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..The sun is out!...Let's go FLYING....False alarm...
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Heli-Log 4:16:2014

Posted 04-16-2014 at 02:40 PM by rcnut

My Trex700G maiden!

So the day finally arrived…maiden time! The weather decided to play nice, semi warm, mostly sunny, with 5-10 mph winds. Mark was busy fly his Whiplash gasser, Bob was chatting with Bill, John, and Steve. So I arriving last, no one was in a hurry to bother me just yet, so I pulled out my Trex700G and proceeded to fill the tank full of gas. I pumped the bulb until there was a solid stream of full returning back to the tank. One final look at everything, including the radio settings, and I’m good to go!

As Mark finished his flight, everyone decided to see what I was up to. Too late, I’m ready to start my heli, no questions at this time! I grabbed the start rope and proceeded to bring the motor to life. Whoo Hoo! It runs! Off to the LZ! (Landing Zone) I handed Mark my Tablet to record the event (which both of us can’t find in the Tablet!), and now the moment of truth. I added throttle slowly and the blades started spinning. More throttle and my heli is airborne! I spend a couple of minutes checking the controls as to the feel. I slowly pirouetted the heli clockwise and counter-clockwise, and everything looks good. I add more throttle and push the nose forward. My new gasser is taking to the sky like a pro. Nice and gentle, steady as a rock.

I made several laps around the field and brought it in for a gentle landing. I reduced the throttle to an idle to let the motor cool down for a minute. Then it was back into the air for more big laps around. This went on for what seemed like a very long time! I had the timer in the radio set to 7 minutes, my experience with my Whiplash. I must have landed around 8 times to let it cool off. Something must be wrong; the timer went off long ago and I still have a lot of fuel left! Maybe the motor is too lean! During one of the landings, we decided to check the motor temp. Wow, it was 198 degrees…that’s cool, not even a concern, but why so long of a flight time? Just past the half tank mark, the motor changed sounds. It was breaking in and went from a nice smooth medium pitch run to a sluggish lower pitch run.

No problem, for the second flight, I’ll adjust the needles lean by a small amount…1/16 of a turn on the low and a bit more on the high. That did the trick! Now the motor is running even better. It sounds great and the temp is around 210 degrees. I am really happy with that! During this flight, Bob was timing me, 2 minutes in the air, one minute on the ground, repeat until close to empty! However, during this flight, I couldn’t help resist the erg to try a couple of loops and rolls. But that turned into some traveling backflips, inverted funnels and figure 8”s, inverted loops and rolls, inverted hover, stationary forward and back flips.

But these were done as easy and gentle as I could, without bogging the motor. The guys were eating it up, the big gentle maneuvers vs. the fast crazy wild stick banging in your face smack-down! Yea right, like I can do that!...well ok, some of it. The controls felt a lot like my Whiplash only slower. The new Hanson RC300 3D Max motor has more than enough power for my heli. And the fuel economy is unbelievable…20 minutes per flight! I feel sorry for the plankers at our field when it’s my turn to fly!...not really. LoL! So that ended the second flight for the day, I was looking to get 4 flights in, but I had a couple other heli’s that needed my attention. During the following week, I called BH Hanson and talked with Al about this new motor, especially the fuel millage! Al said this is normal. For some reason this motor sips the fuel vs. guzzling it. Cool!!!

Bob’s Whiplash gasser was finally ready to go once more. I was at the point of not wanting to fly it anymore! Every time it went into the air, it would break within 30-40 seconds. The main gear would strip, or one of the small bevel gears would break, or the sprag would slip and cause a gear to go. It was one thing after the next! Even the motor wasn’t working right. I was constantly chasing the needles. So I told Bob I wanted his heli so I could go through his motor. Tear it down, check everything out, then put it back together and run it. Now to regress just a bit…

I had bought a spare carburetor gasket set just in case I needed to change carbs, kind of like having extra spark plugs. I was instructed by Toxic Al to use the newer carburetor Bob bought after Al fixed Bob’s motor (a retaining clip that holds the “Boss Pin” in the piston broke and was scratching the cylinder wall reducing the compression each time the motor ran). So I proceeded to pull Bob’s carb off only to find the answer to why his motor was running so bad. The gaskets were installed wrong (not by Toxic Al). I removed the original carb and isolator plate, cleaned everything and installed the new gaskets and carb. The test flight in my driveway was a success. I burned a tank of fuel with his motor sounding perfectly, like when it was brand new. Then Bob came over to witness a second test flight only to have the sprag go out in 30 seconds! Bob said he would take his heli home and replace the sprag, as it would give him something to do.

Now, after my 2 great flights on my Trex700G, it was time to try Bob’s Whiplash! I really wasn’t looking forward to this, but we must press on sometimes. Bob’s motor started on the first pull of the rope! I kind of expected that…and his motor was purring like a kitten! Out to the LZ and see if this heli will fly! I throttled up and in the air Bob’s heli went! I was a bit hesitant to try anything, so I pirouetted to the left and right slowly, waiting for that magical 30 seconds to pass. It was still in the air after 30 seconds, and nothing has happened. I looked at Bob and said I was afraid to do anything with it for the fear of something going wrong! Bob agreed, and said “well? It’s up to you”. “Ok” I said, “let’s see what she’ll do!”

I pushed the nose forward, added collective, and started flying slowly at first. I made several passes around the field and everything was holding together. I came in and landed for the one minute cool-down, then back into the air! This time around, I started picking up some speed and making big 50’-100’ circles and big sweeping turns. Another 2 minutes are up and land, cool-down for 1 minute, back in the air. By the time I got to the end of the tank, I was feeling very confident flying Bob’s heli once again. The second flight, I let Bob fly his heli.

Mark was having issues with his motor not wanting to run right. He brought a newly mixed batch of fuel (32:1), a new carb, and gasket kit. Mark bought his Whiplash used and was told, of course I was there, his motor is fairly new with maybe 10 flights on it. Well Mark wanted me to perform the same procedure on his heli as I did on Bob’s heli…changing the gaskets and carb, ok, no problem. So I removed the carb and found the gasket was completely soaked with fuel? I removed the isolator block and gasket and found the same thing there! What the heck??? I cleaned the port on the motor and installed a new gasket with a new anodized isolator block. Then I installed the new carb, gasket, and air filter plate. Connected the throttle linkage after resetting the travel limits in the radio, and connected the fuel lines.

We filled the tank, primed the carb, and his motor came to life! Boy…it sounds a whole lot better! Now to tweak the low & high needles…Mark was a very happy camper at this point. No sooner did I land, at the end of the first tank, Mark carried his heli back to his truck…he had his heli refueled and back out flying around! I think Mark was very happy to have his gasser working right!

Once home, it was time to look over my Trex700G. I wasn’t too happy with the 3 linkages going to the swashplate, from the servos, as the plastic link is only threaded on by 6-1/2 to 7 turns. This may be enough for most people, but it made me nervous with the type of flying I am planning to do…a lot of high energy maneuvers! I’m also not too comfortable with the standard Futaba servo horn…it potentially flexing. This is a heavy gas helicopter! However, they may be ok for nitro and sport flying, but I’m a bit old school and like a bit more beefiness (wow, beefiness, is that really a word? Spell check and Google said it was!).

I found an extra set of servo to swash links in my Rave parts, and they are 5mm longer and 0.002” bigger in diameter! Perfect! Now I need to figure out which servo horns to use. While I’m contemplating this, I started installing the Jewel Generator system on my Trex700G. The generator (electric motor) is mounted to the plate, the coupler is mounted to the generator and this assembly is resting on top of the start shaft. I’m looking for places to mount the 3 phase converted, this goes to the voltage regulator. I also have 2 super bright LED’s (Light Emitting Diodes) and a voltage meter to monitor the regulated voltage.

To some people, this sound strange using an electric motor, one that you would use on a foam airplane, as a generator. Actually an electric motor has two elements inside, a bunch of wire windings (3 separate loops or phases; A, B, C) and magnets. As a motor, we would connect the motor to an ESC to drive/turn/spin this motor. The ESC sends a voltage pulse that is repelled and attracted to that phase. The ESC repeats this for all 3 phases, and in turn, this spins the motor. There is a lot more to this, but I’m keeping it simple.

Now to use that same motor as a generator, you need to mechanically spin the motor. The magnets energize the coils inside to produce a voltage on each of the 3 phases. It’s the magnet’s magnetic lines of flux is what causes a voltage to appear on the 3 phases. (Magnetic flux (most often denoted as Φm), is a measure of the amount of magnetic field passing through a given surface (such as a conducting coil)). These electric motors are what are called 3 phase motors. The output of the 3 phase motor (or electric motor) is connected to a converter to turn the 3 phases AC voltage into a DC voltage to power the voltage regulator. The output of the voltage regulator is connected to the receiver and supplies the receiver, servos, and charges/keeps the battery charged. A simplified explanation.

More on this later…
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