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  #11  
Old 02-16-2016, 04:56 PM
Mel's Avatar
Mel Mel is offline
 
Join Date: Mar 2005
Location: Dallas area
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Default

I have dual impulse Slicks and love them.

I use toggle switches and pushbutton start. I have the start switch wired through the "back" side of the avionics master so that the "start" circuit is dissabled with the avionics master on.

I have a locking canopy. If someone wants to steal the airplane, it doesn't take much to cut the "P" leads and be off.

For "my" feelings, the simplicity of the pushbutton start far outweighs the fail mode of "key" switches. YMMV.
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Last edited by Mel : 02-16-2016 at 05:01 PM.
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  #12  
Old 02-16-2016, 05:47 PM
Canadian_JOY Canadian_JOY is offline
 
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Location: Ontario, Canada
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Have had dual impulse mags on toggle switches and pushbutton start for years on my C85-powered "flying" airplane. Love this setup.

Pushbutton start is disabled by putting a lockout collar on the circuit breaker providing power to the start solenoid.

In our project aircraft, I went with the same setup, even though I have only one impulse mag on the left side of the O-360. The start button is under a flip-up cover which can be wired shut, in addition to the circuit breaker being collared (even a simple zip tie around the collar of the CB has proven a very effective way of ensuring the starter isn't accidentally engaged). The mag switches are mounted in "space shuttle" switch guards from Perihelion Designs. These guards facilitate the use of a long shank padlock or cable lock through them to prevent movement of the switch toggle levers. I don't think I'll ever need more security than this, but time will tell.
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  #13  
Old 02-16-2016, 06:47 PM
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JohnInReno JohnInReno is offline
 
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Location: Prescott Valley/Chandler AZ
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Default Marine key switch

Quote:
Originally Posted by KatieB View Post
I like the key idea just because of the extra security required to start the airplane, especially with a non-locking canopy.

For those who went with the push button start, do you miss having the security of the key?
I went with a marine key switch and 2 toggles. The switch is off-run-(start) and the "run" position powers the aprs transmitter.
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  #14  
Old 02-16-2016, 06:52 PM
BobTurner BobTurner is online now
 
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Quite honestly Katie I'd be worried about the liability if kids (teens) got in there and then had an accident. With no locks of any kind, the parents would claim it was an "attractive nuisance". I'd try hard to get some sort of canopy lock, even if it is no deterrent to a real thief.
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  #15  
Old 02-16-2016, 07:41 PM
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Toobuilder Toobuilder is offline
 
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Quote:
Originally Posted by KatieB View Post
...For those who went with the push button start, do you miss having the security of the key?
A push button starter does not preclude use of a conventional keyed ignition switch - both the RV and Rocket had both.

But I am with Mel. The keyed switch does not offer much security from theft and as far as switching devices go, they are far more complex and failure prone than other methods.

The only thing I miss about the key is the inability to remove the key and place it on the glareshield as verification that the ignition is off. Its a habit I've had since my early training and I still feel funny about leaving an airplane without completing that ritual.
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  #16  
Old 02-16-2016, 09:09 PM
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KatieB KatieB is offline
 
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Quote:
Originally Posted by BobTurner View Post
Quite honestly Katie I'd be worried about the liability if kids (teens) got in there and then had an accident. With no locks of any kind, the parents would claim it was an "attractive nuisance". I'd try hard to get some sort of canopy lock, even if it is no deterrent to a real thief.
That's pretty twisted. But yes, I agree in this age of stupidity and terrorism, a lock is a good idea.

On the other hand, if someone wants to steal my avionics, I'd rather have them unlatch the canopy/frame/skirt that took me hundreds of hours to hand-craft than break it to get around a lock and take my stuff anyway.

I'd probably favor wiring it so that the mags or starter can be disabled if I have to leave it on the ramp somewhere overnight. (or at an airshow)
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Last edited by KatieB : 02-16-2016 at 09:14 PM.
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  #17  
Old 02-17-2016, 06:05 AM
vic syracuse vic syracuse is offline
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The security provided by the key switches is really only for honest people. If someone wants the airplane or avionics I'd rather they not damage the aircraft. The key switches can be prone to failures, giving one a false sense of security that the mags are off, when in fact they can fail in such a way that they are not. Also, some engines like the Rotax, and some electronic ignitions, do not recommend the use of the keyed switches.
There are options to adding secruity to prevent an accident as has been mentioned above. I wire the START switch through the strobe circuit when possible. The strobes have to be on for the starter to work. Personally, I think it is a good safety practice to have them on prior to start anyway.

Vic
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  #18  
Old 02-17-2016, 06:33 AM
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Quote:
Originally Posted by Toobuilder View Post
The only thing I miss about the key is the inability to remove the key and place it on the glareshield as verification that the ignition is off. Its a habit I've had since my early training and I still feel funny about leaving an airplane without completing that ritual.
I feel the same way. It's a rule in my shop to not touch the prop until you personally have verified that the mags are off. That really is the only benefit of a key switch, IMHO. The key sitting on the glare shield means the mags are off.

It's certainly not going to keep a thief from stealing it, especially with impulse couplings, and especially with a carb. It is easy to cut the p-leads and hand prop the engine. At he same time, with a traditional key switch, the wires are labeled on the back, so cutting the p leads and arcing from bat to start is very easy, especially because most key switches are removable by hand anyway with pout needing any tools.

As for impulse couplings, some engines handle them better than ours, apparently. Some say the IO-540 doesn't like impulse couplings, which is why Van's engine comes without. We have a C152 with an O-235 with dual impulse couplings.

One strange thing I have seen recently is impulse couplings set at different timings to fire the coupling. One fired at TDC (which I am used to) and one fired about 15 degrees past. This was on Bendix mags and they were timed correctly.
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  #19  
Old 02-17-2016, 07:06 AM
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Weasel Weasel is offline
 
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Quote:
Originally Posted by Jesse View Post
One strange thing I have seen recently is impulse couplings set at different timings to fire the coupling. One fired at TDC (which I am used to) and one fired about 15 degrees past. This was on Bendix mags and they were timed correctly.
The difference in start timing you are seeing is called "Lag Angle". The manufactures use different "Lag Angles" for different applications.

The commonly used surplus Slick Mag that a lot of people retrofit onto VW aircraft conversion engines has a 15 deg "Lag Angle". The engine is normally times at 26~28 deg. This leaves you with the engine firing at ~11-13 deg BTDC and if the mixture it right and the prop not "slung" fast enough you get a nasty kick back.

Details

It is good to know the Lag Angle before you attempt to hand start any airplane.
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  #20  
Old 02-17-2016, 07:18 AM
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Mel Mel is offline
 
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Default Please be aware......

Just because the key is "OFF", the key is "out of the ignition switch", the key is "laying on the top of the panel", doesn't guaranty that the mags are grounded.

Unless you routinely check the "off" position, you can't be sure that the mags are off. The normal "run-up" mag check doesn't check the off position, and this is where most switch failures occur.

I personally have known of at least 2 failures that resulted in the engine firing with the key off, out of the switch, and laying on the top of the panel.
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EAA Flight Advisor/Tech Counselor, Friend of the RV-1
Recipient of Tony Bingelis Award and Wright Brothers Master Pilot Award
USAF Vet, High School E-LSA Project Mentor.
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