When we first let go of The Flying Dutchman at Fox Lane’s football field over a year ago, we really didn’t know what we were in for. Sure, we knew that our plane could glide pretty well without solar panels in its wings and everything moved when we told it to, but none of us would have guessed that the next year we could watch our plane gracefully loop around a field four times that size. And that’s pretty much what happened.

On August 4th, Matthew, Hudson, and I set out to the humid pastures of Horace Greeley High to put the third version of our plane to the test. Other than a few temporary fences randomly scattered around the field for an unknown reason and the occasional pedestrian, we had found the perfect place to fly. On our timid first test of the practice wings, we covered more distance than we had ever done before. The addition of ailerons greatly improved our control of the plane, allowing us to fly in an unpredictable crosswind.

After flying with the practice wings became more fun than stressful, we decided to switch to the solar wings. Although we were a little worried about throwing of the center of gravity by putting too much weight high on the wings, the solar wings handled very similarly to the practice wings. They were even stronger than we had expected with the improved frame (using a longer carbon rod to hold the wing halves together instead of the short iron one, among other things) and laminated panels. Even though we had a few hard landings, we did not break a single solar panel! Much to our relief, the laminated solar panels, condensation in the wing, and old MPPT did not seem to detract at all from the charging rate of the battery. We still ended up charging the battery faster than we could discharge it, even with sustained flight in a crosswind.

The only real disappointment was that the on board camera (even with the upgraded helical and clover leaf antennae) did not work at all, so we don’t have any onboard footage this time and were unable to try FPV.

Eventually, we realized that what was limiting our flight wasn’t our plane anymore, but our skill as pilots. Hudson and I were too scared to try flying, and Matthew’s only experience with gliders has been flying the solar plane (shocking, huh?). Rather than risk ruining the solar wings, we decided to retire them Saturday evening until we can find an expert pilot to fly for us, or one of us learns to fly gliders properly. We went back out the field on Sunday and flew with the practice wings until we had to emergency crash land into a fence to avoid skewering a Lexus. Even so, the wings and fuselage are only mildly damaged.

All in all, we can go home happy knowing that our dream of a solar plane capable of long sustained flights has been realized in The Flying Dutchman.


-Tighe

It's that time of year again. We are heading up to Westchester to fly tomorrow. We are first going to try out the fields at Horace Greeley School. They have 2 soccer fields and 2 baseball fields all conjoined, so that should provide ample space. If there are too many people there, we will move to a field on West Lane in Armonk, NY which is on a nature preserve. Unfortunately, we were not able to fix our broken MPPT, as the problem seems to be more than just a broken IC chip. We are back to using our old MPPT, but it doesn't seem to be much of a problem because we need the extra weight anyway to move the center of gravity further forward. We are all really excited to get back in the air, and hope to have some long flights thanks to our modifications on The Flying Dutchman 2.0

Ok, first things first. The wings are fully covered now (group picture with the plane soon to come). They look beautiful, not to brag or anything. There are some stylish orange polka dots, and some shiny blue solar cells that are a fantastic blend of cutting edge technology and posh design! However, early last week, when I took the wings to the roof to test their power output, the current coming from the wings to the MPPT had dropped from 1.7 amps (when uncovered) to .7 amps (when covered). We panicked, thinking that the Monokote covering was reflecting too much light, and thus reducing our overall energy production. However, when we took the wings to the roof the next day, the current was back up to 1.5 amps. We think the cloud cover could have made the big difference. The 1.7 amps came with slight cloud cover, while the .7 amps came on a completely clear, blue-sky day. The clouds actually helped to reflect the sunlight back down onto the wings, thereby giving the wings more rays of light than direct sunlight would.

However, while testing the current, it seems that we may have accidentally shorted out our MPPT. It kept going into standby mode and not charging the battery. Upon further inspection, we found that one of the IC (integrated circuit) chips in the MPPT had a small fracture in it, as if it had exploded due to a short circuit. With the aid of a magnifying glass, we were able to decipher the serial number on the IC chip and Hudson was even able to figure out the logo for the company, directing us to their website. We now have 5 extra IC chips on there way from California set to arrive on Tuesday. The soldering of the replacement chips should prove to be our most difficult yet (probably ever for all of us). The pictures below illustrate just how small the chips are. The circuit board that makes up the MPPT also utilizes SMT (surface mount technology) in order to save space. This means that all the electrical components are soldered directly to the top of the board. Older boards have holes for the legs on each component to poke through, allowing one to solder them from the back, in a much neater fashion. I was able to remove the broken chip from the board this afternoon, but not very easily. You never realize how much your hands actually shake until you deal with something that small! We'll yet you know if the replacement chip works on Tuesday. If not, we still have our old MPPT, although that one is heavier and slightly less efficient.

-Matthew

Today we finished covering the tops of both wings with clear monokote as well as covering the first inboard panel on each wing with clear plastic (.03" thickness). The covering took longer than we thought it would to apply, but it went on surprisingly well. The clear monokote is extremely transparent, the only thing we are worried about is the reflection of light. Although the covering is not at all foggy, it does seem to be rather reflective and shiny. This is the same covering we used last summer, but we never really considered this issue. We will perform another test of the array's charging abilities once the weather clears up (it is thunder-storming right now). Only the tests will tell us if the arrays charging current has been decreased. If it has, there is really not too much we can do about it, because any less reflective coverings are too heavy and/or too expensive. Fingers are crossed that the power stays relatively the same!

Here it is, the full solar array. And it works! We tested it with a volt meter, and all the wiring is correct, no mistakes made. We are waiting to cover the wings until after we have tested it with both MPPT that we will be choosing between. There is a slight chance we will take out solar cells to lighten the load if the new MPPT is really a lot more efficient, but most likely not. The wings are pretty light as is. That MPPT is in San Pablo, CA right now and is scheduled to arrive in one week. Can't wait to do some rooftop tests! 

Sorry for the lack of updates, we have been hard at work. On Thursday, July 5th, we finished soldering all but 4 of the solar cells (the two inner/outer cells on each wing). These were all soldered in one day straight, with Hudson putting in the bulk of the work. We only broke one cell in the process, something that could never have happened last summer without the Monokote lamination on the cells.

Our wings have also been painted blue to match the cells. We found clear acrylic rods for the outer portions of the wings to maintain the airfoil shape as well as protect the cells. When connected together, the new wings are extremely solid (and they haven't even been covered yet!). The carbon connecting rod with which we replaced the shorter iron rod provides much more strength because it extends deeper into each of the wings.

We also just ordered a new MPPT (maximum power point tracker) solar charge controller that drops down the voltage of the solar array (when the two wings are wired in series, providing 18 volts). This MPPT is 100g lighter than the previous one and apparently more efficient. The previous one boosted the voltage (when the wings were in parallel, providing 9 volts). We will do a series of tests once this MPPT arrives to verify that it is truly a better choice.

In the meantime, here are some pictures!

-Matthew

We decided that it would be more cost effective to try and cut the solar panels ourselves this time instead of buying them pre-cut. Also, the pre-cut panels were dimensionally inconsistent. After trying (and failing) to cut them neatly by hand with a diamond bit in the Dremel, Matt rigged up a table saw jig to hold the Dremel and diamond bit precisely in place. Although it worked well on the raw panels, it was difficult to prevent them from chipping at the end of the cut. We solved this problem by laminating the solar panels before cutting them. Here's some footage we shot of cutting the panels.

We recently got a shipment of 110 new solar cells that are pre-tabbed. This means the wire has already been soldered to the top part of the cells. This soldering is done much better than we ever could have hoped to do ourselves, saving weight as well as being much neater. We tested different types of covering on the solar cells, and the best seemed to be clear 21st Century Microlite. It is an iron on covering designed for lightweight RC plane wings, but it awesome at adding strength to our solar cells without taking away from power, and only adding a half-gram to the weight of each cell (the new cells are already 1 gram lighter than our previous ones due to the cleaner soldering).

Our test wings are now fully repaired, we have also finished construction on the aileron servo mounts. The mounts screw in, allowing for easy access in case we need to replace a servo or adjust anything. We have ordered 2" aileron stock and are waiting for it before we proceed any further with the aileron construction. We plan to run both aileron servos off one channel using a y-splitter, allowing us to use a helicopter gyro (which we also just ordered) to maintain level flight. This should help exponentially with our landings.

-Matthew

We had a team meeting last week and ordered 100 new solar cells, a new wing kit, a carbon wing rod (to replace the current heavy iron one), and monokote convering. The solar cells we ordered are "short tabbed" which means that the tabbing wire used to connect the cells is pre-soldered to the top of each cell (not the backs). This will make our build much quicker, and save the lives of numerous solar cells which we continually broke last year in the soldering process. We also found that the diamond Dremel cut-off wheel cuts through solar cells like a hot knife through butter. This weekend, I constructed a mini table saw for the sole purpose of cutting 3x6 solar cells in half, making the 3x3 cells that we previously had to order separately at a higher price. Here's a picture of it; I'll upload a video once I bring it to school (all the solar cells are there).

-Matthew

A full year has passed since we first heard that we got the Herzig grant to built the Flying Dutchman and began one of the most defining projects of our high school careers.

And now, we're back for more. Keep an eye out for future updates, they'll be coming.