In 2009 we set out to conclusively answer the following question... Can a vehicle be built which can go directly downwind, faster than the wind (DDWFTTW), powered only by the wind, steady state? On 3 July 2010 we established a world record by going directly downwind at 2.8 times the true wind speed with the Blackbird.
Now we have begun to modify the Blackbird with the intention of going directly UP-wind faster than the wind - steady state.
The blades are "done" and fiberglassed. They still need to be painted and sanded, but I decided to go ahead and extend the spars for mounting in our existing hub. Had I been a little smarter, I would have left them sticking out a bit further to begin with, but the extensions will really beef up the roots - so I don't mind.
Next I'll add the fiberglass sleeves over the spar roots so they slide perfectly into the hub and bearing races. After that we'll have to increase the gear size on the rear axle fairly substantially for the upwind runs. Then I'll add a chain guide up top to keep the chain from coming off the upper chain wheel (since it will now be running in the other direction), some minor trailer repair, and then head out to the runway at New Jerusalem on a windy day.
We're still shooting to do some unofficial runs in the next few weeks.
Both blades now have a couple of coats of 3 oz fiberglass. One more coat and it'll be time to fill and sand them for the best finish I can manage. They're no work of art, but because of the CNC machined cores, and now having a little more experience with fiberglass, they're coming out significantly better than the first set.
Soon I'll be fitting these blades to the hub that held the prop blades for going directly downwind.
I built a new table for fabricating the turbine blades from the CNC cut foam cores. This part of the project moves back into my garage since it doesn't need the space for a 23' tall vehicle.
The foam cores are bonded to carbon windsurfing masts with epoxy resin before sanding and fiberglassing.
After a very long sabbatical, we're finally building some momentum on making our downwind cart go directly upwind faster than the wind.
We'll use the same vehicle, and will change only the prop and transmission. The propeller will come off (and will temporarily be on loan to a researcher doing R&D on low speed wind turbines). It will be replaced by a turbine. The turbine will look very much like the propeller, only hopefully nicer, and with the opposite twist and camber
Our resident aero expert, Steve Morris, once again knocked out a design to meet our specs, and a volunteer that's been following the project offered to cut the foam cores on his CNC mill. Pat Enright teaches design at SJSU, and has some experience making large propellers for human powered vehicles.
I expect to get all the pieces in the next few days, bond them to our new carbon windsurf masts, and start glassing again.
On the upwind cart the wind will turn our turbine, and that will turn the wheels, sending us upwind faster than the wind - steady-state. The turbine will also turn the opposite direction from the prop so we can again take advantage of the long left axle to keep us from overturning the Blackbird at speed.
We hope to do some upwind runs before the Summer winds subside, but JB has been traveling almost continuously for Sportvision. This might put a crimp in the transmission rebuild. Fingers crossed.
Unfortunately, the news this time is not happy. We learned today that Andrew Bauer passed on Sept 6. As our blog followers will recall, Andrew Bauer was not the original inventor of the concept, but did build the first successful DDWFTTW cart that anyone seems to know of. He did this to settle a friendly wager with colleague and notable aero engineer A.M.O. Smith in 1969. As we understand, the wager was based on a claim in a student's paper, written 20 years before, that DDWFTTW should in fact be possible. In some small way JB and I have tried to model ourselves after Andrew by doing the engineering and demonstrating the principle - rather than simply proving it on paper.
Over the course of the project JB and I have been lucky enough to talk with Andrew's wife, some of his colleagues, and now his son. All have been extremely friendly, helpful, and enthusiastic. Unfortunately, Andrew suffered from Alzheimer's and was not able to participate in the current round of silliness. But I think he would have enjoyed it.
Well, we exceeded our goal. On July 2nd, 2010 we set a world record going 2.8 times the wind speed directly downwind on the El Mirage dry lake bed in southern California. And then we became so complacent and lazy that we didn't even update our blog. You can read all about it on the NALSA (North American Land Sailors Association) website here: http://www.nalsa.org/DownWind.html
Our fastest run to date was approximately 54 mph. Our best speed ratio was a little more than 3.5 times the wind speed. Of course there are a number of requirements to establish an official record run with NALSA (for example we must be accelerating through the submitted portion of the run). Of the runs we did at El Mirage, the best run simultaneously meeting all NALSA requirements had us at 2.8 times the wind speed directly downwind. Given enough time to make lots of runs in lots of conditions we're confident we would achieve an official run of more than 3X wind speed. But we're plenty happy with the results we have.
"So, one night, I was happily drinking my beer and tending to my inbox of endless boring emails that had be answered but were of no real consequence, when Lester, my landsailing buddy texted me a link to fasterthanthewind.org. Lester knows a lot, and if he says this needs my attention, then it gets it. I am not sure if it was how many beers I had had, or simply the inane nature of the quest, but I laughed enough to email all my friends to share the absurdity of their mission. My heart is split between belittling idiots, and saluting eccentrics, and this downwind quest lay somewhere in the middle. These loonies were pursuing a pointless goal, doomed to failure, but there was some genuine merit in the myth and their enthusiasm.
I dismissed it as utterly impossible. Traveling through zero apparent wind, with no stored power? Impossible. Why would you even attempt it? (Though I'm no stranger to that question myself!) But had I been asked to bet at that moment, I would have just lost a lot of money.
A few months later I actually met the idiots in question and, to my surprise and concern we not only have a few mutual friends, but they seemed to be rather technically credible. But, everyone makes mistakes, and I let them off as decent people with a blinkered view of fundamentally flawed engineering....
A few months later they were claiming success and if it was not for another great friend, Bob Dill, advising that they were actually correct, I would have discarded their claim as an April fool. I thought about the possibility that I was wrong, and then considered that as Bob was getting on a bit and had a bit of a shake with his stopwatch finger, maybe it was he who was mistaken. There was, however, a growing momentum of technical people (who should have known better), saying that these idiots have actually proven that it is possible to travel faster than the wind going directly down wind.
Not content, I had to witness this myself. When I heard it was on for the official record at El Mirage, I jumped on a plane and went to check it out.
The video speaks for itself. These guys are not idiots, but sincere, genuine, technical people who took a myth and made it real. It works. It starts from rest, trundles to true wind speed, then powers to a multiple of about 3 times the true wind speed. Bob will confirm the final number I am sure.
To all fellow skeptics, start baking that humble pie, or eat your hat. Your choice."
NALSA has data sets showing peak speeds of over 3.5x and what we believe to be the best 10 second average of 3.48x.
This does not mean that NALSA will be ratifying a record for that particular run -- there are a host of requirements to be met (wind can't switch directions during run, etc.) before a run becomes NALSA valid.
We are becoming more and more confident that NALSA could ratify a record that is greater than 3x the speed of the wind.
2 days of NALSA testing complete. ~16-18 speed runs in ~12-13 distinct passes -- wind was lengthwise the lake on the first day giving us room run throught 2 sequential 'traps' on one pass.
Every run well over 2x. Most runs over 2.5x. Best runs near 3x or perhaps above. We won't know details of which runs qualify against NALSA rules until they go through the large amount of data and figure out which runs are best documented. There is a fairly comprehensive list of requirements to be met for a run to be NALSA valid and I'm certain that some runs will be disqualified if all the sensor info was not to their liking (wind switching direction too much during the run, etc).
There are reams of data for them to go through from more than 20 separate sensors (multiple gps, wind direction and wind speed sensors) on the vehicle itself, chase vehicle and lakebed, plus multiple video cameras. It will take some time for them to go through it all once they get home.
To say the least we are confidently hopeful that a record over 2x will be ratified by the NALSA BOD.
Pictures, video and more information to follow as we recover from the long days and long drive home.
A special thanks to the NALSA officials who put in so much time, effort and money (they wouldn't let us pay for their travel expenses) to make this happen. Thanks also to the NALSA BOD who saw something interesting in this crazy little project.
Here are the three location options for the Fri-Sun Blackbird testing. NALSA is bringing observers/instruments and we'll be shooting for a NALSA ratified DDWFTTW world record. We're the first to attempt a record in this brand new NALSA class to as long as we are faster than the wind we'll be in the book. We are anticipating however being well into the 2x+ wind speed range and perhaps even into the 3x range with a little weather luck.
Watch the twitter feed down to the right on this page for regularly updated information starting tomorrow, or follow directly on twitter using @ThinAirDesigns. Google Maps of the choices.
******************** Current first choice: El Mirage dry lake. We will leave here tomorrow early morning and arrive there to check out the surface and afternoon/evening winds. We do not expect to be testing tomorrow.
All vehicle access to El Mirage is through the SE end of the lake from Mountain View Rd. There is a day use fee paid at the entrance station. Private planes can land on El Mirage.
********************** Second choice will be Superior lake #3 which is ~25 miles north of Barstow, CA. This lake offers us a larger and less used area, but we are told the surface may be a bit soft this year. If things at El Mirage are too congested for the holiday, we may give this a try. PRIVATE PLANES ARE NOT ALLOWED TO LAND ON THIS LAKE -- FT IRWIN RESTRICTED AIRSPACE SURROUNDS IT. Rental vehicle can be delivered to the Barstow airport and it's about an hour drive from there.
Superior Dry Lakes are located about 20 miles north of Barstow. NOTE: The Army has annexed and fenced Superior Lakes 1 and 2. Take the WESTERN branch of Fort Irwin Road north from Old Highway 58. Turn north off the asphalt at Copper City Road. Follow Copper City Road north to the boundary gate of the newly expanded Fort Irwin annexation area. DO NOT ATTEMPT TO ENTER THE FORT IRWIN PROPERTY. At the gate turn west and follow the new boundary fence road. The boundary fence road will eventually turn north. Follow it until it bisects Black Canyon Road (Unmarked). Turn west on Black Canyon Road, then northwest on the little road that leads to Superior Dry Lake #3. There are NO facilities, so bring plenty of water, food, a spare tire, warm clothes, toilet paper, a shovel, and some shade.
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Third choice and very unlikely at this point is Smith Creek lake bed 25 miles SW of Austin, Nevada. We're driving south first, so only strange weather will force us back North.
Lake access is from State Route 722 at mile marker 17.
All the little details are falling into place -- NALSA officials flying in, magazine article writers on board, film equipment and staff scheduled and ready to go.
Over the next day or so we'll check every bolt and screw on the Blackbird and organize a selection of spare parts (hopefully the right ones).
We roll out of the shop this Thursday morning. Follow our twitter feed for updates as to which testing location we will ultimately be using Friday through Sunday (as needed).
All testing locations will be publically accessible and visitors are welcome.
Friday, we took the Blackbird on a 'show and tell' trip to the engineering headquarters of our primary sponsor, Joby Energy.
Joby has a fantastic group of near 50 bright people working on taking wind energy extraction technology to the next level (literally). It was a fun and knowledgeable group and we had a blast showing them first-hand what their project sponsorship had helped create.
Yesterday we announced the dates for our NALSA record attempt runs. Not a half hour after we announced those dates we got an email informing us that an important business client of our employer will be dropping by our company during those dates. In consultation with NALSA we have shifted those dates down a week or so.
Currently, we are scheduled to point the truck out of our shop on the morning of July 1st with the Blackbird in tow.
Depending on weather and surface reports between now and then, our current location options remain Smith Creek NV, El Mirage CA, and #3 Superior lake CA.
After quite a period of discussion and schedule shuffling, we now have official dates for our NALSA record run attempts.
The runs will be attempted at Smith Creek, Nevada from June 25th through the 27th. If weather/surface conditions dictate, the effort may be moved south to the El Mirage lakebed in SoCal the following week.
NALSA (nalsa.org) has put together a set of rules for the new class. We haven't seen the final version yet as I believe they are in the process of BOD ratification at the moment, but we know what they contain in princple. I will publish them here on the blog when we get a copy.
Technical Guru and former land speed record holder Bob Dill will be the point guy for NALSA along with other NALSA BOD members as observers.
Met One Instruments , a very cool company in Grant's Pass Oregon that makes very high end and accurate meteorological instruments excitedly responded to the challenge and have jumped in full bore to help us document our NALSA record runs.
We just received from them 3 stunning 034B combo instruments that will be mounted on the Blackbird (2) and also on the chase vehicle (1). Compared to the Davis instruments that we have been using, these beauties appear to be made by the Gods -- the smoothest bearings I've ever seen and perfect mass balancing on the vane (critical to our moving application) After confirmation testing by NALSA, the output of these calibrated instruments will be transmitted back to the data base station (manned by Nalsa official) to determine the speed and direction of the winds local to the vehicle.
Accurate instruments are key to any record that is based on a wind multiple so we are extremely grateful to Met One Instruments for this wonderful and generous contribution to the project.
Here is a graph of the gps/WS data for our last two runs at NewJ:
Blue = relative WS from vehicle Red = GPS speed output
1: towing Blackbird upwind to N end of runway. 2: positioning Blackbird for run 3: waiting through low wind cycle 4: pushing by hand. 5: vehicle at WS 6: peak speed 7: reload at S end of runway and then repeat
A great Sunday of non-destructive testing. The runways at NewJ are too short to let the Blackbird truly stretch it's wings, but we still were able to document 8 runs with the fastest just over 2.85x in a 13.5mph wind.
More pics and then some video once I get on a faster connection.
Just in time for our tests on the NewJ runways -- the new drive axle ratchets. Just like the previous and less robust) versions, these act as a form of 'differential' to keep the axle from binding as we turn and allow us to reverse them to tow the vehicle without the prop spinning.
We're going out for runway testing this weekend and we'll see if we need anything more added to that lever system. For accuracy on the upper end of the pitch range I might want to mill some sort of 'gate' system that allows the pilot to adjust one degree at a time by feel. We'll see.
The handle had to be removable to enable entry and exit for the pilot -- turns out the handle from my angle grinder was perfect and threads on and off.
The front hub linkage for the variable pitch is now done. It operates nicely from the cable in the cockpit. Next I work on the lever assembly for the pilot.
The 'thru-propshaft' VP adjustment mechanism is done. There is a long push/pull cable that runs down the inside of one of the pylon fairings and up to the pilot controls (which I build next).
Chris also hollowed out top fairing cap so it fit's nicely
Chris also fitted these Coroplast bits over the back axle structure. The half moon openings are there so we can reach in and operate the axle ratchets and we'll likely tape over them for the record runs.
As we mentioned in a previous entry, apparently one week of cure time wasn't enough before we melted the foam out of the spinner as the acetone attacked the glass. We had the templates still so we decided it was quicker to build a new one than to fill and sand the wrinkles on the old.
Here's Chris putting the first layers of glass on the new one.
Other than the head/helmet, the pilot will be covered with a sewn up lycra piece stretching between the 'dash fairing' and the 'engine cover' and over the pilot's shoulders.
