We are Hosting a May Bank holiday Jet weekend, 3 Full days of flying From Friday 8th May through to Sunday 10th May With May Day Bank Holiday being moved this year to the Friday we have decided to take advantage of this and include it in our weekend. Camping on site from Thurs 7th May 18.00hrs to Sunday 18.00hrs water & toilets on site. BBQ will be on every evening & you are welcome to bring your own food to cook. The J.M.A. are supporting this event so all current JMA members can camp & fly for free. Non JMA members the fees are Pilots £15 part weekend or £20 full weekend Camping £10 part weekend £15 full weekend. All fees payable on Arival. To attend this event you must pre book , Info required when booking is BMFA No, JMA No, if camping we need to know caravan or tent & No of nights. This is a closed event & not open to the general public. To book in & for anymore info please contact firstname.lastname@example.org Look forward to seeing you all there.
Well this is the bit where I say "Flew it today and flies really nicely", but actually it didn't. The day was cold and clammy, but not raining. A complete white overcast with the cloudbase down at about 300feet - not really ideal for first training flights with an aeroplane that has a completely white underside, but never mind.
Firstly I remembered to take some photos:
I should have put something in there for scale, but at 55" span this is quite a big model for a foamie. This is that huge battery bay under the canopy hatch:
I put it all together, fitted a battery and took it out for a test. Full throttle current on a fresh battery was 30A (measured with a clamp meter) - call it 340 watts for most of the battery run. It taxied well, steering was good and no ground-looping tendencies. It responded briskly to throttle and clearly had plenty of power. The take off was rapid with a little directional instability, but only a little (narrow track UC with the wheels well ahead of the CG, so not surprising). But I then found I needed half the available up elevator to fly level (far more than I could trim), so after a couple of quick circuits to check low speed control I landed. Approach was good, landing very straightforward.
I took it back to the pits and cranked in a lot of mechanical up trim. I started doing this on the clevis, but it left far too little threaded rod in the clevis so I moved the servo arm round by one spline. I'm not overly happy about this, so before the next session I'll make a longer pushrod and move the arm back to where it was.
Second flight was better. Elevator trimmed out nicely, but I couldn't seem to trim out the ailerons - it would wander off to one side or the other. Whether this is a lack of lateral stability, cheap servos or cheap Tx isn't clear. It's not a major thing - it's just that I like to be able to trim a trainer to fly the length of the strip hands-off and this one definitely wouldn't. But it was near enough and my daughter was champing at the bit to have a go, so I landed to connect up the buddybox. On this landing I tried the flaps. dropping them at normal cruise speed produces a massive initial pitch-up, but once the speed decayed the trim returned to normal. With the throttle shut and full flap it will do a 40 degree approach with no speed increase - they're powerful!
So we connected up the buddybox lead and did five training flights through the course of the day.My daughter did reasonably well, making all the usual mistakes and learning to recover from them. Given the difficulties (white model against a white sky, a slight blustery wind and lack of lateral stability) I think she actually did pretty well. A couple of times this got into the full death-spiral and I used full up (low rate) to recover - the wings stayed on, which was nice. These transmitters don't have timers on, and I forgot to start a watch, but I'd guess we were doing 15-20 minute flights and they took the battery down to between 12 and 18%. So I wouldn't want to use the recommended 2200mAh battery - not for flight training, at any rate.
My daughter then left to go shopping and I put the last battery in to go for a bit more extensive testing. I found a full throttle take-off would get a vertical climb for about 200 feet, and a 60 degree climb indefinitely. This is about what I'd expect from 300 watts in this size aeroplane. I also found that full (70 degrees) flap does actually boost the lift coefficient as well as add drag (which is actually quite rare) - with full flap I could hover over the centre of the runway in what I'm guessing was ~5kts of surface wind, so probably 10-12kts at 60feet. Loops and rolls were OK, but I found it flew better with a little rudder to help the ailerons. For training flights I may try putting in some CAR mixing to help. I still couldn't get the ailerons to trim-out. It also seemed to roll left slightly with either power or airspeed (not totally sure which) which implies a warp somewhere in the wing or fin, but I couldn't see it.
I couldn't resist the temptation to try out those tundra tyres, so I did a couple of touch & gos on the rough, unmown grass away from the strip which it handled well, and at the end of the flight I taxied back over the rough as well.
When I took the wings off to put it in the car I discovered that the end-fitting of one of the rear struts was loose in the tube. This MIGHT explain the wandering roll trim, but frankly I doubt it because the wings are torsionally stiff and I'm not convinced the struts do any structural work.
So as a sport model it's OK, and undoubtedly tweakable. But until I get the trimming problem sorted it's less than ideal as a trainer.
If I can respond to the queries as raised, PIF, don't do deer stalking at the mo, dodgy ticker following surgery so reverted back to r/c flying. My eldest son gave me his old volvo v40 when he upgraded and I keep it full of my modelling stuff, including planes, saves having to traipse them through the house. f3f all my batteries are life as I dumped my nicad/nimh batteries many years ago. The servos were sh1te anyway being jr and it was actually just 2 as both the wing servos and throttle servos were futaba which will function with life batteries. I'll not use them again as I prefer to use equipment I feel confident with. HT, keeping the core stuff, dumping all the models I've bent as at 75 I guess I'll never fix them now. It actually was a good move to remove the servos as the mounting plate for the rudder and elevator servos was broken so I epoxied in a couple of pieces of 3mm birch ply which is now secure, the wing servo mounting screws were just pushed in their holes so I pulled the old stunt of plugging the holes with trimmed and glued matchsticks to give the new modelfixing servo screws something to bite into.