dboryta

[dboryta]

Well my story is not a happy one. (but exciting!)
When I tried my first lift off, my helicopter's blades disintergrated.

My experience is RC flying a modified sea plane and I got pretty good at it. My wife was the black box using a vidio camera and I could review my mistakes. I found this very valuable.

I subsequently inherited a number of different models planes including a JR Ergo 60 helicopter.

These were built by a relitive who recently passed away. My inspections indicated he had pride in building these models. He never flew them. I also got RealFlight G3 to practice landings with the plane flying towards me (which I found difficult but did master it using the simulator). I also practiced using the simulator and using the "training wheels".

When using the simulator, I frequently lost my rear rotor blades.

I continued to practice until I felt confident hovering with the tail towards me.

So, I checked out the Ergo 60 to make sure all surfaces are responding as per instructions.

I fueled it and found it easy to start and tune (carburator).

I slowly increased the engine RPM and everything looked good.

I tested the function of the tail roto blades and all looked good. At the RPM I was at, I was able to move the tail left and right a little and was able to twist the helicopter's position a little. All looked smooth.

Before I go any further, I did construct "training wheels" (4 ft by 4 ft) using oak dowels and foam golf balls glued to the ends. I tested the strength of the "training wheels" by dropping the helicopter from various angles about 1.5 ft. I used rubber bands to sequre the "training wheels" to the landing struts.
Now the rotor blades were not as tight as the instructions said they should be. They swung freely.

As I increased the RPM slowly, I noticed that the front of the Helicopter was trying to lift off slightly. Then the blades disintergrated!!!!! removing the tail complelly from the helicopter!!

The following reconstruction of the damage is based upon location, not sequence.

The short universal ball link conected to the flybar control arm was torn loose.
The flybar was bent in the form of a S.
The main wooden rotor blades were split apart and thrown a good distance.
The boom was bent in half as evidenced by an angular hit and no longer attached to the helicopter.
Destroyed were the tail fin set.
The tail output shaft was bent.
The tail drive belt was broken.
The ball link at the end of the tail control rod was broken but the other end was still attached to the servo.
The tail pitch control lever and the slide ring assembly were broken.
The rotor blades and assembly was OK!!
The tail boom carrier was destroyed.
The horizontal tail fin/brace clamp was destroyed.
The landing gear dampers were all destroyed.

I have repared the machine and purchased what lookes like a beautiful set of fiber reinforced main rotor blades. My wife was upset that she did not have the chance to video the first lift off try.

Any advice before I try lift off again?

Dan

[Aztek1701]

Hi there,

Welcome to the fever

Wow, its really difficult to say whether this was a mechanical failure cause by an assembly mistake, a pilot error or something else. From your description, 2 things spring to mind but they might be totally wrong lol.

1. Was the washout base in the correct position. If you look at the mainshaft, the washout base is where the 2 little "prongs" guide the slide that takes the mixing arms. It moves up and down with the collective. The problem is that in some models, the position can be adjusted, if its done too much in the wrong direction, you end up with your elevator being your aileron. Not when you look at it on the ground though, only when its spinning. Id also say that Im unfamiliar with the ergo 60 and your machine might not even have a washout base. But its worth checking with the instructions that its in the right place.

2. If your blades disintegrated, before they hit the ground, my thoughts are that they were either damaged in a way that was invisible (crack with the grain under the covering) or the plastic root reinforcements wernt attached properly and the root let go. If this is the case, the fiber blades wont suffer from this.

Before you fly again you need to check that all the screws are tight, use threadlock on metal to metal connections. That your blades are balanced. That the control surfaces work as expected on the ground. One check I always do before just before flying is when the heli is spinning (but not a flying speed) I check the elevator, aileron and rudder that they are moving the rotor disc in the direction I expect.

Hope this helps... maybe some of our more experienced members will be able to give you some other ideas.

Take care.... Azzy

[Aztek1701]

Hi there,

Welcome to the fever

Wow, its really difficult to say whether this was a mechanical failure cause by an assembly mistake, a pilot error or something else. From your description, 2 things spring to mind but they might be totally wrong lol.

1. Was the washout base in the correct position. If you look at the mainshaft, the washout base is where the 2 little "prongs" guide the slide that takes the mixing arms. It moves up and down with the collective. The problem is that in some models, the position can be adjusted, if its done too much in the wrong direction, you end up with your elevator being your aileron. Not when you look at it on the ground though, only when its spinning. Id also say that Im unfamiliar with the ergo 60 and your machine might not even have a washout base. But its worth checking with the instructions that its in the right place.

2. If your blades disintegrated, before they hit the ground, my thoughts are that they were either damaged in a way that was invisible (crack with the grain under the covering) or the plastic root reinforcements wernt attached properly and the root let go. If this is the case, the fiber blades wont suffer from this.

Before you fly again you need to check that all the screws are tight, use threadlock on metal to metal connections. That your blades are balanced. That the control surfaces work as expected on the ground. One check I always do before just before flying is when the heli is spinning (but not a flying speed) I check the elevator, aileron and rudder that they are moving the rotor disc in the direction I expect.

Hope this helps... maybe some of our more experienced members will be able to give you some other ideas.

Take care.... Azzy

[chaos]

the rotor blades were not as tight as the instructions said they should be. They swung freely

Hello dboryta. The blades should not swing freely. At low head speed this can allow the blade to drop down and whack the tail boom. The blades should resist movement, but not be tight. How tight? If you hold the heli on its side with the blades stretched out the blades should not swing, but if you give the heli a little yank while holding it sideways then the blades should move. Check for even-ness by putting the blades in the left/right position (sideways) extended, then straddle the heli and pull both blades towards the rear - as if you were going to store it - by putting a hand on each blade at about the same point from the center and they should move more or less together. The blades need to be loose enough that they can move to come into balance when they spin up, but tight enough to keep them from moving at low rpm.

As I increased the RPM slowly, I noticed that the front of the Helicopter was trying to lift off slightly.

For the front to lift up at low rpm it seems the swashplate may have been tilted to the rear... were you holding the cyclic towards the rear, as one might do with an airplane? If the swash was tilted rearward, then as the blade comes around to the right side of the heli it's pitch would be lowered. Let's say the pitch was negative. That would mean, if the blade pivoted forward in its holder it would be headed for the boom. Why would the blade pivot forward in the holder? Maybe you backed off the throttle a bit when the nose lifted, and the blade, in trying to haul the head on around instead of the head hauling the blade around, slipped forward. Being free to pivot would easily enable that to happen.

Perhaps I'm all wet with this analysis but anyway the blades should be snugish. And when you spool it up leave the cyclic stick centered (swashplate level). When the head is up to speed the centrifugal force will keep the blades in their "sweet spot", which is when the center of gravity of both blades is on a line through the center of the hub. If the blades are too tight they will have trouble getting to the sweet spot and the heli will shake like the devil. It would be slop luck to get the blades positioned correctly to start with, so it may shake at low rpm when you first start up. But as the rpm increases the centrifugal force should pull the blades into the sweet spot and it will then run smoothly; assuming the blades are balanced.

Aztek1701 already covered this item, but it's worth repeating, check to make sure the controls are doing what they're supposed to do before lifting. Be careful, just enough control to see the rotor disk tilt a little... it's easy to roll the thing over sitting on the ground... but training gear will save you. None the less, avoid a bad habit.

When you do lift off, try to keep it low.. just light on the training gear and get a feel for the controls. Watch the rotor disk, the blur of the blades, and keep it near level. Avoid steep rotor disk angles. Lift maybe a foot off the ground. The disk will have to tilt slightly to the right to keep from drifting left, due to the tail rotor. But the disk should be kept near level. The blades are what's doing the flying and whichever way they're tilted is the way you're gonna go. The greater the tilt the greater the acceleration. To keep from getting terrorized keep the tilt of the disk at a shallow angle and set it down when confusion takes over.