RunRyder RC
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 1542 views POST REPLY
HomeAircraftHelicopter
e-
Electric Conversions
› Correct me if i`m wrong on figuring headspeed
04-08-2010 06:34 PM  8 years agoPost 1
scott s.

rrElite Veteran

Orange, Ca.

My Posts: All  Forum  Topic

motor kv X voltage = rpm`s divided gear ratio equals headspeed using 100% in throttle curve right?

(example) 684 kv X 42 volts = 28772 rpm`s divided 9.5 = 3028 headspeed

+ or - type of blades and all the other stuff. Am i right ?

PM  EMAIL  Attn:RR  Quote
04-08-2010 06:37 PM  8 years agoPost 2
Wingman77

rrProfessor

Pulaski Tennessee

My Posts: All  Forum  Topic

yes that is correct if you are running 100% throttle. the only variation of that is the voltage of the battery under load. if you are flying a 3s pack(25c) and normaly get about a 4 min flight you would figure on the battery voltage being around 11v

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
04-08-2010 06:40 PM  8 years agoPost 3
nivlek

rrProfessor

Norfolk England

My Posts: All  Forum  Topic

The motors Kv is usually the off-load rpm per volt , if you multiply your calculated rpm by 0.85 you will be a lot closer to the loaded rpm .

At the end of the day , it gets dark .

PM  EMAIL  Attn:RR  Quote
04-08-2010 07:30 PM  8 years agoPost 4
scott s.

rrElite Veteran

Orange, Ca.

My Posts: All  Forum  Topic

Setup on 700 conversion
Well i have the setup in my example, a 10S setup

and after 1 good flight on the second flight it exploded in mid-air

my guess is it poped the short link and boom struck

Do you think too much headspeed the cause ?

BTW, i though the kv was less or i would have geared it different.

PM  EMAIL  Attn:RR  Quote
04-08-2010 07:47 PM  8 years agoPost 5
Wingman77

rrProfessor

Pulaski Tennessee

My Posts: All  Forum  Topic

so you have a 684kv motor on 10s in your 700 with a 9.5 ratio?

first off I would figure your voltage in flight to be around 37v, it could be a bit less I don't know what batteries you are using. but that would put you around 2600 on the head which is WAY too fast.

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
04-08-2010 08:16 PM  8 years agoPost 6
scott s.

rrElite Veteran

Orange, Ca.

My Posts: All  Forum  Topic

Well
It`s been an expensive lession to be sure.

PM  EMAIL  Attn:RR  Quote
04-08-2010 09:13 PM  8 years agoPost 7
Wingman77

rrProfessor

Pulaski Tennessee

My Posts: All  Forum  Topic

there are so many expensive lessons in this hobby....

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
04-08-2010 10:02 PM  8 years agoPost 8
scott s.

rrElite Veteran

Orange, Ca.

My Posts: All  Forum  Topic

Nivlek
so using what i gave here my headspeed should be what?

PM  EMAIL  Attn:RR  Quote
04-08-2010 10:17 PM  8 years agoPost 9
nivlek

rrProfessor

Norfolk England

My Posts: All  Forum  Topic

684 x 37v (nominal voltage) / 9.5 x 0.85 = 2264 rpm . Depending on how efficient your set up is and how well your batteries hold their voltage under load , you could be 100 rpm out either way .

At the end of the day , it gets dark .

PM  EMAIL  Attn:RR  Quote
04-09-2010 05:21 AM  8 years agoPost 10
Stolla

rrKey Veteran

Port elizabeth South Africa

My Posts: All  Forum  Topic

Use mr mels headspeed calc (ready-heli site or his) it's very close to real life performance and convenient, also very helpful to see how different setups perform.

Common sense may not be common after all

PM  EMAIL  GALLERY  Attn:RR  Quote
04-11-2010 07:54 AM  8 years agoPost 11
scott s.

rrElite Veteran

Orange, Ca.

My Posts: All  Forum  Topic

110HV Castle
Is what i`m using on this . Not using Gov. mode.

I was running 100 95 100 throttle curve.

If i use like a 70 straight line throttle curve i`m not being efficent wih the motor am i?

Does`t that heat up the ESC too?

PM  EMAIL  Attn:RR  Quote
04-11-2010 08:02 AM  8 years agoPost 12
nivlek

rrProfessor

Norfolk England

My Posts: All  Forum  Topic

Your esc will definately run hotter at 70% .

At the end of the day , it gets dark .

PM  EMAIL  Attn:RR  Quote
04-11-2010 08:52 AM  8 years agoPost 13
PJRono

rrKey Veteran

Minnesota, Ya!

My Posts: All  Forum  Topic

Mr Mel likes to run alot of headroom in the ESC which is not a bad thing. Yes, it can create heat in the ESC, but it can also create alot of power at the head. It all depends on the motor and gearing you use, and how you want to fly the heli.

If you skip me I can't play!

PM  EMAIL  GALLERY  Attn:RR  Quote
04-12-2010 05:01 AM  8 years agoPost 14
scott s.

rrElite Veteran

Orange, Ca.

My Posts: All  Forum  Topic

Here`s my problem
I`m using(correction,trying to use) a trex 700 coversion kit that claims you can use the stock gearing.

Well, using this setup
684 kv X 42 volts = 28772 rpm`s divided 9.5 = 3028 headspeed

I stripped 3 stock main gears, ruined a 35 dollar kde main gear when it exploded in midair.

Very unhappy at this point, many others around me flying their e700 but i am having the worst luck.

I`m not a novice at helis, been in it 16 years but this electric is kicking my butt.

PM  EMAIL  Attn:RR  Quote
04-12-2010 05:02 AM  8 years agoPost 15
scott s.

rrElite Veteran

Orange, Ca.

My Posts: All  Forum  Topic

Mr Mel likes to run alot of headroom in the ESC
what does this mean?

PM  EMAIL  Attn:RR  Quote
04-12-2010 07:06 AM  8 years agoPost 16
misskimo

rrElite Veteran

Alaska 17 years, before mississippi for 31y

My Posts: All  Forum  Topic

hey, good rule of thumb for setups for me was. 20C batteries, use 3.8 volts, 45C batteries I use 4 volts ,
your setup is high. to high, that will cause alot of unwanted torque for the drive train. Gear stripping when you bump the HS lower. its better to use a 450 to a 550 KV . figure out you gear train with the 10S batteries and for 3D , gear it for a max HS of 2400 and bump down to 2000 to 2100 .

T

PM  EMAIL  GALLERY  Attn:RR  Quote
04-12-2010 03:42 PM  8 years agoPost 17
scott s.

rrElite Veteran

Orange, Ca.

My Posts: All  Forum  Topic

Gearing
I don`t think there`s gearing out there to get down to 2100 using this motor unless i go down on cell count right?

Seems all the new electrics are using 115 tooth mius curtis` rave 90

and i can`t find a smaller pinion for a 5mm shaft.

PM  EMAIL  Attn:RR  Quote
04-12-2010 03:45 PM  8 years agoPost 18
Wingman77

rrProfessor

Pulaski Tennessee

My Posts: All  Forum  Topic

or go down on motor KV.

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
04-12-2010 03:54 PM  8 years agoPost 19
scott s.

rrElite Veteran

Orange, Ca.

My Posts: All  Forum  Topic

go down on motor KV.
i`m trying to make this work, i`m already into it over $500.00 with cost of motor and all the trouble.

Problem is ya i could start all over but than what am i going to do with this motor?

Ya , i guess i can sent it back to upgrade 4 half the cost.

Sucks.

PM  EMAIL  Attn:RR  Quote
04-12-2010 03:57 PM  8 years agoPost 20
Wingman77

rrProfessor

Pulaski Tennessee

My Posts: All  Forum  Topic

I see the ratio is 9.5 but what is your pinion and main gear tooth count?

PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR  Quote
WATCH
 2 pages [ <<    <    ( 1 )     2     NEXT    >> ] 1542 views POST REPLY
HomeAircraftHelicopter
e-
Electric Conversions
› Correct me if i`m wrong on figuring headspeed
 Print TOPIC  Make Suggestion 

 5  Topic Subscribe

Saturday, August 18 - 6:58 pm - Copyright © 2000-2018 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online