Hmm, not really the standard 1.3 times stall speed. This is way behind the drag curve.

That works out to an AOA of about 0.80, way high. In gusty conditions, you have almost no stall margin, and you are dragging it in very slow.

This is the last plane I want to be in during a microburst, no speed margin.


That's 1.3 stall, AOA 0.6.

Best L/D is about 0.35 to 0.40, so they are operating far from that.


Is the battery not part of the "empty weight"?

If we add empty plus battery, useful load is 1449 lbs.


What is Vr, rotate speed?

The numbers are screwy and weird.

Mike C.

I'd have never thought a rocket landing the way they do,
like balancing a pencil on your fingertip,
was possible.

I still marvel at it.

If they can figure that out,
they'll figure this out.

They "figured out" how to land a rocket vertically with the Apollo Lunar Lander over 50 years ago using a thousand times less onboard computing power than today's smart watches. Of course the lack of atmospheric drag and the lower gravity of the Moon may have made that a bit easier but it's still just based on control theory worked out a long time ago.

"Figuring out" how to compensate for excessive wing loading and insufficient aspect ratio is a much tougher nut to crack. Just ask Peter Muller.

1969 moon landing.

Not exactly new tech to do propulsive landing.

For 20 years I have been seeing sensational articles claiming huge leaps in battery energy density.

Like this one just days old:

"China’s new 600Wh/kg lithium battery could double energy density, boost EV range"

https://interestingengineering.com/ener ... gy-density

These never materialize. There is always some issue or exaggeration or outright lie in there. You can tell these articles are fluff from the total lack of technical detail. There are also warning signs like "It was also able to safely survive 25 full pack cycles without any noticeable instability or degradation.". Conclusion: the article is very premature since testing has hardly started, and the risk exists these batteries have really short cycle life.

Meaningfully surpassing the 300 wh/kg level has been hard and not much progress has been made in 20 years.

Mike C.

1969 moon landing.

Not exactly new tech to do propulsive landing.
Mike C.

Wasn't the moon landing manual?

iirc Neil Armstrong had to visually pick a landing site after overflying a rocky area, then land.

The first one was manual but AFaIK several subsequent landings were automatic.

The company has raised over $1B in funding.

To develop that product? That will never produce a decent ROI. Too specialized, and as others have pointed out, maybe it makes a good trainer. But how could it ever meet the certification for Normal or Utility category? So, what they have now is a very unique, experimental category trainer?

What’s the long term business plan? Replace 182s, Mooneys, Bonanzas, and Cirrus?

I think the only thing they’re going to produce are some clever experimental demonstration aircraft and a lot of unhappy investors.

They "figured out" how to land a rocket vertically with the Apollo Lunar Lander over 50 years ago using a thousand times less onboard computing power than today's smart watches. Of course the lack of atmospheric drag and the lower gravity of the Moon may have made that a bit easier but it's still just based on control theory worked out a long time ago.

"Figuring out" how to compensate for excessive wing loading and insufficient aspect ratio is a much tougher nut to crack. Just ask Peter Muller.

Step 1: admitting denial

Here is a piece about a technology that may reduce battery weight required for transportation uses.
https://medium.com/@daiglegregory/an-ev ... e49f06d566

The physics is not easy to explain in simple way.

Bob Belovich

The article does not explain the E-Cat physics at all. Nor do the linked articles.

An aphorism and a law are best used to describe that:

The Law of Conservation of Energy always applies (that’s why it’s a law)

The E-Cat fits the bill of “too good to be true”

This farce has been around for more than 15 years without any meaningful positive results.

http://theoildrum.com/node/8140

This farce has been around for more than 15 years without any meaningful positive results.

http://theoildrum.com/node/8140