88 ms·

Raytheon completes engine run of hybrid-electric flight demonstrator

88 points by thealienthing 4y ago

snshn 4y ago
- AYBABTME 4y ago
  What about it?
this_steve_j 4y ago
The 1MW powerplant will be mounted on a De Havilland Dash 8-100 turboprop aircraft, scheduled to perform its first test flight in 2024. The engine and its technology will allow for more efficient engine performance during the different phases of flight, such as take-off, climb and cruise. The goal of the battery-electric powertrain is to reduce fuel burn and CO2 emissions by 30% compared to a standard Dash-8 turboprop. https://simpleflying.com/raytheon-completes-ground-test-dash-8-hybrid-electric-engine/ https://simpleflying.com/raytheon-completes-ground-test-dash...
- deleted 4y ago
  [deleted]
- Symmetry 4y ago
  I was wondering "why just two props" when reading this, thanks. Because they're reusing an existing airframe makes a lot of sense, even if a lot of benefits from electric airplanes come from adding more, smaller props.
  - cesaref 4y ago
    Yes exactly - I think the idea is to give a way forward for existing airframes to use more efficient engines. The fact they are hybrid is irrelevant to the owner, they just see lower running costs.
- cryptonector 4y ago
  How does the weight of the original vs. the modified compare?
mikepavone 4y ago
This and most recent articles on the demonstrator are frustratingly light on details. Found some more info on Wikipedia's article on hybrid electric aircraft [0] which cites an Aviation Week article [1] that is unfortunately behind a paywall > One 2,150 hp (1,600 kW) PW121 turboprop will be replaced by a 1 MW (1,300 hp) gas turbine joined with an electric motor of the same rating, powered by off-the-shelf lithium-ion batteries for takeoff and climb. The turbine is used alone in cruise and drives the motor-generator to recharge the batteries in descent. The downsized engine operates at its optimum for 30% fuel savings over 200–250 nmi (370–460 km). Range is reduced from 1,000 to 600 nmi (1,900 to 1,100 km) due to the higher empty weight and 50% lower fuel capacity. [0] https://en.wikipedia.org/wiki/Hybrid_electric_aircraft https://en.wikipedia.org/wiki/Hybrid_electric_aircraft [1] https://aviationweek.com/aerospace/utcs-dash-8-hybrid-electric-x-plane-targets-commercial-market https://aviationweek.com/aerospace/utcs-dash-8-hybrid-electr...
- dtgriscom 4y ago
  I've been disdaining the idea of hybrid aircraft for years, thinking there was no way to capture the energy of deceleration (as you can in a hybrid car). Here, though, the rationale is different; you're storing turbine power during descent for use at the next ascent. I wonder if you could indeed capture the deceleration energy by having the air stream drive the prop and thus the motor/generator. Planes have multiple systems for wasting energy and slowing down (flaps, air brakes, even dropping the landing gear); perhaps this wasted energy could be put into the batteries?
  - kijiki 4y ago
    Energy recovery is absolutely possible. On a smaller scale, all jet airliners have a RAT (Ram Air Turbine), which is just a propeller that drops into the airstream if both engines fail. It provides hydraulic pressure and electrical power during an emergency.
    - marvin 4y ago
      I don't understand how developing tech for energy recovery makes sense. Why not just idle and descend at a reasonable speed for a reasonable L/D, the way practically all airlines do for practically all routes today? This is energy recovery; turning your altitude into distance traversed. Hard to believe that putting a vortex-generating turbine and a generator into the airstream will improve efficiency against that.
dmitrygr 4y ago
The idea that you only need the full power for takeoff is nonsense. You also need it for go-arounds, or fighting strong downdrafts, or if you get seriously and quickly iced up and need full power to simply stay aloft, or if your engine #1 goes out and you need to add power on #2.... Check how MANY checklists for how many situations require full power. Maybe this has applications for unmanned stuff where it is ok to lose the craft sometimes (which explains Raytheon's interest) but for human carrying, this is idiocy, i say again.
- hcknwscommenter 4y ago
  I think you misunderstand. The largest use-case for full-power is takeoff, and that is where the most energy savings comes from having an electric motor assist during the full-power need. That does not mean that full-power would be unavailable for those other uses you mention.
  - progman32 4y ago
    The batteries are recharged during descent, if I understand correctly. Since "full power" in this craft requires the lithium batteries to be charged, I wonder how much reserve energy will be left in those during cruise for contingency reasons. Perhaps there is plenty left for fighting downdrafts, etc. Unsure. One nice thing about electric motors is that they can be "throttled up" almost instantaneously, unlike some (not all) turbines. For example, that ultra fast response may be useful in a wind shear situation.
  - ngcc_hk 4y ago
    But if the battery is not in ideal state like just after climb up, would that be a problem as the real full power is not really available all the time it seemed.
alwaysanagenda 4y ago
how large can you scale electric airplanes with hyper-dense battery cells? I would imagine hitting the weight limit of traditional aircraft very quickly to get the same output of power. oil's energy per square inch still can't be beat.
- colechristensen 4y ago
  It boils down to getting less range for a given payload for any given aircraft. You can exchange less payload for more range until you have nothing but pilots. It seems to get equivalent power you need to either exchange a third or so of your range or a significant portion of cargo or a mixture of both. Hydrocarbons do indeed have significantly more energy density and the benefit that once you’ve used them the weight of the fuel goes away giving you less work to do as your fuel runs out.
Symmetry 4y ago
It seems that for militaries without the budget for helicopters or real tiltrotors like the Osprey a hybrid electric quad tiltroter as a replacement. There are a lot of drawbacks, of course, but I'd think the ease of maintenance and ease of training relative to a real helicopter would be a powerful argument for some countries.

88 points by thealienthing 4y ago

AYBABTME 4y ago
What about it?

The 1MW powerplant will be mounted on a De Havilland Dash 8-100 turboprop aircraft, scheduled to perform its first test flight in 2024. The engine and its technology will allow for more efficient engine performance during the different phases of flight, such as take-off, climb and cruise. The goal of the battery-electric powertrain is to reduce fuel burn and CO2 emissions by 30% compared to a standard Dash-8 turboprop. https://simpleflying.com/raytheon-completes-ground-test-dash-8-hybrid-electric-engine/ https://simpleflying.com/raytheon-completes-ground-test-dash...

deleted 4y ago
[deleted]
Symmetry 4y ago
I was wondering "why just two props" when reading this, thanks. Because they're reusing an existing airframe makes a lot of sense, even if a lot of benefits from electric airplanes come from adding more, smaller props.
- cesaref 4y ago
  Yes exactly - I think the idea is to give a way forward for existing airframes to use more efficient engines. The fact they are hybrid is irrelevant to the owner, they just see lower running costs.
cryptonector 4y ago
How does the weight of the original vs. the modified compare?

mikepavone 4y ago

This and most recent articles on the demonstrator are frustratingly light on details. Found some more info on Wikipedia's article on hybrid electric aircraft [0] which cites an Aviation Week article [1] that is unfortunately behind a paywall > One 2,150 hp (1,600 kW) PW121 turboprop will be replaced by a 1 MW (1,300 hp) gas turbine joined with an electric motor of the same rating, powered by off-the-shelf lithium-ion batteries for takeoff and climb. The turbine is used alone in cruise and drives the motor-generator to recharge the batteries in descent. The downsized engine operates at its optimum for 30% fuel savings over 200–250 nmi (370–460 km). Range is reduced from 1,000 to 600 nmi (1,900 to 1,100 km) due to the higher empty weight and 50% lower fuel capacity. [0] https://en.wikipedia.org/wiki/Hybrid_electric_aircraft https://en.wikipedia.org/wiki/Hybrid_electric_aircraft [1] https://aviationweek.com/aerospace/utcs-dash-8-hybrid-electric-x-plane-targets-commercial-market https://aviationweek.com/aerospace/utcs-dash-8-hybrid-electr...

dtgriscom 4y ago
I've been disdaining the idea of hybrid aircraft for years, thinking there was no way to capture the energy of deceleration (as you can in a hybrid car). Here, though, the rationale is different; you're storing turbine power during descent for use at the next ascent. I wonder if you could indeed capture the deceleration energy by having the air stream drive the prop and thus the motor/generator. Planes have multiple systems for wasting energy and slowing down (flaps, air brakes, even dropping the landing gear); perhaps this wasted energy could be put into the batteries?
- kijiki 4y ago
  Energy recovery is absolutely possible. On a smaller scale, all jet airliners have a RAT (Ram Air Turbine), which is just a propeller that drops into the airstream if both engines fail. It provides hydraulic pressure and electrical power during an emergency.
  - marvin 4y ago
    I don't understand how developing tech for energy recovery makes sense. Why not just idle and descend at a reasonable speed for a reasonable L/D, the way practically all airlines do for practically all routes today? This is energy recovery; turning your altitude into distance traversed. Hard to believe that putting a vortex-generating turbine and a generator into the airstream will improve efficiency against that.

dmitrygr 4y ago

The idea that you only need the full power for takeoff is nonsense. You also need it for go-arounds, or fighting strong downdrafts, or if you get seriously and quickly iced up and need full power to simply stay aloft, or if your engine #1 goes out and you need to add power on #2.... Check how MANY checklists for how many situations require full power. Maybe this has applications for unmanned stuff where it is ok to lose the craft sometimes (which explains Raytheon's interest) but for human carrying, this is idiocy, i say again.

hcknwscommenter 4y ago
I think you misunderstand. The largest use-case for full-power is takeoff, and that is where the most energy savings comes from having an electric motor assist during the full-power need. That does not mean that full-power would be unavailable for those other uses you mention.
- progman32 4y ago
  The batteries are recharged during descent, if I understand correctly. Since "full power" in this craft requires the lithium batteries to be charged, I wonder how much reserve energy will be left in those during cruise for contingency reasons. Perhaps there is plenty left for fighting downdrafts, etc. Unsure. One nice thing about electric motors is that they can be "throttled up" almost instantaneously, unlike some (not all) turbines. For example, that ultra fast response may be useful in a wind shear situation.
- ngcc_hk 4y ago
  But if the battery is not in ideal state like just after climb up, would that be a problem as the real full power is not really available all the time it seemed.

alwaysanagenda 4y ago

how large can you scale electric airplanes with hyper-dense battery cells? I would imagine hitting the weight limit of traditional aircraft very quickly to get the same output of power. oil's energy per square inch still can't be beat.

colechristensen 4y ago
It boils down to getting less range for a given payload for any given aircraft. You can exchange less payload for more range until you have nothing but pilots. It seems to get equivalent power you need to either exchange a third or so of your range or a significant portion of cargo or a mixture of both. Hydrocarbons do indeed have significantly more energy density and the benefit that once you’ve used them the weight of the fuel goes away giving you less work to do as your fuel runs out.

Symmetry 4y ago

It seems that for militaries without the budget for helicopters or real tiltrotors like the Osprey a hybrid electric quad tiltroter as a replacement. There are a lot of drawbacks, of course, but I'd think the ease of maintenance and ease of training relative to a real helicopter would be a powerful argument for some countries.