[HN Gopher] Raytheon completes engine run of hybrid-electric fli...
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Raytheon completes engine run of hybrid-electric flight
demonstrator
Author : thealienthing
Score : 71 points
Date : 2022-12-21 16:11 UTC (6 hours ago)
(HTM) web link (www.timesaerospace.aero)
(TXT) w3m dump (www.timesaerospace.aero)
| this_steve_j wrote:
| 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...
| Symmetry wrote:
| 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 wrote:
| 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.
| [deleted]
| mikepavone wrote:
| 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
|
| [1] https://aviationweek.com/aerospace/utcs-dash-8-hybrid-
| electr...
| DSingularity wrote:
| Loss in range? What's the point now?
| 908B64B197 wrote:
| These prop airplanes are used for flights nowhere near close
| to the airplane's maximum range (although most major airlines
| are retiring them).
| tempest_ wrote:
| 30% fuel savings on short haul trips less than whatever 60%
| of the standard range would be.
| dtgriscom wrote:
| 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 wrote:
| 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 wrote:
| 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.
| hedgehog wrote:
| I don't think that's what the Raytheon prototype is
| doing. It sounds like they're capturing some of the
| mechanical energy from the engine during descent and
| putting that into the battery for later use. Hybrid cars
| do that, when the driver requests an amount of power too
| far from the most efficient band they make up the
| difference by charging/discharging the battery. Knowing
| the target usage lets the engineers make more aggressive
| tradeoffs to optimize efficiency for that band.
| VBprogrammer wrote:
| When they handle the low hanging fruit of having an electric
| motor to propel the aircraft from the gate to the runway
| (bonus points for being able to pushback under their own
| power) it might become worth while.
| kube-system wrote:
| Well, part of the reason you start them at the gate is also
| to test them and warm them up before you get to the most
| critical part of the flight where you absolutely need to be
| sure they're going to run: takeoff and initial climb. You
| don't want to be doing that procedure on the runway for
| operational reasons.
|
| And some airplanes are already capable of pushing back
| under their own power. The reason we don't do that is not
| the plane -- it's the airport. The blast can damage the
| airport, ground equipment, and endanger people.
| LarryMullins wrote:
| > _The turbine is used alone in cruise_
|
| If I understand this right, they're still driving the prop
| mechanically through a gearbox during cruise, rather than using
| turbo-electric transmission?
| mikepavone wrote:
| That's my understanding. Given that the turbine is used in
| parallel during takeoff/climb and drives the electric motor
| as a generator during descent (while presumably still driving
| the prop) there would need to be a mechanical linkage. Since
| the linkage is already there, you wouldn't save on weight by
| using a serial hybrid setup for cruise and the turbine is
| already sized to be running in an efficient power band for
| cruise flight.
| [deleted]
| Symmetry wrote:
| 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.
| dmitrygr wrote:
| 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 wrote:
| 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 wrote:
| 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.
| snshn wrote:
| AYBABTME wrote:
| What about it?
| alwaysanagenda wrote:
| 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 wrote:
| 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.
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(page generated 2022-12-21 23:01 UTC)