EvilC57

It seems so if you’re a ‘professional’ drone flyer. I’ve recently seen a couple episodes of a Channel 4 programme called Worst House on the Street, another one of those house transformation programmes that seem to be fashionable at the moment. In each episode, there seem to be a number of shots obviously taken from a drone flying around the subject house low over the roofs of adjoining urban properties. In fact I noticed a shot last night, which started high over a neighbour’s front garden across the road, and flew down, through the front door into the hallway, then into the lounge and back out into the kitchen. Clever flying (if it’s not TV trickery), and all presumably legal.

I agree with you regarding stories of estate agents flying illegally. However regarding authenticity of the story, try these instead… Wilts & Gloucestershire Standard, sUAS News or BBC News

In Cirencester yesterday. Read about it here.

Interesting you should say that. I’ve been looking at both the Freewing and FMS Yak130 EDFs. It seems to me that the FMS is of higher quality. For one thing, the FMS has proper sprung undercarriage oleos where the Freewing has simple wire retracts. I guess a wire undercarriage makes it cheaper, but am I missing something?

Ah yes. Thanks chaps.

I've recently noticed these marks on my 5m tape measure. A black shield at 16" and every 16" thereafter. A black diamond at just after 193/16" and just after every 193/16" thereafter. A black inverted shield at 40cm and every 40cm therafter. Any ideas as to what they signify please?

That's good to hear Jon 😀.

Another update by OP: Crank pin further cleaned up using some very fine wet & dry with oil as suggested by Jon in an earlier post. Engine reassembled, and then tested by having a tank full of fuel put through it at our field today (both right way up and inverted), as you can see below. On getting it home again, I removed the crankcase lower housing once more, and everything including what I could see of the crank pin appears to be covered in a fine coating of oil - which is good I guess! It’s now back in the model awaiting some more testing on the ground, to rebuild confidence before it takes to the air again. IMG_5335.MP4

I agree with you Jon about the half turn being madness. I’m talking about one or two clicks, that’s all.

Going back to this earlier post. May I just defend myself: By saying that I run engines on the rich side, I'm following the manufacturers instructions; in that as per the instructions for both 2 and 4-strokes, I run them slightly to the rich side of peak RPM when on the ground. I.E. In accordance with the following diagram, which appears in the instruction manuals for a number of OS engines. And also: The instructions for the RCV58-CD which say, "Main needle (high speed) adjustment: The main needle should be adjusted with the engine operating at full throttle. The engine should be leaned out until the RPM peaks, then enritched a small amount. This will allow for the leaning out that normally occurs in flight.". The instructions for an OS MAX-25FSR I also own, which say, (after running in) "After six to ten flights, it should be possible to run the engine continuously on its optimum needle setting. This setting is with the needle valve adjustment 1/4 to 1/2 turn on the rich side of the position at which the engine reaches its very highest speed. Your engine can be said to have completed its running-in period when it holds a steady speed at this optimum setting. Never attempt to gain a few more RPM by running the engine on a lean setting; it will run hotter and may eventually become damaged by over-heating.". I'm just doing what the books say 🙂.

Yes I did. I picked off the remains very delicately with a scalpel, and used a small soft wire brush afterwards. I didn't want to attack it with wet & dry and risk reducing the diameter. It looks (under a x7 magnifying glass) and feels completely smooth now. The brass washer from the crankpin was more of a problem. That had some stubborn deposits of aluminium from the old conrod on one side of it. This I cleaned off using very fine wet & dry (used wet) in a circular motion on the end of my finger against a smooth surface. Being careful to remove all the aluminium, but none of the brass. I can only do what I can do to ensure it's perfect during reassembly. If it fails again it'll go in the bin, and I'll turn my attention back to eBay for a replacement engine.

No I'm not sure. The cylinder bearing is running smoothly now, and my understanding of other people's efforts at replacing it leave me a little reluctant to try it unless I have to.

Right, time for an update and some questions. I decided after all that as it seemed only a new conrod was required, I’d go for a careful cleaning of the the engine, followed by an equally careful rebuild. I managed to remove the rotating cylinder with the aid of a heat gun, a small wooden drift and a rubber mallet. The large ball race then being exposed. This felt slightly gritty, and on washing it out I noticed a fair amount of what looked like aluminium swarf in the bottom of the plastic container I used as a bath. The bearing still felt slightly gritty but was perfect after being kindly blown out by a friend with a compressed air line. Fitting the new conrod with the lubrication cutouts at the front, as suggested by Martin Harris and others in the thread suggested by Manish just above, gives the conrod an offset toward the front of the piston (see pic below) - I know the crank pin circlip is not fitted yet. Can this be right if it’s not in the the middle below the piston? It could be argued that there should be another washer forward of the big end, however none was fitted originally, and no washers at all are shown on the manufacturer’s exploded drawing of the engine. Looking at the remains of the old conrod compared with the new, you could almost believe there was no oilway in the big end. Once the rest of the engine is sorted, I might try filing into the remains of the big end to see whether I can see any trace of the hole that should be there.

However, I've just remembered a thread I started here a while ago. Make sure the receiver has the latest software installed.

It would appear so. I took the pictures below while on holiday in Tibet a few years ago, where it is a sacred symbol in the Bön religion (a minority branch of Tibetan Buddhism), and predates its use by Germany by hundreds of years.

Yep, I have several of them in use with my DX8 Gen 1.

Yes, I’ll strip everything down as far as I can and give it all a thorough wash out; presumably in fresh fuel being the best thing. Unless anyone knows better, I can’t get the rotating cylinder valve out, as looking at the exploded diagram here it seems to be retained by a large circlip, which once installed in the upper crankcase casting, can’t be accessed to remove it.

Who knows? That was my thought too. As I said in an earlier post, it is inverted in the model. But the instructions specifically say it can be run inverted (like every other glow motor I’ve come across). I’m careful to run engines on the rich side. I’d rather have the reliability over absolute peak RPM.

I’ve just got around to having a closer look at the engine, having stripped it down a bit further. Damage appears to be confined to the conrod big end. Having removed the circlip and remains of the big end bush from the crank pin, the pin itself seems OK - maybe just needing a bit of a clean up. The inside of the cylinder and the piston seem perfect, with no scoring that I can see or feel. I called Weston UK yesterday, and they quoted £10.50 (inc VAT) for a new conrod, and £19.99 for a crankshaft - but I don’t think I’m going to need that. So for just over a tenner, I think I might try and get it going again, after a good bath and a cleanup to make sure I’ve got rid of any conrod debris. It’s still worrying though, as to how the big end came to seize in the first place.

Good point re routing the crankase vent back to the carb Manish, it would explain the threaded hole. As I've said in previous posts, I'm becoming less inclined to try and repair it, as it has an unknown history regarding fuel etc. I'd rather spend the money on what looks to be a better one on eBay or similar.

OK thanks for your suggestions Jon. The crankshaft bearings seem free enough at the moment, but as you say, they really need cleaning out to make sure. I don't have an ultrasonic bath, maybe I should treat myself to one sometime. As you say, it was only a tenner so I'm not sure it's worth all the effort of trying to get it going again. By the time I've bought all the bits that may be required (with no guarantee that they'll actually fix it), I'm inclined to wait and see what comes up on eBay in terms of what looks likely to be a good runner.

Some interesting points there thanks Martin, Jon & all. I’d observed that the crank pin looked dry, but (stupidly) dismissed it. Is it possible for the pin to be dry? If so, I guess it might also explain why the crank case bearings appear to have been spun. Yes the piston moves OK In the cylinder, so presumably we’re looking at lack of lower end lubrication - the engine is inverted when installed in the model, but they’re designed to run at any angle aren’t they. Well done for spotting the mod to the carb inlet, it appears to have been drilled and tapped for some reason. Buy hey, I only paid £10 for the engine as I say, at a bring & buy. But as they say, buy cheap, buy twice. So, if I get in touch with Weston to try and get a new con rod and crank shaft, bearing in mind the apparent lack of lower end lubrication, what’s to say it won’t seize again?

Another one broken! I was flying my large twin yesterday which has a pair of RCV58s in it, when after 5 minutes or so in the air the model seemed to lose power. I managed to land just short of our patch, with no damage fortunately. On inspection, one of the engines had lost its alloy spinner cap, and the prop was loose (which is what fooled me into thinking both engines were still running, as the loose prop on the dead engine was windmilling). All evidence of a sudden stop in flight. On removing the engine today, and splitting the crankcase, the big end has broken off and the crankpin appears damaged. The engine which failed was bought cheap at a bring & buy sale a few years ago (unlike its twin which was bought new), and reading Engine Doctor's post above (August 25th 2015), it seems the piston may also have got grabbed by the rotating cylinder and twisted off. The other engine has always been run on sythetic, but unfortunately I don't know the fuel history of this one, although I remember having to clean a number of brown castor stains off when I first got it. Seems the previous owner may have known something I didn't 😕! The decision has to be, do I try and repair it, or scrap it and turn to eBay?