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IBob

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Everything posted by IBob

  1. A significant number of builds report the same problem: fuel pressure shows okay on the ground, but appears to diminish with altitude. There is generally nothing wrong with either the gauge or the fuel pressure. The problem is that the gauge needs a static port, so that air pressure inside the gauge is able to change with changes in altitude. The top of the gauge body, behind the panel, has a little rubber bung in it, and the quick fix is to just pop this out. A better fix would be to then install some sort of filter in it's place, to prevent the ingress of dust & bugs.
  2. Our jump club, about 20 people, managed to get a session in the Airforce (de) pressure chamber in Auckland years ago. They took us all to 18,000ft, had us take off our masks, and the result was very pleasant, like being tipsy. Everyone was happy but lots of us couldn't now recall details from the simple briefing we had previously attended. They then took us to 25,000ft and had us remove our masks, 2 at a time, while the rest of the group watched. The unmasked had to do simple repetitive subtractions (300 minus 7, minus 7 again etc), with regular physical checks that involved pausing the calculations and repeatedly touching their own nose then touching a finger held up in front of them (we had a couple of instructors in there with us). Most had trouble physically locating their own nose, and then accurately touching the finger. One got target fixation, insisted on continuing with this exercise and holding the instructor's wrist when he tried to take his finger away. For the most part we were told to put masks back on as our performance worsened after about 2 minutes of this. A couple didn't want to do this despite repeated commands (we all had on headsets), had to have their masks forcibly applied. And on the way back down, while the recovery is very rapid for most (with a sudden return of colour vision we hadn't noticed had faded) one continued into hypoxia, requiring oxygen and a lie down. There was also one, and a smoker at that, who had no trouble with the required exercises at 25,000ft and after a full 5 minutes was apparently entirely functional. What came out of this for me is that our bodies generate absolutely no warning signs as hypoxia sets in...if anything, there is a sense that it's all going wonderfully well. So if in doubt, trim for descent (I believe that's right, but stand to be corrected). And different people can be affected quite differently.
  3. Continuing to follow (and enjoy) your Sonex voyage of discoveries here, Skippy. It continues to raise interesting stuff I'd never thought about. I know where there's as Sonex parked at the back of a hangar...it almost makes me want to look at tinkering...........)
  4. What Nev says feels right: stiffen it up and you increase the loads elsewhere. My first thought was to try and limit movement with smooth running, including starts and stops, hence the the question about prop weight which seems to make a big difference in that respect.
  5. FWIW: My idle jet and idle throttle stop settings are as per the Rotax manual. (I checked them at new and one of them was a bit out from the factory, can't remember which one but it's a very quick setup, and evidently worth doing). With those settings, the tacho drops towards 1400 when pulled to the stop, and I switch off the ignitions almost simultaneously as it is getting there.
  6. Skippy, what weight of prop do you have? And what are your engine starts and stops like? I ask because I have a reasonably light Bolly 70" prop, and that coupled with the improved Rotax ignition retard, plus a bit of practise and understanding gives me very smoothe starts and stops. Our club Tecnams, however, have the much heavier prop mandated by the manufacturer and engine start/stops can be quite ugly, no doubt resulting in considerable engine movement.
  7. FWIW kbstone, my kit came with the skin holes and blowout panels for a parachute setup. Since I have no parachute, rather than mess around with those panels (which go under the skin), I just blanked the holes off with a simple capping panel. This I made with an offcut from the kit, specifically the cut out piece in the lower wing skins where the tanks go in. If someone wants to fit a parachute in future, that is simple enough. In the meantime it is a tidy and weatherproof solution in a place nobody ever looks anyway.
  8. I don't know kbstone. What the kits have now is a round pattern of drilled holes in the top skin, that fit under the cover you have there. I would add a skin over that big hole, with a circular pattern of round holes, then mount your cover over that. We put the cover on late, as we like to apply silicone between skin and cover, also a lip of silicone round the holes to keep out rain both in the air and on the ground.
  9. Pat, what I meant by 'the arrangement' is the individual air filters on the carbs, taking air always from under the cowl, which should be warmer than outside air. And my suggestion about sustained low power settings (usually on long descents) was because the engine will be producing much less heat in that mode of flight, so the air under the cowl and entering the carbs will be cooler. I cannot say if your engine compartment is warm enough to avoid ice. That depends very much on how the air circulates there. I suggest your best source of information would be from pilots operating similar aircraft in your climate.
  10. Yep, that's the arrangement on at least one of our club Tecnams, and I'm not aware that they have icing problems, apart from one possible incident some years ago. How effective it is will depend on what sort of temperatures you get at the air intakes under the cowl. Probably best to avoid long descents at low power settings?
  11. Yes, absolutely, carb ice can be a problem. Some Rotax equipped aircraft do not have carb heat, but instead take air from under the cowls all the time. A VG on our airfield does have carb heat, and the XL and S Savannahs all do too. It's probably easiest to post a pic of what you have under the cowl, Pat?
  12. Strictly speaking, that aint a float bowl vent....it's not for venting, it's for pressure balancing in the float bowl....but I'm sure we've had this conversation already........)
  13. Skippy, I can see the problem right there: someone has made off with your front wheel.......(
  14. I have the later model ULS with the CH coolant temp readouts for cylinders 2 and 3. 2 always reads cooler than 3. But given that 2 is front LH, with the sensor at the front of the head, while 3 is rear RH, with the sensor at the rear of the head, that has never surprised me, and since they are both well below max temp, it has never bothered me.
  15. True. It was instructive flying without the gauges, not that we were up for long. And I spent the rest of the afternoon purging the static pipework, disconnected, with a hot air gun.
  16. Either side of the rear fuselage, Nev. And I only once washed her with a hose.......and after that I modified the static pipework to add a high spot before running it forward.
  17. My kit supplied pitot is simple aluminium tube, not sure of size, maybe 4mm ID. Cut off square, but with the inner edge of the cut bevelled, so the tip is a sort of little funnel.
  18. RFguy can you suggest where to source headphone jacks? Are we best to go to aviation outlets, or is the quality similar regardless? Thanks.
  19. Does the M760 have VOX mode? Is that not intercom? I'm no expert on this but others here will know. Maybe consider putting the jacks in baggage front centre roof as per the South Africans: they are practical outfit, much of what they do makes sense.
  20. Hi Marty, depends on the radio. Mine is XCom, which has the intercom built into it, so no additional gear required. I would think most radios now have that for a simple 2 person setup. As for position of the jacks, I had them on the floor console forward of the stick, but didn't like that, so have now shifted them to a small box at the backrest between the 2 seats. I prefer this as I can see them in case I need to check plug seating in flight, and the cables are inboard of both pilot and pax, so we're not dodging round them when getting in and out. The only complication we then had was getting the headsets crossed up with someone else as PIC, the problem then is that you don't realise you are not transmitting (since you are pressing the wrong PTT button). it.that. I saw recently where the South Africans are putting their jacks at centre front of the baggage area, which is another possibility. A lot of Savannahs have them mounted at the front outer corners of the baggage shelf, but I'm told that can be very difficult to reach or see if you need to check plug seating in flight.
  21. Yes, good luck with your search, Oskar! I had not meant to discourage you, only to say look carefully before you buy. The Savannah is a very good aircraft of it's type, versatile and fun to fly. There are now thousands in use around the world, including a large number in Australia, and a smaller but growing number here in New Zealand. May one of them find it's way to you!
  22. It can be, Oskar. Savannah supply a primer paint that is used at all lap and metal joints. If applied with reasonable care on both surfaces, this should protect against occasional moisture. But any paint system has it's limits, and if moisture and contamination are constantly present...as they can be at lap joints in constantly wet situations...then corrosion may result. It may be worth getting maintenance people to show you what corrosion on aluminium looks like: typically, once it reaches the metal, it then runs under the good paint, gradually spreading.
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