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It's an airplane question for the RC type.

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mlas(at)cox.net
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Posted: Sat Jun 09, 2007 9:28 am Post subject: It's an airplane question for the RC type.

I was wondering if anyone has any good ideas to solve a Radio Control

receiver problem in the hobby market that has just recently come about.



For years in the Radio Control world (RC) the aircraft have been

controlled with and analog radio receiver on the 72mhz band.  Some new

equipment to recently hit the market is a radio system that uses the

2.4Ghz band with digital processing.  I won't get into to too many of

the details unless someone wants me to.  The new systems were originally

tested with gas or liquid fueled aircraft only which provided a separate

source of power solely for the receivers.  The latest versions of

aircraft that are coming into the marked place are electric (battery)

powered airplanes.  For the last year as these new systems were coming

into the market the first electric airplanes that use this new system

were small park flyers that typically used 3 or 4 small servos that

pulled aprox. 1 amp or less of power from the power bus of the radio

receiver.



The radio system on electric aircraft typically use a motor (brushless)

with a speed control, LiPo battery, servos, and a motor speed control

with power a regulator for the receiver power.  The typical output of

the average speed control to the receiver has been regulated to 4.8

volts with the ability to support about 2 amps.



In the past with the analog systems, as the servos pulled the voltage

down during use, the holding power of the servo would go down but the

receiver would continue to function.  But with the introduction of the

new digital receivers this no longer works.  What has been happening is

when the voltage is pulled below aprox. 3.6 volts the processor in the

receiver shuts down.  The restart time for the processor to re-link is

about 2 seconds.  In most cases this fatal to the aircraft being flown.

The obvious fix would be to provided the receiver with its own power

source but due to weight and power consideration this is not possible or

desirable.



My question, is their any way to provided a method of stabilizing (by

short term storage) the voltage during the transient voltage spikes that

would be easy to build and keep in a very small package and would not be

reliant on the battery voltage going into the speed control?



Mike Larkin



-- 

3:15 PM

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rparigor(at)SUFFOLK.LIB.N
Guest

Posted: Sat Jun 09, 2007 10:08 am Post subject: It's an airplane question for the RC type.

Hello Mike



We made our own BEC for a 16 cell beast a while back. Not very difficult

and incorporated a nice heat sink. For the most part I think that you can

run servos on 6V, although they will draw a little more power. Would this

extra voltage get you over the hump? My gut feeling is you could probably

overdrive both the servos and receiver by a bit more.



Chances are your BEC is too marginal, and can't handle the amps. I havn't

been following too close for some years, but there are BECs sold seperate,

could try one of those.



For the scope of what you are trying to do, you could probably wire your

receiver direct to a portion of your batteries, the draw will slight

discharge those cells, but probably moot. You could put a low head space

regulator to control voltage off the battery pack, in other woerds make a

receiver specific BEC (~6+ volts). You could put a seperate mini battery

for receiver. If it is a parkflier, and cheap and easy is the key, you

could try dropping voltage to your servos, it will drop amp draw, as well

as a bit of servo speed and torque. Your servos also may be throwing some

noise to the receiver that it does not like, also the BEC/ESC combo may be

making some noise, or the motor itself. Best first course is contact the

receiver Mfg. And ask them their opinion on what best to do.



Did you already try antenna repositioning, wrapping the receiver, twisting

servo and receiver leads, wrapping the ESC, does it do it with motor off?,

Can you add another cell to your battery pack?



Ron P.



" My question, is their any way to provided a method of stabilizing (by

 	  Quote: 	
		   short term storage) the voltage during the transient voltage spikes that

 would be easy to build and keep in a very small package and would not be

 reliant on the battery voltage going into the speed control?"

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ktlkrn(at)cox.net
Guest

Posted: Sun Jun 10, 2007 6:44 am Post subject: It's an airplane question for the RC type.

Hey Mike,

  

 We were talking about this last weekend at the  International Hand Launch Glider Festival in San Diego. The key seems to be  getting a speed control with the proper BEC that keeps the voltage at higher  levels. Not sure which one that is but I'm sure someone on RCGroups would have  an answer.

  

 I can tell you the new Futaba 2.4 stuff does not  suffer from the same. Their chip was designed for the purpose. The other stuff  was off the shelf chips that were not designed for power fluctuations. The XPS  system for example uses a chip from wireless routers. That is part of the reason  they are not working well in a variety of environments. The only system that has  work in a very crowded environment is the Futaba stuff. 

  

 I'm holding on to all of my 72 stuff until there is  some milage on the 2.4 equipment. The more that go to 2.4 the less that will be  on 72.

  

 (Mike, give me a call)

  

 Darwin N. Barrie

 Chandler AZ

   [quote][b]

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