The engineering required to fly fast (GVT)
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- čas přidán 14. 07. 2024
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We have been working on ground vibration testing the DarkAero 1 prototype. The objective of this effort is to characterize the vibration mode shapes, natural frequencies, and damping of the airframe. This will help us build a model of the aircraft to predict flutter speeds and ultimately the Vne or never exceed speed of the airplane.
0:00 - Intro
0:52 - Sam Jaeger
1:05 - What is Aeroelasticity?
1:36 - Aeroelasticity Fundamentals
2:54 - Degrees of Freedom & Modes
3:51 - Divergence
4:58 - Flutter
6:45 - Ground Vibration Testing (GVT)
9:25 - Next Steps
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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.
Exactly! It was very pleasing to listen to the explanations.
Special thank you to Mike Sracic PhD for your support and technical guidance on the ground vibration testing!
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?
Suggest checking into phenomena of “rudder lock” which affects high aspect ratio fins/rudders.
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.
😍😍😍😍😍😍😍
So true.
It alsmosy seems like they are doing enough testing to get this aircraft certified one day.
They’re using the trial-and-error approach. Gotta love being a Guinea pig as a builder 😊
@@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.
@@michaelforseth8609 this is EXACTLY what they're doing. They fully intend for this to be a commercially rated aircraft one day.
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!!
That’s awesome! Really happy to hear you found value in the video. :)
Dude if your expensive college education can’t get the point across yet a guy on CZcams can, This should be evidence of the college ruse debt scam
University provide order in study. Even if we can reach certain information, it doesn't necessarily mean we can learn without guide.
@@carbonEYE007the 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.
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!!!!
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 :)
I have an exam tomorrow in Aeroelasticity and CZcams by chance recommended me this video lol. Such an informative video! Can't wait to see that bird flying.
Very interesting! After seeing this I am still totally confused BUT on a much higher level!! 🙂
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.
@@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.
@@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.
@@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.
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 👌
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!
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!
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!
Kermit Weeks did similar test on his GB replica. An other great video explaining flutter problems! Thanks for the videos!
Kermit found out, as I recall, that if he had flown it a little faster, it would have broken up. Probably saved his life.
Really good video. Gives a great overview of the concept with enough technical detail to get the point across.
another reason why I am a happy reservation holder. Keep going ! truly revolutionary!
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.
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!
I thoroughly enjoyed this explanation. Thank you!
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.
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
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.
Thanks for sharing this interesting video. It is special that you bring all these performance and safety topics together in one aircraft design.
Superb video. I hope to see this Engineering feat gets the success that it deserves.
Nice descriptions. Thanks!
This was an awesome video and got into some aerodynamic engineering concepts that the average person (or pilot) had never encountered! Thank you!
Greatly appreciate these educational videos, keep it up! Hope you guys will be in the air soon!
Wow! I really enjoyed this video. Just awesome.
Your presentation was really well done. Love the research that you are doing!
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.
excellent stuff gents--keep up the great work and thx for producing the content
this is beyond awesome - an absolutely mad geek out , you guys are bringing your A game more and more !
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.
Best episode ever, thank you
Great breakdown, love to see nuances and finer points of engineering explored
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.
Great video! I wish you guys the bedt of luck
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 !
I liked it, even though I had no idea what you're talking about. :)
Great explanation, thanks!
wow, that was one of the most clear and concise explications of a complexs topic I have ever seen.
That was a great description of modes, not an easy topic, Bravo!
Excellent explanation!
Very interesting video. Enjoyed that
Great episode. Loved it. Thanks.
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!
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!
Great content!
This is the coolest video I’ve ever seen
these are fantastic videos for aerospace engineering.
That guy was straight out of Big Bang... excellent video.
Fascinating!
I agree with many of the comments. This was nerdtastic!
“Flying into flutter” is very interesting to me.
Interesting. Looking forward to something similar for the flutter testing.
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!
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.
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👍🏻👍🏻
great explanation !
Thank you for sharing that with us.
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!
Excellent stuff bro
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 . . .
I wish you the best of luck , you are a living example of commitment
Very interesting guys 👍🏻
Very good!
Wonderful Video! I learned a lot! Thanks!
Impressive professional approach to a safer first flight! Bravo.
Awesome stuff!
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 👏👏👏
Awesome work as usual 😎 When are we getting more information about the Vne ?
love this
Excellent presentation.👍🏽👍🏽
Brings back memories of Mechanical Vibrations course from college.
Apply all this to an Airplane would be very cool.
Thank you Sam for explaining the importance of good engineering testing for airplanes. This is well appreciated.
This. Is. Fascinating.
Really great intro to Fourier transforms and why they are important!
Very nice work. Looking forward to seeing were your "factory" Vne falls.
This is some top shelf engineering!
Hi Friends, Thank you for the great explanation, I actually understand what you are doing
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😁
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
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!
Love the engineering excellence on display in DA. Any plans to instrument the airframe for strain during flight tests ?
Very informative ..thank you
nice job
Very informative!
The spring equation bright back memories...
Good stuff guys! A little over my head though.
Very nice
Very educational.
So close! Keep it up gents!
Very cool
Incredible. Model based engineering is truly a thing to behold.
it looks pretty good
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.
I wish you guys the best. Hopefully we'll see a true four seater twin one day from Dark Aero. 👍
We wanna see it fly!!
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.
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.
Wait. I was able to keep up with the presentation! Sam really knows how to push this out in plain (plane?) language.
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.
"There are two kinds of people that are afraid of flutter: those who don't understand it.... ....and those who do."
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.