Tips and Tricks

Batteries and Charger

With the  Ikarus-supplied 7-cell 250 mAH Sanyo NiCd pack I get about 4 minutes per charge. I use a Robbe Infinity 2 charger, this is an excellent unit. On the Auto setting, it takes about 20 minutes to fully charge. With two packs you can fly on one pack while charging the other. 

As of April 2001, I've made up an 8-cell Sanyo Twicell 700 mAh NiMH pack. Flight times in the order of 7-8 minutes + 1 min ground effect. When charging NiMH, I set the delta peak detection to Sensitive and disconnect immediately after full charge is reached (conventional wisdom is that NiMH don't like any kind of overcharging, including trickle charge). 

More recently still, I've started setting the charge current manually, to 700 mA, still with peak detection, this also works well. Interestingly, even on the manual setting, the Infinity still goes through a routine of ramping up the current from zero to 700 mA every couple of minutes, so even on the manual setting it appear to be doing some clever monitoring.

Fixing Things

The model is remarkably resistant to crashes, but inevitably things break or wear out. Different folks seem to have different things go wrong, here's a list of things that I've had to deal with. 

Landing Skid

My  landing gear struts tend to break at the base.  I use carbon tows to strengthen the joint. 

Get a few tows about 2" long, spot glue one end to the strut, wind the other end round the skid, and spot to the other side of the strut. Then apply cyano, wait to dry and cut off the excess carbon. 

Very effective. (I got the idea from another page, can't remember but thanks to the author anyway!).

Rotor Bearings

These tend to fly off all over the place and are difficult to find. I carefully cyano the bearings to the hub, this helps but occasionally the bearings slip off again, possibly because there's a film of oil on the inside of the bearings. I'd rather leave the oil on and put up with the occasional hassle.

Boom Attachment

Here's a mod which has saved me a lot of grief. 

Instead of gluing the boom to the main and tail rotor assemblies, I now rely solely on a friction fit. This has two major benefits (a) it allows the tail rotor assembly to twist in the event of a crash, absorbing some of the impact energy and reducing the risk of damage to the boom. (b) the boom can be replaced very quickly if necessary. 

Fixing Cracks in the Boom

Cracks in the boom are best fixed with slow-setting cyano, rubbed into the damaged area. I gave up using using low viscosity cyano, as it goes all over the place including the inside of the boom where it can end up playing havoc with the tail rotor motor power cable, or worse it can even dribble down the boom onto main rotor assembly, as I've discovered!

Tail Rotor Pinion

The plastic motor pinions tend to start slipping after a while. To prolong the period between re-gluing, roughen the shaft first with wet/dry paper. I use slow setting cyano to hold the pinion in place.

At Dortmund Ikarus were supplying replacements which had metal pinions, I bought one and have had no trouble. The problem will be transferring the pinion to another motor when this one wears out...

Removing a Brass Rotor Pinion

Thanks to Kris Manbeck for this tip: 

To remove the brass pinion for use on other motors, use a high powered soldering gun (about 100w), and a small vice. Put the motor in the vice snug. Next heat the (brass) gear with the soldering gun. While the gear is hot use a small pair of needle nose pliers or a small flat screw driver and simply pry it off of the shaft. Be carefull not to scar the teeth. If you use pliers try to stay on the hub of the gear. for install on the new motor. Freeze the new motor for a couple of hours (do not drop it after it is frozen the glue for the magnets gets brittle and the end bell is plastic they may crack on impact). Next heat the gear again with the soldering gun, after the motor is good and frozen! Hold the motor in hand or gloves. Do not use the vice. After the gear is hot lay it on something that will not melt! Face down (hub toward the motor) and press the motor on the gear. with the motor frozen (contracted) and the gear hot (expanded) they should slip together relatively easy. If it does not seem to work, do not pound the gear on! It may damage the brushes or end bell as they are delicate. Let the whole assembly set until cooled and thawed. ALSO be carefull not to push the gear on to far it will rub the motor can and  MAY cause the washers inside to chew up the brushes if it pulls the armature to far out. If the gear slips on too far, quickly pull it out until it is free of the motor can, keep your pliers handy while you attempt this.

Tail Rotor Motor

On one occasion I found the tail rotor motor did not appear to be working properly. I dismantled it and found that one of the windings had broken at a solder joint and had wedged itself between the armature and the magnet. The photo shows the damage. Note also the brush tracks on the commutator.

As an aside, disassembling the motor is easy, but putting it together again is another matter. The brushes are very delicate. If the end bell becomes separated from the armature you may as well toss the motor in the bin.