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About jetboy

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    Omaha Flats Airfield
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  1. jetboy

    BFR in my CH701

    Mine gets better climb rate and engine cooling with flap set. I use 50kts and a climb prop running at 3200 - 3300 rpm. strut fairings made a big difference to climb rate too. yes nothing can fix a hot day with full load, in that situation I plan on a climb rate around 200 - 300 fpm, its not pleasant and even a Rotax 2 stroke would probably do better. Ralph
  2. jetboy

    Radio replacement

    I've often suggested a look at the Flightline 760 (ACS) as it seems to have similar features to Microair or Xcom at a lower price point. There are few of them about so quality is unknown - the first one I've seen was in an aircraft last week and they had no issues with it. Trig has a good record here. Ralph
  3. jetboy

    701 elevator / flaperon control system

    The standard setup has to be rigged with enough slack in the elevator cables to allow full right aileron deflection and then the left deflection makes the cables loose. I think the rigging instructions are deliberately vague because the simple to construct design has these issues. Another not obvious rigging situation is the rudder tensions, which need setting with the nose unloaded because the cables go slack with nose strut compression. Incidentally my initial CAA inspector was puzzled with the tightness of the cables and thought it might be due to the plane being rigged in the Czech winter and now its summer in NZ and aluminium fuse has expanded....I still laugh about this. Rather than second - guess the design I just call it a backup feature that holds the rudder firmly on - anyone familiar with 701 Hstab and rudder attachments will know I'm serious about this. If you are at the fabrication stage I'd do the mod to not have the elevator yoke rotating on an offset to the aileron tube. I've been flying mine since 2004 and the remedy to reduce the aileron bias (to the left) was to alter the position and tension of the bungee inside rear fuselage so it pulls the upper cable to the right. this by no means cures the problem just makes flying less tiresome - it holds a bit of trim tension the way that centralises the stick. Ralph
  4. I'm a bit confused about the "Jabiru return system". Apart from mate with SK who would empty the catch container to the sump as part of preflight checks. If done with a designed oil seperator, theres probably nothing bad about a return system, did Camit offer one? My 2200 would fill 500ml catch bottle about every 15 hours. A bit less often now with new rings @ 500 hrs. I have the original dipstick before Jab "fixed" the issue of blowby by shifting the full and empty marks down about 1/2" I'd rather keep the level up at least the underbelly of my plane is corrosion treated daily. I just had another pail of oil delivered, 19L cost $299. Maybe I should reconsider.
  5. jetboy

    Headset upgrade

    a long time ago I bought Headsets inc. (link in Downunder post) ANR kits and fitted them to my existing headset. They work well and still in use, but I run them on aircraft power rather than 9V battery
  6. jetboy

    Engine Exhausting

    For a well known brand its normal. "exhaust valve opens 65 deg BBC." For a Jabiru, probably not. they usually leak throughout.
  7. jetboy

    Vacuum Gauge

    I put one on my 2200 to measure the prop load vs rpm temporarily. You just remove a small screw from the middle of a port on the carb underside and place the hose there. It doesnt matter what type of gauge you use if you convert the units of scale. I just borrowed a gauge from a set of 4 carb balancing ones from a m/cycle supplier, these come with a damping valve fitted so you can remove the chatter, depending on what you are trying to use it for. they are compound gauges, not sure why for m/cycle tuning because bikes dont usually have turbos. Bought the gauges because the cars i was working on needed 4 carbs balanced - Honda S600 & H1300 Coupe
  8. jetboy

    Iridium plugs

    Bruce, If you are looking at mixture issues and the behaviour of EGT at full power, a lot of this has been covered by various Jab servvice letters, Jabbachat and finally the "manuals" My engine was a few hundred prior to the 'economy running kit' which after about 5 reissues became the production carb jetting setup today. Note that it only applies to the correct type of prop loading conditions. I spent lots of time swapping / redrilling jets as starting with OEM kit #1 it needed constant updating by factory SB. In the end I got the correct response which is a higher EGT at cruise power 2900 - 3100 rpm and a reduction of EGT from 3100 - 3300 rpm. This is very similar to the behaviour of the MS carb / O-200 my C150 had. Other than prop loading, there are a couple of things that might affect your response. The way the carb float vent line is vented (must be into the air intake after the air filter) Some jab engines were / are supplied with larger float valve seat diameter. There are different float valve spring tensions available There is different fuel pump spring tensions there is different fuel pump plunger lengths They changed the cam profiles they retarded the timing on 3300's
  9. jetboy

    Iridium plugs

    My engine (2003) and those up to about 2010 came with red HT leads which are plastic core carbon type. To be fair, the old automotive carbon leads were much less reliable than Jabs (leads) as the core seemed to be cotton wrapped carbon which would crumble out. Jabiru switched to the black leads which are believed to be inductive wire type - I havent had the opportunity to test them. I use the Bosch ferrite core helical wire inductive leads from SCA. The wire is SS and has a resistance proprtional to length but generally less than the original carbon plastic core Jab OEM red ones. Cars use these leads together with R spark plugs, but that cant be compared to the Jab setup which uses lawnmower parts mixed with a car distributor (variable spark gap right there) so I tested the voltages and spark with different leads, plugs and gaps first. If you wanted low resistance you can buy Magnecore or similar. care needs to be taken if reterminating these leads, different plug caps use diferent ways to spike the conductor. I dont know what these quotes about silicon leads are all about. Silicone leads refers to the outer insulation covering, nothing to do with the conductor.
  10. jetboy

    Iridium plugs

    Pity NGK dont make their shielded plugs BS-6E and BPS-6E in 12mm. Aircraft shielded leads are constructed with a helical wound wire core which is good RF supression without the carbon which hasnt been used in cars for 30 years and Jabirus for the last 10 or so....
  11. jetboy

    Iridium plugs

    I have been on R plugs in my 2200 for 12 yrs - ever since replacing the original resistor carbon leads with the inductor type. This was done to reduce the radio interference that Jabs are so well known for. Extensive testing with lab equipment showed no change to the loading or stress on the coil packs or any other part of the system. The coils are for Honda lawnmower engines and have a resistor plug or resistor integrated cap depending on market. I never clean the plugs, just replace at 200 hrs. They are gapped to the Jab setting as these are standard plugs. This would more than make up for the perceived effect of the resistor. In reality the resistor doesnt lower any voltage to the electrode because there is no current flowing at the time - see scsirob post If I were to fit Iridium, I would leave the gap at the wider setting its because the spark threshold voltage is lower to break across a pointy end. Next plug change I might get Iridium, but the cost benefit is not great if I'm getting 200hrs on regular plugs
  12. jetboy

    shark fin antenna

    Pilot dentist buddy X-Rayed one. What you see is the film taped to a window, hanging in the conventional way. The guts of the thing appear to be the connector centre shaft coming down, soldered to a flat perforated pice of metal, roughly the shape of the outer moulding. Radio is a black art, what we see doesnt allways look plausible. GPS patch antennae are another mystery.
  13. jetboy

    shark fin antenna

    this is what the dentist saw
  14. jetboy

    shark fin antenna

    No, they are more robust and expensive. The cheapest version of stick and ball are prone to breaking when washing the plane.
  15. jetboy

    Which Engine???

    only new (gen4) for the Jabiru, but postpone this decision until there is an established track record. you could safely choose a timex 912 and just overhaul the gearbox, they have a good record and flight schools often renew them rather than overhaul. the D-motor is my personal 1st choice, it comes down to price and that depends on the country. In my case, the existing engine mounts are for Jabiru / D-motor / ULpower and that represents a big difference. The ring mount for the 912 is pricey but essential and adds to the cost.