You mentioned that you don't have a speed break or flaps. What is your
landing distance on concrete and grass?
Joe
On Nov 30, 2014 3:27 PM, "colin hales via KRnet"
wrote:
>
> Hi all,
> A couple of things. First, I'm too busy, articles, video editing, things
> are getting neglected, like my parents and friends. Lots to do before I
> return to America in January. My own fault so I try not to complain.
> I read a lot of the comments on Krnet.
> There seem to be a few repeating issues that I thought would reply to.
> Engine reliability.
> Non of them are. I wouldn't expect any light aircraft engine to do more
> than 500 hours without a good look over. I looked at one of my exhaust
> valves while repairing a leaking exhaust gasket. It looked rough, hardend
> plating corroded and cracked at base at 300 hours. I replace my exhaust
> valves each 300 hours now. If you don't, they will brake, or stick or both.
> Temps are vital, it took a long time to make sure my engine doesn't even
> get hot.
> Its not really the engine or designers fault. Its operating conditions,
> operators and maintenance. I've read many of the reports of the jabiru
> engine failures and sort of knew why most of them had happened.
> Lets get real. The Jabiru engine has had next to know research or
> development. During the early days, the owners were doing it. I learnt
> quickly about 5 vital things to look after my Jabiru, by seeing what
> happened to the operating parameters, temps pressures when various
> operating conditions were applied. None of them have ever been added to any
> news letter or information advice from the manufacturer and I've given up
> telling people now. No one listens.I even was asked to write an article for
> our society about Jabiru engines. I entitled it, "Jabiru engines and what
> they won't tell you about them!" Highlighting about 10 issues, 5 I though
> vital for safe operation of the Jabiru engine. They never published it,said
> it was too inflammatory and open to the layers...
> I know people will now say that they have had thousands of trouble free
> use from their engines, well all I can say to that is that , you are either
> a diligent operator and maintainer, or you have been lucky.
> The Rotax engine had a lot more development thrown at it, and you have to
> pay for that in the cost of the thing. Get what you pay for... The Jabiru
> engine is expensive as well, that's because you are paying for a decent
> power to weight ratio. That's all.
> Its no good really. Its still too delicate. I use it though, but monitor
> it and all four egt and cht parameters rigorously and check heads and
> tappet clearances for signs of change or deformation regularly. Seems to
> keep going. But I don't like it. I would love to buy one and not have to
> think it was ever going to quit for 2,000 hours as they say, but its a
> joke... Not funny when they do break and seemingly they do. Anyway...
> Next, speed brakes. A KR needs to be light and none complicated if it is
> going to perform well. I haven't got flaps or a speed brake. You don't need
> them. People keep saying that "They float!" How? Its got tiny wings! The
> problem mostly seems to be that people need a high throttle position to
> keep their poorly idling engines going on the ground at say, 700 rpm. This
> unfortunately turns into about 1,400 rpm in the air. No wonder it floats,
> thats still about 1/4 throttle. If you remove the idle stop for your engine
> all together, if you close the throttle completely, it now acts like a
> exhaust brake. The engine will never stop in the air, it just windmills at
> 500 rpm causing massive drag and the aircraft stops and falls out the sky.
> When you land and the idle gets lower as they airspeed decreases, just
> crack a little throttle back on. So don't worry about how many holes to put
> in your speed brake, save yourself a lot of time and weight and
> complication and use the prop as a brake instead. This only works if you
> have a starter motor, I've accidentally let it stop once or twice out on
> the taxi way. But its safer too. No panic trying to find mag switches or
> trying to turn mags switch keys, if a dog runs out, as has happened to me.
> Just pull the throttle, which your hand is on anyway and it stops.
> More ways to skin a cat, which is a funny saying we have here. I'm not
> telling anyone anything or want any reply or discussion with this message.
> I'm just saying what I do and saying that if you haven't tried it, give it
> a go. If it works for you too, brill, if not well, I reckon holes add to
> drag. About 20 two inch holes should do.
> Keep an eye on those engines, if you have a worry, you are probably right
> and you should take a look, it never hurts.
> Best regards,
> Colin Hales.
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