Here is a list of all the postings Rich too has made in our forums. Click on a thread name to jump to the thread.
|Thread: Glens Models 25% Sukhoi - manual anyone?|
It’s taken ages as usual!
Nearly there now. Ran the motor at the weekend and it ran a treat after a plug swap. Not bad considering it hadn’t run for over ten years
John, do you remember if yours had the cowl baffled for cooling? This one hasn’t so I am wondering whether it needs it.
other than that, just balance set the throws and then the maiden beckons....
Edited By Rich too on 17/09/2019 21:00:23
|Thread: SLEC Chipmunk build blog|
I do love the Chipmunk
Edited By Rich too on 17/09/2019 20:56:11
|Thread: Repair of a Hanger 9 P-51 Mustang.|
i’m hoping to be inspired to sort out the u/c on my Thunderbolt.
|Thread: Glenns models cap 232|
I would also add that twin batteries become a lot more popular as a way to isolate the ignition systems, but with 2.4 radio it is no longer an issue. We probably do not need to use twin batteries at all......
I believe the point of the article was that the chances of a short are very slim and other equipment failure is more likely. A short is more likely in the event of a crash. And LiFe batteries are very robust, that’s why I use them.
Each to their own
These concerns show a lack in the understanding of the charge and discharge potentials involved in Ni-Cd cells. One pack cannot charge the another (equal number of cells) as the discharge voltage of a pack can never be as high as the voltage required to charge the other pack. For the doubters here is an experiment: completely discharged one pack to 4.0 volts and then connected to a fully charged pack having an equal number of cells. There will be less than a 10% transfer of charge in a 24 hour period. Since shorts rarely occur in fully charged packs the risk of one pack "dumping" into one with a shorted cell are insignificant. A simple ESE preflight test would detect a pack with a shorted cell.
While it is a fact that the typical failure mode of a battery is for a cell to fail shorted there are some subtleties here that escape many people. First,one of the major causes of "battery" failure has nothing to do with the batteries themselves but rather with a switch or connector in the battery circuit. The dual redundancy concept is to protect against the failure having the highest probability - that being the circuit path from the battery to the power buss in the receiver. Adding more components to this path, like regulators and/or diodes isn't going to help the matter but rather adds to the probability of failure.
Perhaps the following discussion on the nature of shorts will better help the modeler understand.
While it is agreed that shorts are the failure mode in Ni-Cds batteries one has to look further into the "when" of the failure.
A short develops in a Ni-Cd when conductive particulate bridge the separator or the separator itself deteriorates to the point where it allows the positive and negative plates to touch. Rarely does the short occur all at once but rather building up a very small conductance path termed "soft shorts". In a charged cell the energy in the cell will blow away any short as it tries to develop. You've heard about "zapping" cells. The cell actually zaps itself before the short can develop. Only in cases of severe overcharge at high rates can the separator melt down to the point where the plates contact each other (hard short). In this case the energy in the cell then dumps and we have what is referred to as a hot steamer, the electrolyte boils, nylon in the separator melts down and is forced by the steam through the vent. On some occasions the vent is clogged by the molten nylon separator and becomes inoperative causing the cell to rapidly disassemble. So under normal circumstances a cell maintained at some state of charge is much less likely to short than a cell that is completely discharged. It should be noted however that the self discharge increases rapidly in cells where there is a short building (high resistance -soft short) due to separator deterioration and/or cadmium migration. One other shorting mechanism is a manufacturing defect where the positive or negative collector tab bridges the opposite plate. These usually fall out before the cells are shipped or assembled into batteries.
Preflight procedure should involve checking each battery separately. First check each with ESV through charge jack. You should get nearly identical readings, then switch one on, check controls, switch off and then switch on the other battery, check controls again, then turn both systems on and fly with confidence.
Summary: Diodes are not required. Packs must be of the same number of cells. Packs may be of different capacities. Individual charge jacks must be provided for each pack (and not interconnected). Total capacity available will be the sum of the individual capacities. Specialized chargers are not required since standard packs (600-800 mAh AA packs)can be charged employing regular system wall chargers (1200 to 1600 mAh should cover most giant size projects).
Each to their own, but I've done my research - I like to keep things simple and reliable.
I've had switches fail so now I tend to use electronic ones that fail ON.
Edited By Rich too on 14/09/2019 10:53:44
Edited By Rich too on 14/09/2019 10:54:33
As I understand it, that is highly unlikely. All my planes have twin battery set ups, and i've never had an issue.
No need to remove it
The batteries can always share any of the ports. I've put twin batteries/switches on a Y lead in the past.
Edited By Rich too on 13/09/2019 06:38:08
|Thread: Well this could get interesting|
This is unbelievable, and of course Steve, they have the right to protest - within the law.
|Thread: Drones planned in Heathrow expansion protest|
Apologies, missed it. Can a mod please close this...thanks
|Thread: Southern Model Show 2019|
They require no assembly and are a fit and forget item. Some petrol flyers strip down there tanks each season to check the fuel lines!
Nice one Rob and a man after my own heart - you've given me some optimism!
|Thread: Southern Model Show 2019|
Yes, i went on Sunday and had a great day. It was our third trip there but not been for a couple of years. I thought it was the best one. I think the good weather helped. I’ll be going again.
ps the oval car racing was brilliant. Those cars can take some abuse!
pps and I picked up two brand new Rotoflow fuel tanks for £10 each! One was 40oz for my Sbach, and the other 14 oz.
Edited By Rich too on 09/09/2019 18:16:59
|Thread: Glenns models cap 232|
Nice looking model
|Thread: Shortage of 35% (100cc) aerobatic kits in the U.K.|
Should be I would have thought.
Edited By Rich too on 07/09/2019 22:46:46
Excellent Adrian, which is your preference? Look forward to the build....
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