Here's one of the first in the free piston engine generators to come, 42% efficiency, as light as it gets. Amazing Swiss, Daniel Hagen, he self funded it for over six years around the turn of century
http://www.beetron.ch
rc
Beetron in an eGull
-
blaswichk
Re: Beetron in an eGull
Wow, maybe that could be the small in-cruise power, and battery storage for take-off and climb to altitudes. Electric light-flight is coming to my neighborhood soon!
-
bruce.markle
Re: Beetron in an eGull
The 7 page viewgraph pitch shows two free pistons with a common combustion
chamber in the center, pistons are bounced back to center using a
pressurized dome on each end. The translating pistons have permanent
magnets that induce power into stationary coils on what would be the
cylinders. Looks like the bottom of the pistons suck in charge from the
carb on the "out" stroke and then pressurize a separate center plenum on the
"in" stroke. At the far end of the "out" stroke the pistons go past ports,
intake on one end and exhaust on the other, and the pressurized plenum
injects the charge and scavenges the exhaust. 8 check valves or reeds and
shown for all this.
The You tube video has what MAY be a different configuration [2 combustion
chambers, one on each end, with the generator in the middle?]. An intake
manifold runs from a carb to a tee which feeds ports on both "cylinders"
about halfway out; exhaust stacks come out from the very end of each "head".
There is a "plug" like thing on the center of the end of each "head"; can't
tell what this is or does. There are wires running to what are likely to be
glow plugs just slightly outboard from the intake port, two per end (it
looks like standard model airplane glow plug energizers used when starting
and then removed). There are some wires coming from the center of the
contraption (the "generator") that may be generating power eventually from
it, but do not appear to be in the video. It clearly is happy running on
its own. Don't see what is making the pistons bounce back toward each other
if there really are combustion chambers on each end.
Any other thoughts about how the engine in the video is working?
The 30 KW version is sized at 19.3" x 7.1" x 9.25". No weights given, but
basically the size of a breadbox won't be too bad. Sign me up for one,
would make a great sustainer [cruise power plus plenty left over to charge
the batteries you used to help takeoff and climb]. 30 KW actually more than
you really would need for a E-Gull by about a factor of two.
Bruce
chamber in the center, pistons are bounced back to center using a
pressurized dome on each end. The translating pistons have permanent
magnets that induce power into stationary coils on what would be the
cylinders. Looks like the bottom of the pistons suck in charge from the
carb on the "out" stroke and then pressurize a separate center plenum on the
"in" stroke. At the far end of the "out" stroke the pistons go past ports,
intake on one end and exhaust on the other, and the pressurized plenum
injects the charge and scavenges the exhaust. 8 check valves or reeds and
shown for all this.
The You tube video has what MAY be a different configuration [2 combustion
chambers, one on each end, with the generator in the middle?]. An intake
manifold runs from a carb to a tee which feeds ports on both "cylinders"
about halfway out; exhaust stacks come out from the very end of each "head".
There is a "plug" like thing on the center of the end of each "head"; can't
tell what this is or does. There are wires running to what are likely to be
glow plugs just slightly outboard from the intake port, two per end (it
looks like standard model airplane glow plug energizers used when starting
and then removed). There are some wires coming from the center of the
contraption (the "generator") that may be generating power eventually from
it, but do not appear to be in the video. It clearly is happy running on
its own. Don't see what is making the pistons bounce back toward each other
if there really are combustion chambers on each end.
Any other thoughts about how the engine in the video is working?
The 30 KW version is sized at 19.3" x 7.1" x 9.25". No weights given, but
basically the size of a breadbox won't be too bad. Sign me up for one,
would make a great sustainer [cruise power plus plenty left over to charge
the batteries you used to help takeoff and climb]. 30 KW actually more than
you really would need for a E-Gull by about a factor of two.
Bruce
-
rahulchoudhary73
Re: Beetron in an eGull
Yes, maybe i should have held it back until it was actually avail able. the prototype video is a simpler version of the free piston principle with only one moving part. Most real products will have two moving parts, single combustion chamber in the centre, parts moving at 180 degrees while canceling vibration, and less valves
Those are gas filled bounce chambers for the return stroke. Gas springs are used too. Would love to find out their high lifecycle characteristics.
Wires come out of the stationary moving coil alternator. Which also acts at a starter. smaller engine, bigger alternator
Two cool things about these engines is their ability to startup in a single stroke, and long efficient strokes instead of the crankshaft bound limited stroke lengths. gas spends more time in the chamber, converts more heat to work, less heat lost to the walls, less blow down in the exhaust
amazing thing this machine runs at a 1:24 compression ratio for gasoline, which self ignites at near full speed, similar to diesel. now steam today can provide above 1:30 compression to work with... ;)
The 42% efficiency figure was actually a Toyota free piston proto type, they're all in that range and even higher
rc
Those are gas filled bounce chambers for the return stroke. Gas springs are used too. Would love to find out their high lifecycle characteristics.
Wires come out of the stationary moving coil alternator. Which also acts at a starter. smaller engine, bigger alternator
Two cool things about these engines is their ability to startup in a single stroke, and long efficient strokes instead of the crankshaft bound limited stroke lengths. gas spends more time in the chamber, converts more heat to work, less heat lost to the walls, less blow down in the exhaust
amazing thing this machine runs at a 1:24 compression ratio for gasoline, which self ignites at near full speed, similar to diesel. now steam today can provide above 1:30 compression to work with... ;)
The 42% efficiency figure was actually a Toyota free piston proto type, they're all in that range and even higher
rc
-
bruce.markle
Re: Beetron in an eGull
RC –
No need to wait for a production version to talk about it, it’s great to find out about stuff in the concept and development stage!
So if the prototype has one piston bouncing back and forth between the “head” gas springs, that explains the ends (pressure fill and monitor ports) and the pickup coil in the middle.
What I don’t get:
Where is the combustion chamber, and how many? (two intake ports in the middle of the engine, and 4 glow plugs in about the same place?)
How does the exhaust get out to the “head” stacks on the end?
Thinking that both ends must therefore be combustion chambers?
If so, how does the exhaust get ported? (spring loaded valve?)
How does the ignition happen (glow plugs look like they are just outboard of the intake port, ignition would happen as mixture goes in…)
Is there any more hard info on the prototype?
Thanks
Bruce
No need to wait for a production version to talk about it, it’s great to find out about stuff in the concept and development stage!
So if the prototype has one piston bouncing back and forth between the “head” gas springs, that explains the ends (pressure fill and monitor ports) and the pickup coil in the middle.
What I don’t get:
Where is the combustion chamber, and how many? (two intake ports in the middle of the engine, and 4 glow plugs in about the same place?)
How does the exhaust get out to the “head” stacks on the end?
Thinking that both ends must therefore be combustion chambers?
If so, how does the exhaust get ported? (spring loaded valve?)
How does the ignition happen (glow plugs look like they are just outboard of the intake port, ignition would happen as mixture goes in…)
Is there any more hard info on the prototype?
Thanks
Bruce
-
rahulchoudhary73
Re: Beetron in an eGull
There'll be a book written on it in some years, that'll explain things properly measured, like the internal combustion engines one by John B. Heywood
This prototype has two combustion chambers are near the first and third quarter of the engine's length. Some of Daniel's old rough notes are here, this site also covers the history of such engines going back the 1920s.
http://www.freikolben.ch/37401/109985.html
This two year old GM patent, 8261860, is quite in formative. there are a few dozen other patents too. (pat2pdf.org, enter the number)
what's it mean to say exhaust "gets ported"? it's a two stroke engine, the outlet valve would be an opening in the chamber wall, opened by the piston body when it nears the completion of the expansion stroke
What I don't get is the rather high 13500 strokes per minute frequency for the 5kW unit. thought it was about long efficient strokes, but this feels the stroke length maybe roughly the width of two adjacent north and south magnets on the alternator, of the ~sixteen that must be in the prototype and a high voltage thing
Cheers,
Rahul
This prototype has two combustion chambers are near the first and third quarter of the engine's length. Some of Daniel's old rough notes are here, this site also covers the history of such engines going back the 1920s.
http://www.freikolben.ch/37401/109985.html
This two year old GM patent, 8261860, is quite in formative. there are a few dozen other patents too. (pat2pdf.org, enter the number)
what's it mean to say exhaust "gets ported"? it's a two stroke engine, the outlet valve would be an opening in the chamber wall, opened by the piston body when it nears the completion of the expansion stroke
What I don't get is the rather high 13500 strokes per minute frequency for the 5kW unit. thought it was about long efficient strokes, but this feels the stroke length maybe roughly the width of two adjacent north and south magnets on the alternator, of the ~sixteen that must be in the prototype and a high voltage thing
Cheers,
Rahul
-
mkoxxy
Re: Beetron in an eGull
As much as I hate to even think about using fossil fuel where it is not
absolutely necessary, I expect battery energy density will still need 5 to
10 years to become practical for anything resembling cross-country flying.
This motor-generator may have solved the vibration issue, but I wonder how
loud it is (1:24 compression!?).
The 30kW set would be enough to launch an eGull, especially if the system
(including a full tank of fuel) turns out to be lighter than a big battery
+ charger. A 10kW version would be sufficient for cruise and save fuel.
Rather than carry a heavy battery for take-offs and go-arounds, it probably
would make more sense to carry a second motor-generator (also adds
redundancy where it counts most). The main advantages of a hybrid system
for ground vehicles are not compelling for aircraft (regenerative braking,
power leveling).
An advantage both systems share is that the energy source is discrete from
the electric motor(s), which provides flexibility to meet W&B goals.
To start this motor-generator will require energy, most likely from a
starter battery. But since it does not drive the prop directly, a
hand-crank like option may be feasible here (ideas?), and much safer than
hand-propping.
Thanks for starting this thread, Rahul!
Martin
absolutely necessary, I expect battery energy density will still need 5 to
10 years to become practical for anything resembling cross-country flying.
This motor-generator may have solved the vibration issue, but I wonder how
loud it is (1:24 compression!?).
The 30kW set would be enough to launch an eGull, especially if the system
(including a full tank of fuel) turns out to be lighter than a big battery
+ charger. A 10kW version would be sufficient for cruise and save fuel.
Rather than carry a heavy battery for take-offs and go-arounds, it probably
would make more sense to carry a second motor-generator (also adds
redundancy where it counts most). The main advantages of a hybrid system
for ground vehicles are not compelling for aircraft (regenerative braking,
power leveling).
An advantage both systems share is that the energy source is discrete from
the electric motor(s), which provides flexibility to meet W&B goals.
To start this motor-generator will require energy, most likely from a
starter battery. But since it does not drive the prop directly, a
hand-crank like option may be feasible here (ideas?), and much safer than
hand-propping.
Thanks for starting this thread, Rahul!
Martin
-
mkoxxy
Re: Beetron in an eGull
As much as I hate to even think about using fossil fuel where it is not
absolutely necessary, I expect battery energy density will still need 5 to
10 years to become practical for anything resembling cross-country flying.
This motor-generator may have solved the vibration issue, but I wonder how
loud it is (1:24 compression!?).
The 30kW set would be enough to launch an eGull, especially if the system
(including a full tank of fuel) turns out to be lighter than a big battery
+ charger. A 10kW version would be sufficient for cruise and save fuel.
Rather than carry a heavy battery for take-offs and go-arounds, it probably
would make more sense to carry a second motor-generator (also adds
redundancy where it counts most). The main advantages of a hybrid system
for ground vehicles are not compelling for aircraft (regenerative braking,
power leveling).
An advantage both systems share is that the energy source is discrete from
the electric motor(s), which provides flexibility to meet W&B goals.
To start this motor-generator will require energy, most likely from a
starter battery. But since it does not drive the prop directly, a
hand-crank like option may be feasible here (ideas?), and much safer than
hand-propping.
Thanks for starting this thread, Rahul!
absolutely necessary, I expect battery energy density will still need 5 to
10 years to become practical for anything resembling cross-country flying.
This motor-generator may have solved the vibration issue, but I wonder how
loud it is (1:24 compression!?).
The 30kW set would be enough to launch an eGull, especially if the system
(including a full tank of fuel) turns out to be lighter than a big battery
+ charger. A 10kW version would be sufficient for cruise and save fuel.
Rather than carry a heavy battery for take-offs and go-arounds, it probably
would make more sense to carry a second motor-generator (also adds
redundancy where it counts most). The main advantages of a hybrid system
for ground vehicles are not compelling for aircraft (regenerative braking,
power leveling).
An advantage both systems share is that the energy source is discrete from
the electric motor(s), which provides flexibility to meet W&B goals.
To start this motor-generator will require energy, most likely from a
starter battery. But since it does not drive the prop directly, a
hand-crank like option may be feasible here (ideas?), and much safer than
hand-propping.
Thanks for starting this thread, Rahul!
-
rahulchoudhary73
Re: Beetron in an eGull
Bruce, this is a good read on the concept and multiple R&D efforts ongoing,
http://www.mikalsen.eu/papers/FPEreview.pdf
rc
http://www.mikalsen.eu/papers/FPEreview.pdf
rc
-
rahulchoudhary73
Re: Beetron in an eGull
ought to be quieter than regular engines, exhaust seems to be at lesser pressure for this type. compressing isn't noisy, mostly poppet valves and exhaust, i guess
Martin, the Volta eGull hybrid could do a 1000miles on a tank of gas, soon i hope ;)
rc
Martin, the Volta eGull hybrid could do a 1000miles on a tank of gas, soon i hope ;)
rc