Trex 600E Pro Tail authority

[Granpappy]

I was just wondering if anyone knows if Align ever addressed the problem of low TR to MR ratio of 3.85:1. I've seen a Flybarred 600E Pro that I want to upgrade to an EFL head at a good price but I am now unsure.

I've read about problems with tail authority at normal head speeds unless you fit 105mm tail blades and 700 vert stab. This was back in 2011 on HF forum. It then transpires that the 105mm blades are loading up the umbrella gears too much which are then failing.

Did Align ever fix this or should I think about a Logo 600SX instead. Would prefer Align because it's cheaper to crash.

Cheers all.

[Grumpy]

No Align never addressed it, even the new 600L Dominator has the exact same design. However based on a couple of years flying my 600 Pro and making various modifications along the way I can make some suggestions and comments.

• Tail is ok if you only fly sports, it's only harder flying that will blow the tail out.
• Tail is ok for 3D if running high headspeed (2300RPM+)
• The bevel gear stripping problem occurs mainly when you use higher gov gain and/or have poor meshing. Meshing is fixed by using shims to take out gear slop, gov gain should be set in the 11-13 range in the Castle ESC.
• 105mm tail blades can hit the main blades if you fly hard! To use 105mm blades safely you either have to do a boom stretch or the ghetto/nasty solution; just slide the boom out of the mount by 5mm or so.
• Alternative to larger tail blades you can fit the older 600e auto and tail drive gears to increase tail RPM

I stripped the tail gears shortly after getting the 600 Pro but after lowering gov. gain and adjusting gear mesh it's been fine for hundreds of flights and those flights are with 105mm tails fitted. I did a 35mm boom stretch to allow the larger tails and also 623mm main blades to be used, this is a pretty easy mod using 700e parts (I can do a 'how to' guide if you like).

My stretched 600 pro is one of my favourite helis to fly, it's a real powerhouse with the Performance Booster kit and 700 class motor fitted (these are standard on the later 600 pro kits)

The only qualification I'll add is that I'm not a hard flyer. While my 600 pro has had hundreds of flights without any issue it's possible that a harder flyer might still expose problems.

[GIXERMAN]

105 tails on elf are ok without stretching

if you change to dfc then will need to stretch boom because of blade clearance with 105s

[Grumpy]

105 tails on elf are ok without stretching

if you change to dfc then will need to stretch boom because of blade clearance with 105s

I've seen photographic evidence of a main/tail blade strike on a 600 pro with the EFL head and 105mm tails. The guy in question had many safe flights before the blade strike so while it's probably ok 99% of the time the risk is still there.

[GIXERMAN]

ok, i had and flew one for 12 months without issue.

[Grumpy]

here's the post I was referring to with blade strike on the EFL head : HeliFreak - View Single Post - 600e Pro Tail Blow Outs

The evidence:


If you don't fly hard then probably it's fine, and even if you do fly hard it's probably fine 99+% of the time... but personally I'd not take the chance, small though the chance might be.

[GIXERMAN]

as i said previously i flew for 12 months with 600mm mains and 105 on a efl head with well maintained dampers

[Granpappy]

Many thanks for the useful information Gents. It's much appreciated.

Just one more question. Does anyone know if the Flybarred 600E Pro model has the latest mod umbrella gears (.8) I think, or does it have the earlier softer ones. I'm guessing that although the model is new in the shop, it must be pretty old stock and I don't know when the gears were modded. I think the originals were white and the later ones were black, but I can't be sure.

[Grumpy]

It will have the earlier white ones. the mod is the same, only the material changed between the early pros and the later ones. To be honest I'm not sure how much stronger the black gears are. It was black gears I stripped yet I had many flights on the white ones without problem.

The biggest difference between the EFL (along with earlier DFC models) and the later DFC and Dominator is the use of the beefed up 'Performance Booster' main-gear, pinion, motor mount and feathering shaft along with the larger 700 series 530kv motor.

The DFC models also have the dual arm tail control assembly.

[RcRotaryMadness]

Dont forget some tail strikes are caused by soft/worn dampers in the head rather than normal opperating clearences

[GIXERMAN]

Exactly as Post 7

[Grumpy]

Dont forget some tail strikes are caused by soft/worn dampers in the head rather than normal opperating clearences

Funny thing is that the guy whose blades are shown in post #6 was arguing the same point a few days before he had the blade to blade strike... "I've had hundreds of flights with no problem blah blah". (check the thread if you want)

The blades cant hit each other if they cant reach each other, regardless of what condition the dampers are in. So personally I'll go for the foolproof option of having the gap between the blades greater than the length of the blades themselves. Pretty much all helis come that way out of the box.

Don't forget that if the blades lead or lag slightly in the grips then with pitch they will angle down toward the tail blades, even with perfect dampers.


It's a fact that with 105 tails that you can by manipulating the blades by hand get them to touch... that for me isn't a good thing. Each to their own though, obviously the chance of a strike in flight is very slim.

[Granpappy]

Change of mind. I've just ordered the TT Titan X50E which I will kit out with Align electrics. It was a good price at Midland Heli's and they were very nice people to deal with. First time I ever bought anything from them and I think I will be back.