Well now children, this month I'm going to talk about model helicopters. Now, it's no use complaining, I know that W3MH is supposed to be a magazine where people talk endlessly about themselves but this time it's toy helicopters, so you can like it or do the other thing...
The subject of this homily is the Schluter 'Magic'. Now, right away we are into controversy because the machine was actually kitted by the robbe company after they had bought the rights to the Schluter name. Many people have the impression that it was the last machine actually designed by Herr Schluter himself, but anybody who has built one has no doubt that it is more robbe than Schluter.
The design has some quite intriguing features, such as a two stage gear reduction which looked like becoming popular at one time, and a teetering tail rotor. "Lots of machines have a teetering tail rotor", you may say, but this one is probably unique in being undamped. There is a nylon pad between the tail hub and the divided end of the tail shaft but this lasts about half a tank before it stops doing anything. This means that the tail rotor can flap about like a disconnected rudder and produces some interesting effects, particularly in hovering manoeuvres. There is little that you can do about this other than find some other Schluter bits that allow you to stop the teeter. A study of the machine flown by Volker Heine in the Schluter Cup a few years back shows that this is exactly what he had chosen to do.
It is quite heavy at around 12 pounds but hovers nicely and has the rare attribute that there is no trim change during autorotation - you can almost leave the cyclic controls completely alone until you need a touch of flare to stop the forward movement.
The problems start when you try aerobatics. Loops aren't too bad but rolls are at best untidy and downright hazardous at worst. What usually happens is that it gets round to the inverted point reasonably but then stops dead in it's tracks and falls out sideways. My own thoughts on this are - or were - that the Bell/Hiller mixing ratio is wrong, which is substantiated by the fact that the paddles move through a colossal range - something like 6 - 8 times as much as the blades.
All of the early flying was done using a PCM10 and numerous different set-ups were tried to improve the situation - all to no avail. Things took an unexpected turn when I was loaned a robbe FC-28 for a time. I duplicated the PCM10 set-up on this new set by using a pulse counter plugged into each receiver outlet in turn (if you have an NHP simulator, the 'intest' program will allow you do the same thing). The big surprise here was that the 'Magic' would now roll. They still weren't exactly superb, but at least they were recognisable.
This situation continued until the FC-28 had to be returned. Aware that I had refined the program during it's use, I repeated the proceedure and copied the set-up onto the PCM10. I now had two slightly different set-ups to try. Maybe you've guessed - it wouldn't roll with either of them! A quick flight with the FC-28 revealed that it still would with that set!
Having done a lot of flying with the PCM10, I reached the point where I really needed those two model memories so decided to fly the model with an old PCM9 that I have. This is one of the very rare 'Z' series which will work with all the modern JR PCM receivers. So, once again I went through the process of copying the set-up onto the PCM9. I did a lot of flying with this arrangement but never tried rolling it.
Eventually the day dawned when I broke it. Actually I had tried flying the model with a HAL2100 autopilot fitted and found it an interesting, if frustrating, experience. Upon removing the HAL I replugged the cyclic inputs into the receiver and made a note to check that they were right before I flew it again. I didn't and they weren't!
It wasn't too bad and the repair was limited to a boom and tail drive together with a new tail pushrod. I don't know whether Midland Helicopters have a vast stock of unsold 'Magic' spares but they are surprisingly cheap (NO Trevor, forget I said it). The real pain was that the canopy was smashed and I had to paint another. So, out we go to fly my nice clean rebuilt machine with a nice new paint scheme.
That Schluter/Webra with Schluter muffler really works well. So much so that I was soon burning up the sky and, almost without a second thought, I tried a roll. Well, not exactly FAI standard but round it went and I soon found that it emerged with enough airspeed to do another. At this point it is all too easy to become totally paranoid so I simply had to try it again with the PCM10. No, it still won't!
Now, there is a difference between the FC-28 and the JR sets in that the JR transmitters all have a limited amount of throw on the throttle stick whereas the FC-28 has the same throw as all the other channels. This means that you have to move the throttle stick further to obtain the same effect as on a JR transmitter. This might make some difference, but what about the two JR transmitters?
Anybody any ideas?