Is there an alternative to mags or Leburg for homebuilts?

[rogcal]

With the Leburg system seemingly now out of reach and mags (in particular the Lucas SR4) not being everyone's cup of tea what alternatives are there for those utilising the ubiquitous VW as a power source.

One of the ideas buzzing around in my head is two distributors mounted where the mags are mounted, two coils and a battery!

OK, power supply to keep battery charged needs considering, as well as the weight issues but not insurmountable.

Advantages are:

Nice big fat spark
Major components and consumables straight off the shelves of the motor factors
Automatic advance/retard mechanism as standard
Contactless technology can be utilised.

Disadvantages:

Weight (possibly).
Distributor bearings not designed to take a side loading when driven off of belt or chain drive but neither are the bearings in the SR4 for that matter.
Need for battery/power supply.

I'm sure many others will have had these same thoughts at some time but why has no one progressed them beyond just thoughts? Fear of what the guys in LAA engineering will say! I doubt it, as innovation is something they promote and applaud when it works.

What got me thinking on the above lines is a modification I saw made to an SR4 installed on a marinised engine in a canal boat. Quite simply the mag had been turned into a distributor with the HT coming from an external coil with the HT lead being fixed the the HT pick-up in the cap.

So come on chaps, get your thinking caps on and let me know what you think and if I'm missing the obvious reason why this idea may not work, please tell me.

Incidentally, two SR4s weigh a little over 4kgs.

[Nigel Ramsay]

Roger, rather than taking what could be construed as a retrograde step (!), I would have thought it better to look into some of the aftermarket electronic ignitions designed for motorcycles. It ought to be possible to get one of the manufacturers to program a different advance curve to suit Aero-VW needs.

While the Leburg was no doubt a clever piece of design, in development terms, it's pretty old now and I suspect something even smaller could be developed today.

[Ian Melville]

I was chatting to Francis Donaldson a few months ago and mentioned the demise of the Leburg ignition system. His response that there were modern alternatives out there, but was not specific. Perhaps its worth giving him a call?

[rans6andrew]

An respectful time after the Sparrow accident I approached the Mickleburgh family with a view to taking on the Leburg name and continuing production. At the time the firm message was that Henry was going to carry on and would not want any outside assistance. I left it at that.

Now it would seem that the demand for modern ignition systems for the various VW (and similar) engine conversions is not being fulfilled. Perhaps I should look again at what I can do to help out. I suspect that the biggest hurdle will be getting a system "accepted" by the LAA. Have we an engine expert in the LAA engineering department who I should be talking to as a first step?

Rans6....

[cardiffrob]

Would it not be possible to remove the 2 SR4s and mount a pair of Lucas or Bosch distributors in their place? With the Leburg generator you'd be alright. Better starting, too.

[Nigel Ramsay]

Rob, it would of course, but my original point here was WHY would you bother? Magnetos are better than distributor/coil setups in terms of reliability. I gather you have a lot of experience with older vehicles, as do I. My 60 year old motorbike with a single magneto is a lot more reliable than say a Moggy Minor, which if you did any mileage at all needed constant re-eadjustment of points etc.

OK, there are now electronic distributors, I've fitted one to an MGB, all those problems have gone, but it's heavy in aircraft terms, ergo, why bother (my opinion of course).

If you are going to go to the trouble of changing things, then bung the chains/gears/magnetos etc for the much lighter electronic system of some sort.

I think the main problem, as I alluded to earlier, is that commercially there isn't the business for this, even if there were 100 people looking for this solution, it would at best be a garden shed operation. (I've been here before with a Rotax electric starter kit - 300 odd units sold before the E type gearbox stymied it forever).

I do believe however that those of us with an interest could pool our resources and ideas when hopefully we could come up with a system which could be available with LAA approval. What say you guys?

[rogcal]

Nigel, Foggy, Ian, Andrew et al.

Thanks for you thoughts and suggestions and yes I agree that with enough heads around the table we could come up with something that would suit most people and more importantly our good friends at LAA engineering.

For me, automotive and off the shelf has got to be the way forward. Wasn't that why the SR4 found its way into the aviation world in the first place!

Lightweight coils do exist and are readily available, as are lightweight alternators but beyond that everything else is standard automotive weight and as such there will be a weight penalty but of how much I can't say at the moment (I plan to visit a few motor factors with the kitchen scales,so watch this space).

As for electronic components (apart from replacing the points in the distributor), these are generally designed for specialist use in racing bikes and cars and are invariably set up for specific performance needs and are most definitely not cheap, nor appropriate for our needs as an off the shelf component.

Yes, it would be great if the Leburg system was still available or someone else came up with a similar design but with all "garden shed" companies, the likelihood of the supply drying up for many reasons, as we've seen with Henry M of late, is something we'd either have to accept or look for an alternative set-up that doesn't see us relying on one or two individuals/producers.

So, where do we go from here? We either agree that the (light weight) automotive parts route is the way forward or do we faff around endlessly looking for alternatives much in the manner I'm all sure we have already been doing for years.

May I suggest we continue this dialogue via email but still invite anyone else who may have any ideas to post on here and in the meantime a core group can work on what ideas ideas we already have and take them forward collectively rather than individually.

[Bill McCarthy]

As the majority of LAA members don't visit this site, perhaps an article in the magazine could arouse more interest in this subject - after all, there are an awful lot of VWs out there (and will continue thus, considering the terrible costs of new Rotax etc) reliably pulling aircraft into the sky. I'm sure there are a few mechanical and electronic experts out there who could solve this for us.

[G-AWMN]

Roger,

I have been thinking about this for a while. My current project is getting close to being finished and I am looking into a follow on project. My biggest issue with a new project is the engine. Can you keep me in the email loop. (You already have my email address)

What I want is an inline air cooled, port fuel injected, about 75hp modern equivilant of a Walter Mikron (Guess the project?)

I work as a CAD designer for Ford currently working on petrol engines (or gas as Ford is an American company). Unfortunatly a lot of what we are working on would not be suitable for aero use. For example we are generaly reducing capacity to help improve emissions, reducing cylinders to reduce friction and getting performance back by turbo charging. But working with these technology gives me a lot of ideas and the good thing is when I am at my desk doodling a possible aero engine nobody notices!

Have you had a look at the following links. I work with a guy (day job, cylinder head engineer) who is using a Megasquirt system in a kit car and he is quite impressed.

http://www.sdsefi.com/

http://www.megasquirt.info/

Stuart Penfold

[Rob Swain]

Would it not be possible to remove the 2 SR4s and mount a pair of Lucas or Bosch distributors in their place? With the Leburg generator you'd be alright. Better starting, too.

I think you've used the drive off the 'back' of the VW twice with this suggestion.

Not impossible, but the thrust bearing that holds the mag/distro drive AND the alternator rotor is going to be a bit big. I think a lot of VW powered aircraft (e.g. VP1) might have trouble accommodating this.
Also, I suspect that changing belts for the mags/distros would be an engine off job with such a solution.
You'd be better making a pulley on the thrust bearing and driving a small car style alternator under the engine alongside the distributors. Sounds feasible, but as has already been said, heavy.

The Great Plains VW conversion uses new Slick mags driven 'directly' off the back of the engine. Of course this then becomes expensive, and you still have the issue with the firewall clearance.

The suggestion of reprogramming a motorbike system to suit a VW sounds like a good idea but I think is a non starter. No manufacturer would bother for the volume - or rather lack of volume - involved in the aero VW market. Dave M produced Leburg ignitions as a labour of love / charity as far as I can see, having bought a system from him. I hope he didn't make a loss on the systems he sold but I can't believe there was much more than beer money sized profit in it.

We should corner Francis Donaldson and get him to explain his 'other alternatives'.

[Brian Hope]

There are already a number of ready made options. Great Plains makes a single mag mounting that fits to the rear of the engine to take a Slick mag (the flywheel end), and also electronic systems that drive from the normal distributor position and off the oil pump. It would also be a relatively straightforward job to make up a low level hall effect or optical distributor and trigger a proprietory electronic module.
The mag option is only useful if you have room behind the engine, as unlike the variations of the Peacock theme, the mag extends from the end of the crankshaft rather than fits beneath the engine facing forward. That said, a Slick mounted under the engine as a single unit driven by a belt drive off the crank would not be beyond the wit of man. You could then use a single electronic system as a back up and not be totally reliant on battery. Some installations of course, only require single ignition.
Then again you could use a Peacock style system but suplement P-Mags instaed of conventional magnetos, not a cheap option admittedly.

[Nigel Ramsay]

Whilst I have a complete and as yet unused Leburg kit, this thread has sharpened my interest! I'm going to have a conversation with a couple of motorcycle electronic ignition guys when I'll ask them if they could/would adapt their kit to the same timing curves as the Leburg (in the absence of better info).

I will report back!

[Will Greenwood]

Now I know that Roy-Watling Greenwood, fitted his own adaption to a mag on his Turbulent that is at Deanland, it uses a simple battery to produce a simple better starting solution for VW engines, I guess the PFA/LAA as it is now may have the origional mod, might be worth digging out ? Turb is G-AWDO, so ask the engineering section of the LAA NOT THE OWNER !!

[rogcal]

Will, I think you may be referring to a device I believe was originated by Tony Oliver as a mod to the SR4s on his Fred (G-OLVR).

I have a diagram of the set-up somewhere that he gave me some 20 odd years ago and consists of a 3v dry cell battery wired via a switch into the primary coil of one mag and is designed to boost the output of the secondary coil for starting only.

Never tried it myself but the principle is sound and I'm sure it would help a tired mag with little output when being hand started!

I wouldn't hold out to much hope on the prospect of the details being easily accessible through LAA engineering, as many mods have not been recorded separately if they were part of an original engine conversion.

If anyone wants a copy of the drawing I have please PM me and I shall endeavour to scan and email it to anyone interested in it but please bear in mind that any use of it as a mod to an SR4 attached to a VW engine installed in an LAA permit aircraft would require a minor mod authorisation.

[Nigel Ramsay]

This mod WAS written up in an old issue of the PFA Magazine some years ago. I remember reading it.