Kitekraft Startup

Seems similar to Makani with a biplane wing. Curious to see how they progress, and I wish them best of luck!

1 Like

Not sure if they use flygen. Propellers / turbines might be exaggerated in the rendering.

We cant be sure no, but more than a few propellers doesnt make sense for VTOL, so I guess flygen is a good bet

1 Like

Wondering why they have the tailplane. Why donā€™t they just use a different amount of drag-loading for steering and stability like multicopters or thrustvectoring if thatā€™s impossible?

A tail provides a lot of torque with minimal drag. And you dont need to know the direction of the airflow in order to get very good performance. Also, counteracting pitch moment of the wing is cheap compared to losses in the propellers.

This is just in general why most planes have tails, its a nice solution

Intuitively the skypull solution makes more sense. [edit: I thought skypull system didnā€™t have control surfaces]
Wondering if there has been done some research on the topic of turbine losses for steering. Probably much of the research on mullticopters can be transferred.

The skypull design is skewed, effectively implementing a tail?

As one wing is forward and one aft, a difference in AoA could be used for pitch control. Not very different compared to a tail

Would have to be like a canard aircraft.That would make the front wing a frontplane or canard and/or the back one a tailplane. But usuall a tailplane would have downward lift. The stability canā€™t be very great with that little leverage. Skypull indeed has controll surfaces over every wing. I really thought they controlled everything via thrust.

The (Kitekraft) biplane kite was also discussed on High lift coefficient and biplane kite. The scientific paper is on
https://www.researchgate.net/publication/320742362_Drag_power_kite_with_very_high_lift_coefficient.

2 Likes

Yepp, itā€™s drag-loaded. The title of the paper says so.

1 Like
1 Like

Just noticed that kitekraft have predicted a levelized cost of energy of 0.25 EUR/kWh.

1 Like

The theory is well explained on:

Website:
http://www.kitekraft.de/

2 Likes

Some internal links related to the discussion: Makani's presentation in AWEC2017, High lift coefficient and biplane kite.

2 Likes

A great set of rebuttals from Florian which distinguish their tech advantages.
Further arguments can be added against the technical conclusions when you consider yet further architectures which were bypassed on the Makani tech roadmap.

Such as when talking about reducing the cost as compared to aircraft when scalingā€¦ The conclusions state

Small systems will struggle to have maintenance costs per unit power as low as
larger systems, regardless of their perceived simplicity, due to the additional
number of components.

Simplicity here seems to point toward software and control simplicity rather than pure architectural simplicity. The advantages of dumb ass network kite turbines seem clear to me for their for pure work function.

Networked kite thinking seems to have been a conceptual leap beyond the reported assessmentā€¦

Multiple kites on a single ground station or a single shared tether have some clear
beneļ¬ts, but those beneļ¬ts are only accessible after solving many novel control
challenges, presenting a diļ¬ƒcult development story.
a. Multi-kites begin to see induced losses similar to traditional wind turbines,
somewhat degrading their beneļ¬ts.
b. Simpler conļ¬gurations of multi-kites may be worthwhile to pursue once a reliable
single kite product is well developed and tested.

the reliability of networks comes from group path stability

2 Likes

1 Like