On Electric Aircraft

On Tuesday, February 11, 2020 at 4:33:26 AM UTC-8, Martin Gregorie wrote:

..The one thing we both missed, though is that a good brushless motor plus
its controller will be a lighter and smaller than the equivalent ICE
piston engine driving a propeller...

Not only that, but it delivers smoother power with less vibration, delivers it the moment it is started, requires less service infrastructure (starting, lubrication, cooling, exhaust, etc), and can easily be positioned for stowage. It runs cleaner and cooler and more predictably under a wider range of conditions, and is more easily monitored for performance and troubleshooting.

--Bob K.

On Tue, 11 Feb 2020 10:16:45 -0800, Bob Kuykendall wrote:

On Tuesday, February 11, 2020 at 4:33:26 AM UTC-8, Martin Gregorie
wrote:

..The one thing we both missed, though is that a good brushless motor
plus its controller will be a lighter and smaller than the equivalent
ICE piston engine driving a propeller...

Not only that, but it delivers smoother power with less vibration,
delivers it the moment it is started, requires less service
infrastructure (starting, lubrication, cooling, exhaust, etc), and can
easily be positioned for stowage. It runs cleaner and cooler and more
predictably under a wider range of conditions, and is more easily
monitored for performance and troubleshooting.

Another thing, but this probably doesn't affect us much: a brushless
motor, which all these units are, has its rpm set primarily by the rate
at which the controller switches power round its (static) field coils
and, when driving a propeller, isn't much affected by the load its
working against. Its one reason electric brushless motors are popular
with the RC and CL aerobatic crowd - the nearly constant RPM causes
airspeed on uplines and downlines to be more constant than it ever was
with IC engines.


--
Martin | martin at
Gregorie | gregorie dot org

What a wonderful way to spend a snowy morning, discussing the weight of
a full versus an empty battery!

What if we talked in terms of mass instead of weight? :-D

Seriously, I got a lot of entertainment after the thread went off topic
as is so normal with RASicrucians.Â* I especially liked the comparison
that Bob made of a wound versus unwound watch or toy. I've been banging
my head against the wall trying to see that in the context of the Laws
of Conservation of Matter and Energy.

More coffee is in order...

On 2/11/2020 11:34 AM, Martin Gregorie wrote:
On Tue, 11 Feb 2020 10:16:45 -0800, Bob Kuykendall wrote:

On Tuesday, February 11, 2020 at 4:33:26 AM UTC-8, Martin Gregorie
wrote:

..The one thing we both missed, though is that a good brushless motor
plus its controller will be a lighter and smaller than the equivalent
ICE piston engine driving a propeller...
Not only that, but it delivers smoother power with less vibration,
delivers it the moment it is started, requires less service
infrastructure (starting, lubrication, cooling, exhaust, etc), and can
easily be positioned for stowage. It runs cleaner and cooler and more
predictably under a wider range of conditions, and is more easily
monitored for performance and troubleshooting.

Another thing, but this probably doesn't affect us much: a brushless
motor, which all these units are, has its rpm set primarily by the rate
at which the controller switches power round its (static) field coils
and, when driving a propeller, isn't much affected by the load its
working against. Its one reason electric brushless motors are popular
with the RC and CL aerobatic crowd - the nearly constant RPM causes
airspeed on uplines and downlines to be more constant than it ever was
with IC engines.



--
Dan, 5J

You mean that a glider hs a higher mass after releasing from tow because you added potential energy??