Did Midnight achieve 'Full Transition' to Wing-Borne Flight' ?
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- Опубликовано: 26 июн 2024
- We took a look at what Archer announced on June 12th about Midnight having 'transitioned' on June 8. It isn't clear whether Archer has achieved 'Full Transition to Wing-Borne Flight' as defined in its Jan 3 2023 agreement with Stellantis. Archer couldn't make such determination four days after the flight.
Addendum: the slide show at time stamp 7:19 references April 2023. This should be April 2024 as was made clear on the prior slide.
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Full disclosure: At the time of writing we are short Archer, a position we took after we noticed something in the field where we are observing test flights. Archer had made an important change to its design which the company had not talked about. We published a video about this subject on May 30. We have been long Archer in the past, and exited out of that position with a profit.
Just on transition per se, if everything goes right the aircraft will remain in trim throughout the 'handover' of the "anti gravity" function from proprotors (powered) to the wing AND tail , it is important to appreciate that the tail's primary function is to trim the whole airplane ie keep it balanced and slso to allow for control in pitch and yaw. There does not appear to be any movement of the tail surfaces at all as must be required during and after a transition , it may be that they have to have lift from the aft props for equilibrium ( ie not transitioned ) and showing the aircraft to be tail heavy. With Joby both the tail and wing are blown by slipstream and there is huge ruddervator deflection as well , the two blade props shown are fixed pitch that would be slower to respond and build up thrust differently to those forward (more 'fixes' in the control software at a minimum if not actually sufficient trim available, the original Uber animations had fixed rear props also as does the VX4 , no way could the Uber elevate depictions trim in pitch with multiple props on the rear tail boom so that was artistic licence only. There is a legitimate question as to viability here and cruise flight would demand tail control surfaces ( not just fixed as might be the case)
Videos made by this channel are so great and inspiring! Hope to connect with you and discuss evtol worldwide.
It's possible Archer kept the outside rotors spinning because at speeds of 100kts, Midnights' wing may not provide sufficient lift. I always thought Midnights wing is a rather odd wing design, especially as you go outboard. With the downward wingtip, it could be efficient for climb during vtol but could reduce the lift needed for forward flight at lower speeds. Time will tell as Archer continues to test and increases their forward cruising speed to see if the rear blades count is reduced to 2 blades per motor.
Thanks for your perceptive independent research, I was not aware of the clause in the 'agreement' with Stellantis specifying full transition until now (also notable is the "exhibit" naming , is this indicative of some (more) legal issues ? Bearing in mind the sordid lawsuit with Kittyhawk/Paige/Google over theft of IP and copying of the basic design from Wisk (Munz et al having downloaded thousands of pages of in house data etc as well, the whole "origin story" is worrying as was the departure of the co founder etc etc etc - all being warning signs about their business ethics. As you had already noted (and i did 12 months ago on YT) the aircraft shown in the videos does not conform to the design concept or 'visuals' irrespective of whether IT transitioned. The aft props induced downwash behind the wing and so add to lift (the Dornier Do 29 used this concept 60 years ago) whereas the front props REDUCE lift during conversion by inducing negative angle of attack and create high pitching moments from propeller normal force (the Curtiss Wright X19 vtol employed this force as 'radial lift force' , it could be that the ridiculous offset of the front propellers and the normal force Require the rear props to cancel it out ( even when fully tilted to horizontal the wing upwash field creates a normal force moment . I had to go into this subject in some depth with my Opal tail pusher in the late 70s as control inputs deflect the inflow field and the propeller is far from the CG. With billions of dollars floating around and "sales' of hundreds of non existent aircraft being touted a little more truth in advertising and engineering would be nice. Good work.
The EVTOL Research Channel...... yet EVERY VIDEO IS ABOUT ARCHER AVIATION! ......hmmm.... Either this channel is being funded by a short seller, or perhaps a fired ex-employee!!!😂
I don't think you can say that the inside props were turning slower. A different speed for sure. The video may look like that but it could be an artifact of the camera frame rate and the inner props are blurry. Wings generate more lift inboard than outboard, which means more downwash behind the wing inboard, which would mean those props turning faster. I'm not sure it makes any difference to the success of the flight.
At 90 knots IAS the wings should be producing enough lift already...the slowdown transition is the more tricky phase...