Equipment for indoor electric scale models

[gravitywell]

Be sure to detail your electric gear.  I have wanted to try electric free flight for years but just don't have the knowledge.

[SvenH.]

Well you know, there's not a  real lot to know, you need a motor -most probably a geared one- fitting for the prop diameter and , a controller pcb, and a battery (most likely LiPo 1s)... 
Of course you can make a whole science topic about it, but from my experience best is to just start.

[SvenH.]

Some thoughts and experiences on these components:
- Motor: there are tons of different motors, gears, props out there, but most likely I would suggest to buy a set, motor + gear + prop to start with. Just to be exact, in general we use brushed motors as those are easier to control (electronically). For example I use a ø8,5mm x 20mm motor with a 52x10 gear and a 6 x 3 prop on a 600mm wingspan Cessna with a total weight of app. 55g.
- Controler (Electronics): also on this, a huge varitety of possibilities available, but also some specifically designed for Free Flight, e.g. the Zombie Controler (Atomic Workshop), which I can only recommend due to its low weight and simplicity. It's widely used in electric FF so far I know.

[SvenH.]

- Batteries: as usually weight is the most demanding factor on planes, it's always been a challenge to decide on the amount of "fuel" to be carried, especially on electric FF. Today, we have thankfully a big variety of LiPo-Batteries at hand, which in it's nature are the lightest possible electric power sources available today, and thankfully also in very small sizes. With a proximate flight time of just a couple seconds to a few minutes, I for example decided on using a 150 mAh battery on the set-up mentioned above, and still think about reducing it to 75-100 mAh. So, here as well, my suggestion to buy a decent sized one and see how it goes, reduction should still be possible.

[g_kandylakis]

I have split the last messages from the original Piper Tri-Pacer build thread, as the subject is more universal and useful as a stand-alone topic for others too.

To begin with, we are talking mainly about indoor electric scale models as they are being flown under the FAI F4E provisional class rules, mostly flown in Europe. I have no experience about what is done/flown in the US or other countries, so any input on that is most welcome.

In F4E, the models are judged on flight realism, as long as the flight duration is over 15 seconds in order to be considered as a qualifying flight.

In order to achieve that, the most important piece of equipment is the motor "timer", or "profiler", which allows some pre-programming of the motor's RPM and run duration.

The first and most successful profiler so far, as correclty mentioned by Sven, is the Atomic Workshop Zombie timer, which revolutionised the CO2/electric class after its appearance. Until then it was a class dominated mostly by CO2 models, with very rare appearances by electric models. Now, over 20 years later, it is the other way around, with CO2 models virtually non existent in events like the BMFA Indoor Nationals.
https://atomicworkshop.co.uk/product-category/flight-profilers/

Another option that was (is?) available was the K+P timer.
http://kpaero.com/ProductReport.aspx?Category1=electric


More recent addition to the choices is the "Chronos" timer by Jiri Dolezel (excellent choice of a greek word  , meaning "time"). (Sorry, no known link, unless Jiri can provide some more info).

All three definetely operate on 1S batteries, if I am not mistaken. I do know that the Zombie can run on higher voltage, I imagine the others too, with some circuitry. More specialised input welcome.

There is also the timer made by Tonda Alfery's son, which is sadly not commerically available.

Last, there are some attempts in progress, to program the motor run via specific RC systems or even a mobile phone up, as was demonstrated at the last IIFI. Nothing specific yet, although Erik Crins should be posting something relevant soon, I hope.

[g_kandylakis]

Some major characteristics of each of the available options (if there are others out there that I did not mention, by all means add them to the discussion...)

Zombie Profiler

• very light at 1,25 gr.
• brushed motor operation only
• two separate power phases, time and RPM setting for each phase via onboard potentiometers
• ramp option to run power down
• no separate servo operation
• start button to start operation

K+P timer

• slightly heavier than the Zombie
• brushed and brushless operation, via external ESC
• 3 potentiometers for power, duration and decay, requiring a combination of all 3 to arrive at a required flight profile
• no separate servo operation
• operation start immediately upon connecting the battery

Chronos timer

• slightly heavier than the Zombie and the K+P
• brushed and brushless operation, via external ESC
• 3 potentiometers for power, duration and decay, requiring a combination of all 3 to arrive at a required flight profile
• additional servo operation possible, for landing gear operation for examble, two extra potentiometers
• operation start immediately upon connecting the battery

The immediate operation start of the last two is a problem that can be easily overcome through an additional switch, giving enough time to place the model for take-off.

[g_kandylakis]

There is also another profiler I failed to mention, mainly because I have never seen it in action or owned one.

It is the one marketed by SAMS, now available from the Vintage Model Company.
https://www.vintagemodelcompany.com/dual-function-profiler-bomb-drop-version

It is not clear if it drives a brushed motor without the use of an external ESC. It seems to drive a brushless motor with an external ESC.

It also has a servo operation for a "bomb drop", meaning probably a one-way servo actuation.

not much more can be gleaned from the website of VMC, I am afraid.

[dputt7]

   Great survey George, you must spend so much time reading and adding content, it is much appreciated.
Just a slight correction, the K&P Timer comes programmed with a 10 second delayed start after it is switched on. Also there are separate K&P timers for brushed and brushless motors.

[g_kandylakis]

Thanks Dave,

yes, it is a bit time consuming at the moment but I think it is worth it.

Regarding the timers, you are correct, or, I was not clear.

All have a 10 second delay, more or less. It is just that the activation is different. The Zombie does not start upon battery connection, it needs a specific action for the clock to start running while the others start upon battery connection.

As for the K&P, the one I had was for brushed and brushless. And that is what I see on the website too.

[dputt7]

  Well there you go, I thought that while they sold a Brushed Timer the others were only Brushless. I also have a fellow flyer that has just bought a brushed timer for his twin KPO2 powered B25.

[Nigel_M]

There is also another profiler I failed to mention, mainly because I have never seen it in action or owned one.

It is the one marketed by SAMS, now available from the Vintage Model Company.
https://www.vintagemodelcompany.com/dual-function-profiler-bomb-drop-version
not much more can be gleaned from the website of VMC, I am afraid.

It and a range of controllers for similar purposes is made by Forge Electronics https://www.forge-electronics.co.uk/index.php/aircraft.html 

It is also available from Den's Model Supplies for the UK https://www.densmodelsupplies.co.uk/index.php?c=e-zee_timers who sell ten variations(!)

And a couple of the versions from Steven's Aero for the USA https://www.stevensaero.com/product-category/model-airplane-supplies/model-airplane-receivers-servos/ez-timers-control-line-freeflight/

Enjoy browsing!
Nigel

[Nigel_M]

This is part of a longer( ) reply I wrote about K&P timers on HPA2.0. The situation is fairly confusing:

KP sell two timer/controller types which are connected quite differently. One type is used directly between the battery and motor in the same way as Atomic Workshop Zombie flight profilers are used. This type effectively incorporates an ESC.  I've attached scans of diagrams from their instruction below but one is illegible so I may have copied that from a screen image.

The other type is used in conjunction with an ESC and effectively replaces a radio control receiver signal to control the ESC. The schematic that can be downloaded from the KP product list 'Time and Speed Controller' hyperlink refers to this latter type kpaero.com/Documents/KP%20freeflight%20TIMER.doc.

Unfortunately, the instructions that are supplied with KP timer/controllers appear to refer equally to either type as 'KP Aero Timer'. I have a 35 sec timer (item #112 on their product price list) recently bought wherein the instructions show a wiring schematic for a brushless motor which does not/cannot relate to the controller in the box, so I haven't scanned those instructions. The controller unit supplied has two three-pin 'Futaba' connectors with markings for Aux and Motor, no battery connectors, +5V S1, Signal S2 and S3 solder pads, so I haven't a clue how to use that one properly, although I suspect one simply connects the ESC to the Motor connector. I will ask when I come to use it. That's an aside.

As far as I can follow their terminology and the photos available, the 'time and speed controller' supplied with the KP01/KP02 motor/gearbox/prop/battery/controller combinations, #7 and #9 on their product list labelled 'KP 01/02 LiPo + Accessories', appears from the website photos to be different from the 'Brushed motor time and speed controller 10A' (item #120) I have in front of me. I don't have the former so I can't be certain. The product description for KP01/02 states, "The 'with accessories' option includes a single li-poly cell and our low voltage protection brushed time and speed controller", so I would conclude those controllers are for use with 1S LiPo's only.

However, item #120 'Brushed motor time and speed controller 10A' is rated for 1S or 2S LiPo's but doesn't as far as I can make out include a low-voltage motor cut-off. To do so would require quite sophisticated circuitry to detect the number of cells when they are initially connected, store that information, set a cut-off voltage parameter, etc. Most battery chargers do this; I can't see any mention of such in the KP instructions. A bit remiss because at best, the user might or could ruin their batteries by over-discharging them. The design perhaps relies on the timer feature switching off the motor after the run and decay periods. I've scanned the relevant instructions below.

The KP 'Time And Speed Electronic Regulator 35 Sec/120 sec/ 10min' controllers, items #112/113/114 respectively in the price list are used in conjunction with an ESC in place of a radio control setup. That's quite a clever idea because it offers almost complete freedom to time and control any electric model's electric motor/s. This timer/controller doesn't limit the power you want to use nor constrain flexibility of motor/ESC/prop choice, it simply provides a control signal to the motor via a conventional ESC.

HTH, although I doubt it!
Nigel

[AllanP]

A new one, still being developed but very near completion is the 'Tempo' flight profiler. It is a two part system, a flight profiler in the plane and an app on one's phone that is used to adjust the settings - no presets or access required. The settings are all sent by Bluetooth when the start button is pressed,so no fiddling about at the start of a flight.

I did try it at last years' IIFI but it wasn't really ready, and was far too rushed. It was accepted by the judges.

One of the big problems with indoor electric models is the effects ot the state of battery charge. This uses an algorithm to adjust the power as the battery discharges to maintain  consistent flights.

It looks complex in the photos - lots of wires. These are mostly optional to allow external on & off, led, safety link, etc without having to directly access the device.

With any luck it should be ready, and available for anyone who wants one, in a couple of weeks or so.

[g_kandylakis]

Hi Allan,

nice to read about this!

A few questions and comments.

What is the expected weight of the unit when finished?
Size of the board seems about 3,5x2cm, right?
Brushed motor operation only or brushless as well?

If I understand it correctly, you press start on the phone and all settings are transferred to the profiler, so there is no more communication with the app during the flight?

This would be described as a 4-stage timer, right?
Take-off, climb, cruise, descent. (leaving idle out...)

And any idea about the cost?

If there is no signal exchange after the start button is pushed, then I see no reason at all why it would not be accepted as an alternative profiler by judges in IIFI or BMFA competition. It is certainly more precise to input power and time values digitally than by rotating tiny pots.

George

[AllanP]

Hi George,

Thanks! In answer to your questions...

The unit as shown is about 4 gms.

The PCB is 34 x 19mm. Height is about 6mm. Some of the wires are optional, depending on the installation.

This version is for brushed motors using 1S lipo, up to 5 amps, and is aimed at indoor use. There's another version, aimed at outdoor flying, for driving an external ESC for 2S upwards for either brushed or brushless. Driving an external ESC means no upper limit on voltage or power.

Yes, that's correct. When you press the start button all the settings are sent and cannot be changed until the flight ends. There is an Emergency Stop on the phone, so this will send a stop command if pressed. I'll get a better picture of the screen for you.

Yes, but has landing as well, which might be helpful making a flair just before touchdown. Settings for each flight phase are in percentage power in 1% steps, duration of transition from last phase to next 'Ramp' in seconds, and duration of the remainder of that phase in seconds. This means very precise control of each phase. The 'Ramp' effectively eliminates the kick that effects trim when changing power level.
Another advantage is trimming can be done in baby steps.

Several model memories are available, like standard RC practice. Also one unit is bound to one phone, a bit like standard RC.

Cost would be around 85 UKP / Euro. To be confirmed. A website with full instructions, Youtube links, etc is under construction.