Free flight electric

[boffin]

If you want a FF sport profiler with a bit more capability, than look to the Atomic Workshop site and play around with the Zombie. This 1.8 gm profiler is micro processor controlled having an integral brushed 4 amp ESC and provides:-

1. A 0-14 sec 'wait' time to place the model on the floor for ROG.
2. A variable motor idle time
3. An adjustable take off power of X1% for Y1 secs
4. A cruise power of X2% for Y2 secs.
5. A LED output which changes colour with battery voltage to signal battery low.
6. Motor drive current is pwm'd and not potential divided thru a resistor.

The graphic shows this system set up in a 17" span 43 gm Frog Senior series Tomtit with a Voodoo 15, single cell 90 mah LiPo and GWS 5 x 3. The second graphic shows the Zombie with the 4 'tweaking' pots for motor power and time.

The system is a FF sport alternative to the Pboro timer, though at some cost.  It was suggested by Pete M on the 5th June in this thread. Primarily intended for indoor FF and micro RC, but ought to fly outdoor on calm days.

Feb 7th
This model has now flown well indoors at Oundle School running a 30 sec climb, 20 sec cruise and landing on its feet unscathed. With the power  settings turned up a tad, it has flown for 90 secs at Ferry Meadows on a windless day, landing 20 feet short of Ham Lake. This profiler is a credit to its designer, Richard Crossley, and a delight to re-program.

Regards, Ian

[Bretty]

The Tomtit looks very pretty and extremely well made.  Unbelievable what is possible now in such small packages    I recently watched my son hovering a tiny indoor electric helicopter in and out of the wine glasses... and thence to a gentle landing on his hand - simply unbelievable.

Andy

[boffin]

Gentlemen,

Yet another free flight scheduler..............................

Previous posts in this thread have identified the Pboro MOSFET timer and the Atomic Workshop Zombie for free flight scheduling of brushed motors such as the Voodoo, Falcon PU series and GWS IPS. The following note shows that it is possible to adapt the current breed of cheap, light, efficient brushless motors for free flight sport and to use high energy density LiPo batteries with the ESC providing safety shut down for current high and voltage low.

The problem with brushless motors for free flight is that the ESC (speed controller) demands a signal from the RX to set current demand. To get around this, a PIC chip microprocessor was used to fool the ESC that it is connected to an RC RX. It is possible to program the controller for motor power and  motor run time. In addition it provides a timed DT siganl to an auxiliary lightweight servo.

[Spadge]

Hello Boffin.  Have just registered and seen this discussion.  I was looking for a method of controlling brushless motors for FF.  I came across some information from Dave Day's website which is really about control line flying.  In his links there is something called "JMP timer".  I have emailed JMP (Jean-Marie Piednoir) a couple of times and he has produced a unit that does as you list but with one or two other functions thrown in.  I tried to buy one at about 25Euros but never got replies to my emails after the first reply! I will monitor your progress on this matter.

[boffin]

Due to apparent lack of interest, I will desist from posting any futher on this topic but will close with some data that determines the power required to fly free flight brushless electric models as a function of all up weight . The data is based on static tests on 5 models ranging from an 18 oz cabin Hornet to a 6 oz Slicker 32, using a standard commercial watt meter. All models are set up with a FlytProf scheduler with pulse width control of current draw.

The conclusions are .........

1. The power required is minimal, 1.5-3 amps for a decent climb on 2 cell LiPo.
2. This is 20-40% of the ESC/motor rated capability.
3. The electrical power is linearly related to total model weight.


Regards , Ian

[richard]

Hi Ian,

This post has had over 1000 views, it's one of the most popular threads on the site!

Remember that the majority of people who view this site never post, so don't worry about lack of feedback.

[boffin]

Gentlemen,

One last post on this thread to complete the timer subject.  I did promise to stop posting but the FlytProf controller software has been extended to give four flight phases and, to my knowledge, now offers unique functionality, so worth telling you all what it does.

The four phase FlytProf was muted by a regular FF Nationals Scale competitor who has used a single phase FlytProf at the 2007 Nats and wanted more from the controller. He asked for, and got separate motor power and time  runs for ROG, climbout, cruise and land with an 'auxiliary' function to change the trim of a surface to allow for the change in power output.

[JayeM]

Ian,
can I just say how much I've learned from reading your "boffin" posts - the topics may be routine for you "old hats" at FF, but some of us have lots to get up to date with after 30-odd years away!

As Richard said, just because we don't reply doesn't mean we're not enjoying and learning 

keep up the good work - I look forward to more posts from Boffin in the future!

Cheers,
John

[CHE]

Sir Boffin,

Your timer is very interesting and a logical development. It's great to see FF scale guys now thinking of more things to do now with their models now that practical electric flight with control is available. It's kind of like what happened in FF duration when electronic timers got programmable. I expect to see a step change in FF scale activity in a similar manner to the indoor foam scale development of the past years. Please keep us all informed of how this device is used. Fascinating !

[boffin]

JayeM aka John,

Thanks for your kind words but you are not correct in assuming that this is 'Old Hat'. Like you I have re-started modelling 2 yrs ago on retirement after a pressure of work induced layoff. I was immediately impressed with the developments in electric componentry but felt that there was some scope for further improvement in FF sport timers for electric power units in the 10-30Watt range.

Believe me , as a mechanical engineer , I am struggling with the technology and what you read is the bits that have worked and I do not tell you about the smoke fairy visits, the grand mess ups or the rubber driveshaft that oscillated like mad.

So please post if you have any different ideas or experiences as I can use all the help I can get on the timer subject.

Regards Ian

[boffin]

I thought I would run a very quick review of the PICAXE system and how it can be easily configured as a free flight motor run timer for either brushed or brushless motors.

The PICAXE is a microprocessor chip which can be thought of as having its own compiler on board. To programme it, you can write in a simple language such as BASIC and then send the code down the PC USB port to communicate via a serial link on the board. Total cost of the board is a few pounds. The downside of the system is that it is not surface mount so that 15gms for an 8 pin controller is about the going rate.

[JefO]

Ian

For the past few weeks I have been looking intensely for fields (for holding F6D events) and have stumbled across an absolute gem for free-flight, and particularly electric freeflight.

So when I have done with Rockets, I will refer back to this thread before starting any new projects.

The ability to control multiple surfaces and motors on a freeflight scale model certainly captures my imagination - many thanks for the work on assessing PICAXE. How complicated can we make the simplest format?

Jef

[boffin]

Gentlemen,

A  modelling friend has successfully developed yet another free flight controller using the Picaxe system. The investment, from a cold start, was 4 weeks of spare time and the cost of the components for the controller would be approximately £4.

The system controls the power of a brushless outrunner on 2 cell LiPo for 3 flight phases and modifies rudder (or other trim surface) dependent on motor power. All variables are capable of being modified by the user and a DT service is offered.

[freeflightguy]

Also check out www.electricfreeflight.com for motors,timers ect. and gives diccounts to AMA and NFFS members......check it out

[boffin]

Freeflightguy,

This site features 2 timers...............

The first is a 555 chip based analogue device intended primarily for the US E36 discipline. It caters for brushed motors only and uses a trim pot setting method for varying the motor run time. Surprisingly, the timer does not have a DT facility.
FliteHook have imported a few......ask for the Stew Myers timer.

The second timer is an alleged F1Q device being  a digital Zigras Ztron run from a PIC chip. The timer graphic shown is actually for control line use but Zigras does market a FF timer of similar layout. The timer output is a logic level signal for input to an ESC controlled brushless motor and a servo driven DT. The timer is reprogrammed using a DIP switch array. This timer is conceptually similar to the UK FlytProf but does not have any audio output.

Regards Ian