RunRyder RC
WATCH
 1 page 342 views POST REPLY
HomeAircraftHelicopterLow Head Speed Helicopters › Headspeed and Throttle Efficiency
06-20-2018 01:23 AM  4 months agoPost 1
maxell44

rrNovice

Canada

My Posts: All  Forum  Topic

Hi guys I didn't know of anywhere else to post this but here, as its all about headspeed in general. I googled but didn't find a diffinitive answer.

Ok here I go. I recently, over the last few months (since febuary last year), converted a Raptor 50 Titan to electric. CNC parts just added in the last month not pictured.

https://rc.runryder.com/t824088p1/

Its been flying fine even after all the Quick UK upgrades I've done to it. That said, I just threw on the Thunder Tiger CF Blades (black and white ones), I got with it. They are wider cord blades, the other ones that also came with the Heli were CF, black, and narrow cord and a no name brand as far as I can see. So I plugged in the #'s and came to realize that there is only a 117 rpm difference between 90% throttle and 85% throttle as per my flight testing with the wider cord blades.. At 90% throttle @ 2092 rpm the motor and ESC are hot but not to hot I can't touch them for some time. At 85% throttle @ 1975 rpm the motor is a little hotter and the ESC is a little hotter. I can still touch them as well and keep my fingers on them. So my question is which is the better efficiency 90% or 85% throttle. I might mention I fly with a flat throttle curve and only use pitch to fly. Battery IR's are the same: 3.82 to 3.83 v's per cell at 6min flights. **Batterys are not warm after flying**

Here are the #'s:

Motor: 890kv
Battery: 22.2 6s 5000mah 40c
ESC: Talon 90amp
Pin gear: 10
Main gear: 85
Ratio: 8:5
Blades: Thunder Tiger CF wide cord 600mm
Weight: 8.26 lbs

Formulas I used:

Motor kv * volts * pinion / maingear.

1. main gear / teeth of pinion= main gear ratio
2. motor kv* battery voltage= motor rpm
3. motor rpm / main gear ratio=headspeed

(battery_voltage * kV) / (main_gear/pinion) * efficiency

Any suggestions greatly appreciated.

PM  EMAIL  GALLERY  Attn:RR  Quote
06-20-2018 02:46 AM  4 months agoPost 2
Pistol Pete

rrProfessor

Seffner, FL

My Posts: All  Forum  Topic

Brushless motors and ESC are most efficient at highest numbers.

A "little hotter" at 85% doesn't actually mean much unless it's actually measured to get real temp numbers in order to determine if you are anywhere near max temps (doubtful). Your tolerance to heat may differ from mine given skin thickness. Five seconds is the average a person can tolerate up to 140°F before feeling the burning pain. Consider getting an inexpensive temp gauge.

Your ESC also has settings that affect performance and temperatures such as PWM and timing. Consider posting them. Your motor may have a recommended timing but in general, motor runs cooler at lower settings.

PWM Formula
3.7V per cell x Kv x pole count / 20 = ?Khz.

If you prefer the lower head speed, consider changing the motor pinion size in order to run motor and esc at higher settings for best efficiency.

You will find a happy medium eventually.

~~Enjoying the hobby one flight at a time~~

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
06-20-2018 03:41 AM  4 months agoPost 3
turboomni

rrProfessor

East of the Equator

My Posts: All  Forum  Topic

There doesn't seem to be any mention of how much pitch you are running which could mean everything.

Setup is everything, All my heli's can fly far better than I can pilot them

PM  EMAIL  GALLERY  Attn:RR  Quote
06-20-2018 12:44 PM  4 months agoPost 4
Dr.Ben

rrMaster

Richmond, VA, USA

My Posts: All  Forum  Topic

Highest throttle % for chosen rpm with just enough left for headroom is best. Speed controls with active free wheeling like Kontronik and YGE tolerate lower percentages with less heat build up than passive free wheeling controllers like the Talon.

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

PM  EMAIL  GALLERY  Attn:RR  Quote
06-20-2018 02:24 PM  4 months agoPost 5
gwright

rrVeteran

Champaign Il

My Posts: All  Forum  Topic

Drop a tooth in pinion to get to the lower rpm if that's where you want to fly. Higher throttle percentage,.. everything cooler, current spikes with full pitch will be much less. I know the rpm change doesn't sound like much but power requirements go up exponentially with rpm increase,.. for example, 2100 requires 14% more power than 2000, actually , although it's only a roughly 5% difference in rpms. you may notice a 5% difference in throttle, but that's sort of irrelevant as throttle percentage doesn't equate to output power directly.

As it's overgeared for the lower rpms, of course throttle is lower, and overall power required is lower, but when you hit lots of collective, or cyclic, you're actually loading it more (higher current spikes) than you would at the higher rpms. i've logged data and looked at graphs many many times over the years, and i like to gear as deeply as possible, while still retaining enough headroom at the highest throttle setting,.. which is usually 96~100% for the way I normally fly. If you want to really pull hard in bursts like smack flying, this doesn't work well,.. you need a lot more headroom, but for slow/smooth 3D it's very efficient to have KV/gearing/voltage optimized to use the highest throttle percentage.

Gary Wright

PM  EMAIL  GALLERY  Attn:RR  Quote
06-20-2018 07:30 PM  4 months agoPost 6
Heli Fanatix

rrVeteran

Fountain Valley, CA

My Posts: All  Forum  Topic

Very well asked with good details, here is our suggestion:

Get a non IR Temp Gun
- measure the same spot every time
- we don't use the finger method just like some of us in life with the crossed "finger method" and hope things get better.
- everything starts with learning, applying til we hit our goal.

ESC
- as you can tell, you ESC is happy @ 90% so stick to it
- we can only tell you about what you got for now to keep it simple

Blades
- Wider Cord blades grab more air b/c of its solidity
- It's recommended to drop 2-3 degrees

When you get your IR Temp Gun
- Do each change one at a time
- Take temp readings before and after
- Let us know

PM  EMAIL  GALLERY  Attn:RR  Quote
06-20-2018 10:00 PM  4 months agoPost 7
maxell44

rrNovice

Canada

My Posts: All  Forum  Topic

WoW, you guys are way more technical than me. But thats a good thing. That said, "Yes", 90% has been the sweet spot thru-out this whole project. As some of you have suggested changing the pin gear is not an option. As per the conversions forum and the 17 page thread I read, your basically stuck with the stock gearing, 10 pin and 85 main. Sure you could put the Raptor 30 gearing in 9 pin and 86 main but that would constitue a complete tear down of the Heli. The motor mounting plate has to have the frame halfs seperated to be installed. Not something I'm willing to do, especially after installing all that CF and CNC stuff. However, today after work I flew 3 batterys with the following pitch curve, which I might ad was the way the previous owner had it set to but I (in my infinite wisdom...duh),decided to read online about various curves (which I shouldn't have), and played around with different pitch curves. It seems this curve: 31.5,51.5,71.5,84,94.5 (previous owner), with my 90% flat throttle curve works excellent with the wider cord blades. (BTW those wider cord blades were on the Heli when I bought it). Now, It has never felt so locked in and solid since putting those blades back on (which I should have not even have taken off in the first place). The motor and ESC are now cooler than they were after running 6 mins the other day when I first posted here. My only concern has been over running the batterys and over heating the ESC. So as I said just a moment ago, everything is cooler. Just a change in pitch curve made a world of difference. I can't beleive it, how could I be so dumb and stray away from how the previous owner had it set up right in the first place. Obviously he knew what he was doing as he built it and I did not. *sigh* Thank you guys for your advice and knowledge. I have saved bits and pieces from it. You guys are awesome and very knowledgable.

PM  EMAIL  GALLERY  Attn:RR  Quote
06-21-2018 02:49 PM  4 months agoPost 8
gwright

rrVeteran

Champaign Il

My Posts: All  Forum  Topic

Lower KV motor is the real solution since your gearing can't be adjusted. I currently run an 890kv motor on 6s with 606 blades (stretched E5). I'm using a 12 tooth pinion and 121 tooth main gear. (890*22.2*12)/121=1959 possible. That's been confirmed with non-governed mode in the ESC at full throttle and neutral pitch. Actually it will spin a bit higher than that. I fly modes of 1900 and 1500 on that machine, and sometimes fly 5S at 1300/1500 (really really sweet with 5s). i wish I had a lower KV motor but don't. You could always try a 5s pack instead of 6s.

by comparison, you're config is (890*22.2*10)/85, equaling 2324. it obviously works, but I would call it massively overgeared. Dropping to 5S packs you'd calculate to 1937 max, so you should be able to govern to 1900,.. although with the low voltage you may need more headroom, so 1850ish would be my guess for proper governing. However, that high of an rpm on only 5s is still going to be pretty innefficient. probably an improvement but not a huge one.

Gary Wright

PM  EMAIL  GALLERY  Attn:RR  Quote
06-21-2018 11:10 PM  4 months agoPost 9
maxell44

rrNovice

Canada

My Posts: All  Forum  Topic

I understand what your saying, but changing the motor in this thing is no easy task. In fact, I have thought about putting a 1100kv motor in it. Same motor as the ERaptor 550. But I just can't get past that tear the Heli all apart thing just to change the motor. I never thought of it as over geared but you know better than I. The "Heli's" comfort zone seems to be that 90% throttle. It gives me the aggressivness (aggressive sport flying), I'm wanting out of it mixed with the docile tendencies to fly in a slow scale manner. Its basically a trade off between stability, power and speed while having enough headspeed to be completely managable and feel locked in like it is. It seems to like that 90% sweet spot. I swear this thing has a mind of its own. Its alive. lol. I'll leave it as is and say for the record the project is finally completed. I'm proud of myself after seeing it fly the way it does and what I went through during the whole process. A true feeling of accomplishment. If the heli is happy then I'm happy.

*note those pictures were taken before I re-installed the Thunder Tiger wide cord blades*

PM  EMAIL  GALLERY  Attn:RR  Quote
06-27-2018 03:56 PM  4 months agoPost 10
Richardmid1

rrProfessor

Leeds, England

My Posts: All  Forum  Topic

gwright
You could always try a 5s pack instead of 6s
This is what I would do. No other change needed, just run 5s instead of 6s.

It also means you can run larger capacity packs for the same weight (6s 5000mah vs. 5s 6000mah), this will give you even more flight time. You would simply run it at 100% throttle which would give you 1950-2050rpm on your setup.

60% of the time, it works every time!

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
07-01-2018 06:08 PM  4 months agoPost 11
maxell44

rrNovice

Canada

My Posts: All  Forum  Topic

How come I never thought of that...? Everything would run cooler correct...? Less weight I'd imagine as well. Hmm, longer run time you say...I'm gonna seriously look into this option. Sounds like a solid idea. Thank you for this.

PM  EMAIL  GALLERY  Attn:RR  Quote
07-02-2018 02:19 PM  4 months agoPost 12
Richardmid1

rrProfessor

Leeds, England

My Posts: All  Forum  Topic

Yes it would run cooler and yes if you ran only 5000mah 5s packs it would be lighter.

60% of the time, it works every time!

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
WATCH
 1 page 342 views POST REPLY
HomeAircraftHelicopterLow Head Speed Helicopters › Headspeed and Throttle Efficiency
 Print TOPIC  Make Suggestion 

 7  Topic Subscribe

Tuesday, November 13 - 1:07 am - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

The RC discussion world needs to consolidate. RR is now one choice for that. Its software is cutting edge. It hosts on-topic advertising. Help RR increase traffic buy making suggestions, posting in RR's new areas (sites) and by spreading the word.

The RunRyder Difference

• Category system to allow Rep/Vendor postings.
• Classifieds with sold (hidden) category.
• Classifieds with separate view new.
• Answer PMs offsite via email reply.
• Member gallery photos with advanced scripting.
• Gallery photo viewer integrated into postings.
• Highly refined search with advanced back end.
• Hosts its own high end fast response servers.
• Hosts thousands of HD event coverage videos.
• Rewrote entire code base with latest technology.
• No off-topic (annoying) click bait advertising.
Login Here
 New Subscriptions 
 Buddies Online