Ultimate Head Speed Calculator

[BruceW]

I'm not ready to announce this application in the main forum section yet but thought I'd share this with everybody in the Mikado section to start with since most of my time is spent here.

This is the ultimate Windows based head speed calculator and has a few features I think are better than the javascript ones being run on other sites. It is even custom branded with a hot link button to launch Helifreak.com. It was written over the weekend so its not completely done and I have more features planned. The idea came about when I was researching motors, desired head speed, pinion choices, cell count, etc. etc.

The application is fairly self explanatory so try it and see if you like it. There is more to come and I'm even thinking of making a Mac version to please the minority but that will be later unless I get a push for it.

Features:
1. Common motor type list (more to come) to auto load KV rating
2. Common gear type list (more to come) to load main gear teeth
3. Pinion and efficiency slider along with manual entry
4. Battery cell selection
5. Battery quality settings (min, normal, max loading voltage levels but its not entirely accurate)
6. Dynamic gear ratio
7. State save between sessions.
8. Head speed reading a different load settings (based on battery quality and type)

Next:
more stuff...:wink:

The main thing I like about this calculator is that you don't need to use two different types of entry fields to find desired head speed or desired pinion size since the slider makes it dynamic and easy to see. Also, the other sites use calculators that use a fixed voltage per cell (3.7V) for calculating head speed and don't take into account load or battery quality.


HSCalc.zip (153KB) - http://brucewsb.s3.amazonaws.com/Files/HSCalc.zip



Enjoy and let me know what you think,
Bruce

[Klinger]

Great calc! Would love to see more motors listed as i know its on your to do list.
Tango's
Actro's
Neu's
would be great
cheers

[BruceW]

Originally Posted by Klinger

Great calc! Would love to see more motors listed as i know its on your to do list.
Tango's
Actro's
Neu's
would be great
cheers

I'm thinking of making an online database where others can help fill in the info and then I just import it as an XML file.

[Mercuriell]

Great work man - good idea about the db too !

[Eyefly]

Great calculator guys! Already on my desk-top.

[AndreasM]

OK, I beg forgivness directly but I'm a programmer by profession and have a habit of testing UI, so don't take this the wrong way... It is a great program! (I just found some inconsistencies :-)
The tab order is weird, is it by design or accident?
If I enter a number for Pinion size, the slider don't update to that value. But I really like the slider idea!
We'll have to help with some ideas for motors, I agree...

[BruceW]

Originally Posted by AndreasM

OK, I beg forgivness directly but I'm a programmer by profession and have a habit of testing UI, so don't take this the wrong way... It is a great program! (I just found some inconsistencies :-)
The tab order is weird, is it by design or accident?
If I enter a number for Pinion size, the slider don't update to that value. But I really like the slider idea!
We'll have to help with some ideas for motors, I agree...

No worries, thats why I asked for feedback...and thanks for finding those. I just fixed the tab order, and the update of the pinion and efficiency slider position. The tab order was wrong because I had moved some controls and forgot to reorder them.

There is a new version up now - 1.0.2 (lets call it beta until it runs perfect:wink.

Bruce

[Foamy Love]

Very Nice!

[JKos]

What are the definitions of the three load levels? Is the efficiency calculated from the motor parameters and operating point or a user defined input? If operating point, which load level?

A very useful addition would be estimated current values for each load level.

Thanks,
John

[BruceW]

Originally Posted by JKos

What are the definitions of the three load levels? Is the efficiency calculated from the motor parameters and operating point or a user defined input? If operating point, which load level?

A very useful addition would be estimated current values for each load level.

Thanks,
John

The idea behind the load levels is that when the helicopter is spun up with no load (i.e. on the ground with 0 pitch), easy flying - medium load, and hard 3D - high load, the voltage per cell will drop to a certain level from the full charged state and that will determine the head speed. Of course, when you ease up on the load the voltage will rise again. The normal head speed calculators usually take 3.7V per cell as a fixed factor in the calculation and this isn't really accurate for determining head speed. A higher C rated batter is going to have less voltage drop than a lower C battery and hence, head speed will be higher.

Efficiency is more of a general fudge factor that takes into account energy loss in the gearing, motor efficiencies, blades, etc. Mostly people plug in around 90% but some motors have a rating of 85%. As an example, the Scorpion HK-2221-8 on my Trex has a higher tached head speed than the calculation stats using 90% so I have to dial up the efficiency rating to 97% to match real world numbers. That's another factor I'd like to acquire from users to plug into the database.

The current (Amps) load is going to be based on the motor type, blades, motor efficiency, cells, helicopter weight, etc. so its hard to guesstimate. But I am planning on loading more motor data to get better stats such as optimal motor speed, watt rating, etc. so stay tuned. To do this, I will probably need to build an online entry form and ask for help from the Freaks to fill in the data.

Bruce

[JKos]

Bruce,
I'm not sure basing load level on cell voltage is all that usefull as it makes some setup assumptions that simply may not be true. It assumes the user is choosing a battery setup which will actually be loaded that heavily.

I guess if your tool is meant for simple, back of the envelope type setup guesstimates, then perhaps it is just fine. I just think you could add a few more things that would take a it up a level or two but stay easy to use. Somewhere between what you have thus far and the famous K.C. spreadsheet would be nice.

> The current (Amps) load is going to be based on the motor type, blades, motor efficiency, cells, helicopter weight, etc.
> so its hard to guesstimate.

So don't guesstimate, calculate it.

Thanks,
John

[Mathias]

Great!

I would like to see Z-Power 1150kv on the calculator.

[jamesotron99]

What did you use to write this? If it's .NET I'll give it a shot under Mono on Mac and Linux.

[BruceW]

Originally Posted by JKos

So don't guesstimate, calculate it.

This is only version 1 (written over the weekend) so there is room to add more calculations and data. I'll look into adding other variables that can be used for more stats.

Originally Posted by jamesotron99

What did you use to write this? If it's .NET I'll give it a shot under Mono on Mac and Linux.

I used MFC (C++) but will probably re-write it in wxWidgets which is portable across multiple platforms.

[th3tick]

One other thing to consider is something like "optimal governor" setting. That is, optimally, I should try to keep my governor at, say, 85%, so what I'm after is what the resulting headspeed would be at 85% of the calculated value.

Functionally, you'd just need another slider with values 1-100%, and a default of 85.

As far as "load" or voltage, on 6S, I see mine do a nice steady decline under load from ~23 to ~21, but it holds across that range well, passing the midpoint almost exactly half-way through the flight. My point being the 3.7V/cell base calculation is a good average to consider anyway, IMHO.

John

[th3tick]

One other thought: while you're storing motors, also include max RPM, and you can back-calculate whether the setup you have will exceed it.

John

[BruceW]

I saw the voltage drop theory based on different loads from MrMel's head speed calculator page and figured that was something others were using but maybe its not. Based on JKos's hint about the KC spreadsheet, I'll look into adding a more advanced info page with more parameters that can be entered to better predict head speed. This will probably require gathering more information about motors, blades, weight, etc.

So, does everybody want me to take out the different voltage loading RPM stats and keep that page simple using 3.7V/cell? The plan is to now add an advanced tab with more tweakable parameters. There will also be a page with just motor stats.

Thanks for the input.

[BruceW]

Originally Posted by th3tick

One other thought: while you're storing motors, also include max RPM, and you can back-calculate whether the setup you have will exceed it.

John

I was planning on adding that also :wink: ... along with motor RPM and percentage of max.

[th3tick]

Originally Posted by BruceW

There will also be a page with just motor stats.

Please be sure to include the pole count. I need that for my brushless headspeed sensor with the E-Logger, and it sure is a pain to find sometimes!

Making a full sheet of motors in and of itself is a worthy reference!

And thank you for taking this (what will turn into) monster on!

Would it be worthwhile for this to be online instead of a downloadable package? That way I could, in theory, run it on my Solaris box too

John

[pcliftonjr]

That's good stuff man! Thanks,

Paul