Off to Playa

New shoes

Off with the pavement tires and on with the desert knobbies.

Push it real good

Here is a shot of our top speed run with the prop (40mph).

Notice that 'popping' sound as the vehicle goes by the camera. That is our second prop shaft ratchet letting go. Last time (on the dyno) the failure mode was the lightened hub itself. This time, in a strengthened hub, it was the ratchet itself.

We've taken the prop shaft ratchet out since we don't need it for now. With the hub still OK, we could have popped in another ratchet (I still have the one from before) and just kept it to 35 and below, but we've opted to just bolt it up tight for this trip. The ratchet was there for when/if we build the spool drive and isn't needed with the chain so we'll lock up straight

Add that spinny thing

After we were happy with the chassis dynamics, we threw on the propeller and slowly increased the speeds.

Here we get up to 30mph

Bob and Weave

Before we allow the vehicle in the grasp of the wind on an open surface we wanted to do a few vehicle dynamics tests. With that in mind, we spent much of Saturday at the New Jerusalem taxiways, first slowly increasing the speeds of the vehicle without the prop installed run by run.

These runs in the video are our later ones and have Rick at about 50mph and trying to upset the cart through steering inputs.

Brakes, steering and general stability proved excellent. There is a bit more brake disc squeal than I was expecting ... I'll do some research on the bike forums and see if there is an answer.

She ain't heavy

When it comes time to do the record runs post shakedown, we may want to go with a very light pilot. Rick's wife Monica has volunteered and as is the procedure for all hired gun drivers, she came in for her seat fitting this evening. :-)

She can't be more than 95lbs dripping wet and she sure would be aerodynamic.

Braking wind

On the eve of our vehicle dynamic testing at New Jerusalem taxiways, I fabricated, installed and cabled up the primary brake lever. The adjustable stops at the base of the lever keep it within the limits of the brake assemblies at the rear.

These brakes will be the ones normally used to slow the vehicle -- the brake set on the front wheel is just a totally independent backup used only in case of emergency.

Two is better than one

The calipers on the drive axle rotors are now mounted. Tomorrow I'll install the last caliper on the prop shaft, fabricate the brake lever and cable them all up.

Wide load

We added the two extra bearings, replaced the aluminum axles with extended steel ones (added 15lbs over the aluminum ones unfortunately) and then load tested the rear assembly.

We're happy with both its strength and also the bit of 'suspension' that the slightly flexible chrome moly cantilevered axles give us.

Up to this point we've kept the vehicle in its narrow configuration so it would fit on the dyno and take up less space in the shop. We widened it out for its upcoming first open surface tests.

Nosing around

In prep for our trip to New Jerusalem on Saturday, Rick put together a pair of mating surfaces to push the vehicle around on the taxiways.

Done in front

Fender mounted, footrests installed, steering stops machined and welded in place, brake cable and guide ran and caliper adjusted.

We'll be taking the vehicle out to the New Jerusalem taxiways early Saturday morning where we can push it around in no wind to get a feel for its dynamic behavior. We'll be in the wider rear axle config for the first time at that point. We'll test brakes, etc with planned runs up to 40-50mph. We can then return and spend Saturday evening / Sunday morning making any adjustments we feel we need.

Steering complete

We finished up the steering linkage tonight. All that is left up front is to run the brake cable, loctite everything and install a pair of footrests.

Front caliper mounting

I'll work on the other three mounts tomorrow evening, but it was nice to get the first one out of the way and learn about the adjustment system of this particular model.

Travel ready

This evening Rick worked on the saddles and travel mounts for the prop and the tower. The propeller will be removed from its shaft and layed under the tower as shown. We'll pad everything up with pipe insulation once its all fabricated.

DDWFTTW for hours on end

We got off a full weekend of dyno testing.

** Full range of speeds (up to 140% of design)

** Full range of AOA (from zero tip to 20+ tip)

** Full range of HP input (up to 2x design).

No runs, drips or errors.

Are we 100% happy? -- that never happens - especially with a limited budget, but we're feeling very good about being ready for the trip to Ivanpah.

From what we learned on the dyno we'll finalize our chain drive system. Additionally we're going from the weight saving aluminum axles to steel. We came to suspect that the aluminum versions weren't going to hold up as well as we were told they would. Don't want to risk a break of an axle in the desert. Steering linkages and brakes will be my focus the next few evenings.

The very good news from this dyno round was that again, at every AOA, and every RPM (within the limits of our motor of course) we were pulling forward with enthusiasm.

Sit down!!

Rick's new masterpiece in use by my lovely partner Kathy.

Really, he only does macrame' to relax

Who knew?

Just happy to be a part of all the madness

Ken Milnes (long time VP Engineering for Sportvision) has kindly stepped up to take one thing off our plate -- an RTK survey of the Ivanpah playa. Ken is the inventor and primary developer of much of our proprietary RTK capabilities here at SV and as such is perfectly suited to setting up the survey system.

The purpose of the survey is of course to know the vertical profile of the lake bed -- this will help us make sure we're not polluting the results by running downhill. We of course expect the bed floor to be pretty damn close to perfect, but it's just good to know.

A few days ago he pulled one of our in-car systems out of the Indy mobile production unit before it headed out for the season. The hardware we'll be using on the playa will actually later be installed and running in one of the racecars during the upcoming Indy 500. We'll try to keep it below 250mph. ;-)

Here Ken is holding a telemetry antenna that will be used to communicate with the base station beacon during the survey.

Sometimes slower is better

With the straight line, directly downwind nature of the craft, we have no need for fast response course correction. In fact we want extreme straight line stability in our steering.

With that in mind we installed an industrial damper aft of the wheel.

A little more meat on the bone

After getting another kart hub in, I fabricated a ratchet hub to replace the one we broke on the prop shaft. Same as the last one except I didn't mill off the flange. It was this thinned down material that sheared off last time.

Down the stretch

We've had an unspoken (blog wise) goal for the last two months -- the vehicle running on the Ivanpah lake bed during the last full week of March. It's not a random date we picked ... the NALSA (http://www.nalsa.org/) is holding their premier yearly 'Americas Cup' landsailing event on those dates and in that venue.

Ivanpah is the playa where almost exactly a year ago the sensational Greenbird (http://www.greenbird.co.uk/land-record) set a new world wind powered land speed record of over 126mph. NALSA is the ratifying organization for such records here in North America.

Starting last year, we have been in discussions with the NALSA BOD regarding the possible addition of a DDWFTTW landsailing class and record ratification procedures. In January they suggested that we bring our vehicle to the event in Ivanpah where a good number of the BOD members will be. This would give them an excellent opportunity to see the vehicle first hand for themselves and provide a more hands on knowledge base for further discussion.

We accepted the challenge even though it meant moving up our construction schedule by almost a full month. We've been charging hard to make this date and it's all looking good at the moment. One week from now we should be well into the first open surface shakedown runs of the vehicle.

In a step beyond the dyno testing, we hope to accumulate another level of understanding regarding the vehicles dynamics which will help us prepare for our record runs later in the spring. The weather has been a bit wet on the playa so we won't know how much actual running we will get until we arrive. Fingers crossed for good weather and a solid surface.

Snap, Crackle, Pop

Soon after fixing the shear pin, we blew up the most highly loaded of the ratchet hubs. The ratchet head itself was fine, it tore out of the housing that I machined.

Several good things here:

A: No damage other than to the hub itself
B: It's easy for me to machine another more substantive hub
C: The propeller was already absorbing almost 2x the design HP before this happened.

All in all an easy fix and under field conditions we don't expect to ever load the system this high again.

Shear pleasure

Our first minor casualty was a shear pin in the prop shaft. The components in this part of the chain are under the most torque load of all. We quickly replaced the soft pin with a harder grade 8 variety and I commented that now we could well break something more expensive. Turns out I was right.

Let's show some restraint here people

Enough excess thrust was generated *after* achieving windspeed, that the dyno was dragged down the parking lot several feet. To keep it in one place, we finally tied it off to the pick truck. The dyno is not on wheels btw, but skids.

This result is completely contrary to the oft quoted theory that no thrust can be generated at windspeed

Uphill, both ways

During some of the testing we loaded up the front of the vehicle and tilted the ramp to force the vehicle to climb as it advanced to the stops. By positioning the stops to start the vehicle axle aft of the dyno axle, the rear wheels were also forced to climb.

The vehicle advances under all conditions.

Before the storm

A few pics from the setup and prep before firing up the wind.

Picture updates to come

In addition to the videos I just posted, I've got pictures as well. I'll get to that after dinner.

JB

Prop shaft break

We moved the pitch to 20 degrees and ran the ratio up to 20/65. First we sheared the grade 2 'butter bolt' that engaged the hex drive to the ratchet hub. We pretty much had the motor maxed out power wise (6.5hp) when that happened so I was hopeful when we replaced that with a grade 8 bolt that we wouldn't break anything else. However before we fired it up this time I said to my buddy Jerry "well, with that soft shear pin gone, now we can break expensive stuff".

It almost came true.You'll see in the video that I fucked up and engaged the idler on the motor drive waaay too fast and I'm sure that's where I blew the side out of the ratchet hub (carnage pics on the blog later). It only lasted a short time and I never got close to max throttle before it blew up.

High speed dyno test

At about 115 rpms and still with the AOA at 15 degrees. Design speed is in the 120 range

First dyno test

This is the first spin up of the cart on the new dyno setup. We were at 15 degrees AOA and were running our slowest gear (15/65). Design point is 20 degrees(tip at static) and 23/65.

Even with the Honda engine nearly idling the vehicle immediately pulled to the front and held against the stops. (for those who aren't up on what that means, it means that the vehicle is going ddwfttw at a very low windspeed -- a good sign of our overall system efficiency).

Pickup work

There were several bits that had been being put aside that we worked on this evening. We made the final thrust box stiffening brackets and installed them. Rick installed the RF board and wired the load cells in the hub and on the chassis. I drilled the prop shaft for a safety pin. We applied Loctite to about a thousand bolts and cap screws. On and on.

Bright and early in the morning we'll be spinning the rig up on the dyno and we'll find out how good or bad we've done both with our drive system and propeller.

DownHonda faster than the Honda

Finished up the dyno mid afternoon. We decided against setting it up outside as the remaining daylight hours just seemed too few. Instead we spent the rest of the day applying loctite and detailing odds and ends that had been put aside.

Dynomight

We fabricated the skeleton of the dyno tonight. I was supposed to pick up the pulley/shaft combo today from the machine shop where is is being lathed, but they were a bit behind and we'll have that in the morning.