Sierra RotorCraft Club

Introduction

At the last simulator day – #15 – Jewgo was bragging how good he could control the simulator, at least with respect to pitch, role and lift, and he could do this without ever hovering a real helicopter. Mike and I tried to tell him that without the Yaw input, he is not experiencing what it is like to hover a helicopter. (Although I have to admit, even without yaw input, Jewgo did pretty will).

Today, we gave Jewgo a little more of a challenge by connecting the Yaw motor to the power system. Now the simulator will have full “ALL” axes control. To make things even more changing, we connected a laser pin light the simulator and put a target on the hanger will. Now the challenge was who could keep the laser light on the target the longest. To see the fun games, see the videos below.

Jewgo thinking his good!

Now lets see how good he was! (no! – it’s the middle tape)

Now it’s Mike’s turn

Yaw Motor – plug

Ok – so you know what we did for part of the day. However, before we could play, we needed to install a plug on the Yaw Motor and check that system out. After the first rounds of play, we discovered that the Yaw motor was always on, going one direction or the other. It never would stop when the simulator was not moving in the yaw axes.

A pond investigation, we found that one of the micro switches (one for each direction) was encaging when it wasn’t supposed to be. This switch was all caked up with grime and all kinds of stuff you wouldn’t want to put your hands on.

So Mike went to work performing his magic with a little of cleaning here and their plus a little tweaking of a micro-switch to insure it would not be engaged when the simulator was not moving in yaw (that is with the peddles neutral).

Note that the Yaw belt is slipping so even with the micro-switches working; it was still hard to control the simulator in the Yaw axes.

Fired up air compressor on simulator

All this playing tag with a spot on the wall was done with my big compressor. Now we wanted to see if the compressor on the simulator would perform as it once did. However, it was hard to see the compressor regulated gauge, so Mike replaced it with a new one. After all, how can we adjust the regulation, if you can’t read the gauges?

Check simulator air compressor to see if it will hold at 40 psi

Although the simulator air compressor could regulate at 40 psi, it couldn’t hold it very long due to a small air tank. – Keep in mind that all regulation valves are manual and cannot be adjusted for fine tuning – as we found out as we were playing who could hover the best.

Power Problems

Although the compressor could hold the pressure to the system, it could not remain running without popping the circuit breaker on Jewgo’s power generator. What was causing it to blow was when the compressor motor tried to restart; it would stall and or over heat. Whenever it stalled, the current demand was maximum and if it didn’t blow the circuit breaker, the motor would over heat and the internal temperature sensor would trigger and not let the motor start.

So the question was, way would the motor work just fine until we got it to Jewgo’s hanger. With some investigation with a watt meter, I noticed that the operating voltage to the air compressor motor was only 80 volts – not 120 volts – causing a lot more current to flow in order to meet the power requirement of the motor.

Re-wire the simulator power to 240 volts

So I had the brainy thought that I would re-wire the supply cord to the simulator. Since Jewgo’s generator had the capacity to generate 240 volts, I figured I would split the 240 volts – like in your house – where 120 volts would be supplied to each of the motors (the air compressor and the Hydraulic motors).

In theory, this idea would work, but after I got home and thought about it longer, I realized that this wouldn’t work. First the simulator only has two brushes to supply the power to the system (note that the simulator can rotate in yaw forever, continues 360 rotations). So I would have to use the chasse as the reference point for the two legs of the 120 volts. Although the system is grounded to the generator with respect to a return current, there was still the risk of getting a shock while standing on the earth even though the generator is not grounded to the earth.

The second problem I realized is that the primary winding of the generator was still only able to supply 20 Amps to the simulator, no matter how you wired it. And even if the primary windings could support the current, the 20 Amp circuit breaker is on the primary side of the generator. So it would still blow.

Now as far as the 80 volt line drop, our supply cord to the simulator was a good 30 or 40 feet long and was only 16 gauge wire. Although this size wire is only good for 1300 watt it was still in range of the required power from the simulator. What we probably need is to use a 12 gauge wire and as short as possible cord to cut down on the voltage drop.

So why did the simulator work before we got it to the hanger? Well (Duh!) the simulator always got its power from PG&E, therefore had all the required operating voltage and power to run the thing.

Now the thought is to get a 12 gauge supply cord that is short. If this doesn’t work, then the only other solution is the get a bigger generator. I don’t think it would be wise to connect two generators with a common return (ground) and supply power to the simulator, with one generator for each system.

Anyway, that’s where we stand, needing to get a better supply power (generator) and fine tune the regulated air supply to the role and pitch axes.

… jim burrow