Be sure to detail your electric gear. I have wanted to try electric free flight for years but just don't have the knowledge.
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)... ;D
Of course you can make a whole science topic about it, but from my experience best is to just start.
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 ΓΈ8,5mm 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.
- 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.
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 ;D , 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.
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.
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.
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.
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.
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.
Quote from: g_kandylakis on Feb 14, 2026, 02:42 AMThere 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
This is part of a longer( :o ) 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
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.
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
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.
Thanks Alan...
One other aspect I forgot to mention in the beginning of this profiler discussion, is availability for purchasing.
I am not sure if the Zombie and K&P are indeed available, there was some shortage at some pointwith the Zombie, if anyone can confirm, please do.
The one I know is available, is the Chronos by Jiri Dolezel which was on sale at IIFI 2025 and apparently soon this one by Alan.
Erik Crins is working on something as well, initially for himself, I do not know if it will be made available to others too. Still waiting to see his presentation, hopefully soon.
George
We expect it to be available in the next couple of weeks or so.
I must hastily observe that this is a collaborative effort and by no means all my own work. The software and App have been written by Dave, who's details I'll share when I've checked with him that its OK to do so. He has also produced the brushless version for an external ESC.
My role has been on the seemingly endless testing and reporting back, and for the schematic & PCB design.
Hi,
I'm Dave, collaborating with Allan on the Tempo flight profiler, and I hope that it'll be of interest.
Allan has described the version that he is working on, intended for 1s batteries driving a brushed motor. This turned out to be a bit more complex than the version that I had created, which works with brushless motors on 1s, or 2/3s with a BEC equipped ESC. It is NOT suitable for brushed motors on 1s - hence Allan's development - but might work ok on 2s, as you'd have to use a BEC equipped ESC - but I can't see anyone using a 2s/brushed motor system.
The Tempo 'Cardinal' (so called because it first flew aboard a Veron Cardinal) weighs about 2.4g - here's a video of that first flight...
and here is one of Allan, trying out the 1s version indoors...(accursed walls..)
Those timers are amazing.
For a somewhat simpler, somewhat lower tech approach, this thread about capacitors may be of interest:
Supercaps for free flight models (https://www.rcgroups.com/forums/showthread.php?4032135-Supercapacitor-Power-for-FF)
Note that you can charge to lower voltages for shorter flights with less power, or use a lower farad capacitor for shorter flights but the same power.
Sam in the discussion above has a Guillow Skyraider which flies well with a geared motor and supercap: https://www.rcgroups.com/forums/showthread.php?4508439-Supercap-Guillow-s-Skyraider/page2 (https://www.rcgroups.com/forums/showthread.php?4508439-Supercap-Guillow-s-Skyraider/page2)
He also has a 24? inch Taylorcraft he flies indoors. The sonex413 channel on Youtube has a bunch of supercap flying.
If memory serves, there is a discussion on the web of the Peterborough timer and even a version which allows you to walk away before the motor starts. You have to make it yourself from several components, though you don't necessarily need a circuit board.
I'm impressed with how much power can be obtained from physically small capacitors. Years ago, I had a housemate who made an amazingly good stereo. The capacitors on his homemade amps were the size of beer cans.
One vendor who has a bunch if interesting little motors is Micron Wings in Australia. However, I think there are good suppliers in Europe as well. I think the coreless motors are lighter thn KP for their power, although if you need nose weight anyway, maybe it doesn't matter.
I wonder if anyone is doing supercap Ebenezers?
Very nice, Dave and Allan!
That looks like a ESP32, right? That does also do the Wifi connection?
I have thought of something similar, maybe with an ATtiny85. That would of course, not have the comfort of using Wifi for configuration, but maybe be a bit lighter?
Very interesting project!
Cheers
Alex
I've played around with supercap power, and the Peterboro timer, and they're both excellent low tech methods - and it was the sonex youtube channel that got me into supercap power, love the videos there.
The Tempo is based around an ESP32 C3 Supermini. When I first had the idea, I looked for the smallest bluetooth enabled microcontoller - turned out to be the Supermini. IT also has onboard wifi - but this uses a lot more power than the BLE (Bluetooth Low Energy).
I'd already written umpteen Android apps using the wonderful online editor at MIT App Inventor, hence going this route, apologies Apple users - but it still took a long time to get it all working reliably, and I think we've cracked it now - thanks to Allan for doing the testing!
I did think about an ATtiny version to save weight ((I'm more familiar with the Arduino mcu's) - but then you need to somehow get your flight profile from the phone to the mcu in the model...I did think about IR, but few phones have the required IR output.
At the mo, I'm playing with the smaller ESP32C3 mini-1 module, which is lighter than the Supermini - but so far proving to be a headache.
Thanks for the interest, I hope to have the website up soon, cheers.
fascinating - it's great to see experimentation like this happening. here's to all the small time developers and suppliers. :)
Good luck with it.
John
Hi Dave and Allan
Some thoughts triggered by this thread so far:
- I do like the idea of using an app on a mobile phone to input and control the timer. The use of pots and pushbuttons in current alternatives seems pretty clunky.
- I can understand wanting to develop one of an Android/iPhone first. However, when you get a moment to develop the iPhone alternative app, please do so.
- Are you considering just making a DT timer version (i.e. no electric motor control issues)? This looks like a real advance on the BMK system if you do.
- On the subject of DT, I have been wondering about whether a better actuating system that those currently available (band burner or servo) would be the 2 second powering up of a small electromagnet - my idea is that the DT line would have a small magnet the +pole of which attaches to the end of the core of an electromagnet that is usually off. When the timer runs down it will charge up the electromagnet so that the relevant end of the electromagnet becomes the + pole - the two = poles repel each other so the DT line is released. This seems simpler and possibly lighter than the current alternatives.
I really wish that I knew how to create an iphone app - but, personally, have always avoided Apple products and have no knowledge of how to go about it - from the little reading that I have done, it looks to be fairly complicated. If there are any amateur developers out there willing to have a go, I'd welcome the contact.
I did look into an alternative route that uses a WiFi connection, with the flight params entered via a webpage form - which would work on any platform - but using a wifi connection took a lot more power, drawn from the flight battery. The clue's in the name, BLE....
Regarding auxiliary function such as D/T.... the present Tempo Cardinal (the brushless version) does have an extra pin brought out - the idea is to connect a beeper to this and the app has a field to enter a time value - this many minutes after a flight ends, the pin will go high and activate the beeper - but it just as easily be connected to (say) a hot wire D/T - or I might alter the programming to output a servo signal to activate a D/T? Lots of possibilities here, and I thought it best to see what others thought for now.
Gaah...should have thought of this earlier...here's a draft copy of the user guide, which describes the widget in great detail. IT also has the instructions for the kit version - this involves a fairly simple job of soldering some fine wires and should be doable by anyone with a little soldering experience.
Jeremy, Re your point number4. BMK already does a lightweight solenoid for DT and it has had good reviews.
Ron
Quote from: cvasec on Feb 23, 2026, 12:59 PMJeremy, Re your point number4. BMK already does a lightweight solenoid for DT and it has had good reviews.
Ron
Thanks - I had missed that