Robert Q. Riley Enterprises: Product Design & Development
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XR3 Hybrid FAQ's
Frequently Asked Questions

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Questions & Answers

Do I need plans if I buy a kit, and when will kits be available?

   Frame and body kits will be released prior to the release of turnkey vehicles.  A release date has not been established.  When we have complete information, it'll be announced on the XR3 page at this site. Kits and completed vehicles, however, will be purchased from XR3 Motors LLC.  A link to their site will be placed on the XR3 information page.  You will need the plans in order to build the XR3 from a kit.

Plans purchasers will receive a special discount on kits and  completed vehicles.  You will be notified by email when kits and completed vehicles are scheduled for release.

Will you continue development after plans are released? A   Yes. The XR3 is slated for an extensive development program.  Testing and optimization will be done by one of the nation�s top automotive research centers.

Will plans buyers be informed of improvements?
A   Yes. Improvements will be integrated into the design and passed on to purchasers via a special website. Details are in the construction manual that comes with the plans.

When I purchase a Standard Plans Package, will I still get all of the drawings?
A   Yes. You do not have to purchase the Deluxe Plans Package in order to get a complete set of drawings and instructions. The printed plans (Standard Plans Package) are very detailed and complete. The Deluxe Plans Package comes with everything in the Standard Plans Package, but the electronic files give it far greater functionality � functionality that�s impossible to provide on a printed page. You also get video of the construction on DVD. The Deluxe Plans Package puts the XR3 Hybrid construction plans far above anything that�s available from anyone else in the DIY field.
Do I need a CAD system to build the XR3? How can I use the electronic files on CD-ROM if I do not have a CAD system? A  You do not need a CAD system to see the 3D models or to build the XR-3 Hybrid.

You can view the 3D eDrawings models, for example, by using an eDrawings viewer that you can download for free on the internet. The viewer lets you take dimensions, do cutaways, isolate single parts in an assembly, and zoom, pan, and rotate the model so you can see every detail. If you�d like to try it, you can download an executable eDrawings file of the Front Wheel and Knuckle Assembly model (3.23 MB) by clicking on the foregoing link. You have the option to either Run or Save the file.

Try all the features and see how it works. The eDrawings viewer has great functionality, but you cannot make changes to the model. The viewer will also let you view native SolidWorks models. But changes can only be made if you have a SolidWorks CAD program.

The 3D CAD models are just one of the many benefits of the Deluxe Plans Package. The CD-ROM offers a lot of additional benefits, including a computer version of the construction manual (that runs in your web browser), 2D CAD files in several formats, and DXF files that can be used to inexpensively water-jet cut many parts. There are many more features too.
Q  Will there be a chance to test drive the XR3?
A  Test drives are not available at this time. It's on the agenda to build 6 to 10 pre-production prototypes.  Once we have a few vehicles, then we�ll set up a system for test drives. Most likely, that will first become available in the Cleveland area at the XR3 Motors facility.
Q  Are you planning to manufacture the carbon fiber body �in house� or are you planning to subcontract it out? A  We will not make the body in-house. As for carbon fiber itself, we�ve decided against using it. A worldwide shortage of carbon fiber exists due to military and commercial aircraft usage. So the price is prohibitively high and it�s not reliably available.

Carbon fiber also has some negative characteristics that tipped the scale against it. For example, on failure it can break into knife-like pieces that can be dangerous in a collision. And the actual weight savings over the foam/fiberglass composite we�re using amounted to only about 75 pounds or so. So we reconsidered the idea of using carbon fiber.

We picked up the necessary strength by relying on a composite sandwich construction with which we�ve had lots of experience and great success. The hollow sides below the canopy separation lines are filled with foam for extra strength and side impact protection. And there�s a foam-filled region around the perimeter of the rear cabin bulkhead that creates a built-in roll bar. Foam-filled regions like those are more than 50 times stronger per given weight than conventional single-skin fiberglass.

The construction manual, however, includes tips on how to work with carbon fiber for those who want use it.
Q  What are the options for the body? I can handle the mechanical aspect, but not the foam build-up. When will kits become available? A  The options are to build it according to plans or buy a body kit when they become available. Plans show how to build the one-off body just as we did with the prototype. It�s a surprisingly easy-to-learn and forgiving system, and the instructions are oriented to the inexperienced novice. For an overview of how it�s done, see the document at:  A body kit will become available just as soon as we can make it happen.
Can I build the XR3 as a pure electric- or pure diesel-powered vehicle? A  Yes. The XR3 chassis is a highly-customizable modular design. It�s designed to provide the builder with nearly unlimited choices on how to set it up. And you can upgrade at any time simply by changing out the front or rear sub-assembly.

For a battery-electric vehicle you�d simply leave off the entire diesel power train. There are two ways to do it. You can leave the front wheels free-wheeling and use the rear wheel drive setup shown in the plans. Or you can leave the VW transaxle in place and use an aftermarket adapter to attach the electric motor to the VW transmission. (We can provide drawings for an adapter, but they are available readymade.) In this case, the rear power train would be left off and the rear wheel would become free-wheeling. The rear wheel drive setup is more efficient than attaching the motor to the transaxle to create a front wheel drive arrangement. And the rear wheel drive leaves more room up front for batteries.

For a high-mileage diesel vehicle, simply leave off the electric power train and batteries and let the rear wheel become free-wheeling. You can expect to get about 125 mpg with this setup. In either case, follow the guidelines in the manual so the center of gravity ends up in the correct location.
I�m interested more in high-performance than I am in high fuel economy. Can the XR3 be built as a performance car? Yes. Again, this is due to its modular design. The VW Type One transmission can handle up to 300 hp. (Do not read the forgoing as a recommendation of 300hp.) If you install a significantly larger engine, the front clip will probably have to be lengthened to accommodate the increased size of it. The front clip is a removable section of the body that begins at the base of the windshield. When kits become available, we plan to offer different front clips for bigger engines.
Q  Do you have any plans that cover turning this vehicle into a hybrid gas and electric? Plans provide lots of information on hybrid power systems. And substituting different engines is easy. But you may be asking about a series hybrid, which uses an engine that powers a generator so the motive power is totally electric. This type of hybrid is called a �series hybrid.� The XR3 is a �parallel hybrid.� There�s a discussion in the manual about the various types of hybrids and why we are using a parallel hybrid system. But if you are asking whether it�s possible to convert to a series system, the answer is yes. There�s plenty of information in the construction manual, but we do not provide detailed plans for a series hybrid system.
Q Will this vehicle have tilt with turning or is it a standard suspension? A  The original concept for the XR3 included a tilting suspension system. But we decided against it for a variety of technical reasons. So the XR-3 has a conventional suspension system.
Can you give me an estimate of battery cost? A  We paid $7,500 ($8,900, including freight from China and a battery management module) for the Li-Ion batteries used in the prototype. Since that time, other lithium-based batteries have become available.  So stay in touch with the XR3 Group on Yahoo for the latest information (see the link in the left margin on the XR3 information page).  As an alternative, a lead-acid battery pack, consisting of eight Optima D34 batteries, for example, will cost on the order of $1,500.
What about the total cost to build it? Does the price I saw mentioned in the article - $18,000 - refer to a plans-built vehicle or a kit? A  We had not calculated a cost to build when that article was done. The figure mentioned in the interview was a rough estimation for the plans-built car. If you�re thinking in terms of Li-Ion batteries, that figure is low. For a vehicle having lead-acid batteries it�s in the ballpark.
Does it meet California's CARB requirements? It will meet California Air Resources Board (CARB) standards for homebuilt motorcycles. Three-wheelers (of under 1500 pounds) are classified as motorcycles in California. If it does not meet local emissions standards, you are entitled to a one-time-only exemption from motorcycle emissions standards for a homebuilt or customized motorcycle. If your state classifies the XR3 Hybrid as a passenger car, then you can install a catalytic converter and particulate trap. Since ultra-low sulfur diesel fuel was introduced at the end of 2006 (in the U.S.), catalytic converters will work on diesel engines.
Q  Will plans give enough detailed information so someone with no experience can build it?
You�ll be very impressed with the amount of detail in the plans. Plans are written with the assumption that the builder has no prior experience with this level of fabrication. And the quality of the presentation is outstanding - not just lots of information, but professionally presented as well.
Q  Can you drive it on public roads?
A  Yes. See the document at:
Is there a minimum temperature limit? A  Batteries are sensitive to cold. And Li-Ion batteries have different cold-weather limitations than lead-acid batteries, either of which can be used. The temperature limitation of the batteries will be the only temperature limitation on the vehicle. Valence Lithium-Ion batteries are rated for an operating temperature of -10�C to 50�C (14�F to 122�F). Lead-acid batteries are more cold-sensitive, with only about half their rated output at -15�C (5�F).
Are there special concerns regarding operation on snow/ice covered roads that are different from other vehicles? A  A three-wheeler will give you feedback just like a four-wheeler. Normally, it�s easy to tell when you are pushing the vehicle beyond it limits. Over-powering the rear wheel in a turn on ice, snow, or wet pavement can cause breakaway. The same is true of a RWD four-wheel car, but the single rear wheel may breakaway sooner. A good option for slippery surfaces would be to switch to the diesel only mode, which delivers power to the two front wheels and leaves the rear wheel to simply follow along. You�ll end up with road-holding power similar to that of a conventional FWD car.
I�m 6�4 and 280 lbs, my spouse is shorter but about 180lbs. Comfortable seating would be important. Would this be suitable for us?
A  You will probably have to raise the roofline. The headroom is based on someone of 6�0. You can assume that half your height is in the seat-to-roofline direction and a little less than half (because of the bend in the legs) is in the tailbone-to-firewall direction.
I am 70 years old and not as agile as I once was. Would getting in and out of this vehicle be a problem? The step-over height is 20 inches. So you can try it at home and see how it feels. Keep in mind that the floor of the cabin is about six inches above the ground, and you can hold onto the canopy as you�re stepping over the side. So you�d want to try it by stepping onto an elevated floor, and do it next to a stable structure that offers a grab-point like the canopy.
Q  What vehicle is used as the donor? Keep in mind that you have an international audience and not everyone has access to �unique� American vehicle parts?
The XR-3 uses a specially built chassis, rather than one from an existing car. But aside from the structure itself, it�s assembled from stock automotive and industrial parts. FWD knuckles, hubs, and brakes are from a Chevy Cavalier, but others will work just as well. The construction manual provides guidelines on what to look for when substituting different parts. The rack & pinion steering comes from Maval Gear, an American supplier of hot rod components. There�s a dedicated model number for the XR3 rack & pinion, and Maval will ship internationally. The air springs are an off-the-shelf part made by Firestone. They are widely used in air-ride conversion kits. Ball joints, bearings, and cog-belt drive components are widely available industrial or automotive components.
Q  What is the total length and width of the widest part of the XR3?
A  128-� X 74-� inches
Is there any information available as to type of powerplant � electric, batteries, and engine?
A  The engine is a Kubota D902 tractor or industrial engine. The electric motor is an Advanced DC Motors Inc. 8-inch motor. Batteries in the prototype are Li-Ion but the XR-3 will also accept lead-acid or nickel-metal hybrid batteries.
What�s the displacement of the diesel you're using? A  The displacement of the engine is 0.898 liters or 54.8 CID. (A news reporter in one of the film clips linked to the XR-3 information page incorrectly states that it is a 3 liter engine.)
What surprises me is that you have not chosen a more exotic engine that is more energy efficient, less polluting, has a multi-fuel capacity, and a lesser weight to horsepower ratio than today�s conventional engines. I am thinking about the �Bourke� engine. What is your perspective?
A  The chassis can accept other engines. And you can also run alternative fuels. We selected the Kubota diesel because it is readily available, reliable, highly efficient, relatively inexpensive, and it comes in gasoline and natural gas versions. Also, it�s a very clean-running engine just as it comes. And since the introduction of ultra-low sulfur diesel fuel in the U.S., you can now install a catalytic converter on a diesel engine. In fact, there are companies that will custom-make a catalytic converter for your particular engine (they're expensive). And bio-diesel fuel, even the low-bio blends, will further reduce emissions. But the bottom-line answer is that you are free to install a different engine.
I like the concept but I do not like the canopy. Is there a way to access the passenger area so that the inside does not get wet when it is raining? If you are building the body yourself, you have the option of putting in different doors. But getting wet in rain is not a big issue unless you�re in a downpour. The returns around the canopy engagement area of the body are designed to channel water to the outside when the canopy opens.

Benefits of the canopy include ease of ingress and egress due to the wide-open passenger zone and better side-intrusion protection because the body remains integral up to the canopy separation line. Also, the canopy can fully open in tight parking spaces. And it�s easy to convert the vehicle to a roadster or convertible by installing a different top. The canopy of the XR-3 can be removed in minutes by removing the hinge-pins at the front and the air cylinders (hatchback lifts) at the sides.

But the canopy-style opening is very unconventional and it has shortfalls like the one you mentioned. Other shortfalls include the fact that passenger and driver doors have to be opened at the same time and the weight of the canopy has to be counterbalanced by air cylinders (or other means). A canopy also tends to limit retraction space for side windows. But the wide-open access and the ability to create a dramatic, molded-to-the-occupant look to the interior are unbeatable attributes.
Q  Can you tell me what vehicle you intend to get the windscreen and side windows from, or are they going to be supplied from you? Windows for the plans-built car are made of polycarbonate sheet. This is legal for the motorcycle classification, but not for the passenger car classification. Plans also will include instructions on cutting down a curved windshield from a minivan, as well as a vendor who will do it.  Wipers and a safety plate windshield will be required to meet passenger car regulations. (See the subsequent question about wipers.)
Q  Since not everyone that would like to build this beautiful auto lives in Arizona, or some other state that barely gets rain, I am hoping that you either add windshield wipers, or at least give the option on a separate sheet, or in the building instruction book. � Are you?
A  There are no wipers on the prototype. But installing wipers is a simple matter. The entire windshield can be wiped with a single wiper blade. You can use the wiper assembly from a hatchback car. Plans show where to locate the pivot point. The motor and linkage will have to be installed on the canopy so everything follows the canopy when it�s opened. You�ll need a long blade, like the type used on busses and trucks. And you�ll have to install a glass windshield (see previous question). Wipers will scratch an acrylic windshield.

You can install a flat safety plate windshield by flattening out the engagement flange around the windshield. In other words, leave the body curved, but make the windshield engagement area flat and install flat laminated safety plate. Or a curved safety plate windshield, from a minivan for example, can be cut down to fit.  If you go this route, purchase the windshield in advance so you can match the curvature around the windshield region of the canopy to the curvature of the safety plate windshield. And when you purchase the windshield, make sure it is roughly the same height as the XR3 window area.

Later on, a glass windshield and wiper assembly will be available as separate components after kits have been released.

What about side view and rear view mirrors?
A  You can install conventional side mirrors. But we like the idea of rearward-looking video with LCD panels mounted on the instrument panel to provide a panoramic view behind the vehicle.  To meet vehicle code, however, you will have to install side mirrors even with a rearward-looking video system. 
What about headlights and tail lights? A  Plans provide sources for the parts and instructions on how to do it. Headlights are projector lamps with �angle eye� illumination. The tinted covers are made from 1/8 inch acrylic sheet. When you cut out the sections of the fenders for the headlight bays, save the pieces that are cut from the fenders. Cut 1/8-inch acrylic covers slightly oversize, heat the flat sheets in an ordinary oven, then press them into place over the pieces that were cut from the fenders. When the acrylic cools, you�ll have perfectly formed covers for your specially-made headlight bays.
Q   What about front and rear bumpers?
The front is foam-filled and the rear tire serves as a rear bumper. A frontal impact will likely damage the removable front clip. The rear wheel is capable of absorbing a much greater impact without damage.
Q  Will the side windows retract?
A  Side windows are removable, but they can also be hinged so they open outward at the rear. Originally they were intended to retract into the canopy sides. As it turned out, however, the available space limits retraction to about 8 inches.  But retractable side-windows are a viable option.
Does it have an adjustable seat?
A  The seat is not adjustable. The control pedals are adjustable.  Adjust only the pedal pads, not the entire pedal assembly.
What about right-hand drive?
A  The design makes it easy to put the steering and foot pedals on either side.
Q  Do the plans include an interior roll bar?
A  A composite structural element at the rear of the cabin serves as a roll bar, similar to the one built into Tri-Magnum. There�s room for a metal roll bar if desired. But the composite structural element is very strong. The canopy has a steel cage, along with steel A-pillars, laminated into the inside of it.
There is no mention of air conditioning or heating. How is that handled?
A  The prototype will not be equipped with a heater or air conditioning. Since the engine is water cooled, a conventional car heater can be easily installed. An aftermarket AC system can also be installed. One should consider, however, that an AC system will demand five horsepower or more. So you may want to increase the size of the engine and settle for less fuel economy.  These issues are addressed in the construction manual.
Does it have compartments inside the vehicle? A  Not inside the cabin of the prototype. But there is room for storage areas. And the rear can be built with a storage compartment too. Just keep the weight of loads light and low, and as close as possible to the rear cabin bulkhead.
Q   Will Rhino work to manipulate the Solidworks files? No. You�ll have to use Solidworks. Rhino is a NURBS modeler and Solidworks is parametric modeler. You can import SolidWorks models into Rhino, but you will not be able to manipulate them as you would in SolidWorks.

Q  Can you explain the difference in fuel economy between diesel and hybrid driving modes?

A  That�s a good question. When you can drive on two fundamentally different power systems � one that uses petroleum motor fuel and one that does not � establishing overall �fuel economy� becomes a slippery issue.

The hybrid mode does not directly enhance fuel economy.  It does it indirectly. The actual fuel economy figure depends on the details of the particular trip - how much you rely on battery power and how much you rely on diesel power. 

The XR3 gets 125-mpg in the diesel-only mode.  In the battery-only mode "mpg" is no longer a meaningful benchmark because the vehicle consumes no motor fuel at all.  That�s the real benefit of a plug-in hybrid.  It lets you drive on battery power alone for those trips that are within the range of the batteries.  And if batteries become depleted you can switch to the diesel mode and continue driving.  If you traveled 40 miles on battery power and then switched to diesel power for another 40 miles, trip-average fuel economy would be 250-mpg.  The Chevy Volt, GM�s plug-in hybrid concept car, originally advertised 150-mpg by assuming a 60-mile trip with 40 miles on batteries and 20 miles on power from the on-board ICE-powered generator. If you used the same assumptions to determine the fuel economy of the XR3, you�d end up with 375 mpg

In order to arrive at a cost-per-mile for the energy consumed, you�d have to factor in the cost of electricity. But the effect on total petroleum consumption is real.  Only about 5 percent of U.S. electrical power comes from oil.  In addition, electrical power costs significantly less than motor fuel. Plus, petroleum motor fuel has external costs (transfer of wealth, military, health, and environmental costs) that more than double the at-the-pump price that motorists pay for it.  

Q  Are your plans available in SI or metric units?
A  No. They are all in American units. This is a tough issue. Over 80 percent of our sales are to U.S. residents, and the U.S. has been slow to convert to SI units - at least on a consumer level. In the U.S., common sizes for steel tubing and other ordinary building materials are still mostly in inches and feet, but it is slowly changing. In the meantime, we design to common material sizes and use the units that the majority of our customers are familiar with. And it doesn�t work to simply switch dimensions to SI units after something has been designed. Specs for bearings, fasteners and other components do not match up well, and dimensions end up looking nonsensical. A 48-inch-long board, for example, looks right in American units (exactly four feet long). But a 1219.2 mm board doesn't make much sense to folks who work in SI units. When dimensions are simply converted after the product has been designed (which can be done automatically in CAD), common dimensions and sizes end up looking a little crazy.


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