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HomeAircraftHelicopterMain Discussion › Trex 600ESP Low headspeed/ Max Endurance Project Trex 500 Scorpion Motor NOW A 700ESP SOON TREX 800
08-14-2010 12:41 AM  8 years agoPost 41
rjhpilot91

rrApprentice

somers point, nj

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Sidney,

Headspeed is the biggest consumer of power. Weight only matters if you keep the same headspeed. I ran the stock 600 power system at one headpspeed and then ran it with 700 blades and it was running very hot and using lots of amps. When I dropped the headspeed by 60% my amp draw became half of what it was with a 600.
My 700 setup uses a TREX 500 motor and esc and uses less amps than my trex 500 did, due to the lower headspeed.

However if you spool the heli up too fast with those huge blades you will suck up a lot of amps until you get the RPM up. What I do is use all 3 flight modes for spool up. I start in idle 2 with a max esc setting of 20%. Then I go to idle 1 and bring the RPM to 40%. Then I switch into normal mode to fly around. This produces a very slow controlled startup which I use every time so I dont over amp the motor or strip main gears.

As far as tail authority with the 550 RPM, I think its doable with the rotortech 120mm blades. They seem very efficient and even at 600 RPM on the 3s battery the tail had plenty of authority in both directions, so I'm confident that it will remain effective down to 500RPM!

Helicopters don't fly, they beat the air into submission!

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08-14-2010 03:53 AM  8 years agoPost 42
Sidneyw

rrApprentice

Huntersville, NC

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Weight only matters if you keep the same headspeed.
rjhpilot, thanks for the reply. That's exactly I was looking for.

When I was toying with multi-blades the weight of the blades matters at the same HS comparing to lighter blades. Of course, tons of expert disagree.

I just got the same motor and will do some test/experiment on Swift 16 using 600mm blades. Thanks to your thread here.

I do know heavier blades will take longer to slow down from energy stored. However, maintain the RPM + during increase drag from collective change will require more energy. Thus, heavy rotor mass and or increase AUW will require heavier load for tail rotor.

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08-23-2010 06:13 PM  7 years agoPost 43
rjhpilot91

rrApprentice

somers point, nj

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Hit 599 RPM!
After increasing the pitch of the main rotor blades it slowed the rotor speed down to about 650 in a hover using approx 15 amps. Heres the graph from eagletree to prove it. It even hit 599 RPM in a descent!

Helicopters don't fly, they beat the air into submission!

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10-26-2010 08:41 AM  7 years agoPost 44
heli_headcase

rrKey Veteran

Hovering around Atlanta

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Finally! Edited and posted video of my low-speed heli!!!
http://www.youtube.com/watch?v=5G1vdSbU_tM

Watch at YouTube

Some details of the project are available on the video clip's description page and also at the link to my thread posted earlier.

It's available in 720P HD for those that like details. The morning clouds look really cool

Enjoy!


HHC

So many heli's - too little time...

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10-26-2010 10:33 AM  7 years agoPost 45
Richardmid1

rrProfessor

Leeds, England

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Assuming you have 8000mah to use if your averaging 15 amps you should be good for 32 mins shouldn't you?

Im guessing you've tried lower gearing with increased throttle settings?

25 mins just doesn't seem very long for such a project thats all.

60% of the time, it works every time!

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10-26-2010 02:45 PM  7 years agoPost 46
heli_headcase

rrKey Veteran

Hovering around Atlanta

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I wasn't trying for duration as my goal was only to fly with a slow and realistic head speed.

I don't know where you came up with 8AH (8000mah). My packs are old TanicPacks 12C 4960mah 12S (2X 6S). It's been a while since I did any data logging but as I recall my average watts was about 550 at around 12A, or 41W/lb. Gearing has always been to get 600rpm on 12S with some headroom for the ESC's governor.

Thanks.


HHC

So many heli's - too little time...

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10-26-2010 02:59 PM  7 years agoPost 47
Richardmid1

rrProfessor

Leeds, England

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Sorry I assumed you were running the 2 packs in parallel (around 10,000mah 6s) 80% = 8000mah.

60% of the time, it works every time!

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10-28-2010 06:27 PM  7 years agoPost 48
heli_headcase

rrKey Veteran

Hovering around Atlanta

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12S1P vs 6S2P...
I could have configured the heli that way and gearing options are virtually unlimited but, my mindset is toward higher voltage, lower current which explains the 12S vs 6S pack configuration.

Also, I was trying to take advantage of swapping out some huge 5S packs (10S3P total) with the 12S setup on the same gearing/motor configuration and that was a 10% voltage change vs 20% change if I had tried to fly 6S (total cells) and then plugged in 5S using the same gearing/motor. The 10% drop in voltage was enough trouble (the ESC governor lost all its reserve) so clearly a 20% drop in voltage would "never fly", so-to-speak.

Thanks


HHC

So many heli's - too little time...

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10-28-2010 08:16 PM  7 years agoPost 49
Richardmid1

rrProfessor

Leeds, England

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6s 10,000mah vs. 12s 5000mah would give roughly the same flight time anyway assuming they are producing the same watts. However in my experience you are limited to certain Kv 12s motors, using a lower kv, more efficient motor on 6s would give you longer flight times than running a 12s setup with half the mah's.

Lets say you are pulling 15 amps on 12s and 30 amps on 6s, you could switch to a lower kv motor on 6s and be pulling 25 amps which would then give you longer flights than the 12s setup.

60% of the time, it works every time!

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10-28-2010 08:32 PM  7 years agoPost 50
heli_headcase

rrKey Veteran

Hovering around Atlanta

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I'll have to think over what you just posted, thanks, but my goal wasn't flight time, it was purely the low rotor speed and what it could or could not do. The idea was to get a more scale-like, realistic rotor appearance and sound and then what control difficulties what I see.

I didn't have a selection of big motors when I started this project but did have lots of gears

Shouldn't you start doing more hover practice?


HHC

So many heli's - too little time...

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10-29-2010 10:47 AM  7 years agoPost 51
Richardmid1

rrProfessor

Leeds, England

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I should but I get bored after a couple of minutes! lol.

A lower kv motor on 6s would also give you a quieter less screamy motor noise and also due to the larger pinion a quieter gear noise.

60% of the time, it works every time!

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11-06-2010 06:52 PM  7 years agoPost 52
wakanars

rrNovice

Palm Beach Gardens, FL

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hello guys
what rpm can i use with my mini titan to increase my flight time
i am using 6s 1350mah lipo with 1630kv motor
tks
-roger

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11-06-2010 07:25 PM  7 years agoPost 53
AirWolfRC

rrProfessor

42½ N, 83½ W

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To make the efficiency even greater, find some asymetric blades.

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11-08-2010 10:18 AM  7 years agoPost 54
Richardmid1

rrProfessor

Leeds, England

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hello guys
what rpm can i use with my mini titan to increase my flight time
i am using 6s 1350mah lipo with 1630kv motor
tks
-roger
Depends what style of flying your doing but if you use an 11T pinion you would be getting around 2600rpm which is enough for sport flying, for 3D use a 12T pinion (2850rpm), both at 100% in idle up.

With the 11T you should get about 7 mins minimum and about 6 mins minimum with the 12T. (flown more gently you could add a couple more mins to these flight times.)

60% of the time, it works every time!

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02-03-2012 03:54 AM  6 years agoPost 55
digikas

rrVeteran

London, Ontario, Canada

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Thank you guys for the great post , so How could I extend my flight time for the trex 500 ?, any suggestions ?, I am looking at 15 minutes flight time ?

Scale life or no life !

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