So I know I've covered gas/glow to electric conversions before on these pages but I've got a new one that I am going to let out of the bag. and cover it here for those who really want something a little more complicated. -- a twin engine aircraft.
Now, there's nothing really much of a mystery about this process other than the fact that you are doing everything twice. I also realize that there may be a few things that are unique to this particular project that may be insightful for some folks. Each post will have steps associated with it in the order that I perform them. The subject we are dealing with here is a Hangar 9 B-25 which has been out of production for 13 years and this particular model is 15 years old now. Previously flown on Evolution 36 engines the model came to me with those engines, a full suite of servos (9 I think), an old Futaba receiver I cannot seem to even give away, and a receiver battery that was about as dead as you can get. With all that context, let's get onto the process.
Step 1:
With the model having engines installed I opted to try and get them running again so that I could sell them to offset the cost of the project. $100 for both engines goes a long way here. I removed the props and cowls and soaked the carbs in nitro fuel overnight and they were still stuck but a hit with automotive carb and throttle body cleaner freed one while the other required a bit more persuasion. Eventually free, I reinstalled the props and put fuel in each tank and primed the lines per usual procedures and they both fired right up. What was surprising was that they both were well-synced up too.
Step 2:
I found a buyer pretty quickly for the engines which meant I could proceed with removing the engines. This is a simple process of removing one screw or bolt at a time. I removed the fuel tanks as well as the throttle servos. The tank removal required that I break away a piece of balsa holding them in position as part of the original installation. For this model I did have to remove the nacelles from the wing but that's two simple bolts.
Step 3:
Clean. Then, clean something. Then, clean some more. Even though this model was not put away "wet" per se, the model still had a film of oil from the glow fuel and then sat for a long long time and accumulated dust on top of that oily base. Combine this with the stink of cigarette smoke and you have yourself quite the cleaning project. Along the edge of the nacelle here you can see the line between the clean nacelle and the dirty wing. Then look at the solvent spray onto the wing and how the solvent is just melting away the grime. I'm using paper towels and Simple Green but really any good degreaser will work here. Kitchen degreasers like 409 work well too. Even after the initial cleaning I went back and did it all a second time with the degreaser again, and then a final wipe down with a cotton cloth and windex. Then I let the whole thing air out and bake in the sun to help remove the smoky smell. The more sunlight you get the more this will go away. Short of putting the model in a bag with an ozone machine, there's really no good way to remove smoke smell. Fly it more and the smell will eventually go away.
Step 4:
The blind nuts in the firewalls were removed by screwing a bolt back into them and tapping the bolt with a hammer until free. The remaining holes were plugged with oak dowel from the hardware store. This model uses a ply back plate behind a fiberglass nacelle but this same technique applies universally. I did have to drill out the holes to accommodate the larger diameter of the dowels but you kind of want that for a nice and snug fit. I then tapped each dowel flush with the firewall and soaked each one with thin CA until it pooled on the surface. It's a lot so I recommend a fresh bottle if yours is low. Some folks swear by epoxy for this job but CA has always worked well for me. The idea here is to plug the holes to maintain structure but also provide material that you may need to drill into again for new holes for your motor mount.
I'll note that I did this step along with the cleaning so note the cleaning marks for entertainment purposes for how dirty this model was.
Step 5:
The last part I'll post here is sourcing replacement parts. Sometimes you are lucky and sometimes you are not. In my case, I'm both. New cowls are just not available. The ones I have can fly the model fine but they have a large hole for the head and muffler to protrude as well as holes for the adjustment needle and fuel filler. The Front greenhouse plastic is pretty beat up and the other plastics are not in the greatest of shape but are fairly serviceable. A quick hop over to Park Flyer Plastics gives me a COMPLETE set of BRAND NEW vacuum formed plastic parts for $17. Shut up, and take my money. New parts all around will keep the look consistent rather than replacing just one part and the UV damage over time is a real thing on old models.
Now, there's nothing really much of a mystery about this process other than the fact that you are doing everything twice. I also realize that there may be a few things that are unique to this particular project that may be insightful for some folks. Each post will have steps associated with it in the order that I perform them. The subject we are dealing with here is a Hangar 9 B-25 which has been out of production for 13 years and this particular model is 15 years old now. Previously flown on Evolution 36 engines the model came to me with those engines, a full suite of servos (9 I think), an old Futaba receiver I cannot seem to even give away, and a receiver battery that was about as dead as you can get. With all that context, let's get onto the process.
Step 1:
With the model having engines installed I opted to try and get them running again so that I could sell them to offset the cost of the project. $100 for both engines goes a long way here. I removed the props and cowls and soaked the carbs in nitro fuel overnight and they were still stuck but a hit with automotive carb and throttle body cleaner freed one while the other required a bit more persuasion. Eventually free, I reinstalled the props and put fuel in each tank and primed the lines per usual procedures and they both fired right up. What was surprising was that they both were well-synced up too.
Step 2:
I found a buyer pretty quickly for the engines which meant I could proceed with removing the engines. This is a simple process of removing one screw or bolt at a time. I removed the fuel tanks as well as the throttle servos. The tank removal required that I break away a piece of balsa holding them in position as part of the original installation. For this model I did have to remove the nacelles from the wing but that's two simple bolts.
Step 3:
Clean. Then, clean something. Then, clean some more. Even though this model was not put away "wet" per se, the model still had a film of oil from the glow fuel and then sat for a long long time and accumulated dust on top of that oily base. Combine this with the stink of cigarette smoke and you have yourself quite the cleaning project. Along the edge of the nacelle here you can see the line between the clean nacelle and the dirty wing. Then look at the solvent spray onto the wing and how the solvent is just melting away the grime. I'm using paper towels and Simple Green but really any good degreaser will work here. Kitchen degreasers like 409 work well too. Even after the initial cleaning I went back and did it all a second time with the degreaser again, and then a final wipe down with a cotton cloth and windex. Then I let the whole thing air out and bake in the sun to help remove the smoky smell. The more sunlight you get the more this will go away. Short of putting the model in a bag with an ozone machine, there's really no good way to remove smoke smell. Fly it more and the smell will eventually go away.
Step 4:
The blind nuts in the firewalls were removed by screwing a bolt back into them and tapping the bolt with a hammer until free. The remaining holes were plugged with oak dowel from the hardware store. This model uses a ply back plate behind a fiberglass nacelle but this same technique applies universally. I did have to drill out the holes to accommodate the larger diameter of the dowels but you kind of want that for a nice and snug fit. I then tapped each dowel flush with the firewall and soaked each one with thin CA until it pooled on the surface. It's a lot so I recommend a fresh bottle if yours is low. Some folks swear by epoxy for this job but CA has always worked well for me. The idea here is to plug the holes to maintain structure but also provide material that you may need to drill into again for new holes for your motor mount.
I'll note that I did this step along with the cleaning so note the cleaning marks for entertainment purposes for how dirty this model was.
Step 5:
The last part I'll post here is sourcing replacement parts. Sometimes you are lucky and sometimes you are not. In my case, I'm both. New cowls are just not available. The ones I have can fly the model fine but they have a large hole for the head and muffler to protrude as well as holes for the adjustment needle and fuel filler. The Front greenhouse plastic is pretty beat up and the other plastics are not in the greatest of shape but are fairly serviceable. A quick hop over to Park Flyer Plastics gives me a COMPLETE set of BRAND NEW vacuum formed plastic parts for $17. Shut up, and take my money. New parts all around will keep the look consistent rather than replacing just one part and the UV damage over time is a real thing on old models.
6 years of flying the snot out of that airplane. While my current iteration of that airplane has a more scale 3-blade prop the approach is the same. More on power system selection later, which can be a highly debated topic. Again, this is my approach, not THE approach.
