Workshop

August 15, 2009

The issues were all resolved as far as they could be without assembling the plane. we added the interior of the plane and moved it to my garage for final assembly and engine test.

The assembly began with the rudder and the stab. They all fit into the fuse with interlocking tabs and they were in good position with all the surfaces straight and secure. There are 2 bolts that go through the back of the stab spar, pass through the downward tab from the rudder and enter a blind nut imbedded in the back of the stab spar. These were fine looking bolts and they were at least 1/4" short of the blind nuts. This is another engineering fault and the bolts are metric and must be replaced with longer ones.

The tail cone was installed and the back was done.

The wings went on without incident and the ailerons needed linkage adjustment to work properly as the servo tester did not center the servo arms the way the receiver did. This was resolved and the throw was set according to the instructions The struts were bolted on and the plane checked for flatness and it looked just fine.

There are landing and navigation lights and we checked them for operation. Some changes will be made in the lighting system at a later date as they are not bright enough.

The nose gear was adjusted to lower the nose some and get a better angle on the wings. The nose wheel and rudder were tuned to get the throw and get them both to center on the transmitter. This was done with linkage and ATV adjustments.

The flaps were not operating correctly and after adjusting the hardware, I strongly suspet the servo was bad on one side. George will replace the servo and all should be just fine.

The motor test was next and I fueled it up and all looked just fine. I had checked and there was power to the ignition computer and there was good compression in the engine. Since these are the three things needed to run a motor, we were feeling good about the test. The motor did not start and we figured out that the throttle linkage was set for wide open and completely closed on the carb. The low throttle was closed too tight and the engine could not get the needed air to fire up. I opened the throttle to about 1/2 and the carb opened up enough to take off. By adjusting the ATV we were able to make the linkage stop at a fine idle. The high speed needle needed some adjustment and the motor ran fine. The big DA took oth of us to hold it back at full throttle.

The plane was taken apart and loaded in the trailer. There are some issues left that George will resolve in the days ahead and it will soon take to the air.

 

 

August 14, 2009

The day began with the final work on the rudder servo.

as you can see above, the servo was mounted and the groove cut so that the arm could operate the surface without rubbing. the installation is shown below and with a little white paint on the linkage it will all look very nice.

The rudder was then glued in and the hinges adjusted so that it would operate properly.

 

The grip block on the elevators was machined so that it had a wider groove that would allow it to clamp on the elevator shafts. The elevators were aligned and clamped in position and the linkage set to approximately the right length. Once this was done I glued the elevator hinges in place and allowed it to dry.

The wiring was the next thing to do since the surfaces were all set to go on the plane. The rear half of the fuse was installed and checked for position and tightness. The front of the plane was mostly wired and the wires were passed to the passenger compartment for final wiring to the receiver. The ignition digital switch was wired to the ly-po battery and secured to the motor box. A set of wires were run to the passenger compartment to be plugged into the receiver and a charge line for the battery was run so that George can charge the ignition battery from the same position as the two main batteries.

The wires were soldered that would go from the rudder and elevator to the receiver. These were run to the passenger compartment and taped to the bottom of the rear fuse. The aileron and flap wires were then run from the wing roots to the floor of the passenger compartment. These were run under the molding and we thought we were working on a car.

Once all the lines were run and plugs on the outer ends, I made the connections to the nine leads for the receiver. The flaps needed a reverser and that was wired in to the circuit as the connections were made up. This took a lot of time to get right and our reward was that all the flight circuits worked on the first try and the ignition switch had an indicator bulb plugged in backwards which was resolved in short order.

the main batteries were packaged and vlecored to the structure under the floor boards and the switches were installed under the back seats and wired to test their operation.

The lights were all installed and we test plugged them as well.

As the day ended, we had the plane ready to set the interior and do the first assembly. Linkages will then be adjusted and the radio program adjusted to its final state. The prop and spinner will go on and the engine test will be done. The CG will be checked and the lateral balance done to be sure there is not a heavy wing. This will ready the plane for the first flight.

 

August 13, 2009

The second wing had servos, linkage and ailerons installed and checked. There will be further adjustment of the linkages once the plane is assembled and the system is on the receiver. There is always a little variation between the servo tester and the real system. The ailerons have Hitec 5645mg servos and the flaps have hitec 7955tg because the flaps seem to need more power. The linkages supplied were all used after some adjustments. The ball joints were replaced with hanger nine equipment just because we have a lot of experience with them and the plane is hard to get home if the links start to fail. Everything was locktited as we built.

On to the elevators and they were constructed with the hardware supplied. One end of the linkage was a ball joint with a #2 screw holding it to the horn and the other end was a kwick clip. This just did not seem heavy enough for a plane this size so I converted both ends to a 4-40 ball link and secured them with double nuts and locktite.

The elevators are connected with an aluminum rod that has a grip block in the center. The grip block did not prevent slippage and the elevators were easy to move in the block after it was secured. The system did not supply enough mechanical clamping force on the shaft. I disassembled the block and shafts and found the ID of the hole in the block was equal to the OD of the shaft. This will never work as the block is machined incorrectly. Having the elevators loose in fight might be objectionable so I set about making it work.

The rudder needed the same treatment as the other surfaces. The servo was mounted on the bracket with 4-40 bolts and nuts and an extended arm was bolted on the servo. The hole was plotted and cut in the hatch and the servo bracket was then mounted on the hatch with the provided bolts and nuts. the linkage provided would not work so I replaced it with a hanger 9 titanium link that was 2.5" long. the rudder has a 5645mg servo on it as others have found that to be enough power.

August 12, 2009

The choke servo was mounted and tested. It was located just aft of the throttle servo and was spaced off of the motor box to allow the linkage to reach the choke lever. The choke control horn was short and was out of position. I bolted a metal servo control arm on the linkage and then set a ball like to ensure there would be no binding later.

The gas tank was then plumed and set in place inside the motor box with foam padding on all sides. The tank was leak tested before and after installation. Velcor was used to secure the tank to the frame.

Next the fuse was separated from the aft section and the front section stood up on a pad so that I could work on the motor mount area. I set the mounted motor and motor box on the fire wall and positioned it on the marks I had drawn to indicate the motor box would be centered on the fire wall. The cowl was then set and the motor positioned so that the spinner would line up with the cowl front. Marks were made where the bolts would be and the motor removed to the bench. The holes were drilled and blind nuts were assembled to be installed behind the fire wall.

The bolts and blind nuts were installed and the glue allowed to dry. The motor mount was then placed on the firewall and I noticed that the firewall was not flat and the motor box rocked instead of sitting flat. This problem was solved with shims between the firewall and the motor box. With a few fittings, the spinner lined up and the motor was mounted in its final position.

Next the steering servo was hooked up to the nose gear and tested. The wires for all 3 servos were then extended by soldering on heavy gauge wire that would reach to the passenger compartment.

The wheels and wheel pants were assembled without incident and the front of the fuse was put in its feet.

The shot above shows the aileron servo hatch and I got the servo in place and used the supplied metal links with added ball joints to be sure there will be no binding.

The flaps are scale in that they are drop hinged and the hardware was in the wing as it arrived in the shop. I mounted the servo after extending the wires and hooked up the links. The servo tester confirmed that the flaps worked well.

The robart hinges were then glued in place and one wing was complete.

 

The elevator was assembled and the servo mounted. Since the tail section is removable, the rudder and elevator servo will have plugs in the wiring.

As the day ended, the parts are progressing well and we plan to assemble and begin testing the plane during the next session on Friday.

August 11, 2009

The plane was brought to the shop and the fuse was wheeled in with several boxes of parts and pieces. The first thing to do was figure out the engine mounting system and get all of the associated equipment mounted to the front end

The first task was to build the motor box. It is made from heavy gauge aluminum. The motor box was constructed and it was clear that there had been changes made to the structure. The firewall was checked for alignment and it had 2.3 degrees of right thrust and 4.4 degrees of down thrust relative to the firewall. It is key that the cowl line up with the back of the spinner and after measuring we found large differences between the motor box and the front of the cowl.

The normal construction of a full size plane would call for no thrust changes and therefore I was checking to see the fit to the cowl. By using the work bench as the firewall, we were able to see what the sinner to cowl joint would look like.

I positioned the motor on the motor box and then put the cowl in place resting on the work bench just as it will on the firewall. The thrust built into the motor box was not cast into the cowl and so the spinner was crooked compared to the cowl. After consideration of the problem and discussions with others that have flown the plane, we decided the thrust built into the motor box was an engineering change made by the manufacturer and they did not change the cowl. So, we are between the rock and a hard place and something had to give or the plane will have a silly looking front end.

We used shims under the motor to correct the spinner joint and ended up with 2.8 degrees of down thrust and .3 degrees of right thrust. All these measurements were done with a digital level and they were relative to the bench ( which is the firewall). The motor was then mounted to the motor box and we began adding the equipment needed.

The mufflers were then mounted to the DA 150 and we noted that the pipes will need to be shortened to clear the cowl.

The throttle servo was mounted to the bottom of the motor box and the linkage was set up so that everything worked. Great care must be taken with this setup because it is all mounted on metal with titanium links. When the servo is first powered up, it must not go to the limit or something will be destroyed. I will set the ATV in the transmitter at + and - 30% and then adjust to the limit of the throttle.