Monday, October 22, 2018

Dewey Bird Control Line Adventures 2018

My first real start in model aviation was with ½ A control line planes, I remember building a Carl Goldberg Stuntman 23 when I was 9 years old. Last year in the fall I was trying to fly an electric control line for the first time after no control line flying for many years. I was running out of warm weather and tried to fly in too much wind with too long of lines. The plane was repaired and flown successfully but it looked like this plane was rather fragile to be crashing from beginner mistakes, so over the winter I built a Sig ½ A Dewey Bird to be powered with a Cox Babe Bee .049. 

1/2 A Dewey Bird

Bottom of Piston shows Where Connecting Rod Came Apart

The Cox Babe Bee is another story, I saw it on a hobby shop counter. The owner said it didn't run and that I could have it. It felt like something was broken, it turned out the connecting rod had ripped out of where it connects to the piston. I thought maybe it had over heated as it had a 7-6 wood propeller on it but people tell me larger propellers are run on .049's for Texaco event. I found a piston in my junk parts collection and the engine ran great.

Dewey Bird in Stooge

Electric Control Line

Free flight kept me really busy for most of the summer but after the Nats I fly my Dewey Bird for first time. There was no one to help so I made a stooge using a couple pieces of wood in a drillpress vise. I was using 35' .012 metal lines which I had from childhood. I think 26' lines are recommended, it flew on the long lines but tension was not great. Next time out I flew the Dewey Bird on 26 foot Spider wire lines which were better but it was really gusty that day. It was a good lesson in keeping the line tight when a gust hit it. For the next time flying, I added sidethrust and moved leadouts back. It might have helped a little. Again I tried to loop and stepped backwards really quick to try to regain tension. I tripped in the tall grass and fell on my butt. One more try and the plane went around once but lost tension and went up for another loop but crashed on the bottom. Only broke the propeller but I fell again.

Damage from Slack Lines

 Next time out I tried loops twice and crashed but no damage. Then I leaned the motor out more, I was afraid it would get too lean in the air but it didn't. Now tension was better, I tried a loop and it went around easy with plenty of room to spare. Tried it again and it went around fine. Fly more laps and then decided to try one more time but hesitated and the plane went into the wind and there was slack in the lines. The crash did damage this time, it only took a few minutes to fix when I got home.  

Add Weight to Tail  to Move CG Back

Now it gets dark so early and it has been windy for a couple of weeks. One evening I flew my electric control line again and it flew well.  Then tension is much better with this plane but I still want to get more practice with the ½ A.  I still have a Carl Goldberg Buster with a Fox .35 on it from my childhood I want to fly that again also. 

Goldberg Buster

I realize it would no doubt be easier to learn aerobatic maneuvers with a larger plane; at this point I am just too afraid of crashing a larger plane. There is also the challenge of pushing for higher performance with a small plane. 

Bill Kuhl

Wednesday, October 17, 2018

Experiments with STRIX Free Flight Electric Motor Timer

In the past few weeks I have been experimenting with using a small electric motor timer that I purchased from the RMRC company for under $7. An online friend had sent me a link to this and I ordered a couple of the timers. After receiving the timer I discovered it used the larger JST 2.0 plug in connecting to the battery, so another order was placed for a couple of batteries and a charger that fits this connector. The connector is slightly larger than the connector used on the Eflite planes I have.  In the future I want to replace the connector on the timer with the more standard connector on a sample timer. This would make it possible to use batteries and chargers that many people already have.

Electric Powered Guillow's Cloud Buster

STRIX Timer, motor, and battery
My first test aircraft was an injected foam glider the Guillow’s Skyraider, the motor was mounted on a pylon I constructed out of balsa, everything held together with low temperature hot glue.  The total weight was 56 grams which is too heavy for much of a climb. For a propeller I used one from an Aero Ace biplane I had, it did not overheat the motor like when trying an E20 size propeller. The specifications of the timer call for 6 mm or 7 mm motor, I used 7 mm motors from RMRC which come for in packages of four motors, two wired for clockwise and two counter-clockwise. 

Robbed the Propellers

Comparison of Plug Sizes

Charging Board and AC Power Supply, can use Lipo Battery 3S or 4S

The foam glider might be great if it were lighter, the first flights it only got maybe 20 feet high. I removed some foam from the glider and it started climbing higher. The stability was just okay, it tended to wander around in the sky but it always survived a hard landing.

Electric Foam Glider

For the next plane I wanted to try a balsa plane with a really simple structure, I found a Super Dart in my basement which is similar to Sig Thermal Dart, flat pointy wings. A real short test fight with timer a battery taped on showed that this will climb better with a total weight of 23 grams. The weather has turned windy all the time which is bad for test flying. After another flight in the wind the second flight resulted in the fuselage breaking in multiple places. In the future would like to try this with a basswood fuselage as I would like to find really simple planes for the electric setup.

Super Dart Crash Damage

As I see this timer/motor setup, it would be good for kids flying in a schoolyard, the maximum run is only 10 seconds. You can select between 5,8, or 10 seconds very easily. With the battery that I found to fit the connector  at 220 mah it will give many flights on a single charge. The battery is rather heavy at 6 grams, timer 3 grams, and motor at 3 grams. The increased weight over a rubber motor would explain why crashes on models designed for rubber power would be more damaging. 

Cloud Buster Electric

The last model I have tried was a Guillow’s Cloud Buster built a long time ago. I think this model will work well but again I tried to fly it in way too much wind. First short flight it went too much right but recovered. I added too much weight on left wingtip to correct on second flight and it hit the ground in a left spiral dive breaking the pylon. I started building a new pylon that I can mount the timer and battery inside and have the wing held on by rubber bands. This type of model I have to believe should climb high enough to glide around for an additional 30 seconds or more. Kids do not even have to wind the rubber which should not be a big deal but I find some have trouble. I am looking for other sources of motors and propellers at an inexpensive price. I will write another article as I progress with this farther.

Crash in Progress

Rebuilding Pylon
Update 10/18/2018

It was relatively calm this morning as the sun was coming up but there was frost in the grass. I was determined to get in more test flights on the Cloud Buster I rebuilt the pylon for with the wing now held by a rubber band before work.  First flight at 5 seconds looked alright so went to 8 seconds. The plane had too much right turn, adding clay to wingtip had it going straight with a series of small stalls, taking a small amount off it was better but it seemed to easily circle either direction.  The plane climbs but not very steep, I think more wing area might help. Someone suggested the AMA Maxi Jr might work which I have and will probably try, it has a constant chord wing. The Cloud Buster tapers to thin at the tips.  If I used a lighter battery I think that would help too.

Cloud Buster with New Pylon

12/11/2018 - Sig Cub Electric

Bill Kuhl

Related Links  Link to Timer  
Foam Guillow's Glider   Guillow’s Cloud Buster

Monday, October 8, 2018

Last 2018 Free Flight Contest Minnesota

I was so close to not attending the last 2018 outdoor free flight contest in Minnesota because of the wind prediction and threat of rain. It was cool, dark, and windy at times but the direction gave a good deal of room to drift without getting into trees or corn. For me it was one small problem after another but I still had a great time. At least I should have more time now to get my equipment better prepared for next year.

First Wilbur Flight was high enough for prop to fold

To start flying I decided to take out my Wilbur rubber model that normally flies great but has had issues at the last two contests. Two months ago the center of the wing folded on launch and last contest it would barely climb. The blades were loose on the hub which I repaired and it climbed better in test flight but I did not get up to full winds. At this contest the counter on my winder came loose and the screw was stripped out so I had to count winds and with weird gear ratio that isn’t easy. First test flight it did better than when the blades were loose but after that it just got worse.

Bearing that is Dragging

When I picked up the model with turns left the propeller would barely turn over. The metal sleeve that goes into noseblock hole was loose because it was trying to turn in the balsa. Someone squirted some fuel into the ball bearing thrust bearing that appeared to be dragging. After I glued the sleeve I tried a couple more flights and result was the same. When I got home I looked closer at the ball bearing and it seemed like the two sides of the bearing could be wiggled apart farther than the same type of bearing in another airplane. At times it appeared to turn real hard but not all the time. Replacing the bearing would not be easy as the propeller shaft would have to be broken loose in front where it attaches to the hub.

P30 Still on the Field

For the P30 event I brought my older NJAPF p30 along because I didn’t want to risk my Polecat X in the wind. The fuselage really needs a recovering but the DT line broke just as I tried to wrap it around the rear peg. I didn’t have any line along so I bypassed the DT and hoped for the best. I did not wind it too much because I did not have a counter but I did have a torque meter for P30. Problem was I was not sure what torque would break the rubber. At least I got in 3 official flights and did not lose the model.

No DT Sunday P30

There was another guy flying P30 that did not use a DT because he thought the popoff wing line was causing a trim problem. He made a joke about it being “no DT Sunday” and needing to build a new model. I timed his flight and the model really climbed high, it must have been in enough lift to maintain although it wasn’t climbing any higher. After 2 ½ minutes I lost sight of it but he was able to find the model without a tracker. 

1/2 A Streak Missed Puddle

I flew my ½ A Streak after that just for fun. It was a little harder getting the glow motor running at 50 degrees than when it is 80 degrees. The needle valve needed some adjusting but then it ran well and pulled the plane to a good height. Transition was good and the glide did not stall and was in a gentle right circle, just came down too fast.

My DLG changed trim from last time flying, thought I was getting it readjusted and then it crashed. Like every contest the time just went too fast, I leave rather early because it is a 3 hour drive home. Closing with more pictures from the contest.

Gary Oakin's Rubber Model

Dave Braun's Scale Model Did not Like the Wind

Bill Kuhl

Monday, October 1, 2018

Witch Hawk 500 Free Flight Story

 In the Fall of 2016 I purchased the Witch Hawk 500 kit from BMJR because I wanted to try a larger glow powered free flight, at that time my only glow powered free flight was Cox PeeWee .020 powered. For 2017 the Witch Hawk was to be the One Design Plane at 2017 Nats. I didn’t get mine built for 2017 Nats and barely finished for 2018 Nats. 

2018 Nats Before Picture

Building a larger kit went easier than a small one in that it is harder to break pieces during construction but I had new things to try with this project. I covered it with Polyspan which I had only done before on parts of models, it went pretty well other than trying to find the shiny side. The fuselage was covered with silkspan. I decided last winter I would like to try an airbrush so I ordered the components for a system; it needed some brass fittings for connections. Local auto supply store helped me with that. I sprayed it with the dye that Larry Davidson sells and that went well.  For this large of model, a larger airbrush might have been better but it worked.

Under Construction

Airbrush Compressor

For a larger glow model running on pressure I needed an electric starter attached to a stand, as I have a small car this had to be compact. I found a plastic stool that folded flat and attached my starter and connections to that. To turn it on and off I ordered a trolling motor foot switch.. This was the first time running pressure and I decided to use a Red Cap bladder for my K&B .19 engine with original needle valve. I ran it on a test stand first and it ran pretty well.

Starter Setup

Before the 2018 Nats I had just enough time for some test glides and to run the motor on the plane. At the Nats I picked the first really calm day to test fly. I was nervous, just sure something would go wrong. First short flight it went straight ahead; stalled and came down breaking the propeller. Added tiny bit of rudder trim, next flight went up and transitioned nice but with no wind it glided back into pit area and hit a golf cart. It broke the wing in half but worse than that broke the scroll off my Texas Timer Max IIIa timer.

First Short Flight

Flew Through Golf  Cart

Broken Timer

Broken Wing

Back closer to home I do not have very large flying fields to use so I made the decision to install RC for motor cutoff and RDT. Later I could install an electronic timer to control the servos. To cut the motor, Greg Stewart gave me the great idea to use a valve made for RC smoke systems, Dubro sold this but I had to order through eBay to find one. Fixing the wing was a fair amount of work but it looked pretty good even after spray paint.

RC Install
Recover After Repair

As the flying season is winding down I wanted to fly it again, Saturday morning was darn near calm but there was frost on the ground. I had a little trouble getting the motor running and when I did it was surging a little. I launched it anyway and it went straight ahead and climbed darn near straight up. If it looked like there was any sign it would crash I would cut the motor. It climbed fine so I cut it when it was getting fairly high, it stalled straight ahead but had plenty of altitude to recover and as it leveled out it went into a nice glide to the right and landed. 

Frost in the Grass

My hands were cold and I needed to be somewhere so I did not fly it again. I was really happy. I know people have told me larger free flights are easier than small ones but I know they can crash harder also.

Bill Kuhl