IBob
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Everything posted by IBob
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I recommend downloading the Rotax Line and Heavy Maintenance manuals: they're free. It tells you how to do an oil change, including important details like DONT turn over the engine once you have begun to empty the oil out. The idea is to keep the lifters flooded and so avoid getting air in them.............
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sfGnome, there is a permanently open rearward-cowled vent in the roof of the luggage area. The doors are a 3 dimensional work of art but not entirely rigid, so do not neatly seal all round (though this could probably be addressed with different thicknesses of draught stop. The doors have round ventilators that can be closed. The firewall can be closed off using boots on the control rods. The remaining major source of draught would be from the rear fuselage, through the various openings around the controls, seat pans, luggage area etc. I expect these could be reduced. The fact remains that you don't need much gap in an aircraft to be very draughty: the coldest flight I have ever made was as pax in a Piper Seneca mail plane, midwinter: the seals round the doors were a bit tired, the resulting draught was strong and constant.
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Still clinging to stale old ideas of manhood, Flightrite???
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Some sort of Dzus fastener? Search Dzus on Aircraft Spruce.
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Aircraft into power line 26/06/2022
IBob replied to tillmanr's topic in Aircraft Incidents and Accidents
And yet more off topic: I was part of a job on Paramushir, a Russian island off the Kamchatka peninsula. We were there midwinter, power on the island was from huge ships engines driving generators in a building out back of town, we were commissioning a fish processing plant on the coast out the front of town: an experience I'm really glad I had, but that I wouldn't choose to repeat. The power made it's way from them to us via aluminium cables on wooden poles with wooden crosstrees. It snowed and blew a great deal, the wind driven snow would build on the upwind side of the poles, the power would then track down the pole, and eventually incinerate it. As we went to work each morning we would count the missing/burnt pole stumps, with the crosstrees still holding the wires apart, but sagged right down near the snow covered ground........ -
It is a wonderful resource, extralite..........would be even better if more folk actively shared their experiences here. We all get to benefit and learn.......)
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Hi Garry, and welcome. Can't comment on the Classic/VG heater, I believe the muffler setup is quite different than the XL/S. But I can tell you that the heater in my S is pretty useless too, though how much that is the heater, and how much general draughtiness from various places, I'm less sure....
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https://www.theguardian.com/commentisfree/2022/jul/18/what-can-smug-australians-teach-the-uk-about-surviving-a-heatwave
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Hi David, did you manage to isolate the problem? Interested to know what you may have found.......
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AVWeb discussion: the Dale Snodgrass gust-lock accident.
IBob replied to Garfly's topic in Aircraft Incidents and Accidents
As a relatively low hours rec pilot, I have found that I have to guard against two things: 1. An interrupted preflight, or one that deviated in some way from my normal routine, allowing missed steps loss of focus and oversights. 2. Allowing the preflight routine to become 'just' a routine, rather than actually focusing on each check: I saw this begin to creep in with my engine instrument checks, where I wasn't actually focusing on each one to verify the reading before moving on to the next: a subform of get-there-itis. I have tried to break that habit by placing my finger on each instrument as I check it, which slows me down enough to do the job properly. I also notice when watching YouTube topdressing footage that the pilots 'stir the pot' with the control column prior to every single takeoff. Presumably this is due to a history of controls damage or failure in the industry, but if it's good enough for them and in view of the above, I need to make it good enough for me....... -
Hi Glen, I can only speak from the experience of my own build: 1. The engine was much easier to fit to the ringmount supplied, by first removing the coolant pump cover with it's coolant outlets. 2. After fitting the engine to the mount, the pump cover was easily refitted, but the position of two of the coolant outlets had to be adjusted to allow the hoses to pass through the ringmount. 3. This was done by holding the cover gently in vice softjaws, gently heating the required outlet and rotating it by pushing on a piece of dowel inserted in the outlet. I made these adjustments several times before getting them right, and was concerned that I may have leakage as a result, but there has been no problem. The pump outlets are a soft alloy with a fine thread secured with Loctite 243, which requires a moderate amount of heat. (The coolant inlets at the cylinder heads are a similar fitting with the same fine thread, but a higher temperature Loctite is used there, requiring considerable heat for removal. I have replaced one cylinder head port, it was a difficult job which took me three attempts to achieve a leak-proof installation.)
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Suggestion: Before installing engine, remove rear engine cover and check ignition coil and trigger gaps are set correctly. This is best done with non-ferrous feeler gauges (some sets include a selection of brass gauges) as the rotor magnets will stick to steel gauges, causing the gap to feel snug even when it is not. In the absence of non-ferrous gauges, ensure the next size up is no-go. This is generally easier to check with the engine out. These coils provide both the power and the trigger for the ignition, and correct setting is critical to good starting. We have seen one instance of incorrect large gaps on an older engine causing poor starting, with resultant expensive clutch damage.
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There are a couple of threaded holes in the top of the engine, approx 150mm back from the gearbox. A fellow builder lent me bolts with the bracket he made to go on there. The lift here is on that bracket on the shackles you can see. The strop is on there just in case, and under no load. You can see one of the holes in the second pic.
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I think you've picked it about right, Jim. Regarding the minimum cruise speed, there is a general sense that the Rotax is best run at 5000RPM and above, so a combination of that and prop pitch (which is a compromise between takeoff and cruise performance) will tend to define your minimum cruise speed. Or that has been my experience.
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Diaphragms and cuffs replaced before or after problem emerged? And when you said runs rough after takeoff, can you be more specific? Is this when you throttle back to cruise? And if so, how does it run on all other modes of flight and idle etc?
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Have you weighed the carb floats as per the Rotax spec? Rotax seem to have gone through an astonishing number of float versions, possibly one of yours is marginal (though I would have expected that to show up at low power settings). It certainly sounds like a fuel problem, have the carb rubbers and seals been replaced?
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The history question: Have you owned and flown the aircraft for a while? If so: Has it always done this or did it just start to do this recently? If it started recently, was it a slowly deterioration, or did it just suddenly start to happen? And, most important: What, if anything, was done by way of maintenance or adjustments in the the engine bay before or around the time that this began to occur? Also: Were the fuel filters changed at the same time as the rubber replacement? And are you seeing good (2psi+) fuel pressure at all times? (But bearing in mind that the current Savannah fuel filter arrangement has one filter before the electric pump, but 2 filters to the respective carbs, which are after the fuel pressure reading is taken.)
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Hi Jim, I can't speak for the tailwheel version, but my tricycle S gets about 86kts (99mph) at 5000RPM. This is with a Bolly 70" prop pitched to give a good compromise between STOL performance and cruise. The Savannah will certainly go faster, but like most STOL designs it has a fair bit of drag, so power requirement and fuel consumption rises exponentially above this speed: at 86kts it feels to be cruising easily. This is with a 912 ULS. I believe Dan Tonner's VG XL (above) is a 912UL? You may like to visit John Gilpin's Stolspeed website: he has done a great deal of work with VGs different props etc on his Savannah VG: https://www.stolspeed.com/
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What is the history, David?
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By varying the pressure in the float bowls: The bing carb has a vent line, intended to keep float bowl pressure the same as incoming air pressure (so, for instance, where there is an airbox, the vent lines are plumbed to the airbox downstream of the air filter). Downstream from the carbs is a narrow equaliser line between the two inlet manifolds. A bit of vacuum is taken from here (via a needle valve) mixed with ambient air pressure, and fed to the carb bowl vents, so reducing float bowl pressure. Or that is how the less costly off the shelf setups seem to work. They're a bit mickey mouse in that any change to the throttle setting immediately upsets the setting of the leaning mechanism. So the drill when changing throttle setting is first go full rich/ then adjust throttle/ then readjust leaning. That's as I recall, if I've got it wrong I'm happy to be corrected.
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Chups? Is this fush and chups or potato chups??
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In fact, I see Mark acknowledges that in his initial post on this thread. So I'll leave it there.......
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Wukfit, for the record, I'm sure Mark would be the first to acknowledge that this was a Kiwi innovation. What Mark has done is sorted out a very nicely engineered version for the benefit of those needing it.
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I was in Germany when the NSU RO80 was introduced. It was a beautifully engineered car, futuristic for it's time. Part of the promotion was the claim that the faster the thing went, the more economical it became, a concept that new owners embraced with relish, there being no speed limits on the autobahns. They sold well initially, but not so much thereafter. NSU nearly went broke trying to maintain them, and owners took to holding up 1, 2 or 3 fingers as they passed each other, to indicate how many times they had had the tip seals replaced under warranty......
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Markdun, I would suggest it is a matter of horses for courses, as they say: depends on the configuration of the fuel system and the pilot's understanding of that. So I have no opinion as to whether it is a good idea in your aircraft. In my own, it is a nice feature, allowing outboard tanks (which have no sight glasses) to be flown to exhaustion: they are less used than the inboard tanks, and would otherwise have stale fuel sloshing round in them. I n addition, I and others have written here about the benefits of having a 6L receiver tank between the main tanks and the engine: having a low level (its actually a not-high-level) indicator in that tank is the icing on the cake, giving assurance that we have the full benefit of the time that 6L buys.
