Another commercial electric airplane

Discussion in 'Hangar Flying' started by blane.c, Jun 21, 2019.

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  1. Jun 21, 2019 #1

    blane.c

    blane.c

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  2. Jun 22, 2019 #2

    PTAirco

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    I would like to hear the company explain why they decided to make this a taildragger. Or why they put the engines near the wingtips. Other than "it looks cool".
     
  3. Jun 22, 2019 #3

    Dan Thomas

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    Exactly (except I don't think it looks cool). A taildragger in a world where taildragger pilots are rare. The flat ground attitude means a liftoff speed far above stall, lengthening takeoff roll enormously. Propellers on wingtips where any bank at all during takeoff or landing, in the process of dealing with a crosswind, destroys the prop when it touches the runway. And any failure of a wingtip motor, motor controller or propeller means that the other must also be shut down to prevent total loss of control due to the huge assymetric thrust. Even a big enough bird would bust a propeller.

    Looks to me like it was designed by some non-pilots.
     
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  4. Jun 22, 2019 #4

    TerryM76

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  5. Jun 22, 2019 #5

    Derswede

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    Think that is a DBMBA design. Such designs are common esp whenever someone throws money at a project. They come out in droves.

    Designed by MBA. Their idea of "It will fly" has nothing to do with aeronautics. Only applies to making money.

    I had several major products totally ruined by MBAENGINEERING. When an MBA took over the engineering design group, about half of the team fled. The rest took the blame when the project went overbudget, ended up not acceptable to the customer, or was just plain stupid and poorly thought out. (example, a gas pump which could accept up to $100 bills...after a long holiday weekend, when fuel was at nose bleed prices, several of the pumps disappeared...the drag marks were easy to follow out into the woods, where the butchered hulk of the pump would be found, with the cash collection cassette ripped or cut out of the machine. (No one thought that a pickup truck could pull one off the gas station island and off the site. Or a couple of South GA rebels who wondered after watching a hundred folks fill up from that pump cuz gas stations were closed due to the holiday and wonder..."How much money ya think is in that thing??)

    DBMBA theme is "it will look GREAT and get the company needed attention and funding!"

    Derswede

    (Now working for only ONE dumbass.....me.)
     
  6. Jun 22, 2019 #6

    12notes

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    You might want to look at how small the wingtip propellers are before you claim they will hit the runway, there's at least 2 feet of ground clearance, that will allow some bank angle.

    You might also want to look at some of the side views to see how high the tailwheel holds the tail, the fuselage is nearly level, there is not much difference in ground incidence between it and a nose wheel plane. And we have no idea how that gear was designed, what that does to actual liftoff speeds, and why they chose that. It could be softly sprung and have a long travel so it squats on takeoff. It might raise up for passenger ingress/egress.

    I wish people on here were excited about new planes, instead of trying to rip to shreds any attempt at doing anything new, or claiming that any company with any ambition whatsoever doesn't have anyone that knows what they are doing. Especially when it's based on one picture and a single non-technical article.

    They're not a 3D model and impossible dreams, they've built a new design of plane and are planning on flight testing this year. Maybe, MAYBE we should let them test it before claiming what a sham the company's founders and designers are, how big a failure this plane will be at meeting it's goals, and why the designers should be shot for their idiotic feature we know is wrong from that one photo and nearly zero actual information.

    This is becoming a site I don't want to read threads on new plane designs on anything but planes that could have been built 50 years ago, because the comments are mostly negative and frequently unfounded. It's repetitious, predictable, and persistent on here, and getting really old.
     
    Last edited: Jun 23, 2019
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  7. Jun 22, 2019 #7

    TerryM76

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    Well said. Thank you.

    As a side note, I will be in Louisville for Skills USA national event for the entire week......arrive tomorrow evening.

    Terry
     
  8. Jun 23, 2019 #8

    Jman

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    The comment about developing a tailwheel where very few tailwheel pilots exist anymore, is an interesting Point. It brings to mind the first mission helicopter I flew in the Army (OH-58DR). You had to constantly dance on the pedals to keep it behaved. My last assignment was flying MH-47Gs and, with that aircraft, I could leave me feet flat on the floor for the entire flight. In fact, from take off to touch down I really didn't need to touch any of the controls if I was willing to punch some buttons. With advances in fly-by-wire and Digital Automatic Flight Controls Systems, I bet you could make a tailwheel handle like a nose wheel. Maybe even reduce the skill required to prevent a prop strike during a crosswind takeoff or landing. Food for thought.
     
  9. Jun 23, 2019 #9

    Tiger Tim

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    The Eviation plane is a hybrid (I think) and IIRC the wing tip props are electrically driven. I expect they’re out at the tips in some attempt at vortex reduction to help cut drag and increase efficiency.

    As for the landing gear configuration the original renderings of this plane a couple year starts ago showed it on tricycle landing gear. Because most of the airframe and systems are behind the wing, I speculate that they put the battery pack in the nose to balance it. Part of me wonders if the energy density promises they were promised never came through so the pack got bigger until there was no space left to retract the nose gear into. This whole plane comes off to me as a series of unconventional compromises and that could be one more.

    I try not to be a keyboard commando calling people incompetent when I have zero internal details of their project, but I’m certainly interested in watching the development of this thing.
     
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  10. Jun 23, 2019 #10

    BJC

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    See https://www.eviation.co/alice/
    Given:
    Range of 640 miles at 240 knots (plus the added regulatory reserve)
    No comment about battery technology, other than “Li-lon - 900 kWh”
    A configuration that severely limits the ability to achieve typical AoAs for takeoff and landing
    A configuration that severely limits crosswind capability
    A configuration that severely limits use of power with a failed wing tip propeller/motor/controller
    A configuration / wing placement that will present challenges to balance

    Perhaps when they actually fly something and provide some real performance numbers ... Until then, I see nothing wrong with a skeptical attitude about this vaporware.


    BJC
     
  11. Jun 23, 2019 #11

    BJC

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    I’ve never piloted a helicopter, but I have “flown” the Blackhawk simulator at Fort Bragg. It has lots of automation. The yaw control pedals are not even active above a set speed, about 55 knots, IIRC. (It did not like my attempts at a hammerhead.) To transition from cruise to descend for landing, simply push down on the collective; no need to do anything with the cyclic. Strange stuff for this fly-for-fun fixed wing pilot.


    BJC
     
  12. Jun 23, 2019 #12

    BBerson

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    I suppose the tip props could work with fast reacting gyro sensors to limit yaw in the case of a failed prop. To land a taildragger while crabbed is almost impossible with human skill. Again, I suppose the automated controller could "yaw" the plane to align it with the runway heading at the instant of touchdown. This yaw could be done with differential prop rpm.
    But not much a pilot could do to "hand" fly it. It could takeoff in level attitude if wing incidence is variable.
     
  13. Jun 23, 2019 #13

    Dan Thomas

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    Crosswinds are not defeated by yawing the airplane. You either crab it on, which you can get away with in a trike if it's well-designed, but a taildragger will kill you for that. Or you have to bank the airplane to tilt the lift vector against the wind, and in this airplane it would be impossible without damaging propellers.

    I've been around a long time and have seen some designs that were supposed to revolutionize everything, hundreds of them since I learned to fly in the early '70s. And I have plenty of taildragger time, and was a flight instructor in both taildraggers and trikes. And I'm an aircraft maintenance engineer. A design like this just stands out as requiring so many automated crutches to make it work that it scares me. The failure of any of the fancy idiot-proofing means disaster. Ejection seats in an airplane like this aren't acceptable.

    Yes, we will wait for the testing and some more info as to how they make it workable. I just hope we don't wait for 40 years like we did with Moller.
     
  14. Jun 23, 2019 #14

    BBerson

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    Right, that's what I was getting at. A taildragger can't be landed crabbed like an Ercoupe or 737. Any taildragger pilot knows that. They must not be taildragger pilots or they don't care.
     
  15. Jun 23, 2019 #15

    TFF

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    It’s obvious it’s a “big”Bugatti racer. I guess they can put all that batteries in the nose for CG.
     
  16. Jun 23, 2019 #16

    mm4440

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    Tip props can reduce induced drag, increasing cruise efficiency especially at high altitude which is useful for electrics as it is for jets. The worst taildragger problem, directional instability on the ground, can be solved with a fixed tailwheel and castering/steerable mains. "Bass Akwards" is the title of a couple of articles I authored. We have been trying to steer the wrong end. It as as simple as that.
     
  17. Jun 23, 2019 #17

    henryk

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    -similar solution,energyseving...

     
  18. Jun 23, 2019 #18

    Dan Thomas

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    Are there links to those articles you wrote? Would be interesting.

    There was crosswind gear available on the Cessna 170 and perhaps some other airplanes. It castered to discourage groundlooping, but was not widely received. You don't see it on any production taildraggers these days.

    Another issue I'm wondering about with steerable taildragger mains would be the forces required to control them through the rudder pedals. And the corollary to that is the relative lack of weight and traction on the tailwheel due to its long arm from the CG.

    So many ideas have been tried and found wanting. Aviation history--even in my own 66 years--is full of enthusiastic propositions that just never panned out. One of the big mistakes inventors make is to publish their ideas with all the performance projections, and when (if) the machine becomes reality it usually fails to reach that standard. That just brings ridicule and disillusionment. And then there's the already-mentioned investment scams that are particulary successful among the uninitiated. Among us older guys the Moller Aircar is the classic example of that: https://en.wikipedia.org/wiki/Moller_M400_Skycar

    A couple of excerpts:

    The Moller Skycar is a prototype personal VTOL (vertical take-off and landing) aircraft – a "flying car" – invented by Paul Moller who has been attempting to develop such a vehicle type for more than fifty years.[2] As of 2018, no Moller air vehicle has successfully flown in free, non-tethered flight.

    After forty years and $100,000,000 in expenditure[4] the Skycar demonstrated tethered hovering capability in 2003.[5] It has been extensively marketed for pre-order sale since the 1990s as Moller attempted to raise more money for development.

    In April 2009, the National Post characterized the Moller M400 Skycar as a "failure", and described the Moller company as "no longer believable enough to gain investors".[6] On May 18, 2009, Paul Moller filed for personal protection under the Chapter 11 reorganization provisions of the federal bankruptcy law[7] and it is unknown how this will impact the fate of his ideas; Moller International itself did not file for bankruptcy but reduced operations.[8]


    That sort of stuff--and it's not alone at all--tends to make seniors skeptical. Way back in the late '70s a friend was all ready to send his deposit to Moller, and I couldn't dissuade him. Some folks are just too optimistic and trusting. I don't know if he ever sent the money. It's long gone if he did.

    All through my growing-up years, long before the internet, I read the magazines aimed at guys like me. Mechanix Illustrated. Popular Mechanics. Science and Mechanics. Popular Science. All of them, every three months or so, had another breathless article about the newest revolutionary airplane or helicopter or engine. Years of that sort of thing. I can count on one hand the machines that actually made it: The Wankel Rotary engine. Rutan Varieze and its derivatives. Some others, like the Beech Starship, made it but were failures to the point that Beech bought them all back. So, today, we're left with horizontally-opposed four-bangers and a few European diesels that are still struggling to overcome technical issues. Most brand-new light airplanes are of conventional tractor configuration. Helicopters are still using the same controls they did 70 years ago; the real advances are in blade articulation technology--elastomerics, flex straps and all that.

    If there will be any really revolutionary machines I believe they'll be VTOLs. Big quadcopters. And they'll need much larger battery capacity than we have now, and some serious forms of redundancy; they don't autorotate like a helicopter. The drive systems MUST work absolutely reliably.
     
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  19. Jun 23, 2019 #19

    BJC

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    Amen, Dan, amen.
     
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  20. Jun 24, 2019 #20

    12notes

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    Apparently, the definition of vaporware is not understood here. Vaporware is a project that is advertised but never actually gets beyond the concept or design phase.

    They showed up at an airshow with the prototype. This is the exact opposite of vaporware. They have hardware. If it doesn't meet all of it's goals, it's still not vaporware. If it never leaves the ground it's still not vaporware. They built the plane, it's real, and they are planning on flying it.

    I'm not sure of the point of the tailwheel pilot comments. It's not a difficult endorsement, way easier to get than any type rating.

    I would hesitate to call anything a severely limiting factor with such limited information about the plane.

    We don't know the tailwheel design and mechanism. It may not take off/land in the same attitude as when the passengers get on.We know exactly zero about engine-out and crosswind scenarios. The tip motors could easily be designed to stop if the other tip motor does. The single motor in the back may provide enough thrust to climb by itself. They might be designed to stop before landing with the props in the position that gives the largest ground clearance, and restart on go around once sufficient ground clearance is available. There's options with an electric motor that aren't realistic with a piston/turbine.

    I'm not an expert. I've not designed any planes, I haven't even finished building one yet. But if I can think of a few ways to make this plane practical, maybe some of the people involved who have designed and built this plane may have thought of these things and came up with better solutions than I could.

    Other than "told you so" bragging rights, I don't see the point in predicting problems now with no actual information of the plane itself.
    It's probably much better to assume that at least one of these people involved has actual knowledge of flight dynamics than continue on as if the very thought of a crosswind never entered their mind.

    They designed and built a plane, we should be glad for the attempt even if it doesn't meet their performance expectations. Just because you wouldn't have designed it that way doesn't mean there aren't good reasons for it.

    "Trying is the first step towards failure." - Homer Simpson
     

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