David Davis Posted August 9, 2016 Author Share Posted August 9, 2016 Do You Ever Have Days Like This? I replaced the fin on my WOT 4 XL and took the model to the flying field last Wednesday to test fly it. Several years ago, having worn out two Kyosho manual fuel pumps, I replaced them with an American Southern R/C "Six Shooter" pump, apparently these will never wear out and so far this has proved to be the case. However, as a pump, they are not as efficient as the Japanese pumps in that you have to crank the handle more to fill a tank of a given size. I was duly cranking away and talking to our club's only other Englishman, Daniel Hunn, the pilot who had been flying the model when the fin snapped off. I explained that the tank was quite large but it seemed to be taking an inordinate amount of time to fill. Puzzled, I stopped cranking and noticed fuel dripping from the undercarriage. "How has fuel got there?" I asked myself. I removed the wing and found out. The rubber bung from the tank supplied with the kit had worked loose and there was at least a centimetre of wasted fuel sloshing around in the fuselage! I had been warned about the quality of fuel tanks supplied with ARTF kits but had taken no notice! I inverted the model and threw away all of that fuel. In the process I covered the receiver in fuel and melted the glue on the velcro straps that were holding it to the fuselage. I screwed up the bung good and tight but deemed it unsafe to fly the model that day and had a couple of flights with my Stick 1500. Having removed as much fuel as I could with rags and kitchen towel, I left the rest to evaporate in the sun. I went home and found another tank. This was also supplied with some kit or other and had proved its worth. I see that it was produced by the "Super Flying Model Company." If you can imagine a white translucent tube with straight sides about 6" (15cms) long and 2.5" (6.5cms) high you'll have some idea of what it looks like. However, at the front of the tank there is an "ice breaker's prow" projecting forwards to prevent the fuel tubing from being crushed against the firewall in the event of ham-fisted construction or a sudden contact with terra firma! I tested the tank for leaks in the bathroom sink and it proved sound. I installed it in the model and went to the interclubs at Gueret with five of my colleagues. A sixth member was due to go with us but when we all met up prior to the journey to Gueret, we were told that his mother had died the previous day at the age of 83, after a long illness, so naturally, he would not be coming. We got to the Gueret Club's field and dealt with all of the bureaucracy as this was an event to which the general public were invited. All the pilots had to wear plastic bracelets for example. I unloaded my van and put the XL onto the stand, connected the pump to the filler tube and turned the handle. The tank seemed to take an age to fill but I persevered. Wary by now, I looked down at the wheels and there was the fuel dripping from the undercarriage! Off with the wing, the fuselage was swimming in fuel as before but the tank was empty! How could this be? Out with the tank, throw away the fuel, find some kitchen towel, ( the French were characteristically providing us with a four-course lunch for 10€,) dry the model off. Inspect the tank, no sign of a leak. Curious, I inspected further. This tank has the carburetter feed attached to the clunk line in the centre of the front face of the tank. Vertically above it there are two nipples, one for the fuel feed the other for the exhaust pressure pipe. In the past I must have used a two-pipe system on whichever model it was in because the lower of these two nipples was still capped off and there I was trying to force fuel into a tank through a blanked off feed nipple. Naturally I didn't fly it on Sunday either! Quote Link to comment Share on other sites More sharing options...
Geoff S Posted August 9, 2016 Share Posted August 9, 2016 Posted by Peter Christy on 21/07/2016 11:13:43: To my surprise, the model was way out of trim, constantly trying to dive sharply into the deck. And whilst frantically fumbling for the elevator trim - yes - I managed to turn the TX off!!! On most transmitters, this wouldn't have been a problem. I immediately realised what I had done, and switched it back on again! Unfortunately, this was a computer Tx, and it took some seconds to re-boot! Worse, I had programmed a "throttle cut" switch, and the Tx would only boot if the switch was in the "cut" position - which of course it wasn't because I was flying at the time! The poor old Wot4 spun into the crops, sustaining quite severe damage to the fuselage, though everything else survived OK. Pete I did exactly the same last year! I'd moved my Acrowot Foam e over to 2.4 gHz with my Taranis. I was using my Acrowot as a 'sacrificial tester' and the elevator trim needed more up. I wasn't used to the transmitter having moved over from my Multiplex 3030 and switched it off. I switched back on but, being a computer transmitter it complained about certain switches (including the throttle) not being to its satisfaction so didn't start transmitting for several seconds. I'd set the fail safe on the ground, which worked perfectly and set the elevator so that he model headed for the ground with the motor off! I hadn't intended the model to be literally a sacrifice I bought a new fuselage and motor (motor shafts were out of stock everywhere) for the Acrowot and it's flying again and I've fitted the neckstrap bracket so that the main switch is harder to reach. We live and learn. I now usually set elevator trims with a little too much up for test flights on the grounds that it's more comfortable to set the trim on a climbing model rather than on one heading for the ground. From Peter's other posts, I suspect his transmitter was also a Taranis. The switch on my 3030 is far away from the trims tucked away at the top left and moves sideways rather than vertically which was part of the reason for my faux pas. Geoff Geoff Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted August 9, 2016 Share Posted August 9, 2016 Another "Day like that." Getting ready to go flying I decided that I had better charge my starter battery, a 6 cell Nicad in my CMB starter. Then I found I had lost the adaptor. Nip up to the workroom and make a new one. Loaded up and off to the the flying field. When I arrived I found that had left my fuel at home. Making the adpator and charging the battery had disrupted my routine.. Only 6 minutes each way so off home to get it. When I tried ro start the model the engine refused to run, very strange, it would start and die. Eventually traced to the clunk having come forward and stuck in the tp of the tank. Can't get at the tank without major dismantling of the dummy engine and removal of the real engine. Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted August 9, 2016 Share Posted August 9, 2016 Spektrum DX7s have the switch close to the trim lever. Quote Link to comment Share on other sites More sharing options...
David Davis Posted August 9, 2016 Author Share Posted August 9, 2016 Posted by Peter Miller on 09/08/2016 11:25:42: Spektrum DX7s have the switch close to the trim lever. This is not a new phenomenon. I was flying a Detroit Custom Cruiser, (remember them?) years ago on a Sanwa Vanguard 6. I reached over to reduce the throttle trim, over-reached and switched off the transmitter! The receiver in the model then picked up the spurious signals from everybody else's transmitters, and ended up in the top branches of a tree. I had to hire a tree surgeon to rescue it. Quote Link to comment Share on other sites More sharing options...
onetenor Posted August 9, 2016 Share Posted August 9, 2016 Re brass pipes. Change for copper ( or Alloy ) The zinc / tin content of some brasses can be leached out .I was a plumber and often came across brass nuts the looked sintered and crumbled as soon as you put a spanner on them In fact they looked like copper balls in a nut shape Re switching off the Tx by mistake .All my Tx s have flush mounted slide on /off switches so this cannot happen. Some I changed my self Worth doing Quote Link to comment Share on other sites More sharing options...
onetenor Posted August 9, 2016 Share Posted August 9, 2016 Re brass pipes. Change for copper ( or Alloy ) The zinc / tin content of some brasses can be leached out .I was a plumber and often came across brass nuts the looked sintered and crumbled as soon as you put a spanner on them In fact they looked like copper balls in a nut shape Re switching off the Tx by mistake .All my Tx s have flush mounted slide on /off switches so this cannot happen. Some I changed my self Worth doing Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted August 9, 2016 Share Posted August 9, 2016 Posted by David Davis on 09/08/2016 12:28:05: Posted by Peter Miller on 09/08/2016 11:25:42: Spektrum DX7s have the switch close to the trim lever. This is not a new phenomenon. I was flying a Detroit Custom Cruiser, (remember them?) years ago on a Sanwa Vanguard 6. I reached over to reduce the throttle trim, over-reached and switched off the transmitter! The receiver in the model then picked up the spurious signals from everybody else's transmitters, and ended up in the top branches of a tree. I had to hire a tree surgeon to rescue it. I had a Custom Cruiser. Nice model. At least you got it back! My Minnow was a little ball of scrap balsa Quote Link to comment Share on other sites More sharing options...
Stuphedd Posted August 9, 2016 Share Posted August 9, 2016 High nitro attacks brass fuel pipes, I use nylon pipes same diameter and can be bent to any shape with a bit of heat .( makes plumbing much easier for tight places ) You can also heat the end to form a blob to keep the fuel pipe from slipping off , some of my "nylon tubed " tanks date back as far as the early 70s without a problem . Quote Link to comment Share on other sites More sharing options...
Rosco Posted August 9, 2016 Share Posted August 9, 2016 My story isn't as glorious as some of the others but........... ......quite a few times I've pulled the stick the wrong way after flying too many circuits inverted! I try to make a mental note when I first 'invert' but sometimes after I do a few inverted circuits, I get so into the mindset of being inverted that I pull down instead of pushing up without even thinking about it! Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted August 9, 2016 Share Posted August 9, 2016 d that many ears ago when the engne coughed while at fairly low level inverted and someone who will remain nameless did it with one of my designs a few years ago....I Never said a word. Quote Link to comment Share on other sites More sharing options...
David Davis Posted August 10, 2016 Author Share Posted August 10, 2016 Flew the WOT 4 XL this evening with a two-pipe system. This time I managed not to fill the fuselage with glow fuel! The engine started straight away and the model flew well. Fin modifications seem to have worked. Quote Link to comment Share on other sites More sharing options...
David Davis Posted August 10, 2016 Author Share Posted August 10, 2016 Posted by Peter Miller on 09/08/2016 11:25:42: I had a Custom Cruiser. Nice model. At least you got it back! My Minnow was a little ball of scrap balsa Was it as bad as this? Edited By David Davis on 10/08/2016 18:38:50 Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted August 10, 2016 Share Posted August 10, 2016 About the same 200+ feet vertically down at full power Quote Link to comment Share on other sites More sharing options...
David Davis Posted August 11, 2016 Author Share Posted August 11, 2016 Picture of the XL's repaired fin. Quote Link to comment Share on other sites More sharing options...
Peter Beeney Posted August 11, 2016 Share Posted August 11, 2016 Re. the fuel attacking the brass tubes within the fuel tank, it’s actually the methanol that is the culprit. This has been featured on the forum before. It happened to me many years ago and at the time I didn’t fully understand the reasons because I’d done a fair bit of of control line previously with all it’s associated homemade tin plate type tanks and brass tubes, that was always ok, but it soon occurred to me that the fuel is different; I was was playing with diesels then and their fuel is a mixture of oil, paraffin and ether, with a sprinkling of amyl nitrite or some such other exotic substance to taste. When I started to look into it I gathered the big users of methanol, such as dragsters etc., always replaced any brass components in the fuel system with items made from other materials first, usually stainless steel or similar, for this very reason. It was also difficult not to suspect that it had to be the methanol causing this anyway because I’ve always only ever used straight fuel, other than for some four stokes… I replaced mine with copper tube and this has never been been affected by the fuel, but I have read that in theory at least, methanol can occasionally cause copper and aluminium some grief, too. In my case the tube inside the tank had swollen up and split open, and it was a new model, from memory it happened over weeks/months rather than years. So, by and large, I would avoid using brass tube, (or what passes for brass tube these days), in any fuel tanks using methanol… PB Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.