(02-11-2026, 12:42 AM)Homer Bell Wrote: The belts with the proper numbers specified 20 in a box on the belt, have been working just fine for over 30 years. I think it would be foolhardy to go off looking for a different belt. The long length of the belts we use , makes the very small twist negligible and has proven to be no problem at all.
This continual search for fixes for problems that don’t exist is dangerous. I certainly hope that you didn’t tell the belt supplier that we were using these on a helicopter. Next thing will be that supplier will quit selling us these belts that we’ve been running since 1995. We’ve tested them LONG ENOUGH!!! They work fine!!
Hi Homer, I cannot agree with you. A simple google search re RW and tail rotor belt failures brings up significant reported failures for whatever reason, along with the observations that most are not reported so Google cannot find them.
This problem has been blamed on lack of maintenance so many times even I began to believe it, but the truth is the wrong belt has been used from day one, CASA are looking into it here in Australia, but being an Experimental Amateur built helicopter, to a large degree their hands are tied, but they have said they will investigate as this has been reported numerous times here in Australia. To make the problem more complex, people who have bought a RW or have had someone build it for them sign a liability waiver that says they built it thus can maintain it, sadly that has been the death of one person and numerous other accidents.
One of your catchphrases has been "if it ain't broken, dont fix it". I just wonder, when you had that broken frame that impacted the collective, if RW had stood back and said we didn't need to add a couple of gussets to stop that ever happening again - what would have happened to RW then? However, they did do the right thing and came up with a solution that we all benefit from today.
Why didn't RW also do the same due diligence on failed tail rotor belts? I am guessing that information was not readily available and the belt at the time was not approved by the manufacturer, so it remained a maintenance issue. RW at the time sanded off the manufacturers brand name that was on the Vee belt.
Information today is everywhere and a simple search and talking to belt suppliers about Vee belts and the HP RPM and Twist are easily answered.
Here is some of that information....
Running a standard V-belt—which is designed for straight, non-twisted alignment—with a 30-degree twist is a bad idea that will lead to rapid, severe, and permanent damage.
Because V-belts are designed to run in a straight line, introducing a 30-degree twist puts enormous unnatural stress on the internal tensile cords.
Here is what will happen, ranked from immediate to long-term:
1. Instant Effects (Running)
Excessive Heat Generation: The rubber will distort and twist, creating internal friction that generates high heat. This heat softens the rubber, often leading to a distinct burning smell and smoke.
Irregular Tracking: The belt will not sit properly in the sheaves (grooves) of the pulleys. It will likely try to climb the sides of the pulleys.
Extreme Vibration: Due to uneven tension across its width, the belt will vibrate violently, leading to noise.
2. Immediate Damage (After a few minutes/hours)
Permanent Distortion ("Set"): The belt will lose its cross-sectional shape and develop a "memory" of the twist. Even if you correct the misalignment, the belt will likely continue to want to roll over.
Internal Cord Damage: The tensile cords (the strength backbone of the belt) will be overstretched on the outside edge and buckled on the inside. This breaks the cord-to-rubber bond.
Rapid Side-Wall Wear: The sides of the V-belt will wear down extremely fast due to friction against the pulley sides, often leading to fraying.
3. Final Result
Premature Failure: The belt will fail, snap, or tear itself apart far sooner than its rated lifespan (often within hours, or even minutes, depending on load).
Risk to Equipment: The high vibration and heat can damage bearings, pulleys, and shafts in the drive system.
Summary
Don't do it. A 30-degree twist is far beyond the allowable angular misalignment (usually less than 0.5 degrees). If you must have a 90-degree turn in your system, you cannot use a single, standard rubber V-belt. You must either align the pulleys properly, use multiple pulleys, or use specialized equipment like gearboxes or right-angle drives.
Even RW themselves took on board the TR belt issue and came out with the Talon with gearboxes, and straight drive vee belts driving the first gearbox. One wonders why it took so long to find a solution...
But more good news is they do make belts today that will take a 30 degree twist, not stretch, and will transmit the HP needed (approx 15HP).
Why would you be against that, when the solution is only $150 for 3 belts and 2 hours work????
'Continuous improvement is better than delayed perfection' and innovation is only found when we always aim to improve - even when it's "not broken".
For a 3V V-belt application requiring a 30° twist, the best options are, in order of preference, linked V-belts, raw-edge cogged, or highly flexible wrapped belts, as these allow for easier twisting without damaging the belt or overloading the pulleys
