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RFguy

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Everything posted by RFguy

  1. Just to confuse you I'd actually use 2 x 10,000uF, 40V , in parallel instead of 1 x 22,000 due to the high ripple current. But 22,000uF is what people use and the hours are relatively low for them. and I dont know about the mounting- it is highly likely the mounting for TWO would be much more difficult than for ONE. I can hear Mark saying "Glen don't complicate it ! " :-) so yeah, just 1 x 22,000uF 40V or 50V. will be fine.
  2. that cap....buy a 105degC rated capacitor.. or replace a 85degC cap every 100 hours.
  3. Right on Turbs. 100%. after the initial J170C ventral fin kit which solved the directional authority in landings, the D version went with a bigger tail , different thrust offset, and moved the engine forward a little to improve load carrying CG. Still, I think these are super and safe and forgiving airframes. Up there with best in industry. Very happy with my J230.
  4. 912 starter specification is 75 amps. Most lithium batteries are short term happy to provide 3C (3 x capacity) so a 20 to 25 amp hour battery is about the size you want minimum Regulator may need current limiting as an empty Lithium battery will drink like a thirsty horse and may overload the alternator charging circuit, Mark Kyle can elaborate I am sure on the charging. while you are there, ensure the system has a master battery isolator located adjacent to the battery. Not like the Jabiru where the full battery current goes through the firewall without fuses or
  5. I'm sure there are some fluid dynamics online model that use digital terrain models. (good ones- less so google earth as it is pretty soft (low resolution on the edges) so you can get a visual picture of your region for a specific airflow
  6. Indeed. Have been reading about what causes these eddys to detach from the surface and go off onto the plains of the western slopes, 20 nm away. The fluid dynamics are the same as the small heatsinks and printed circuit components I work on at the milli-meter scale- except that the scale is bigger ! These are actually known as 'detached eddys', and there is a critical shear velocity to make this happen- where they let go of the local surface , I never knew this definition, I generally don't run airflow in electronics cooling to those sort of conditions.... I
  7. Wow Mark, that's quite a story. Maybe my anxiety/ discomfort I felt was actual fear (from one side of my brain) PLUS the hyper-rational side of my brain also saying "airplane wont break dont worry".
  8. F10. I bet Yarram as a fairly high water content this year. I would suggest keeping it well aired. and on a pegged out tarp. and warm with an electric blanket thrown over the cowling. power I here you say ? For power, this can be done cheap... buy some removed solar panels from Gumtree, there are lots of 180 Watt etc panels pulled out, they'll sell for near free. scrap value. (current panels are 300-400W) . You can put a tech screw through the frame from underneath, just a dob of grey roof and gutter sealant (netural cure) where the panel frame mates the roof.
  9. Thanks everyone for writing their experiences. And TurbAero- well that incident over Turkey sounds like you will never forget. I can only guess there is a threshold wind speed ..... IE the production of turbulence is non linear with airspeed. Just like other aerodynamics, IE the turbulence gets 'detached' from the area of the rough surfaces and continues. Some reading required to understand the precise mechanics and airspeed-severity curves and statistics. I am familiar with mountain turbulence, living in Canberra and Denver .. it is a regular feature from t
  10. Now, that NARVA unit you mention, Narva stuff is OK, but there is little quality control and variable manufacturers. Consider you want to be able to cut the battery very close to the battery. A hand mounted switch might not permit a suitable mounting location. All GA aircraft I've looked at have a contactor (relay) near as damn to the battery. I have bought a high ambient temperature , vibration rated and 250A rated , contactor, with screw bolt terminals. for my Jab to install...was about $40-60 I think. The ones (isolation contactors) I see in most
  11. In times when you might need a twin, give me a single reliable engine and careful operator and airframe parachute over a twin....
  12. It is WHY aircraft users should use Lithium Phosphate batteries ( LiFePO4 ) Not "Lithium Ion" (various chemistries- cobalt polymers etc) . You don't get runaway meltdowns like classic "Lithium Ion". There is an energy density penalty with LiFePO4, about 25%, but you get safety. Nearly unconditional stability.
  13. Bit of a story here.... Well today, at Cowra, YCWR I did my morning exercises as prescribed by my instructor, EPs, one overhead. Got the hang the descent rate of that aircraft, now. not much wind to speak of. practicing my coordination in figure-8s Then. Then after doing some other stuff, coffee, decided to just go for a leisurely fly @ 96K CAS (16lph), instead of 115K CAS (26 lph) . Have a look around. loiter at 2000 AGL... Went down south, around a bit, very nice, then headed back north and a 35 kts headwind came up. Not to worry, no hurry. Back North for 20 mi
  14. Jab flaps control location : I actually want to move (or add a 2nd ) my flaps control of my Jab from down there cluttered between carb heat, choke and cabin heat , between other controls to the spare area right next and above the throttle. That way I could keep my hand on the throttle and drive the flaps in the same hand instead of having to reach over with my throttle hand, reach long and lean over and stretch, and look down where my hand is , when I should be looking outside the plane during a rather critical manouver in a late go around..... ideally, first s
  15. nose up ? I dont think so if you are onto the stick like a tiger and arrest it if it tries to... application of a full power step I would think would be more likely to provoke that. I would think those flaps would normally move centre of lift aft slightly. nose over a bit , but then the airflow over the elevator changes, also. It looked like a stall to me because at the initial nose up, it looked like poor roll control -IE stalled outer wings .... (or suboptimal pilot technique), only looked at it once..
  16. I think the Old Bar ferris wheel was a diferent category, cause etc. It might have been recoverable (after the in-ground effect stall ) if the stick had been let come back to neutral at WOT. . maybe a bit of stick forward , as required, to counter any nose up tendency with the flaps out.....ie a in ugly transition from a power-on stall back into level flight inches above the runway. maybe. it depends just how much the speed decayed in the stall. There was a panic and stick held back in panic I guess. Pilot learned basic instincts (stick forward) did not prevail.
  17. Hmm good quality balustrade ! It didn't look windy. Pulled on too much pitch too early, stalled, did not stick forward, but then applied WOT but didn't release pitch ? so the plane flying OOC in a power on stall, more like was looking like a STOL contest ? Where is his instructor ? Fortunately we don't see too much that is this bad. I get annoyed when I see this because it doesn't do anything for us in the public's eyes.
  18. D=A-B-C ?? really ? What are the domains of A, B , C ? surely not unbounded ? Not D = (a-a^2)*(b-b^2) + C ? surely the result is quadratic ?
  19. These swivel ball ends live outside, and as do the slides. IE like elevator control on the jab, ball end exposed. I cannot find anything specific on lubrication. Indeed, anything sticky would attract and hold dust and dirt- completely unwanted ! Which leaves dry or self lubricants only as options, if indeed they are really required (or not) Graphite powder ? Or just leave them ? They have a long life by all accounts. Do the swivels use a self lubing nylon etc internally? same question I guess on the Rod End wiper seals ? -glen '
  20. yes You need to overhaul the gearbox/ clutch more often (see service letter) Oil changes are recommended every 25 hours instead of 50 hours (see service letter) You are likely to get CC buildup (since Bings generally run rich of peak ) There are additives like Decalin Runup that reduce/eliminate CC buildup. I use that on my Jab with LL100. I don't know about about the gearbox though and whether there is an additive that can reduce that problem- - the combustion products of the lead end up in the oil and the gearbox accumulates it.
  21. RFguy

    Gazelle RPM

    yeah certainly too heavy. as previously discussed in rotax factory letters, 5200 min static. engine has excessive load and labours. you'll get improved everything with the higher static rpm Our club Brumby was propped for 5200 and fell to 4850 gradually as the propellor aged and became pitted (1800 hours I think now) . We recently re pitched it half a degree to restore the static RPM of 5200 . Despite the prop damage, repitching for 5200 again was like getting a extra 10 HP in flight and TO https://legacy.rotaxowner.com/si_tb_info/serviceletter/sl-912-016.pdf
  22. Paul at OAT of 9C, at sustanied level flying at 25lph ish, I have a temp rise of 49 deg C. IE 58C Not enough ! I have been experimenting with gradually more air damming in front of the cooler. for warm up, I 100% block it, but it only gets to about 60 deg C at OAT = 10C. even after cylinders have got to 120s...
  23. RFguy

    Gazelle RPM

    What static RPM do you have at start of TO roll , nil wind ?
  24. Comprehensive Rob !. Only comment is that you might have over-capitalized on the panel avionics for what some operators may want.
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