Head Speed/Battery Calculator for Windows

[HELINHAWAII]

Bruce,

Simply awesome man! Any chance you could get that over to MAC?

[BruceW]

Been too busy with work and vacations lately to put the necessary time into the calculator but a Mac version is something I would like to do. Keep meaning to get back to it and hopefully time will be found this summer.

[Wyldman]

Awesome job, Bruce! This is making my life much easier.

One suggestion: how about adding an optimum target headspeed for each class of bird. Doesn't have to be exact, but a good rule of thumb to shoot for for each size bird that can then be tweaked to the user's needs/wishes.

Thanks again, man!

[BruceW]

Originally Posted by Wyldman

Awesome job, Bruce! This is making my life much easier.

One suggestion: how about adding an optimum target headspeed for each class of bird. Doesn't have to be exact, but a good rule of thumb to shoot for for each size bird that can then be tweaked to the user's needs/wishes.

Thanks again, man!

Thanks Wyldman,

A target head speed for different helicopters would be a great thing to add and hopefully I'll do it some day. For now I just have minor fixes but its on the list now.


For now, here is the latest:

Uploaded version 1.0.9 tonight with new motors added and several bug fixes along with some little features promised a while back. The original link to the file has been updated but from now on I plan on making changes on my personal blog site http://www.brucerc.com or more specifically there is a page dedicated to the head speed calculator at http://www.brucerc.com/software/hscalc/. Of course I'll report back here when there are changes so subscribers can get notified.

You might also notice that I'm looking at creating an easier to use airplane prop calculator. Since I've been flying planes lately I figure that would be the next step. Of course more fixes to the helicopter calculator will come first though.

Thanks for the feedback. An XML import/export/merge feature would make this really nice so all of you could add data and then send it back to put it in a master db. This is a big dream and since it has taken me this long to get back to the tool I'll need to change my productivity rate to make that happen.

[Ecklund1]

Nice utility Bruce! Thanks for the time & work!

Jeff

[akaduck]

Any chance of seeing the source code?

[BruceW]

How much? The calculation part or the whole thing?

[BruceW]

Added version 1.0.10 of the calculator tonight.

Modifications are:
1. Added motor and gearing for the Trex 250
2. Added gearing for the Mikado Logo 600 mod 1.0 (106T)
3. Corrected the MSH Protos gearing (now 93T)

Can be downloaded here:
http://www.brucerc.com/downloads/HSCalc.zip

with a description of the changes here:
http://www.brucerc.com/software/hscalc/version/

[NitroAl]

Bump!

[Gerald71]

What cell voltage I have to use to calculate correct head speed?
My 3s 2.200mAh is at 4.20V after charging and about 3.70V after flying and using about 1.700mAh. So my battery is at nominal voltage at the end of the flight?
The head speed shown is at 100% throttle?

I measured my head speed with a very cheap tool which I'm not sure its working correct. It showed me a head speed of 2.900rpm at 0° with my 3550KV motor 11t pinion at 60% throttle. Comparing to the head speed calculator this is way too high, which shows 2.456rpm at 3.70V with 150t main gear.

My setup: CopterX 450AE V2
Motor: CopterX (CX450-10-06) 430XL Brushless Motor 3550KV & 50A Brushless ESC
Pinion: 11t, 150t main gear
Throttle curve: 0, 25, 42, 51, 60, 65, 70, 75, 80 (reduces many times already)

[BruceW]

If you have the 430XL, the rated KV is 3700 not 3550. Plugging that in to the calculator gives about 2800 using 94% efficiency (I've found the efficiency factor is usually a little higher than the standard 90). Are you the ESC in governor mode?

[Gerald71]

The CopterX 430XL should be 3550KV (search the internet). But I'm not sure if this is correct.
I'm not using governor mode (not sure if the ESC has one).

I tested my tachometer be measuring flourescent lights. It shows 3.000rpm (50Hz here in Austria). I suppose it should be 1.500rpm because of 2 blades setting? Changed setting to 1 blade and I read 6.000rpm. Maybe my tool is defect?

[BruceW]

Opps, my bad, I thought it was an Align 430XL.

[jcinauz]

You can do IT! I know you can

[rcjames]

Originally Posted by BruceW

Opps, my bad, I thought it was an Align 430XL.

Hey bruce thanks for creating head speed Calculator. I'm using this in Linux. To run it
I used wine. Seem to be working well. Here a picture of proof for those people that are
interested to know if it work in Linux. Yes I'm a big fan of Android os too.

[Digger1973]

I just found this thread doing a google search. Nice little program. It deserves a bump. Ever plan on making it an android app?

[Windmanquebec]

I'm replacing my 420 motor(3800 kva) on my blade 450 with a scorpion 2221-8 (3595 kva).
Main gear 140
pinion 10

When I enter those value for the 420 motor I get 2712 rpm at 3.7 volts. Is that assuming I run at 100% throttle?

If I run at 72% throttle curve will the resulting rpm be (2712 X 72%) 1952?

What about voltage. 2712 is at 3.7v, so is it that when my battery is fully charge at 4.2V I'll get 3078 rpm as per the calculator with 100% throttle again.

Assuming What I just write is good :

If I want to acheive 1952 rpm as I had originaly (2712 X 72%) and I have a 12 pinion with my scorpion motor, if I set my throttle curve at 63% I should get the same result?

Scorpion 12 pinion at 3.7v = 3078

1952 rpm = % * 3078rpm
% = 1952 / 3078= 63%

[Windmanquebec]

Anyone?

[Highspeed1964]

I believe you are correct. Just to clarify, 3.7v is per cell as I'm sure you are aware. The simple math is that you multiply the total voltage times the kV rating of the motor and divide by the gear ratio and then multiply by the efficiency to get your head speed.

So with your original motor/gear combo:

11.1v * 3800kV / (140 / 10) * efficiency = 42180 / 14 * .9 = 2712

This is at the nominal voltage. However, initially a 3S battery will produce 12.6v so the head speed would be higher (3078rpm) as you have seen (I assume) in the "Variable Load" section with the "Cell Voltage" slider all the way up. The point is that at the highest voltage produced (full throttle) you would get the speed indicated.

You can take it from there that the figures this calculator provide are for full throttle and so the calculated speed for the other motor/gear combo correlate accordingly. Then the speed (without governor of course) at a given throttle setting would follow your understanding.

This also assumes that both motors produce an efficiency of 90% and this is no load conditions. My experience has shown that with blades on at zero degrees pitch I am getting closer to an 85% efficiency but that could be due to the ESC being underpowered for the motor I am running or other external influences as well.

Hope that answers your question.

Highspeed