Patch News – November 2014

It’s already that time again. November seems to have flown by but it hasn’t included a lot of flying. It’s only to be expected that over the winter months we’ll lose some flying due to bad weather and that’s been the case in November, but we’ve also had some cracking days and some of us have taken full advantage. Not too many new models have been flown and we haven’t had any disasters worthy of Patch News so I’m a bit short of material. Come back Mick Harper, Mick could always be relied on to do something worth a mention! I can make up lack of material by waffling on about my own models, yes, it’s all about me!

First up is a model that’s never been to the patch, John Wheeley’s new indoor Extra. It’s another model from E-Flite, this one being Bind and Fly so all you need is a Spektrum transmitter to bind to the pre-installed receiver, and a 1s 150mAh lipo. Its full title is the UMX AS3Xtra, the AS3X part being Air Stability 3 Axis, a ‘system agility with flight mode flexibility’. Basically it has a 3 axis gyro that can be switched (using the Gear switch on the transmitter) to various flight modes that give you gyro assistance to prop hang, knife edge, and torque roll.The model itself has a laser cut foam structure that has been covered on one side in plastic film, so it’s a bit like building an open structure profile model entirely from ¼” square balsa and covering one side of the fuselage and the top of the wing with film. Dougal Entendre was kind enough to send me a photo of John looking very pleased with his new toy and reported that after just a few minutes flying John was prop hanging with the experts. I, of course, was rude and exclaimed that the electronics were a miracle maker! The gyro system is a developed version of the one MMM (alias Cyano Steve) has in his E-Flite UMX Sbach 342 3D that I featured in Patch News in March this year, I suspect we’ll be seeing a lot more gyros used in our outdoor flying machines soon. Keith Evans is using one of the HK Orange combined receiver/gyro units in his little EPP combat Mustang and holds it in high regard. Speaking of Cyano Steve, where are you, we haven’t seen you at the field for ages. I really do recommend you have a look at the Horizon Hobby video of the Extra here

This year the trend at the patch has been the little ‘warmliner’ gliders from HobbyKing, either the Spirit Mini Sport or the Kinetic. The two models are almost identical, there are some very minor differences but nothing very significant and they seem to perform just the same. They are fitted with different motors but neither seems better than the other and I think any difference in performance is due more to the type and age of the battery being used than anything else. Certainly there is a performance difference with mine depending whether I am using one of my newer or older packs. I seem to get flights of around 10 minutes with mine without trying and have had over 15 minutes a few times when I’ve concentrated a bit more on gliding rather than careering around, and I reckon considerably longer would be possible if that’s what you’re into. On one flight Dougal flew for so long his transmitter screen went into screensaver mode, fortunately that doesn’t affect the model control! November saw another Kinetic purchaser, Bob Hill. I think Bob has the rates/expo turned down so it’s not too lively for him and he seems to be getting on well with it. I’ve lost count of the number of these in the club now but off the top of my head I can think of six. There are probably more, it would be fun if we could get them all in the air together one day, although that would require a one off dispensation of the ‘max four in the air’ rule. Maybe it’s something to think about for next spring?

John Warren is one of the real builders left in the club and he’s just built and flown his latest masterpiece, this one being a Mudry CAP 20L. John built it from the Peter Miller plan in the March 2014 issue of RCM&E and it was designed to have a .25-.32cu in I/C engine. John has converted it to electric and used the motor that came from his old trainer and a 3 cell lipo. I had the pleasure of doing the maiden flight and am pleased to report that it went very well. The full-size CAP 20L was designed by Auguste Mudry as a single seat aerobatic version of the two seat CAP 10, basically it’s a CAP 10 with a greatly slimmed down fuselage. John’s model performs well and, like the full-size, is fully aerobatic and it should serve John very well and in particular it should improve his aerobatic flying lots. Now you know it flies well John you must add some trim and registration marks to make it look more scale.

I have a CAP 10 that I last flew about three years ago when I was using the LiFe cells and I need to do some conversion work so I can fly it on a 6 cell lipo pack. LiFe cells are much safer than lipos and can be charged at up to 10A whilst still in the model as they don’t catch fire. Mine were buried in the nose of the model and I used to recharge in about 20 minutes at the field from a leisure battery. My switch to lipos will mean I have to cut an access hatch somehow. I must get around to it as it’s a nice model and flies well. This airborne shot was taken by Gentleman Jim.

One of the problems with converting models designed for I/C to electric power is working out what motor/battery/prop to use. There are various calculation programs on the internet that can help you. Usually you put in basic model details and then you can play around with motor parameters and the program will predict how the model will fly and suggest propeller sizes. Some list many motors so if you have a particular one in mind you can see how it will suit the model. Keith Evans is another real builder and he uses a program called Webocalc which works well for him. It’s a free download and if you Google it you’ll see there are two versions, imperial units or metric. It’s a fairly simple program so it’s very easy to use, unlike some of the more complicated programs which seem to be too complex although they presumably give more accurate and detailed results. Find Webocalc here

Keith was good enough to send me a couple of photos of his latest model, a Citabria Pro based on a Tim Hooper plan from RCM&E.

It looks as if it’s almost finished now so should be gracing the skies over Chidden Down very soon.

Last week I bought one of Viv Burgess’s cast off models, a Yak 52. Viv built it a couple of years ago and I’ve flown it once or twice, it always seemed a nice flier. Viv had offered it to me a couple of months ago and I declined without really thinking too much about it. But Steve 1066 Hastings bought it and when I saw it again it reminded me of how nice it looks, and Steve kindly sold it on to me. It’s a VQ Models ARTF from HobbyKing, although Slough Models also sell the range in the UK. I know this as my CAP 10 that I mentioned earlier is a VQ model from Slough. It’s the relatively unusual TW (Tail Wheel) version; most Yak 52’s have a tricycle undercarriage. Some have been converted to tail-draggers but the factory did produce some like it as well. It’s a fully aerobatic aircraft capable of every manoeuvre in the Aresti catalogue. The VQ Yak 52 comes ready for either I/C or electric power and Viv chose the electric route using a 4260 motor of 500Kv fitted with a 14 x 10 prop. The model is 1500mm (59”) span and weighs just under 2.9kg (6lb 5oz) so it’s no lightweight. Steve reckons Viv flew it on 4 cells but 500Kv seems very low for 4 cells so I did some checks and found it was pulling around 440W, which equates to around 70w/lb. That would probably fly the model ok but I thought it might be a bit marginal for decent aerobatics, although I don’t remember it being underpowered at all when Viv owned it. I tried a few different props and found I could increase the wattage with a larger prop but the thrust seemed worse (the revs were dragged down too much). I wondered if Viv had been using 6 cells rather than 4 but I don’t know. After much dithering I swapped the motor for a 4250 6 turn 900kv Overlander Thumper that I bought in Mick Harper’s auction and decided to test fly with a 13 x 5 prop which appeared to provide loads of thrust. Because the new motor is 10mm shorter and a bit lighter than the original I had to drill more holes in the cowl to shift it back 10mm, and of course all this meant the CG would be heading rearwards, especially if Viv had used 6 cells rather than my 4. I was beginning to wish I’d just flown it as it came! I had no idea where the CG should be or what movements to set on the control surfaces and failed to find any answers on the web, so I taped a piece of lead to the cowl and guessed the control movements for the test flight. All went well apart from being very twitchy on the elevator (CG or too much movement?) and the stall seemed pretty tame. The telemetry recorded that I had pulled over 78A at full throttle so I decided to avoid that if possible! The second flight with reduced elevator movement and more expo was much better, it leapt into the air after a very short run and I didn’t get anywhere near to full throttle. I’m now even more convinced I should have just left the set-up alone! Thanks go to John Wheeley for the photos.

Since Sunday I have filled the redundant holes in the cowl and ended up repainting the whole thing. I’ve also extended the battery mounting plate so I can have the battery much further forward and ditch the lead. I’m going to try a 12 x 6 prop next time in the hope of reducing the amperage. It’s kept me quiet for a few days and I think it should be a great flier once I’ve sorted it to my liking, watch this space.

The last new model I saw in November was Desperate Dan’s new Acro Wot. He must have been impressed watching Nigel Baker flying his and decided he’d like one. Like Nigel’s it came with the usual ARTF (Almost Ready to Fail) undercarriage and it duly departed with almost no help from Dan. Chris Foss designs are great fliers but why can’t the manufacturers make stronger U/C mountings? It’s not just the Wot series; many ARTFs have pathetically weak U/C mountings. I think they are only test flown by expert pilots on huge billiard table tarmac runways. Come on guys, think of us poor lot flying from a small circle of (sometimes) rough grass.

One final photo, our Chairman Ron and Vice Chairman Alan enjoying flying together in the November sunshine.
 
Tony Blair, Margaret Thatcher, and Nick Clegg are all killed in a plane crash. They go up to heaven and face God sat on a great white throne, He addresses Nick Clegg first “Nick, what do you believe?”
Nick Replies “I believe the internal combustion engine is evil and should be banned, we must cut CFCs, and if any more Freon is used the world will become a huge greenhouse and everyone will die.”
God thinks for a second, and then says “OK, I can live with that, come and sit at my left side”. He then addresses Tony Blair “Tony, what do you believe?”
Tony replies “I believe in the power of the people, I believe people should be able to make their own choices and nobody should be able to dictate what others must do.”
God thinks for a second, and then says “OK, I can see that, come and sit at my right side.” He then addresses Margaret Thatcher “Margaret, what do you believe?”
“I believe you’re in my seat”
 Colin Cowplain