Hybrid Engines??

Have you seen the Sonex e-Flight program?
Or how about the Electric Apis project?http://www.glider-one.si/index.php?o...tpage&Itemid=1

Exciting times!

--Noel

Seen'em, thanks; (I've even had the pleasure of attending one of Pete
Buck's [the brains behind the Sonex project dubbed 'Flash Flight']
presentations on it, and checked out some of their special custom
lithium cells too, then picked his brain for a while..., in addition
to Cafe' green racer updates and Goshawk info...) all very neat, but I
want to know more about these hybrid engines in the 140-200 hp range
that would revolutionize glider towing as we know it... Anyone have
anything to add to this topic? Googling has provided scant little
additional info to me so far...

Exiting times indeed! (except that by the time it's all come to
fruition the air will probably only be designated for UAV's and heavy
iron...)

-Paul

On Mar 13, 10:03*am, sisu1a wrote:

I want to know more about these hybrid engines in the 140-200 hp range
that would revolutionize glider towing as we know it... * *Anyone have

Paul -

I think it would only revolutionize towing if you could either quickly
recharge the cells, or if they had INCREDIBLE capacity! Towing is a
repetitive action that requires a high power output for several
minutes at a time (which translates to a fast discharge, hard on
batteries)... I hate to say it, but I think the physics of an
aerotowing operation mean that it'll be one of the last things that
battery power would be applicable to.

Now winches (especially one that has a serial hybrid drive like the
Chevy Volt) might be another story... Batteries are used extensively
to power R/C glider winches already, and while the draw/load is still
very high, its a much shorter duration than an aerotow.

Nevertheless, I'm psyched about any and all _real-world_ advances in
electric propulsion. Disconnecting "work" or power output from the
source (using electricity as an efficient middle-man) frees up the
national/global infrastructure to adapt more readily to whatever power-
generation system works out to be the best!

Take care,

--Noel

On Fri, 13 Mar 2009 18:08:07 -0700, noel.wade wrote:

Now winches (especially one that has a serial hybrid drive like the
Chevy Volt) might be another story... Batteries are used extensively to
power R/C glider winches already, and while the draw/load is still very
high, its a much shorter duration than an aerotow.

You can have a hybrid winch any time you want.

Just get hold of an Electrostartwinde ESW-2B and park a 15 - 20 kW diesel
trailer generator behind it.



--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

I thought the point was to provide additional horsepower on the ground run
and initial climb out. A Rotax 100hp engine would be able to tow OK
without the extra oompf during the rest of the climb whilst recharging the
battery.

Interesting article here http://news.bbc.co.uk/1/hi/sci/tech/7938001.stm

on Li-ion battery technology and fast charging

Jim


At 01:08 14 March 2009, noel.wade wrote:
On Mar 13, 10:03=A0am, sisu1a wrote:

I want to know more about these hybrid engines in the 140-200 hp range
that would revolutionize glider towing as we know it... =A0 =A0Anyone
hav=
e

Paul -

I think it would only revolutionize towing if you could either quickly
recharge the cells, or if they had INCREDIBLE capacity! Towing is a
repetitive action that requires a high power output for several
minutes at a time (which translates to a fast discharge, hard on
batteries)... I hate to say it, but I think the physics of an
aerotowing operation mean that it'll be one of the last things that
battery power would be applicable to.

Now winches (especially one that has a serial hybrid drive like the
Chevy Volt) might be another story... Batteries are used extensively
to power R/C glider winches already, and while the draw/load is still
very high, its a much shorter duration than an aerotow.

Nevertheless, I'm psyched about any and all _real-world_ advances in
electric propulsion. Disconnecting "work" or power output from the
source (using electricity as an efficient middle-man) frees up the
national/global infrastructure to adapt more readily to whatever power-
generation system works out to be the best!

Take care,

--Noel

How about using the propeller as a generator on the way down?
Recharge the battery. (of course you cant do that with a static prop)

THAT would be a real hybrid :-)

CU
Markus

On Mar 14, 3:54*am, Markus Gayda wrote:
How about using the propeller as a generator on the way down?
Recharge the battery. (of course you cant do that with a static prop)

THAT would be a real hybrid :-)

CU
Markus

Possibly a better approach is to look carefully at propeller
efficiency in the initial acceleration. In the ground roll where the
prop efficiency unlikely to be more than 25%. Touring motorgliders
like airplanes with fixed props are optimized for cruise, not
acceleration.

Small, high RPM props are very bad at very low airspeeds. Big, low
RPM props far better as are ducted fans. Note that helicopters use
huge rotors at around 300 RPM to slowly lift the entire aircraft
straight up. Other VTOL aircraft like the F35B use ducted fans which
are at their best below 75 knots.

The tiny prop is the weak link in current motorglider tugs. It
doesn't look as if it would be hard for the designers to lengthen the
landing gear by 25cm and ask Rotax to supply greater gear reduction
for a bigger, slower prop. A bigger prop would address the slow
acceleration.

The acceleration is still limited by the available power vs the total mass
of the glider and tow plane.

Mike Schumann

"bildan" wrote in message
...
On Mar 14, 3:54 am, Markus Gayda wrote:
How about using the propeller as a generator on the way down?
Recharge the battery. (of course you cant do that with a static prop)

THAT would be a real hybrid :-)

CU
Markus

Possibly a better approach is to look carefully at propeller
efficiency in the initial acceleration. In the ground roll where the
prop efficiency unlikely to be more than 25%. Touring motorgliders
like airplanes with fixed props are optimized for cruise, not
acceleration.

Small, high RPM props are very bad at very low airspeeds. Big, low
RPM props far better as are ducted fans. Note that helicopters use
huge rotors at around 300 RPM to slowly lift the entire aircraft
straight up. Other VTOL aircraft like the F35B use ducted fans which
are at their best below 75 knots.

The tiny prop is the weak link in current motorglider tugs. It
doesn't look as if it would be hard for the designers to lengthen the
landing gear by 25cm and ask Rotax to supply greater gear reduction
for a bigger, slower prop. A bigger prop would address the slow
acceleration.

The acceleration is still limited by the available power vs the total mass
of the glider and tow plane.


Possibly a better approach is to look carefully at propeller
efficiency in the initial acceleration. *In the ground roll where the
prop efficiency unlikely to be more than 25%.

Hmm, perhaps a better idea for a hybrid towplane than these hybrid
engines would be a tug with electric motors in it's wheels to quickly
get the party started... say up to 30mph or so before the prop is
providing primary thrust.

-Paul

PS. Noel, I definitely agree that battery/energy storage technology
needs to improve vastly (including $$$) for these to be truly viable
(read revolutionary) alternatives...

bildan wrote:

Possibly a better approach is to look carefully at propeller
efficiency in the initial acceleration. In the ground roll where the
prop efficiency unlikely to be more than 25%. Touring motorgliders
like airplanes with fixed props are optimized for cruise, not
acceleration.

Small, high RPM props are very bad at very low airspeeds. Big, low
RPM props far better as are ducted fans. Note that helicopters use
huge rotors at around 300 RPM to slowly lift the entire aircraft
straight up. Other VTOL aircraft like the F35B use ducted fans which
are at their best below 75 knots.

The tiny prop is the weak link in current motorglider tugs. It
doesn't look as if it would be hard for the designers to lengthen the
landing gear by 25cm and ask Rotax to supply greater gear reduction
for a bigger, slower prop. A bigger prop would address the slow
acceleration.

The touring motorgliders I'm aware of have either an adjustable
propeller, or three position propeller (feathered, climb, cruise). I
would expect the ones used for towing to have the same; if so, the slow
acceleration may not be a propeller problem, but a power to weight
issue. Once airborne, their better aerodynamic efficiency makes up for
the lower power to weight, but that doesn't help the ground run.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes" http://tinyurl.com/y739x4
* Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Mar 14, 2:45*pm, Eric Greenwell wrote:
bildan wrote:
Possibly a better approach is to look carefully at propeller
efficiency in the initial acceleration. *In the ground roll where the
prop efficiency unlikely to be more than 25%. Touring motorgliders
like airplanes with fixed props are optimized for cruise, not
acceleration.

Small, high RPM props are very bad at very low airspeeds. *Big, low
RPM props far better as are ducted fans. *Note that helicopters use
huge rotors at around 300 RPM to slowly lift the entire aircraft
straight up. *Other VTOL aircraft like the F35B use ducted fans which
are at their best below 75 knots.

The tiny prop is the weak link in current motorglider tugs. *It
doesn't look as if it would be hard for the designers to lengthen the
landing gear by 25cm and ask Rotax to supply greater gear reduction
for a bigger, slower prop. *A bigger prop would address the slow
acceleration.

The touring motorgliders I'm aware of have either an adjustable
propeller, or three position propeller (feathered, climb, cruise). I
would expect the ones used for towing to have the same; if so, the slow
acceleration may not be a propeller problem, but a power to weight
issue. Once airborne, their better aerodynamic efficiency makes up for
the lower power to weight, but that doesn't help the ground run.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* "Transponders in Sailplanes"http://tinyurl.com/y739x4
* * * Sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" atwww.motorglider.org

Eric, it's a disk loading issue. Efficient props accelerate a whole
lot of air a little bit. Small props, regardless of pitch setting,
accelerate a little bit of air a whole lot. The solution to the low
speed efficiency issue is large diameter propellers turning slowly -
like 1000 RPM.

If you can make them work, ducted fans are in their sweet spot at
towing speeds. There's some blimps powered by ducted fans that claim
8 pounds of static thrust per HP - blimps fly at about towing speeds.
That's 800 pounds of thrust for 100HP which should get things rolling
quickly.

I think there are technologies on the horizon that might allow for
electric tugs as long as you were willing to charge them frequently.
The announcement this week in MIT's Technology Review of charging
times in seconds might be one of the breakthroughs.