/Dev's blog - RC Groups
/Dev's blog View Details
Posted by /Dev | Sep 15, 2012 @ 05:15 PM | 3,016 Views
Finally managed to maiden the Tomcat today in a nice 15mph wind at my local slope. I finally finished the build last weekend, having been too busy with other things since I started the build in my last blog post. Unusually, the radio set up was pretty straightforward, mostly copied from my Sunbird set up. The maiden was completely uneventful - the initial settings were all pretty much perfect and the model seems to fly quite nicely.

I've attached a scan of my servo tray, which seems to be a pretty good layout for the available space. Anyone looking closely will notice that there is an indent down the right hand side - this is for the QC label which is glassed into the side of the fuz. If I were building another one, I would actually have flipped the tray over (indent on the other side) to give me more servo travel on the elevator than on the rudder.
Posted by /Dev | Jun 24, 2012 @ 02:02 PM | 5,305 Views
Back in early April, I ordered a Tomcat from OLE RC, after a few months of contemplation and occasional research. I was looking for a step up from my RCRCM Sunbird which has been the mainstay of my slope hangar for the past year. The Sunbird is a great model, but I have found that its size (1.5m span) means I can't fly it too far away before it starts to disappear. I figured something a little bigger might prove a little more versatile.

However, the cost of larger moulded slopers tends to increase quite dramatically and, with the odd exception, most bare 3m kits tend to start at around £550. That's before the cost of radio gear or anything else that might be needed to get the model in the air. So, the Tomcat looked like pretty good value at under £400 for the glass version, albeit only a 2.5m span. At the time, ordering from OLE RC in China was the cheapest option, but since then T9 have renegotiated their pricing, which is now much more competitive. Either way, the model arrived all the way from China in under 2 weeks and in perfect condition - great service, great price.

The Tomcat comes without any build instructions or recommendations for radio gear or settings - there is a reasonably comprehensive build log here, which was recommended by OLE RC in response to my query for a build manual. There is also a build thread here on RCG, which is more recently updated, but less detailed.

The first thing that strikes you about the model is how unnecessarily narrow the...Continue Reading
Posted by /Dev | Mar 02, 2012 @ 07:52 AM | 2,921 Views
After managing to get out for my first flying session of the year last week, yesterday was bright and sunny, and I took the opportunity to drive a little further afield from my usual local slope. I drove over to Callow Bank, which is the slope soaring home of the SSA. I have flown there once or twice before when I've been passing through and the regulars there seem like a nice crowd.

The wind conditions seemed quite light when I arrived, but there were a number of paragliders flying from an adjacent ridge, which gave me some encouragement. As it turned out, a quick measurement with my trusty handheld anemometer showed that the wind was actually averaging about 13mph. There was another flyer there who managed to get in the air first with a Weasel Evo while I was rigging my Sunbird and taking out the ballast slugs which were in it. The Weasel seemed to be doing OK, so I threw the Sunbird out and it gained height without issue. Callow Bank is a really nice site with great visibility and lift band for smaller models.

There was plenty of thermal activity yesterday with some decent, big thermals blowing onto the slope periodically. The paragliders on the adjacent slope seemed to be enjoying the conditions too. Eventually, I decided to bring the Sunbird in for a landing. There is a large, open, flat field behind the slope making landing at Callow Bank a doddle. My fellow flyer had disappeared by this time, leaving me on my own to contemplate why I was the only person left there on such a perfect afternoon!
Posted by /Dev | Feb 26, 2012 @ 01:58 PM | 2,775 Views
It seems a little early to proclaim the start of a new flying season for me, given that it is not yet March and the weather is still quite cold and unpredictable. I am a bit of a softie when it comes to cold or wet conditions - I would much prefer to be indoors practising on my Phoenix v3 flight sim. Phoenix was a winter purchase to replace FMS which was complaining about my new Windows 7 laptop. I can highly recommend Phoenix - a definite improvement over FMS and well worth the money. It works beautifully with my JR 11x Zero Tx.

I finally managed to get out to my local slope soaring site at the end of last week for a short flight with my Sunbird just before sunset. The temp was about 6C with a 20mph wind. It was my first outing since my last blog post in November and my Sunbird's first flight since I creased one of the wingtips sometime around August last year. I was pleased to find that the repair doesn't seem to have affected the flying performance and is neat enough that I don't wince every time I look at it!

I'm looking forwards to the summer and more nice weather!
Posted by /Dev | Nov 16, 2011 @ 11:47 AM | 3,566 Views
After 5 weeks of waiting for some decent weather, I finally managed to maiden my Ebay Piper Pawnee this afternoon. It has been bright and sunny all day with little or no wind - pretty much perfect after weeks of 30-40mph wind and rain. Ideally I would have liked a little bit more wind than the 2-3mph today, which would have helped slow the model down for landing.

The near-perfect conditions meant that the flying field was busier than I was expecting for a Wednesday afternoon. I think there must have been 8 of us there over the couple of hours I was there - very unusual for mid-week at this time of year! Fortunately, I had also taken my trusty P-51 Python with me also, so I was able to do a couple of 10-minute "sighter" flights to get my thumbs ready for the Pawnee maiden. There is nothing worse than trying to maiden a new model after a few weeks of not flying.

The first job I had to do on the Pawnee was to do a range check. For my small models, e.g. less than 30in span, I tend just to do a basic check to satisfy myself that everything looks normal. However, I have used an Orange 6ch Rx and satellite in this model and I really wanted to be sure that it was working perfectly before flying the model. I felt this was particularly important because this model weighs around 3lb and could obviously do a fair amount of damage if I lost control of it.

As it turned out, I was not happy with the initial range test because control faded (went to hold) at around only...Continue Reading
Posted by /Dev | Oct 15, 2011 @ 09:43 AM | 3,300 Views
After giving my newly acquired E-Flite Piper Pawnee a thorough clean earlier in the week, I have also now managed to finish off the radio and electrics set up on the plane.

The model came with Hitec servos all round (rudder, elevator, flaps & ailerons), a generic (RC Max branded) 60A Opto ESC and Emax BL2820-07 motor driving a 12x8 APC prop.

I have opted to use an Orange 6-channel DSM2 Rx and remote receiver which I had left over from a previous build. I have also chosen a Tipple 4500mah Lipo flight pack and 2000mah Eneloop Rx pack (required because of opto ESC i.e. no BEC). The separate Rx pack makes a lot of sense for this type of model, which weighs 2.1Kg / 4.5lbs AUW.

The only change I have made to the servo configuration was to swap the standard JR servo extension connections on the 4 wing servos for a Multiplex green connector, which prevents any issues with connecting the servos to the wrong channel on the Rx. For the observant reader, who will have noticed that 7 channels are required for 6 servos plus throttle/ESC, the signal wire on the 2 flap servos is bridged on the Multiplex connector (effectively a Y-lead) i.e. one Rx flap channel driving both flap servos.

Running up the power system on a wattmeter shows that the system has a peak power draw of around 450W at about 40A on my 3S flight pack at full throttle. That should give me a conservative flight time of around 10mins. I was slightly disappointed with the power output: 100W/lb is just about...Continue Reading
Posted by /Dev | Oct 10, 2011 @ 08:18 PM | 3,759 Views
I hadn't intended to buy any new planes for a while, but I came across this second-hand Piper Pawnee going for a pretty good price, complete with all the servos, motor and speed controller. I went and collected the model this evening and it seemed to be in pretty good shape - no major crash damage, just some evidence of a heavy landing at some point (repaired undercarriage, loose tailwheel, cracked canopy). My guess would be a bounce followed by a cartwheel and finally landing upside down... I didn't dare ask the seller!!

Having got the model home, I had a closer inspection - nothing major:
- Undercarriage needed properly straightening (irritatingly the undercarriage uses some horrible imperial size cap-head screws )
- Elevator linkage had double-centre, which turned out to be due to a very tight pushrod linkage

I've also had to order a new lipo to test the model, since my current lipos are all too small by some considerable margin - this model needs around a 4200mah lipo. Once the battery arrives, I'll be able to finish the radio setup and get the plane balanced. The recommended CoG seems to be quite a bit forward of where I would expect... might need to do some research on what other people have found.
Posted by /Dev | Oct 01, 2011 @ 07:34 PM | 3,427 Views
The weather here in the UK has been unusually kind to us over the past week, today recording the highest temperature on record for October. Unfortunately, this has been accompanied by some pretty strong southerly winds which have been too strong for my electric models and the wrong direction for my local gliding slope.

However, earlier in the week I did manage to get an afternoon of sloping at a distant site about an hour's drive away in the Pennines. The slope is at a place called Marsden Moor, next to a pub called Nont Sarah's and is the home of the Marsden Moor Soaring Association (details here). There were a number of other flyers there - all very friendly and welcoming! Unfortunately I didn't take any photos, but it is a brilliant site and has a nice big landing area.

The wind died down enough this evening to allow me to take my Slipso for its second outing, this time at my local club field. Surprisingly, there was nobody else there, but that can be a good thing when you need some clear air to test a new model out fully. The other model I took with me was my P-51 Python which I built about 2 years ago. It is also designed as a pylon racer and is based around a similar power system to the Slipso, originally designed for a speed 400 motor. Mine actually uses an inexpensive CF2822 brushless outrunner driving a 7x3 prop.

The P-51 flies beautifully and is extremely stable in the air and was previously the quickest of my electric models. The motor will actually take...Continue Reading
Posted by /Dev | Sep 22, 2011 @ 05:47 PM | 3,103 Views
My Slipso is finally ready for its maiden flight! I'm waiting until I've seen it fly before I paint it - painting is a lot of trouble if the model doesn't fly right (ask me how I know). If all goes well, I will most likely use Klass Kote, which I have used before to good effect and produces a very tough finish.

Sorting out the ailerons has been the single most difficult part of the build. The plans are fairly vague about the best way to do them and the major limiting factor is that plate wing is only 6mm thick, which means that the servos have to be inboard, operating the ailerons via torque rods. My solution has been to use 2 x D47 servos driving the torque rods using mini ball links. The linkages all feel pretty solid and I am quite pleased with the result.

Current weight is around 310g (10oz) without a lipo. I am planning on using a 1000mah 3s lipo initially, which is a further 90g (3oz).

All I need now is for the wind to calm down a bit for the maiden flight...
Posted by /Dev | Sep 19, 2011 @ 09:06 AM | 3,300 Views
It may not look like I've made a lot of progress in the attached photo, but I have actually done a fair amount of work on the Slipso build:
- Covered everything in 2oz glass / epoxy
- Wet-sanded everything down with 600 grit, ready for priming
- Glued tail feathers
- Installed elevator servo and linkage
- Installed motor

Items left to complete are:
- Cut ailerons from wing panels
- Install aileron servos and torque rod linkages
- Make ply plates / fairings to spread load under wing bolts
- Radio setup
- Painting (but this is going to wait until after test flight!)

Overall, I'm quite pleased with the build. I may need to adjust the elevator linkage before the test flight because I think I may have made the control horn too small. I have ordered some ball links for the aileron torque rods, which I am currently planning to make out of 2mm wire; the main concern is to avoid any slop or flutter on what should be a fairly quick model.

The brushless motor I am using is a Black Mantis 2200kv, which draws around 20 amps from a 3s lipo with a 6x4 APC electric prop. The motor is a direct replacement for brushed speed 400 motor and fits directly onto the standard firewall which comes with the kit.
Posted by /Dev | Sep 11, 2011 @ 05:28 PM | 3,521 Views
My order of 1/4" triangular section balsa finally arrived yesterday from SLEC - great service for mail order balsa and ply in the UK. It's just a shame that the standard postal service with Royal Mail seems to be deteriorating - for some reason, my local delivery office only seem to deliver large packets to residential addresses on a Saturday morning now.

Anyway, I managed to make some good progress with the build yesterday evening and got the basic fuz completed and shaped. I still have a bit of tidying up to do with the final sanding / shaping and then I will glass everything next. I guess I am probably 15-20% into the build at this point.
Posted by /Dev | Sep 04, 2011 @ 05:05 PM | 4,948 Views
After the demise of my DH-88, I have a couple of 400-size brushless in-runner motors looking for new homes. My plan had been to build another P51 Python (plan by Mark Rittinger - see here for details). I built one of these about 2 years ago using a cheap outrunner setup and it has been an absolute delight to fly on every outing it gets, although it needs relatively calm conditions because of its small size.

However, whilst browsing kits on the Micron website, I came across a short kit for the Slipso 400. I originally downloaded the Slipso plans about 2 years ago (see here for the build thread), but never got around to doing anything with them. Seeing the short kit on the website reminded me that I had once intended to build one of these, so I succumbed and the kit was promptly ordered! I have bought a few kits from Micron in the past and their service was superb as usual, with the kit arriving in the post after a couple of days.

The short kit is essentially a few sheets of laser-cut balsa sheet for all of the main components of the model, plus a ply motor mount / firewall. I was slightly disappointed that there was not a printed plan included in the kit, so I had to print out my own plan on 6 sheets of A4 and tape them together - not a big deal, but it just seems slightly mean not to include a plan.

After clearing the workshop of my now fixed pressure washer (of which I now have more experience of disassembling and reassembling than I ever wanted), I finally managed...Continue Reading
Posted by /Dev | Aug 12, 2011 @ 07:41 AM | 3,571 Views
I had quite an interesting newsletter come into my email inbox earlier this week, which contained a short article about the increasing costs of raw materials and the impact on the price of the brushless motors we use in RC. I genuinely don't know how much truth there is in this, but maybe someone who knows better will comment?

Neodymium is a key component in Neodymium-Iron-Boron (NdFeB) magnets which are used in brushless motors and, essentially, the article was saying that the raw material cost of Neodymium has increased around 10-fold since 2009 and this is impacting the price of brushless motors. The example given was talking about a set of magnets increasing in cost from £8.50 to £70.00 for a medium size motor.

Personally, I am usually rather sceptical of these types of claim, which are typically just used to justify over-inflation price rises. However, there does at least seem to be some truth to the background situation which is that China is the largest producer of Neodymium and has recently introduced some additional taxes on production of the raw material and also introduced a new export quota. Does this equate with big price rises in brushless motors? I'm not sure - surely Neodymium is actually only a small constituent of the magnets and the overall cost of the motors? On the other hand, maybe we'll all be returning to IC in the next couple of years...
Posted by /Dev | Aug 12, 2011 @ 06:59 AM | 3,655 Views
There have not been too many nice flying days for me over the last few weeks and I have mostly been busy with other things on the days that have been nice.

Last weekend, the weather forecast for my local flying sites was not great and I was persuaded to go watch some F2C team racing at Barton Model Flying Club, which is not too far from home for me. It was quite interesting to watch something a little different from the usual RC flying I participate in, although I'm not sure I'll be taking up control line anytime soon though!

Whilst the weather has been unfriendly, I have been doing a couple of small jobs which I had been putting off for a while. One of these was to change the wing fixing for my Middle Phase from elastic bands to a screw fixing.

The model was built some 20+ years ago and I renovated it last year, converting it from 2-channel R/E only to 6-channel with full span ailerons and flaps. At the time, I added hard-points in the wing for screw fixing, but I left the original elastic bands while I sorted out whether the new wing configuration would work. It worked so well that I never got around to sorting out the wing fixing!

The screw fixing points on the fuz took a bit of pondering before I decided what to do; the main issue is that the fuz is completely open at the wing saddle, so there is no existing structure to screw into. The obvious option would have been to glue a couple of bearers across the fuz, but it is quite wide at the wing saddle and I...Continue Reading
Posted by /Dev | Jul 10, 2011 @ 12:51 PM | 4,709 Views
This time last year, I was busy finishing off my Cloud Models DH88. I had struggled with a couple of aspects of the build, but I eventually completed the model and it looked pretty nice - judge for yourself in the attached photo.

The maiden flight last August didn't go very well: the model had an extreme tendency to rotate very quickly along its longitudinal axis when launching, very much like a nasty tip stall. I spent a good deal of time considering and researching what the issue could be, eventually changing the CoG, motor and prop combination, prop rotation direction and many other minor tweaks. Nothing really helped and the model sustained lots of minor damage in the process of trying these tweaks.

A major breakthrough came late last year when I took the model to one of my local gliding slopes to try as a PSS model - it actually flew quite nicely, although it became obvious that it was perhaps a little too heavy and consequently quite difficult to slow down for landing (no flaps). This led me to the realisation that there was little fundamentally wrong with the wing build, tail incidence or anything like that. I went home pretty confident that I would be able to get to the bottom of the problem with the motors.

Wind forward to about a month ago and I eventually got around to taking the model out again for another try with the motors, this time with a hand-launch rather than RoG, which I had decided was the issue (my misguided deduction was that the model was...Continue Reading
Posted by /Dev | Jul 07, 2011 @ 08:34 PM | 4,062 Views
OK, I've been neglecting my poor old blog again - my excuses this time are (i) being away on holiday, (ii) being busy with work since I got back and (iii) consequently not getting much flying done and therefore not having a great deal to write about. This is definitely not good, given that the flying season for UK-based flyers should really be at its best around about now. I did manage to get out for a couple of hours with my Blaster 2 DLG last Saturday, just long enough for me to get sunburned on my face and neck.

That brings me round nicely to the subject of this blog post: spray painting. When I was building my Blaster 2, in the process of gluing the control snake outers to the inside of the boom (by running thin cyano down inside the boom), I accidentally let the excess cyano run out of the bottom of the boom and all over the pre-painted vertical stab. After doing my best to clean it up, it was left rather discoloured and in need of repainting. I finally got round to doing this yesterday evening.

I have to admit, I am pretty bad at anything to do with spray painting and am definitely no expert. In the past, I have tried using rattle cans and been very underwelmed by the quality and durability of the finish. Last year, I bit the bullet and bought a small compressor and a spray gun for a respray job on my D40. The reason I chose this route was mainly so that I could use a 2-part epoxy paint which would offer a much more durable finish for a slope model. The actual...Continue Reading
Posted by /Dev | Jun 03, 2011 @ 07:31 AM | 3,919 Views
I touched on this subject in my last blog, but I finally managed to get some data from my custom firmware on some real flights.

Just to take a brief step back and explain what Iíve done, I have been messing with the firmware (and hardware to some extent) on my OA to get some acceleration data from it. The idea was to use the data to try to plot the motion of the model during launch and get some extra data about my launch force consistency. In theory, this should help improve launch technique and with correctly setting up launch presets, etc. to maximise the launch height for a given launch force. I suppose the data could also be used to estimate a modelís attitude in flight and maybe even provide thermal detection (it should be possible to detect the upward/forward acceleration).

Attached is a photo of the test rig in my B2 DLG. The accelerometer is an ADXL345 on a Sparkfun breakout - the red square thing on the LHS of the photo. Now I know it works, I could actually shorten the leads and heatshrink it on the back of the OA main board with an insulation layer between the two boards. The only issue with that is that the accelerometer needs to be securely fixed to the airframe to give consistent readings, which would be a pain for accessing the OA serial connection for downloading data if it is screwed into place.

In terms of the technical details, the ADXL345 has a range of +/-16g in all 3 axes (it can also be switched to lower ranges for increased sensitivity) and...Continue Reading
Posted by /Dev | May 31, 2011 @ 04:56 PM | 3,702 Views
I have to admit I have been neglecting my blog for the past few weeks. But not by choice: I just haven't been able to get out flying. Anyone else who lives in the north-west of England will be familiar with the excessively strong winds and copious quantities of rain we have had for the last few weeks. I have only managed two short flying sessions, once with my D40 in 30mph+ winds and this evening with my Sunbird in 25mph winds. Both sessions finished early because I was just too cold to be comfortable for any length of time and it isn't worth breaking a model by being distracted by feeling cold.

Whilst the weather has not been so nice, I have been making productive use of the downtime to work on some custom firmware for my altimeter. Back in February, I bought an altimeter for my Blaster 2 DLG from OpenAltimeter so that I could measure my launch heights in an effort to improve my throwing technique. There's plenty of info on the website, but essentially the altimeter comprises a small microprocessor, some static memory and a pressure sensor. The latest version of the data downloader and graphing software can automatically update the firmware on the altimeter or you can independently update the firmware using the Arduino programming tool. Using this latter option, you can also build / edit / tweak the open source firmware. I now have a custom firmware running on my altimeter and will report back when I have been able to test it with some real flights - it's totally experimental at the moment, but it could be interesting! For anybody not interested in programming their own firmware, the stock firmware is excellent and very useful - I can thoroughly recommend it and it is definitely worth a look at the OpenAltimeter thead in the DLG forum for the latest info.
Posted by /Dev | May 06, 2011 @ 04:43 PM | 3,581 Views
I feel in need of a proper rant after something which happened today. I managed to sneak a quick fly at the slope this evening, but was interrupted by some paraglider pilots doing something insanely stupid - they arrived after I was in the air and proceeded to set up and launch half-way up the slope DIRECTLY UNDERNEATH where I was flying! Why would they do that??! Did they have a death wish? How exactly were they planning on keeping track of the model plane above them with their canopies in the way?

Don't get me wrong: I know there are limited number of safe slopes in the vicinity for any given wind direction and I am more than happy to share the slopes with anyone else who comes along. In fact, I will usually land my models to give the paragliders and hangliders time to launch safely and build up some height and/or we will agree who flies where. I simply don't want to be responsible (or even partly responsible) for an accident in which someone gets seriously injured.

So what was wrong with walking up to the top of slope today where I was flying from and letting me know what they were planning on doing?? Is it just me?

Rant over. At least I finally managed to test out the new flap settings on my D40, which now slows down properly. It's a long story, but I had to dig out the glued-in flap servos to change the offsets to get the right throws, which is why I had been putting up with not quite enough flap travel up until now! It was worthwhile getting it right - just wish I had done it sooner.
Posted by /Dev | May 05, 2011 @ 04:20 PM | 3,670 Views
I recently bought a copy of Radio Carbon Art DVD "Handlaunch Master Class 1" to help me improve my flying skills with my Blaster 2 DLG. What a great DVD! I had previously discounted buying this DVD because there is a great deal of free DLG setup information available right here on RCG in the Sailplanes forum and elsewhere.

The DVD is approx 1hr40 long and covers a variety of topics including:
- Checking initial model setup
- Radio setup (flight modes, mixes, etc.)
- Throwing technique
- Thermal hunting

Overall, I am really impressed with the DVD - there is a lot of useful content for someone like me who is a relative DLG novice flying a model which has already been setup per the manufacturer's (usually basic) instructions. I have already set up a few of the recommended tweaks on my model, including:
- moving the CG slightly back
- adding a Aileron -> Rudder mix for my thermal flight mode
- adding snap flap
- changing my aileron differential settings

I haven't tested these changes yet, but I am optimistic that this should help both launch and flying performance... time will tell. However, I already feel that buying the DVD was money well spent.

The DVD is available direct from Radio Carbon Art or T9 Hobby Sport if you are in the UK like me.