F10

19 hours ago, Blueadventures said:

You could consider fitting a clear glass inline fuel filter in each feed line at above ear level; that way you can see the fuel fill in the line.  Being factory build I'm not sure about specifics on the fitment.  Cheers.

Yes, a good idea. The Rotax uses Mogas, so I bought two fairly large paper cartridge filters from Supercheap Aerospace....they are in nice clear casings and are large, so as not to effect fuel flow I think. Didn't install them, just held them up, had long penetrating looks at them in the hangar! However, after a bit of added research, paper element filters have issues. The paper retains water apparently, bad in aircraft generally and very bad if it gets really cold! Also, I'm not convinced the filter bodies are strong enough with sun and vibration. If a filter fuel pipe attachment broke off, it would be pretty bad, no fuel feed and as an exciting bonus, an over shoulder bad fuel leak in the cockpit!...They sell smaller sintered bronze element ones, but they are small...not sure it will ensure enough fuel flow, particularly if it had picked up some debris? The other issue is, with the Gazelle, I would have to lengthen the rubber section fuel hoses, coming out the fuel tank, to install the filters. The hoses provide the flexibility in the line, when folding the wings. The fuel filters would get in the way of this a bit. so, still having a long careful look at the filter situation.

The Gazelles only had content markings on the side of the glass fiber fuel tanks. This was "lit up" by unpainted discs on top of the wings, letting light in to see fuel levels. I dare say a bit opaque when new and gets worse with age! I have carefully cleaned up the clear discs on the wing or tank upper surface, which has improved things. Unfortunately, no sight glass tubes installed in the side of the tanks, a far better system.

Sorry, no pics, but had a fun flight to, West Sale-Yarram-West Sale, this last Sunday. Smooth air except for a few kicks near one lonely small Cu cloud over the southern side of the hills. I flew via a waypoint that allows for some open fields FLWOP options, otherwise going DCT you are over dense forests. Fuel was sufficient, planned landing with almost twice fixed reserve...93 kts GS going there. Had a good chat, laugh and coffee with the Yarram lads, visiting pilots in an RV12, and watched a huge "Dromedar" (spelling?) crop duster land and taxi in. On startup, RH tank lower than left, but total still plenty.

Coming home, hit a transparent brick wall...63 kts GS! Anyhow, you like flying don't you!? But then the old Gazelle decided to have some fun with me...and the tanks fed unevenly. Only 1 psi pressure difference will do it...I watched the right tank drain away, like my face colour...to an unreadable quantity level. Then came the question, is it a blocked vent, or fuel line, or her tricks again? over forest, I edged a bit close to those forced landing fields. I kept looking at the fuel pressure light.....trying to force it by sheer willpower to not start flickering! Bit of wing rocking to shake things up a bit, in case...

Then relief....I could see the level had started to drop in the left tank, masses of fuel now! I love flying again! 🙂 finished off with a bit of a greaser at West Sale. Never a dull moment in the Gazelle!  

Update on my hobbs. I removed the gauge and connected it to my motorcycle 12V battery. Lo and behold, a happy ticking sound was heard, with moving number barrels! So, I had a wiring power problem. A good mate came around last Saturday, who knows his way around Rotax engines and who has built two beautiful Rans S12's. He quickly homed in on the oil pressure transmitter on the front of the engine, screwed into the oil pump housing. Turns out the hobbs meter is wired into this. Had two earth wires, one it seems for oil pressure gauge one earth wire for the hobbs. An earth wire was broken and the positive connector needed a bit of tightening. Glad the oil pressure gauge didn't pack up. An oil pressure gauge reading zero would be pretty distracting! Stable temp and a happy sounding motor would suggest a gauge failure, but still...distracting! So after sorting the wiring, all is good with the world again!  

Interesting, my Gazelle uses a type of bracket that clamps on the strut, with a drilled tab on the clamp, to which the jury strut is bolted. I kind of prefer this rather than drill holes into a strut. But these are streamlined struts, teardrop shaped cross section, if this makes a difference. We removed the jury struts to remove some surface corrosion and re paint them. What was an eye opener was how much rigidity the struts lost, which the juries removed. They were quite floppy, but still strong in tension. I think without juries, you could probably get some flutter developing at higher speeds.

8 hours ago, Bernie said:

Mine also had another under the panel for air frame hours from memory only activated once 40 knots was reached.

Bernie.

Yes, so does my Gazelle, hidden under the panel. Used for airframe hours indication, activated by airspeed.

12 hours ago, onetrack said:

F10 - There's nothing in the Hobbs meters that is repairable, simply buy a new one.  When you pull it out, it will have a decal with all the relevant information on it, model number, part number, voltage, polarity etc.

I have several new units of the rectangular variety, but I can't help you with a round one. Try eBay, there's usually plenty available there.

Yes, pretty much made peace with the fact a new one is on the cards. Not he’ll bent on a round one, will be happy to put in a blanking plate on the panel, or fit it in the round hole with a plate. I will PM you about yours if you may be open to selling? Cheers!

Gazelle, so a Rotax 912 80Hp. Not sure of Hobbs brand. Round gauge with numbers and hourglass symbol. Maint manual I have doesn’t have much info.

This is a sad story, that 172 pilot nearly pulled it off, but I’m surprised he never went for the beach. Ditching a fixed gear aircraft, is always going to be problematic, but better than a busy highway. Paul’s comment on opening doors is a good one, so fuselage distortion doesn’t jam them closed. Cherokee’s with their single doors are scary…..! The recent ditching of that Rockwell 114 in QLD I think, is a tragic example. I would have hoped they could have got out.

Yeah, who ever heard of a Hobbs meter failing? Well, mine has🤦🏻‍♂️🙅🏻‍♂️😡 Can anyone give me a bit of info on how it’s wired up? I checked the spade connectors at the back of the unit. One was a bit loose, so crimped it slightly to tighten it up. Sadly, to no avail, numbers remain frozen from last flight. Next step will be to remove it and connect power to it. If it works, guess we have a power supply problem. Fortunately, they don’t seem to be too expensive, if it comes to replacing it. Any advice welcome!

I was wondering, does it matter? You look at a chart, and whatever it says the lower limits are, so be it. Surely ATS can choose heights of A and E, according to what will facilitate traffic control? For example, the C height fans, on approach routes to some regional airports?

Helicopter Wx CFIT incidents are more tragic in that it is frustrating to think, they can land…anywhere! Yes ok, on any relatively flat clear area. Once you’ve pushed it over a forested area, you have a problem…. I would find it hard to understand how any pilot could get into this position in a helicopter…unless twice in my career, trying to clear a ridge, I had judged it ok, having seen the ground beyond, but I had almost been caught by cloud drifting or rolling down, to close the gap. Both times the pulse rate increased markedly! 

Well from practical experience, turning downwind during air shows and in other instances, I’ve had to roll off bank, to reduce my rate of turn, as I’ve noticed my airspeed wavering and dropping slightly as I turned. I put it down to the rate of turn, being too high so as to induce a tail wind component. This is not a large effect, I’m not saying you will wash of 20 knots turning downwind in a 20Kt wind, but I’ve seen the airspeed wavering and dropping slightly. When you are in a low energy aircraft, as I was in this case, we’ll that’s sure what it felt like to me. I still stand by my assertion that be very careful turning downwind with a high rate of turn, low speed, in a strong wind. Let’s say, a Tiger Moth was basically hovering in a 60 Kts wind. Th pilot rolls on 45 degrees of bank and turns through 180 degrees, I think he will notice a drop in airspeed, my experiences says so. Yes, doing leisurely turns on autopilot, isn’t going to show this up. I see one member is keen to paste warning signs on my posts, we’ll that’s fine, I still stand by what I’ve experienced. Won’t comment on this further, parcel of air theory is fine and I accept that in many scenarios, but I think there are some situations that it doesn’t quite cover.

20 hours ago, Garfly said:

 

On this point we are all in furious agreement.

 

But given F10's savvy and experience he must have his reasons for complicating conventional wisdom with his practical observations.

Which is why I asked about the wind-shear 'exception'. I wondered if he meant that a quick 180 is a bit akin to rolling your own wind-shear.

Anyway, the theory around rapid turns within an air mass has long been debated.

Experts seem to disagree; that's nothing new in aeronautics. (Let's not get started on 'How does lift happen?"  ;- )

 

Yes you are quite right we "fly in a moving parcel of air" Wind drift on a navex is explained this way, which is fine. But it doesn't seem to quite fit when we are taking of in a "parcel of air" moving across the runway at 90 degrees...

Same thing here. If you turn rapidly (key word) downwind, your aircraft needs to be able to accelerate with that "parcel of air". Otherwise yes, very similar to windshear effect, turning rapidly downwind, you will see a drop on IAS in a light aircraft. you go rapidly from a headwind, to a downwind. We are talking a pretty fresh wind here, probably in the order of 15 kts. Remember you may be indicating 60 kts, but in a headwind, say after take off, your aircraft mass and therefore inertia, will only have your actual velocity to determine it, your GS in other words. (forget TAS for now, we are low). When you turn rapidly downwind, you have to accelerate your aircraft mass, to maintain speed, to a noticeably higher speed. It resists this due to inertia. Hope it makes sense? (-:

I was at a small country airshow, in South Africa, this guy in a microlight, similar to a thruster, but with a pusher engine/prop, flew down the runway and started doing steep turns in front of the crowd, (rapidly turning downwind). Unfortunately a strong surface wind of 15-20 knots. She staggered around in the first one and he kept turning...I turned back to a mate and said "this guys going to kill himself". As those last words were spoken, I heard the sickening metallic bang. I whipped around and there it was, tail straight up, nose first into the ground. Very not good.  

Another thing I didn't see mentioned but may have missed it...I won't try a turnback under 500 ft in my Gazelle, regardless. Far less distractions and better options for a quick trouble shoot, by going straight ahead. But a major problem with turn backs is the wind. Taking off into a 10kt wind, of course means a 10Kt tailwind on landing. But even more critical, you will have to be able to accelerate in the turn to maintain a safe IAS, as you turn downwind. I am always amazed in a low inertia aircraft, how far down you need to stuff the nose, to maintain speed, turning rapidly downwind. I think there is a rule of thumb, but I would add at least 200Ft for every 10 kts of headwind.  

On 06/05/2022 at 6:51 AM, Mike Gearon said:

I was flying in Alaska with an old bush pilot mid 2022. We headed up a narrow pass and remembering YouTube’s of pilots crashing in the Rockies as they lost ability to climb in mountain passes. I said “we don’t have a choice here do we, can’t turn around” 

 

We then did. A steep descending 180 degree turn around in a float plane!

Yes, angle of bank has no effect on stall speed - unless - you try to maintain altitude in the turn. If you roll to 60, but unload by diving, no probs. get low and slow....and your looking at a forced landing with power, straight ahead.

Firstly, so sorry to hear, I own one and it’s a fun little machine. Not surprised it seems to have sold quite quickly, as it would be a great project if you had the money. I dare say it would be cheaper than buying a new Kitfox kit.

On 20/8/2021 at 5:42 AM, Roundsounds said:

A fairly standard military arrival manoeuvre I am told. Hit the airfield fast, roll on bank and pull some G to decrease speed. Minimises exposure to any ground threats. 

Yeah the anti SAM profile of the C160 Transalls, in South West Africa, would be to come in overhead Ondangwa the main airbase there, at 17 000 ft, pop the dive brakes out, roll over into a very steep bank and in one 360 turn, would be on short final to land, quite a wild ride in the cabin!

The B24 was on paper, technically a better aircraft having the Davis laminar flow wing. Trouble is, it didn’t work too well as being at height on the ground, it was difficult to keep clean, disrupting laminar flow. Also if high and heavy, you had to fly at a high angle of attack, which negated the good aerodynamic laminar flow characteristics of that long tapered Davis wing. But the B24 came into its own in the Pacific theatre, where long range and a good bomb load made it the preferred type. It also suffered from poor directional stability at height, surprising considering those huge twin fins. The Venetian blind type bomb doors were also an innovative feature. It had Pratt’s as-well, a better engine I dare say, than the Wright Cyclones of the 17. Always feel a bit sorry for the old 24, bit of an ugly duckling and to me hasn’t really got the recognition it probably deserved. It’s another Hurricane/Spitfire story!

Yes that is true of the Puma types, they tend to be top heavy as they are quite tall, compared to the far more squat configuration the Seahawk. To exceed rotor tilt limits would take some doing….pilots also feel the edge of rotor limits because you can feel the hammering on the blade droop stops, warning you you are at the limit of cyclic movement.

Unload, unload, unload. Keep sucking that stick back…because the windscreen is full of paddock….and it’s the end.

Eurocopter and spares are problematic, I get that. But all I can say is in South Africa, the SAAF operated Pumas and later the Oryx hPuma airframe with Super Puma engines and gearboxes, upgraded cockpit) for over 40 years, getting excellent service out of them. Yes, the honeycomb floors were soft, but then 5mm super wood load spreader floor coverings were fitted, solving the problem. The aircraft had two big cabin sliding doors, but not the rear ramp which surely is a great feature? Just seems strange that these Taipan helicopters, made by the same people, were so troublesome?

One big culture clash was the loadmaster/door gunner. I believe Pumas and Eurocopter products were never designed to defend themselves in a hot LZ. That’s the orbiting gunships job, and the defence from the troops exiting the helicopter. in the SAAF we flew with flight engineers. They carried out certain flight duties and all loading and field maintenance duties. They were good, they could change an engine, in the bush. To me, a better config than door gunners?

On 27/4/2022 at 11:37 AM, djpacro said:

Quote

Recoveries should consist of throttle reduced to idle, ailerons neutralized, full opposite rudder, followed by forward elevator control as required to get the wing out of stall and recover to level flight. For acrobatic category spins, the manufacturer may establish additional recovery procedures, provided they show compliance for those procedures with this section.

For example, the Pitts S-2A has this cockpit placard:

 

Aileron application can complicate things, but they have interesting effects relating to moments of inertia. This has to do with classic gyroscopic precession. In a steady spin, the pitching moment of inertia has built up. We have a heavy fuselage, pitching constantly, or in effect, rotating nose up. Hold a bicycle wheel out in front of you. Spin it towards you (nose up in other words), now, once spinning, “bank” the wheel (tilt) it over. You will feel, your tilt force, becomes a twist or yaw force, due to gyroscopic precession. If you don’t believe me, let go of one side of your wheel, it won’t fall over, but will rotate around. Yes, you need to spin it quite fast, but a few thousand kilograms of fuselage pitching at 15 degrees a second, has the same effect.
 

In the Mirage 111, you banked the aircraft into the spin by matching the yellow stripes on the stick, to the yellow stripes on the cockpit sills, for recovery. This was using gyroscopic precession on the fuselage pitch moment of inertia, to yaw the aircraft out the spin. The Mirage 111 having a far higher mass in the fuselage, compared to the wings. Weapons on the wings of fighters can radically alter spin recovery characteristics of course.

Unusual in that normally aerodynamic forces are used for spin recovery, but not in this case. Delta wings do have very high rates of yaw, compared to roll, as an autorotation characteristic. Also, the Mirage rolled at 720 degrees a second, it was tricky to discern when it had recovered from the spin, because having the stick hard over, would be rolling it on recovery!

I never flew Mirages, but have chatted to mates who did. I have spun, autorotated and g-stalled Harvards, more times than I care to remember, in the SAAF. She loved dropping a wing on you!

As far as getting the stick forward, you need to make sure you have installed the aircraft, so, keep moving it forward till you do (no more heavy buffet). Stall recoveries normally don’t require you to shove the stick fully forward. But do what you need to do, or your flight manual says to do. If the ground is close, use the space you have, to pull out. Stalling the aircraft again, being in too much of a hurry to pull out, can really ruin your day. Easier said than done, I know.

13 hours ago, Old Koreelah said:

To stay alive you can’t beat good design: having plenty of rudder under the tailplane as well as above it, plus mounting the whole empenage sufficiently far back.  

Yes, Chipmunk, PC9, are examples of a common design feature, to avoid rudder blanking by having the vertical fin, located further ahead of the horizontal tail plane. Known as tail plane stagger.

Sorry, but struggle with this “quote” system!

11 hours ago, djpacro said:

 

 

Cessna's Spin Document notes:

Note the use of the word "may"!

So you recommend simply centralising the controls if in an incipient spin? Before 2-3 turns? AC 23-8A states "Most airplanes will not attain a fully developed spin in one turn." When I demonstrate an aggressive unintentional spin entry with power and aileron it will be fully developed well before 2-3 turns.

 

By all means, if in an aerobatic aircraft and unintentionally enter a spin while conducting aerobatics and take immediate action (so very early in the incipient spin phase), centralise the controls to prevent the spin from developing - it is appropriate then.

 

In my experience, during “g” or “accelerated” stalls, or autorotation induced with aileron lose or at the stall, the aircraft recovers very quickly with centralising controls. The real crucial factor is to unload or reduce AoA, that’s why ideally, get the stick forward of neutral. 2-3 turns of a spin will be considered fully developed when rates of roll, pitch, yaw are constant. In the incipient phase, roll, pitch, yaw are generally oscillatory, and the aircraft will also be transitioning from level flight, to a vertical spiral, around the spin axes. As I said, in the incipient phase, the moments of inertia in yaw, roll, pitch have not had time to build up. This is a generic consideration, some aircraft may well be fully into the spin earlier. But to me, there is a difference between the incipient and fully developed spin, and moments of inertia to me, will take more than 1 turn to fully develop. 
 

at the end of the day, consider an autorotation, occurring in a base leg turn. Without spin training, power to idle, then centralising controls, making sure you unload enough to un-stall the wings, crucial. Most aircraft should recover. In a fully developed spin, most aircraft should recover, with controls held neutral, otherwise to me, they should not have been certified. The reason that positive spin recovery actions are taken, is recovery will be faster. Snapping on full opposite rudder may not be required, and my slight problem with this is, you need to remember to centralise the rudder immediately on recovery, or yaw roll to the opposite direction could occur, and possibly cause an autorotation to occur in the opposite direction. Again, look at the flight manual.

11 hours ago, djpacro said: