Dirty, I have not used A123 batteries and honestly was expecting the voltage drop to be on par with Nickel Metals. Perhaps I will give them a consideration. I still think that long leads can be an issue. Yes it does depend on what RF is floating around in the enviroment and at what power level. When I was more competitive in IMAC I would attend 3 to 4 contests in Las Vegas. Both at the Bennet field and North Vegas. That region has a reputation for a very high noise floor. There are several military installations in the area and we can only guess what they were transmitting. At that time I was equipping my 40% models with a Smart Fly Power Expander and Turbo Reg. Yes regulators do burn capacity and I do recomend to guys adding regulators to up the battery capacity at least 20% The airplane had 13 JR 8411 servos and yes Ihave flown a sequence that had a double positive snap roll in the center of a long downline. All 13 servos are loaded in this case and the airplane is traveling approx 60 mph. JR would never admit it but being the first really high powered FET sevos available for airplanes, they were qutie noisey. Current draw had to be pretty high. With this setup I never had issues in what I would call a dirty enviroment. Obviously there is no real wrong answers with this stuff as there are many variables. For me what is safest is to err on the overkill side and fly with 100% confidence and concentrate on flying and not if the airplane is going to continue to listen or not. Funny you mention RADAR, I am a little aware of what that can do as I currently work on the E2D program.

Funny you should mention the E2D program. I spent many years as a test engineer on the E3A program for Boeing.
Get yourself a spectrum analyzer and measure the noise floor at those locations in Vegas. Be careful not to aim your antenna at the horizon. Aim it straight up. I bet you will find the noise floor is no different from anywhere else in the US.
While testing servos for a magazine article, ( have been retired since 2001) I found the 8411 and the 8611 not great at producing loaded torque. Although the no load deadband was very good, they did not produce well when loaded. If you change to the Hitec 5955 or later servo you will notice an improvement. That is if you don't spoil it with a large negative expo setting.
The JR servos just had a poor torque vs error signal curve. I have not tested their servos later than the 8611.
The A123 batteries start at 3.3V with no load and drop to 2.7V at 40 amp load. That regulation would be hard to match with a regulator.

That is funny. we are currently going through qualifications for new AWACS elements. I built up a set a few weeks ago.

Speed,

Let me suggest that you look up Tech Aero Designs IBECs and VRegs. These are excellent products. The designer understands filtering. Sure the current 2.4 gig stuff is nearly immune to CDI RFI but this particular IBEC was designed with 20-25 year old radios as test beds. I think we tested about a dozen radios.... the major 4 manufacturers were represented

Matt, thanks I will give them a look. Although I am no engineer I do have direct access to several microwave engineers that have been developing antennas, elements, emitters and such for 30+ years. I have shown a couple of them the interior of a few airplanes and the equipment we use. Both of them strongly suggest that I continue to seperate equipment even with 2.4. I have compete confidence in these gentelmen and am learning more then I originally bargined for. Not that I would ever discount the opinions of guys such as yourself but these are guys that have designed E2C, E2D, AWACS radomes along with antennas mounted in everything from F-15's to B2's.

It just makes common sense to keep radio equipment of any kind separate from a spark producing unit.
That said though, I have tested an ignition system setting right next to a 2.4 system and found it did not affect it. I did this because I read somewhere a spark system does not bother RF systems above 300MHZ contrary to theory. I decided to test it.
Your friends are probably great engineers but I bet they have not worked with the specific equipment we use and therefore will give you a generalized(Safe) answer.
When a spark occurs it shorts out the applied voltage and converts a nice sign wave into a square wave. A square wave is defined as possessing an infinite number of odd harmonics. That would say that all radios would be affected but they are not. I suspect that the resistance of the wires limit the rise time of the square wave to less than 300 mhz. We can limit the rise time to the point that we will not affect a 72mhz system by putting a resistor in the spark plug.

I 'm no fan (excuse the pun) of a regulator and powerbox set up either. Its just unnecessary weight and complexity. Proper servo set will eliminate servo'sfightign each other on multi servo wings. COnstant voltage feedof A123's also goes a long way.
But on the ignition, I'm not aware of any voltage requirements changes that puts a regulator at a disadvantage other than it being an electronic device that can fail. I'll still use a LiFe n a dioe though