Geoff S

I'm intending to use the panel mounted XT60 as the main battery connection not as an arming plug. When all I need to do is lift a panel to connect the battery I don't see the point of an arming plug which would be under the same panel. In fact, in most case, I see no need for anything more than the main battery connector if it's easily accessible. I connect the battery, do pre-flight checks and fly. I have a throttle disable switch on my transmitter (Taranis) which gives an audible message if it's on or off. Geoff

I remember the Le Mans disaster when 77 people were killed by one of the Mercedes works cars going out of control and into the spectators. Le Mans still goes on as does other racing events despite the awful tragedy. Perhaps one difference with the desperately tragic Shoreham event is that those killed weren't spectators but members of the public who just happened to be using a road adjacent to the airfield. Never the less the safety record of airshows in the past 50 years has been outstanding and one event shouldn't prejudice all airshows and certainly not penalise them financially to such a huge extent. I can't see how these elevated charges will improve the safety record. I can understand tighter regulation which may need slightly higher fees but this action seems to have as its primary purpose to reduce drastically the number of shows. Geoff

That's great news, Les. I maidened my DB Tiggie in December on the only decent day all month and it flew well with the CoG on that specified on the plan ie 100 mm back from the L/E of the top wing. It took a lot of lead to get it there so I'm hoping to remove ballast progressively to bring further back - perhaps by as much as 30 mm. Mine has an 870 kv motor with a 13x4 prop on a 4S 4000 mAH and 60 amp esc. My current telemetry told me it was drawing only 20 amps on level flight and up to 50 amps flat out. Here's to some better weather Geoff

In my case I was on the right model so model match wouldn't have helped. In addition to my little faux pas at the field my Taranis navigate buttons did the sadly all too common trick of disappearing into the case (it happened on my other Taranis). Then, to add insult to injury, I broke the fragile plastic as I was gently (as I thought) cleaning it with Ultraclens before glueing it back in place. Still T9 (hopefully) have come up trumps and some new buttons should arrive tomorrow. I've ordered a new complete fuselage from Inwoods. The Riot is one model I don't want to be without for long. The old one has served me well since just after they first came out (4 years ago? Time flies) and countless flights (200+) and 3 times as many landings (touch and goes) in all flyable conditions. It doesn't owe me a lot and it was pretty scruffy. I was going to get its big brother, the XL, but decided on the Tundra instead. Geoff

When I first started this aeromodelling lark I had just retired early (1995) as an electronics design engineer so electric propulsion interested me. It was really no place for a rank beginner with generally underpowered models with heavy NiCads and equally heavy brushed motors so I tried to understand what it was all about. My first efforts involved a spring balance fastened to the bench. I then tried to work out how much thrust you could get from a given prop at different speeds. To that end I made a table of propeller volume assuming 100% efficiency and then, knowing the mass of air I could determine how much thrust. I added a fiddle factor (I called it a propeller constant to be fancy) to allow for less than 100% efficiency. I even designed an optical tacho using a PIC which was also going to give thrust readings - the tacho worked but I never got round to programming the thrust calculations. I find the prop volume table quite useful in comparing the load imposed by different props eg a 12x6 prop has a volume of 678 cu ins/rev and an 11x7 665 cu ins/rev which means that they are both likely to be drawing similar current. I was strongly influenced by an article by Ken Nixon in IIRC Electric Flight back in 1997 or 8. Well, I guess that's why the idea of a motor test bed appeals. My professional life revolved around measurement and control, mostly on gas turbine test beds and rigs so I like the idea of transferring that to electric propulsion for models. Geoff

I don't buy the magazine regularly, at least the paper version, but I have tried a digital subscription in an effort to keep the shelves in my study cum workshop a little clearer. Funnily enough however I have 2 copies of last December's issue because I'm building a Ballerina (electric ) and thought I'd thrown out the magazine amongst a load of others I'd sent to recycling. After I'd bought a second copy the original showed up. Certainly, the panel mounted XT60 is illustrated but no mention of how you fix the connector firmly inside the holder. It needs to be able to resist both being pushed inside and pulled out as you fit and remove it's mate. There are no instructions so I'm not sure how it's intended to be applied. Geoff

I've now mostly converted to XT60 connectors. The nylon shells are excellent and seem to be very resistant to heat unlike some connectors I've used. The main problem is that some batteries I have, have wire almost too thick to go into the connector solder buckets and I had to pre-shrink the sleeving exactly to fit into the groove round the solder buckets. My 60 watt temperature controlled iron set to 450 deg C coped well with all the soldering. In all, it wasn't too traumatic. Now, has anyone used these panel mounting holders? How did you fix the plug into the holder? I'm thinking glue but which one? cyano? epoxy? uhu por? I'd prefer a mechanical fix but there isn't enough meat in the XT60 shell to drill a 2mm hole right though safely. Are there any better holders I haven't yet found? Geoff

My name is Geoff and I failed to check control movement and direction before taking off Which is something I thought I always did. Not in this case! My excuse is that it was cold and windy and it was a model I'd flown probably 200 times or more. I'd repaired the tail section of my Riot after the glue had given way last time I flew. It seemed I'd not reset the rudder push rod properly and had to mess about cheating by adjusting the servo centre with the transmitter rather than mechanically (I was going to correct that at home). So I took off and all seemed fine the wind was strong but not unflyable ... at least until I applied aileron input for the first turn! I've never flown a model with reversed ailerons before. I managed to turn it back onto the grass patch and effected a downwind landing not very successfully and did enough damage to render the airframe not worth mending. My Riot is the model I'll fly in any conditions and I was just checking the conditions before I test flew my new Durafly Tundra. I was on my own so just packed up and came home the Tundra still a virgin. I can't think how the ailerons came to be backwards. The servos are on a Y lead so can't be connected backwards. I can only think that as I was fumbling with the transmitter wearing gloves I accidentally reversed the output. But not a great morning despite the sunshine. Letters of either sympathy or derision gratefully received Geoff

Why am I regretting asking the question in the first place? Having said that, I wonder why static thrust tests are always performed on full size gas turbines (I know they are because I've seen lots and I assume the designers at RR know what they are doing) and is therefore a valid measurement yet the same test when the load is a propeller isn't. How about turboprops? Or turbofans both of which are run on test beds with load cells measuring the static thrust. How does an aeroplane 'know' what is providing the thrust - gas turbine, ducted fan or conventional airscrew? All generate the thrust by moving air mass. It seems to me the only difference between static thrust and that experienced in the air is that aircraft is moving forward and Andy has shown that, using telemetry, there is very little difference at the speeds we are interested in. My cousin's lad makes a living tuning engines for drag racing. He has a dynamometer as well as a rolling road. In neither case is either engine or the complete car moving. Not sure how the load is applied on the dynamometer but it could be an airscrew. Geoff Edited By Geoff Sleath on 09/02/2016 15:24:48

Posted by Bob Cotsford on 06/02/2016 16:23:38: The original kit version Great Planes Super Skybolt biplane has just two bolts to assemble it, everything else just clips in place. Very much the exception to the rule and also a long way from any sort of Moth type bipe. The DB 58" Moth isn't too bad. 2 bolts/wing and the undercarriage partly screws onto the bottom wing. The interplane struts hook on at the bottom and a long 14 swg pin secures the top and is fixed with an elastic band. So pretty easy and quick. But not quite 2 bolts for the lot Geoff Edited By Geoff Sleath on 06/02/2016 17:05:37

If anyone's interested I checked the current draw with the supplied 12x6 prop and 40 amp esc. 3S 2200 mAH 29 amps 320 watts 4S 3600 mAH 44 amps 620 watts So if you want to use 4S it looks like a bigger esc is needed - 60 amps? Geoff

I certainly wouldn't put my actual address in a model but a phone number and/or email address seems sensible. I don't do it. Perhaps I should. I lost my electric Lazy Bee some years ago. It went down wind and whatever I did wouldn't fly back and eventually I gave up and let it go in. I spent ages looking but never found it. I called at the farm in whose field I thought it had ended up and I got a phone call a few days later that it had been found. I gave the woman a big box of chocolates. The wing was undamaged but it was few years before I repaired the nose and got it flying again. The problem? The toothed belt drive pulley had lost all its teeth so the brushed motor wasn't driving the prop effectively. It's brushless now. Geoff

Of course there are plenty of warbirds that are also biplanes The biggest pain of a biplane is assembly at the field. I like biplanes a lot but they do have a tendency to become hangar queens unless you're determined. Geoff

Left hand threads are used in two places on pedal cycles specifically because of the possibility of their operation allowing them to unscrew ie the left pedal and the fixed (LH) cup of the bottom bracket. I think the smooth running of an electric motor resulting in a steady and smooth torque is likely to mean that reverse running is less likely to result in a prop coming loose. Perhaps quad fliers have found there to be a problem or they wouldn't go to the trouble of fitting motors with LH threads but I've never heard of a problem with fixed wing pushers run in reverse. Geoff

Well, as expected my Tundra arrived this morning as Parcel Force promised after failing yesterday. We seem to be on their early shift because they come between 0730 and 0800 when my wife and I luxuriating in bed listening to John Humphrys et al on the R$ Today programme. The walls on our old cottage are very thick and the chances of our hearing anyone knocking on the door are zero but I've installed a loud doorbell to overcome that. However, it seems PF's policy is not to ring doorbells for some reason! No wonder we get so many cards through the door when we've been at home all the time! OK, first impressions: Very well packed in its box wrapped in 2 large sheets of brown paper (saved for future use). The model components are fitted into a polystyrene moulding and it arrived after its long journey in good order apart from a little paint missing on the fuselage front. Assembly isn't too difficult and there's a very good manual written in reasonable English. There are lots of small self tappers in different sizes but separated in small labelled bags, which stops you from using the wrong size. Just follow the instructions and you won't go far wrong. Assembly pointers: 1: Fitting the undercarriage comes early but leave the wheels off to stop thing rolling about. 2: Read the instructions carefully. - I nearly forgot the carbon rod tailplane spar. 3:Take care when you first fit the wings. The aileron/flap connector is supposed to mate with one on the fuselage (no loose connectors needed ). In my case one wing was OK the other needed some careful tweeking before the 6 pins on the wing enterd the 6 sockets on the fuselage. Not a big problem but something to be aware of. 3: I set about fitting the optional tailplane struts which seem to be an afterthought as there's a loose instruction sheet for them. Unfortunately one of them came adrift from its plastic base so I've left them off for now. They don't say what glue to use. I tried Pound Shop cyano but it wasn't very effective. UHU Por might have been a more sensible choice. Both aileron and flaps are on Y leads. I chose to separate the ailerons as I have loads of channels on the Frsky X8R I have spare (it was originally intended for my Ballerina!). I've set up a little aileron differential and see how it behaves on the test flight. The flaps worked out OK and I've put them on the LHS slider on my Taranis which gives me 45 deg at the mid point and 90 at maximum. Most of the ball joint connections to the control surfaces were easy to click on with finger pressure. A couple needed a pair of pliers. The provided Velcro-like sticky back was used in the roomy area in the cockpit to hold the LiPo. I'm not happy using just Velcro for batteries having lost one in my Fun Cub whilst doing an outside loop so I've installed a strip of 10mm x 3mm hard wood across the fuselage over the battery held in place by a convenient rebate in the foam. I stuck some Diamond tape on the foam to protect it from wear. Some sticky back foam on the wood bears down on the LiPo and keeps it on the Velcro. Much more secure. Plusses: An attractive model of a type that suits me. Goes together well and seems to be well thought out Minuses: The after thought tailplane struts which don't have proper mountings like other parts The included floats. I'd rather have a cheaper model and buy them as accessories as the chances of my using them are slim. The big minus for me is the number of very small screws needed to assemble the model at the field. There are 4 to hold the wing in place (though the instructions say some clear tape is enough if you're not intending to fly aggressively) I have an idea to make that easier involving some 2mm carbon pegs in place of screws. There are a further 4 screws need to secure the working wing struts. So a bit fiddly with screws likely to get lost, particularly if you fly off grass. I'm looking forward to flying it but prospects are grim for the weekend. Next week perhaps? Geoff

Posted by Dave Bran on 04/02/2016 11:03:09: Posted by Dave Hopkin on 04/02/2016 09:42:42: Pans People Especially Babs............................. The guy who was the permanent skipper on the Rolls Royce yacht 'Merlin of Clyde' (a 54' ferro-cement ketch) was married to a former Pan's Person. Not sure which one it was because I never met her. Best job I ever had at RR in the 1990s was going sailing for a week every year as first mate all expenses paid (I never logged my overtime ). I don't think they got on all that well because he was never in a rush to go home when we arrived back in the Inverkip marina after the cruise. We used to take about 10 raw RR apprentices out for a week in the Clyde or Irish Sea and by the time we got back they were working as 2 teams sailing the boat (between bouts of sea sickness) Geoff

I don't like building in any components that may need replacing or, at least, some attention. It just goes against the grain for me. However, when I electrified my Limbo Dancer it was easier to fit the esc outside the fuselage in a safe place between the undercarriage legs. I have to take the wing off to replace the battery so I put the battery connectors through holes in the fuselage bottom which means I can replace the wing without the battery connected. It's an ugly model anyway so looks aren't an issue and motor is exposed anyway. It certainly keeps cool. Geoff

Posted by Jack Banner on 04/02/2016 15:23:26: I am glad to see some people agree with my concerns around safety being adhered to in these "infomercial" videos. Interesting to hear that you run a safety switch Geoff, is this on your TX or a physical switch on the model? My safety switch is just one of the switches on my Taranis but I had similar set up on my Multiplex 3030 without the voice reminder. The only minor problem with it for liquid fuelled models is that they won't start if I forget to enable the throttle I know some people use an enable plug on the model itself but I haven't done that yet. As I use 4mm connectors I leave one off until I'm about to fly but I'm about to go through the tedious task of converting to XT60 and that may change. Geoff

Well I passed the 76th yearly anniversary last month and I remember a lot of things that many today would find strange. No TV at all until I was 9 and then very limited hours. No Motorways until I was 19 Fog(smog) so thick that bus conductors (remember them?) had to walk in front of the bus to guide the driver Steam locomotives (I travelled to school behind one) Shopping with a ration book until I was 14 Pounds shillings and pence (thank goodness for decimalisation!) Computers without an integrated circuit or even a silicon transistor in sight and much too big to fit in the average living room. ( in my case ICT 1301) Analogue operational amplifiers integrated circuits costing 2 weeks wages and still worth using. Riding motor cycle trials wearing a cloth cap Geoff

Posted by Jack Banner on 03/02/2016 08:54:49: Best order some proper wheels for it. It looks like the supplied ones are just painted EPO. They're similar to the ones on the Fun Cub and mine have lasted several years though I use the grass rather than the tarmac mostly. I don't think they'll be painted; I suspect they'll be coloured right through. I think they'll be fine. I'll let you know. Mine was delivered this morning at 0745 when we were still in the bedroom but awake and Parcel Force didn't bother with the doorbell but crept quietly away. Hopefully it'll be delivered tomorrow morning and I'll be able to report on both quality overall and the wheels in particular I don't think it's overpriced. It's £140 delivered from the Euro warehouse and that's for a complete model ready to go after a hour's work ( 2 hours at most). My Fun Cub cost a lot more than that and needed a lot of work to get in the air. I take the point that the floats will not be used by most buyers and I think I would rather not have them and have the model cheaper but I'm not sure how much might be saved. I'm also happy to fit the push rods myself. One thing I have noticed in the reviews I've seen is the fact that Durafly got the flap servos in the right orientation to allow a single Y lead to one channel. You need a channel/flap on the Fun Cub. I also thought Dom was a bit casual fitting the battery as evidenced by the fact he accidentally knocked the throttle at one stage. A 12x6 carbon prop is not to be treated lightly if you value your fingers. I have a throttle disable switch on all my electric models and voice warning if it's not enabled. In fact I use the same switch on my liquid fuelled models. It's too easy to knock the throttle lever. Geoff

Posted by John F on 03/02/2016 13:56:23: Manchester University is doing interesting stuff with graphene capacitors here An interesting battery write up of a graphene based battery with real testing is here That article on graphene batteries is certainly interesting but confusing because of the units he uses. I'm old and I've been using metric units and centigrade temperatures for 50 years but it does get tiring reading US based technical stuff using early 20th century language. My head gets dizzy with conversions. He describes measuring IR and V of every pack and reveals the answer as 31 to 33 C. I have no idea what that means. I assume IR = internal resistance or Equivalent Series Resistance (ESR) which is usually measured in ohms and V is terminal voltage. Does anyone know how those measurements result in something measured in C (capacity?)? Never the less I somehow managed to work out that the capacity was maintained after nearly 900 cycles. Geoff

The ideal requirement is for the antennae to be mutually at right angles to each other ie one horizontal and the other vertical. Even in small, cramped airframes I've never found that to be a problem, even with the Frsky high gain blocks. With them I usually stick a bit of Velcro to the each antenna and another to the fuselage which keeps them in place but allows easy removal if necessary. Geoff Edited By Pete B - Moderator on 03/02/2016 13:03:02

Posted by John F on 03/02/2016 12:13:59: If you look at the hysterical warnings that some people give over li-po charging and warnings of the potential to level an entire house with the resulting explosion; imagine the underground bunkers that some people will build to accommodate the charging for these batteries!! Why do you think they should be any different from normal LiPos in their charge cycle? If the Effective Series Resistance (ESR) is lower then there will be less heat internally during the charge and presumably less chance of a fire. They're likely to be safer. However, I really would like to see some real data comparing their performance with standard LiPos. If HK stock them either here or in the Euro warehouse I'll certainly give a couple a try. They aren't much more expensive than standard LiPos and could be worth it if the number of charge/discharge cycles is as high as they claim. In fact they'd be cheaper per flight. Geoff

Yes Peter. I have a Multiplex Twin Jet somewhere hidden away and that was quite noisy with just a couple of 400 brushed motors in pusher configuration. I really should resurrect it. Wasn't there a free plan in one of the magazines some years ago for a small electric fanjet? IIRC it may have been a profile fuselage. Geoff

Hey! I thought you moderators were supposed to keep us in order and here's two of you encouraging very bad behaviour Passing air liners? There weren't many of those passing over Nottinghamshire in the late 1940s and in the early 1940s we would've been commended for downing the odd Heinkel. Geoff