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facthunter

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About facthunter

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  • Birthday 01/04/1940

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  1. Particularly in U/L applications where they get all kinds of treatment, and we are generally doing it the way we are to keep the budget (ours) in control. Nev
  2. What's so weird about a cotton thread (as well as compound) between the surfaces?. Its a common proven practice. Built up pressed together cranks are suss and there's been a few associated failures. The gear drive end is also subject to inspections . The cam faced friction damped shock absorber is fairly unique but needed and if there's metal or excess noise you pull it and have it checked.. I think you are a bit one eyed about your Rotax.. I'm not out to bag it for the sake of it but just add a few facts which is what we should be dealing with in these matters. Nev
  3. Gear redrives are not easy to design. The Rotax one is quite complex and requires (expensive) service occasionally. It's also pretty noisy and clunky, starting and stopping. One advantage of THAT red . gear is more choice of a prop and easy mechanical in flight variable pitch. Planes which operate under 110 knots don't need variable pitch prop. It all weighs and costs. The built up crank on a Rotax is an odd thing that I see as a downside. Just pressing parts like that together sucks. It's a known weakness. Torque equates to thrust which you need to get you moving Gears multiply torque. but there's a loss involved. Octane rating s vary because of more than compression ratio. Smaller bores can allow more compression to be used. A four valve head with central plug will run a higher compression as it needs less advance. IF you direct inject it doesn't matter what the octane is but it's a pretty specialized pump sensitive to grunge. Nev.
  4. At 100 HP for nearly 3 litres that's not necessary. IF you can air cool it's simpler to build and maintain. It doesn't look to be as lightly built as it could be.. Individual liguid cooled heads are a bit twee and a crankcase with separate cylinders lacks strength and rigidity it could have had otherwise.. People probably like it to LOOK as if it is an aeroplane motor. Some very slow revving motors are very fuel efficient.( Container ships engines) High power for a capacity is not the absolute critera we are looking for. Nev
  5. From where I sit, that explanation sums it up pretty well. There appears to be no end in sight yet either. As a well as the wasted lives, there's a companies future and reputation at stake here, and the FAA's. Nev
  6. In a similar situation, not over water but at high density altitude I took the option of a low level (very) carefully executed balanced turn staying in ground effect. Flaps would have reduced the radius of the turn had space not been available over level ground but flaps have a lift and a drag function and some simple flap designs are not very efficient at producing extra lift. It's the margin of power over drag that permits climb has always to be remembered.. Ground effect provides extra lift without drag penalty or put another way, the same lift with LESS drag.. When flying up a valley you get no opportunity to use ground effect so you need enough room to do it. That's why you don't fly up the middle of it. Not getting yourself into these situations is the best approach to flying. Nev
  7. The VW engine has had fatal flaws for years. Weak cases drive shaft weaknesses Head porting in the wrong place to name a few. These are all addressed here, but I don't like the siamesed heads, but there's little remaining of the original design (thankfully) but the "thing" would have been better to start from scratch. I recognize this is hard to do in a real sense. It's still a simple engine and if the cost is right including including operating cost it might have a future. I think the Rotax design is now all over the place. IF it's the answer the question is wrong. The 80 HP was ok at the time but still a complex installation. Too many external pipes radiators etc and too expensive for Parts. Growing the motor always has problems. A good aero motor dewsign is already on the limit or it's too heavy. Consequently the "derived " engine will have a shorter (and more interesting ) life. ALL fours have torsional vibration problems that are worse than other configurations. Flat fours have a long history in cars of broken cranks and exhaust and inlet systems are hard to get right. Nev
  8. Go back to when it worked and determine what you changed. Nev
  9. . I'm not much the wiser from anything there. . As said you can only lean an already rich mixture and also the manifold (vacuum? ie suck) is higher at low throttle openings. (not mentioned anywhere I can seeing the bumph. but it's something to take into account .I agree getting even mixtures to multiple cylinders is a difficult task from a single point "anything". "Gami" injectors did this with the common old mechanical injection systems quite satisfactorily and you don't need an auto system as it's a totally different environment it's tailored to work to with multiple and rapid throttle changes at mostly low power and lots of NO power (idle) with short periods of high power.. I question whether they are actually as trouble free as some allege. They are certainly not easy to troubleshoot when they are playing up. Nev.
  10. We are are going over old ground. Jabiru and other engines are used under a lot of varying conditions some of which are far from ideal. The engine to airframe hours thing has been explained many times. That's a case of a good deal being used against the motor's reputation. Not a true representation of reality and a bit unfair. TBO is for the major engine itself, and some claimed TBO's are fanciful. Top end work is particularly likely in little used engines or where overheating is likely due to installation or type of use. Bore corrosionand valve stem stretching etc. Steel bores not used regularly will corrode and require proper inhibiting to prevent problems affecting reliability. I know of no one doing this properly and where many planes just sit for weeks or months dangerous corrosion is likely.. I would NEVER expect a jabiru to go the full 2000 hours without head work nor would I expect any aircooled motor to do it. Some inspections can only be done properly with part of the engine dismantled. The well respect Gypsy Major generally had head work done by 500 hours. Some expensive motors have low TBO's On another note the Superior (one model (stroked crank) used in some RV's has been recalled.) that's an indication not all motors just go forever. An aero engine is not a "fit and forget" item and never will be until they are all electric. Inspect and check is the go applied as needed to any engine. No engine is absolutely reliable and the Rotax is not as reliable as it was when they were all 80 Hp and NEW. Nev
  11. P1 V1 /T1 is a constant. Universal GAS equation. IF that's a direct quote from CASA, it could have been expressed better. The latent heat of vapourisation of the fuel is probably of a greater effect than adiabatic expansion of the gas at near closed throttle. The older drip system ( metered multi point low pressure) fuel injection has a throttle body and no fuel near it and hardly ever gets ice forming in the throttle area. You can also get impact (rhyme) ice on the intake filter area, but you will be getting icing on the airframe as well at the same time.. Some carbs spray alcohol down the intakes to keep ice from forming. as distinct from water meth for power enhancement. That's for aircraft certified for flight in icing conditions which OUR planes are not.. YOUR carb ice system must have adequate heat available to do the job as designed when required though and be fully applied when used to be effective while the engine has enough heat in it to provide the heat needed to do the job. unless an independent source like electric is employed People are still crashing aeroplanes because of carb icing...Nev
  12. Opposite direction traffic is not easy to see when at the same level. IF you are relying on being seen as a means of separation without any vertical separation, It's only a matter of time before the worst happens. Nev
  13. The more who are involved, the less of the money gets to the provider. That's in no one's interests. Yes YOU should pay a reasonable amount for what YOU use Your personal info should NOT be given out without your express permission. That's a breach of trust, especially when there's a box to tick to indicate your wishes. (When it was) There's been no survey since (as far as I know). Nev
  14. On a more relevant note you find areas of high resistance when under load. ie if your starter is sluggish feel all components after a period of use and a poor connection will be warm.. Most aircraft starters have a maximum period of continuous use, then they should be given a period to cool, before further use. Nev.
  15. Conclusions based on assumptions or excessive speculations are not worth much. Some one "could have done or not done" many things but if you were not there you do not know for certain what happened unless an effective actual data recovery facility is available.. The actual judgement needs to be held back till the facts are obtained if any justice is to be maintained for individuals involved. Discussion over possible causal factors is often very useful IF valuable relevant knowledge is brought to light in the discussion process . Full investigation of incidents /accidents helps prevent similar occurrences happening into the future. That's always been the way it works with aviation and one of the reasons it's as safe as it is. Nev
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