T-Rex 500 Torque Tube

Written by Ashley Davis Tuesday, 30 September 2008 00:00

Torque Tube

The torque tube upgrade has been available for a while on the T-Rex 500 and I felt it was probably time I took a look to see what difference this makes to the 500. I'll happily state upfront that I've had no issue with the belt drive aside from the nightmare static issues that hit some T-Rex 500. Having solved all my static issues the torque tube brings promise of a crisper tail response and potentially better autorotation due to less drag in the gear system than the belt drive.

So, upon opening the upgrade kit you are greeted with the torque tube itself, the new boom clamp, tail gearbox (lightly pre-assembled) a parts bag and the bearing for the torque tube. Assembly is extremely staright forward so I won't dwell on it other than to add a tip on getting the torque tube inside the boom. I use silicone grease on the inside of the boom to allow the rubber bearing holder to slip down the boom easily. Parts quality is very nice, take care that the tail gearbox is just lightly preassembled and all the relative nuts and bolts will need tightening and loctite applied. The torque tube itself has a smaller mod of gears than that used on the 600. Crucially it also appears to have more teeth engaged at any one time, which spreads the load across several teeth at a time. This is something the T-Rex 600 tail doesn't do well. Whether this tail proves to withstand long grass landings or abusive tail scrapes at the ends of autos or bad landings remains to be seen. I've yet to strip my gears but due to the atrocious UK weather this summer I've not really had a huge number of flights on it to test durability.

OK, so lifting off the first flight some differences were noted. Firstly the tail is definitely a little more crisp with less tendency for a soft stop. Outside of this tail hold was very similar and I still got the odd tail wag in heavly loaded situations. So powered flight the only gain is a mildly crisper tail response, never-the-less I'll take that rather than not have it at all.

What about autorotation? Well there has been much hype about better autos and hang time etc etc. To test this I flew two 500s back to back performing autos. Personally I really couldn't tell much difference, sometimes the belt 500 seemed to auto better, other times the torque tube driven one. My only conclusion being that belt drag on the 500 is less of a significant factor than the overall inertia in the blades.

Pros

Slightly crisper tail on piro stops
Relatively easy upgrade
Permanent fix to boom/belt static issues
Nice quality parts

Cons

Not the cheapest of Align upgrades
Potential for durability issues similar to the 600 on stripping the torque tube gears

Conclusion

The 500 torque tube isn't a hugely cheap upgrade and for me gave little in terms of performance gains over a belt drive T-Rex 500. It does look very bling and therefore qualifies as a pretty upgrade for those who are 'heli proud'. Gear durability being my main concern for long term ownership. For those with belt static issues that don't seem to want to go away this is a must have upgrade as it fixes the boom static problem very nicely. Overall it's a nice conversion, installs easily and does offer a performance gain over belt, on the downside it's quite expensive as an upgrade when you consider it doesn't offer a huge amount in performance gains.

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