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MIT Tailsitter Drone Acrobatics

aera.mit.edu

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Re: MIT Tailsitter Drone Acrobatics

#11

Post by w-ll »

fwlr wrote: post #7
njoubert wrote: post #6

Ah, tailsitters. Everyone loves the theory, then the practical realities of the takeoff position exposing the entire wing surface to the prevailing wind quickly kills real-world applications. I remember back during the 3D Robotics heyday watching Chris Anderson repeatedly run down to set his tailsitter upright, take a few steps back, only to watch it fall over again.

For vertical takeoff and landing the wing surface is mostly irrelevant, right? Seems like if you gave the rotors a “landing configuration” where they rotated 90 degrees you could lay the wing flat on the ground.

The wings look like they have smaller control surfaces the full wings are not. But to make cheap drones that are dropped or launches from a cheap taco holder its probably fine.

Re: MIT Tailsitter Drone Acrobatics

#12

Post by NortySpock »

xwdv wrote: post #4

Do these designs scale up? Don’t see why we haven’t created full sized aircraft with this form factor. Seems like it would make a great aerial weapons platform.

It's all fun and games until the engine or propeller goes out....

Mustard on YouTube did a video on the French SNECMA Coléoptère, which had a ring for a wing. It tended to rotate while hovering, and hard to steer during landing.

(9 min) https://youtu.be/unz6mfjS4ws

Re: MIT Tailsitter Drone Acrobatics

#13

Post by ta8903 »

njoubert wrote: post #6

Ah, tailsitters. Everyone loves the theory, then the practical realities of the takeoff position exposing the entire wing surface to the prevailing wind quickly kills real-world applications. I remember back during the 3D Robotics heyday watching Chris Anderson repeatedly run down to set his tailsitter upright, take a few steps back, only to watch it fall over again.

Can't you take off from a closed box? For landing the flight controller should be able to compensate for the wind and come down in a somewhat vertical position.

Re: MIT Tailsitter Drone Acrobatics

#14

Post by jasonwatkinspdx »

fwlr wrote: post #7
njoubert wrote: post #6

Ah, tailsitters. Everyone loves the theory, then the practical realities of the takeoff position exposing the entire wing surface to the prevailing wind quickly kills real-world applications. I remember back during the 3D Robotics heyday watching Chris Anderson repeatedly run down to set his tailsitter upright, take a few steps back, only to watch it fall over again.

For vertical takeoff and landing the wing surface is mostly irrelevant, right? Seems like if you gave the rotors a “landing configuration” where they rotated 90 degrees you could lay the wing flat on the ground.

This is the distinction between tilt wing aircraft and tilt rotors. The former were explored in the 60s and found impractical. The latter took longer to develop but are now practical.

The original comment is spot on: hovering vertically with a big wing also vertical just doesn't work well in the real world. That said, the situation might be different for very small drones, for similar reasons to why you don't build full size quadcopters.

Re: MIT Tailsitter Drone Acrobatics

#15

Post by [deleted] »

njoubert wrote: post #6

Ah, tailsitters. Everyone loves the theory, then the practical realities of the takeoff position exposing the entire wing surface to the prevailing wind quickly kills real-world applications. I remember back during the 3D Robotics heyday watching Chris Anderson repeatedly run down to set his tailsitter upright, take a few steps back, only to watch it fall over again.

[deleted]

Re: MIT Tailsitter Drone Acrobatics

#16

Post by neltnerb »

chabons wrote: post #2

Interesting research. Assuming that the benefit of fixed-wing aircraft is efficiency in relatively straight flight, I'm wondering how this aircraft compares in efficiency vs agility against a quadcopter of similar weight.

What would be your guess? I'm reading this as describing straight line wing flight for long distances rapidly shifting to erratic motions if someone doesn't like it existing. I imagine it's much more efficient at that, assuming that shell is mostly batteries anyway.

Very neat to watch, I'd be curious to hear under what conditions it's worse than a quadcopter, perhaps stability or how quick it can turn.

Re: MIT Tailsitter Drone Acrobatics

#17

Post by rikeanimer »

Did no one notice the balls? Those are there so a set of external cameras [think motion capture] can feed in an absolute, essentially perfect state estimate to the control algorithm. It's probably a run of the mill system from Vicon [company].

Essentially if you're running vicon you can make flying things do things like you could make them do programming them in Blender or similar, subject to the [pretty minimal to the human eye] time constants of the mechanical systems. Brushless speed controllers are pretty fast, servos are as well [but way slower]. The end-to-end control loops we are talking about are in the ballpark of 1khz easy and have been for quite some years.

If they had balls they'd take off the balls ;) Other than that it is essentially CGI in real life ;)

Sorry don't mean to be negative it looks cool guys. Now go make it actually cool.

I ain't got no darn PhD in control theory from some fancy skool er nuthin but my gut tells me for this situation it's the state estimation that actually composes the beavers tail under the wattuh of dis dat der prollem.

Re: MIT Tailsitter Drone Acrobatics

#18

Post by rikeanimer »

Ancapistani wrote: post #9
xwdv wrote: post #4

Do these designs scale up? Don’t see why we haven’t created full sized aircraft with this form factor. Seems like it would make a great aerial weapons platform.

It’s definitely been done before. The closest to this design off the top of my head would be the Lockhead XFV (1954): https://en.wikipedia.org/wiki/Lockheed_XFV The idea of a VTOL tailsitter, but without the single primary planar wing surface, goes much further back. The Nazis were in the process of building the Triebflügel at the end of WW2: https://en.wikipedia.org/wiki/Focke-Wulf_Triebflügel

yeah there were a handful of tailsitter designs that era. Cool concepts but pretty much all had an achille's heel or two.

Re: MIT Tailsitter Drone Acrobatics

#20

Post by exDM69 »

rikeanimer wrote: post #17

Did no one notice the balls? Those are there so a set of external cameras [think motion capture] can feed in an absolute, essentially perfect state estimate to the control algorithm. It's probably a run of the mill system from Vicon [company]. Essentially if you're running vicon you can make flying things do things like you could make them do programming them in Blender or similar, subject to the [pretty minimal to t…

I certainly noticed the marker balls, but...

On a quick glance, they do not mention if they are using the external cameras for the control algorithm or just verifying the results. The QR code-like markers on the gates suggests that there is also some onboard cameras.

The statistics on the measurement errors suggests that they have a ground truth (from external cameras?) which they compare to some other source of measurement.

So I would not draw the conclusion that the tracker balls and external cameras are doing all the heavy lifting here.

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