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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › Low Headspeed project-----19 minute flights!
06-21-2009 08:18 PM  11 years ago
ΦZapper

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It's HOT here!

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amazing flight times!
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06-21-2009 09:25 PM  11 years ago
what_the_helli

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cookeville, tn USA

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yes, yes, we all know about this stuff

I put the fun in dysFUNctional :)
Team KBDD & Funding by TnPrintMasters.com
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06-21-2009 10:08 PM  11 years ago
billiano

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Greece ,Patras

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Nice stuff give me a gallon.
P.S:Can I use it also on my mother's in law wheelchair wheels?
Esprit Model Flight Team
Kasama Srimok 90N FBL
TDR Rigid 90
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06-22-2009 02:41 AM  11 years ago
Carey

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Allentown USA

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This thing going in the derby or what?
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06-22-2009 07:37 AM  11 years ago
Lota Fun R

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Acton, CA (So. Cal.)

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Hover for 19 minutes? :headscratch: Ok......

I wonder how long a nitro 600 would hover on it's lowest setting?

Probably so long it would seem like you were fishing.
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06-22-2009 07:42 AM  11 years ago
Lota Fun R

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Acton, CA (So. Cal.)

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I've been using Honda polish on my heli for a while now, only because it works great. How slick it makes the blades I don't know, that's not why I use it but if might be just the ticket..?
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06-22-2009 08:16 AM  11 years ago
blbills

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Provo, UT

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I know that gearing down has been beaten to death but you mentioned that you were going to get a 12s motor for your scale project and you may want to consider KV. I'm probably preaching to the choir but you can effectively "gear" the heli down by getting a lower KV motor.

Just something else to consider.
Brian
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06-22-2009 03:03 PM  11 years ago
ChristianM

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Oslo, Norway

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The point is to get as long a flight time as possible and running 100% percent no matter what the motor or gearing is going to use more battery power.
This is not correct. When you are reducing the percentage then the ESC is reducing the voltage that the motor "sees" which lowers the RPM. The load from the head determines the current the motor draws, not the ESC. So for a given power output the motor and consequently the ESC will draw more current at a lower percentage (i.e. lower voltage) than at 100% and thus the internal resistance will be higher which will result in more heat and reduced flight timer. So for max flight time then your best option is to select a motor with lower Kv value and an appropriate pinion to get the desired head speed at 100% throttle.

Christian
Burn fuel, be happy
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06-22-2009 03:41 PM  11 years ago
LonR

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Macomb,Mi

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The lower head speed the more chance of a tail blow out right?600LE,OS55,OS PowerBoost pipe,Align 610's,Spartan
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06-22-2009 04:42 PM  11 years ago
Flying Tivo

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Monterrey,NL,Mexico

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Speed up gear
He can use a speed up gear for the tail, and he would not have any problems with blowouts.

Felipe
If life throws at you lemons......Squirt some lemon juice in the eye of your enemy!!!!
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06-22-2009 05:00 PM  11 years ago
AirWolfRC

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42½ N, 83½ W

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A "tail blow out" is the result of all of a sudden too much collective as in some acrobatic maneuver. If you're trying "scale" flying, it's not a problem.
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06-22-2009 05:16 PM  11 years ago
GyroFreak

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Orlando Florida ...28N 81W

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tried the windex trick on the blades shown here to get an extra two minutes flight time?
I polish my blades with propwash.
I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?
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06-22-2009 09:28 PM  11 years ago
LonR

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Macomb,Mi

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Thanks for letting me know guys .I allways thought it was low headspeed,I learn somthing new everyday haha.600LE,OS55,OS PowerBoost pipe,Align 610's,Spartan
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06-24-2009 02:01 AM  11 years ago
rjhpilot91

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somers point, nj

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The project is still going well. Got a lot more flights logged and am averaging 15-16 minutes per flight. Temperatures are manageable on the ESC and batts are very cool.

The sound it makes is awesome. Still plenty responsive for scale flying!
Helicopters don't fly, they beat the air into submission!
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06-24-2009 04:08 AM  11 years ago
GyroFreak

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Orlando Florida ...28N 81W

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Here is my thread, similar to yours on my streched Razor 600E swinging 720 mm blades at 1450 HS rpm. Next I will start lowering HS to see how the current and stability works out using Eagle tree data logger.
.
http://runryder.com/t504071p1/
I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?
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06-24-2009 04:40 AM  11 years ago
LoveMyTrex

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Hamilton,VA

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running at 50% throttle on the ESC is very inefficient. also the throttle % does not have anything to do with current draw other than the lower throttle % the more energy is wasted as heat.

link here : http://allthingsthatfly.com/Archive...=2008&month=Sep

please listen to ATTF #92 PSC roundup. this is a segment with lucien miller from inov8tive designs, distributors of the scorpion motors. he explains why it is definitely more efficient to run at 100% throttle.

you have to think with electric the motor only pulls as much current as it needs to spin the RPM you tell it to. the motor will never draw more current than it needs. if you need proof of this simply take the motor out of the heli and run it up to 100 % throttle with nothing attached with a watt meter on it. I am sure it will not be drawing 40 amps like you say it will.
600N 55HZ/SAB-55 600V's
700N 91HZ/SB-20 690V2 V's
90SG 91HZ/SB-20 710V2 V's
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06-26-2009 06:55 PM  11 years ago
rjhpilot91

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somers point, nj

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Stretch to 90 size on only 6 cells 850 RPM! 710 main blades 105mm tail
I understand the theory behind brushless motors spinning at 100 percent for max efficiency but numbers from a data logger don't lie.

To test this theory I put my old sport throttle curve 0-40-65-83-100 into the radio and flew it in a hover as well as slow forward flight. Heres the numbers:

Main RPM Hover 1350 MAX 1497 MIN 1300
Hover AMPS 20-22

3 minute flight 1005 mah used
Battery temp 88' ESC temp 160'

Thats 335mah used per minute compared to 197 on one of my tests. Yes the ESC does run hotter due to the inefficiency of these low curves but I have remedied the ESC temperature issue now.
Helicopters don't fly, they beat the air into submission!
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06-26-2009 07:08 PM  11 years ago
rjhpilot91

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somers point, nj

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Heres the results after completing the trex 700 stretch with Radix 710 mains and 105 mm tail blades.

I also added 2 5V PC cooling fans under the Trex bottom frame up front where I mount my ESC and wired those to run off of a Zippy 2s 1800 mah pack. These fans produce a decent amount of air and use only 88mah per 10 minutes for both fans! This should give me at least 10 flights before I have to charge the fan pack. I also removed the plastic covering from the ESC so that it cools a little better.

My first flight with the 710's I was able to lift off with only 850 RPM on the head. It vibed a bit but was definitely flyable and controllable. In a descent the headspeed even dropped to about 780!

Heres the specs from my last flight this morning in the final configuration:

4 minute flight; no cooling fans on
RPM 1050
AMPS 14-16
870mah used (221 mah minute)
Battery temp 92'
ESC temp 136'

After a 1 minute shutdown to check for temps I did the second flight

4 minute flight with cooling fans on
RPM 1050
AMPS 14-16
840 mah used (215 mah minute)
Battery temp 96'
ESC temp 109'

Thats a 27' degree temperature drop after already being at 136' from the previous flight. The motor was at 137' and everything else was very cool. This stretch project is more efficient and runs cooler now than my stock Trex 600 ever flew.

This project has been very fun and this configuration will stay like this until it needs to be tweaked for the scale fuselage.
Helicopters don't fly, they beat the air into submission!
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06-27-2009 03:26 AM  11 years ago
LoveMyTrex

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Hamilton,VA

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I understand the theory behind brushless motors spinning at 100 percent for max efficiency but numbers from a data logger don't lie.

To test this theory I put my old sport throttle curve 0-40-65-83-100 into the radio and flew it in a hover as well as slow forward flight. Heres the numbers:

Main RPM Hover 1350 MAX 1497 MIN 1300
Hover AMPS 20-22

3 minute flight 1005 mah used
Battery temp 88' ESC temp 160'

Thats 335mah used per minute compared to 197 on one of my tests. Yes the ESC does run hotter due to the inefficiency of these low curves but I have remedied the ESC temperature issue now.
yes, but did you change the pinion? if the answer is no all you did was prove that if the headspeed is higher it draws more amps.
600N 55HZ/SAB-55 600V's
700N 91HZ/SB-20 690V2 V's
90SG 91HZ/SB-20 710V2 V's
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06-27-2009 03:34 PM  11 years ago
Big Fil

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Santa Rosa, CA

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Ah ze magic rotorblatten spray

http://www.youtube.com/watch?v=XCRdo_OElhs
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Home✈️Aircraft🚁HelicopterHelicopter Main Discussion › Low Headspeed project-----19 minute flights!
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