍🏻

[@azzamaddas4437]

Superb video. I hope to see this Engineering feat gets the success that it deserves.

[@robertling9872]

Thanks for sharing this interesting video. It is special that you bring all these performance and safety topics together in one aircraft design.

[@vzmax]

Wow ! That was very interesting and informative, thank you ! When I was a student a few decades ago, I had several lessons on the "transformées de Fourier" and, of course, I forgot everything and never understood what it could be used for. Now I know !

[@blakechinn5792]

another reason why I am a happy reservation holder. Keep going ! truly revolutionary!

[@detonation5555]

It's amazing that you are making videos explaining this, thanks! I'm curious how good your frequency response was using a (small) instrumented hammer on such a thin structure, I've performed GVTs on large military transport aircraft and always used magnetic shakers that sweep in frequency to excite the structure with enough energy at low frequencies, I would generally only use an instrumented hammer for more monolithic structures like engine mounts. I guess you are working with the equipment you have available but adding a couple magnetic/rotating mass shakers into your test setup would for sure improve your results.

[@dougostey]

Kai, the hammer taps were likely done at the stiff points (spars and ribs). For small, linear structures, using impact hammers is a good method to get quality FRF. Larger structures, like a C-130 or 747 aircraft, require more excitation than can be applied with an impact hammer. That's where electro-dynamic shakers are used instead of hammers. We typically would use 6 to 12 shakers at one time on a large aircraft to excite all the modes at the same time.

[@psblad2667]

Very interesting! After seeing this I am still totally confused BUT on a much higher level!! 🙂

[@Mariano.Bernacki]

How a plane flies depends on its shape. Flying fast enough can cause the plane's shape to change. Depending on the strength of the structure, there are certain speeds at which a small change in shape creates a change in flying characteristics that tends to worsen the deformation. This can show up as vibrations that can be strong enough to damage the airplane, and/or changes to the shape of the airplane that impede safe flight. Therefore, these tests help them determine which speeds to avoid to keep the airplane safe and sound.

[@psblad2667]

@@Mariano.Bernacki Thanks! What puzzles me is how you can determine how the airfoil will react in flight from making vibrations. I have seen wind tunnel test (like the ones shown in the video). I find these vibration test amazing.

[@jamescrud]

@@psblad2667 Much of this "testing" was already done in software like ANSYS before finalizing the design airframe components. My guess is at this point they're doing real word testing so they can confirm the results from the software analysis.

[@dougostey]

@@jamescrud This is mostly correct. There are computer models (finite element models) of the aircraft that are used to predict when or where flight instability occurs. The ground vibration test (GVT) is used to measure the mass, stiffness, and damping properties by measuring the natural frequencies and mode shapes. The test results are then used to update the computer models to match the test results. Once the computer model matches the ground test, then you have more confidence in the model predictions.

[@markbutler4040]

That was one of the very best explanations of a very complex phenomena. This continues a theme of this project; displaying an excellent understanding of the finest points of engineering using very fundamental principles. I can think of no better road to success.

[@Ender_Wiggin]

wow, that was one of the most clear and concise explications of a complexs topic I have ever seen.

[@michaelhurst506]

Great presentation on the rationale, means, and set-up for ground-based flutter testing! Love the precision and comprehensiveness of all of your work on both the aircraft and your videos. Thanks.

[@rustlerboi1052]

This is awesome stuff, guys. Really respect the DarkAero team for this. I don't think there's any other company out there that's producing content like this, while also developing a great product.

[@greghart6310]

Cheers guys! That was a clear and concise explanation of a complex phenomenon that even a luddite such as myself could understand. All the best - can't wait to see this beauty take to the skies!

[@scubasleeve3497]

I admit I didn't understand a good portion of that, but what I do know is the DA team is being extremely thorough in the design and testing on this aircraft! Very cool!

[@billl7551]

Excellent basics explanation for aeroelastic dynamics. I hope as you progress more will be shown of the exciters and mode shapes. I am quite interested in the mechanics of software, instrumentation, and data collection necessary to do this on an experimental aircraft. Keep up the good work and darned impressive team you have tapped and assembled for this project. Continued appreciation to all involved in the project. Well done . . .

[@Mariano.Bernacki]

I cannot speak for the business side of your venture but I am beyond impressed by your engineering. I am confident the DA1 will meet or exceed all requirements.

[@tcoradeschi]

It’s been something like 40 years since my undergrad dynamic systems classes (Prof Ira Cochin for those who may recognize the name). You brought back some memories!

[@kevinhornbuckle]

This is a good study for wind instrumentalists. The tongue is the airframe with which to control the wind so that the horn manifests frequencies in certain artistic ways.

[@markzieg3593]

Talk about a cliff hanger!!! Can’t wait to hear what kind of VNE you’re going to have with dark aero. Sam did a really great job on today’s installment

[@markcrane6959]

this is beyond awesome - an absolutely mad geek out , you guys are bringing your A game more and more !

[@MrMoeRod]

That was a great description of modes, not an easy topic, Bravo!

[@ashsmitty2244]

I agree with many of the comments. This was nerdtastic! “Flying into flutter” is very interesting to me.

[@braincraven]

Thank you Sam for explaining the importance of good engineering testing for airplanes. This is well appreciated.

[@JackLangenkamp]

Wow, awesome video you guys! I really enjoyed the deep dive into this technical aspect of the design and construction. Keep up the great work, can't wait to see it in the air!

[@Mr_ASIC]

I wish you the best of luck , you are a living example of commitment

[@mahatmadoo2566]

Your presentation was really well done. Love the research that you are doing!

[@phantomhck]

Great breakdown, love to see nuances and finer points of engineering explored

[@pbjtime321]

I was wondering what the VNE speed was going to be. Especially with the turbo version of the UL520 coming out after you already started developing this plane I’m guessing at 15,000 feet at 220 hp it would absolutely scream through the skies.

[@ashsmitty2244]

Wait till I tell them I’m thinking of an Allison 450hp That’ll give them a heart attack. 😅

[@ashsmitty2244]

Also, with most recip prop aircraft VNE is engine RPM exceeding limits before anything else. ☮️

[@johnlichtenstein6158]

@@ashsmitty2244 this is why you have a constant speed prop

[@ashsmitty2244]

@@johnlichtenstein6158 That definitely helps. A reversible prop would be fun, lol.

[@keithjurena9319]

@@ashsmitty2244 Some turboprop engine/prop combos have a beta range which is exactly that. Turbines are strange..on startup, turning the fuel on can cause turbine inlet temperature to rise past limits so the prop is put into feather position to dissipate energy from the power take off turbine which helps the gas generator turbine get more mass flow into the process to cool turbine inlet temperature.

[@yehuda.r]

I thoroughly enjoyed this explanation. Thank you!

[@RM-el3gw]

Greatly appreciate these educational videos, keep it up! Hope you guys will be in the air soon!

[@StephenSemmelrothTeamHappyDay]

Really great intro to Fourier transforms and why they are important!

[@BrotheuZ]

Awesome work as usual 😎 When are we getting more information about the Vne ?

[@mikegofton1]

Love the engineering excellence on display in DA. Any plans to instrument the airframe for strain during flight tests ?

[@dcplunkett]

Interesting. Looking forward to something similar for the flutter testing.

[@paulbrouyere1735]

How nice to see how you guys are evolving. This really is the 21st century. And I’m still modeling paper models for a vertical axis windturbine😁

[@WingsNSails]

This is the coolest video I’ve ever seen

[@neumeisteranimalhospital2627]

I liked it, even though I had no idea what you're talking about. :)

[@EJWash57]

Wait. I was able to keep up with the presentation! Sam really knows how to push this out in plain (plane?) language.

[@christopherbeddoe406]

Brings back memories of Mechanical Vibrations course from college. Apply all this to an Airplane would be very cool.

[@Arthur-qo3rz]

Wow! I really enjoyed this video. Just awesome.

[@RealBobStovall]

The most fascinating video of this entire project. I've always wondered how aircraft designers determined VNE and, by virtue of this video, I have a better understanding of the process. Any plans to test a full-scale aircraft to destruction in, say, a wind tunnel, to verify/validate your calculations?

[@vandalMav]

excellent stuff gents--keep up the great work and thx for producing the content

[@VanWarren]

these are fantastic videos for aerospace engineering.

[@leslienordman8718]

Super: thank you for talking about this. Is it possible for you to add even more graphics to this episode to further explain things: Your friend really knows his stuff, but all the rapid-fire introduction of all the technical terms made this very important episode hard to follow, especially for those of us who have not had to deal with this before.

[@jakarta26]

Very nice work. Looking forward to seeing were your "factory" Vne falls.

[@ailijic]

Best episode ever, thank you

[@11Sparky111]

Incredible. Model based engineering is truly a thing to behold.

[@capnthepeafarmer]

This is kind of funny how similar this vibration analysis is to every other vibration analysis. I used the same workflow for vibration analysis of cutting tools in specific machines. However the goal in machine tools is to stay in a stable cutting parameters all the time, or right at the limit for maximum material removal.

[@suburbangorilla5515]

Impressive professional approach to a safer first flight! Bravo.

[@cmmguy99]

That guy was straight out of Big Bang... excellent video.

[@motoguzzi7592]

Are there plans to put tie down points on the aircraft?

[@lornes7526]

Would the aquired data be relevant if keeping the overall shape of the aircraft, but increasing it's size in the future to accommodate additional seating, or is it airframe specific?

[@NeilStainton]

I love the way you lie guys do this so professionally and thoroughly. I’m learning a lot. Thank you.

[@felixaudet5860]

Thanks for posting. I think YT should automatically monetize content like this. You deserve it.

[@endokrin7897]

I wish you guys the best. Hopefully we'll see a true four seater twin one day from Dark Aero. 👍

[@iuppiterzeus9663]

great explanation !

[@christiancattell8257]

Great video! I wish you guys the bedt of luck

[@Maynardtkrebs]

Nice descriptions. Thanks!

[@WymansWorkshop]

Very interesting video. Enjoyed that

[@ericsandberg3167]

This was a great presentation on modal analysis and how it is used in the study of aeroelasticity. I would be curious to know how this carbon fiber structure is in regards to damping and if you guys are going to have to install trim weights or stiffening structures in strategic locations to tweak the modes.

[@rfourie]

Excellent explanation!

[@stephenwhite5444]

This is some top shelf engineering!

[@yashmanwani6232]

Studied all of this in 'control systems" engineering class. Though never applied the concepts to airframes. Is there a specific course or class in aeronautical engineering to apply these "control systems" concepts to airframes?

[@zakiabdinasiromar5434]

Yes, I also remember this in my control and instrumentation module.

[@mully006]

Are you going to check for control serface reversal as well? I remember this also coming up in my aeroelasticity course.

[@alexlo7708]

Hammer shock input made an inpulse response of the airframe from anywhere sensors attached. I think it has fomula in convolute all these impusle reponse to become a model response system.

[@edmondthompson1523]

Great episode. Loved it. Thanks.

[@jbrownson]

Great explanation, thanks!

[@pedrorivera7610]

So close! Keep it up gents!

[@DustyLambert]

Hey you actually made a video on it after I asked, haha, thanks guys, you rock!

[@clarencehopkins7832]

Excellent stuff bro

[@mybigredtruck2000]

Hi Friends, Thank you for the great explanation, I actually understand what you are doing

[@ericbergdahl6971]

Thank you for sharing that with us.

[@himanshuanand9048]

Sam literally condensed a sea of information into a tea cup. Kudos man!

[@metaltradesolutionsllc5274]

Wonderful Video! I learned a lot! Thanks!

[@acengineer737]

Very interesting guys 👍🏻

[@Mrsournotes]

Excellent presentation.👍🏽👍🏽

[@DanielMsanii]

It's humbling to learn just how much of engineering goes into the design. Laypeople like us probably know only a drop-in-the-ocean amount of what the actual aerodynamics entails.

[@tommyboy054]

This. Is. Fascinating.

[@palletcolorato]

Good stuff guys! A little over my head though.