Honeywell Debuts Hybrid-Electric Turbine Engine

Honeywell Aerospace's hybrid-electric turbogenerator that will power the first generation of vertical takeoff and landing (VTOL) aircraft will make its public debut early next month at Heli-Expo, the Phoenix-based company announced today. The hybrid powerplant is an electrified version of its 1,100-shp HTS900 gas turbine engine used on Kopter's SH09 light turbine helicopter and Eagle Copters' Eagle 407HP conversion.
"In regards to urban air mobility, that's really the sweet spot [for shaft horsepower]," Bryan Wood, who runs the hybrid propulsion division for Honeywell Aerospace's engines and power systems group, told AIN. "This is an engine that we've decided to highlight. It has a very competitive power density and specific fuel consumption."
A gearbox mounted to the HTS900 drives a pair of 200-kilowatt generators, Wood said. "We're actually able to produce power from the engine, which then feeds into the generators, which will then downstream spin motors," he said. The generators' output is enough to power 40 average American homes running air conditioners at their highest setting, Honeywell said.
In tandem with batteries, the hybrid will produce 30 to 50 percent fewer carbon emissions than the traditional HTS900 engine. XTI's TriFan 600 is the first airframe where the turbogenerator will be used, though Wood added there are "other customers as well that we're very engaged in conversation with" about using it.

Cool.....but, while the technology is exciting, and I don't want to sound like a Luddite.
1. Can batteries be "swapped" for fuel, or are they dead weight when not being used?
2. How is charging accommodated to prevent Li-Ion fires?
3. Cold Wx performance of batteries?
4. Battery replacement costs?
5. How is OEI impacted by battery condition/Is OEI possible without the battery? (There maybe some potential certification issues here. Do you certify at 80% battery efficiency knowing that batteries degrade over time? Or certify at a higher percentage of efficiency and mandate a lower forced removal time?

Assuming no batteries are used? There could be several advantages. (These don't go away with batteries either.)
1. No more gearboxes
2. No more driveshafts
3. Possibly more flexibility with the location of the engine(s) (See #1 and #2.)

This will be fun to watch.

jetcal1 said:

Cool.....but, while the technology is exciting, and I don't want to sound like a Luddite.
1. Can batteries be "swapped" for fuel, or are they dead weight when not being used?
2. How is charging accommodated to prevent Li-Ion fires?
3. Cold Wx performance of batteries?
4. Battery replacement costs?
5. How is OEI impacted by battery condition/Is OEI possible without the battery? (There maybe some potential certification issues here. Do you certify at 80% battery efficiency knowing that batteries degrade over time? Or certify at a higher percentage of efficiency and mandate a lower forced removal time?

Assuming no batteries are used? There could be several advantages. (These don't go away with batteries either.)
1. No more gearboxes
2. No more driveshafts
3. Possibly more flexibility with the location of the engine(s) (See #1 and #2.)

This will be fun to watch.

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NiCd batteries already require monitoring for heat and charge rate, so I don't think there will be a huge change as far as monitoring goes. As far as I understand it, the charge control is more complicated, but the operating environment of a helicopter is closer to that of a car than an airliner is.
Battery replacement costs would be more than offset by the lack of gearboxes to overhaul (those things are expensive!)
OEI operation is most critical at take-off and hover, so there may well be time limits which come into effect.

Someone built a UAV several years ago that seemed to be the way to go. It had wings with built in fans for vertical lift. Batteries were recharged during horizontal flight and then on landing and takeoff the fans went into operation to provide VTOL capability. That way the batteries did not have to be too large, since they were only used during landing and takeoff.

The way that hybrid autos work (not plug-in hybrids) is that the electric motor is only used for added boost during acceleration. The otherwise wimpy engine can't handle it all so the electric motor is used like an "afterburner."

But it looks like this Honeywell engine (note, Honeywell bought Garrett AirResearch decades ago, so it is not the guys who built your home thermostat) is designed to power nothing but electric motors for propulsion. Presumably the batteries will be used to augment the engine's output. Probably during descent the motors will recharge the batteries as well. Swapping out the batteries will only be done as a maintenance procedure, when they get worn out. On the TriFan 600 they have two wing mounted motors that rotate like V-22 engines do with a third motor in the fuselage just used for VTOL.

Kerosene represents an "energy storage" method that is over 1000 times more efficient in terms of energy/lb than the best batteries we currently have.

MIflyer said:

...
A gearbox mounted to the HTS900 drives a pair of 200-kilowatt generators, Wood said. "We're actually able to produce power from the engine, which then feeds into the generators, which will then downstream spin motors," he said.
...

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I'm always left flabergasted when people actually produce power from an engine, especially in 21st century.

gumbyk said:

NiCd batteries already require monitoring for heat and charge rate, so I don't think there will be a huge change as far as monitoring goes. As far as I understand it, the charge control is more complicated, but the operating environment of a helicopter is closer to that of a car than an airliner is.
Battery replacement costs would be more than offset by the lack of gearboxes to overhaul (those things are expensive!)
OEI operation is most critical at take-off and hover, so there may well be time limits which come into effect.

Click to expand...

Never underestimate the ability of the FAA to drive up the certification costs! I have to wonder what the production break-even point will be after the FAA is done with imposing novel certification requirements for a new species of equipment. I don't know about gearbox weight. Even on our H-53 only the main gearbox was cumbersome to R&R. The intermediate and T/R were actually pretty light. I have to wonder how much weight savings will actually acrue from removing them versus the weight of the batteries and the (I can almost guarantee) weight of the FAA mandated fire suppression system.

jetcal1 said:

Never underestimate the ability of the FAA to drive up the certification costs! I have to wonder what the production break-even point will be after the FAA is done with imposing novel certification requirements for a new species of equipment. I don't know about gearbox weight. Even on our H-53 only the main gearbox was cumbersome to R&R. The intermediate and T/R were actually pretty light. I have to wonder how much weight savings will actually acrue from removing them versus the weight of the batteries and the (I can almost guarantee) weight of the FAA mandated fire suppression system.

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Well, to be honest, the FAA have been stung already trying to keep certification costs down (remember the 787?), so I'd expect them to be cautious, especially as the battery makes up part of the propulsion system.
Even if it doesn't result in any weight savings, the maintenance cost savings should be significant. We were budgeting over $100 USD per hour for a MGB overhaul/lifed component replacement on a BK-117/EC-145. TGB and IGB were $30 each per hour. Remove them and you've got significant savings.
With fewer rotating components (no drive-shafts) and variable speed rotors it will make for a more comfortable ride too.

I'm cautiously optimistic. I remember the problems getting the Bellanca Skyrocket, AJI Hustler and the Learfan certified back in the day. And honestly, I don't think it's gotten better for cutting edge to get certified over the last 40 years.

gumbyk said:

Well, to be honest, the FAA have been stung already trying to keep certification costs down (remember the 787?)

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Enjoy. And please notice the publication date.

I have worked as an FAA contractor. They said their motto is:

"We're not happy until you're not happy."

MIflyer said:

I have worked as an FAA contractor. They said their motto is:

"We're not happy until you're not happy."

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- The gentleman writing/revising TSO in DC, "I don't know, I'll have to ask someone who knows about airplanes".
- My two PI's arguing in front of me over the format of my manuals after the 4th rewrite. (And I thought it was me.)
Having said that, 99.9999% of the time I really didn't mind having them in the hangar.