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jcamp

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Posts posted by jcamp

  1. Interesting project, looking at something similar

     

    Couple of points on the circuit:

     

    Power Supply:

     

    LM78xx normally have 35v max. This can be problematic with a voltage surge on shutdown, would be inclined to make the cap say 63v and stick a 20v zener in there.

     

    Op amps

     

    A DC gain of 273 might be stretching it, I would be inclined to use an instrumentation amp in there to avoid hassles like device selection. Probably doesn't really matter what, IIRC last time there were some INA 118's floating around and they worked OK.

     

    (Not an electronic engineer but employ some.)

     

    Also may have to go to shielded stuff on the thermocouple wire if there are too many problems with a noisy environment.

     

     

  2. Tubing can cease to be tubing due to magnetic field in a lighting strike. One of the missing photos from the UK shows tube in the aileron control which has been crushed by this.

     

    Read the bit on P5 where it describes the state of what had been a 16mm OD, 1mm wall thickness tube.

     

     

  3. Stall behaviour is affected considerably by power and a full power/flap stall is quite different from a power off one.

     

    A couple of months after I got the J160, I was flying on a day when the air was calm enough to do a meanful check of the book figures for stall/IAS. All was OK even allowing for some bird sxxt on the left wing until fullpower/flap. The angle was pretty extreme (and I don't really see how you could get into it unintentionally) but the break was sharp and I turned through 90 before recovery.

     

    Figured I had better brush up on spins before repeating the exercise so did a session in an Aerobat (flying from the LHS for control similarity).

     

     

    • Caution 1
  4. done some stalls the other day in the J160-C and the problem is this ..... it does not stall 011_clap.gif.c796ec930025ef6b94efb6b089d30b16.gif you just start loosing height at a slowish decent and thats it...35 Kts and the elevator and rudder still have authority..... but not a recomended thing for 3Ft AGL

    Check you are OK on spins and go to 4,000 AGL then try the goround configuration - full flap full power.

     

     

  5. The VANS factory told me that they could see no reason why a Jabiru 120HP engine would not be a reasonable replacement for the Lycoming 0-235, especially interesting as they are 35kgs lighter. You'd need longer mounts and cowls, but that would be unlikely to exceed the 35 kgs saved.

    The longer mount and cowls could be a big problem aerodynamically as the history of turbine conversions of piston engined trainers shows.

     

    More area up front needs bigger fin, needs structural changes to the rear fuselage etc.

     

     

  6. "No doubt Jabiru would not be included as there is little chance of damage being caused by underwing numbers

    The J160C has the underwing markings as outline only. I presume this is to minimise thermal effects from radiant energy from tarmac etc.

     

     

  7. Some legalities from CAAP 234 (1)1 Assume private/piston Variable reserve not required; 45min fixed reserve required.

     

    For a real flight and not an exam practical considerations revolve around the wind and where did it (the figures) come from. Remember although low at 2000ft they are 25% of IAS.

     

    If the winds are forecast as stated for the next 12 hrs AND confirmed as actual then maybe use a 20kt headwind. So assume only the first leg can be done.

     

     

  8. Its the same senario of banks having to increase interest rates above the reserve bank rate because their borrowing costs have increased, when in act the interest rates in the US are at record lows ( which is where we are borrowing the money from)

    The Fed rate is only for the US banks in an attempt to disguise their insolvency. The real rates if you borrowing are much higher - IF any money is available eg NY Port Authority paying 20% after no one bid at a loan auction.

     

     

  9. How much paper could you need for the plain language. I just got the area forecasts for a flight I do frequently (Melbourne to Caloundra), came to 29 pages and chopping out irrelevant airfields cut it back to 20 pages - a bit more than normal which would be in the 15 page range.

     

    Thats bad enough but an extra 30 pages of waffle would be worse.

     

     

  10. This all sounds like the what my wife's (then 38) instructor said when she finished her nav stuff and was filling out the form "You have the hrs and as I don't think you will be buzzing houses or chasing cars, I will also put in the passenger endorsement". Should he have also said stuff about shutting down engines and aeros"

     

     

  11. Had problems with getting the phillips screws in the spats out and then back in tight enough. Solved that by using hex socket head screws. They don't appear to be available in Aus or anywhere at 100 degree but Fastener Express in the US has 8x32 Flat Head Socket Cap stainless screws available in 82 degrees.

     

     

  12. Flight over builtup area in experimental a/c is the same for RAA and VH. CASA or approved person see CAR262. Asking a couple of years ago there were requirements:

     

    Engine - 912 or Jab, also certified lycosaurus etc OK. Single ignition no.

     

    Aircraft - Savannah or Jab OK. (and presumably others)

     

    Would want to see more than minimum hours flown off.

     

    The rest appears to be a grey area on both the aircraft and engine ie your Brentc MK1 superbird might require quite a bit of engineering and flighttest data as would the dual ignition WRX motor. It's basically a matter of convincing cynical engineers.

     

     

  13. some things to also consider. an 45amp alt under full output will take around 4 to 5 hp from an engine.

    ozzie

    Boring engineering stuff:

     

    45 amp x 12V= 540 Watt = 540/746 = 0.72 hp

     

    not so bad for 28V at 1.69 hp but there is still some SERIOUS problems with drive/alternator/regulator/measurement there.

     

     

  14. EFATO before 500 ft

     

    Plane has failed you - write off

     

    Nose down - keep airspeed

     

    What you see in the windscreen is what you have

     

    Pick the least worst option for you, maybe fly between trees not stall on top.

     

    Fly to the last

     

    Mentally think and plan NOW - when it happens you just have to put the plan into action, no time to debate. Those who have done CONTACT or AMBUSH drills will know the reasoning.

     

    Personally 200 ft EFATO

     

    120 ft partial EFATO

     

     

  15. A further point on instrument "quality" (interface design, useability or whatever buzzword is appropriate). The moving map GPS is a pretty common instrument and theoretically can provide direction but its slow response and reversal when the map orientation is changed is not ideal. In a situation of VFR but no horizon I found I got disorientated probably within a minute. It was more difficult than the magnetic compass (flying north at the time).

     

     

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