Looking at the photos from some of the other vehicles I have been referring to, I am a bit uncomfortable with the tubing sizes that some of them use. My primary reason is because of crash protection.
Jim Musser's chassis is the most attractive to me because it forms some protection around the occupant. The tubing he employed was 2.00 inch square tubing with 0.12 (1/8 inch) wall. I like that, but wondered if there was a readily available square tubing that might be an improvement.
I have settled on 2.00 x 3.00 x 0.084 (14 gage) rectangular tubing. It is about 10% lighter than the 2.00 x 0.12 square tubing, and is about the same stiffness in the 2.00 direction and almost twice the stiffness in the 3.00 direction. Orienting the 3.00 side vertical in the bottom rails and the 3.00 side horizontal in the top rail of the frame should result in a stiffer frame with a minimum weight penalty. A stiffer frame should be better for performance and definitely better for crash protection.
Tuesday, January 17, 2012
Wednesday, January 11, 2012
Design Rationale: 6 - 8 inches ground clearance
The Sport Cycle has about 4 inches of ground clearance. Last summer, I built a Marauder recumbent bicycle as designed by http://www.atomiczombie.com/ It had 4 inches of ground clearance and it dragged when I rode it over the hump where our driveway crosses an irrigation canal. I modified the frame to 7 inches of ground clearance and that seemed to be a good number.
Design Rationale: Aluminum body
I know that fiberglass seems to be the ideal material for building a custom, one-off body. The problem is that;
1) Any time I work with fluids I make a huge mess and am rarely happy with the results.
2) I have been sensitized to chemicals in the past and don't want to repeat that experience.
3) The resulting aluminum body should be lighter than a fiberglass version would be.
4) Working with aluminum sheet metal looks like a ton of fun and a natural extension of my current skill set. I also think that once I am tooled up and have some experience with aluminum sheet metal that I will be faster working with it than with fiberglass.
1) Any time I work with fluids I make a huge mess and am rarely happy with the results.
2) I have been sensitized to chemicals in the past and don't want to repeat that experience.
3) The resulting aluminum body should be lighter than a fiberglass version would be.
4) Working with aluminum sheet metal looks like a ton of fun and a natural extension of my current skill set. I also think that once I am tooled up and have some experience with aluminum sheet metal that I will be faster working with it than with fiberglass.
Design Rationale: Non-tilting design
There are a number of 3 wheel vehicles that have been or are in the process of development that utilize tilting, like you see in a motorcycle going around a corner. There are huge benefits in handling with this approach and it has been a real temptation to incorporate this feature into the design.
However, there are some very big challenges to a tilter that I won't elaborate on here. Because of the scope of the project without the added complexity of a tilting design I have elected to stay with a conventional steering system. This project is on my "Bucket List" and I need to keep it reasonable if I am going to get it done.
However, there are some very big challenges to a tilter that I won't elaborate on here. Because of the scope of the project without the added complexity of a tilting design I have elected to stay with a conventional steering system. This project is on my "Bucket List" and I need to keep it reasonable if I am going to get it done.
Design Rationale: 500cc Ninja powertrain
A variety of engines have been used for vehicles similar to what I am working on. The XR3 and the MAX both use small Kubota diesels. The Indy Cycle built by Jamieson DuRette uses a 750cc motorcycle. The Sport Cycle by Jim Musser was designed around an 1100cc Kawasaki. One of the Sport Cycle kits that Jim produces was powered by a 600cc bike. The HyperRocket is powered by a 250cc Ninja.
Fuel mileage for the XR3 and MAX is in the 50 to 80 MPG range. The Sport Cycle with the 1100cc engine gets about 45 MPG. The HyperRocket gets 100 - 125 MPG.
Initially I settled on a 250cc Ninja, largely based on the performance of the HyperRocket. However, the HyperRocket was developed in Michigan and I live in Montana. My commute includes some moderate hill climbs and I believe the frame on my vehicle will be heavier than that of the HyperRocket. In a conversation with Jim Musser, he shared that the Sport Cycle that featured a 600cc power plant still had excellent performance, I decided to look for about a 400cc bike.
Knowing that I might have to gear the bike down using a larger rear sprocket, a 6 speed transmission and the capability of high RPM would be important in order to meet quick performance and sufficient power required for good handling in traffic and hill climbs.
I found a 1989 EX500 Ninja on Craigslist for $300 - in boxes - but the price is right. The odometer shows 6800 miles, so I snapped it up.
Fuel mileage for the XR3 and MAX is in the 50 to 80 MPG range. The Sport Cycle with the 1100cc engine gets about 45 MPG. The HyperRocket gets 100 - 125 MPG.
Initially I settled on a 250cc Ninja, largely based on the performance of the HyperRocket. However, the HyperRocket was developed in Michigan and I live in Montana. My commute includes some moderate hill climbs and I believe the frame on my vehicle will be heavier than that of the HyperRocket. In a conversation with Jim Musser, he shared that the Sport Cycle that featured a 600cc power plant still had excellent performance, I decided to look for about a 400cc bike.
Knowing that I might have to gear the bike down using a larger rear sprocket, a 6 speed transmission and the capability of high RPM would be important in order to meet quick performance and sufficient power required for good handling in traffic and hill climbs.
I found a 1989 EX500 Ninja on Craigslist for $300 - in boxes - but the price is right. The odometer shows 6800 miles, so I snapped it up.
Tuesday, January 10, 2012
Design Rationale: 1000+ mile range on a tank of fuel
Life for our family tends to be paycheck to paycheck - maybe you can relate. With this range, I can fill the tank on payday and it should be sufficient to make it to the next payday. 'Nuff said.
Design Rationale: Enclosed cabin
Many of the three wheeled vehicles out there or in development have open air cabins. I plan to use this vehicle as a daily commuter when we don't have snow on the ground, so an enclosed cabin is a must. This does present a more difficult project with particular challenges regarding sourcing glass. My garage is also typically used for projects, not parking, so I don't want this thing becoming a stagnant "car pool" in the winter time.
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