RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Set Up Question:

OK Chaps, I'm coming down the home stretch and I need some advice. I have two heavy duty switches built in with hatches for battery and ignition and I don not want to add another hatch so can I get away with one switch on my batts? I was planning on two 2000 MAH nicads, can I "Y them into the rx? I heard if I do and one goes bad it drains the other. Help needed, I want to fly my spit this summer. Cheers.

Moggy

PS: I don't want to get involved with voltage regulators/ lipos/123 and that lot with a warbird. KISS

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

one on the normal BATT ch and put the other on a spare ch if you have one. The voltage rail in most RXrs is a common bus arrangement s oa spare ch is suitable.

Dont like batts on Y leads personally as it then becomes a single source of failure

All I ever do is 2 batss, 2 switches and plug into the RX as I have described.

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Pete

Does each batt need its own switch? I only have one switch dedicated for rx batt the other is for ignition. Cheers

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

I would

if anything is going to fail it is the switch and dont use those puny standard ones, they are only rated at 1/2 amp, you need a heavy duty switch such as a JR G or D type. think they are 5 amp rated.

name of the game is redundancy

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

You might loook at Madison Components switches. They make a Dual rocker switch in one frame.
http://www.qualityrcproducts.com/prod_superrocker.html
I have beeen using them for years and I think they are a good switch. The flashing LED feature has saved me from leaving a radio on more than once and you can put it in the cockpit out of sight

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Moggy, usually two batteries for the RX means two switches. As I know the only way to use two batteries with one switch would be to 'Y' lead as Peter says and what you have been told is true in the fact that if one cell goes down then it will drag the rest down as well. Now, if your RX was in the cockpit and fully accessible you could plug the second battery straight into any spare port when you wanted to fly but that is pretty impracticable.
That double switch from Madison Components looks pretty cool JL1.

Brad

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Moggy - the two switch set up is explained here [link]http://www.hangtimes.com/parallel_packs.html[/link]

I've used this same set up for a few years, no problems. If you do not have an spare channel opening in your rx then the second battery lead in gets y ed in with the flap channel or which ever channel you want to choose.
I've been using the JR HD switches or the MPI HD switch assembly.

good luck.
-ken
.

http://www.hangtimes.com/sitebuilder...rallelbatt.jpg

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Another thing to consider is that by having both switches (ignition and rx) in the same switch access panel the wires might be so close together as to introduce some interference with the radio. I'd recommend keeping the ignition components up front if possible. There are some smaller access panels on the cowlings of Spits.
Sam

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

JL1

The duel rocker switch runs two batteries off one switch? What if the switch fails, then I'm toast, right?

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

They are supposed to be (and I have been assured by the distributer) two seperate sets of contacts. It is a double throw, single pole switch.
Talk to them, they will explain it to you. My contacts with them have been positive

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

I would not claim to know much about i ,t but if the receiver has a comon bus bar , would the battery draiing thing still apply just through the receiver .is there a solusion to this problem or is it not really a problem . and let me just wish you all a happy christmas and good new year.  

John. 

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

For what it's worth...

Most battery failures result in a shorted cell. Running to pacs in parallel without some form of isolation will reult in the good pac being dragged down and possibly losing your model. Running pacs in parallel does not increase you reliabilty, it Decreases it. For increased reliability you will need a commerical duel pac battery isolator and there are many available or make a simple one with a series diode and an extra cell.

Dave

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Here is an excerpt from the information Kenair put out:

Many pseudo battery "experts" put forth the argument that plugging two battery packs into the same receiver with out blocking diodes is NOT a good thing, claiming that his creates a host of problems and the two packs will end up fighting each other or "cross charging".

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).

cls 5/97

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

That is a good read there Moggy and it enforces my confidence in my set-up as Kenair have illustrated above with duel RX batteries.
Keep it simple Simon:) the less components the less likely of a failure,,,,, of course quality of product comes into the equation. Good quality batteries and switches are a good and easy start.

Good to know you have made almost finished your Spitty, any pictures??

Cheers,

Brad

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Hi Moggy, if your using or up for trying J.R/ Spectrum gear I would reccommend the AR9100 DSM2 9-Channel PowerSafe Receiver which is set up for 2 batteries but one switch straigh to the rx. In the chance of switch failer the system is designed to lock in the ON position if the switch dies. It has 3 remote antennas and room for a 4th to ensure good signal strength. If your not using 2.4 then forget everything I just said. Cheers Trent.

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Another thing you might consider are batteries from these guys
http://www.hangtimes.com/
I have no business or personal connection, I have just used their nicads for several years and have had very good luck with them.
Besides there is quite a bit of battery info there.
Merry Christmas

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Good stuff guys, it's what makes this forum great. Pics will come after new year, of course nothing compares to Brad and Nudges work. Merry Christmas to all of you!

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Two battery packs through two separate switches into two ports on the receiver is the way to go. The idea that using two battery packs through two switches into two ports on a receiver is bad because if a cell in one of the pack fails that it will drain the other pack has been proven incorrect on numerous occasions.

There are two failure modes for a pack: 1) a contact or connection fails creating an open circuit for that pack; and 2) the separator of an individual cell in a pack fails, causing a short in that cell of that pack. The first failure mode is not an issue. The pack with the open circuit has no effect on the other battery pack delivering current to the receiverit is as if the pack with the open circuit was not connected. In the second failure mode, the voltage of the first pack drops from a nominal 6 volts (assuming a five cell pack) to 4.8 volts. The second pack remains at 6 volts. So now there are two packs connected to the receiver at different voltages. Will the pack at 4.8 volts tend to drain the pack at 6 volts? Yes, theoretically, although numerous tests have shown the drain to be about 1% per hour. Several of these have been documented here on RC Universe. This condition is very easy to detect by doing a simple loaded voltage checks between flights, as I am sure everyone is doing. Battery backup circuits and diodes can be used, but with added complexity and cost and additional failure points.

-Ed B.

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Oh Moggy thanks man. Yes, Merry Christmas to you all guys. I hope you get lots of (model) presents and also think of those who are less fortunate than ourselves.
Peace on Earth men.

Now, I've been a bit quiet lately with being away, being injured (pinched nerve in back) , work and motivation so I am happy to report a little progress with the canopy. I have finally shaped and glued in some spring wire to the front inner bubble canopy frame that will hold the assembly into the rails via the tabs I have fitted. I covered some piano wire with heat shrink as per Leo's instructions (quite a few pages back) and epoxied it under the frame and then did a thickened fillet to ensure it stayed in place and make it look a bit tidier. I now have to pull the canopy apart a little to mount it into the rails and with the lip at the front that sits under the front windscreen frame this should ensure it doesn't fly off during my high speed passes:) I am yet to glue the rare earth magnets to the rear but that is the next step. The final fit is a bit off but when I get the courage to do some final bending I might be able to tidy it up a bit.
With the fuselage access panel I picked the side that stuck out a little and glued the magnet to that side so I will end up with a snuggly seated door. Just have to glue in its mate inside the hatch.
I will hopefully do a bit to the exhaust over the Christmas break and get it all welded up early in the new year. Almost there.

Cheers,

Brad

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Good job Brad!

can you tell me why the shrink tube on the wire? for esthetics or for some other reason?

Thanks,
V.

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

OK you Spitfire fanatics, Santa came early to my house and left me an extra book titled: Spitfire The History by Eric B. Morgan and Edward Shacklady. Rather than send it back I am offering to anyone who might enjoy the book. Jeffrey Quill describes it, "As definitive a history of the Spitfire as is ever likley to be written." The book is out of print and in Very Good condition complete with dust jacket. I am only asking what I paid for it ($80 plus actual shipping). Some of these books are going for over $200USD. PM me if interested. The book has every nut and bolt in every mark of Spitfire.

Moggy

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Vas, I would say the epoxy would lock onto it better than shiny steel wire. Thats the only thing I can think of. The whole inner frame will be painted interior green when done.

Cheers,

Brad

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Hi Guys
Just like to say happy Xmas and New Year to you all.

cheers Nudge

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Hi Nudger

We're a bit ahead of you and already enjoying the day :). Hope you enjoy yours and happy building and flying for the New Year. I bought Richard a 1/4 scale Comp ARF Spitfire, it's actually 1:4.5 scale so will now have to make the pilot to fit that properly.

cheers
Patti

RE: The complete YELLOW AIRCRAFT SPITFIRE thread.
 

Hi Patti
Great plane you chose,that is on my list to build when i get the spit done.Doing the correct size pilot for that mustang is much needed and sure will be a hit.[sm=thumbs_up.gif]

Cheers nudge