Magneto design. 1

[RoarkS]

Who's got the drop on magneto design info.

After watching Elliot Seguin's trials with the down lock failure causing his hydraulic pump cycle against a wall taking out his main bus, dropping the ECU and Fuel pumps... I feel a renewed desire to figure out a 5 cylinder magneto design. Something I can make with a laser (sheetmetal/laminations) and a CNC (billet parts). I'm thinking I can steal any coil from a slick or bendix, but not 100% on the electrical design stuff.

I'm sure someone has a WWII book that details the design pretty good.

 

[Sparweb]

Not sure how the two stories are related. On the one hand, here's an experimental kit-builder who might not know enough about system design to test his flight critical systems before getting into flight. I speculate that performance anxiety rushed him once he got himself on Red Bull TV. Seguin gets the hype of putting jets on his homebuilt, but forgets/ignores the track record of Jim Bede.

On the other hand you're asking about magnetos which are a quintessential piston-engine accessory.
Any way you get your inspiration... the first thing that comes to mind for you is Bingelis; Firewall Forward.

 

[3DDave]

Not sure how a magneto could figure into it - they supply spark to the plugs.

https://www.aopa.org/news-and-media...flight-training-magazine/how-it-works-magneto

Seems like the p51-miniature was a victim of poor system design and verification at several levels. How hard is it to put an ammeter into a circuit to verify the total electrical draw? Or just add up the ratings on the datasheets?

 

[RoarkS]

My point of bringing it up: With a small team, limited resources it's easy to do something stupid without realizing it... until thankfully he was watching the plane get foamed.

I was planning on using an automotive ECU that has never even heard of DAL. Probably a bad idea with me and only 2 other engineers to bounce ideas off of.

Magnetos... pretty simple. safer.

I'll check out Bingelis Thanks!

 

[verymadmac]

My first response is what does Verner Motor use on their 5 cylinder engines. I have seen mention of someone (non cert aviation) flogging electronic ignition suitable for 5 cylinders (thought it was SDS but can't see it on their website).

There is a little bit here

https://www.enginehistory.org/Accessories/Magnetos/Magnetos.shtml

Edit
Found another good link

http://aeroelectric.matronics.com/Mfgr_Data/Magnetos/Continental_Motors/IGN-51_Magneto_TM.pdf

 

[RoarkS]

verymadmac

That chart right there says a lot.

I'm going to the same type of 4 and 6 mag tonight... pretty sure they use the same rotating magnet,coil,cap... if that's the case that table shows that 5 cylinders are still just using 2 poles, then the rest should just be some gear box mods.

Someone had told me a year or so about that the speed of the rotating magnet could really mess with the frequency or something. I have no idea if they knew more or less than I do.

 

[verymadmac]

a bit of mike busch failure analysis of mags here

https://resources.savvyaviation.com...icles_eaa/EAA_2013-05_the-redundancy-trap.pdf

From this I wonder if there is market for a little bit of electronics that detects random mag firing and indicates mag failure to the pilot.

 

[kontiki99]

I understood some of the latter WW2 high altitude fighters went to a magneto design with the coil at the spark plug because the lower air pressure enabled more ignition lead arcing. I would be curious to see where to find specs for WW2 era equipment.

My posts reflect my personal views and are not in any way endorsed or approved by any organization I'm professionally affiliated with.

 

[WKTaylor]

Fairbanks Morse Magneto Fundamentals of Design and Service...

https://www.ebay.com/itm/291694708797

The Magneto Ignition System - as used on Continental and Lycoming Engines...

https://www.amazon.com/Magneto-Ignition-System-John-Schwaner/dp/B0006P6ZLW

Magneto encyclopedia - Magnetos 220 Service Manual

https://www.jensales.com/products/magnetos-220-magneto-service-manual.html

... This is a 968 page factory written reproduction service manual and would have been given to the dealer service shops back when your equipment was new.

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[jotunn]

On the one hand, here's an experimental kit-builder who might not know enough about system design to test his flight critical systems before getting into flight. I speculate that performance anxiety rushed him once he got himself on Red Bull TV. Seguin gets the hype of putting jets on his homebuilt, but forgets/ignores the track record of Jim Bede.

1. That's an unfair characterization of Elliot.
2. The TWERP program (Quickie with turbines) isn't the test program RoarkS is referring to. Suggest you look at the Titan Mustang program...perhaps it'll help you with context (and maybe even change your opinion about Elliot's abilities).