N231-053 TITLE: Improved Electromechanical Actuators for Aircraft Carrier Flight Deck Applications
OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): General Warfighting Requirements (GWR)
OBJECTIVE: Improve the existing configuration of Electromechanical Actuators (EMAs) to lower in a safe, controlled manner in the event of a system or component failure for Aircraft Carrier flight deck applications.
DESCRIPTION: Aircraft Launch and Recovery (ALRE) is a critical part of aircraft carrier flight deck operation as the carrier aviation depends on the system for launching and landing aircrafts during flight deck operations. ALRE includes Jet Blast Deflectors (JBDs), Integrated Catapult Control System (ICCS), Barricade Stanchions, and Landing Signal Officer Display Systems (LSODS) , which utilize EMAs as the mechanism to raise and lower the operative components.
EMAs are an alternative to hydraulic actuators, which require which require multiple hydraulic pumps that require pumps, pipes, and valves and lead to fluid contamination, oil leakage, or fire due to hot breaks. EMAs convert electricity to motive force. The force created can be used to move large doors, operate switches for sorting conveyor systems, or move powered valves. Commercially EMAs are used in platforms such as landing gear, steering actuation, doors, brakes, and primary and secondary flight controls.
In the Navy, EMAs are used extensively on the CVN78 flight decks to raise and lower JBDs, Integrated ICCS, Barricade Stanchions, and LSODS. Existing EMAs are unable to lower in the event of mechanical or select electrical failures, creating a risk to flight deck operations, including loss of aircraft. JBD unit number three (3) poses the greatest risk to emergency flight recovery operations, which elevates the focus to develop a solution specific to this location. However, the need to improve reliability and reduce maintenance requirements persists for all flight deck EMA applications. The existing EMAs that actuate the JBDs are ineffective at lowering in the event of system or component failure, which poses significant risk to emergency aircraft recovery. There have been several documented cases of prevented JBD panel lowering incidents on aircraft carriers and successful outcome of this project is considered critical in support of carrier flight operations and in direct support of mission readiness. The current EMA applications, specifically on JBD 3, creates a critical need for a solution for an improved EMA that will lower in a safe, controlled manner in the event of a system or component failure.
During aircraft carrier launch operations, the JBD functions as a physical safety barrier between the aircraft engine-nozzle exhaust and any equipment or personnel that are located behind the aircraft. A JBD is installed directly aft of each catapult and consists of either four or six aluminum panels. These panels raise from the flight deck and, in operational position, divert the aircraft�s jet blast upward. The panels become an integral part of the flight deck surface when lowered to their stowed position. The focus of this SBIR topic is to improve the current EMAs that actuate JBDs for safe and rapid manually-controlled lowering capability during emergency operations due to system or component failure. This action would ideally occur remotely, however, if a proposed solution occurs locally, then the time to deploy and activate the lowering action will be a major evaluation factor in meeting the time requirement.
The JBD actuators exist in a severe environment where frequent exposure to seawater, jet fuel, grease, and other debris, and includes periods of submersion from accumulation of these elements. The JBD must remain raised if there is a loss of normal operating power and emergency lowering must commence upon manual control only. The physical space is highly constrained due to their proximity to other ship structure, systems, and components. The existing space dimensions are 14L x 36W x 1.8H feet with an approximate volume of 600 square feet occupied by in-situ machinery.
Below are the requirements and technical data for JBDs.
Dimensions: 6 feet wide with six (6) panels operating simultaneously in adjacent series along the length dimension at 14 feet and raised to a height of 10.7 on the aft arrangement. They raise simultaneously to an angle of 50 degrees from a horizontal position relative to the flight deck.
Weight of Existing Panel: 5,200 lbs.
Static Force (needed to overcome the weight of each panel): 38,000 lbs.
Time to Lower (in the event of system or component failure):not more than 12 minutes.
Method of Lowering: initiated manually, either remotely or locally.
Safety Risks: must not pose any human-machine interface safety risks.
NOTE: Technologies that achieve fully-lowered JBDs in the safest manner, which could entail remote operation, and in the shortest time will receive evaluation preference. Technologies that introduce the least time consuming maintenance requirements will also receive evaluation preference.
The current design employs a mechanical clutch that disengages the EMA from the actuator and a mechanical brake that controls the descent rate of the JBD lowering action. Consideration should be given for alternative technologies that effect a manually-controlled emergency lowering operation such as locally or remotely controlled electro-hydraulics, pneumatics or other compressed gas cylinders and rams; coil springs; electro-magnetic cushioning; or any other novel dynamic control technologies, devices, or materials, or any configurations thereof that would integrate any existing means for lowering large heavy hinged objects in a rapid and safe manner under manually-controlled operation. Further consideration could also be given to effect a cascading action by leveraging raised panels as resistance in lowering adjacent panels in subsequence, thereby limiting the power demands to the final remaining upright panel.
PHASE I: Develop a concept for improved EMAs for Aircraft Carrier Flight Deck applications that meet the requirements in the Description. Demonstrate the feasibility of the concept in meeting Navy needs and establish that the concept can be developed into a useful product for the Navy. Feasibility of the electromechanical actuator will be established via computer modeling. The Phase I Option, if exercised, will include the initial design specifications and capabilities description to build a prototype solution in Phase II.
PHASE II: Develop and deliver a prototype and demonstrate that it can meet the needs of the Navy. Initial testing of the system will be on subscale demonstrators progressing to full-scale system testing at a location and facility to be determined. Testing must demonstrate performance, environmental robustness, shipboard shock and vibration, and maintainability. Product performance will be demonstrated through prototype evaluation, modeling, and demonstration over the required range of parameters. An extended test in a maritime environment will be used to refine the prototype into a design that will meet Navy requirements. Prepare a Phase III manufacturing and development plan to transition the electromechanical actuators to Navy use.
PHASE III DUAL USE APPLICATIONS: Support the Navy in transitioning the EMAs to Navy use. Manufacture and install, on a candidate Gerald R. Ford and Nimitz Class aircraft carrier, one EMA system for shipboard test and evaluation. Plan to produce units for forward fit to CVN-81 and follow, and back-fit of the entire class of in-service carriers.
Improved speed, precision, movement, and manual override to EMAs can be a substitute in any format or industry where this technology is currently being utilized such as mechanical systems, industrial machinery, computer peripherals, printers, opening and closing dampers, locking doors, braking machine motions, 3d printers, and commercial aircraft manufacturing.
REFERENCES:
1. McGee, Tim & Johnson, Warren "Advances achieved from use of Electromechanical Actuators for the FORD-Class carrier�s Jet Blast Deflectors." Curtiss-Wright. American Society Naval Engineers. April 2019, navysbir.com/n23_1/N231-053_Reference_1_CW.pdf
2. Kovnat, Alexander R., "Electromechanical Actuators for Active Suspension Systems". U.S. Army Tank-Automotive Research, Development and Engineering Center, November 1996, navysbir.com/n23_1/N231-053_Reference_2_Electromechanical.pdf
KEYWORDS: Aircraft Carriers; Electromechanical Actuators;; Aircraft Launch and Recovery;; Jet Blast Deflectors;; Flight Deck operations; Emergency Lowering of JBDs.
** TOPIC NOTICE ** |
The Navy Topic above is an "unofficial" copy from the Navy Topics in the DoD 23.1 SBIR BAA. Please see the official DoD Topic website at www.defensesbirsttr.mil/SBIR-STTR/Opportunities/#announcements for any updates. The DoD issued its Navy 23.1 SBIR Topics pre-release on January 11, 2023 which opens to receive proposals on February 8, 2023, and closes March 8, 2023 (12:00pm ET). Direct Contact with Topic Authors: During the pre-release period (January 11, 2023 thru February 7, 2023) proposing firms have an opportunity to directly contact the Technical Point of Contact (TPOC) to ask technical questions about the specific BAA topic. Once DoD begins accepting proposals on February 8, 2023 no further direct contact between proposers and topic authors is allowed unless the Topic Author is responding to a question submitted during the Pre-release period. SITIS Q&A System: After the pre-release period, and until February 22, 2023, (at 12:00 PM ET), proposers may submit written questions through SITIS (SBIR/STTR Interactive Topic Information System) at www.dodsbirsttr.mil/topics-app/, login and follow instructions. In SITIS, the questioner and respondent remain anonymous but all questions and answers are posted for general viewing. Topics Search Engine: Visit the DoD Topic Search Tool at www.dodsbirsttr.mil/topics-app/ to find topics by keyword across all DoD Components participating in this BAA.
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| 2/9/23 | Q. | 1. What are the voltage, current and power capabilities of the existing Portable Power Supply (PPS)?
2. Could the EMA enhancement be continuously plugged into the PPS, such that it is powered in an emergency state? Or will any equipment relying on the PPS need to be plugged in only when it is time to use it? 3. There was no mention of output position sensing in the previous answers. Does the current system measure actuator output position and/or panel angle? What type of device is it? If there is no position sensor, how does the system ensure it starts and stops at the correct panel position? 4. In the force plot provided there are three lines: minimum, average, and maximum actuator force. Are these plots of existing actuator capability, or plots of required actuator capability? The solicitation states static force required of 38,000 lbf, but the maximum force plot well exceeds that value. Can you clarify how the provided force plot and stated 38,000 lbf relate to each other? 5. The solicitation states that JBD#3 is most in need of a solution. However, the descriptions in the Q&A about the hydraulic clutch/brake assembly used in this location make it sound like that JBD#3 is easier to lower then other locations requiring use of a tow truck. Can you provide more information about what is undesirable about the hydraulic clutch & brake system used on JBD#3? 6. It was stated that some of the existing actuators are experiencing higher than anticipated backdrive forces. In these instances, is there still a panel position that exists where the weight of the panel will reliably backdrive the actuator? Or is the required backdriving force so high that additional external loads must be applied to move the system? |
| A. | 1. 24VDC, 40A, 12Ah
2. In current design, PPS is used in an emergency situation or during routine training. In normal condition, PPS is stowed away and plugged into its charging station. 3. Position sensing is done via feedback from actuator motor resolver and processed by the VFD resolver card. 4. Provided plots describe required load profile for actuators (existing actuators meet these profiles). The 38,000lbs is approx. the maximum force encountered at 20 degrees of the deck in the minimum load profile (red). The actuator normal load profile is expected to meet or exceed that force at that angle. 5. The hydraulic clutch & brake system used on JBD#3 is operating as expected. However, it is a complex design that required significant number of people to operate in order to meet the 12 minute requirement. Additionally, it utilizes two hydraulic skids that barely fit in the equipment room and introduces additional complex maintenance action. 6. Some actuators exhibit 3x higher than normal back drive forces which prevent their associated panels to lower by gravity during E-lowering. Backdrive issues are being investigated by OEM |
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| 2/7/23 | Q. | 1. Does the equipment room span the entire length of the JBD doors so that all operating gear cams can be feasibly accessed from the equipment room below?
2. What is the distance of vertical separation between the floor onto which EMA is mounted and the ceiling of the equipment room below? 3. Is there sufficient space in this room to permanently accommodate a battery based power supply that is continually maintained w/ a charge under normal electrical conditions? 4. Is there a feature on either the clutch or brake that nudges the operating gear over center in order to initiate the retract process? Or do you need to drive the lower arm from the deck with the external mechanism (forgot the name of this tool). 5. Can a plot of crank shaft torque (due to weight of door) vs. crank angle be provided? If not, the crank angle at which gravity can reliably lower the door will be next best 6. Can you confirm that the mechanism goes 'over center' at 120 deg and will exert a force to extend the EMA? 7. Do you have a force plot of the reverse motion - or force required to backdrive? 8. Did the original specifications call for the clutch to disengage the EMA from the linkage and the mechanical brake (coupled directly to the electric motor?). 9. Are these EMAs failing during normal carrier operations or during stress tests? 10. Does the 2-arm linkage "lock out", and support the entire weight of a panel when the EMA is fully extended? 11. Is it correct to assume that the 38,000 lbf specification represents the maximum linear force required of the EMA? Do you have a force/load vs. stroke profile available? 12. What is the maximum stroke of the EMA? Is this a ball screw, roller screw, or lead screw? 13. Can general details on the motor, driver, and any state feedback be provided? |
| A. | 1. No. Although located in the deck right below the flight deck and below their corresponding JBD, the operating gears (EMAs, crankshaft, crank arm, linkages) are not accessible from the equipment rooms. The equipment rooms contain the electrical control panel and other control equipment.
2. The vertical distance would be the thickness of the deck (do not know that value). The EMAs are on the flight deck and the equipment rooms are in the next deck below. 3. There is already a Portable Power Supply (PPS) that is continually maintained w/ a charge under normal electrical conditions in the equipment room. 4. For JBD 1, 2 & 4 (no hydraulic clutch-brake system), a tow truck is used to push a towbar connected to the linkage while the EMA brake is pulsed with the PPS. Once the linkages are unlocked from over-center then the towbar is removed and gravity takes over while the pulsing of the brake controls the decent. For JBD 3 (with hydraulic clutch-brake system), once the clutch is disengaged, the hydraulic brake is used to unlock the linkages and then gravity takes over while the hydraulic brake controls the decent. 5. From the EMA force plot provided a guess is that it is 110 deg, but that's just a guess. Unfortunately we do not have crank shaft torque (due to weight of door) vs. crank angle. Recommend to refer to the panel load vs crank angle plot. 6. The linkages lock in over center when crank arm angle is at around 120 deg from deck, as seen in the plot. Note that the crank arm angle is at 50 deg from deck when the panel is lowered and travel counter clockwise during raise (actuator rod extends during raise). 7. No. All backdrive related data were provided by the Ship builder from their vendor and cannot be released. 8. Not completely understanding this question but the JBD3 hydraulic brake is not coupled with the electric motor. JBD3 current solution involve a hydraulic powered clutch and brake system that disengages the EMA actuator from the crank shaft and controls the panel free fall by the brake. 9. The main issue with the current EMAs is reliability during emergency lowering of the JBD panels. The issue has been narrowed down to actuator back drivability problems. Tests conducted so far revealed high back drive forces on multiple actuators. 10. Yes 11. See actuator force profile in this link - navysbir.com/n23_1/N231-053-Actuator_Force.pdf 12. Current EMA stroke is about 18-20 inches and is based on roller screw technology. 13. Actuator motor is a 720 VDC (peak) 460 VRMS, permanent magnet with resolver for feedback. Motor direction, velocity and position are controlled by a Variable Frequency drive in a PLC control system |
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| 2/7/23 | Q. | 1. Are the roller screws on the actuators inverted (rollers are inside the nut/tube)?
2. What is the approximate clearance around the actuators? 3. When an actuator requires excessive force to retract it, does the repair require replacement of the roller screw? |
| A. | 1. The roller screw technology used in our actuators has not been released by the OEM.
2. See dimensioned drawing of the area surrounding the actuator in this link - navysbir.com/n23_1/N231-053-Area_Surrounding.pdf 3. In similar situation, repair will depend on results from troubleshooting or root cause analysis. If troubleshooting reveals roller screw issues, the actuator will be overhauled to the OEM for repair. |
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| 1/20/23 | Q. | What is the current method of manual lowering? |
| A. | For JBD3, a hydraulic powered clutch and brake system is installed such that, during EMA failure, the clutch decouples the EMA from the panel linkage and the brake controls the decent. For the other JBDs: when a panel is raised, the linkage mechanically locks itself over-center. In normal operation the EMA provides the necessary torque to unlock the linkage and lower the panel. In emergency operation the method used to backdrive the EMA(s) is to use a tractor with a pushbar (1) that is placed on the JBD linkage (2) to push the panel over center to allow gravity and the EMA brake pulsing to lower the panel to the deck. |
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| 1/20/23 | Q. | Do you have a CAD model or a dimensioned drawing of the current layout for stroke, volume, swap? Assuming it's a linkage mechanism it might be worth proposing a unit that can be incorporated directly into the existing attachment points. |
| A. | Dimensioned drawing cannot be released at this time but will later be included in this Q&A section. Actuator stroke will depend on manufacturer (or actuator type) given the the JBD EMA pit dimensions (current actuator stroke is about 18 inches with max raise/lower time 6/8 seconds). |
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| 1/20/23 | Q. | Is the Navy looking to replace the whole EMA or just a part of it. |
| A. | Current market available EMA are very well designed (for e.g motor coils in aerospace EMA can work for 140 million hours ! There is typically dual channels of control signals also so on..) so have you researched as to what component/s is/are failing a lot more than others in the JBD EMA ? |
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| 1/20/23 | Q. | Can the screw move backwards without any brake when you push on the nut ? In the sense is it very high efficiency? |
| A. | The current EMA are back-drivable when the brake is disengaged. Some requires higher back drive forces than expected (low efficiency). |
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| 1/20/23 | Q. | The pictures provided don't show the hydraulic clutch and brake, so where are they located? |
| A. | The clutch and brake system is only on JBD # 3. The picture provided is a CAD model for one panel of JBD#1, 2 & 4. Each JBD has 6 panels. |
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| 1/17/23 | Q. | Is the JBD(3) deployed on the diagonal landing strip? |
| A. | Yes. |
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| 1/17/23 | Q. | Is it the intention of the USN to replace the existing EMA entirely w/ a new solution, or to source an accessory or "add-on" that enables the existing EMA to achieve the desired function? |
| A. | The objective is to enhance the installed system to achieve safer, faster, more consistent and reliable lowering of the JBDs. |
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| 1/17/23 | Q. | Can general details on the motor, driver, and any state feedback be provided? |
| A. | Actuator motor is a 720 VDC (peak) 460 VRMS, permanent magnet with resolver for feedback. Motor direction, velocity and position are controlled by a Variable Frequency drive in a PLC control system |
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| 1/17/23 | Q. | What is the maximum stroke of the EMA? Is this a ball screw, roller screw, or lead screw? |
| A. | Current EMA stroke is about 18-20 inches and is based on roller screw technology. |
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| 1/17/23 | Q. | Does the 2-arm linkage "lock out", and support the entire weight of a panel when the EMA is fully extended? |
| A. | Yes. |
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| 1/17/23 | Q. | Are these EMAs failing during normal carrier operations or during stress tests? |
| A. | The main issue with the current EMAs is reliability during emergency lowering of the JBD panels. The issue has been narrowed down to actuator back drivability problems. Tests conducted so far revealed high back drive forces on multiple actuators. |
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| 1/17/23 | Q. | I am curious to know if the roller-screw is sourced from Exlar (now Curtis-Wright) or Tolomatic if you're able to disclose. |
| A. | The complete actuators are provided by the shipbuilder and Exlar is the OEM. Do NOT know the source of the roller screw. |
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| 1/17/23 | Q. | Did the original specifications call for the clutch to disengage the EMA from the linkage and the mechanical brake (coupled directly to the electric motor?). |
| A. | The JBD3 hydraulic brake is not coupled with the electric motor. JBD3 current solution involve a hydraulic powered clutch and brake system that disengages the EMA actuator from the crank shaft and controls the panel free fall by the brake. |
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| 1/17/23 | Q. | Do you have a force plot of the reverse motion - or force required to backdrive? |
| A. | No. All backdrive related data were provided by the Ship builder from their vendor and cannot be released. |
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| 1/17/23 | Q. | Can you confirm that the mechanism goes 'over center' at 120 degree and will exert a force to extend the EMA? |
| A. | The linkages lock in over center when crank arm angle is at around 120 degrees from deck, as seen in the plot. Note that the crank arm angle is at 50 degrees from deck when the panel is lowered and travel counter clock wise during raise (actuator rod extends during raise). |
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| 1/17/23 | Q. | Hello, both reference documents are unavailable. could you please provide them? |
| A. | Thank you for bringing this to our attention. Topic N231-053 in this BAA will be updated to include links to the reference materials. Until this update is officially published please use the following:
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