Entry Title: MLV-Universal Basic Vehicle Team Leader: Brennan Metcalf Team:

Transcription

1 Entry Title: MLV-Universal Basic Vehicle Team Leader: Brennan Metcalf Team: Summary of Proposed Solution The included concept is a Universal Basic Vehicle that is designed only to provide a dependable and capable starting point for future mission needs. Rather than solve all the problems at once, we only need to give soldiers the proper size, and quality, canvas to work from. This design pulls heavily from lessons learned in past conflicts, back to WWII, while applying modern manufacturing process and mass produced components to lower cost. Detailed Description + Supporting Drawings/Sketches/Visuals -The chassis is to be a mild steel tube weldment assembly that is processed on a cnc tube laser. Many of the parts repeat in the chassis. The tubes are to be a common size to facilitate field repairs or modifications. Tube wall thickness can be adjusted, or supplemented, to help meet weight goals vs durability requirements. This type of structure is typically very strong for its mass as it spreads the load out over multiple tubes. This feature also gives redundant strength in the chassis in case of damage to a specific area. -The flat sides and tube profiles on the exterior of the vehicle will facilitate the ability to add some ballistic or weather protection panels if required, or be stripped down to the bare minimum

2 to increase payload. Mounting locations are to be provided directly on the tubes that form the chassis similar in concept to how accessories can be mounted on a modern rifle forearm with a MIL-STD-1913 rail system. Tie down points, or any other modifications, can be attached to the common bolt pattern using hand tools. -The overall size maxes out the available volume requirement for the project. This allows the vehicle to carry as much bulk as possible without having to load/unload the vehicle during transportation. The vehicle can hit the ground running ready to deliver payload ricky-tick. The tires are at the corners of the vehicle to allow a beneficial approach and departure angle for cross country travel. The belly of the vehicle is to be flat and smooth with a protective skid plate,to prevent vehicle damage from a high centering situation, and allow it to be lifted using any conventional fork lift with standard tines. The vehicles can also be stacked onto each other to provide more effective use of storage volume in certain situations, or to facilitate the recovery of damaged units when required. -Generally this is designed to be a conventional 2-seater in its most basic form, similar to what you would think of as a Jeep or modern UTV. The rear cargo area can provide seating for an additional 2-4 persons. In an emergency situation, soldiers and/or civilians, could be piled on any surface of the vehicle. With the space frame construction it would only be limited by your imagination and the ultimate failure of the axles/suspension. The main occupants would be contained in a ROPS ( Roll Over Protection System ) structure to keep them safe at higher rates of speed over uneven terrain. That structure could be modified for additional requirements as needed with additional triangulation or up-sizing of the main supports ( vs the curb weight restriction ) -Powertrain. The UBV is to be powered by a modern small ~2L displacement aluminum turbo diesel engine that can be run on JP-8 fuel to meet military standard requirements. It is to be configured into a field-replaceable power-pack system with a FWD style transaxle sourced from the automotive industry. My recommendation would be for a GM MDE 1.6L turbo diesel engine ( ~150hp/250ft/lbs) mated to the GM 9T50 9-spd transaxle with a ~2.9 final drive ratio. The engine would be mounted longitudinally in the chassis, but completely behind the front axle to centralize the weight. The outputs from this trans-axle would feed the front and rear axles similar to how a conventional transfer case works. It would be beneficial to develop a selectable locking differential for the final drive in the trans-axle to give true 4wd performance off-road. It would be designed so that the engine/transmission power-pack system could be dropped out the bottom of the vehicle by using the cage structure of the vehicle as a hoist system. The cooling system may need to be located external to the power-pack due to space restrictions. This system should provide a normal vehicle speed range of 0-45mph with the ability to run near 60mph in emergency conditions. These ranges may be adjusted for specific mission needs by swapping either the axle, or final drive, gearing. -Drivetrain. The axles on this vehicle are intended to be of a beam type with a drop out center section. They are to be designed so that the front and rear axle may share as many parts as possible. It would be preferable if items like wheel bearings could be serviced instead of only

3 replaced. The rear axle could be upgraded to provide 4-wheel steering if required. With some additional planning the entire axle assemblies may be able to swap front to rear in the vehicle. The steering components on the rear axle could be locked out if not needed by providing an additional short tie rod link and bracket. The drop out center section should contain a ring gear of ~8-9" in diameter. Using something common from the existing automotive field should provide the additional benefit of providing traction aiding differential options. It would be beneficial if the front and rear driveshaft could be designed to be the same basic length for parts commonality. -Suspension. The front and rear suspension are to be as identical as practical to share components and keep part count low. I would suggest a 5-link system where the upper and lower control arms are all the exact same length. The panhard bar could also be common front to rear and/or common in length with a steering link. Because the load carrying capacity of the vehicle is so broad, this needs to be addressed in the suspension. Option 1: 4 corner air bag suspension that could be adjusted on the fly. Option 2: Coilover suspension where the springs could be changed with the vehicle weight if needed. Option 3: pick a spring for the max weight and deal with the decrease in ride quality in the unloaded condition. The spring and shock system is to be the same at all 4 corners to share parts. -Steering. For safety, the steering system should be mechanical in nature if possible. This would include a steering box mounted on the frame rail with a power steering pump on the engine. There are other options that may warrant some investigation such as full hydraulic or electric assist systems. The rear axle could also be of a steering design if required. This will come with a weight penalty and/or an increase in required operator skill. The main frame rails are to be as narrow as practical to maximize steering angle. -Tires/Wheels. The wheels are to be a common size. In the current off-road market this would be a 17" diameter with a width of about 8-9". The lug bolt pattern should also be common. The backspacing should be as high as practical, with the widest axle possible, to decrease scrub radius, decrease steering force, and increase axle overall width. The wheels could be designed with a 2pc system to facilitate field repairs of the tire. The 2pc design could also provide the opportunity for the addition of a bead-lock and/or run-flat system. The tire is to be a 35-37" diameter with a section width. Current production tires in this size would provide a load range D-E rating to allow an increase in emergency payload capacity and tire durability. Tread pattern is to be determined by intended use. Tire width could be increased beyond the width specification for special use in boggy, sandy, or snowy conditions. It would be beneficial to provide a CTIS ( Central Tire Inflation System ) to adjust tire pressure on the fly for specific conditions. The CTIS will complicate the wheel end assembly on the axle and come with a weight assembly. A spare tire/wheel could be included if required at a weight and cargo volume penalty....provide a good basic design and let people s imagination run wild.

4 Concept Layout in the specified development envelope Preliminary Chassis Scale Layout.

5 This is the basic concept for the modular attachment system I am proposing. These holes would be cut when the chassis tubes manufactured on a cnc controlled tube laser cutting machine. The clip nuts are an off the shelf industry part. This idea could be applied to any flat tube surface in the chassis. It would also lighten the chassis significantly without a large negative effect on the strength of the weldment. This system would also be used to mount the belly pan, interior panels, switch panels, controls, seats, etc. The downside is that the chassis could collect debris on the inside of the tube. It could be washed out easily. The holes could also be sealed fairly easy with light plastic plugs or something similar.

6 CONSTRUCTION SUPPORT PERSONEL TRANSPORTATION

7 Inspiration I draw most from past vehicles that where requested by the military to fill similar roles. This includes a lot of personal experience I gained from the rebuild of my 1942 Willys MB. Here we are still trying to improve on this basic vehicle concept that was designed over 75 years go. A simple 4wd vehicle that provided a blank canvas for decade s worth of improvements. What have we learned about how to do these things better. Feedback Questions/Answers raised from the preliminary posting. The basic, no-frills design is great. We had it with the jeep as an all-purpose vehicle around base. It was lost with the HMMWV, a vehicle that was too big and cumbersome to be an utility vehicle. U.S. military then resorted to acquiring civilian vehicles for this purpose, e.g. Toyota Hilux in Iraq/Afghanistan and Chevy/Ford in the U.S., but it takes time, resources, and skill to acquire and maintain such vehicles. A modular vehicle that Marines train, use, and can take to the field means an added level of flexibility at small combat outposts. A few thoughts: 1. Hood cargo area. I think it is useful, and it will be employed. However, it will be difficult to convince commanders to permit Marines to lash cargo on it, especially in the rear where there are a lot of watchful eyes, with the issue of visibility, and you have a good chance that its utility may be completely nixed after that first accident. Is there anyway you can employ this space?

8 2. Modular & Additive Manufacturing. What are ways that you can take advantage of additive manufacturing? One aspect I thought was using a 3D printed unibody design that the Marines can print using the modular 3D factory and assemble the vehicle using stock parts, e.g. suspension, engine, transmission. 3. Center of Gravity. One issue with the ITV or Growler that I have heard a lot about from my fellow Marines is the tendency to roll. Is there anyway to address this issue given the requirements, i.e. small dimensions, need for ground clearance, and ability to traverse rough terrain. Collapsible / Expandable. Is it possible to remove the roof for transport? What are your thoughts on a trailer system or cab? Detail Reply to the above. 1. The hood space could be used in a variety of ways. The user would have to be responsible about the safety aspect of things. It could be de-evolved into just a simple flat sheet of material if that keeps the powers at be handy. When the situation demands it, the space could again be used. A flat surface that big is going to be useful at some point...it wasn't uncommon to see a old military Jeep with a stretcher over the hood in historical pictures. Heck, it would make a good table for chow or a place to lay out a map also. The hood could also be used mainly for low profile items that wouldn't effect visibility. You could mount a recovery rope, pioneer tools, etc. That would occupy the space to discourage other use, but not completely eliminate the overall utility if you needed to thow an injured solider on there for emergency evac. 2. The entire vehicle was designed to be as modular as possible, not only in a modern setting with something like 3d additive manufacturing, but also in the field with what you can find or reappropriate. The body panels are generally all designed to be essentially flat. In my proposal I outlined cutting a specific pattern into the flat surfaces of the chassis tubes. That pattern allows a simple 'clip-nut' to be used on a simple repeating pattern. Basically every 1.5" or ~40mm you would could have a 1/4-20 or 6mm mounting bolt. This gives you a modular repairable ( if you where to strip a clip nut) attachment point for a common fastener anywhere along the flat surfaces of the tube. This would mean that you could bolt anything onto the main chassis. It wouldn't matter if it was a flat sheet of aluminum scavenged from a street sign, or a 3d printed part. I would also propose that parts commonality of the powertrain, drivetrain, and suspension be carefully studied to limit part count. It would be valuable if you only needed to have one spare control arm to cover any location on the vehicle. The steering tie rod, drag link, and panhard bar all used the same length of tubing with the same threaded ends. The same shock would work at any corner. All that will have value when you are trying to repair these in the ditch or break damaged units down for spare parts. 3. I would be very important to build the vehicle as low as practical. With the way this vehicle is designed, the overall height could be adjusted fairly easily. Getting most of the heavy parts as low as practical would be very important. The powertrain 'power-pack' and seats would basically be mounted to the belly pan of the vehicle. It would be valuable to test the vehicle to determine the proper balance of ride height vs stability vs off-road performance. My personal 1942 Willys

9 MB project is very similar in size to something like this. I went to great lengths to keep the center of mass compact top to bottom, but also provide the most ground clearance possible. It will do things with a much shorter wheelbase that makes most other vehicles blush off-road. It is also similar in width and tire size to what I am proposing. Generally, I would mount everything as low in the chassis as practical...engine, transmission, battery, fuel tank, seats, etc. Also, limiting the weight of all these components would be advantageous. Beyond that, we could look at active solutions. One of the suspension systems I proposed was based on commercial air bags. With that suspension you could adjust the overall height to help with lateral stability for higher speed or off-camber off-road use. We could also look at the addition of a torsion bar based sway control system. In the end, rolling over is typically a dynamic problem. It is typically pretty difficult to overturn a vehicle in a static situation. Driver training and experience will help them get a 'feel' for when things are getting close. 4. I could design the roof section to be removable or even collapse down if required. As the vehicle is used and sustains some damage having large major sections be removable could cause issues with assembly however. The chances that the chassis could get a little 'sprung' and the parts not line up goes up with service use. For transportation there are other things we could do to maximize weight vs volume. If it had an air suspension we could let that down completely to save vertical space. The tire pressure could be lowered for transport also. With the proper cage strength you could even stack two of these on top of each other fairly easily if you had a forklift or a ramp system. There is no reason it couldn't tow a trailer, or another unit. You could even stick a non-running units front tires on the rear deck of a running unit and lash them down to allow towing the damaged unit. With the addition of some simple rubber bumper sections you could push another also. An enclosed cabin would also be an easy addition with the modular mounting system I propose. You could fabricate the majority of it out of flat sheets of clear plastic like Lexan. Add in a few 3d printed hinges and latches. I believe in the proper thickness that could even provide some ballistic/blast protection. I believe the KEY to all this is to provide the proper blank canvas. We shouldn't be trying to solve every possible configuration now risking being too specific (but it is sure fun to think about them!). To meet the curb weight requirement I believe we need to concentrate on the stripped down basic version. Team Brennan Metcalf Engineer Ex-Wildland Firefighter, 6 years BLM type 6/4 engine boss, 4 years Helicopter Rappel ICT4 Avid off-road enthusiast who builds his own vehicles from the ground up in his garage.

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