RunRyder RC
 9  Topic Subscribe
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 3783 views
Scorpion Power Scorpion Power
HelicopterScale Model RC Helicopters › Scale head speeds
02-03-2017 11:01 PM  9 months agoPost 1
Tim W

rrNovice

Rancho Cucamonga​California

My Posts: All  Forum  Topic

Okay, I am trying to see what would be the best head speed for scale flying and longer flight times. I'm currently flying a 700 size Bell 429 by Roban Models. My head speed now is 1325 and my heli flys fine. Keep in mind this has a four blade head. I was told by another chopper pilot who flys a similar bird, that if you increase the head speed you'll need less pitch, and in turn will keep the amp draw low and give you longer flight times. In a way this sounds logical, but just want to see what other folks have to say?

PM  EMAIL  GALLERY  Attn:RR  Quote
02-03-2017 11:53 PM  9 months agoPost 2
coptercptn

rrElite Veteran

Mesa AZ. USA

My Posts: All  Forum  Topic

Every Heli has sweet spot.. experiment with pitch and head speed to see what suits your Heli/flying style...there is no "cast in stone"settings that work on every bird....
And yes, as a rule higher speed will require less pitch.

Home of the "Sea Cobra".....

PM  EMAIL  GALLERY  Attn:RR  Quote
02-04-2017 12:00 AM  9 months agoPost 3
Tim W

rrNovice

Rancho Cucamonga​California

My Posts: All  Forum  Topic

Okay, so theoretically if I increase the head speed which in turn reduces the pitch needed for lift, then I should draw less amps. And in turn get longer flight times (hopefully)

PM  EMAIL  GALLERY  Attn:RR  Quote
02-04-2017 12:53 AM  9 months agoPost 4
Copter Doctor

rrProfessor

Enterprise/ft.rucker​,al- home of army​aviation

My Posts: All  Forum  Topic

for me, scale headspeeds mean what looks right. if I am doing a huey or bell 212 I am going for a low looking rotor speed. if I am doing an md 500 or an airwolf or so, then I am gonna do a higher headspeed. Whatever setup it takes to get those is what I shoot for.

drive a rotary, fly a rotorcraft

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
02-04-2017 01:04 AM  9 months agoPost 5
ssmith512

rrKey Veteran

Indianapolis, IN USA

My Posts: All  Forum  Topic

Lower head speeds (assuming the model is geared properly) will always result in longer flight times. As you increase rotor speed, drag goes up dramatically (I think drag is proportional to the square of velocity). As drag goes up, so does current. Increasing pitch will also increase current, but reducing rotor speed will reduce current by a more significant amount.

Gary Wright (maybe the undisputed king of low rpm flying) has been doing low speed flying for a LONG time. Here is what he says about it......

I've been through this , several years ago actually. I still watch and record data, and lower rpms with more pitch will give you much higher flight times,..however,..if you're one of those that likes "pop" then you'll lose it with the lower rpms. Dropping just a little rpms drastically reduces the current (both average and peaks), while increasing pitch increases both, but not a huge amount. I fly a wide range of rpms on most of my setups so I can share some data for you to consider. On my current favorite machine,.. which is an 800, flying on 12S, I have three flight modes setup, 1100,1400,1600. I know 1600 doesn't sound like a lot but gpms telemetry has shown 106mph downwind (probably 90~95 in reality due to wind), and that's certainly not slow or underpowered. In 1100 it will do very smooth 3D for a long time.I have telemetry and logging on it, so I do know the real numbers, so to speak <G>. In 1100 mode with 16 degrees pitch the peaks are right at 30 amps, hover upright and inverted in the 9 to 10 amp range, very smooth 3D for 20 minutes. In the 1600 mode(only 12 degrees of pitch)there's a lot more "pop" of course with the tip speeds equivalent to a 700 at what most consider "normal rpms" Current peaks in the high 90's (just over triple the 1100 mode), average current in the mid 30's, flight times to 4000mah telemetry alarm are 6 to 8 minutes.
I also made spreadsheet including a formula used for power requirements at various rpms for turbines and it's amazingly accurate for predicting increase/decrease in energy usage for our helis. One perfect example is one of my 700's that I love to fly in 1300rpm mode. I generally go 10 to 12.5 minutes on that one in just the low rpm mode, using 12S/5000(lots of pitch in that setup also). This is flying untill a capacity alarm tells me 4000mah used. A certain top name pilot from the netherlands flies that machine with 12S/5000's at 2350. Yes, his flights are really fun to watch!, but he flies 2.5 minutes. Same energy usage, 5 times the flight time with 1300 as 2350. Spreadsheet tells me his rpm should require 4.7 times the power that my lower rpm setup requires. 4.7,... 5,... pretty good prediction, the difference I would account to his smack style flying (higher peak currents and more of them)

As has been stated, find the head speed that works for you and your heli, but lower headspeeds are better for flight times than higher headspeeds.

Steve

PM  EMAIL  GALLERY  Attn:RR  Quote
02-04-2017 02:06 AM  9 months agoPost 6
oldfart

rrProfessor

Vancouver, Canada

My Posts: All  Forum  Topic

I have found the same as Gary as stated above. It also is true (relative to fuel burn) for nito and gasser helis.

Phil

PM  EMAIL  GALLERY  Attn:RR  Quote
02-04-2017 08:36 AM  9 months agoPost 7
Andy01

rrApprentice

Brisbane, Australia

My Posts: All  Forum  Topic

IMO 1325rpm is a fair bit too fast for a 4 blade 700.

My 2x 710mm Long Ranger runs well at 1350rpm, as does my 4x 600mm Seahawk. My 4x 820mm EC-145 runs at 1050rpm and has plenty of lift.

My guess is that around 1150-1200rpm would be a decent starting point.

And yes, slower headspeeds ALWAYS result in longer flights due to the power being affected by velocity² (as said above). So although your pitch is less, the drag on the blades increases because it takes a lot more power to push them through the air faster.

A good rule of thumb for a 2 blade heli flown in a smooth scale-like way is 50W/lb of weight, and a 4 blade might be around 55-60W/lb, so if your heli weighs say 20lbs, then you should be drawing around 1100W in FF, which on 12s is around 25A.

Colin

Vario Long Ranger 700e
Seahawk 600
UH-1N 500
Baumann EC-145 800+ (coming soon )

PM  EMAIL  GALLERY  Attn:RR  Quote
02-04-2017 04:43 PM  9 months agoPost 8
doorman

rrProfessor

Sherwood, Arkansas

My Posts: All  Forum  Topic

700 Size Roban

I just finished up an RC Aerodyne (Roban) AS 350 with 4 blade head...
I set my HS at 1330 and all is good, but the tail is weak.. At 1350 the tail gets better..the stock tail blades that came with the kit are 100mm..
To combat the weak tail, I am trying 105 tail blades at 1330..and I can go up to 113 mm without interference... I like the 1330 HS and am working to keep it.. My average amp draw during the first few hops is about 25 amps or 1175 watts...
If the longer tail blades will let me, I will drop down lower on the HS.. I would like it better at 1250, but not sure this will happen with the stock blades.. 44mm chord..

As Jim mentioned, every heli has a "HAPPY PLACE"

Stan

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

PM  EMAIL  GALLERY  Attn:RR  Quote
02-06-2017 12:30 AM  9 months agoPost 9
Copter Doctor

rrProfessor

Enterprise/ft.rucker​,al- home of army​aviation

My Posts: All  Forum  Topic

Stan, you have s 4 bladed head on your Astar?

drive a rotary, fly a rotorcraft

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
02-06-2017 12:30 AM  9 months agoPost 10
Copter Doctor

rrProfessor

Enterprise/ft.rucker​,al- home of army​aviation

My Posts: All  Forum  Topic

Had to be a typo I have my Astar st a moderate head speed with blades I made to compensate for any yaw control loss

drive a rotary, fly a rotorcraft

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
02-06-2017 02:53 PM  9 months agoPost 11
doorman

rrProfessor

Sherwood, Arkansas

My Posts: All  Forum  Topic

OOOOP's

Nice catch Emile
Mine is 3 also... I am beginning another project that will be a 4 blade... guess I was thinking of that one

Stan

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

PM  EMAIL  GALLERY  Attn:RR  Quote
02-06-2017 02:55 PM  9 months agoPost 12
doorman

rrProfessor

Sherwood, Arkansas

My Posts: All  Forum  Topic

Blades...

OK Copter Doctor,
You got my attention.. tell/show us your blades!!! (please!! )

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

PM  EMAIL  GALLERY  Attn:RR  Quote
02-06-2017 04:55 PM  9 months agoPost 13
Tim W

rrNovice

Rancho Cucamonga​California

My Posts: All  Forum  Topic

Okay so over the weekend I was able to test and see if by lowering the head speed on my Bell 429 would give me longer flight times. So just a quick recap on my original head speed. I was running at 1300 rpm and I am on 12s 5000mah batteries. After 5 minutes of scale flying my voltage per cell comes in at 3.82/3.85 per cell. Now I lowered my head speed to 1200 a 1000 rpms lower than I originally had it set at. Now after the same flight time of 5 minutes to my amazement I didn't notice any voltage difference per cell after I was finished. I flew the same scale pattern so now I am scratching my head????

PM  EMAIL  GALLERY  Attn:RR  Quote
02-06-2017 05:17 PM  9 months agoPost 14
gwright

rrVeteran

Champaign Il

My Posts: All  Forum  Topic

That change in rpm should net you around 14% to 16% increase in flight time. However, checking voltage is not a great way to see how much you used out of the pack. It's a secondary indicator at best, and when a pack discharges, it is not a linear drop from 4.2 to 0. It will drop into the mid 3.8's, or 3.9's and flatten out, stay there a long time, then drop more. I use telemetry with capacity utilization, but you can also just recharge and see how much you put back in. I really love capacity telemetry, as I can be exact in battery usage, no matter the rpm or style of flying on a particular flight. I've always equated using voltage to determine battery usage as similar to checking the octane rating in gas and trying to determine how much is in the tank It is very good to set a minimum discharge threshold so as to keep the cells healthy, but equating voltage to capacity isn't very accurate. It's a bit like the fuel guage on a general aviation airplane. According to the FAA they only have to be accurate at full and empty. If your battery is at 4.2, or actually 4.23,..then it's full. If it's at zero then it's empty Other than that,. the voltages in between are indicative of the state of charge, but they aren't very accurate if you want to associate voltage and capacity utilization.

Gary Wright

PM  EMAIL  GALLERY  Attn:RR  Quote
02-06-2017 05:37 PM  9 months agoPost 15
TailKiller

rrApprentice

Panama City, FL

My Posts: All  Forum  Topic

You have a 13.8:1 gear ratio in that heli as do most of us with SS helis. I has a 22t motor pulley. Raising the motor pulley tooth count will reduce the ratio and along with the lower rpm should give you a little better flight time but I wouldn't expect a extra 5 minutes. You have more flight time in reserve now. Coming down with 3.85 per cell after 5 mins leaves additional flight time unused. Set your timer for 6 mins and see the per cell voltage. If your batteries are good you should have no issues. Keep in mind that this may rause your ESC temp.

,Dennis
http://pcrcheliclub.com/
700 Astar Super Scale T-600 Bell 206 Trex 600 Naza H DX8

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
02-06-2017 06:45 PM  9 months agoPost 16
doorman

rrProfessor

Sherwood, Arkansas

My Posts: All  Forum  Topic

ESC TEMP??

I was just reading your post and on 12s lowering your HS to 1200 or even lower may kill your ESC.. which are you using?? Have you checked temp on the ESC, motor, and batteries running that low?
Very important...
If you want to go down that far, you might want to change your battery count, from 12s down to 10s or even 8s maybe..
I did a test yesterday on a rex 500 that runs normally on a 6s 3000.. lowest HS per my ESC settings 1950 6:00
Without making any changes, except for the battery I installed a 5s 3000.. lowest HS per ESC settings 1700 6:00
Then one more time I loaded a 4s 3000 for a low HS of 1550 and ran for 6:00
Each time the batteries were coming in at 50-55% left in the pack.. so on 4s I have set my timer to 7:00 and plan to use the 4s set up... the only change I will make will be to set the ESC (Castle Creations Edge Lite 75) for the 4s configuration..

Stan

I think he might have just hear at least three different ways to check your batteries.. I check with a meter that gives me a % left in the pack and can check each cell in the pack... I always set up to leave 20% in at the end of a flight and that is generally about 3.75 per cell...

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

PM  EMAIL  GALLERY  Attn:RR  Quote
02-06-2017 07:08 PM  9 months agoPost 17
Tim W

rrNovice

Rancho Cucamonga​California

My Posts: All  Forum  Topic

Doorman, my ESC is a Castle Creations 120 amp HV.

PM  EMAIL  GALLERY  Attn:RR  Quote
02-06-2017 07:17 PM  9 months agoPost 18
doorman

rrProfessor

Sherwood, Arkansas

My Posts: All  Forum  Topic

CC 120

Hi Tim,

Are you running in Gov mode and set RPM??

If you use Set RPM you need to enter gear info, motor KV and pole count and amount of cells... then when you enter your HS rpms it will have a pop up that tells you if the ESC will be "HAPPY" or not...
If you need a walk thru on how to do this set up, and you have a castle link, I can give you my phone number and I could give you a hand to do the set up....

Stan

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

PM  EMAIL  GALLERY  Attn:RR  Quote
02-06-2017 07:22 PM  9 months agoPost 19
ssmith512

rrKey Veteran

Indianapolis, IN USA

My Posts: All  Forum  Topic

Tim,

As a comparison, my Roban 700 Superscale Cobra which has the exact same mechanics as yours, runs on 2ea 6S 6000mAh batteries (12S), 1200rpm headspeed with Castle Talon 120 ESC, I can fly for almost 14 minutes.

Steve

PM  EMAIL  GALLERY  Attn:RR  Quote
02-06-2017 07:29 PM  9 months agoPost 20
doorman

rrProfessor

Sherwood, Arkansas

My Posts: All  Forum  Topic

Too Low

Hi Steve,

What if the set up in your ESC??
Also I think you might be on the lighter side with the Cobra..
At 1330 I am just in the proper range (per the ESC in Set RPM) and at that I am playing with tail blades to keep the tail in line.. Big fin behind my tail rotor and same on the 429 that Tim is running.....
Have you checked for heat?? I do have a "little" practice setting up the CC esc's..

Stan

AMA 2918-Team JR, Spin Blades, East Coast Scale Helicopter,Castle Creations

PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 3783 views
Scorpion Power Scorpion Power
HelicopterScale Model RC Helicopters › Scale head speeds
 Print TOPIC  Make Suggestion 

 9  Topic Subscribe

Saturday, November 18 - 10:26 am - Copyright © 2000-2017 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online