microman

Thanks for that guys - really helpful!

Love the wee Corby - they perform brilliantly - even with a small VW engine which I am guessing is on this one - judging by the cheeks on the cowl.

I have a problem with the CHT in my Alpi (Rotax 912S). It seems that the gauge I mounted is incompatible with the Rotax sender and the readings I got (always in the green) were purely coincidental and bore no relation to the actual temperature. I need to either get another gauge which is compatible or use the gauge I have with a thermocouple under a spark plug. Anyone have any suggestions as to the best way to go? Another possible alternative is to get a gauge with a probe which would go into a hose from the radiator. That would give me an actual water temp rather than a cylinder head temp.

Will be interested in your thoughts on the A32 - have you flown the earlier model? We have a few here in NZ and they are highly-prized by their owners. Just how they are able to get so much more performance out of the A32 seems quite amazing.

Thankfully we here in NZ don't have to put up with any of that nonsense - apart from Auckland and Queenstown who appear to have banned microlights (probably fair enough as far as Auckland is concerned) as far as I know we can land at any airport (provided we have a transponder) without the need for any kind of security clearance. We do complete a "Fit & Proper Person" form when obtaining our license and there is some talk of making it a biannual thing but so far all good.

Hi James - I assume from your post that you are fully aware of the shortcomings of the original design and your Flea has been modified to avoid the tendency it had to enter an uncontrollable nosedive if you use more than 15 deg of nosedown attitude? I know they are still producing a modern version which is absolutely fine, but not sure what changes were made?

I have a huge affection for the Thruster - I learnt to fly in 1986 in an early 2-seater then bought my own single-seater. As a married man with a family struggling along with a big mortgage microlights were always going to be the only way I could ever get flying. The Thrusters were very strong, not difficult to land ( in spite of what some others have said), could handle some turbulence, and easily maintained. I modified mine so much it was barely recogniseable - cut down the ailerons, fitted fuselage enclosure, replaced the 447 with a 503 and added electric start (off a Honda industrial engine!) - all items which improved it - and became standard on later models.

Interesting - I have to plead guilty to every matter noted above - perhaps because I did the installation myself of the Rotax 912S in my Alpi. Are any of them critical do you think?

Perhaps thats because I only contribute when I have something relating to aviation which I think may be of interest to others - instead of mouthing off on political/religious issues. And yes - I like the jokes too!

I also totally agree with your sentiments Frank - this is an aviation site - not a forum for bigoted, left-wing, right-wing religious nuts who insist on airing their views on everything under the sun. In the end it becomes utterly pointless as extremists from both ends of the spectrum will never agree on anything so why even have the discussion?

Hi Jeff - welcome aboard - interested to know about your experience with Subaru engines - they were quite popular for a while here in NZ but in recent times have largely gone out of favour. Two Karatoo owners I know of both had Subaru engines - both had numerous problems and eventually gave up and fitted Rotaxes. The conversions were done by people who supposedly knew what they were doing but the engines just wouldn't hold together. Whats the secret?

We had a case here of a fellow who had recently soloed in his trike (still under instructor's supervision) - went flying low down riverbeds with his GoPro mounted on the wing - posted the results on UTube and now has a "please explain" from CAA!

I have an Icom 200 in my Alpi with a Skycom intercom fitted and guess what - exactly the same problem as skeptic36 - huge background noise on transmit (not all the time) - unplug the pax headset from the jack and hey presto - the noise has gone - can anyone throw any light on this problem? Radios!!!!!! I never seem to have one that works well - perhaps because I install them myself and I dont really know what I'm doing!

KRviator is right on the money - we have a couple of KR's here on the field and we call them the widowmakers - very light in pitch, very sensitive to loadings and not really a genuine 2-seater - 2 large people and you tend to stagger round the circuit in an arse-down attitude. Without flaps you need a mile of smooth runway to land, although once you are at altitude they fly beautifully - even on a VW. The nosewheel is one of its weaknesses - you certainly cant operate them on anything but smooth runways - no good at all on our rough grass strips.

I think you are reading too much into this - in my case I believe the throughbolt had been loosened at some stage in order to accommodate a bracket - and after the bracket was removed it was never tightened. It actually impressed me that the Rotax engine is so robust that the loss of a throughbolt didn't cause a problem.

I also found a throughbolt missing on my Rotax 912 ULS - it hadn't caused any problem - no leaks etc - but I fairly quickly replaced it!

I think most of us are aware that with any nosewheel aircraft you need to keep the stick back, allow the mains to drop onto the runway and then the nosewheel will drop of its own accord as the speed decays. Unfortunately both the Cheetah especially, and the Sierra to a lesser degree wanted to drop onto the nose much earlier - a clear sign that the maingear is too far back. You may get away with it landing on long smooth strips, but the rather agricultural nature of many of our strips means that any premature lowering of the nose can have catastrophic effects.

I also agree that Gary Morgan has come up with some great aircraft - although they tend to need some mods to really make them fly nicely. We have a Cheetah on the field and after the owner had wrecked two nosewheels and props we moved the mains forward 8 in to take some of the weight off the nose, replaced the main gear with ally leaf spring and reinforced the darn near useless KR2 nosewheel leg. Now it flys beautifully. We also delivered a Sierra from down south earlier this week and it also flys well - just needs a few little mods to improve it still further. With the Rotax 912S and in-flight variable pitch Ivoprop it gets up to nearly 150 kts and will cruise at 110kts at 4000 rpm

Just returned from a 3 hr flight back from Gore at the bottom of the South Island. Atrocious weather kept us grounded for a couple of days and in the end there was brief window between showers and we set off - unable to get over the mountains because of low cloud, so out to the east coast with a 2000 ft ceiling but also a 30 kt southerly pushing us along at up to 135 kts groundspeed - my mistake was to hug the shore and I copped rotor off the hills which felt like being in a washing machine but got out of it eventually and the rest of the flight was manageable if rather uncomfortable. Bit out of my comfort zone, but the Alpi handled it very well. Got home and found that a hatch behind the seat had dislodged in the turbulence and all the stuff there had ended up in the bottom of the fuselage - luckily no chance of fouling anything.

Hi Paul - when you are in NZ if you are anywhere near Nelson there is a flying school there which uses Sportstars - I'm sure they would organise something for you. If you would like more details closer to the date send me a PM and I will respond. Also, if you are near Christchurch I can introduce you to our local club at Rangiora - close to 100 microlights on the field of all types.

Can anyone help me with a simple weight and balance formula f0r the Sapphire? I have been playing around with different formulae but just seem to get tied up in knots. I know there is a simple formula available but cant seem to find it on the interweb.

Thanks for the advice - will do a weight & balance tomorrow - if its significantly aft I probably have no alternative but to remove the 503 and replace it with something much lighter - I do have a Kawasaki 440 available which should do the job.

Thanks pylon500 - You obviously have some experience of Sapphires - and 2-strokes - appreciate your input. You are right - the prop is not absorbing the power (even though its a 3-blade Ivoprop at full coarse) - due to its limited diameter - but I plan to get the 2.2:1 ratio gears and swap them - that should help, because not only will it give me some more revs at the prop but it should cut back the engine revs. Will also raise the needles as you suggest.

I have a single EGT - with the sender at the junction of the two exhaust manifold outlets - temps 600-650C so a little on the high side - have checked the carb slides and no issue there - I've gained 10kg since I last flew it (which probably compensates f0r the 10kg heavier engine) but I dont think thats the issue - stick pressure is negligible but tiny movements seem to have an exaggerated effect.. Will try for a richer mixture and see if that helps the mid-range.

Flew the Sapphire again today and only did one circuit - two issues - firstly the Rotax 503 runs smoothly up to 4500 rpm, then has a rough patch, surging etc, until it hits 6000 rpm and it takes off again - all the way to 7000 - if I let it go that far! My theory is that it is either running too lean or too rich in the mid-range and the circlip on the jet needle needs to be moved up/down (not sure which). Secondly, the pitch seems to be very sensitive - more so than I remember from when I last flew it 15 years ago. It is a constant effort to avoid overcontrolling and hence PIO. The stick is very short and I am contemplating adding an extension at the top to reduce its sensitivity. Any thoughts from anyone?