LeBurg ignition installation

[JimCrawford]

As the rework on GAVTC nears completion I've decided to fit the LeBurg ignition kit I've had stashed away for quite a while. The existing system is the classic 'Peacock' conversion and I will replace the Peacock magneto support plate with a similar one mounting the coils on it's forward face and the electronics boxes to the rear.
To get things moving along I propose to use two independent 7Ah batteries and recharge them off the aircraft, this will remove the delay of building the alternator system suggested in the LeBurg paperwork.
I know that several Nippers use the LeBurg system and the purpose of this post is to ask the forum how the alternator is arranged. Although the alternator fit described in the ignition papers is very slim it is still very slightly bigger than the distance available between the engine and the firewall.
Has anybody schemed a mod to the alternator mount which makes it even slimmer, or is the solution simply to pack the engine mounts forward by 5mm.? That's all it would take.

Here's looking forward to some good flying in 2016

Jim

[G-ARBG]

Hi Jim,

I'm not a great fan of electronics having suffered some problems with Leburg in the past which is why I retrofitted the chain driven mags to 'XLI, however my latest Nipper has the Leburg ignition system and so far there have been no problems. You do not mention which system you are using, internal or external? I have experience now of both and must say I prefer the external system for setting up and for access. I was also constrained by the use of the MK II Mounting which I retained for 'RBG. I have also now had my spare internal system removed from 'XLI modified by SkyCraft to the external configuration. I do like your approach to 'unitising' the installation by keeping the distributors mounted on the engine - good thinking, mine are firewall mounted using the existing firewall mounting bolts. for clearance behind the engine I had modified my firewall with a recess but your spacers sound like a simpler solution.
Photos attached relate to 'XLI , my earlier MK III Nipper now currently in store.

Regards,
G-ARBG

[JimCrawford]

Hi David,

Thanks for the info - very useful.

I was going to leave the chain driven mags on but thought the LeBurg more attractive and installation probably won't be any more effort than sorting out the mags, especially as I've already put all the wiring in place.
I'm trying to avoid mission creep so decided that if one of the mags had an impulse coupling then I would leave well alone. There isn't an impulse coupling so I'll go with the Leburg. The two batteries, no alternator system is to avoid the delay in building up the alternator mount, particularly as it will require some sort of rework to fit. I haven't sounded out the LAA with this but it is standard practise for me as a glider pilot to remove the battery pack at the end of the day and put it on the charger.
I reckon a 7Ah gel cell due for replacement at 75% capacity [5.25Ah] discharged to 50% [2.6Ahr] should provide 2.6/0.35 = 7.4hr of engine running with plenty of reserve for a day's flying.

The engine mounts may have to be remade if packing them forwards by 5mm leaves me with the securing nuts out of safety. But this can be done with the alternator prep in easy time while I'm flying the battery system.

I have the external sensors. I saw the internal ones on the diagram and thought that both sets are installed as normal, the Skycraft documents aren't comprehensive. Certainly I considered that the internal sensors could be problematic to set up. I have it from a Leburg user and personal observation that even the external sensors are not potted with a great degree of dimensional accuracy so getting the set up spot on can be a bit of a faff.

Many thanks

Jim

[jockthenipper]

Hello Jim and Dave,

Firstly, seasons greetings to all ! Well this was a timely post as I am now just on the threshold of starting to rebuild the engine for G-CORD and installing a Leburg ignition system. I now have 95% of the components, including the parts for the alternator mod sitting waiting in the workshop. However, one point that completely passed me by was the need to modify the firewall to accommodate the alternator mounting bracket? I had always assumed, because I have not even mocked it up yet, that the engine mountings were deeper than the associated components of the alternator? Obviously your post suggests otherwise! So, time for some measuring and perhaps, cutting, bending, drilling, riveting.....
Good luck with the LAA, I fear they may have reservations about your plan to operate the Leburg solely off battery power? The rules regarding gliders and motor gliders (single mag) are in general much more lenient than for aircraft that require a fan to keep the pilot cool. Single mag, single Leburg would work, but that makes my brain hurt.

The following is an extract from an LAA forum discussion on the subject of Leburg:

v) I think you will have to remove the engine because you will need to install an alternator (in my case, off a Honda motorbike) on the rear of the crankshaft to charge the two sealed lead-acid batteries that power the controllers. Unless they have changed their minds, LAA Engineering would not accept a Leburg installation without a way of charging the batteries. Also, Engineering would rather that the batteries are not in the cockpit with the pilot. In my case, I had no room in the engine compartment and I was allowed to mount them on the firewall above my rudder pedals (which are not the standard VP-1 design).

However, good luck, please keep us informed of your progress and I will endeavour to do the same. Now that the RV8 is flying I hope to devote much more time to the Nipper over the coming months!!

Peter

[JimCrawford]

Hello Peter,

Thanks for the reference to the LAA forum discussion, it was a useful read.

I think the only significant problem will be to persuade LAA engineering to allow the 'no generator' installation, and I hope I can do that with a reasoned argument on the safety case. Indeed my safety case may have been boosted by the accident report in the most recent mag (almost typed PF there!) where the engine failure was likely caused by the generator not being on-line. At least I will start with capacity verified batteries (incorporated into the 50hr check), fully charged using a proper 3 stage charger (no full charge indication - no fly), monitored by a meter on the panel and, finally, the LeBurg alarm signal complains when the battery voltage is low. The ignition systems are completely individually wired and fused at the battery terminals such that failures of the accessory loads such as the ICOM handheld and tablet moving map cannot take out the ignition system.
Sorting out power systems for scientific equipment on research aircraft used to be the day job and I'm afraid I'm not overimpressed by the LeBurg scheme, in particular the statement that the 2.6Ahr backup will power one ignition for 7 hours is rather iffy, probably more like 2 . See the previous post that calculates that a 7Ahr will just about do 7 hours.

Although the ignition requirements for motor gliders are regulated, these are in the main EASA aircraft, as are most gliders now. I don't believe there are any rules for permit aircraft and a reasoned safety case and operation scheme should be sufficient. Similarly the LAA may well rather that the batteries are not located in the cockpit area but pretty well every glider flies with non-spillable gel cells in the cockpit and has done without problems for many years.

note; Rules = must = mandatory, everything else is a recommendation = should = alternatives are acceptable.

If reason does not prevail and the LAA demand a generator, then I will engage plan B which is to fly with the Lucas mags until I can get the parts made up over the following year. And still fly with the batteries in the cockpit to power the tablet!

Jim

[jockthenipper]

Hi Jim,

It all sounds very logical to me, but, we are talking about the LAA!! I agree with your sentiment regarding precedence in other areas, but, having recently been through the process with my RV8 where I had to fit isolation switches for the trim and flap circuits because the LAA were reluctant to accept the safety features of the VPX power management system, it became apparent that the least course of resistance was going to save a lot of email ping-pong!! But, as I say, I wish you well and truly hope you are successful in persuading them. In fact I am sitting down tomorrow with my brother-in-law (ex RAF Radar Tech) to go through the electrical requirements for the Nipper. Very simple really, but I always like to have that reassurance! I hope Plan A works for you, let us know how you get on? While I am here you don't know of any Nipper Mk3 canopies lying around do you?

ATB, Peter

[JimCrawford]

Hi all,

I've had a bit of a merry dance with this Leburg installation so I thought I'd post an update to the forum. My intention is to write up the whole scheme for the LAA mag when it is finally an approved mod. I think that would be a good method of disseminating the information for use by anybody wanting to fit electronic ignition to a VW.

Inspection of the engine mounting studs revealed that I cannot just pack the engine out by 5mm to squeeze in the crankshaft mounted rotor between the engine and the firewall. The simple reason for this is that the studs are drilled for split pins and, although there is enough spare thread, packing the engine forward would move the split pin hole into the stressed portion of the thread within the nut. Not good! Making a new set of studs 5mm longer would make them identical to the ones drawn on the Peacock drawings of old but would be a right pain as the existing ones are perfectly serviceable.
The solution appeared when I printed out the firewall photo posted by GARBG on the second post of this thread. There is a trapezoidal recess in this firewall and it prompted me to revisit mine more closely. I had assumed that the fuselage structure prevented any such recess being useable but, as the picture below shows, the diagonal tubes do not pass directly behind the crankshaft. Indeed the photo reveals that there has been a previous hole cut in this position and a closing plate riveted on. The second photo shows that there is easily enough space to fit a can style recess to take the rotor.
So plan B is to reinstate the firewall recess and keep the original engine mounts. The geometry restrictions lead to a different mechanical support plate than that seen on the Skycraft/Leburg drawings and the result should be very neat.
Right now the Honda rotor is being fitted to a purpose made faceplate on my lathe so that I can spin it up and measure the electrical characteristics in order to design the regulator to correctly charge LiFePo batteries.

P1080658FirewallAft800x600.jpg (90.77 KiB) Viewed 19989 times

P1080660FirewallRotor800x600.jpg (92.46 KiB) Viewed 19990 times

Jim

[Neil Spooner]

Hi Jim,
I found the clearance to be very close on G-ONCS, but managed to get what I needed by adjusting the clearance on the Leburg assembly, reduce the length of the pillars, the back of the alternator rotor was then very tight to the rearmost plate. Do away with the nylok nuts supporting the stator windings, reduce the bolt length and use a quality thread locking compound. You will obviously have to check the clearance on the rotor mounting bolts to the stator.
If this does not get you what you need, then it is possible to use rolled thread studs and pack the bearers. This is what I did on the 2180cc conversion I did, only really because I wanted stronger studs. If you are interested in this let me know and I will see if I can find the invoice for the supplier. I can also send you drawings of the studs/spacers to your email address.
Regards,
Neil

[JimCrawford]

Hi Neil,

Thanks for your post and apologies for the tardy reply but I have been smitten by the Christmas lurgy which hits in the week before Christmas when I still haven't been out to get presents or to post any cards!

I am well into making the crankshaft adapters. I'm making a batch of three; one for the Nipper, one for my Taylor Monoplane and one for a 1600 engine I may get my sticky mitts on. Otherwise number 3 will be a spare in case I muck up one of the aircraft pair. I agree with your points about making the Leburg assembly shallower. My impression is that it was designed with hand work in mind whereas I have a small lathe and mill (Chinese but very usable) so I can cut items from the solid rather than fold sheet. This is particularly useful for the stator holder as it will have to fit in the circular recess. If, when I've built the alternator, it fits in without mucking about with the firewall I'll do so. Otherwise I'll reinstate the 'bean can' recess.

Pictures will be posted.

Your 2180 conversion sounds interesting. Is it a stroked early (MgAl) crankcase or the heavier type 4 (Al) base?

I shall now snuffle off into the sunset. At least being confined to barracks gives me plenty of time to relax - oh except for finishing the adapters
and designing the stator plate
and designing the backplate
and submitting the first part of the mod to the LAA
and laying up a new instrument panel for the glider
and fixing the insulation in the roof
and drawing up the remodelled en-suite for the builder
and preparing to be invaded by family next week (only an extra 10 this year)

Best wishes and seasonal greetings to All

Jim

[Neil Spooner]

Hi Jim,
You should not need to go to all that trouble. The only folded part is the back plate, why I am not sure, perhaps for support, but if you are going to run up a round back plate it won't have the support either.
Really, you should find the couple of mm you need by modifying in the manner I have suggested without having to recess the firewall.
The 2180 was a stroked magnesium case from Great Plains Supplies, not sure if they are still in business as Steve passed away this year. Force 1 hub for better crank support as I used to aerobat it quite vigorously! The crank is about 7lbs heavier than stock, but I used alloy cyl's which were 10lbs lighter.
Hope your lurgy gets better soon,
Regards,
Neil

[JimCrawford]

Hi, and a happy New Year to Nipper forumites

Can anybody tell me how they fitted the crankshaft O-ring seal in the Leburg crankshaft adapter?

I've got this part on the lathe and cannot reconcile various dimensions given on the drawing which is supplied with the Leburg kit from Skycraft. The quoted O-ring will not fit and the groove dimensions don't follow normal O-ring design practice.
I'd be very interested to know if anybody has made this part and how they did it. If a Honda CBR600 alternator is being used then this adapter must have been modified from the drawings.

Jim

[Neil Spooner]

As I recall the O ring dimensions are the same as the VW genuine flywheel O ring. I have stock of these hubs for sale to suit the CBR alternator if you wish to buy one.
FYI:

https://www.google.co.uk/search?q=vw+ty ... CN4QsAQIGg

Regards,
Neil

[JimCrawford]

Hi Neil,

Thanks for the information. I initially assumed that the Leburg drawings would just be a copy of the VW flywheel groove and O-ring but became confused when it came to cut the groove.
Two things still confuse me! The O-ring inside diameter is given as 56.5mm which cannot be correct as that makes it much larger than the diameter of the crankshaft. If you take that as a typo and say it's the outside diameter then, with a 2.62mm cross-section, the inside diameter becomes 51.26mm and I think that would be nearly impossible to assemble, the crankshaft would tend to push the ring out of the groove and into the flywheel. The second concern I have is that the groove is 2.62 wide, the same as the ring diameter which is not normal seal practice. Normally a 2.62 cross section ring would have a ~ 3.2mm groove to give a fill of about 75%. The narrow groove gives a fill of 90%

The best fit I can find is an ISO 3601 size of 53mm id and a cross-section of 2.5mm in a 3.2mm wide x 2.1mm deep groove. That size would match the normal seal design rules. No other standard size will.

I may just buy a VW O-ring to measure it to see what's going on. I don't know if I can get my hands on a flywheel to measure that.

Anyway Warco sent me the wrong size boring bar so I have to wait while that is sorted. I'll push on with the mounting plates.

Jim

[Lowflyer]

Hi Neil,

Do you still have any flywheel hubs for a leburg setup for sale.

Peter

[MalcD]

Hi Everyone, I’m new to the group and also to Nippers. Sorry if this a really old post but does anyone know where could buy a Leburg kit since Skycraft seem to have gone bust.
Best
Malcolm