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NOTE - FMS connections for the new version 4CH TX have been added below.
              
New Electrafun XP model for FMS sim !  A reader of the blog has made this model for anyone to practice on. Follow the link to the file.
http://www.box.net/shared/87dvbz1249

August 2004
ElectraFun mods:  Add a socket to run the TX with FMS flight simulator !
I did some modification work for my brother in-law on his Electrafun. He's trying out electric R/C with a newly bought ElectraFun complete kit. A cheap way for him to start, cheaper to fix too after the inevitable crashes !
Since we have had a long run of very windy weather we decided to see if it could be used with an R/C simulator for PC like the freeware FMS 2. Well it can.

To do it you need to have FMS RC simulator software installed on your PC, then also have a suitable TX to PC interface. Either build one, or buy a ready made one from off the WWW.  I made mine (and now one for the brother in-law) from the details on the WWW here.

Here are some photos of where you attach signal wires from the PCB to a headphone socket. Then all you need is the standard PIC Serial Interface, it may work on other interface types too. If you have the technical skills, then the photos should be all you need in the way of info. I did put a 100ohm resistor in series with the PPM signal just in case someone decides to plug in real headphones or something silly, to protect the TX circuit. Click on the photos to see more detail.

         

The enlargement of the middle photo has pointers to the correct PCB pads for normal PPM and also an cleaner shaped Inverted PPM. The FMS PIC serial interface seems to work well with either, I guess it automatically sorts out the logic levels.
I also did the well documented variable throttle control mod to his radio transmitter, published by RCM News RC magazine (a very good read). I used a 10k linear pot and a 20K series resistor in place of R31, this worked very well and the normal switch will still act as a fast throttle kill.
One last thing, you can pull out the TX crystal while using the sim, it saves about 66% of battery load ! The TX should run for hours.

Another ElectraFun mod.
I did not like the lack of control response in slow flight  and in higher wind, so I modified a set of tail feathers by cutting the trailing edge back 2mm to make it square then gluing an taping on strips of 2mm Corex. This does make low speed handling a little more predictable now, probably makes it more agile too but I'll need to try it out on a calmer day.

Nov 2005
Many local fliers  have done this mod to their Electrafuns now and on Venom FREEDOM as well, which use a similar tail arrangement.
 
The tail mods have transformed the flying of the Electrafun and Freedom into a more aerobatic capable and high wind model, BUT (a big but) more skill is required now because the model will flick in to a spin very easily if you give it full up and hard rudder simultaneously. It will recover just as easy, but if you are a novice and panic it will spiral all the way to the ground, you MUST release UP elevator to snap it out again. That said, I think the mods just great if you have got a little bored of the stock handling. My pals here can now snap rolls and tight loops with it whenever they like.



And yet another mod.
I didn't like the short transmitter sticks that came with the model's TX, they felt short and odd after my year with a Hitec Flash 5 TX.
Looking at them, the easiest way to fix it was to drive a 3mm tap down the center of the (hollow) stick for about  10mm, then screw in a 3mm hex cap screw and a lock nut. Done, and adjustable too.



Brushless Electrafuns
A lot of guys have upgraded the Electrafun and Freedoms to brushless power with great results. Most are using between 1500kv to 2000kv in long or short type brushless speed 400's. All on 3S Lipos.
They run well with the Align 400S series in 1500kv on a GWS 7x6 prop, or with a 2000kv Himark 400 on a 6x5 prop for great high speeds.
 
The downside is that wing failure is inevitable, usually when the first full power loop is tried.
To fix this we have been taping down a 3mm x 1mm carbon fiber strip across the top of the wing. One is usually enough, but some have used an extra one below the wing as well. They don't fail anymore.

I've found a problem on some Electrafuns with the fit of the wing to the fuselage. The wings can be a little wide on the chord width. To fix this I've taken a sharp file to the tie down plate on the back of the wing, and filed away just enough to make the wing sit properly on the fuse. Bad fitting wings can pop up on the back or front edge during flight and make the model unstable.

JAN 2006
I recently helped out a new RC pilot to set up his Electrafun for it's first outing. It's worth mentioning that the current new stocks of Electrafun XP kits now come with a better charger and transmitter, making the model even better value in my opinion.
The new charger replaced the original clockwork units, which did fail at times and trash the battery pack (melted it due to over-charge). This new charger is a basic Peak-Detect type, and this is a much better system for safety reasons and also able to top up a partially charged pack properly.

The transmitter has changed too. It now has FULLY PROPORTIONAL motor speed control instead of the original on-off switch on channel three. So you don't need to do the volume-knob style modification now. Also the transmitter is a full 4 CHANNELS, it has full directional movement on both sticks. This means the transmitter and all the electronics in the plane can more easily be re-used in a new model if desired (why the hell not !). The new plane could be a fully 4 channel model like a GWS E-starter, Mustang or similar with moving rudder and ailerons.  Just plug in another servo (which are PF-09 type !)



Lastly as an extra bonus the transmitter sticks are now adjustable in length (there goes my other mod !).  It also has the servo reversing switches on the front panel now.

Happy buying.....

July 2006
FMS simulator with the new TX
The new version transmitter is uses a different circuit board to the original. The TX can still be used with FMS via the interface cable but the pin position to obtain the correct PPM signal is different of course.
I found it on the new PCB without much trouble (at first). Initially it looked like I could use a spare pad position that looks like it's there for a factory fitted simulator socket. BUT, although it worked fine with MY home made FMS PIC interface it did NOT WORK with the ALIGN brand FMS cable they sell. After a bit more testing it appears that the factory made ALIGN PIC interface cable did not like the logic polarity of the signal at the pad "P" in the picture.
I traced back the signal until I found an inverted PMM signal on the previous transistor in the chain, this one idles at +5 Volts and the PPM pulses drive Low. Point "P" on the circuit board idles at 0V and drives High with the PPM signals. The ALIGN brand cable works fine on the marked location marked in Yellow, so does the home made PIC cable . So I think that is the best point to tap off the signal for FMS.  Put your signal wire to the Yellow marked pad between one side of R1 and C1 where they connect. The ground or shield side of your simulator cable goes anywhere to ground on the PCB. There are many choices including the spare pad "G" in the middle of the PCB to the left of pad "P", but I used the grounded pin of the PPM transistor marked in Blue above the C1 text. The pin below is fine too as they are both on that same copper trace. I used a 100ohm resistor at the socket center connection to protect the PCB from short circuits when you plug in the simulator cable, you can see it in the first photo on the back of the 3.5mm mono earphone socket.

                 

Lastly, the ALIGN branded FMS interface cable uses 9600 baud data speed, not 19200 like the home made one. Other than that it works just the same. Get into FMS's Controls menu and pick Analogue Controls, Select SERIAL PIC INTERFACE  in the Resources window, also select 9600b and your comm port number (usually 1). Then run the Calibration routines in the Mapping/Calibration window. Setting the mapping is required, to get the TX sticks to move the right control on the model, and in the right direction.

Extra note: With the Align FMS cable with the Futaba plug, the ground connection is to the metal shield not the center pin like for Hitec TX's.

June 2007
A reader (Pijuvwy from RCGroups)  has made an FMS model for the Electrafun XP. Here is the link below.
It flies just like the real one, but change the rudder on FMS to Ch1 for Mode 1 training.
Electrafun XP for FMS


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