Friday, December 28, 2007

Airplanes: Chuperosa Part 10

After about 2 years of intermittent building, the Chuperosa is finally complete. All up weight with radio is approx 13 oz.

Sunday, December 16, 2007

Workshop: Modify Your Wireless Rotary Tool For Wired Power

I recently purchased an ultra-cheap dremel-like wireless rotary tool. Of course I got what I paid for, because the battery packs (two were surprisingly included) are low capacity, short running pieces of ni-cad crap. After a full charge you could only expect 10 mins of runtime! I figured I would just have to replace it. Then I found an old AC wall adapter that matched the power specs of the battery and thought about simply opening up the drill and soldering the leads directly into where the battery connects, but after looking at the 2 battery packs I decided to sacrifice one pack for its case to use as a removable plug for the wall adapter. With this setup, it now has the ability to be both wired and wireless. See the pictures and descriptions below. chances are, you could do the same thing with your particular brand of rotary tool. A WORD OF CAUTION: Please make sure the wall adapter you plan on using can provide enough amperage for your drill. If you are not sure what I mean by that, then don't do this project. You'll want to periodically check the adapter to make sure it's not overheating. When you're done using it unplug it from the wall!

Above is the drill, and disassembled battery pack before the simple modification.

Above is a detail of the empty battery case. You can see where the terminals need to be. I was able to clip the battery terminals off the pack so I could solder them to the wall adapter leads. I used a piece of styrofoam shaped like the old pack so the leads would fit snug inside the case.

Above is a picture of the "plug" that allows me to switch between wired and wireless power. Notice my bandaged finger-Be careful of disassembling the batteries!

Tuesday, November 20, 2007

Electronics: Re-Used Cell Batteries

Here's a couple of old cell phones of mine. The batteries (3.7v 900mah Li-On) are in excellent condition, and the phones can be used as charge regulators- so why not use them as flight packs for a small model aircraft or robot? Have any of you done this? I'm wondering how I could build a light battery holder with "precise enough" terminals to contact the battery tabs? All thoughts are appreciated.

Sunday, November 11, 2007

Airplanes: Chuperosa Part 9

Structural construction is now complete. I'll be using microlite plastic covering to finish it up. One obstacle remains however, after the covering and radio install. I'm not 100% sure I have the incidence correct. I made sure the wing saddle matched the prints, but I'd like to measure to be sure, and of course I don't want to drop more cash on an incidence meter. Does anyone have an accurate way of measuring this using a straight edge or something?

Sunday, August 26, 2007

Airplanes: Chuperosa Part 8

The wing is finally complete. It's been a busy summer, so finishing this project is proving difficult- but with this step complete, progress is being made. I still need to add the glass tape at the center, but I wanted to document it at this stage because I think the tape clashes with the overall form. This was my first scratch built wing. It was a great learning experience, but I'm looking forward to my next project being a laser cut kit.

Friday, June 22, 2007

Airplanes: Chuperosa Part 7

The right wing panel is almost complete. The steel straight edges provide a nice emphasis on the wing's taper, which isn't too visible in the previous post. I'm starting to plan the color scheme- there are so many options these days. I need to do some research though before I venture back into the world of plastic coverings, considering it's been over a decade. If any of you brilliant readers out there know of any web resources that discuss covering techniques, please let the rest of us know about in the comments.

Tuesday, June 5, 2007

Airplanes: Chuperosa Part 6

The left wing panel is finally complete. I need to pick up a new scale to see how much more sanding I need to do- hopefully those holes I drilled in the TE will help reduce the weight. If you have any wing building tips, please let me know and post a comment.

Sunday, May 20, 2007

Airplanes: Chuperosa Part 5

This is taking longer than I thought. I forgot that I would also have to make my own drawings. Below is a picture of the left wing panel with 6 more ribs to fit. Notice the steel straight edge at the leading edge- this is the first time I tried this, and it works very well because it not only trues up the LE, it gives you a more solid object to work with, which in turn helps make sure the ribs can be sung without bowing any of your straight lines.

Sunday, May 6, 2007

Airplanes: Chuperosa Part 4

I shaped the wing ribs today. This was the first time I used the stacking technique, and it seems to work well. It's exciting to see this glider finally take shape.

Sunday, April 29, 2007

Airplanes: Chuperosa Part 3

The fuselage for my Chuperosa RC glider is practically complete. It's constructed out of balsa, spruce, and plywood. The open framework took some time, but it does add a unique look. The next phase in this project is to frame up the wings. I need to buy a simple Drill Press first though, so I can make an accurate stack of ribs as described in this previous post.

Sunday, April 22, 2007

Workshop: Build Your Own Mini T-Square

While building the fuselage for my Chuperosa, I needed a way to square up the bulkheads. My regular T-squares were too big for this job, so I quickly built a simple mini T-square. It's easy to make, and if constructed correctly will be very accurate. Below are a few sequence photos with descriptions that will show you how to build one.

These are the tools you'll need. A larger drafting T-square and a builder's triangle. The ridge on the builder's triangle needs to be flush up against the blade of the T-square.

I used 1" by 1/8" bass wood strips from the hobby/art supply shop, and squared it up on the combination tri/drafting t-square and then used slow CA glue, and pinched it with my fingers for a few seconds until the glue dried.

After the glue dried, I cut the long side to match the other side of the beam. As you can see it is perfectly square.

Here's the mini T-square in action, as you can see, a normal drafting type square wouldn't work for this hand launch glider. If you build one, please let me know about it and post a comment.

Sunday, April 15, 2007

Airplanes: Chuperosa Part Two

I have started construction on the replacement wing for my Chuperosa RC glider. Below you can see the stack of 1/16" blanks along with the aluminum root and tip templates. These will be formed into a stack, bolted together, and shaped to conform to the templates. Luckily, my Dad recommended this method, as I was unsure of how to proceed after I destroyed the foam core wing. I found an application that seems like it could work, but since the free version is cripple-ware, I could not be bothered with it. The method I chose should work just fine, and is described in detail here. (Link is a PDF) That link by the way, is an awesome reference and true wealth of knowledge for RC glider builders and pilots alike. The RC Soaring Digest is a great example of the open source
philosophy, and they allow anyone complete and unrestricted access to their archives. Let us know what your favorite spots on the web/library/newsstand are for RC model/hobbies by posting a comment.

Friday, April 13, 2007

Robotics: Infra-Tank!

Here is a 47 sec. clip of my latest bot I call Infra-Tank due to the fact that it is controlled with my infrared stereo remote controller. This is a custom design/build, but is based on the parallax boe-bot. The tank tread kit is from tamiya and the aluminum plate chassis is from K&S Engineering. It uses 2 servos modified for continuous rotation, and is guided by the BS2 microcontroller from parallax. You can build your own by using these directions as a rough guide. I would eventually like to attach a web cam or gripper- but the weather is finally starting to get nice here in MN, so I need to get my airplanes ready! Your thoughts and comments are always appreciated.

Saturday, April 7, 2007

Workshop: DIY Measuring Dividers

Here's a simple tool that I wish I had made years ago. These dividers are perfect for measuring short distances within difficult to reach areas like fuselages and the interior of any built-up structure like wings, and tails. It is far more accurate than a ruler or the dreaded method of laying the piece of wood across the structure and just cutting- a bad habit I finally broke with this tool. It's comprised of two pieces of 1/4" square bass wood, and cut T-pins inserted with pliers. The two legs are connected with a machine screw and washer. Harder wood and better hardware could be used if you like- just remember to pare down the tips of the legs where the pins mount for better accessibility. Do you have any unique tools that you've already built? Please share with the rest of the world and post a comment!

Sunday, April 1, 2007

Workshop: CA Glue Bottle Trick

Tired of your CA glue nozzle getting clogged? Use a scrap piece of music wire (1/32 or larger) with a bit of tape on the end for a little handle, and you can use it as a stopper. I've wasted too many bottles of expensive glue due to frozen tips. This stopper solves the problem. If you have any model adhesive tips, please post your comments.

Saturday, March 31, 2007

Airplanes: Chuperosa Part 1

Here's a 1.5 meter 2Ch. sailplane currently in the assembly line. Called the Chuperosa- it's an old kit with sheeted foam core wings, built up fuse, and sheet tail feathers. Unfortuantely, I was dealt a setback the other week when I attempted to sheet the wings. I was using Dave Brown Southern's Sorghum for the adhesive and after I applied the glue and placed the top sheet on, I noticed it was a bit crooked so I attempted to re-set and destroyed the skin. It was very frustrating due to the time it took to make the skins. I do not recommend using that type of glue. Next time, (if I can bring myself to work with foam cores again) I will use the white glue technique as described here. So now, the next step is to scratch build a traditional wing using the root airfoil as my main pattern. It appears that the company who manufactured this kit is no longer around- if any of you have built or flown a chuperosa, know of any groups, resources associated with this model please post a comment. I will have several more posts on this project starting next week so, as always check back often! Below are the pics of the fuse, and tail assemblies and the front cover of the instruction manual

Sunday, March 25, 2007

Airplanes: Mini Kestral

Here's a small scale RC glider that I recently completed called the Mini Kestral. It was designed by the master modeler Dave Robelen. It has a 38" high aspect-ratio wingspan, and is built completely out of lightweight contest grade balsa. I found the construction article in the now (unfortunately) defunct Radio Control Microflight magazine. Plans can be purchased here. I still need to install the electronics- which will not be easy due to the small size of this bird. Stay tuned for new posts when she's flight ready, along with posts from the field on the maiden flight!

Friday, March 23, 2007

Robotics: Link Crawler

Here's a bot that I built a while back that I named link crawler due to the wonky linkage. It was a bit low-end, but it actually stomped around like it might of had a purpose. It was controlled by a basic stamp microcontroller from parallaxinc, used 6 servos for motion, and was unfortunately sensor-less for its short lifespan due to the fact that this project was an exploration of walking style robots. There's something about seeing a fabricated object with moving appendages that never ceases to amaze me.

Thursday, March 1, 2007

Projects: My Workbench

This was a pretty simple deal. Purchasing and transporting the materials was more difficult than the actual assembly. It is made from 2x4's and a fantastic 7' solid core office door that I scored from work which is covered with a 1/8th" hardboard veneer that was cut to match the door. My friend Eric made this possible with his miter saw and 4 runner, and I suppose his construction experience. I found the reference drawings and info/instructions here:
Below are the sequence photos: