Latest on Altaeros, Joby, AWE pioneers

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Altaeros: The predicted abandonment of their flying donut and original stated AWE purpose, and retreat to “providing wifi”, for Altaeros, was interesting to see.

Strangely, today their website attempts to erase their former position as a top “poster-child” of AWE, pretending it never happened.

Here’s a cut-paste from the above link:

Altaeros’ History
Altaeros spun out of MIT in 2010 on a mission to make the world’s first autonomous aerostat. We released our first autonomous aerostat, the SuperTower, in 2019. The SuperTower is an aerial platform designed to bring affordable services anywhere, and everywhere they are needed to help businesses and communities access the basic building blocks to allow for prosperity.

Huh? No mention of the “BAT” (Buoyant Airborne Turbine), the subject of maybe thousands of articles, still cited as a current, promising AWE design to this very day by uninformed authors?
Just google Altaeros and click on “images” - who are they kidding?

Wow, that is whacky, huh? Not even the slightest mention of their AWE roots. I’m hesitant to point out, to me, this seems dishonest. Saying they started in 2010 pursuing an automated aerostat, with no mention of their original AWE roots, is just a mis-statement as far as I can see. How could they just leave out that “little detail”? I mean, the BAT is what they are famous for, whereas the supposed “wifi” (internet?) thing most people have never heard of. (Note: Google (now Alphabet) has abandoned their balloon-lofted wifi-internet “Project Loon” as just a bit too “looney” to ever work out…)

Well, anyway, at least Altaeros are, supposedly, trying something…

The next topic is Joby - JoeBen Bevirt was originally pursuing a flygen AWE system similar to Makani. That was way back in 2009. It seemed significant that JoeBen quickly (a couple years or so?) pivoted away from AWE, while making his electric motor/generators available for purchase by others, mostly as motors for aviation. Today, Joby Aviation has something like 800 employees and seems to be making significant headway in the “flying car” or “flying taxi” space, which essentially builds multi-rotor drones large enough to carry passengers. While attempts to get a new aircraft type-certified is a classic risky endeavor, they do seem like one of the leaders in this seemingly-futuristic field. How it turns out we have yet to see. :slight_smile:

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The idea of carrying a wind turbine protected by the aerostat is perhaps not so bad. The doughnut shape induces a large consumption of fabric surface compared to the volume, which moreover seems very high compared to the wind turbine itself: a small wind turbine for a large balloon.

Moreover, I am not sure that the wind easily reaches the turbine due to the angle of attack required for additional aerodynamic lift.

It would be interesting if Altaeros would publish the technical and economic reasons for abandoning the project.

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Hi Pierre: Yes, that was the showstopper, right there. One more example of “The Professor Crackpot Syndrome”: adding another invention that ruins the main invention. The donut hole just happened to be where most of the buoyancy would have been without the hole. So the hole ruined the idea. I believe this is one more case of allowing the patent system to ruin an invention. “There’s nothing wrong with this idea except the main feature!”

Many companies hesitate to pursue any idea that is "just " public domain. They have to find a new angle to patent, then they have to (hopefully) “monetize” the patent. So they get stuck with a worse idea than if they had no patent.

Meanwhile the idea seemed compelling at first glance. I’d categorize it at the level of a junior-high-school sketch in the margins of a textbook or notebook. Innovative enough to get attention, yet lacking in common sense, since the benefits of the hole were outweighed by the loss of buoyancy and structural integrity. “But that’s what the patent says!”

Throwing the whole idea away to pursue wifi was disappointing. Seems like the only skill they had attained was filling an envelope with helium and letting it go up. They just totally gave up on AWE and went to a boring old regular blimp, sending power UP the tether instead of down. Predictable example of “mission-creep” and “retreat”.

At that point I figured they would never go anywhere. Joby: trying to remember if I have traded their stock. It’s currently down around $5. On the one hand, JoBen BeVirt is a pioneering person who knows how to get things done. On the other hand, in aviation-related efforts, he has a track record of not quite achieving his stated goals and mission-creep. (Stopping AWE efforts, and just producing motors). Sure has hired a lot of people though. Will flying taxis in common use emerge from his efforts? Hard to say, but at least he is trying.

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Technical information on

Now a similar project is running: Familiar looking - Chinese buoyant airborne turbine (BAT)

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Title: A lightweight approach for airborne wind turbine drivetrains
Authors: P. Jaen-Sola, A. S. McDonald, E. Oterkus
Affiliation: University of Strathclyde

  1. Introduction
    Airborne wind turbine systems are gathering increasing attention. These devices are able to harness stronger winds at higher altitudes and with their automated and rapidly deployable system they are suited to niche applications such as emergency power generation. There are a plethora of different airborne wind turbine types, e.g. buoyant [1], flip-wing style (Mars) [2] and kite (SkySails power system) [3]. Buoyant airborne wind turbines are composed of a shell made of high performance fabric filled with helium that lifts a lightweight horizontal axis wind turbine up in the air. High strength tethers keep the turbine in place and send power to the ground station which comprises an autonomous control system and power conditioning equipment [1]. An example of such a system is the Altaeros turbine, shown in Figure 1.
    Although much of the wind turbine technology for these systems is common with their ‘grounded’ cousins, these buoyant systems have some additional design constraints and the design has some extra objectives. One such limitation is the requirement for the wind turbine equipment to be lightweight. This paper concentrates on the drivetrain of the wind turbine and the different potential ways of reducing its mass.
  1. Main body of abstract
    This investigation is based on a 100kW buoyant airborne wind turbine with a swept area of 93.5m2 and 5.5m rotor radius. With a rotor speed of 140 rpm, the low speed shaft nominal torque is 6.8kNm. As explained, the turbine drivetrain must be as light as possible to be lifted up in the air.

See the Figure 4 about the “total drivetrain mass (kg)”: from slightly above 600 kg with gearbox ratio of 1, to slightly above 400 kg with gearbox ratio of 4.

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Hi Pierre: This perhaps 10-year-old paper is nothing but retarded, know-nothing sh*t, by one more “idiot, idiot, idiot”, even mentioninng the “MARS” system, and pretending a 5.5 meter diameter turbine could produce 100 kW. Our 6.5 meter diameter turbine here produces 10 kW, a little more in high winds till the inverter lets it go. And in the full power range, the RPM is up around 300-400.
As far as what Altaeros and Joby are up to, Altaeros is apparently up to nothing after “pivoting” to wifi blimps.
Joby is one of many companies pretending to have a “solution” to get people to the airport faster - they all say the same thing: 4 passengers and a pilot. Billions wasted, for a tiny niche market, if they can ever get anything certified. After giving up on the “great idea” of AWE, Joby has been on the “great idea” of airport commuting for 15 years now with no positive results except self-generated press releases about minor supposed steps forward, based on a lot of government funding.

Once a “genius”, always a “genius”. :slight_smile:

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So the rotor diameter is 11 m.

By a fast calculation, with a Cp of 0.4 and wind speed of 10 m/s, the power would be 22 kW. Let us try with a wind speed of 15 m/s: 75 kW. And 15 m/s is generally above the nominal wind speed. So, to achieve 100 kW, the shroud should be very efficient, but it is likely not possible by the requirement of a positive angle of attack to ensure some lift. There is missing data.

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Hi Pierre: You’re right - I should have read it more carefully before commenting.
Radius is not diameter. Duh on me.
However, the conversation in that document could not take place among “real wind people”.

Here’s my friend Mike Bergey’s newest wind turbine model:

Excel 15 - Bergey Windpower Co.

It is now their only product, rated at 15 kW.

It’s the best buy, and most reliable small turbine available.
Rotor Diameter 31.5 ft (9.6m)
AWEA Rated Power 15.6 kW at 11m/s (24.5 mph)
Nominal Peak Power 25 kW @14 m/s (31 mph)*

So it’s almost the size of the proposed turbine in that paper.
This suggests the turbine in that paper if optimal, and if it even actually existed, might possibly produce maybe 30 kW. I’d hazard to guess 40 kW would be about the highest you could expect under any circumstances if shrouded, but then you get back to the reasons nobody uses shrouds in the first place - near-supersonic blades that make too much noise and often self-destruct.

I will say though, that this relatively new Bergey model DOES have a slightly larger diameter for its rated output than required, because it’s designed to produce in low wind speeds due to that extra rotor area, and it uses electric-braking stall-control for overspeed protection.

Meanwhile, small turbines are rated at 11 m/S (24.5 MPH) NOT 14 m/s (31 MPH)

Here’s a 60-kW-rated turbine.

60kW Small Wind Turbine | Renewable On-Grid & Off-Grid Energy Systems

It has TWICE the swept area of the proposed turbine of that paper, and weighs 6000 kg - not likely to be easily lofted by a blimp or balloon of any reasonable size.

As long as people have no experience in wind energy, they can make whatever bizarre assertions they want, and never get anywhere, whereas for “real wind people”, it’s all “been-there, done-that” stuff.

Even anyone who is just familiar with real wind products knows more than people writing these papers. The problem is “really smart people” who think they have nothing to learn, and can therefore just tell everyone how to do things based on their first impressions, without knowing their ass from a hole in the ground. As the saying goes, “They don’t know what they don’t know.” :slight_smile: