Attachment 0002
March 3, 2020 EPS RFI Industry Days
Electrical System Architecture
What is the Army/logic for a 270DC volt system?
o Theres been a commercial push for higher voltage architecture systems. The
Army cannot foresee a future given future advancements in systems and
capabilities where the Army would not want to migrate to a 270DC volt system.
270dc starter generator, are the maximum engine accessory drag torque curves
available for the planned applications? What power source should be assumed available
for ground starting? For in air restart?
o We would be targeting enduring fleet platforms initially with future plans for
FVL. Specific torque curves will not be presented during the RFI process. Ground
start will be from onboard power (battery/onboard APU/etc) and AGPU. In air
restart can be facilitated via battery in the event of an electrical starter
generator is used or via the onboard APU.
Is the Army intent to eventually acquire entire systems/subsystems from a single
integrator or provider? Separate from air vehicle?
o The decision has not been made at this time.
Power and Thermal Management
Are you targeting higher than 270DC v. What is driving the trend? Where will the
additional power be applied? Propulsion only? More electrification of pneumatic and
hydraulic systems? Reduce weight of aircraft? What challenges are you experiencing
with the higher voltage? What challenges do you see with wiring, connectors, etc? Do
you see issues with EMI Shielding? Can you elaborate? Do you see issue with partial
discharge?
o 270 is the target if feasible on enduring fleet but Army will consider more. The
future of aviation is driving demand. Army aiming to reduce weight while gaining
the benefit of a more electric aircraft. The main challenge with going to a higher
voltage is electrical arcing at the altitude and Army airworthiness qual. There is
also the interim problem of the transition and the weight impacts to the
enduring fleet. Most systems are AC currently. To run 270DCV from the main
generators will require heavy inverters given Armys understanding of the
current state of the art equipment.
Airworthiness and certification, earlier you mentioned the commercial push to going to
270V. Will there be a similar push from commercial/civil cert requirement on
software/hardware (178C, 254, etc)?
Attachment 0002
o Depending on the criticality, software will be pushed to the proper DO-178C
requirement. Hardware specifications that are important to the Army are 810,
704, and 46.
Will a list of participants interested in partnering be distributed? DuPont has developed
a new family of thermally conductive and electrically insulative films and laminates that
may be interesting to companies concerned with power and thermal management
issues
o We will not provide a list of attendees for this industry day.
Are there requirements for cabin pressurization for any of the referenced platforms?
o For Army rotorwing and UAS there is no pressurization requirement. For Army
fixed wing there is a pressurization requirement.
APU/SPU
hydraulically?
Batteries
What is the capability of the current APU? Is the intent to start the APU electrically or
o Depending on platform the generator attached to the APU provides 20-30KVA of
110AC electrical power. The Army has no preference.
Are lithium ion batteries the preferred solution?
o The Army has is currently looking at lithium ion, but is not excluding other
chemistries from future selection. The Army is looking for any battery solution
that can pass current Army MILSPECs and also be ballistically tolerant.
Are there no size restrictions provided? What is the minimum acceptable power/weight
ratio for each battery?
o Currently the Army only utilizes batteries for emergency power and APU start.
The Army currently has an ongoing project to replace the SLAB/FNC emergency
batteries in army rotorcraft. As it pertains to this RFI, the Army is not restricting
battery solutions to a specific power to weight ratio or size.
Are there plans to use this battery for other tasks other than the current on of
emergency power and APU start?
o Yes. The Army is hoping that this RFI will provide additional information on novel
ways to further utilize batteries on Army platforms for such activities as power
conditioning, power management, surge capability, high energy systems, etc.
Main Generators (we had technical difficulties with the internet for 15-20 minutes during this
section, but no questions)
Attachment 0002
Starter-Generators
What are some design changes, if any, are you considering for the main generator to run
270VDC? What challenges do you anticipate?
o The Army would like to be as minimally invasive as possible in regards to changes
to army platforms when upgrading main generators. The Army would expect
that the 270VDC generator would be in a similar form factor as the 115VAC
generator. The main challenge is developing a low impact architecture solution
that can be qualified under Army Aviation qualification standards.
Power Electronics
Will thermal management be an issue with the power electronics? How so?
o That is application specific. Given that the Army currently uses inefficient power
electronics, there is a lot of energy wasted in the form of heat. The Army is
hoping to capitalize off of modern power electronic systems that have greater
efficiencies. The Army also sees more energy demands coming to the aircrafts.
There will be a point in the future where additional thermal management for
power electronics will be necessary.
Are materials that dissipate heat something you would consider? Maybe you are already
considering such options? If so, what options are potentially viable?
o From a system level, the Army already sees heat dissipation material used. The
Army does see novel modern heat dissipation materials and systems being
utilized in the future for high energy demand applications. The Army has no
guidance for a preferred solution, rather the Army expects the vendors for the
individual Line Replacement Units (LRU) to design the optimal solutions and
present thermal solution merits.
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