Question regarding head speed and tail authority

[Xrayted]

I'm in the middle of my EL Pro build after destroying my old T Rex 500. I understand the tail is geared differently on the Pro than my old belted model and requires a higher head speed (2800 or higher) to hold, and there is the current limitation with the 12T helical pinion being the max at this point.

I just discoverd my 1600 KV Scorpion motor was damaged in the crash and was thinking of trying the Viper 1800 KV. The reviews on this motor are mixed with some loving them and others claiming they run too hot, etc. Seems to be a lot of confusion as the proper electronic setup for optimal performance with them from the post I can find on them. Does anyone think going with a higher KV and the 12T would help getting the RPM up to where my CC 75 governor could be used on the Pro and the tail hold, or am I just asking for even shorter flight times with a higher KV motor than the already low Pro flight times?

[mhills51]

I put a 11t on mine. At first I had a leopard lc500 1720kv motor on it and it also ran hot. I now have the MX, but kept the 11t. I think the HS is about 3000

[tomd27858]

I am around 3000 as well with an 11t on a Scorpion 3226-1600. It is a perfect match at 100 flat throttle curves.

[Xrayted]

Ok, thanks guys. I will just stick with the tried and true Scorpion 1600. I like running governor on my helis, but I hear there isn't enough padding with this helis setup to get the RPM high enough and keep the CC ESC happy in governor mode. Looks like its back to fixed flat curves for this one.

When everyone talks about the tail kicking out at less than 2900 RPM, are we talking about during 3D moves or even in normal circuit flying? Would a simple pitch pump kick the tail out?

[Maypole]

Originally Posted by ICNU

When everyone talks about the tail kicking out at less than 2900 RPM, are we talking about during 3D moves or even in normal circuit flying? Would a simple pitch pump kick the tail out?

I'm currently running the 1600 on mine using 2600mah, 25c Gens Ace, 12t pinion, 12/12 collective/cyclic, and 95% flat. According to Mr Mel, this combo yields an average HS of just under 3100. The tail is rock solid during aggresive sport flying and hard pitch pumps don't phase it either. You can slam the collective all the way forward instantly from a hover just off the ground and be 100' up in about 1.5 seconds with no tail movement at all.

As far as hard, clean 3d goes, I really couldn't tell you. My meager attempts at 3d thus far have resulted in more of the soft and messy variety. I've seen similar setups to mine do some insane things though.

It's all about headspeed with this bird.

[Xrayted]

Originally Posted by Maypole

I'm currently running the 1600 on mine using 2600mah, 25c Gens Ace, 12t pinion, 12/12 collective/cyclic, and 95% flat. According to Mr Mel, this combo yields an average HS of just under 3100. The tail is rock solid during aggresive sport flying and hard pitch pumps don't phase it either. You can slam the collective all the way forward instantly from a hover just off the ground and be 100' up in about 1.5 seconds with no tail movement at all.

As far as hard, clean 3d goes, I really couldn't tell you. My meager attempts at 3d thus far have resulted in more of the soft and messy variety. I've seen similar setups to mine do some insane things though.

It's all about headspeed with this bird.

Thanks Mapole. I was only wondering because I'm strictly a sport flyer that likes flying large circuits with an occasional loop. I liked my old 500s 2700 RPM HS and 7-8 minute flight times and was just wondering if the need for the 2900 RPM+ would apply to my type of flying, or if I could get by a little lower and save some juice draw without tail issues.

I'm just going to have to get her finished up and in the air to see where my limits are, but it sounds like 2900 will be the minimum target with the different tail gearing.

[mhills51]

Some of the guy at the field suggested finding some wider tail blades.

[Xrayted]

Originally Posted by mhills51

Some of the guy at the field suggested finding some wider tail blades.

I have a set of the plastic Align blades that I used on my other model. They are a few mm longer and little wider chord wise at the root. I switched away from the FG Align blades because they caused much more vibration than the plastic blades did on my last build, despite every balancing trick I know. The plastic were smooth as silk.

[DesJardins]

Could toss on some Radix/EDGE tail blades

[Xrayted]

Originally Posted by DesJardins

Could toss on some Radix/EDGE tail blades

Yeah, Ive been looking a those as well.

[GT86]

Originally Posted by ICNU

I'm just going to have to get her finished up and in the air to see where my limits are, but it sounds like 2900 will be the minimum target with the different tail gearing.

You should be OK with that, but if you do anything that really loads up the head you may run into problems.

I normally run 100% flat with the 11 tooth and 500mx, but for curiosity's sake I was playing around at one point with headspeeds in the 2800-2900 range, and it was fine for the most part unless I got sloppy with the collective. I'd bog the head and get tail blow outs as the rpm dropped below 2800. It got to the point I could intentionally make the tail let go, especially after about halfway through a battery. The Castle logs indicated that headspeeds would briefly drop below 2800 during high pitch movements, and that's when I'd have problems.

I only had about 4 flights like this, my curiosity was satisfied pretty quick and I went back to a 100% flat curves. I had the stock tail blades on, so maybe bigger blades would have helped some. But given the severity of some of the blow outs, I doubt tail blades alone would have solved the problem.

[Xrayted]

Originally Posted by GT86

You should be OK with that, but if you do anything that really loads up the head you may run into problems.

I normally run 100% flat with the 11 tooth and 500mx, but for curiosity's sake I was playing around at one point with headspeeds in the 2800-2900 range, and it was fine for the most part unless I got sloppy with the collective. I'd bog the head and get tail blow outs as the rpm dropped below 2800. It got to the point I could intentionally make the tail let go, especially after about halfway through a battery. The Castle logs indicated that headspeeds would briefly drop below 2800 during high pitch movements, and that's when I'd have problems.

I only had about 4 flights like this, my curiosity was satisfied pretty quick and I went back to a 100% flat curves. I had the stock tail blades on, so maybe bigger blades would have helped some. But given the severity of some of the blow outs, I doubt tail blades alone would have solved the problem.

Great info! Looks like I'm in for shorter flights and little higher head speed than normal, even just cruising around with this one.
I will just have to give up my governor and run a flat curve as it seems to be the method of choice on this one.

[tomd27858]

An 11t pinion at 100 flat is the way to go on an EFL.

[GT86]

Originally Posted by tomd27858

An 11t pinion at 100 flat is the way to go on an EFL.

I agree. I put the 12 tooth back on earlier this week, I hadn't tried it on awhile and wanted to give it another try. Hotter batteries and shorter flight times for a marginal increase in performance. The 11 tooth is back on there now.

Sent from my tablet via Tapatalk

[Deet]

The SAB tail blades are the widest cord I can find for a 500

[Andy from Sandy]

If you run the 12 tooth pinion could you then run a governed headspeed? Wouldn't that yield a more consistant flight from start to finish?

If you run 100% flat isn't the headspeed going to start slowing after maybe the first minute until the end of the flight?

[mhills51]

I think what we are running into here is a over taxing of the motors. The gear ratio is too high for the scorpion and MX motors. I think the best combo here would be a scorpion 14?? than the MX or any 1600kv motor. The 450 size helicopters with newer motor tech 3800kv was the new normal, but when Align came out with the slant gears they had to lower that to the 3400kv. I think we are running into the same issue with the 500pro. It my thought is a powerful motor in the 1400 to 1500 would be ideal and allow the governors to work again.

[GT86]

Originally Posted by Andy from Sandy

If you run the 12 tooth pinion could you then run a governed headspeed?

No. The problem is the tail gearing is different from the ESP. Align designed it so that high headspeeds could be used. The best you can get at governed speeds isn't enough to hold the tail. You need a minimum of 2800 rpm for tail authority, closer to 2900 for consistency. The governor will get you about 2600 to 2700 on the 12 tooth.

Sent from my tablet via Tapatalk

[Andy from Sandy]

Using MrMels HS Calculator shows that with a 12T pinion the headspeed will start at 3377 and drop to 3000. How much headroom does your ESC need to run governed at 2800?

[Xrayted]

Personally, I think the only governor limitation seems to be the CC ESC. I ran the exact same setup on my prior FBL 500, which was the Scorpion 1600, slant gears and 12T pinion, but used a Hyperion ESC in governor mode instead of the CC. I had it set to auto motor timing, hobernor range 3 and it gave me 2850 RPM running a 38% flat curve in my DX8. I tached several HS using an optical tach dialing it in and it would have no trouble keeping the HS at in the 2900-3000+ range. I easily flew 7 minute circuits with this 2850 RPM setup, so I don't see any reason why I couldn't have locked it at 3000 and just cut my flight time down. Mind you I don't fly 3D, but my governor never bogged on me even in hard pitch pumps.

My electronics came down barely warm after flight, so it seems the limitation is with what the CC ESC wants to allow and not what the heli can actually do. I bought the CC for this heli for the data logging, but as of now I'm not so thrilled with what seems to be it deciding for me what my max governor settings will be despite me knowing what the heli can do.