Here is a list of all the postings Gary Manuel has made in our forums. Click on a thread name to jump to the thread.
|Thread: Wot4XL Mk2 engine choices|
Try page 15 of the WOT4 XL manual
|Thread: Best bicycle tyres|
I have used Schwalbe Marathon Plus tyres for quite some time on my Brompton. Never had a single puncture after suffering regular Autumn punctures with normal tyres.
They are quite expensive but worth every penny. You can run a drawing pin over without it reaching the inner tube.
Frustrating is one way of putting it Rich! Engine runs lovely and model flies great apart from this problem.
I'm hoping to get chance to test it tomorrow. I'll take the spare ignition unit and tools needed to change it if all else fails.
PS vent line loop is now on top of the tank rather than down the side of it.
Screwing the nipple into the threaded hole revealed a problem!
There is a small shoulder between the threaded part and the hex head, which prevents the nipple from being screwed in until the head is flush with the diaphragm casing. This is because the nipple is intended to be pushed into a plain hole rather than being screwed into a threaded hole.
My plan was then to screw the large brass nut onto the nipple, add the washer, then screw the assembly into the casing..... but there's still a problem. The brass nut does not fit flush up to the nipple hex head for the same reason that the nipple didn't screw flush into the casing - due to the shoulder on the nipple.
To get round this little problem, I used a ball shaped grinding wheel in my Dremel and cut a recess in the brass nut to accommodate the shoulder on the nipple. That's better. I assembled these two parts with a strong thread-lock.
The nipple assembly and washer were then screwed into the diaphragm casing using medium thread-lock and the solder on the outside tidied up a bit with a Dremel / grinding wheel.
Inside tidied up in a similar way. The small length of the threaded part of the nipple was also ground flush with the casing.
Modified diaphragm casing reassembled onto the carb.
Tube pushed onto the nipple and routed down the side of the engine box ......
..... into the fuselage. I decided to route it into the fuselage rather than the engine box to keep it away from any moving air associated with the carb air intake. I didn't bother with the 35mm film can because I think the air should be fairly static inside the fuselage as there are no deliberate air holes in it.
Edited By Gary Manuel on 06/04/2018 17:51:58
I've changed my plans due to the weather and because the pressure nipples and M4 Taps arrived this morning.
I've decided that rather than flying without the cowl on, I'll do the carb diaphragm regulation mod first, see how it behaves, then tweak the mixtures and leave the ignition unit till last.
This is one of the nipples I'll be using. It's not quite what I thought I was ordering. I assumed that the gasket washer would fit between the small nipple head and the casing and that I'd discard the nut. It doesn't - it's obviously intended to be fitted with the nipple on the outside, flush up to an unthreaded hole in the tank, with the washer and nut on the inside of the tank. At this point, I thought that I would just make a smaller washer out of some suitable gasket material, but it didn't quite work out that way.
This is the diaphragm casing I'll be modifying.
Casing removed to reveal the diaphragm.
The existing vent hole blocked with solder from the inside .....
..... and the outside.
2.5mm pilot drill followed by 3.2mm. The final hole should have been 3.3mm to suit the M4 taps I'll be using, but 3.2 is the nearest I had available.
Hole tapped with an M4 tapered tap.
Continued in next post ......
Edited By Gary Manuel on 06/04/2018 17:48:47
I'm not ruling anything out yet because I simply don't understand what's going on.
In my head though, I'm reasonably satisfied that it's not the fuel supply that's causing the problem. That's why I'm concentrating on the air / fuel mixture and the ignition spark.
I couldn't find the specs for setting the plug gap for the AGM55 when I installed the plug, so I set it to 0.018" as specified for the very similar DLE55. I've just checked it and it's still 0.018".
The vent exits the bottom of the fuselage just in front of the undercarriage (about 4 inches in front of the tank).
I'm willing to consider anything, so I'll move the loop to the top of the tank rather than the side. It might help it to drain better if nothing else.
Plug looks OK Ron (Pale straw). It's an NGK CM6 - I never use the supplied ones.
It was a bit wet with un-burnt petrol though.
Edited By Gary Manuel on 02/04/2018 16:54:57
Cymaz - The filter was added in an attempt to address the initial problem described at the beginning of the thread. I've never used them before, but I'm pretty sure it is doing no harm - only doing good.
Key fob camera sounds like a good idea. I don't have one, but I might have to get one (or borrow one) if I can't cure the fault.
It's not as long as it looks in the photo Denis.
It does not reach the rear of the tank with the stopper fully in, even though it may look it in the photo.
Absolutely certain. I can see the clunk about 1/2 inch from the bottom of the tank.
Thanks for the suggestions fellas - I'm still open to further ones.
Edited By Gary Manuel on 02/04/2018 16:20:43
Posted by Percy Verance on 02/04/2018 13:10:52:
This thought went through my mind. I considered it unlikely but I'm not ruling anything out at this stage.
As it happens, I have a spare one of those I can try. The only issue with this one is that the plug cap is larger than the other one and will probably need a hope cutting in the cowl to get it to fit.
Plug cap has been checked and is on properly.
All fuel pipe is wide bore. The engine also runs OK at full chat whilst climbing vertical or 1/2 throttle prop-hanging, so the pump and piping appear to be OK. I don't think that this is the problem.
Here's a few photos of the installation.
The offset leg of the T goes to the fuel dot.
Here's the in-line filter. It is the car type, but I think the size is OK for a 50cc model. Note that it's still full of fuel even though the fuel tank has been emptied, so that appears to be doing its job.
Clunk pipe to T to filter to carb.
Fill pipe plugged with a fuel dot to prevent air being introduced here.
Simple plumbing and everything is still in place.
Clunk line is flexible enough.
Here's what tests I think I'll do.
1. Leave the cowl off and strap the spare ignition unit plus battery (to maintain the CoG) to the engine box and see how it behaves.
2. Tweak the mixture a bit (I've already done a bit of tweaking but the engine should be more run in now.
3. Try swapping the ignition unit (with cowl off).
4. Add a pressure nipple, vented to the inside of the fuselage.
5. Strip the carb if all else fails - It's only when inverted, so I don't think it's this. This requires engine removal, hence my reluctance.
I'll post a picture or two later.
This thread isn't done yet!
I took my model with modified fuel tank / supply lines for a test fly.
As a reminder, it's now a very simple 2 line tank with a "T" in the clunk line to allow filling and emptying then an in-line filter between the "T" and the carb. As I filled the tank for the first time, I did so with the canopy off, so that I could see the fuel / air bubble in the filter. No fuel was visible until I rotated the prop in order to pump fuel into the carb. Once the fuel level reached about half way up the filter, it stayed at that level. This is because the filter is horizontal in the model and the air bubble was above the level of the outlet pipe. The engine started and ran OK with the air bubble like this.
To get rid of the air bubble, I nosed the model up with the engine running. The engine cut when the air bubble reached it. The engine started after a couple of flicks and now had a smaller air bubble. I held the nose up again and this time the air bubble disappeared without cutting the engine. I now had a fuel supply with no air in it, so I had a fly.
The model flew OK with no sign of cutting out, even during inverted flight BUT whenever I attempted any negative G manoeuvres, the engine would cut. If I didn't attempt any negative G manoeuvres, the engine just kept running (I had a 15 minute flight). I tested this several times and was able to predict when the engine was going to cut. Bunts will cause the engine to cut. Inverted spins will. Tight rolling circles will while inverted with down elevator pushed in. I got to the point where if I got the timing right, I could roll out of a bunt half way through and hear the engine start to splutter, but recover as I rolled out.
It sounds as though it's a plumbing problem letting air in doesn't it? But no - for each dead-stick landing I had, I checked the in-line filter and in every case, there were NO AIR BUBBLE. On one test flight I even restarted the engine where it landed - twice. It started first flick both times, and flew OK straight away. On another, I started with a full tank, took off and went straight into a bunt - the engine cut, so it's unlikely to be a problem of air getting in to the system. It's also been completely re-plumbed in a different way and is behaving exactly the same as before.
So where does that leave me? Absolutely baffled.
I have checked to see if any wiring could be moving around during negative G but all looks well. I've questioned whether it could be a fail-safe issue, but it's set to reduce throttle to a reliable tick-over and not to cut the kill-switch channel. I'll have another play around with the ignition wiring with the engine running in the garden to see if I can find anything.
The only other thing I can think of is that it could be something to do with air flow through the cowl behaving in a way to affect the pressure at the diaphragm. I'm going to get a pressure nipple and tap set and do the diaphragm mod although this probably voids the engine warranty. I'll also tweak the engine mixture a bit to see if that helps.
Running out of ideas now. Any other suggestions out there?
Edited By Gary Manuel on 02/04/2018 13:00:38
Change of plan.
The filters arrived this morning and I've added one between the "T" and the carb.
I didn't realise that Royal Mail delivered n a Saturday. Let's hope the weather man delivers on Sunday.
Edited By Gary Manuel on 31/03/2018 13:21:19
Just a bit of an update..
The one dead-stick I had that is still concerning me because I can't put it down to sustained nose down flying is the one that happened whilst I was doing a rolling circle. I was in an inverted part of the manoeuvre and had already done about 3 circles when the engine cut.
The only thing I can think of to explain this is that the two clunk lines wrapped around each other (as suggested by Ron) whilst rolling and caused the fuel supply clunk to be held out of the fuel. I don't think that this would happen for the spin manoeuvres but is quite feasible for the multiple rolls.
The new felt clunks have arrived, but the filters are still in the post.
What I've decided to do for this weekend is to re-plumb the tank as a 2 pipe system, similar to most of my other petrol powered models. The clunk line now feeds the carb via a "T" piece. The offset leg of the "T" piece goes to a fuel dot for filling and emptying the tank. The vent pipe goes from the top of the tank to the open vent pipe underneath the fuselage via a loop to the rear of the tank and back to avoid syphoning while nose down.
I'll test fly it like this to see if I still have a problem with nose-down spins and I'll also see if I can get a full run without the engine cutting for regular flying. I'll add an in-line filter between the "T" piece and the carb, when they arrive.
I can see that it's probably the same issue and that a longer fuel line would probably help here by providing more fuel between the tank and engine.
That's effectively what I'm hoping that adding a large in-line filter is going to do (in addition to filtering the fuel).
Interesting that similar issues can appear in different situations - that's why its good to get opinions from people from different backgrounds. Thanks for the info.
|Thread: R.A.F. At 100|
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