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Building a NASA NP01 Prototype the Right Way with StopTech! Part 2

by Mike Kojima

Ever since we laid eyes on the conceptual drawings and parts of the NASA/Elan NP01 at the PRI Show 2 years ago, we have been enamored by it.  Since we have loved the exotic cars in the various Prototype classes throughout history, we saw the NP01 as the affordable Prototype anyone could own. The fact that it looks like a contemporary P class car seals the deal!

The NP01 can be bought as a complete running car or as a kit.  In kit form, it is assumed that the people assembling it have a pretty high level of competence. There are no instructions and the car comes as two big crates full of parts.

You could just slap the kit together and go racing or you could prep the car like a motorsports professional and take your time and take care of the details to build a car that is more durable, easier to work on and more reliable in the long run.

Check out our continuing coverage of the right way to build an NP01 with the guys from StopTech as they have taken over the palatial MotoIQ Megashop to build as ultimate of a spec racer as the rules will allow!

 

Check out our driving impressions of the NP01 press car.

To read about how the build of our car started check this out!

Part two of putting it all together look at this!

Part Three is here!

 

 
When we last left off the powertrain was installed in the chassis as well as most of the interior stuff in the driver's compartment. The boxes of parts are starting to look like something now!
Next, the left side floor was installed so the heat exchanger unit could be installed.  

The heat exchanger cools the coolant and has a water to oil cooler for the engine oil. A duct feeds air from the side pod through the heat exchanger. The floor is made of a marine-grade plywood with a laminated non-porous skin on both sides to make it oil resistant.

 

The wire harness goes from the driver's compartment through the outside to the rear part of the car via these mil-spec connectors. 

The StopTech crew invested in upgrading the basic wire harness that comes with the kit to one using mil-spec components. In our opinion, this is money well spent because the majority of race car failures are caused by plumbing and wiring issues in our experience. Making the wiring as easy to maintain and as goof-resistant as possible will go a long way towards increasing reliability.

 

The breather for the dry sump system is installed. 
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Comments
warmmilk
warmmilklink
Monday, September 12, 2016 11:45 AM
Last pic on page 4, the heim joints on the control arms are oriented with the housing horizontal, wouldn't it make more sense to have them vertical since that's the direction they move in? I realize that these cars don't have all that much suspension travel so they don't need a huge articulation range...

Is there an advantage to mounting them horizontally?
Mike Kojima
Mike Kojimalink
Monday, September 12, 2016 11:58 AM
I don't think it matters since they don't articulate much, maybe the mounting tabs on the chassis can be bigger and stronger.
MDR
MDRlink
Monday, September 12, 2016 6:00 PM
I always thought mounting the front calipers rearward and the rear caliper frontward was for reducing the polar moment of inertia (get the weight towards the CG).

Is this not the case? Can you elaborate on the front caliper mounting design considerations?
Mike Kojima
Mike Kojimalink
Monday, September 12, 2016 6:06 PM
I thought I did.
8695Beaters
8695Beaterslink
Tuesday, September 13, 2016 5:54 AM
@warmmilk, the big advantage of orienting the rod ends horizontally is the adjustment of roll center and anti-sqaut/dive. If you look on the transaxle on the top of Page 4, you can see there are extra threaded bosses for the control arm mount to attach to. These adjust roll and anti geometry. If the rod ends were vertical, they would not have the space to move the arms up and down. The centers of the arms would also be closer together (since you need about an inch of extra vertical space to allow for bolts), which would change the roll geometry. Mike can correct me if I'm wrong, but I believe decreasing the distance between the inner control arm mounts would cause for more roll center movement, which is undesirable.

On the manufacturing/design side, horizontal rod ends also allow for much simpler clevis design. Veritcal rod ends would need an angle-cut clevis to meet up with the flat mounting face of the transaxle/bulkhead. The clevises needed for horizontal rod-ends can be parallel cut which is much easier and cheaper to make. It also means the clevises on every mounting point can be identical, which reduces the number of spares a racer would need to order and carry to each event (it is quite likely each mounting point front, rear, top, and bottom would need different mounts in a vertical orientation. That would be 16 individual mounts to keep track of!). So there is also a cost and manufacturing consideration to consider.

This was a decision we had to make in FSAE. We chose horizontal rod-ends because they were much easier to make and package.
Mike Kojima
Mike Kojimalink
Tuesday, September 13, 2016 10:08 AM
I think it's simple mounting tab space and the ease of making the tabs double shear.
rhocken
rhockenlink
Tuesday, September 13, 2016 12:25 PM
Can you please expand on this "The caliper is rear mounted which helps self-aligning torque and straight line stability" Perhaps with a force vector diagram so I can see what I'm missing. Given that the torque the caliper is arresting is around the axle line, the caliper would have the same arresting force and resultant force on the hub no matter how it was oriented radially.
Mike Kojima
Mike Kojimalink
Tuesday, September 13, 2016 12:41 PM
think about what caster does.
rhocken
rhockenlink
Tuesday, September 13, 2016 4:26 PM
I know what castor does, and I don't see how it relates. The brake caliper is fixed to the knuckle which has the spindle for the hub and thus rotor. The brake caliper clamping on the rotor imparts a torque force on the knuckle around the spindle center line. The same force is applied to the hub irrespective of where radially the brake caliper is.
Mike Kojima
Mike Kojimalink
Tuesday, September 13, 2016 5:25 PM
And the heavier caliper will naturally want to be on the downhill side. On the uphill side the caliper will want to stay at either lock, on the downhill side it will want to be in the middle or the lowest point of the arc.
rhocken
rhockenlink
Tuesday, September 13, 2016 6:44 PM
Great, thank you. Now I understand what you mean. It is the placement of the mass, not the fact specifically that it is a brake caliper
ginsu
ginsulink
Tuesday, September 20, 2016 5:37 AM
You gotta get the caliper in the 6 o'clock position like in F1. After playing with sunroof deletion on my DD, I swear CoG Lowering benefits are more important than the Polar moment. I really hate body roll, surprised no rear sway bar. What kinda alignment on the front, lots of caster? And playing with ackermann?


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