Earthstar Forums

As those of you flying with a Zero Motorcycles power train know, eGulls can
take advantage of Zero's built-in re-gen capabilities. We don't have brakes
to signal to the controller to re-gen harder, all we can do is coast. In
Sport mode, the prop spins essentially freely when throttle is at idle, but
in ECO mode, the prop slows the plane down noticeably while recharging.
What would the effect be of setting up a Custom mode (via Bluetooth app)
with more aggressive re-gen? In the extreme, would the prop simply stop
spinning at normal approach speeds, and is that when it produces the most
drag? Can it be "broken lose" with a little throttle?
What got me interested in this is my preference of driving my Chevy Bolt EV
exclusively in "L" mode (high re-gen, "single pedal"). I hardly ever touch
the brakes - much like flying my eGull. On the Bolt, I can increase re-gen
via a steering wheel paddle. On the eGull, I would always want strong
re-gen once I pull power back to (past?) idle. This way, the prop acts as a
modulating speed brake (can be dialed in via throttle).
The only time I can imagine where one would want the prop to spin freely is
after you exhausted your charge and have to maximize your glide distance.
But if that happens close to the airport, I would still want to trade
excess altitude for a little re-gen - it won't be enough for a go-around,
but might allow you to stretch your approach at the last second.

I intend to test all this next season (April?).

As an aside, Richard Steeves and I are wondering how many eGulls are flying
now, and how many are under construction or being converted. Mark, can you
enlighten us? Are all eGull owners and pilots on this forum?

As I think I learned, drag is lowest with the prop stopped. A spinning prop would then be an energy waster. Energy recovery would have to be reduced by inefficiencies in the systems. Would have to calculate but may be best to just electrically stop the prop whilst coasting.

If you wanted to descend without speeding up however, regen would be like car brakes and would recover some of the energy that you are asking to be removed (speed).

I’m certain you can control the prop to start windmilling with software (firmware) changes. Don’t know if the zero controller makes that easy or not.

My $.02

Mark Drzymkowski

Right on Mark!
The zero can be set to stop propellor when Regen is set to max. Also more present or gliding.

Happy Flying,
Mark

Sent from our iPhone

Minimum drag when stopped? But maximum drag at highest regen? Lets say, you
have set your Custom mode to maximizes re-gen, and you are in a low-power
descent. Pulling the throttle back would increase re-gen and steepen the
glide angle for a given speed. What happens when re-gen reaches the point
at which the prop stops? Does the plane accelerate, but then slow down as
the prop starts spinning again?
I think I will set my Custom mode to max regen and no limits to power.
During take-off, I have control over how hard I accelerate (might come in
handy on short runways), during cruise I fly at around 10 kW, regardless of
Mode, and during approach I have a controllable speed brake. I don't think
I would use less energy in ECO mode. Airplanes differ from motorcycles by
mostly keeping power levels constant (except aerobatics) - capping
acceleration may offer energy savings on a motorcycle, but not so much for
us. Or?
In the future, on dedicated electric planes, I would expect to be able to
reverse the prop rotation on roll-out. Won't be as powerful as
reverse-thrust jets, but should take a load off the brakes. No need for a
constant speed prop!

Minimum drag when stopped?
YES

But maximum drag at highest regen?
YES, UNTIL IT STOPS. THEN DRAG REDUCTION. LIKE A HELICOPTER ON AUTOROTATE LANDING. THE PROP IS COUNTED AS A DISK.

Lets say, you have set your Custom mode to maximizes re-gen, and you are in a low-power descent. Pulling the throttle back would increase re-gen and steepen the glide angle for a given speed.
SPEED BRAKES!!
MORE DIRECT SPEED CONTROL VS ENGINE

What happens when re-gen reaches the point at which the prop stops?
NEED SPIN TO REGEN

Does the plane accelerate, but then slow down as the prop starts spinning again?
THINK SO


I think I will set my Custom mode to max regen and no limits to power. During take-off, I have control over how hard I accelerate (might come in handy on short runways), during cruise I fly at around 10 kW, regardless of Mode, and during approach I have a controllable speed brake. I don't think I would use less energy in ECO mode. Airplanes differ from motorcycles by mostly keeping power levels constant (except aerobatics) - capping acceleration may offer energy savings on a motorcycle, but not so much for us. Or?
In the future, on dedicated electric planes, I would expect to be able to reverse the prop rotation on roll-out. Won't be as powerful as reverse-thrust jets, but should take a load off the brakes. No need for a constant speed prop!
WILL DOMINATE STOL COMPETITIONS. BEIERLE WAS PRETTY MUCH DOING THAT ALREADY AT OSH

Mark Drzymkowski

It sounds to me like you guys have a good handle on this subject!

Happy Flying,
Mark

Sent from our iPhone