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Author Topic: Gasparin charger - help please!  (Read 861 times)
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Martha
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« on: January 30, 2017, 06:09:20 AM »

Hi all!  I am new to this forum, so please excuse me if I start with a little introduction.  I have been aero-modelling for around 50 years, having followed the well trodden path starting with gliders and rubber powered models before moving through CL and eventually to RC.  Throughout, I have preferred 'real' aero-modelling and have retained my interest in all branches of the hobby.  In recent years I have found that I am enjoying the 'real' aero-modelling far more than my RC gliders and I have thoroughly enjoyed building and flying a number of CL models.

During the '90s I dabbled with CO2 models, though with only limited success.  I predominantly used a Modela but was also given a well-used Telco and Humbrol Mach 2 at about this time, along with their chargers.  I recently dug out my old Modela and I have built a modified (lightened!) Little Deer for it to power.  Once the temperature rises and the weather improves I shall see if I have improved since the last attempt!

Whilst building the Little Deer I have read and learnt a great deal more about CO2 models, such that the 'bug' has bitten for building smaller and lighter.  To that end, I have ordered a couple of Gasparins (43 and 160) from Flitehook, along with an adaptor for an Alcojet bottle, however I realise I will have to wait for the adapter as it will be dependent upon Derek Knight being able to make one for me. In the meantime, whilst I await my Fltehook order, I have acquired a Gasparin 63 from ebay and I am building a Tomtit for it to power.  I hope to get it ready before the end of the indoor season at Shepton Mallett.  With luck, if the motors arrive from Flitehook, I have a Guillows F58 fighter waiting in the wings that may also be ready in time.

Whilst I wait for the Alcojet adapter I am able to use sparklet bulbs to charge the Modela, however I have no means of charging the Gasparins - hence my request for help.  The fill nozzle for the Gasparin tank is a smaller diameter than that of my other chargers.  Does anyone have a charger that I could use with the Gasparins that they would be willing to let me purchase?  Alternatively, does anyone know of a source for a suitable charger? I have the Alcojet bottle, I have the sparklet bulbs, I just need a means of getting CO2 to the flight tank!

Thanks in anticipation!

 
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union model
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« Reply #1 on: January 31, 2017, 01:51:19 PM »

I'd just sit tight and wait for a Soda Stream charger from Derek Knight, it will solve all your problems.

You only had three charges from a sparklet bulb, the second charge being the best. From my experience, the sparklet charger is a waste of time.

Mike.
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Martha
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« Reply #2 on: February 01, 2017, 03:24:35 AM »

In the spirit of experimentation, last night I set to and measured the tank filler nozzle on each of the motors that I now have (still waiting for the order for two new Gasparins from FliteHook).  Given that they are a mixture of plastic (two Modelas and the Telco) and metallic (G63 and Humbrol Mach2) I just used vernier callipers.  The results were interesting... all of the nozzles fell within the range 1.8 to 1.9mm od.  So on the basis of nothing ventured, I tried a sparklet charge using the youngest of the Modela chargers, which also looked to have the best rubbers (the Telco and Humbrol chargers, like the engines themselves, have definitely seen hard use before I was given them). Surprisingly, the Modela charger worked perfectly with them all.  The downside being that I now have found that the tanks leak on the ebay purchased Modela and G63 and that the capilliary feed to the head on the Telco also leaks.  Biggest surprise of the evening was that the Mach2 seemed to work fine!  As Union Model points out, the sparklets are only a stopgap at best, so I will just have to be patient and await Derek making an adapter for my Alcojet bottle.  In the meantime I remember there being a discussion on here about fixing leaks which I need to find!
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union model
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« Reply #3 on: February 01, 2017, 03:14:42 PM »

Are your co2 engines leaking at the soldered pipe work joint?  Or is it leaking below as there's an O ring which could be perished.

Charge the engine and dipping the filler,  tank and pipework up to the cylinder head (Make sure no water enters the exhaust ports) in cold water, is a good way of finding exactly where the leaks are.

If the leaks are in the soldered joint, remove the O rings. Insert some fine stainless steel wire In  the copper tubing pipework, stops the residing solder blocking the pipes and resolder the joint.

If any of the O ring are hard, replace it with a new one.
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DHnut
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« Reply #4 on: February 01, 2017, 04:09:11 PM »

A further tip is to lightly smear the O rings with oil as this seems to give a better seal. I concurr with changing O rings if they have gone very hard as they will not seal well.
Ricky 
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Martha
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« Reply #5 on: February 02, 2017, 03:48:46 AM »

Thanks for the advice; I had wondered if immersing the problem area would be the best way of tracking the leaks, but it was too late to make a start at the time. I tend to look and ponder an issue for a while before getting stuck in the first time, so your confirmation of that approach is welcome.  I had thought about using the 'spit' test on the pipework to the head of the Telco as an alternative so as to avoid having to risk getting water into the motor?
I spent yesterday evening taking a closer look at the problem areas and did a bit more web searching to try and see what they were meant to be like originally. 

The ebay G63 leaks from around the tank to pipework joint.  The area appears to be lightly epoxy-potted with a translucent white smear of epoxy. It looks to be the part of the original manufacturing and I found a comment from an article on the Gasparin site that implied that earlier tank joints were constructed in this way.  Whatever, I guess I will have to heat-soften the old epoxy, pick it away from the affected area and redo the joint, assuming that it wasn't originally cured at a high temperature. Given that the tank looks to be Al, it cannot have been cured much over 50 -70degC I would guess?

The Modela leaks around a swage line at the top of the tank, so that may be a case of mechanical and chemical cleaning, epoxying and then carefully heat curing.

The old Telco has been very obviously re-soldered around the head to pipework joint in the past, though the pipework may also have been kinked at some point at the joint, so I will need to test it carefully before I rush into taking it apart.  Fortunately amongst the odds and sods that I was given at the time were a couple of original Telco sealed packs, one containing O-rings, hand-labelled '3823'. The other is labelled 'ITl03' (this latter is very badly written - I am guessing at a couple of the letters/numbers) in the 'part no.' box on the packet, but it is obviously a replacement filler valve for the tank fill pipe. With a bit of luck one of the O-rings may be for the head!

Union Model, you suggest using a piece of fine SS wire to stop solder ingress to the pipe - another issue that I had been pondering.  Have you any suggestions for a source?  It is clearly very fine and I am struggling to think of anything that I may have lying around or which could be found at work.  I have some access to a/c maintenance and instrumentation build facilities/equipment which may yield something suitable.

Unfortunately, further exploration is going to have to wait for the weekend, but I will post what I find.  Again, thanks for your assistance.

Alex
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DHnut
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« Reply #6 on: February 02, 2017, 04:24:36 AM »

Another suggestion is to heat the copper pipe and aneal it before doing the soldering as many of the pipe fractures are due to work hardened pipes especially close to the head and the filler valve in the case of the Telco. I use a a pin to stop the solder running up the pipe as they are normally stainless or at least the ones I use. The O ring for the charging valve and the head I think are the same and are a standard size so should be available from a specialist supplier. 
I think the Gasparins use a soft sleeve silicon to seal on the inside of the conection, with the epoxy supporting the joint. It may pay to check. 
Ricky
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Martha
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« Reply #7 on: February 02, 2017, 04:43:17 AM »

DHnut - thanks for the advice - the pin sounds like a good solution to controlling solder flowing up the pipe.  With regard to your comment 'I think the Gasparins use a soft sleeve silicon to seal on the inside of the conection, with the epoxy supporting the joint. It may pay to check' - this may seem a really daft question, but how do you check?  Does the tank disassemble? The top section of the tank at the flare around the periphery of the land at which the pipes enter has a ridged finish which looks as if it is to aid gripping, there is also a joint line at the top of the cylindrical section of the tank. Forgive my ignorance, but does this all come apart? I had assumed that it was sealed during manufacture.

Thanks

Alex
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« Reply #8 on: February 02, 2017, 10:53:11 AM »

The tank head/pipe-fitting on Gasparin motors are screw-in (VERY fine thread).  Care needs to be exercised when disassembling/assembling so as not to cross or strip the threads.  Not sure whether an O-ring or other type of gasket is used.  The G-MOT series (commercially produced Gasparin designs) use an O-ring on the tank connection.
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GM
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« Reply #9 on: February 02, 2017, 05:10:11 PM »

Before resoldering the Telco pipework use a 20x magnifier as well as the water test to check that the tubing has not fractured. Soldering fractured tubing usually just creates a blocked piece of tubing. If there is any doubt I would unsolder the whole lot, cut the tubing a little shorter, clean the holes in the brass fittings  and tubing with the correct sized drill bit then clean everything very carefully before resoldering using the stainless pin technique.

All tanks for gasparin, telcos amd modella have a screw in fitting for the pipework, so yes the knurled edge is there to help gripping.

Early Gasparin motors had the tubing glued to the screw-in tank cap and filler valve using heat cured epoxy. To repair this you will need to remove all of the old glue then lightly abrade the surfaces and holes to give a key and then degrease everything. Use slow setting araldite and cure in the oven at 70 degress C for 45 minutes. Obviously this applies to the tubing and fittings only. The motor, tank, filler nozzle and any plastic inserts and o-rings must all be removed. Remember that before it cures the epoxy will initially get very runny so make sure it cannot run or drip in the wrong direction by orientating the parts appropriately.

I has this problem and resolved it permanently by making new brass fittings and soldering.

The telco uses standard size imperial BS o-rings available from any bearing supplier. You need to measure the outside or inside diameter of the ring and also the cross-section diameter of the rubber. I have this written down somewhere if you have no means of measuring.

The cylinder head of the gasparin uses an o-ring to seal the cylinder to to valve seat, and also a very fine piece of silicon tubing to seal the incoming pipework to the cylinder. If you have the instructions for the motor these are nicely shown in a drawing.

A photo of the modela tank would help.
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Martha
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« Reply #10 on: February 06, 2017, 03:55:16 AM »

A weekend of investigation has revealed that I need to source some 'o' rings for the Modela and the G63.  GM and Pit, thanks - as you say the tanks screw to the neck on these two engines.  I had forgotten that I had the exploded diagram as part of the Modela instructions and that clearly shows the assembly of the tank - I had convinced myself that it only showed the motor and never thought to check - senility strikes...  In both cases, taking it apart must have damaged the already poor seal further and despite lubricating and reassembling (just a faint hope) the leak was worse afterwards in both cases.  Clearly the parts need to be absolutely clean and in perfect condition to seal properly - no real surprise.  Unfortunately I don't have a spare in the supplied kits for either motor so it is going to require a search round the suppliers as has been suggested.  The Telco has yet to be looked at but serendipity being what it is, I was chatting to a old friend at the weekend (ex-aeromodeller owing to increasing age and infirmity) and it turned out that he has carried out the repair to the head inlet pipe on Telcos on a number of occasions in the past! He echoed everything that I have been advised here on the forum and offered further advice on soldering methodologies, so hopefully I am now all sorted.  Thanks again for all of the help

Best to all

Alex
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union model
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« Reply #11 on: February 06, 2017, 09:36:48 AM »

Simply Bearings are a good supplier for O rings

http://simplybearings.co.uk/shop/index.php?cPath=4501_4705
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Pat D
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« Reply #12 on: February 09, 2017, 10:08:44 AM »

Chargers, motors and spares are sold here

I've purchased a few of these and it's a good service

http://www.old-engine-model.com/en/k266.gasparin-co2-motory/

Hope this helps !

Pat
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Martha
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« Reply #13 on: February 10, 2017, 04:40:06 AM »

Hi Pat D, thanks, I had been looking at that site as an alternative source of motors and had seen that they also sell the adapters.  Unfortunately, the adapters that they sell are for bottles that do not appear to have the same mating thread-form as required for the (currently available in the UK) Alcojet bottle.  The Alcojet has a very coarse, square cross-section male thread-form on the bottle, requiring a female adapter with the same thread-form.  The adapters available from Old Model Co are either supplied with a more conventional 'triangular' cross section male thread (stated to be for a 'Czech bottle and which is therefore both too fine and of the wrong form for the Alcojet bottle), or are to suit a male thread on the bottle (ie female on the adapter) but are stated to be for a 'US 12oz' bottle.  This is the correct thread orientation for the Alcojet bottle, however, the research that I have done suggests that the Alcojet bottle thread is not the same as that on the 'US 12oz' bottle, such that those adapters are not suitable. I would be very pleased to be proved wrong on this as it would otherwise provide me with a solution!

All that said, Old Model Co (or Old Model Bazaar as they also appear call themselves) definitely have one of the best selections of (Gasparin) CO2 motors etc that I have currently found to be available!

Thanks for your help

Alex
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« Reply #14 on: February 20, 2017, 12:52:03 PM »

Martha, You should get in touch with Derek Knight,

http://www.kpaero.com, kpderek@btconnect.com, he can surely help you.


Luis
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« Reply #15 on: February 20, 2017, 02:37:24 PM »

I just received my adapter from Derek  Exceptionally fast service considering that he turns the units up per request and if he has material in stock.  You would do well to email him, but he WILL need to know what thread is used on your bottle.
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Martha
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« Reply #16 on: February 21, 2017, 03:24:48 AM »

Luis and Pit, yes thanks, as per my opening post, John at FliteHook has arranged with Derek to make me an adapter and I have emailed Derek direct with details however I understand that there will be a wait.

In the meantime I have water tested and disassembled the Gasparin tank collar and removed a very tired o ring at the neck/cap joint.  I noticed that one of the spare Telco o rings was a very similar size id and only marginally larger on od owing to a fractionally greater cross section, so I gave it a try on the Gasparin tank neck and it works perfectly.  That joint sorted, I set to and picked out all of the old epoxy used to 'pot' the inlet pipes to the filler cap and re-potted it (first of all having to get myself a set of binocular magnifier glasses so that I could adequately see what I was doing!).  The Gasparin leaks should now be fully sorted, fingers crossed.  I am off to the Shepton indoor session tonight to observe and learn, so testing will have to wait a little longer.  Roll on retirement and a few more hours for hobbies!
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