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Tim Flyer19/11/2019 14:53:48
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1121 forum posts
214 photos

16414077-8454-4b32-8834-eb297ca1d473.jpegThe build is coming on now . The top is sheeted but cockpit cut outs need to be done . I have been also working on blending in the base of the wings with the nose floor. Quite a bit of sanding and grinding was needed to round the lower rear fuselage away 45bd4343-74aa-4d79-916a-934ebbe6a49c.jpegfrom its box section

Jon - Laser Engines19/11/2019 15:00:07
4900 forum posts
188 photos
Posted by Tim Flyer on 19/11/2019 14:46:44:

Cheers Applewood sorry I missed your post . I have a number of Laser engines and although ideally the spray bar is supposed to be at tank centre line , I have not had problems at all with centre line of intake at tank centre. The tall tanks (large tanks) can possibly lead to Syphoning on some planes but normally the fact that the undercarriage points the nose up stops ground siphoning . The other important matter is to properly tune the low speed needle setting. Many flyers leave their Laser engine low speed needle alone. It governs mixture up to around half throttle and does need occasional adjustment and should not be just left at factory setting. Jon at Laser is always happy to help with advice. A very rich low speed needle and tank a bit high can lead to cut out due to plug cooling.

I thought my ears were burning.

I tend to recommend the centre of the carb is no lower than the centre of the tank. Ideally the top of the tank should be in line as you then only have fuel below the carb and there is no change in head. A few mm higher is not normally a big problem though.

As Tim rightly says slow run adjustment is very important and often neglected. Dont be afraid of it, just lean off both needles as far as you can. Dont go 'a bit rich for safety', just lean it out. If the cooling is good enough and the tank position right then you will not have any problems. As a tuning guide, if it holds max rpm for 15 seconds then the tuning is fine. If it later stops its either overheated or gone lean due to fuel head changing. In this latter case, lower the fuel tank but leave the tuning alone.

Applewood19/11/2019 23:19:57
39 forum posts
Posted by Jon - Laser Engines on 19/11/2019 15:00:07:
Posted by Tim Flyer on 19/11/2019 14:46:44:

Cheers Applewood sorry I missed your post . I have a number of Laser engines and although ideally the spray bar is supposed to be at tank centre line , I have not had problems at all with centre line of intake at tank centre. The tall tanks (large tanks) can possibly lead to Syphoning on some planes but normally the fact that the undercarriage points the nose up stops ground siphoning . The other important matter is to properly tune the low speed needle setting. Many flyers leave their Laser engine low speed needle alone. It governs mixture up to around half throttle and does need occasional adjustment and should not be just left at factory setting. Jon at Laser is always happy to help with advice. A very rich low speed needle and tank a bit high can lead to cut out due to plug cooling.

I thought my ears were burning.

I tend to recommend the centre of the carb is no lower than the centre of the tank. Ideally the top of the tank should be in line as you then only have fuel below the carb and there is no change in head. A few mm higher is not normally a big problem though.

As Tim rightly says slow run adjustment is very important and often neglected. Dont be afraid of it, just lean off both needles as far as you can. Dont go 'a bit rich for safety', just lean it out. If the cooling is good enough and the tank position right then you will not have any problems. As a tuning guide, if it holds max rpm for 15 seconds then the tuning is fine. If it later stops its either overheated or gone lean due to fuel head changing. In this latter case, lower the fuel tank but leave the tuning alone.

Hi Jon and Tim,

so my tanks is 55mm tall and the centre of the carb is 18mm from the bottom of the tank. This makes the centre of the tank 10mm higher than the centre of the carb. Would you recommend getting the tank lower??

Tim Flyer20/11/2019 08:11:08
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1121 forum posts
214 photos

Best I can do is show you what I have done . Here is a photo with ruler showing cut out I made on bottom of former F2. I cut it approximately 15mm lower. If necessary I will be able to cut a maximum 10mm lower . I’m not going to do that until I have test run the engine. It’s hard to measure exactly but I believe the centre of my carb is fairly close to the tank centre. As I said I also slid my tank slightly rearward to accommodate the sloping air outlet duct from the firewall. 29f3ae61-9c6f-4a88-ad75-5a5e5805aa71.jpeg

Edited By Tim Flyer on 20/11/2019 08:12:39

Tim Flyer21/11/2019 20:16:35
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1121 forum posts
214 photos

I’m now making preparations for covering. I’m going to use Oracover and Solartex, and Halfords car spray for the cowl. Hopefully the car paint will allow Klass Kote fuel proofing without reacting . I’m painting the Balsa with diluted PVA to seal the grain and add hardness before covering. . I have painted the inside of the engine bay and front section with epoxy.

Edited By Tim Flyer on 21/11/2019 20:20:21

Tim Flyer22/11/2019 18:38:11
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1121 forum posts
214 photos

Today the fuselage got two coats of brushed “Clearcoat”. It is fuel resistant and helps film adhere well. It’s also very smelly so a mask was essential! It always seems rather like old fashioned cellulose dope.  I painted the tail fin stabiliser and rudder & elevator with two coats of diluted PVA. I think the wings will also eventually get the PVA treatment. My next job is attaching the wing fairings. These are ok but not very scale . I put foaming gorilla glue in them a few days ago to firm them up and give a better purchase when glued to the fuselage. I will make a stencil of the first before fitting so I can cut an exact size of red covering film around them . The fairings will be sprayed grey. I found some Halfords “Audi Laser Red” car spray which matches my Oracover Red film , and I will use that on the cowling. Hopefully Klass Kote fuel proofer won’t make it bubble. I will test first !

Edited By Tim Flyer on 22/11/2019 18:40:36

Edited By Tim Flyer on 22/11/2019 18:41:05

Tim Flyer24/11/2019 21:53:48
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1121 forum posts
214 photos

I have glued on the wing fairings now. Over the last few days I have filled them with foamy Gorilla glue which adds some strength to the soft abs plastic and provides a better surface to glue to the fuselage. I chose to glue them with wings removed after careful marking. This helps clamping and is easier to prevent messy seepage. 18756786-6dd0-4785-80ee-94f90805de32.jpeg

Tim Flyer24/11/2019 21:59:50
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1121 forum posts
214 photos

Preparation for covering is going well . The control surfaces have had a couple of coats of diluted PVA and sanding. The fuselage got clearcoat resin which gives a nice hard surface . I might give the wings the clearcoat treatment too. My new mask seems to filter the awful clearcoat fumes quite well so it isn’t too much of a problem using the cellulose based resin.

Ron Gray24/11/2019 22:34:58
1554 forum posts
367 photos

You’re doing a grand job Tim, I like the idea of clear oat as a fuel proofer.

Tim Flyer24/11/2019 22:44:41
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1121 forum posts
214 photos

Cheers Ron . The clear coat resin was a bit of a discovery a year or so back . I bought a big tin. It was made by solarfilm I’m not sure what the current equivalent is . I see Guild paints make clear finishing lacquer which might be similar? . It seems to be designed to help hold film edges down. It’s also great at sealing grain and iron on film sticks very well to it . I have found it extremely good to stick down and repair the cheapo covering on my Acrowot ARTF. This Chipmunk is getting “ “luxury” Oracover and the hollow panels will be Solartexed . The clearcoat dries in a couple of hours too. I still painted the inside and firewall with epoxy ( old habits die hard !)😊

Tim Flyer26/11/2019 17:00:09
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1121 forum posts
214 photos

I have started covering some of the bits that I’m finishing “off the model” . The fin and tailplane are both covered and I have installed the tailplane. The tail section with integral rudders are always a fiddle on Chipmunks. I might add a bit of epoxy to the rudder control horn to prevent any risk of it turning on the shaft. I have already ground a flat spot to help the grub screw engage and used blue thread lock. A loose rudder isn’t fun !

Nigel R26/11/2019 17:17:09
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3176 forum posts
487 photos

Clear Coat was great stuff.

No idea what I'm going to use in its place.

Build is looking good Tim.

Ron Gray26/11/2019 17:34:32
1554 forum posts
367 photos

I’ve got Clearcoat and only use it as a film edge sealer or as a base for film to stick to. Never thought of it as a fuel proofer though!

Tim Flyer26/11/2019 20:24:32
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1121 forum posts
214 photos

Hi Ron. I’ve really used it as a sanding sealer (thinned) on this plane and it’s great on balsa to help film adhere. I have given the whole fuselage two coats of it . I’m going to use PVA on the wings probably, but the clearcoat is much harder and resists dings. I think there are other cellulose clear resins around that could be similar. I will use it on the edges too. 

Edited By Tim Flyer on 26/11/2019 20:26:49

Edited By Tim Flyer on 26/11/2019 20:27:38

ASH.26/11/2019 21:30:17
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310 forum posts

Looking good Tim, I'm just surprised at the speed at which you build. You must be at it full-time!laugh

I have been extolling the use of 'Clearcoat' for years now -- for fuel proofing and sealing film edges.

I use it on the firewall inside and out, tank bay and inside of fuselage, usually two coats. It not only fuel proofs but seals and strenghtens the wood. It does add on weight so I must remember to take it easy next time. It is a synthetic resin made for the job. Also excellent for film edges, a painstaking task - well worth doing. Shame it's not made anymore, maybe Guild Paints Finishing Lacquer is as good.

Tim, I know you can't help epoxying fuselage insides.. Did you use fibreglass cloth as well.? What weight cloth do you normally use?

BTW, I love the bubblegum smell of Clearcoat.

Tim, if you haven't bought the Oracover and Solartex yet - have a look at Solarfim Glosstex. A smooth strong heavy covering.

Tim Flyer26/11/2019 22:38:17
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1121 forum posts
214 photos

Cheers Ash . I guess it does seem fast , but to me it isn’t really ...there are so many stages where glue has to dry etc. I guess that’s why I hate painting ( this is mostly going to be film covered). I have had much more time this year after stopping paid work although I’m not sure if that will be permanent . When I start a project I do find it hard to stop and I really try to keep to one project at a time as my workshop is very small and plane storage almost full now!
I have epoxied the inside with West systems Epoxy. It required just about 20g which is minimal weight . As this model is solidly built with liteply laminated sides plus various filleting on corners I dint need any cloth in the middle section. The sheeting on this model is also quite thick balsa. On ARTFs I sometimes use lightweight cloth on the inside sheeting where needed. Some ARTFs are ridiculously delicate.
On this Chipmunk nose section I used fibreglass tape similar to wing joining tape around the firewall and sides. It’s the same stuff they use to reinforce canoe joints and can be bought cheaply in long rolls ( canoe joining tape). I put in the engine blind nuts after epoxying the engine bay . That makes it easier . I also flatten the spikes on the blind nuts and just glue them in as the spikes can allow oil ingress plus damage and are not really needed. I am still using my supply of Solartex but noted your Glosstex recommendation. Thank You 😊

Edited By Tim Flyer on 26/11/2019 22:41:34

ASH.26/11/2019 23:08:39
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310 forum posts

Best way to do it Tim. Once a project is started it is best to carry on 'till completed otherwise it can drag on for ages.. months.. sometimes years!

Yes, looking at the pics I can see your previous boat building skills have come into use. The dark wood inside fuse looks like 'antique Teak'. laugh

Tim Flyer27/11/2019 06:49:40
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1121 forum posts
214 photos

Cheers Ash . Must admit I’m quite “allergic” to oil blobs on wood so its epoxy painted which adds lots of strength and rigidity.  I like to make the inside neat if possible too plus always put the of bit of triangular balsa gusset into the main stress points. I’m not keen on dry balsa . It just falls apart in the hands 😉

Edited By Tim Flyer on 27/11/2019 06:53:08

Tim Flyer02/12/2019 13:50:23
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1121 forum posts
214 photos

Things are moving along steadily now. I have covered painted and fixed the rudder tailplane and fin and just glued on the Long tail strake along the top of the fuselage (not sure what you call that!) . I will cover the tail strake next as that will be fiddly . I also fitted the instrument panels . These are rather nice for a kit I think. In the photo I lust loosely placed the canopy to make it look more “Chipmunky”. I used thin clearcoat as sanding sealer for the wings as I like the hardness it gives the balsa to stop dreaded hangar rash ! 7b31b92a-478d-4d07-8642-e58f7eb609cb.jpeg

Bruce Collinson02/12/2019 14:22:28
410 forum posts

You sure Andrew Hardman has sold out of Clearcoat? I had some from him earlier this year and agree, it's versatile stuff. Got some Balsaloc too. Could not get him to spill the beans on Prymol, what was in it, whether there's an equivalent etc. If anyone knows the answer I'll be grateful, as I'm sure will many others as Clearcoat is ok for sealing recalcitrant trim edges but I feel sure an etch primer would keep them stuck for longer.

Nice build BTW Tim, not been glued to it previously but clearly a project. Didn't succeed in maidening my P 47 which you helped with, got distracted by lots of elderly F3A planes and the UKCAA. Determined to sort it this winter though, the strip is very boggy so aviation opportunities are both scarce and short-lived.

BTC

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