Modest Pilot
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Everything posted by Modest Pilot
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One of the things worth considering when buying headsets is the ir weight. This was pointed out to me by the Van's factory pilot during a demo ride in an RV6. I went for the Peltor 7000 they used for this reason. They give 24 db passive protection and you can actually wear then for longer 5+ hour flights.
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Jabirus have a NACA 4412 non laminar flow airfoil and V G's are unlikely to improve this type of wing section. We were presented with a set to try on a J250 on a no cost trial basis, we sent them back as useless. (placing them on the underside of the elevator did give a tiny increase in up control force) Putting anything on one wing only for testing is probably a good way of killing yourself! A good book on the subject called Airfoils by Harry Riblet is available from EAA for $18.
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Re:B747, not true, but like most swept wing aircraft any rudder induces yaw instantly triying to roll the aircraft; shows up as displaced aileron. Similar but much smaller effect in Jabs.
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Hopefully a picture will appear in my profile
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I got approval to build proper 3.7:1 teardrop spats as per "Hoerner" instead of the Jabs mudguards. Worth 3-4 knots. Performance now with a Sensnich 60x56 prop at 600kg: Max Speed: 140kn @3100rpm 2800rpm 1000ft 19lt/hr 121kn Egt 690c A bonus was that you can exactly trim the rudder for zero yaw on the Dynon. (but only a for one rpm eg:2800rpm) by slotting the attachment holes on the front spat. Result no more out of balance fuel.
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I looked over the Sling D6 at Oshkosh 09. This looks like a very well designed and put together aircraft. Features such as two piece canopy, closed bulkhead behind the cockpit and balanced controls look good. The next leg to Honolulu could be a challedge, they are right on minimum fuel and the winds on this run are rather fickle. It's weight and speed range would be just about right for a 6 cylinder Jab with a fixed prop and you could probablly get it in the air for around $45,000.
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One thing not mention was the I A S when this occurred. At low airspeeds it can take a suprising amount of elevator to effect a recovery of attitude. This has trapped a number of pilots from Chipmonk to airliners pilots. Are you sure you had full forward control stick?
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I used a K&N filter on my Nissan Patrol for over ten years, great filter for places like Frasier Is. (lots of sand) The downside is thatwill you find over the years that the oil from the filter does leak into the inlet manifold. It bakes on into a glazed brown-yellow substance and is devilish hard to remove. Re-oiling is also a rather messy business.
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Pilots without transponders....... scary stuff
Modest Pilot replied to a topic in AUS/NZ General Discussion
I presume you are thinking of TCAS. Unfortunately this system is far from perfect. Despite it being mandated to work in three dimensions long ago by the U S congress, it still only gives pull up/push down avoidance. It is often confused by high rates of desent or climb for starters sometimes giving exactly the wrong instructions, I've lodged around a dozen Incident Reports myself in this area. All false warnings require this report; The ATSB must have hundreds in there files, they just acknowledge and appear to take no action so I guess they are swamped. Keep up those radio calls! -
Well you might be lucky on Frasier Island. Came over the sand hills from Lake Allom just North of the wreck and there was a F111 heading South just on the breaker line. I could see into the cockpit so they must have been under 50'. Wings back and going like the clappers and kicking up water spray behind. Looked like they were having a ball!!!
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The coke is actually not a choke at all it's a start circuit. Only works if the throttle is completely closed. On my J230D I close the choke quickly while cracking the throttle open at the same time on cold starts. Check the carbies float cutoff level is correct and make sure that no fuel sloshing compound has got passed the fuel filter. ( it did on mine and the fuel filter was dead clean when I cut it open and inspected it) It's white on the new Jabs and the very devil to remove, you will need to grit blast the fuel bowl to remove it. This stuff doesn't seem to get in the jets but can build up enough to block the entry to the start curcuit.
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Quiet right Nev, I was on L188s at the time. It was actually the cracked engine mount that started the harmonic that took the wing off, there was also the runaway prop problem to get your attention! In fact sounds mad but you actually pushed the throttle full forward to engage the prop locks. All a bit to long on details to explain; but the point was that there was no warning to the pilot until it happened. The lesson I think is if you change anything that changes prop, engine, airframe relationships be very very carefull!
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The hub of the prop is solid composite as are the blades. Rod told me that Jabiru would consider approving it for some applications pending successful testing. The hard part here (stress gauges etc. are costly) is the vibration testing for the 10 or so primary modes of vibrations. I’ve flown in my mates J250 with his nice looking new 3 bladed Petronius (spelling?) prop. Very smooth but the vibrations are quite different, less vibration than the approved wooden props and much higher frequency. It’s the harmonics that worry me; what happens if they build up on say an engine frequency; remember the Lockheed Electras; it tore the wing off! I think I’ll stick to approved props or ones tested by very high time in service in futurensider aproving it for some apllications pending
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I had the same problem on one of the right side leads. The lead appeared to be a little on the short side, came out twice. I put an extra plastic tie to another wire close to the distributor, 100 hours and no further problem.
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I have heard that an outboard motor fuel tank works well. It was a Terrier 100 as I recall, the chap plumbed into the fuel line with a two way tee valve. The engine (Subaru) driven pump sucked the fuel through O K, he even left the prime bulb attached. Of coarse he was Experimental, the chances of Jabiru approval on an LSA would be just above zero I suspect!
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The current Basler model uses the Canadian P&W PT6A-67R so maybe it's not one of theirs.
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Looks like one of Basler's conversions. They started with Darts way back, the current model uses P&W PT6. They carry around 40% more payload than the old DC3 at 210kn. Anyone visiting Oshkosh can have a look at the plant, it's on the other side of the field from EAA.
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Of course you are quite right, I was trying to relate to what a pilot operating normally see's and does; it would take 100's of pages to go thru the physics involved, (including interesting data from Orbital Engines test cell results) the point is that the Bing compensates, the only real argument is how well, considering the price I figure it's not to bad. My EGT's are usually below 700 or less; on a hot day they can go higher (740) after T/O on first power reduction if I don't go straight to 25-26lt/hr. As Jabs Don says you can't have everything. The F/F may seem low but I'm running a Sensenich 62"x56" prop and Hoerner 3.7:1 teardrop type wheel spats, the extra 7-8kn deems to unload the engine considerably, bit like when you do a power on high speed descent. I’ll post more on the spats later still a bit of tweaking to do, but looks like maybe 125kn at 2800RPM and 19lt/hr at 550KG.
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The expert can believe what he likes, dosn't mean it's a fact. I was climbing out of Gympie-Bundy today. At 1000' readings at 100kn 2800rpm. F/F 25lt/hr Manifold Pressure 27" By 5000' at 100kn 2800rpm F/F 18.5lt/hr MP 24". (EGTs 700) Somethings happening, looks like it's leanig as the MP drops to me. Try this on a Lycoming without manual leaning it just doesn't happen. Ran the idea passed the Jab engine guys at Bundy they compared the idea with the brown stuff you find in cattle paddocks. Wouldn't comment on how well the Bing does it though!
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do you use a Glide or Power approach??
Modest Pilot replied to Tomo's topic in AUS/NZ General Discussion
For air-cooled engines a power approach is probably a good idea if you are looking at reaching the recommended TBO. However there's always the chance of an engine failure to consider. During testing the Aerocarb on the Sonex jammed on approach at 600 feet just as an area of high sink rate was encountered. This is a known problem on slide type carbs, the fix being to stop the engine reset the throttle and restart. Seemed a bit sporty at this altitude, so I went from landing to T/O flap setting and comfortably landed. The Sonex flaps have very high drag in landing config. But my J230D will do the same but only just. If you are thinking of doing this even though it's an emergency situation you better have a minimum altitude for config changes, I use 500 feet on the J230. (I use 70kn approach speed primarily for better aileron control so you have 10kn speed to play around with) On the Sonex I use the flare point and before people start jumping up and down, remember the B747 Go Round calls for Go Round Thrust and flaps to T/O position and that can be from under 20 feet! The point being that much depends on the aircraft. -
You might consider a hydralic press. Direct Deals have 6 tonne models for $120. I have a 12 tonne model that I found has lots of uses and has paid for itself many times over. To remove the tyres I cut a hole in a hunk of 10x3 wood with a jigsaw just bigger than the wheel diameter. Lay the wheel on the wood in the press. I use another block of wood just smaller than the rim; you could probably press direct on the hub but you might distort the wheel; and slowly pop the tyre off.
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Caution: This applies to my J230D. After gathering up 100 hours on type decided to explore the envelope a little. You can land wing down 15deg nose yawed by the same amount or combinations of same; and although I wouldn’t suggest slamming the nose hard down on touch down; the aircraft kicks straight by itself without problems. The limit on x-winds shows up later in the roll out, without toe brakes and no differential braking the aircraft rounds up into wind, hence the 14kn limit I suspect. Also the ailerons are pretty weak at low speeds, with really rough conditions I settle on 70-75kn on approach and cheat a bit using rudder to help out on roll rate. Not ideal but that’s life!
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Forgot to mention I blocked off the slot on the oil cooler inlet shroud. That's what lowered the CHTs.
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The polimers that do the good stuff for viscosity also alter the struture of the oil molicules and it doesn't cool quite as well as mono grade oil. I shot for nominal oil temps of 87deg C at 15deg C OAT. You will have to check your oil temperature indicating system first, and the oil may still be hotter away from the sump walls. If you have the old ribbed oil sump it's easy to construct an aluminum shroud over the slanted section (kick it under the bottom an inch or so) using the tapped sump holes to attach. (should stand off ribs 1/8") Rivet a Jab heater flange on the shroud and attach a stiff steering rack rubber cover to the flange and make a 32mm hole in the cowl. Results: CHT 10-15deg F lower. Oil temp 10deg C lower and no extra bits to undo for cowl removal. I have found this setup good 10-38deg C OAT for takeoff, colder and you have to tape the extra cooling hole with speedtape.
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The Service Manual allows 3-4mm of play depending on which control surface. Inspections are required at 1000 hours, replacement at 10,000 hours. I got new pivot washers from Jabiru. They are thicker than the orginals and removed almost all slack in the system. Teflon spray (stuff used on garage door slides) where the cables go through the rubber boots will improve the control feel.
