1.
1/48
Monogram A-1H SkyraiderMotorizing Prop Aircraft
By: Len Roberto
As long as there have been models of prop-driven aircraft, brave souls have tried to portray their models in flight. Many methods exist and some adventurous products have come to market like Prop-Blur to give us even more options. The best and most realistic option remains a motor spinning your scale props. I have been experimenting with a bunch of models and wanted to pass on what I learned. It really is not that difficult and is also very inexpensive.
MATERIALS NEEDED:
I buy all of my materials from a company on the web call All Electronics (www.allelectronics.com) You need:
-DC motors (range from $1.00 to $3.75 for the biggest- most of what I used are $1.15 each)
-conducting wire (sold by the foot- but any copper wire will do- you know you have some! Make sure it is insulated)
-battery box (in single to 4 capacity for AA batteries- I use the double because it has leads already attached- $0.70 cents each)
-switch (standard toggle on/ off switch- $1.00 or so each)
-brass or aluminum tube to use as a stand and run the wiring down to the base
-wood or other base (any craft store sells pre-routed wood bases- $2.00 to $8.00)
-tubing to extend the motor shaft (brass or aluminum again to extend the shaft through the scale plastic engine
-risers (again the craft store sells intricate designs for woodcrafters- you just need some method of raising the wood base to allow room for the battery case and switch underneath)
SCALE:
So far I have only done 1/48 and 1/32 scale. They do make 2 miniature motors used to vibrate your cell phones. These mini motors are $1.25 each but they come with a weight on the shaft. They are quite fragile and so far- I have not been able to get the weights off without bending the shaft or breaking the motor. It is possible though. My inspiration for this new phase was seeing Paul Boyer’s article in FSM where he uses one of these mini motors to power a 1/72 Scale Spitfire. So it can be done but for mine- I went with one of the larger motors that are perfectly round and will fit into most 1/48 scale radial engine cowlings. 1/32 scale works as well but you will have to find a way to support the engine inside the bigger cowlings.
MODELS:
1.
1/48
Monogram A-1H Skyraider
For my first attempt, I wanted to pick a model with plenty of room inside the cowling and model. I can’t think of a better model than the Skyraider. You have a big round cowling requiring little support inside and you don’t even need to worry about extending the shaft through an engine because you can CA glue the motor right behind the inner cooling flaps. Using old sprue or strip stock, create some beams inside to give the motor more support. Once it’s closed up, you can’t go back in and make repairs!
You have to carve out room for the motor at the front of the fuselage. Use your Dremel and do a little at a time. Test fit over and over until you get a snug fit. This also provides extra support. Next you drill a hole in the belly big enough to fit your support shaft. Run your wiring from the engine down through the shaft then glue your wing onto the fuselage. CA glue the prop onto the shaft.
This is a great model to start with. Get creative! I did mine on takeoff with wheels almost in the gear bays. (Editor's note. Might want to get an engine for this kit as those flaps on the front were blown in by the wind from the prop blade, exposing the engine to cooling air. The Navy and later the USAF often removed them to make maintenance easier though many warbird owners put them back on when restoring their aircraft. Check your references.)
2. 1/48 Otaki F4U-1D Corsair and 3. 1/48 Tamiya F4U-1A Corsair
THESE WERE GIVEN AS GIFTS BEFORE I COULD TAKE PICS!
These required a bit more work. The main reason is that to retain at least 1 row of plastic cylinders, you need to find a way to extend the motor’s shaft through the engine with enough room left to attach the prop. I tried many ways of doing this but the best way is to find tubing just wider than the motor’s shaft diameter, cut it, and slip it over the shaft with CA glue. You may now have to drill out the plastic engine a bit more now to allow the extender to turn freely inside the plastic. Some grease may also be needed.
Take care
to keep the extender tube straight and to align the motor throug
h the plastic
engine. If it is off center- the motor will have trouble turning or it will
wobble noticeably. There is less room in here than the Skyraider so you may
have to sacrifice the lower cockpit to make room for the back of the motor.
4. 1/32 Revell F4U-1D Corsair
I picked up this kit at a show for a few bucks and immediately wanted to spin that big prop! I bought a slightly more powerful motor for this one. There is plenty of room in here! I was able to keep the first row of cylinders and CA glue the motor to the back of the plastic cylinders. I did need to glue some strips into the cowling to make the engine have a tight fit into the cowling. By hollowing out the front of the fuselage, the back of the motor had a round and supportive brace requiring no other bits to reinforce it. No other problems needed to be overcome and this motor makes a nice sound and spins at a high rate of speed!
5.
1/48
Monogram B-17G Flying Fortress
My uncle drew me a wiring diagram for this one- if anyone wants it just email me! I’ll get into wiring tips later. The 4 cowlings give you plenty of room but once again you face the issue of extending the shafts through the plastic engine faces. Dremeling out the inner cowlings allow you to CA glue the motors securely. I still put in a brace of sprue behind each motor for support and sturdiness. You need to assemble each wing then attach to each fuselage half. Then run your wiring though each half and out of the hole you made just aft of the bomb bay for the support shaft. I decided to not worry about clear parts and to black them out so no interior stuff was included. Now that I know what needs to be done- the next one will have more time spent on the model and it’s interior and crew! It sounds neat with 4 motors wailing away and the whole shakes and vibrates like the real McCoy!
6.
1/48
Monogram B-26B Marauder
Another
Monogram classic well suited for motorizing- the motors were CA glued to
the backs of the engines and just a little cutting was
required for a snug fit. Again there is plenty of room inside
for wiring,
just remember
to cut away holes to thread the wires through the
wings and bulkheads and then down through the support hole aft of the bomb bay.
NOTES ON SWITCHES, WIRING, AND OTHER STUFF:
1.
Here
is an easy way to remember how to rig the switch and battery box.
*Red wire from motor to red wire from battery box.
* Striped wire from motor and striped wire from battery box to the leads on the switch.
If the Prop spins the wrong way, just reverse the wires (stripe to stripe then red to the switch- or swap at switch) I use CA or Elmer’s glue to attach the switch to the base. The battery boxes have screw holes.
2. Keep testing that the motor works along the way – especially before you close everything up!
3. When using CA glue anywhere near that motor- do not get any inside the motor or on the shaft- unless you are gluing the prop to the shaft- but be really careful to not get any down the shaft which will seize the motor.
4. Sometimes you may have to drill out the mounting hole for the prop to fit onto the new extender shaft.
5. When attaching the prop, try to get it as balanced as possible. There is probably a good way to measure this but I just use the old eyeballs.
6. If your battery box gets hot- you wired something wrong and it will melt the box and cause a problem….
7. Try to find the center of balance when placing your support shaft. The motors will change where you think it should be but you don’t want to have a situation where the plastic around the shaft in the model’s belly will crack or bend over time.
8. One last warning- make sure it all works and spins before you close up the airplane! If that works, then the other steps like switches and wiring will work out and if there is a problem, at least you know it is not inside.
Have fun and experiment! It really makes you model come alive! Any questions I’d be happy to help.
-Len Roberto