Arcade Chopper Project!

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Welcome to the
Arcade Chopper Project Web Site!

Witness my attempt to build a high performance arcade helicopter machine, similar to some that were manufactured in the 1960's and 1970's. This may take some time and it may not be a successful project. Success or not, I'll give it my best shot. Thanks for visiting! N. Pepin

Features to Date

Note: The original parts are from a 1967 Helicopter Trainer Arcade Game and include, 3 legs, the mechanical parts of the throttle controls and part of the tower.

Helicopter:

Dual Rotor High Performance Motors
Hydraulic Pitch Stabilization
On-Board PIC Processor Controller (serial controlled)
Luxeon Star LED Laser
Luxeon Star LED Bomb
Servo Pick-Up Hook
Hook Light
Hit Detectors and Explosion Effect Light
Beacon Lights
38Khz IR transmitter for target detection

Game:

Dual PWM PIC Processor based Speed Controllers
Right Throttle Equipped with Laser, Bomb and Servo Hook Controls
Right Panel Controls Include Engine Switches, Fuel and Ammunition
Left Panel Controls Include Game Switch, Start and Game Mode
Four Hostile Targets with IR detectors, Photocell Detectors, 2 (each) LED Guns and Explosion Lights
Automated Bulldozer Moves to Collapse Bridge, Includes Flashing Warning Light
Bridge Has Status Lights (Collapsed or Okay)
Lit Hospital
Small Rooftop Helicopter with Rotating Rotors (stepper motor Controlled)
Mountain with Stealth Fighters and Flashing Hanger Light
Airstrip with Flashing Beacon Lights on Fighter Plane
Pick-Up Vehicle, Must be Moved to Different Location Via Hook.
Audio System with Subwoofer
Three uMP3 players for high quality, overlapping sound effects with 750MB memory.
Sound Effects, (So far they include explosion sound effects, hook sound and bomb drop mis/hit explosion, front control panel narration tracks, engine startup and engine shut down sounds )
Laser sound effect module using a sound byte from the 1960's cartoon "Space Ghost".
Multi Channel Lighting Controller
Central Game Controller (needs programming)

Still To Come

Clouds
Backdrop
Moving Ambulance
Display for Score, Lift, Engine RPMs, Fuel, Ammunition, Time, Bonus, Game Level, etc.
Many More Sound Effects for Laser, Narration, etc.
Complete Body For Helicopter
More..

Performance

The machine is a lot of fun. It took a while to refine the mechanics and the electronics so that the flight controls were stable. The hydraulic pitch dampening, additional counterweight and reduction in power resulted in a high performance, precision flying helicopter. The motors are limited to run at about 20% of their rated power. When adjusted to full power, the machine is scary and a lot harder to control. It was necessary to slow things down and dampen things so that one could concentrate on the other controls like the laser, bomb and hook controls. Even the software that operates the electronic speed controllers for the motors was designed with a somewhat logarithmic response so that there is precise low speed control that ramps up logarithmically as the throttles are increased. This makes maneuvering easy. Picking up the bridge is much easier because with the hook lowered, you can precisely control the helicopter to latch onto the bridge lift, then you have lots of upper end throttle for the lift you need. About the bridge; a motorized bulldozer pulls down the bridge such that the ambulance cannot get by. Status lights show the state of the bridge. Collapsed, the bridge can then be lifted by the helicopter which requires tough maneuvering and a lot of throttle power to lift the bridge back in place. It's a neat effect feeling the power of the helicopter. Only the moving ambulance has not been completed. I'll likely add lift or thrust gauges to add to the effect.

The hostile targets detect the presence of the helicopter because the helicopter is continuously transmitting two IR beams, forward and below. When detected, a target will fire upon the helicopter, firing both its guns in rapid succession. The helicopter is equipped with 2 photo cells and a light to detect hits and respond with a flash explosion effect. With a software modification, I could monitor the hits and respond in some way. You can fire upon the targets (ground, building or mountain targets) with the laser or bomb. Each hostile target has a photocell to detect the laser or bomb blast. To enhance the explosion effect, 50 watt light cannons located on the roof, blast the targets when a target is hit. The targets are equipped with their own explosion lights however the light cannon create a much more dramatic explosion effect. Ultimately, the light cannons will be hidden with clouds. As it is, you can't tell where the light is coming from. Once hit, the targets appear as if they are on fire by shimmering their lights. All of the above includes powerful, rich sound effects from three uMP3 players and a powerful subwoofer and speakers.

The control panels include a level button (game levels 1 through 4), a start button, engine, fuel and ammunition switches. Sound effects and voice synthesis narration is included. The uMP3 players are used for the audio sound effects and sound tracks. They use SD memory cards so they can carry several hours, of high resolution sound effects and sound tracks. Since three uMP3 players are bridged, there can be as many as three overlapping sound effects or tracks or combinations.

I still need to build displays for the score, time remaining, fuel and ammunition levels and other things. There will be moving targets where by a terrorist is firing at you from a building. There will be a vehicle to pick up and move, providing another purpose for the hook.

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Background
If you're a fan of Johnny Astro, Vertibird, Dareplane and other flying toys, you might also like some of the arcade helicopter machines from the 60's and 70's. My interest with flying toys goes back to the early 70's when Vertibird was first introduced.

Although I was never one to frequent arcades, our many travels left us spending much time in airports. It is there that I first seen some of the arcade helicopter machines. There are five that I can remember;

Whirly Bird by Midway
Helicopter Trainer by Sterling
Chopper by Midway
Minicopter single rotor bubble top machine
Minicopter twin rotor chopper (very high performance!)

Below is a table with all of the helicopter type machines I could find information on;

Whirly Bird by Midway (1969)
Helicopter Trainer by Sterling (1968)
Jaycopter by Jacobs Welding & Engineering, Edmonton Alberta Canada.
Midway Chopper (1974 )
Minicopter by Minicopter Enterprises, Edmonton Alberta Canada
Jaycopter by Jaycopters Recreation Ltd, Edmonton, Alberta, Canada (1968) Manufactured by Coinco St. Louis Serial No. JRM67040 (meaning #40, built in 1967?) This is the same company as Minicopter Enterprises.
Sega Helicopter (1968) This a dual rotor machine. Looks like fun!
Hawk Avenger (1991) Bromley
Williams Space Pilot (1968). Click here for further information.

Most of the games were similar in that you flew a helicopter around a circle. The helicopter was attached to a rod that pivoted on top of a center pylon and a counter weight helped lift the helicopter. You could control the helicopter's pitch and speed. Trainer, Whirly Bird and Chopper all used a similar helicopter, and possibly the same motor and pitch control mechanism. In Trainer and Whirly Bird machines, the object of the game was to touch one of several ground based pins that were identified by a light that would sequence from one pin to another. Whiskers on the helicopter passed a small current through the pins. When you navigated and hit the right pin, you scored. Midway's " Chopper" was much more advanced. Mechanical aliens would move up and down. They were equipped with light sensors so that you could shoot them with your pulsating light beam. The light beam was pulsating all of the time. About a year ago, I purchased and fully restored a Midway Chopper game. After I restored it, I sold it because the game was not as exciting as I thought it might be. The helicopter was not very powerful and relied tremendously on the counterweight for lift. The mass of the chopper, pivot arm and counterweight limited the mobility of the helicopter. These games are very popular and very collectible. I do not want to give the impression that they are not fun because they are. My past experience with a couple of other machines left me wanting something different than the Trainer, Whirly Bird or Chopper.

The bubble top machines were manufactured exclusively in Canada. I recall playing them in airports, perhaps 15 or 20 years ago. After years of searching I finally found one of these machines in the aviation museum in Edmonton Alberta. The manufacturer is Minicopter Enterprises and the machine is called "Minicopter". The single rotor machine used a heavier pivot arm and a much more robust helicopter. It had a single large rubber wheel. The rotor was similar to a propeller for a radio controlled gas airplane. You could hear and feel the power of the motor. The power to weight ratio was much higher than the Sterling or Midway machines. With that much power, the feeling was closer to true flight. I think this is what made Mattel's Vertibird so much fun. In Vertibird, the motor was not in the helicopter but in a remote base. The rotor was driven by a thin steel wire and a set of springs that acted as universal joints. Without the motor in the helicopter, the helicopter mass was greatly reduced. With that, the helicopter had a high power to weight ratio with little mass to move about. The result was a fast and responsive helicopter that felt like real flight.

An even better bubble top machine by a manufacturer I have yet to determine, had a helicopter with twin rotors. I don't have a picture of that machine to show. This was the best arcade helicopter I have ever seen. If you have one, please sell it to me! There was no mechanical pitch control. Instead, there was an independent throttle control for each motor. It was an amazing machine with a lot of power. The object of the game (both for the single and twin rotor machines) was to touch down at lit buttons to score points. This would not be possible or practical without the power to weight ratio that these machines had. When you dropped the throttle, the helicopter fell like a brick and then could take off equally fast. To me the effect was amazing. That machine is the primary inspiration for my project. I must say that I am excited about building my own now.

January 1, 2003
I've given up ever finding a bubble top machine so I have decided to build one using a combination of existing arcade machine parts and parts that I will manufacture myself. Recently, I was able to purchase a pivot arm, pylon mechanism and chopper from a Helicopter Trainer via Ebay for $20.00. Only a week or so afterwards, I purchased a set of controls for a Whirly Bird Machine, also for $20.00.

This is the chopper and pylon mechanism I bought on Ebay. This is the actual picture as shown on Ebay.

These are the controls I bought on Ebay.

January 2, 2003
I built a mock up base to temporarily mount the controls and pivot arm assembly so that I could test the original chopper. Maybe this one would perform well? I was missing the linkages for the pitch control but was able to make ones just for testing out of wood. The controls came with a speed controller that I was able to use. I hooked it up to a variable power supply. The propeller was broken in 2 but I was able to repair it with Crazy Glue. I do not have pictures of the complete mock up because I did not realize I would be documenting this project at the time. Seconds after I powered up the chopper, I concluded that it was like the Midway Chopper, rather dull. I even played with different propellers and higher voltages. The motor is just too small. The motor draws up to 500 mA at 12 volts.

On a side note, the fellow who sold me the helicopter and pylon assembly has found some other parts. He has offered to give me the original machine legs, coin door and coin box and a few other parts!

The original chopper ready to fly.

The controls with the temporary wooden linkage.

January 3, 2003
It was time to experiment. I built a test chopper to see how a twin rotor helicopter could perform. I used hobby shop brass and 2 Mabuchi toy motors fitted with toy store propeller. It worked great! The motors could not handle the load and ultimately overheated. Each motor drew 2.5 amps. I used slot car speed controllers to test the concept. It worked well and had a similar feel to the high performance bubble top machines I remembered.

This test chopper was built with hobby brass and 2 small Mabuchi motors. It proved to me that the twin rotor concept could work.

This is a Chinook helicopter that I may model mine after.

January 5, 2003
Powerful motors are the single most important components in my opinion. After a little research, I decide to buy a motor and gearbox combination designed for electric RC airplanes. I fitted the unit with an 8 inch propeller with a pitch of 4. When I tested it, I was shocked at the thrust it put out. It was unbelievable to say the least. I immediately went back to get another one for the other rotor. I had to dig out my 12 amp, 12 volt power supply to test the unit at full power. I found that it drew about 10 amps. That's 20 times that of the original Trainer motor! At this point, I decided to fully commit to this project. To start, I needed to modify the electrical parts of the pylon. by adding a ring stator and brush. Originally, it had 2 brushes. One was used as a common and the other as a motor feed. Since I was using 2 motors now, I needed 1 common and 2 motor feeds. I was able to build and add another stator pickup and brush from spare parts. It is interesting to note that the case of the pylon assembly is electrically isolated from the other contacts however there is a little resistance through the internal bearings. I determined that I could use this as another low power conductor for perhaps a light gun.

After I completed the electrical work, I wanted to extend the pivot arm length from from about 13 inches to over 19 inches. I also needed to build a custom universal joint to attach the yet to be built helicopter. I decided to build these parts out of stainless steel tubing. To do this, I needed to purchase a map gas torch and silver solder braising rods. I could have farmed this work out but I decided that it would be wiser to buy the tools because there will be many more parts to build including the helicopter. The pylon, pivot arm and universal joint are now complete. It is even newly painted. I also restored the light tower that came with the helicopter purchase.

Here are some close ups of the universal joint, silver soldered to the pivot arm. The mechanism is very strong. It is made from stainless steel tubing. The two opposing axis are lined with copper tubing which act as bearings.

This diagram shows how the universal joint and the helicopter work together.

This is the pylon rebuilt. The shaft is now 19 inches and has a new and much stronger universal joint. Everything is made of stainless steel and welded with silver solder.

Inside the pylon I added a third stator. I will need 1 common, 2 motor feeds and the casing can act as another conductor for the light gun. I tested the brushes to see how they would handle the substantial increase in current. No problem.

These are the motor/gearbox combinations that will power the twin rotor chopper. They are designed for RC electric airplanes. They are unbelievably powerful. In fact, they draw over 10 Amps and put out a combined thrust of over 40 times that of the original helicopter.

This light tower (shown here restored) came with the Ebay sale of the helicopter and pylon.

January 7, 2003
There are a pile of things I need to build and investigate to move things along. I have put some thought into the speed controllers, helicopter design and manufacturing techniques and possibly a theme for the machine.

Speed Controllers - I need to build 2 speed controllers that are fairly specialized. DC motor speed controllers that can handle 10 to 15 amps at 12 volts require pulse width modulation and power hexfets. The circuit is actually fairly simple when you use a PIC. A PIC is a small, embedded microcontroller. Generally, you take signal from a potentiometer and feed it into the PIC. You then program the PIC to generate a PWM signal who's duty cycle is proportional to the voltage in (from the potentiometer). The output signal is fed to the gate of a power hexfet but likely 2 or 3 in parallel to increase the power handling capability. There is a diode and a few other small components but that's about it. The greater challenge will be to attach the potentiometers to the 2 control levers.

Helicopter Design - I'm pretty sure I'll build a Chinook helicopter. I cannot find a model of a suitable scale but then again, a model may not be practical to use as a body. The body should be very light weight and never have any stress on it. I am thinking about a 2 piece vacuum formed body. To do this, I would need to fabricate a 3 dimensional cast made of maple, then cut the cast down the middle, lengthwise. Then, I would bring it to a local company who would put the 2 halves on their vacuum forming machine and generate the 2 parts. The nice thing about vacuum formed parts is that you can paint the inside so that the paint never scratches. If you want windows, you don't paint those areas.

Game Theme - I recently learned that Chinook helicopter are or were used in Afghanistan. It is possible they were used in Desert Storm too. I could call the game "Desert Attack" or "Desert Adventure" or "Desert Storm" I guess. Another more generic one is "Chinook Adventure" Maybe if the helicopter doesn't even look like a Chinook, I'll call it something else.

January 8, 2003
Tonight I breadboarded a speed controller. I had a few problems and perhaps still have a small adjustment to make, otherwise I think I got it. I used parts that I had for this initial prototype. I used a PIC16F84 microcontroller, 3 hexfets and a few other parts. I'll include a schematic when I build the final units. I had some problems with electrical noise and establishing a good range of control but otherwise it went well. I used 3 hexfets in parallel because alone, one was operating a little too hot. The only problem I see it an intermittent energy bump when the motor is running. I'm not sure what's going on with that. Now that I have the basic design in place, I'll order the right parts from Digikey. I'll select power hexfets with very low turn on resistance, a logic level gate and a low voltage rating. I've included some pictures of the breadboarded speed controller. As I said previously, it is a pulse width modulated speed controller. It is extremely efficient. When completed, each controller will control a 12 volt motor operating at 10 to 15 amps and yet the controller will run just slightly warm. That's amazing! I have also included a copy of the test program here. If you know anything about PICS (Peripheral Interface Controllers), you'll notice that I have a lot of extra I/O unused. Each speed controller only requires two I/O (One input and one output). I am not sure if I can generate 2 PWM signals simultaneously without some problems. If I can, a single PIC will be used for 2 speed controllers. Doing so will use up two more I/O and the rest (there are 13 available on this PIC) I may never use. I may ultimately choose a different PIC as well.

This is the prototype speed controller. Notice the potentiometer. It will be a challenge to connect two of them to each of the mechanical controls.

This is what my bench really looks like. It is well used!

Here is the propeller spinning under the control of the PWM speed controller. Notice the ghost like image of the propeller with the words "Master Airscrew"?

January 9, 2003
Today I ordered the required parts to build the speed controllers. They should arrive tomorrow allowing me to build them on the weekend. I think I can have the throttle controls completely done by the end of the weekend. I needed to dismantle the existing mechanical throttle sticks and make some changes so that their mechanical start and stop point were the same. These controls were made for the old chopper which had 1 rheostat and a mechanical pitch control. Now I needed to make changes to the throttle controls so that have the same travel and range. It went well. I have made the required modifications and removed the unnecessary parts. It looks pretty straight forward now. Mounting the potentiometers will only require a couple of brackets and a collar for one of the potentiometers to mate with the right throttle linkage. The left side already has one that will work for me. I also took the throttle levers apart, cut one of them down to match the other in length, polished and lacquered them.

The controls are now disassembled and the levers cleaned and polished.

I'm holding one of the potentiometers. The shaft will be cut and then I'll connect it to the collar shown just above the potentiometer shaft. A bracket will keep the potentiometer from spinning.

Shown here is the controls with the mechanical modifications complete. Here they are shown in their full throttle position.

The throttle controls are in there off position here.

Next I'll sand and paint the control box, build the potentiometer brackets and build the speed controllers. I am beginning to think about adding a button for a light gun. I am guessing I can drill a hole down through the top of the right control lever to feed wires through. Mounting a low profile button could be tricky. Ultimately the game will involve hitting land based targets with some whiskers just like the Helicopter Trainer machine but also will involve a powerful pulsating light gun that will allow me to shoot at sequenced targets. There would be sound effects, scoring and possibly some visual effects.

January 12, 2003
What a weekend! That was tough! I completed the controls. Well, almost. The speed controller gave me some problems so I started from scratch and re-designed them. The original problem I was having was heating of the mosfets. Once I resolved that, the motors made this annoying ticking sound. I determined it was caused by the PIC program momentarily jumping out of the program loop to read the potentiometer. It caused the pulse width modulation to stop for a brief moment. It was not noticeable before because the circuit was never driving the motors at full capacity. Anyway, I could not find a way to resolve it so I breadboarded a new circuit that was far more complex than the original. I'll post a schematic soon. It used tried and proven technology. ( A 7555 modified to generate a triangle wave gets fed into a variable comparator) After debugging the problems with electrical noise, it runs great! The only potential issue is that the mechanical range of the control levers is limiting the upper throttle range to about 70%. I'm not going to make any adjustments yet because I am guessing that I won't be able to run the motors full out anyway.

I painted the controls with a grey hammertone paint. I'll have to dismantle the controls one more time to give it a second coat of paint. I am also thinking about adding a mechanical throttle "OFF" switch so that in the mechanically off position, no electricity can pass to the motors. I trust my electronics but I felt a back up "off" is a smart addition. I also need to re-install the lever springs and think about the light gun buttons.

The completed speed controller (almost). This controller will be used to precisely control the speed of two Speed 400 RC motor/gearbox and propeller assemblies.

I added the middle bracket to mount the potentiometers.

Shown here is the circuit. It is actually two completely isolated speed controllers to reduce interference. I used twice as many mosfets as I actually needed however I wanted it to operate with little heat dissipation. The large capacitor in the middle solved the last of the interference problems. On the front right is a socket for some range setting resistors.

I'm really happy with the paint. It looks pretty good for its first coat.

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