Tuesday, March 31, 2015

Hitec Hawkeye Foam Glider Fun

On recent visit to my local hobby shop Everything Hobby in Rochester Minnesota one of the employees pointed to a small foam glider hanging in a window and thought I needed one. It comes as a free flight glider that I think would be great for kids to throw around because the EPO foam normally just bounces no matter how hard you crash it. Right away I had thoughts of installing light radio control gear in it for slope soaring. It turned out the display model was the only one they had but more would be coming in.

When I returned to the hobby shop I was also shown an electric RC version of the glider that comes with a brushless motor, ESC, and servos. It is setup with rudder control and I wanted to use ailerons so purchased the free flight version. I planned to fly it free flight to start with anyway.

Assembly is so quick, just slide the wing and stabilizer into the fuselage. I threw it around outside of the house over still snow covered ground. It had a pretty good glide for a glider with a fat fuselage and weighing about 54 grams according to my scale. 

Last evening the wind was rather light and the snow was gone so I tried more hand launches in a park. After a few hand launches which went a fair distance I thought I would try a discus style launch. Spinning around and whipping it into the air by grasping one wingtip and releasing got the glider pretty high, but the glider would stall at the top and head straight into the ground. There was never any damage, it would just bounce. 

After bending the surfaces some and adjusting my launch technique I had some flights where the glider recovered at top of launch and went into a pretty good glide. It seemed best to discus launch so that it never climbed at a steep angle. Like most toy model airplanes there appears to be insufficient dihedral.  

I would like to try to catapult launch the glider free flight before the RC conversion is attempted. If you cannot find this glider locally, a check online will find many sources.

Bill Kuhl


Hitec Website

My Last Launch Discus Style

Wednesday, March 18, 2015

PowerUp 2.0 Capacitor Power Unit for Paper Airplanes

My Background on Capacitor Powered Free Flight Airplanes

When the first PowerUp unit came out for free flying paper airplanes I thought this something I just had to try. In the past I have bought or built various free flight model airplanes powered by a capacitor and found the thought of getting it to perform just a little bit better very fun. For whatever reason I did not order the first version but when the PowerUp 3.0 for radio control became available I ordered one of each.

PowerUp 2.0 Capacitor Paper Airplane

PowerUp 3.0 RC Unit

My first capacitor airplane was sold in toy stores by Estes, it was light, small, and flew fairly well. After buying another one, I put the power unit from the first one on a very light balsa and tissue covered airplane. It flew a couple of circles indoors and then there was too little power left to stay airborne.

Estes Capacitor

Balsa Airplane Using Estes Components

After this I purchased another capacitor airplane at a toy store that had a gear drive spinning a larger propeller, it was fairly heavy but the power was pretty good. Stability of the little yellows low wing foam plane wasn’t the best, with some tweaking I did get some fairly good flights.

My Wright Capacitor Design

Student Designed Capacitor Airplane

My next experience with capacitor powered airplanes was to design a balsa and tissue airplane that conformed to the rules for the Wright Capacitor Science Olympiad event. With a working airplane I was able to coach a student my email so she could create her own airplanes for competition, see my blog post about this.

Observations of the PowerUp 2.0 Unit
On my scale the entire PowerUp 2.0 unit weighed about 6.3 grams. The weight is distributed with the heaviest component the capacitor and plastic clip on front and the electric motor and propeller at the other end. It is not possible the change the distance between the two components because of the mounting on a carbon rod. 

PowerUp 2.0 Components

In designing an airplane normally the nose is shorter and carries more weight and the tail needs to be as light as possible to balance. Paper airplanes tend to be a delta type of wing with more lifting area to the rear which should be better with the weight of the motor in the rear. From the ideas I have seen of other foam plane designs for PowerUp, twin booms are used so the motor/propeller can be slightly forward of the tail surfaces without interfering with the propeller. That is what I plan to try next.

Without making any thrust measurements and from what I have seen, the amount of thrust produced by the tiny propeller on direct drive appears to be minimal. For comparison just feel the air movement behind the propeller and feel the air behind a 6” diameter propeller spun by a loop of rubber, no doubt more thrust from the rubber power source. Therefore the airplane will need to be light, produce a fair amount of lift yet not create too much drag.

Paper Airplane Attempts
After receiving the PowerUp units I folded the paper airplane design given in the instructions with the 2.0 airplane. After much tweaking of the paper tabs I never was able to get a flight much longer than 35 feet. It appeared that as the airplane was starting to show signs of level flight the paper would bend and the plane would spiral into the ground.

PowerUp 2.0 Added to Foam RTF Glider

Using the Foam Airplanes I Had
My original intent was to put the unit in a foam model airplane so I started trying to put the PowerUp on some the foam airplanes I already had. First was a ready-to-fly foam glider that appeared to be about the right size and felt fairly light. I bent some paperclips to attach the unit on top, it would extend the glide slightly but never would climb.  After that I found a canard glider I built from foam plates and a plastic straw, not enough wing area, same for a similar constructed glider but this required nose weight to balance.

PowerUp 2.0 on Canard Foam Glider

Next Steps
At this point I am searching the Internet to see what other people have done for better success. There is a guy on YouTube known as GrandDadisAnOldMan that had a couple of videos on a twin-boom airplane built from foam plates that with some adjustments he got to fly rather well, I am going to attempt a similar airplane.  I also found a video of someone that had built a better paper airplane with larger wing area that flew pretty well. This has motivated me to try building from paper again also. If I can achieve some success with the free flight capacitor unit I will attempt experiments with the PowerUp 3.0 radio control unit.

So much fun experimenting with this, I hope to hear from other people working with this.

I tried another paper airplane design and put new batteries in the charger. This plane flew better than previous design but still would not climb, only flew level.

Bill Kuhl

Related Links

GrandDadisanOldMan Great PowerUp2.0 Flight  - in this video he was getting goods flights at the end

Thursday, March 12, 2015

AMA Maxi Jr Free Flight Perfect From the Start

I was so lucky to receive a kit for what might be a very good second model for rubber powered free flight known as the AMA Maxi Jr. Searching for the kit on the Internet the website for RN Models was currently down, I did notice kits are available on eBay. This is a printwood kit in that pieces like wing ribs are printed on the wood, not die-cut or laser cut. To me the wood for the ribs felt heavy so I replaced just the ribs with lighter wood. The fuselage is a rather large piece of balsa but it appeared to be rather light in weight.  During construction and after covering I weighed the different structural components of the airplane, the end result was an airplane under 20 grams without rubber.

Update : Ken A. found this link to Penn Valley Hobby for the kit

Weight Breakdown
Fuselage 3.84 grams  
Stab 1.2 grams uncovered – 1.56 grams covered
Vertical Fin .65 gram uncovered - .74 gram covered
Wing 4.73 grams uncovered – 6.71 grams covered
Wing Mount  1.04 grams
Propeller 4.66 grams

Total Weight Without Rubber 18.96 grams

Another similar airplane I had built many years ago was the Air Hare which was a model class project for a couple of students, proportions were very similar and so are the flight characteristics. It is too bad the Air Hare kit is no longer available as that was a laser-cut kit. Both airplanes have fairly long fuselages which I think contributes to the pitch stability.

Air Hare on Left AMA Maxi Jr Right

Last evening was the first flights for the AMA Maxi Jr and it flew absolutely perfect from the first flight with absolutely no trim adjustments needed at all. Power is a single loop of 3/16” Super Sport Tan rubber which appears to be adequate power for a steady climb.  Unlike many smaller sport rubber models when the rubber runs out it glides fairly well and doesn’t go into a spiral dive.

From what I have heard from other people, everyone has thought this simple plane flies amazingly well.

Bill Kuhl

Video of First Flight

Tuesday, March 3, 2015

Upgrading to Spektrum DX9 Transmitter

In writing this article I am trying to give those people not familiar with the advanced technology available in model radio control systems a simplistic view of what is available to the hobbyist.  I have been in the process of moving all of my airplanes from equipment on 72 mhz to 2.4 ghz spread spectrum equipment. My decision to choose Spektrum brand equipment was mainly based on what the local hobby shop was selling. For the most part it has worked well for me. The first transmitter I purchased was the DX6i that was limited to 10 model memory and developed a problem with the elevator trim switch. Another factor in choosing Spektrum brand was it has worked easily with the Bind-n-fly models I have purchased.

DX9 Works Great With my Bind-n-Fly Airplanes

I Struggled to Get All Wing Functions Working on Sailplane

Just over a year ago I decided I wanted to invest in a better transmitter for more advanced model sailplanes I might be flying. The voice capability of the DX9 sounded not only cool but practical to alert the pilot to the position of a particular toggle switch. It would also interface with telemetry which is something I wish to try in the future. I was hoping that programming the DX9 would be easier than the DX6i but it has me struggling on certain issues. In my opinion the manuals need to go into more detail with good examples.

Files to be Updated Downloaded to SD Card

SD Card Placed back in Transmitter

 With my new transmitter I should be able to fly all the airplanes I would ever want to with 250 model memory, right now I am up to 15. The DX9 uses a SD card to save information to for not only the models but the programming code and sound used with the transmitter. To update you logon to Spektrum website and download files to SD card and then replace the card into the transmitter and do an update process.  I just went through the process because I was somewhat behind in the update releases. From reading the update description there were a fair amount of bug fixes and enhancements.  The sound files update takes a few minutes, the code file goes fast.

Loading Firmware Code into Transmitter

It has been a little expensive buying so many receivers to replace the 72 mhz receivers but I had gotten myself into a situation where I had transmitters from several brands, and extra transmitter modules for different frequencies.  The rechargeable batteries in those old transmitters were having to be replaced so staying with the old equipment would be just as expensive.  Now every plane I fly has the advanced features of this deluxe transmitter available.

Bill Kuhl

Additional Resources

Spektrum Website 

Radio Carbon Art Video on 2.4 Radio Technology