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 Post subject: G-CORD Rebuild
PostPosted: Sat Jan 19, 2013 8:58 pm 
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Joined: Sun Oct 14, 2012 2:34 pm
Posts: 48
Hello to All,

I have recently purchased G-CORD, (a Slingsby built Mk3), which was damaged in an accident about 18 months ago, with the intention of returning her to her former glory! I have no particular timescale in mind for the rebuild so, at present ,I am trawling the forum site to get a feel for the mods that are available and could be incorporated during the rebuild.

As Nipper owners and flyers, can I ask you, if you were in a similar position what would you look to incorporate during the rebuild process?

I will be using the original VW Ardem X engine, 1834cc and my thoughts so far include:

Leburg Ignition
Auxiliary Fuel Tank
Up graded Brakes
New Canopy? (Original damaged in accident)
Inverted oil and fuel

Any advice or guidance would be welcome and I look forward to contributing to and eventually swelling the Nipper fleet!

Many thanks.

Peter Gilmour
G-CORD


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Sun Jan 20, 2013 9:02 pm 
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Joined: Tue Oct 10, 2006 7:29 pm
Posts: 122
Location: Salisbury
Greetings Peter,
definitely the best mod I did (G ASXI) was bicycle hydraulic brakes. The were a fiddle to set up
but once sorted are great. They will hold me at full throttle on tarmac.
Others I would recommend are the bungee mod
, some sort of adjustable trim tab, Jabiru engine (electric start!!!)
Tall pilot mod (involves relocating the seat back cross tube and rudder pedals mod.
The others you suggest are excellent mods with varying degrees of difficulty, the inverted
oil and fuel are tricky and expensive (ask yourself do you wish to fly sustained and inverted...
for my money semi aerobatic is fun enough)
Any way I wish you well with the project.
Keep us all posted on the progress.
All the best
Pat Very Happy


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Fri Jan 25, 2013 7:24 am 
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Joined: Tue Oct 10, 2006 6:14 pm
Posts: 192
Location: INVERNESS, SCOTLAND
For me it is the Leburg mod, if you can get a kit. No more kickbacks when handswinging, smooth running, benefit of a generator fitted, and reliable first swing starting once you learn how she likes to be primed.
Generally fit and forget.. whats not to like?
Tip tanks are very useful, other supplementary tanks could also be made.
I don't have inverted and don't feel the need.
The only remaining mod for me is to replace the u/c rings with bungees then i will leave well alone.
Hoping 2013 will be a more active year for G-NIPR, although a few work glitches to get over first....
Best wishes all,

Paul
G-NIPR.


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Sat Jan 26, 2013 8:48 am 
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Joined: Sun Oct 14, 2012 2:34 pm
Posts: 48
Hi Guys,

Many thanks for your thoughts and guidance to date. As with all rebuilds I realise that compromises will have to be made, just want to make sure I choose the right ones!!

The fuselage is currently still under repair with Paul Grellier, so I will discuss the incorporation of the mods you suggest as they all sound very practical it would be sensible to do them at this stage. Pat, could you tell me what make of bicycle brakes you used? Given past experience with mods and the LAA I am not too proud to walk a well trodden path, so I hope this does not cause offence to anyone in the Group!!

Paul, thank you for your thoughts also, the Leburg is a definite, having restored a VP1 to flying condition last year I am now reasonably versed in the ritual and mantra of VW starting! Anything to avoid that is well worth it. Fortunately Skycraft are now producing brand new 'Leburg' kits.

I live a vagrant life commuting between St. Andrews and Exeter, so if anyone is intending to fly into Dundee, Leuchars, Kingsmuir, Glenrothes, or Dunkeswell, Branscombe, Farway Common or Watchford Farm respectively this year then let me know.

In case you are wondering why Neil has not appeared on this thread, I have had a lengthy exchange with him offline. As ever he was extremely generous with his time and knowledge, I am hoping I have not exhausted his patience just yet!


All the best, Peter


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Sat Jan 26, 2013 11:58 am 
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Joined: Tue Oct 10, 2006 7:29 pm
Posts: 122
Location: Salisbury
Greetings Peter
The brakes I used are Magura, a popular and robust example which are mid price.
Frankly any of the popular makes will do as the mounting holes are an industry standard.
You will have to make up some brackets and spacers and be careful that the calipers dont
rub on the tires. On mine the tolerance is quite close and much fetteling was required
but the result was worth it.
I will endevour to get some photos next time I go to the hangar .
All the best with the project. even though I am selling up I maintain a keen interest
in all the nippers out there. Let me know next time you are at Paul Grellier's as I
keep ASXI at his strip and used to work for him untill recently.
Regards,
Pat


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Sun Jan 27, 2013 10:05 am 
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Joined: Sun Oct 14, 2012 2:34 pm
Posts: 48
Hello Pat,

Thanks for that, I will take a look at their website. The fuselage is currently being repaired so it just makes it that much easier to incorporate these mods, such as mounting brackets, now. A couple of photos would be very welcome when you have a chance.

I am sorry to hear that you are leaving the Nipper fraternity as it certainly has a feeling of enthusiasm and mutual support about it. I will certainly let you know the next time I am heading for Paul's. No real deadlines, but probably looking to come across and pick up the fuselage sometime in March.

Thanks again for the advice. Peter


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Fri Feb 01, 2013 9:47 am 
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Joined: Wed Oct 11, 2006 6:55 am
Posts: 485
Location: Ardleigh, Colchester, Essex, UK
Hi Peter,
Just to "close the loop" (pardon the pun!)
Seat mod': The a/c has to be comfortable to fly and being too close to the controls limits their movement, not good.
Fin mod': Fitted with the fin mod' the a/c will fly much more accurately, knife edge beautifully, 4 point roll, slow roll, all without worrying about those little rudder hinge pins failing (the loading is enormous being so close together) The a/c will also maintain a heading very well if you enter imc.
Leberg for all the reasons already stated.
Inverted fuel and oil: Fitted with a carb' the engine will stop if any unintentional neg' G is encountered, without a starter the outcome can spoil your whole day! (I know!) I cannot imagine owning an a/c without neg' G capability now, the aerobatic maneouvers open up dramiticaly. 4 or 8 point rolls, stall turns, rolling circles, proper round loops, etc etc.
Bungees for long term serviceability.
Second hoop inside the front turtledeck hoop with a second diagonal brace bar for roll-over protection.
Aux' fuel tank mounted under the main: None of those ugly tip tanks that don't feed and can lead to engine stoppage if not managed correctly (I am bracing myself for the "pro' tip tank brigade"!!)
Trim tab on the elevator: Very precise, and should you loose the elevator control (can't see why you could) you can fly the a/c on the 'tab.
Hydraulic brakes....yet to fit mine. The originals won't hold the a/c with any real power applied. I use chocks to run up on (with me strapped in the a/c) and once all checks done use full power to jump the chocks, it also gives me an opportunity to check full RPM before I commit to the sky.
A BIG engine! Fitted with a 2180cc in good fettle and an exhaust that allows the engine to breath I can complete a full vertical roll before I run out of puff.
I think that's it. EDIT: Not forgetting the extended rudder pedals for longer legs of course!
Neil

_________________
A little help goes a long way.
G-ONCS


Last edited by Neil Spooner on Sun Feb 03, 2013 8:24 am, edited 1 time in total

 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Sat Feb 02, 2013 8:59 pm 
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Joined: Sun Oct 14, 2012 2:34 pm
Posts: 48
Hello Neil et al,

My thanks to you and the other members, I have now made contact with Dave Shrimpton who has kindly offered to let me view his fleet! It is great to have this level of support while I am still feeling my way.

The engine is now completely stripped and I spent yesterday splashing around in petrol and degreaser cleaning the cases. As I have other building and financial commitments with my brother-in-law with the RV8 I have (almost!) decided on the following plan of action for the Nipper in the short term:

New crank. (Is it worth paying the extra for the forged 4140 or 4340 steel version?)
New pistons and cylinders (Planning on forged rather than cast?)
Head decoked and valves lapped
Leburg ignition
Oil cooler
Throttle Body Injector (Any advice on make or model appreciated?)
Internal Auxiliary fuel tank (Neil do you still have any specs for that mod?)
Hydraulic brakes
New bungees
New propeller (original damaged in accident, again any recommendations from the Group?)
The fin mod is already under way with Paul
Tall pilot mod likewise will be incorporated at this stage
Noted the idea of a second hoop for roll protection and sounds very sensible

The fully inverted fuel and oil system will probably have to wait for the moment, but if there is something I should be doing to future proof this intention then please let me know.

The other major item is to load test the wing, not because I believe it was damaged in the accident,but, I would rather hear a crack standing in the garage floor than at 3000'!! Can anyone point me at a website that provides a description of how to obtain the loading required, or am I being too scientific?

Thanks to all for indulging my ignorance once more.

Peter


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Sun Feb 03, 2013 8:56 am 
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Joined: Wed Oct 11, 2006 6:55 am
Posts: 485
Location: Ardleigh, Colchester, Essex, UK
Hi Peter,

Regarding the crank: The improved cranks are well worth the effort, but I would incorporate the inverted oil feed mod' to the engine (I can do that for you) and fit a stroked crank. You now have a problem in that a longer stroke needs the inside of the c'case to be machined so the rods clear the case. John Maher can do that. You now have another problem in that all the stroked cranks that I know of are counter-weighted, this adds 7lbs to the crank weight which you need to offset with alloy cyl's. Like the proverbial hens teeth they are rare (I have a spare set, but you can't have them!) Contact Revmaster, the last time I talked with the CEO Joe he still had some. And while you are at it go the whole hog and fit a crank with the full fwd bearing (Like the GPAS "force 1). If you are going to really enjoy aerobating your Nipper like I do the gyroscopic loads on a std crank nose may leave you propellor-less one day. Now you have built a bottom end that will provide you with more torque/power and will last.
Cyl' heads need to be very carefully worked. Clean out all the "flashing" from between the fins and increase the air gaps as much as you can. I use a drill and an angle grinder to get between the fins, you need to allow the heads to cool. Make sure you cut the valve seats with 3 angles to get the best performance from them, and ensure the seats are the correct width. Fit stainless quality valves to allow unleaded use, and set the combustion chamber volumes at 8:1. (make sure they are all balanced)
The 'heads I use are from GPAS, big valves with the 12mm top plugs, and 10mm bottom plugs. This dramatically reduces the chances of 'heads cracking.
The inlet and ex' gas flowing on std heads is appalling, they should really be reworked.
The inverted oil feed mod' can be used with a non inverted system.
Forged pistons are best.
Oil cooler is a must. If you go with the "force 1" crank or derivitive you now have room to fit the Revmaster oil pump and oil filter setup. Very light and an excellent insurance policy.
I use an EFS2 Ellison Throttle Body Injector (TBI), these are no longer available (I have a spare but you can't have that either!) I was having problems with it, and splashed out on a brand new Rotec TBI, this I have not used and is for sale if you are interested. The TBI is the perfect carb' I think.
I have a jig to bolt down the wing to the workshop floor and the Shrenk wing loading for you if you want it. I borrowed bags of sand from the local garden center, weighed each one (there was a slight weight discrepancy between each one), loaded the wing to +4g and measured the flex of each wing as it was loaded. This will tell you if there is any difference between the wings and any weakness.
The prop' I am using is an Ed Sterba unit. With the extra power and torque I am pulling another 6 inches of pitch. My cruise speed is 97kts at 3100rpm.
Throw away the cowlings! I have Barry Smiths cowling mold here, also my own derivative of it as the Force 1 prop' hub places the prop' about 1.5" further fwd. The BS cowlings are worth about 7kts on their own I reckon and look lovely.
Make sure you have engine baffles and baffle seals that work very well with no leaks. The VW engine is very reliable, its the installation of it that usually makes it unreliable.
Fit an engine vacuum gauge, it will tell you much more about the health of the engine, and will also tell you if the engine is set up correctly during development.
......my fingers are getting tired now!
Neil

_________________
A little help goes a long way.
G-ONCS


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Mon Feb 04, 2013 8:47 pm 
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Joined: Sun Oct 14, 2012 2:34 pm
Posts: 48
Hi Neil,

I am not surprised your fingers are tired! Many thanks again for the info. Spoke with John Maher today and it appears that L&N Engineering still produce 'Nickies' but they come at a price...... $2500! Which is beyond the budget at the moment. I have also emailed Revmaster to follow up that lead as GPAS only advertise the 94mm version at present and although cheaper than L&N they are showing as out of stock at the moment. I also spoke with John regarding the inverted oil mod, am I correct in assuming that this mod is sometimes known as the 'Hoover' mod?

I will PM you regarding the wing jig, Shrenk data and the Revflow TBI. The offer of the cowling moulds is also very gratefully received as the originals were damaged in the accident. The only other hen's tooth I have to track down is a new canopy, although I know Paul at Airweld is also looking at a potential supplier.

All the best, Peter


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Tue Feb 05, 2013 8:50 am 
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Joined: Wed Oct 11, 2006 6:55 am
Posts: 485
Location: Ardleigh, Colchester, Essex, UK
Hi Peter,

I have just sent my roster to you, pls let me know when is good to come down.

Joe at Revmaster has emailed me back:

We have not yet pursued the alloy 92mm cylinder. In order to make it from an alloy material, you would h ave to reduce the bore diameter to get the proper wall thickness to withstand the combustion pressures. The same goes for the 94's. We only have the lightweight version of the 94 cast iron cylinder. Total weight reduction is prox 3 lbs/set of 4.

Joe Horvath


The inverted oil feed mod' is not the Hoover mod', although you would be wise to incorperate those when you build your engine. You will need a very long drill for the cam oil feed one.

I may have found a new Nipper Mk2 canopy unused, but I re-iterate, for the seat recline mod' I would also mod' the turtle deck to the Mk3 config'. I am however in correspondance with an outfit that may be able to make the canopies, and know where there is a mould.

Neil

_________________
A little help goes a long way.
G-ONCS


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Tue Feb 05, 2013 6:39 pm 
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Joined: Sun Oct 14, 2012 2:34 pm
Posts: 48
Hi Neil,

Thanks for that, have PM'd you with a possible date to visit.

I also emailed Joe at Revmaster regarding the Nickies, but it looks as if the 2300cc engine is the only option at the moment. Can you provide me with more detail regarding the turtle deck mod as I spoke with Paul Grellier today and he is not familiar?

Good news about the canopy, looking forward to discussing with you when we meet up.

All the best, Peter


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Sun Feb 10, 2013 7:01 pm 
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Joined: Sun Nov 08, 2009 5:31 pm
Posts: 30
Hi Peter,

My Nipper is a Slingsby Mk3 and I've been attending to a few mods, although glider winter maintenance has kept me busy since last October.

I have posted some progress on the engineering forum, topic:
GATVC; seat & harness, wheels & brakes, & instrument panel
I would recommend the full depth seat for comfort - with the tall pilot mod, mine has an upstand around the edge to act as roll-over protection, and also, if yours has the shoulder straps attached to the lower longerons, use the mod that moves then to the upper longerons. There are some photos on the engineering thread that explain in detail.

I have fitted bicycle discs to replace the originals, and these could be used with the original calipers and probably would not constitute a mod. However my calipers are shot so I'm fitting a bicycle set which will be considered a mod. If you have the 4.95 x 3.5 tyre then fitting an alternative caliper is quite tricky as there is very little clearance available. If you have the 400 x 4 size then there is significantly more room. I would expect that hydraulic bike brakes would require the 400 x 4. I've had to use cable calipers for my 4.95 x 3.5

I'll go for the suspension bungees when my u/c suspension needs refreshing and I am considering a Leburg ignition as an RF4 here at Bicester has had a system fitted to good effect. However these parts are serviceable at the moment so, as they aren't broke, I'll not fix them.

Jim


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Wed Feb 13, 2013 6:48 pm 
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Joined: Sun Oct 14, 2012 2:34 pm
Posts: 48
Hello Jim,

Good to hear from you. Thanks for the pointer, I am away on a family holiday at the moment, hence my delayed response.

I will certainly take a look at your thread and come back to you with any questions. I am hoping to visit Neil in the not too distant future to pick his brains and probably call in at Airweld on my way back to check on progress with the fuselage rebuild. I will also check the tyre size when I am there.

As I have mentioned before, just trying to avoid any pitfalls and set in motion all the mods I need with the LAA so I do not end up waiting for the paperwork!

Thanks again for the advice. Peter


 
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 Post subject: Re: G-CORD Rebuild
PostPosted: Sun Jun 16, 2013 7:35 pm 
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Joined: Sun Oct 14, 2012 2:34 pm
Posts: 48
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Hello All,

Just a quick update on the progress with G-CORD. Finally managed to conduct the load test on the wing thanks to Neil for the loan of the stand and for the support from others here in Dunkeswell who assisted. The test was set up completed and dismantled again within the day which was a great relief to me as it was set up in a working hangar. Luckily everyone was away flying that day!

The fuselage is now ready for collection at Airweld so I am hoping to get across there in the next few weeks to bring her back to Dunkeswell. Next job is recovering the wing while preparing and collecting parts for the engine rebuild.

Will post another update as soon as the wing is recovered.


 
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