EVTOL Propellers complete guide
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- Опубликовано: 23 апр 2023
- In this video we look at all the basic information that one needs to know about propellers. Adapted Ducted fans and toroidal propellers are covered
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Guys how do you like long format video? Do you think its a bit too much information?
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Its good information. Not too much here. Thank you and congrats on getting your sponsor.
@@RobShuttleworth Thanks for your feedback
Yeah I like your videos for the detail and explanation of principles and design, as well as keeping us posted on the state of the industry and individual companies and the progress of their models. So please don't dumb it down for length; I like to know what you know! It's been great so far, this is my primary and favorite aviation channel, especially since it's electric aviation centered.
@@justinklenk Noted
@@ElectricAviation A review of any simulation software will be appreciated. It looks fascinating ruclips.net/video/0au2IA4uUok/видео.html
Love your Channel. The clear and precise way you explain concepts and consequences is joy to listen. Thanks
Thank you. Your appreciation is the tonic for my encouragement
I love his informative videos too. I used to "learn and listen" to his channel while I went jogging but because of the long double commerical breaks in the middle of all his videos. Unless the viewer stops what their doing to click SKIP, those 2 ads run for 3 and 4 minutes respectively
I appreciate how you explain things in simple terms that a lay person can easily understand.
Thank you very much for your editing and effort.
Tip speed in ducted fans isn't limited to Mach 1. Turbofans commonly operate at 1.1 to 1.3 mach tangential tip speed. The duct regulates axial flow speed to approximate the pitch speed of the fan, which keeps blade AoA low and reduces wave drag. Excess or insufficient flow is handled at the inlet rather than the blade as the inlet spills or sucks additional air to make the duct velocity suitable for the fan pitch.
This is excellent. Perfect for reference material. For those of us who are not mechanical engineers, Thank you.
I love your work it's always exciting to see a new video of yours come out.
Thanks for your excellent work. ❤
Very good. Thank you very much! These principles considered from opposite point of view = optimized wind generators. I have to watch all your videos. Cheers!
Great summary, thank you!
The best videos on evtols,keep it up 🎉
Thanks
thank you very much! It was very informative
thx for the video, it really helped me clear some questions i had kk
Thank you my dear friend! Your video presentations and knowledge are PRICELESS!!
Thank you kindly!
I learned a lot!
🙋♂️THANK YOU FOR SHARING THIS ℹ️ WITH US 💚💚💚
What a great information how propellers work and thank you for sharing it.
Glad it was helpful
I would like to know more about noise reducing systems in V-tol. Great channel 👍
Awesome, very interesting
amazing, im very interesting into the toroidal propelers, although there is another company that used the conventional propelor models and achieved very low noises for drones, so much to see yet. Greats video!
cool, seems lately there are so much new innovation for propellers
Good stuff. my propeller is still an undiscovered gem.
you got yourself a new subscriber.video is awesome
Thanks for subbing
Hi this is Wilber and my brother Oroville said I should check out your video and I think it is great and it's giving me some good ideas for a Moon Ship I'm trying to build thanks... 🌙
There is also the asymmetric propeller from Zipline.
Apparently quite = efficient.
Amazing
Absolutely AWESOME! I have been searching a long time for vids on prop theory & design. This vid covered many of the topics relevant to prob efficiency & efficacy. I would love if you'd make more on this topic focusing on some of the techniques, e.g. ducted w/ high blade count, etc. While I'm blabbing my wish list, a little more detail on the fluid mechanics (e.g. compressibility) would be nice, too.
Anyway, thanks for the time & effort I knew it took to make this & keep 'em coming!
Glad it was helpful!
Correction at 4:28, For hovering we need lower pitch and for forward flight we need higher pitch. Great video anyways.
My apologies
Great video, and pleased to see your hard work is getting sponsorship. My initial thought is that one of the most important modes of flight is performance after power failure. This has driven fixed wings to think deep about takeoff procedures, and has driven helicopters to think deep about disk loading for autorotation. The argument in e-VTOL is that multiple redundant electric systems will lead to >1E9 hrs to failure. This has lead to many e-VTOL designs with high disk loading and no autorotation capability (for example rpm control thrust in place of collective control thrust). However, the certification authorities are yet to agree to this approach as they know that even 1E9hrs standards can and do lead to incidents. So EDF is perfect for e-STOL, but we are likely to see a drive towards larger Q-tip blades for e-VTOL.
And, don't get me started about the design depending on ballistic recover systems to recover a total/cascade power failure near the ground during landing.😖 I will simply quote the Zefhir helicopter website "If you can, autorotate. But if you can’t, the parachute will save your life!"...
One thing Skyfly Axe got me interested in was its better glide ratio. One of the few aircrafts that can glide in case of a power failure. I like the Antanov AN2 for the same reason. The aircraft doesnt have a stall speed. These are the designs that should be electrified
@@ElectricAviation , a good glide ratio definitely helps, although technically this means the failsafe operation is STOL and not VTOL. Whenever I see drones clatter to the ground after battery failure I always think that it was a good thing that it wasn't capable of carrying passengers.
The best example about why VTOL needs autorotation is the AW609 tiltrotor, developed from the V-22 Osprey, that 20 years on still hasn't passed certification. The original V-22 concept was developed without autorotation in mind, but the high disk loading has led to some nasty vortex ring state accidents. The AW609 can autorotate, at very high descent rates, but not sure this has been demonstrated to full landing yet.
Jaunt Air Mobility certification is expected in 2027, so I guess this is the line in the sand for all of the high disk loading e-VTOLs out there...
@@martingarrish4082 True. STOL is the way forward in the near future
I'm really tired of this autorotation argument, when does *only* the turbine or engine on a heli *exclusively* fail?? Probably 1 in a 1,000, the engine is by far the vastly most mechanically reliable component on at heli, if it's anything *BUT* the engine going haywire you are seriously screwed, that's why after seeing dozens of helis go down - on video, I've yet to see even one employ this almost mythical 'autorotation' technique to save itself.
Better to rely on multiple ballistic chutes (like whole craft ejection seats) and enlarged ground proximity/approach velocity sensor equip airbag systems to ensure survival.
Same deal with gliding to the ground in a fixed wing personal craft, the Earth isn't a uniform lush golf course green ready to give you a safe crash landing, the same solution applies chutes and airbags.
@@Veldtian1 , I'm not against any of the safety systems you mention. Ground impact airbags actually make sense. In fact, I'd like to see rotor RPM governors implemented on helicopter collective pitch levers to ensure autorotation entry. But what does bother me is that lots of e-VTOL designers are using these systems to just ignore the basic physics of hovering flight.
Anyway what we think is irrelevant because it will be certification authorities that decide what flight envelope to impose on an e-VTOL design. If the strategy selected so much as sneezes about flight safety they will have no compunction about grounding the fleet either. So we do need to have the discussion - ideally 10 years ago...
You've inspired me to yet another idea.
I was watching an anime, where one of the factions had power armor. The mobility was provided by powered roller blades, and jet engines.
And I thought that's not really a bad idea.
Skip the power armor, use powered roller blades, and instead of jets, electric motors mounted bi-copter style on a backpack.
Not enough for full flight, but enough to do some epic jumps one or two stories up, and theoretically provide enough downforce to skate a vertical wall.
Also it would work like a steerable electric parachute.
You don't have to sustain flight to get most of the advantages of flying around.
User interface is definitely going to need some AI, and possibly brain interface. Good thing both of those technologies are off-the-shelf now.
Do you have a source for saying that most of the gains comes from the inlet/ outlet rather than the tip vortices vanishing?
4:38 yep 👍 have VP - Variable Pitch in my logbook 😎
I love this! Very easy to digest! Sir, I am developing a racing eVTOL for a thesis and I need to do some research for the whole references and the stuff I need to write to have a background of the calculations I'll make. By any chance do you still have some examples of where you got all this information?
Great work! Thanks in advance
As mentioned in the video, ducts eliminate the tip vortices and improve safety in the vicinity, but add weight and cross-section; the latter can cause the aircraft to be adversely affected by cross-winds.
Toroidal propellers greatly reduce (nearly eliminate) the tip vortices and improve safety in the vicinity (not as much as ducts, for either of those) but don't add significantly to the cross-section and add less weight than a duct.
Makes me wonder if anyone is working on an e-VTOL with contra-rotating toroidal propellers. And if not, why not? I would think it wouldn't be too difficult to add toroidal props to the Jetson ONE, assuming one had a way to manufacture such things.
I think the jury is still out on the toroidal props. One thing that can be said with certainty about them is the lower noise. There are a lot of configurations that need to be checked with them before they can be used in Jetson one.
The good thing is drone enthusiasts are testing them and so far like what they have seen in terms of performance.
bUUUUTTTT, ducts can be turned into mini ring wings. as a thought.
You got high and low pitch mixed up a bit. One example at 4:30. Low pitch is like first gear…more acceleration but less top speed.
easy mistake to make. I get things backwards all the time, since my brain surgery.
I feel the design should make use of the tip vortex, making it an impeller, which creates a vacuum where the vortex flows in and out of.
Making the blade like a ice-cream scooper. round side pushes the air to the side (pressure) while the hollow inside creates the vacuum, which is much stronger then the pressure, creating a stronger inflow.
this inflow then should be guided.
There is another even more futuristic propeller/thrust technology that I have not seen yet and that’s putting the electric ‘engine’ into the duct so that the blade tips are at the centre. In underwater props these systems are called ‘rim thrusters’. The ducted fan axial flux motor air rim thruster…
As a fellow admirer of the Cartercopter I was hoping you would look at their scimitar propeller. It seems to have attractive advantages and fewer downsides than many designs. I am also intrigued by helicopter four blade tail rotors with the blades paired to form a narrow V shape. It was reported to be unusually quiet. Any idea why? Noise is the biggest problem with the widespread adoption of electric aviation. IMO it should be prioritised as high as any other facet of propeller design.
Thanks for the suggestion
What if you could spin each blade so the air is pulled inwards while the whole propeller rotates for forward thrust. Would it create more focused forward thrust and reduce drag from each blade?
Just for fun, how about adding a pin wheel fan in cruise mode connected to a generator to charge the battery? (Sort of like regenerative braking in cars? Very informative video. It helps to figure out all the new designs I've seen.
Any fan will create drag, that will need to be overcome by the main propellers. And the energy gathered will be less then extra energy spent. Having said that there are regenerative mechanisms in a few eVTOLs. The capture the energy and recharge the battery during decent
This would be great as an interactive course....
2:43, is that because the blade tips generate vortecies which produce drag, thereby making it harder to propel? If true, then wouldn't it be prudent to research how to reduce tip vortecies?
I'd say the Custer Channel Wing deserves reasessment, but with some modifications, propeller running on leading edge of channel, if having it on thicker part of airfoil or elsewhere is to be experimentally determined, also if a counter-propeller, fixed vanes after propeller, changing swirl flow from propeller into a linear flow would improve efficiency. Antonov Izdelye tested the channel wing with propeller in leading edge, they say with some tethered flights, but soviet system crisis discontinued research.
Blessings +
😎👍🏼....now try this with boat props. 😉😂
They are generally about a decade behind but they have discovered toroidal props..
Instead of using the propellers moving in circular path, if we are able to design the propeller blades to move in eleptic path with the major axis of the ellipse is parallel to the wing of the plane, (or even in a path similar to the toroidal path) we may get better results.
For any VTOL machine, a good choice would be having some gliding ability in case of power failure.
A single 6.5ft diameter Adaptive Ducted Fan (ADF) is capable to produce 6000lb thrust consuming 1MW power and propel over 400knts cruise speed.
Is there any common metric for measuring noise levels from EVTOL's and other aircraft. I wonder how much data there is out there to compare the various vendors. I would love to see just how quiet the Lilium really is.
You mean other than decibels?
Lilium is noisier than most eVTOLs but quieter than EDF powered aircraft
lets see if lilum survives this summer.
more cash needed.
im very curious as the lilium team doesnt look too anxious to the future.
maybe theyre already pretty far into negotiations for financier.
would be sad to see this unique design fail by running out of money a year before building the actual aircraft meant to achieve certification.
I like to see a tongue type thrust vectoring concept
you'd need more than a 3 axis CNC mill, since there are significant undercuts. 5 axis is likely what you meant. (8:25)
5 Axis is what I meant. Cheers.
supersonic is not mach 0.8 but mach 1= 1234km/h, so all passenger aircrafts (except the Concorde) are SUBSONIC (speed to air not to ground who depend from the wind).The propellers from the TU95 are subsonic (and turn very slow), the only known plane who had a supersonic propeller was the incredibly noisy Republic XF84H Thunderscreech but the airspeed of this plane turned out to be disappointing and not better than that of the Tu95
2:40 so why plane Jet engine have so many blades
Unducted fans maybe the future as they can travel at transonic speeds with the efficiency of a turboprop
What craft is shown at 7:32?
Plana Aero
@@ElectricAviation little bit similar to the Hummingbird I submitted to your competition last year.
Propeller with duct or cowling don't have much more benefit unto it,infact it will just only reduce the effecience of propeller because of surface friction in low rpm and that will cause a stall and especially the tip of the propeller are not fit to adopt the environment which the forces of air is very different ,I hope someone get it.😅 While a ducted fan with a wide fan tip will have more gain to it's thrust by also from exhaust stator guide vanes (if) the stator guide vanes was tilted on different position like on co-axial setting by producing a higher pressure compare to stator guide vanes that is just only function is to straighten the air flow, the stator guide vanes tilting at a different position may also secure the possibilities of so called (compressor stall) or just limit a some of air to push back to the intake duct because of a exhaust convergent design.
0:10 "Co-rotating coaxial propellers" do not exist in practice.
0:48 "Thurst" = thrust.
3:43 High pitch angle at the root to low pitch angle at the tip.
7:44 Most designs use tilting rotors for vertical takeoff and cruise, so require variable pitch propellers for better efficiency.
8:41 Sharrow propellers are manufactured on 5-axis Heller HF3500 CNC machines.
8:52 Worse control due to poor PID response from the greater mass/inertia of the toroidal props.
9:01 Jetson ONE does not use coaxial propellers; rather, each corner uses twin motors in a tractor-pusher configuration.
9:14 Coaxial propellers/rotors provide more control and maneuverability for the same footprint as a single rotor; however, two separate rotors are more efficient and provide more thrust/control.
9:20 Jetson ONE has fixed pitch propellers/rotors, so cannot vary the pitch of each rotor; likewise, each corner's pair of motors vary their rotational speed together.
9:29 Contra-rotating coaxial propellers can be arranged such that the aft propeller is smaller in diameter but higher in pitch than the fore propeller, which could provide better efficiency than a single propeller. (Similar to the ducted fan, albeit variable pitch, discussed at 15:15.)
9:40 "Co-rotating coaxial propellers" do not exist in practice.
9:52 "Co-rotating coaxial propellers" are not used in practice, as opposed to contra-rotating coaxial propellers, because of the lack of cancellation of torque/propwash/gyroscopic precession/etc., more susceptible to lateral wind gusts, and way less efficient given that the aft propeller blades are constantly traveling in the turbulent wake of the fore propeller blades.
🔶Our infinitely variable FrictionLess gear tech enables >10X gear box reduction‼ Non-coaxial contra architecture is possible. How? I'm a triple engineer. We will also bring out an efficient, clean, noise-less, ultra power dense rotary engine what will use any fuel or mixture thereof 😉🧐 🔶
From what I've gathered ducting is good for high trust at low speed, you can try to fix the problems with the ducts increasing drag with ultra complicated duct designs, but the problem is fundamental, and absurd complexity is huge disadvantage in aviation. The issue of ducting or not is very well understood, in high speeds, open propellers are best choice essentially as long as the speed isn't over what the propellers are good for. This is shown by when turboprops are chosen, over turbofans and vice versa. It's not a new issue, no need to reinvent the wheel there. Another example is the water propellers, most are open design, but there are exceptions, ducted propellers are common when high thrust is required at low speeds, like on tugboats, and also when high thrust is required in a very small space, you can use pump-jets. Pump-jets are technically less efficient than open propellers at high speed, at least until the open propellers run in to their limitations.
Contra-rotating coaxial propellers can improve efficiency, because the second propeller can turn rotational flow into thrust. That's a widely known and accepted fact. The main disadvantages is the increased complexity, which introduce a number of issues, and the fact that they tend to be noisy. With electric motors it's quite easy to just use individual motors for each propeller, like on the Jetson one. Using individual electric motors essentially solves complexity issue, and the disadvantages of dividing the power over more motors is insignificant compared to doubling the number of combustion engines for the same output.
Together with some other potential advantages of electric motors, over combustion engines, and aerodynamic advantages with a single axle dual rotor over a larger number of smaller propellers it's likely electric helicopters with contra-rotating rotors will be "the" choice for EVTOL. At least for moderate speeds and distances, like up to a few 100 km/h speed and a maybe up to 100 km distance. To maximize efficiency you want the lowest number of blades, that means the lowest number of propellers, or rotors, as other aspects practically allow, except for contra-rotating because of the rotation to thrust benefit. That is, of course assuming no duct, and ducts aren't worth it as the limitations of propellers/rotors is reached.
Even for unmanned multirotors, where even styrofoam ducts with negligible weight could be used without risking anyone's life they have'nt been able to improve efficiency, ducts are rarely used despite they could make multirotors much safer and reduce noise significantly. So, despite potential huge benefits, and no significant difficulties, ducts are generally not considered worth it, except for toys when safety is way more important than efficiency, and or to make them look cool. So, "in theory", sure, but in reality, open propellers/rotors are more efficient.
Lilium seems to struggle to achieve manned flight at all with ducted fans, according to wikipedia they have existed since 2015, and has 800+ employees. At the same time multiple amateurs have made manned EVTOLs in a fraction of that time, using a fraction of the resources Lilium spends per hour, using open propellers. That should give a clue about ducted fans vs open propellers, and even tell more about the probability that Lilium is going to make a production model, ever. As of now their latest demonstrator is possibly the most expensive drone in the world. When a company only produce demonstrators, and cgi, for a number of years, the company is probably an endless money pit.
Ducts can reduce penalty of using many small propellers/fans, compared to bigger propellers/fans with ducts, but they are not as efficient as open propellers.
That brings us to "toroidal" propellers, which are kind of a bad compromise between ducted and open, with the duct-equivalent part on the propeller. They can absolutely be more efficient than *some* conventional propellers, but they can absolutely not be even as efficient as the most efficient conventional propeller for the task. Basic understanding of aerodynamics and/or comparing to a well chosen conventional propeller will tell you there's absolutely no reasonable doubt about this. Also, if you want high efficiency over a wide variety of speed and or thrust, you need variable pitch, it would be extremely difficult implement in a good way with "toroidal" propellers.
So, in summary, conventional open propellers are the most efficient choice, in the range of thrust and speed where they are good. When it comes to speed look at turboprop vs turbofan for an indication when ducts becomes advantageous because of speed. If the "right size" of open propeller is too big, ducts can increase efficiency, compared to push a small propeller beyond the range where it is efficient, so ducted fans can be more efficient, if compared to an open propeller that is too small for the specific application.
Then there's the issue of variable pitch, perhaps not as near impossible to implement with good results as on toroidal propellers, but still near impossible. It's not used on turbofans, they're design to be efficient within a limited range of speed and thrust, you can't practically achieve variable pitch and stack the blades like that, and reducing the number of blades to achieve variable pitch would reduce thrust a lot all else equal.
To some degree this is an issue for EVTOL, how much sacrifice is it worth to achieve high efficiency in other than cruise mode? I mean, is the idea that they should be able to be stuck in traffic for long periods of time? It's required to be able to take off, hover and land vertically, but the efficiency doesn't have to be very high unless it's supposed to spend a lot of time taking off, hovering and landing. If the idea is to spend a lot of time non-cruising, well, then the basic design of an helicopter is probably by far the best bet. If 90+% of the energy is going to be spent fighting gravity anyway, it's just not worth a lot of added complexity and or weight to maybe reduce the remaining sub 10% a little bit. If you want to be able to travel very far and very fast on battery power, maybe you have to accept you wont also be able to take off from any roof in the same thing anytime soon. Flying fast and far on battery power even without VTOL capabilities is yet to be achieved. Adding VTOL requirement doesn't make being able to go fast and have long range easier.
BTW - it's "Sabrewing" - not "Saber". This video is copyrighted, by the way.
Check 3:40-:55. You contradict yourself and say exactly the opposite low/high in a few seconds...
AeroWheel Goodyear open Expectatives on VTOL Aplications ruclips.net/video/XnuGCjITCzg/видео.html - as Pragmatic reference, a Scale Model can Display real posibilities, starting with a Canopy-Aerodinamic Cockpit-Pod Velomobil in 3 TryBike Dual Mod - Wheel + Propel.
Any idea about this type of ducted fan 👇👇👇
ruclips.net/video/B9EY_cMx_7Q/видео.html
you forgot one: flutter flag drive fan, flex only
yes ducted (or not)
also plasma ion railgun candle ionic wind drive jet thruster, yes ducted
propellers are so 40s, same for jet engines
anything not solid state or near solid state is old trash tech, stone age thrusters
law of why to do that old jank