Another E5s tail ratio question

[Thunder Fighter]

Hi guys,

I picked up a new E5 kit to build up as my next Heli as well as the parts to stretch it for 626 blades. I am pulling the gear out of my Logo 600 and was planning on running similar headspeeds that I had on it (1650/1950/2150rpm with 600mm blades) as a starting point. I do smooth 3d and will be setting this up as my F3N competitions machine and I am thinking that the extra blade length will make up for the slightly higher weight of the airframe.

I have read up on the available tail ratios and the recommendation from Matt on the tail speed so I am planning on running the 4.9 ratio with 96mm tails, which will give me optimum tail speed at 1950rpm where I will do most of my manouvers and still not stupidly high in IU2.

But I was also thinking the other way of achieving the tail hold would be to go to the 4.5 ratio with 116 blades. So my couple of questions are:

Will the 116mm tails fit the E5s running 626mm mains?
Has anyone tried these two different setups and can comment on which gave a better tail?

My other equipment will be:
Motor: HKIII 4035-560
ESC: Hawk 120A, Vbar gov
Batteries: 10s 4000mah
FBL: full size Vbar
Servos: TBA (the old sevrvos from my logo are in need of replacement after 4 years of service)
Power system: 2s Lipo or Life depending on servos
Rail 626 mains and Rail 96 tails
14t pinion should get me close to 2150rpm but I might have to go to the 15t if there is not enough overhead.

//Dennis.

[Josh Moen]

Hi Dennis,

 On my 600 e5 stretch I'm running the same motor on 12s with a 12t pinion at 1750 in normal, 2100 in idle-up 1 and 2250 in idle-up 2. After a week of flying it I was having some issues with the tail holding during demanding maneuvers. I installed I installed the 4.9 ratio and it was much better but I could still get it to blow out at times. Ive now got some 106s installed and that solved the problem. I am going to add that I live in Denver, CO and fly around 6000' asl so my experiences may differ slightly. I also have been flying this heli is 606s and have not flown the 626. Another flyer out here just did a 600 stretch with his and he is flying 626s and 106s with not issues. The 116s would probably be fine with your flying style but I'd be cautious. On another note the 116s are real close to the ground with the stock tail fin so if you decide to go with the 116s I would get the N7 tail fin which is longer to accommodate date the 116s and will bolt right on.

Let me know if there is anything I can do to help!

Here is the gear I used in my E5 stretch:
Scorpion HKIII 4035-560
12t pinion
606 Rail main blades
106 Rail tail blades
4.9 tail ratio
Castle 120hv
Currently flying the CGY 750 was flying the iKon

[Thunder Fighter]

Thanks Josh, that is great information. The 106mm tails are out of stock at the moment out here and that is why I was looking at the 116's. I will give it a try with the 96's and the 4.9 ratio to start with and if I have issues I can jump up to the 106's when they get more in. I'm nearly at sea level so I will have more bite here.

I was running 104mm on my logo which has a 4.66 tail ratio so it sounds like I am in the right ballpark.

I notice that there is a hardened version of the 11t tail drive gear. I am guessing the kit version is not hardened or have the kits been updated? Is the hard coated gear a recommended upgrade?

//Dennis.

[Josh Moen]

I'm pretty sure that all of the tail spur gears are hard coated. If they aren't, it would be news to me.

[Josh Moen]

I stand corrected. The original spur gears were not hard coated and were almost a shiny black. The e5 kit you have most likely has a hard coat spur gear. Sorry for the correction.

[Thunder Fighter]

No problem, I saw some of the early ones on the wall at the shop and wasn't sure if it was an option or if they were older stock. I didn't realise the stock one was a 13t, I thought there were only 11 and 12 tooth versions. I will need to get an 11t for my 4.9:1 ratio anyway and I will make sure it is the hardened one.

//Dennis.

[Rob Cherry]

All 11t spurs are hardened, they were introduced at the beginning of the hard coat change over. Order one up!