A Walk Along Glider (with CNC’d ribs!)

Through my contacts at the Owls Head Transportation Museum, I was introduced to a stick and tissue “Walk-Along Glider.”  What’s a “Walk-Along Glider”?  Essentially, it’s a very light aerofoil that flies on the air that is forced up over you as you walk.  The concept was patented by Tyler MacCready (early pilot of the Gossamer Condor, and son of it’s chief engineer Paul MacCready), and frankly it’s pretty neat.

The plans for the Club Racer 2007 plans I based my model off of can be found here.

Mine differs in that I didn’t feel like drawing and cutting the fuselage out of 1/32″ balsa sheet, so I substitute a 1/8″ square stick of balsa the same length of the original fuselage.  I wasn’t comfortable in my ability to glue two 1/32″ flat plates together at a 90 degree angle, so I made my tail out of 1/8″ sticks with a tissue covering.  Now, let’s get to builder her, shall we?

Ribs
The plan specified slicing the ribs out with a drafting curve.  I have no such tool, and tried cutting a few out freehand.  This was a total no go.  They are so thin (with spar depth of 1/16″) than any deviation from the curve simply cut the rib in half.  Not to be discouraged, my Dad is also a hobbyist, and built a CNC machine for kicks several years ago.  He uses it to make signs for gifts, and occasionally attempts something commercial.  (For those interested in home built CNC machines, I suggest www.CNCzone.com)

So, I drew a simple outline of the rib in NX6 and converted it into G-code using Vetric’s VCarve Pro.  Then it was off to the CNC machine, as can be seen to the left.  It took a few tries to get the cutting path right, as the material was so thin.  In the first pass all of the ribs broke, but during the second attempt we cut deeper into the backing material giving the piece a little more support, as well as placing a little support past the halfway point once the bit passed by.  This gave me 12 good ribs to use!

As you can see, the machine cut the spline (the curve), and then I removed them from the blank using a razor.  This also gave me the straight edges I needed to glue them to the spar.

This wing needed to be constructed in three segments because it has polyhedral (i.e. the flat center section and upward slanting outer sections).  To do this, I laid out a piece of parchment paper over some foam core board and drew two parallel lines 2″ apart.  The spars are held down with pins as can be seen in the picture, and it was relatively straightforward to drop the ribs in and glue them in place.  I used Loctite brand Super Glue Control Extra Time and was very pleased with the results.

At left is the end result of the center section.  Simply repeat with the additional two outer sections.  To attach the three sections as the original author drew would require lots of fancy cuts, though it would be the strongest method.  However, because I didn’t feel the need to calculate out the angles, I simply set the wing sections on the plans and sliced the spars of the outer sections such that they would nicely meet in the inner section at the correct angle, and glued them.  This results in less surface area in contact and a weaker bond, but it has worked reasonably well for me.  Should this joint break when the glider crashes (mine has) the tissue does a good job in keeping it in alignment so it is easy to glue back into the correct shape.

One outer section attached

Covering the wing is straightforward.  Simply cut a piece of tissue paper to about the size of the wing.  Coat the top of the wing lightly (glue is heavy stuff at this scale!) with Elmer’s glue.  Stick the tissue paper on, and allow it to dry thoroughly (if the tissue is still wet with glue, it will likely tear), then cut off the extra.  Do not use superglue for this task! It doesn’t stick nearly as well to the paper and wood, and is a general mess, as it is very good at sticking human flesh to paper.

Instead of cutting out the fuselage and vertical stabilizer per the plans, I modified it to take the lazy way out.  I used an 1/8″x1/8″ piece of balsa as my fuselage, and two struts covered with tissue paper as my tail.  This made it easier to glue the horizontal stabilier as well (which I did make per the plans, except I beveled the front edge as opposed to rounding it.

Once it was all set and done, my initial test flights were appalling.  It didn’t fly, it simply flipped over and looped to the ground.  I didn’t have any clay to use as a weight, but I did have some scotch tape and a penny, which served the purpose well.

Unfortunately, I don’t have a large enough space to test fly it at home.  It seems to require a pretty good clip to keep airborne, a nice run seems to do it.  Unfortunately, it requires very still air, so it’s almost impossible to do outside on the coast of Maine (it’s very windy here!).  So, I have yet to fly it as a walk along glider, but it’s made some pretty decent flights across my living room, and has survived a large number of crashes!

(See top of the post for finished craft!)
I also apologize for the lack of decent pictures/video, my camera is at school so these pictures were taken with my cell camera!

Nannie’s Favorite Recipes

For Christmas I wanted to give my sister a unique gift that she could use. Being the general cheap skate that I am, I also didn’t want to spend a fortune. My sister is getting into baking and cooking lately and she requested cookbooks for presents. My grandmother makes some of the best stuff around so I figured why not ask to see her recipes? So, I began typing up most of my grandmother’s recipes which have been collected and refined by dozens of ladies around town for years and years. I printed them off and put them in plastic sleeves in a binder to ensure that they wouldn’t get messy or wet. I also figured it is nice to backup some of these timeless recipes in a digital format.

I wish I’d taken a picture of the binder but here is the digital format of the recipes for the cooking inclined.

Nuzzo Recipe Book

A Holiday Break Update

Before break, I made a little list of things I wanted to accomplish. A few of these things included:

• Read Saving Sammy
• Learn CAD
• Assemble parts list for LED matrix
• Search for Elon Musk on Omegle

Not all of these goals have been met yet (there’s still a few days left and I think I’m making progress in Omegle search). I actually did read Saving Sammy, I completed a Solid Edge tutorial and kind of got some semblance of a list together for making my LED matrix work. Despite not really completely most of my plans, I have been distracted (as usual) by other unexpected tasks.

My sister’s powerbook G4 has hit a fairly major problem, the power connector board has given out on it. So, I decided to see if it was a simple fix that could save her some money.

Putting this all back together should be an adventure.

I found a great guide on iFixit, I didn’t use it until I got stuck toward the end but it definitely came in handy to tell me what size Torx bit i would need to get the board out. Nothing was obviously poorly connected and I did some continuity checks with my multimeter, I also reset the power management unit following these instructions, but didn’t seem to fix the problem. We ordered another board and it is on it’s way home. I’ll have to finish it another time. Putting everything temporarily back together was quite hilarious. Where does that screw go again?….

In other less technical news, I sold my first item on Ebay. My old 5th generation Ipod that would not play out of the headphone jack. I was surprised to get $49 for it, I suspect someone will take out the screen, battery and/or hard drive and put it in their Ipod. Not bad though for something I was considering giving away.

It’s always great to be home for the holidays, one of my favorite things to do is make a family trip(s) to Marden’s. This time I made out quite well, scoring two 9.6V batteries and chargers for $1.99 each and a police scanner antenna for $.99. I even succeeded in finding a comically big ratchet, unfortunately I didn’t buy it… one only has room for so many comically big things.

Yes all four of my fingers do fit through there.

Well, this post is a little late as I am back at school and just getting back into classes this week. Break was nice but I am glad to get back into the swing of things.

Renewable Energy Christmas

My wind turbine is currently enduring it’s first winter in Aroostook county. The light that was installed on the tower originally required a ballast to ignite the bulb, little did I realize that my inverter didn’t like this very much. Modified sign wave inverters should never be hooked up to purely inductive loads (eg. a transformer or ballast), a couple of burnt out inverters later I realized this. Apparently the electrician was too busy to install an incandescent alternative before winter so it looks like we’re stuck with no light for a while. In the meantime, the landowners decided to use the energy to power their christmas lights (which they strung up the tower). A great use of the power if you ask me.

I requested a picture immediately, apologies for the low resolution but they say it looks great at night!

Wind powered Christmas lights

Interesting Projects

RPI takes an extraordinarily long Winter break.  I’m leaving my dorm room on Friday (8/18) and won’t return until (1/22ish).  I want to be an engineer when I grow up, but outside of the FIRST Robotics Competition, and restoring aircraft at the Owls Head Transportation Museum. I haven’t had a whole lot of hands-on experience.  I spent a couple of weeks at Fisher Engineering in high school, but most of my work experience has been in an office.  I helped organize a $1.5 million car auction last summer, which was pretty awesome (and I will hopefully be working their again this summer), but it’s not engineering.  After all, it doesn’t make much sense to hire a highly skilled accountant to lead the design team of the next Space Shuttle.

So, I brainstormed some things to do.

CAD an airplane.  A really old airplane.  WW1 Aero, is a highly informative magazine on the early aeroplane, filled with both stories of the early aviators and technical goodies.  Sadly, they may have printed their last hard copy issue, but they maintain a list of drawings nontheless.  Not quite sure, which airplane, I’d like to do, but I’ll need a full set of drawings.  Right now the front runner seems to be the 1909 Wright Military Flyer, as it has complete drawings.  I’d like to do something a little less well known, but I’d gladly settle for a Wright.

CAD a rotary engine. Rotary engines were the gold standard of aviation from 1909-1918.  Airplanes need power to fly through the air, and to get that much power, you need engines that generate significant amounts of heat.  They needed some sort of cooling system, and water cooling was simply too heavy.  The Seguin brothers from France developed the rotary engine.  The cylinders are located radially around the crankshaft.  However, instead of mounting the engine block to the airframe, they mounted the crankshaft to the airframe!  That is, the cylinders spin with the propeller.  Scroll down on this page and look at the big picture for a still of one in action (this is a slightly different engine.  I would CAD a Le Rhone 80 HP, they built a 100 HP Oberusel).  WW1 Aero has the full set of drawings for an 80 HP Le Rhone, which is what leads me in that direction.

Human Powered Flight. Okay, so this sounds really crazy.  But I’m quite convinced it’s not out of the realm of possibility.  Jesse van Kuijk just flew last year, doing almost all of the work himself.  He’s 19 and started when he was 17.  I’ve emailed with him a few times, and also Bryan Allan, pilot of Gossamer Condor and Gossamer Albatross fame.  No doubt it would be a huge amount of work, and probably span the next two summers.  Luckily, most of the “hard” things (airfoil, basic structural issues) have been done before.  It would also be undeniably cool.

Rockets I lurk on the aRocket mailing list.  If you are at all interested in amateur rocketry, I suggest you google it and join.  Lots of really smart people doing really incredible things.  It’s a lifelong goal of mine to build a liquid propellant rocket, but building one is a little expensive for a poor college student.  Perhaps some early design work?

First Lego League, VEX Scrimmage and Launching T-shirts at the Civic Center

This past weekend the Black Bear Robotics club made it’s way to the First Lego League Event in Augusta, ME. Besides getting up at 5:30AM to get to the event on time, we did a lot of work at the event. I was a Mechanical Design Judge and got to check out some of the good and not so good designs by the middle school students competing.

Also, we setup our VEX field where we had 12 teams participating in a scrimmage in preparation of the Maine VEX Championship. Overall the kids participating had some great robots, one with an elevator and another with a sort of duel vertical conveyer system.

Also, the t-shirt launcher was on display and in demonstration. We got to fire it into the stands at the civic center much to the enjoyment of the kids. It got a great response from the crowd despite the bugginess of the tilt for the barrels. We dialed it down from 100 psi (which hit the back wall of the students section at the Alfond) to 65 but still got pretty good range.

Checkout Black Bear Robotic’s Youtube account and check out what we’ve been up to.

A high school student talks with a robotics club member

Posters for the Aeronaut

USS Akron above my desk

Whether you’re a pilot, aerospace engineer, student, or just a random person on the street, it’s hard to ignore the majesty of a flying machine.  It’s always nice to have posters to hang on your wall.  Posters from Walmart or another big box store are pretty generic.  Luckily, if you like flying things, be they airplanes or rockets, the National Air and Space Museum’s Archive Division has the service for you!  They’ll ship you technical drawings for incredibly low prices.  While they are essentially large black and white photocopies, they still look fantastic.

List of Drawings

Order Form

Shipping Costs*

*Regardless of how many drawings you order, you’ll want them shipping in a tube to avoid the creases.  So, you might as well order at least $20 worth of posters!

Micro Wind Turbine Test

For my ECE 101 class we had to make an invention, although it didn’t have to be electrical. The first thing that came to mind was a small wind turbine. Basically, I wanted to make something that could be mounted on the window of a school bus or a greyhound bus so people could charge their electronic gadgets with ease from their seats (assuming they don’t have access to any other power source from the engine).

After running some calculations I found that this could be a pretty fun and challenging problem to work on. I would need to make a generator that would work at very high wind speeds (upwards of 80 mph) to ensure I had a little bit of a margin of safety. I figure a typical greyhound bus probably doesn’t do much over 85, figure in a bit of a headwind and it could probably experience a bit more than that.

Barley lighting an LED with the power from a fan. The turbine would light 4 in a 25 mph wind though.

After running some calculations for a 3 inch diameter rotor I found that my main problem would be making the whole system inefficient enough to not over charge common electronics and blow the stator all together. Originally, I wanted to take apart a muffin fan and rewind the stator coils to suit my needs. However, there isn’t much room inside the core of the muffin fan that I had on hand (1.25watt fan) and the number of turns I would need to reach charging voltage would require a smaller wire than I had (or so my professor thought). I took his advice for a lot of reasons (mostly because of a time deadline).

My group member and I mounted his small fan blades on a motor in my room and decided to just give it a shot. After a quick test on the multimeter we achieved about 19 volts (no load) so we threw an automotive blinker lightbulb on it.

Automotive bulb attached

Here are the results: Micro Wind Turbine Test

Updated From A Blackberry

Yeah this is an update from my phone eh?

This is the 12×16 LED matrix I soldered together. I haven’t settled on what I am going to have it display just yet but I will post my progress.