Advice Needed for Helicopter Engine

I'd consider one of the many small gear motors you can find on eBay, that way the blades will be turning slow enough to look pretty real.

eBay: 262485949749

Couldn't you run a long wire shaft (about the diameter of a wire coat hanger wire) from underneath the pivot of the blade, downward though the body of the chopper, into the building it's sitting on, and house the motor there? It'd be way easier to work on and get access to without heat problems. And more than a few feet away, you'd never see the wire anyway.

It's how I'd build it.

Michael,   Red lights on the building normally do not flash, they are steady. You might consider having the white light illuminating the walk way rather muted.  You don't need it very bright so the pilots don't lose their night vision.  I think you should consider Lee's suggestion of putting the electric motor a few inches below the belly of the aircraft.   John in Lansing, ILL.

rattler21 posted:

Michael,   Red lights on the building normally do not flash, they are steady. You might consider having the white light illuminating the walk way rather muted.  You don't need it very bright so the pilots don't lose their night vision.  I think you should consider Lee's suggestion of putting the electric motor a few inches below the belly of the aircraft.   John in Lansing, ILL.

Thank you for that. Unfortunately the building has been completed with the flashing lights. It was done on consignment and unknowingly I approve that feature - but it does look good. I'll write it off as one of those anomalies about which all but the most serious modeler is unaware. As far as the other suggestion, mounting a motor just under the chopper in the building, I'll pass that along. I'm surprised a little that I haven't seen anything like this at York yet. Maybe a niche for us to fill? Any project idea investors out there? (hah hah)

You should be able to fit a low-cost DC can motor (a couple bucks on eBay) right under the main rotor assembly.  It doesn't take much power (a few Watts at most) to rotate a 1-48 scale plastic rotor.  Running a tube to a motor under the pad can certainly be done but I think you'll find it compounds the motor-rotor shaft alignment.  That is, wobble is going to be an issue as I don't believe any static-model manufacturer is concerned about balance.  Use an AC-to-DC converter module (a few bucks on eBay) like we use to convert AC track voltage down to low-voltage DC for LEDs.  GRJ's suggestion to use a geared DC motor is smart.  If you don't use a geared motor, what you'll find is the voltage needed to start the motor spinning from idle will be too much voltage once it gets going.  So unless you have a motor speed controller (which obviously is going over the top), just use a geared motor which solves the startup issue.  Also, if you're running wires into the model for lighting, that's another point to just putting the motor inside.

I can guarantee that your chopper will not perform its intended function unless you also spin the tail rotor! 

Here is a short video showing a SH-60 Seahawk and Mi-24 Hind 1-48 models with spinning main and tail rotors.  These use DC can motors but have speed controllers needed, in part, to spin up and synchronize the two motors which I believe is the only practical way in 1-48 scale to model the shaft-gearbox of the prototype.

It can be challenging to mate the rotor assembly to the motor shaft.  Most if not all DC motors will have metric shafts so you might need to get some metric drill bits.  If you're willing to only have the rotor spin slowly, that will greatly relax the need for balanced mounting.  You can see prop wobble at full RPM in the videos. 

For the curious, here's the guts of the Seahawk.  Do not try this at home as it is a ton of work.  The electronics is like that in our trains where only two power wires go into the model with digital commands over the power wires to remotely control the motors, lights, etc. synchronized to sound. 

stan2004, well done sir! Thanks... And thanks to the rest as well.

That is amazing Stan! I can't imagine how long that must have taken you to figure out and then to pack it all in the helicopter. I think I am most fascinated with the operating tail rotor! Certainly does look like a ton of work not to mention a lot of thought too. 

Stan2004, where did you get the White/Red strobe led? Does one make them in a glow form as well? [i.e. a non blinking-non strobe- solid led that changes white to red and in 2mm or smaller form?]

rtr12 posted:

That is amazing Stan! I can't imagine how long that must have taken you to figure out and then to pack it all in the helicopter. I think I am most fascinated with the operating tail rotor! Certainly does look like a ton of work not to mention a lot of thought too. 

Indeed.  IMO the tail rotor is the trickiest part of animating a helicopter.  The models shown use a pager/smartphone vibrator motors which are about 4mm diameter.  But I am stumped with how to animate the fenestron or ducted-fan tail rotor in the Coast Guard HH-65A Dolphin (1-48 scale) and the model kit is a shelf-queen. 

prrhorseshoecurve posted:

Stan2004, where did you get the White/Red strobe led? Does one make them in a glow form as well? [i.e. a non blinking-non strobe- solid led that changes white to red and in 2mm or smaller form?]

Hmm.  It's been over 10 years and I had to dig out the photo/videos.  IIRC the Seahawk changes it's strobe light color between warning mode and anti-collision mode depending on take-off/landing vs. in-flight.  I believe the prototype looks something like the following. 

Because this would be extra-ordinarily difficult to model in 1-48 scale, the model used a red LED and a white LED feeding a fiber-optic rod (2mm diameter or whatever it was).  The LEDs were surface-mount type so quite small and you can put two side-by-side feeding the fiber.  If done today, one might be able to find a single-package RGB LED that could be driven to render Red or White.  As shown in the earlier photo, the strobing effect is performed by the electronics as that's how the prototype behaved.  Nothing stops you from just driving them solid on.

I figure there may be some application to train classification lights or the like which change color.  In other words use more than one light source/color but "pipe" the light to the output lens so that it doesn't appear to move when changing color.

There are actually RED/WHITE bi-color LED's, but so far they have seemed to be fragile, I used them and several died for no apparent reason.