I was intrigued about converting the P-51D Mustang from its free-flight
configuration over to a light-weight indoor R/C model. The product specs are as
follows:
Wingspan 11 inches, Length 9.3 inches and an all up weight of 8 ounces.
This model has a small pager motor and an 80 mAh Nimh akku cell to provide power. Its size obviously dictates the use of micro r/c gear and a little fore thought for the conversion.
I have decided to use Plantraco gear for both power and radio control.
The P-51D is listed as product GEEF0400
Should this conversion be successful, I may try conversion on the rest of the fleet.
The first task was to determine how to crack open the P-51 without destroying the model in the process. The P-51 is assembled at the factory with a combination of CA and silicon glues. A #11 hobby blade is a little too thick and unwieldy for cutting the fuselage open. A single edge razor blade is probably worse.
I ended up making a wonderful “joint separator” from a disposable razor (3-blade) and a short length of yellow control rod tubing. After carefully separating the razor head and removing the blades, one end of each blade was snapped off at a 45 degree angle for ease of use. Once the blade was glued to the end of control rod tube, I now had a wonderful surgical instrument that has a blade less than 1/2 the thickness of a #11 blade. It is also nicely flexible for cutting between the wing and fuselage at the glue joint.
The first item removed from the model was the tail section. The cutting action of the disposable razor made clean work of this part of the operation.
Next the wing was separated fro the fuselage and then the fuselage was split open along the center seam. Once cracked open, I was pleasantly surprised with the amount of room within the fuselage cavity. Plenty of room here for radio gear and battery pack.
Probably the hardest part of this conversion is removing the existing motor, battery and associated hardware from the fuselage. Here I found that the battery, motor and charge plate are spot glued with CA and further held in place with generous amounts of white silicone glue. Patience here is very important to successfully removing the components. Prying and pulling gingerly while carefully slicing through the glue is key to successfully removing the components.
Once accomplished, the foam parts are relatively clean and the P-51 can now be treated as a kit ready for radio gear.
The radio gear I chose for this conversion is all available at Plantraco gens ace which are listed as the following:
Micro9 3-channel receiver 0.9 gram weight
2 MicroAct magnetic actuators 0.4 gram weight each
GB03 gear drive motor set
LP90 Bahoma Lipo cell
A 100×80 prop will be used with the power system.
Working with the empty fuselage halves, some of the foam was removed to make way for the new components to be installed. These foam areas were the raised sections that located the NiMH battery and some foam up front was removed that surrounded the original motor.
The foam removed up front was to make clearance for the GB03 motor/gearbox. I also made sure that a good down thrust and right trust angle would be achieved when the motor assembly was mounted. Images of this area will be posted later.
The first component I chose to install was the elevator magnetic actuator. A hole was cut in the fuselage half (with many minor adjustments to get it right) and the actuator was nested in the whole. With this actuator, there wasn’t a need to counter sink the unit deeper into the foam, just cutting the hole was enough to allow full operation of the actuator arm.
Prior to permanently mounting the actuator, it was removed in order to install the centering magnet on the outside of the actuator coil. You have to have really good eyes or a magnifying glass for this task. Don’t sneeze or cough when work with the tiny magnet either.
Once the actuator was permanently installed, a small section of double sided tape was installed to hold excess actuator lead wire secure to the fuselage.
The rudder actuator was installed in the other fuselage half. The location was slight more aft from the elevator actuator to prevent mechanical interference of the actuator arms when the fuselage halves are put back together.
The actuators were plugged into the receiver and checked for proper operation. Once the receiver is installed in the fuselage, it is very impractical to reverse the connection if the actuator is operating in the wrong direction.
To mount the receiver, I had to add 2 ABS stand-offs to the receiver PCB. These receivers are normally attached externally to flat foamy air frames, not internally within a full fuselage. Again, this was an operation requiring the use of a magnifying glass. The stand-offs are ~3mm in height, tack glued near the lead connectors on the edge of the PCB. The receiver was then carefully glued in place on the right fuselage half.
The third image in this post shows the amount of foam material removed to allow installation of the motor gear box assembly.
The fourth image is showing the internal layout of the radio components.
***Hind site has told me I should have mounted the receiver further forward than what is shown*** more on this later.
Once satisfied with the component installation, the fuselage halves were glued back together. I was very careful here not to use too much CA, probably only about 10 small “dots” of CA around the parameter of the fuselage. The wing was then glued back onto the wing saddle of the fuselage.
The belly pan section of the wing that contained the charge plate was removed for easy access to the receiver. This is required in order to install the battery pack for flight (Bahoma cells are attached to the receiver with magnets). The size of the access is a little unsightly but I felt necessary for ease of installing the battery pack.
Next was to tackle the flight control surfaces. The elevator halves were removed and trimmed to an operational size as well as the rudder. The elevators and rudder then had the hinging surfaces bevel to approximately 45 degrees using a sanding block.
To join the elevator halves, a length of 0.5mm carbon fiber rod was glued to the leading edge of the halves. The elevator assembly was test fit to the stab and a notch was then cut from the vertical stab to allow clearance of the carbon fiber rod.
The hinging operation was taken care of by using Blenderm tape. Four small pieces were used on each elevator half and three were used for the rudder.
Micro control horns need to be made at this point. You can use some of the plywood control horns available out there for this. Of course the smaller they are all the better. I did not have any of these in my stock of parts, but do have plenty of the control horns from different micro-warbird lines. I cut down 2 of the ABS control horns until I had two that were 5 mm long. One hole was drilled in each at the end then they were glued in place on the elevator assembly and the rudder.
The tail group was then test fit to the fuselage and checked that is was square with the wing. Once satisfied with the fit, the tail group was glued in place and allowed to cure prior to moving on to the final steps of this conversion.
Pushrods came next. I used 1 mm carbon rod cut to length. For the “Z-bend” and “Figure 4″ wire ends, I used straight pins with the heads and points cut off. The straight pins were bent to shape and then attached to the carbon rod ends using shrink tubing.
The “Z-bend” of the rod was inserted into the control horn and the “Figure 4″ end was attached to the actuator arm. Length adjustment was accomplished by re-heating the shrink tube and making the length adjustment before it cools back down.
Final checks were made with the radio equipment energized.
One final task was to check the CG of the P-51. I quickly assembled a balancing rig using a 6″ long balsa block and two bamboo skewers 6″ long. The balance point for this model is 20 mm measured from the leading edge of the wing next to the fuselage. It is easiest to check the balance with the plane inverted. Of course the battery pack must be installed when checking the balance.
Due to my poor choice of receiver location, I had to add some plasticine clay to the nose in order to achieve proper balance. As I had posted earlier, the receiver should have been mounted as far forward as possible.
Now the only task left is flight testing. I will report on this once this has been accomplished.
Wingspan 11 inches, Length 9.3 inches and an all up weight of 8 ounces.
This model has a small pager motor and an 80 mAh Nimh akku cell to provide power. Its size obviously dictates the use of micro r/c gear and a little fore thought for the conversion.
I have decided to use Plantraco gear for both power and radio control.
The P-51D is listed as product GEEF0400
Should this conversion be successful, I may try conversion on the rest of the fleet.
The first task was to determine how to crack open the P-51 without destroying the model in the process. The P-51 is assembled at the factory with a combination of CA and silicon glues. A #11 hobby blade is a little too thick and unwieldy for cutting the fuselage open. A single edge razor blade is probably worse.
I ended up making a wonderful “joint separator” from a disposable razor (3-blade) and a short length of yellow control rod tubing. After carefully separating the razor head and removing the blades, one end of each blade was snapped off at a 45 degree angle for ease of use. Once the blade was glued to the end of control rod tube, I now had a wonderful surgical instrument that has a blade less than 1/2 the thickness of a #11 blade. It is also nicely flexible for cutting between the wing and fuselage at the glue joint.
The first item removed from the model was the tail section. The cutting action of the disposable razor made clean work of this part of the operation.
Next the wing was separated fro the fuselage and then the fuselage was split open along the center seam. Once cracked open, I was pleasantly surprised with the amount of room within the fuselage cavity. Plenty of room here for radio gear and battery pack.
Probably the hardest part of this conversion is removing the existing motor, battery and associated hardware from the fuselage. Here I found that the battery, motor and charge plate are spot glued with CA and further held in place with generous amounts of white silicone glue. Patience here is very important to successfully removing the components. Prying and pulling gingerly while carefully slicing through the glue is key to successfully removing the components.
Once accomplished, the foam parts are relatively clean and the P-51 can now be treated as a kit ready for radio gear.
The radio gear I chose for this conversion is all available at Plantraco gens ace which are listed as the following:
Micro9 3-channel receiver 0.9 gram weight
2 MicroAct magnetic actuators 0.4 gram weight each
GB03 gear drive motor set
LP90 Bahoma Lipo cell
A 100×80 prop will be used with the power system.
Working with the empty fuselage halves, some of the foam was removed to make way for the new components to be installed. These foam areas were the raised sections that located the NiMH battery and some foam up front was removed that surrounded the original motor.
The foam removed up front was to make clearance for the GB03 motor/gearbox. I also made sure that a good down thrust and right trust angle would be achieved when the motor assembly was mounted. Images of this area will be posted later.
The first component I chose to install was the elevator magnetic actuator. A hole was cut in the fuselage half (with many minor adjustments to get it right) and the actuator was nested in the whole. With this actuator, there wasn’t a need to counter sink the unit deeper into the foam, just cutting the hole was enough to allow full operation of the actuator arm.
Prior to permanently mounting the actuator, it was removed in order to install the centering magnet on the outside of the actuator coil. You have to have really good eyes or a magnifying glass for this task. Don’t sneeze or cough when work with the tiny magnet either.
Once the actuator was permanently installed, a small section of double sided tape was installed to hold excess actuator lead wire secure to the fuselage.
The rudder actuator was installed in the other fuselage half. The location was slight more aft from the elevator actuator to prevent mechanical interference of the actuator arms when the fuselage halves are put back together.
The actuators were plugged into the receiver and checked for proper operation. Once the receiver is installed in the fuselage, it is very impractical to reverse the connection if the actuator is operating in the wrong direction.
To mount the receiver, I had to add 2 ABS stand-offs to the receiver PCB. These receivers are normally attached externally to flat foamy air frames, not internally within a full fuselage. Again, this was an operation requiring the use of a magnifying glass. The stand-offs are ~3mm in height, tack glued near the lead connectors on the edge of the PCB. The receiver was then carefully glued in place on the right fuselage half.
The third image in this post shows the amount of foam material removed to allow installation of the motor gear box assembly.
The fourth image is showing the internal layout of the radio components.
***Hind site has told me I should have mounted the receiver further forward than what is shown*** more on this later.
Once satisfied with the component installation, the fuselage halves were glued back together. I was very careful here not to use too much CA, probably only about 10 small “dots” of CA around the parameter of the fuselage. The wing was then glued back onto the wing saddle of the fuselage.
The belly pan section of the wing that contained the charge plate was removed for easy access to the receiver. This is required in order to install the battery pack for flight (Bahoma cells are attached to the receiver with magnets). The size of the access is a little unsightly but I felt necessary for ease of installing the battery pack.
Next was to tackle the flight control surfaces. The elevator halves were removed and trimmed to an operational size as well as the rudder. The elevators and rudder then had the hinging surfaces bevel to approximately 45 degrees using a sanding block.
To join the elevator halves, a length of 0.5mm carbon fiber rod was glued to the leading edge of the halves. The elevator assembly was test fit to the stab and a notch was then cut from the vertical stab to allow clearance of the carbon fiber rod.
The hinging operation was taken care of by using Blenderm tape. Four small pieces were used on each elevator half and three were used for the rudder.
Micro control horns need to be made at this point. You can use some of the plywood control horns available out there for this. Of course the smaller they are all the better. I did not have any of these in my stock of parts, but do have plenty of the control horns from different micro-warbird lines. I cut down 2 of the ABS control horns until I had two that were 5 mm long. One hole was drilled in each at the end then they were glued in place on the elevator assembly and the rudder.
The tail group was then test fit to the fuselage and checked that is was square with the wing. Once satisfied with the fit, the tail group was glued in place and allowed to cure prior to moving on to the final steps of this conversion.
Pushrods came next. I used 1 mm carbon rod cut to length. For the “Z-bend” and “Figure 4″ wire ends, I used straight pins with the heads and points cut off. The straight pins were bent to shape and then attached to the carbon rod ends using shrink tubing.
The “Z-bend” of the rod was inserted into the control horn and the “Figure 4″ end was attached to the actuator arm. Length adjustment was accomplished by re-heating the shrink tube and making the length adjustment before it cools back down.
Final checks were made with the radio equipment energized.
One final task was to check the CG of the P-51. I quickly assembled a balancing rig using a 6″ long balsa block and two bamboo skewers 6″ long. The balance point for this model is 20 mm measured from the leading edge of the wing next to the fuselage. It is easiest to check the balance with the plane inverted. Of course the battery pack must be installed when checking the balance.
Due to my poor choice of receiver location, I had to add some plasticine clay to the nose in order to achieve proper balance. As I had posted earlier, the receiver should have been mounted as far forward as possible.
Now the only task left is flight testing. I will report on this once this has been accomplished.
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