RAPID YETI Statement of Work.pdf

United States Air Force

Arctic Spark/Project Arc Engineering Proposal

Logistics Operational Device Cart (LODCart)

7 August 2024

1st Lt Galen Ryan

2d Lt Morgan Savage

Executive Summary

The goal of this proposal is to create a working Logistics Operational Design Cart (LODCart) that meets the minimum requirements set by key stakeholders. A preliminary design was created by a group of college students and has been included as a starting point for discussions. The initial design as well as the modified 3D printed design of the LODCart are detailed in the following pages. As long as the minimum requirements are met within a reasonable timeline and budget, modifications and designs are allowed.

Background

The United States Air Force partnered with the National Security Innovation Network to help improve the off-loading of cargo in agile combat employment (ACE) environments. The program, called Rapid Yeti, enlisted the help of students from Texas A&M to solve this logistics project.

Previously, the Air Force employed the Combat Offload Method B, which uses metal 55-gallon drums underneath of pallets from a C-130. The aircraft inches forward as a truck helps pull the equipment off…all while airmen are sliding barrels under the pallet. The goal of Rapid Yeti is to create a faster and safer method without the support of traditional unloading infrastructure.

Design Requirements

The LODCart must meet the design and strength requirements determined by the Air Force in order to be implemented in operations. For reference, assume a pallet position is for the 463L pallet (88” x 108”). Designers should also note that the device will be used in saltwater and arctic environments.

The minimum viable product should be made to these specifications:

o The device must hold two pallet positions once expanded.

o Each pallet position has a max load of 10,355 lbs.

o It must collapse into a stowable and towable configuration.

o The wheelbase must fit within one pallet position. The frame can extend a few inches outward.

o The height of the larger cart needs to reach 74” to be coplanar with a C-17 ramp. The height of the smaller cart needs to be coplanar with the C-130 ramp (30” – 45”) and raise to be coplanar with the C-17 ramp.

o The height adjustment system must be simple and robust (ideally without hydraulics for minimum maintenance).

o The device must use a rolling guiderail system similar to Air Force cargo handling system.

o It needs a safety stop for rolling pallets.

o People must be able to walk on top to move/adjust pallets.

Additionally, the aspects listed below should be considered but are not required in the final design:

o It can be towable when expanded and under load. It should to move as one piece so the carts must interlock.

o The wheels must support load of cart and two pallets if I can be towed.

o The device should limit high tech equipment because its use in a deployed environment.

o It should be light enough to be moved by a group of airmen if not under load.

o The device can fit 1-2 Wolverines underneath it in a pallet position. (35.5” tall, 67” x

107”) o The material used to build the carts should be able to be modified by an Air Force metals technology shop.

Initial Design

The Texas A&M team created a few ideas before settling on the nested design called the Logistics Operational Device Cart (LODCart). The nested design is pictured below. The final design incorporates flow rails, frame, weight supports, ACME jacks, rail guards, wheels, and a tow bar.

Figure 1: LODCart Isometric View (Expanded and Collapsed)

Flow Rails

The flow rails are 9’ long, rated for 54,000 lbs each, and designed to be easily serviced (pictured below).

Figure 3: Rail (Front View)

Figure 4: Rail (Side View)

Figure 2: Flow Rail (Isometric View)

Frame

The frame is comprised of three parts: I-Beams, C-Channels, and a rectangular bar. The I- Beams are made of A36 steel while the C-Channels and rectangular bar are made of A514 steel. Below is an isometric of the assembly of the frame.

Figure 6: Frame (Side View)

Figure 7: Frame (Front View)

Figure 5: Frame (Isometric View)

Weight Supports

The weight supports are created using four main beams, cross bracing, wheel mounts, and wheel mount bracing. The material of choice is 4” x 4” x 1/4” square tubing which resulted in a reported safety factor of 4.7 (unknown how that number was calculated). Below is the design of the weight supports.

Figure 8: Weight Supports (Isometric View) Figure 9: Weight Supports (Side View)

ACME Jacks

ACME Jacks are used to change the height of the carts depending on the mission requirements. The jacks are inside the weight support legs. The large cart jack has 24” of vertical travel while the small cart jack has 30” of vertical travel. Each jack is rated for 8,000 lbs and is operated via a crank handle. Below is the section and isometric view of the jacks and the crank handle.

Figure 11: ACME Jack (Isometric View) Figure 12: Jacks (Section View)

Figure 10: Crank Handle (Isometric View)

Rail Guards

The rail guards are used to prevent the pallet from rolling off the LODCart. The material listed in the design is 6061-T6 Aluminum. The rails should be removeable for storage. Below are the rail guards for both the large and small frame.

Figure 13: Large Rail Guard

Figure 14: Small Rail Guard

Wheels

The wheels listed for the initial design were 16” diameter casters with pneumatic textured tires that include brakes (pictured below). The have a four-position swivel lock and are rated for 2,000 lbs each.

Figure 15: Caster Wheel

Tow Bar

Finally, the tow bar is an A-Frame design. It is hinged and is compatible with a 2” hitch ball.

Below is the top view of the tow bar as well as the zoomed in view of the hitch.

Figure 16: Tow Bar (Top View) Figure 17: Tow Bar Hitch

Initial Design Critiques

Unfortunately, due to outside factors, the Texas A&M team was unable to provide the final .stl files. The Air Force did receive a Manufacturing Design Report that included drawings that were 1/10th scale of the initial design. Several modifications were made to the scale model to aid in the 3D printing process. The summer Arctic Spark Cell high school intern was able to recreate the scale model drawings into .stl files. 1st Lt Ryan then used these .stl files to begin the redesign and assembly process in SolidWorks.

In the Manufacturing Report, there were no cage codes or part numbers. The exploded view was also confusing, and the assembly instructions were based on the 3D printer design modifications. These modifications included converting the flow rails into solid beams with a raised pattern and the removal of the jacks. A threaded rod replaced the jacks to demonstrate the height adjustments when the model was printed as a prototype. There was also an additional slot in the weight supports that was specifically designed for the PLA print. The Texas A&M team used superglue to attach hex nuts to the slot covers and insert them into the weight support slots. This addition does not need to be in the final design prototype as jacks or another height adjustment system will be used.

Additional modifications include the framing pieces of the final design should be hollow given the chosen material of square tubing. The students also replaced the hitch system of the tow bar with a pintle system. The pintle systems is more compatible with Air Force towing vehicles than the hitch system. Lastly, the PLA design was simplified to have uniform tubing for the weight supports while the final design had steel plates to support the underside of the weight supports. It should also be noted that there were miscellaneous triangle and stop pieces that were not included in 1st Lt Ryan’s final design because they were non-value added.

Conclusion

The design created by the Texas A&M team is a starting point but not required to be followed exactly. The drawings provided by 1st Lt Ryan showcase the modified PLA design.

While some simplifications were made from the final design to the PLA design, the overall design concepts are intact. Questions about the designs should be directed to 1st Lt Ryan and 2d Lt Savage. Funding and leadership questions should be directed to MSgt Charlie Crea. Contact information is listed below.

Contact Information

Galen Ryan, 1st Lt, US Air Force

Engineer – AFWERX Project Arc galen.ryan.1@us.af.mil

Morgan Savage, 2d Lt, US Air Force

Engineer – AFWERX Project Arc morgan.savage.2@us.af.mil mailto:morgan.savage.2@us.af.mil

Cell: (913) 702-6127

Brian “Charlie” Crea, MSgt, US Air Force

Director of Innovation – JBER Arctic Spark arctic.spark@us.af.mil

DSN: (317) 552-8888, (317) 552-2222

Cell: (609) 621-5751

For questions regarding the solicitation please refer to the combo POCs.

mailto:arctic.spark@us.af.mil