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Flyingphot "At 5100rpm indicated I only burn about 15 lt/hr which I think should be higher"

Looks a bit like your prop pitch is a bit fine.

David

You certainly need to keep the radio antenna well away from the GPS or anything else for that matter which has has a microprocessor and/or a switch mode power supply. This includes the ICOM power adapter. All this stuff generates crud which will interfere with the mute setting of your radio.

David

It appears that there are plenty of other oils which Rotax also recommends. It in interesting to note that Rotax seem to think that operating with oil temperatures up to 120 degrees C are quite normal. My 912UL was obtained second hand and it took quite a while before I managed to get all the water out of the oil. It had obviously been run too cold and in fact that was the reason why it had seized a big end and broken a con rod before I got it. That is the main reason why I attempt to generally run with an oil temperature slightly above 100 degrees C. It also keeps the water condensate from building up as I do not fly very frequently these days.

David

Just think of what you might have missed out on.

The mind boggles

David

Hey Flyer, next time I am down at Tooradin, I will make myself known to you and you can make this old timer a cup of coffee. I live at Drouin South. 19-1877

Getting back to the Ops Manual bit. It takes long enough to get any changes approved by CASA, without going through all the members too. I imagine that those who represent us have a fair idea of what is needed anyway and while all these new fast birds are arriving on the scene, those of us who fly "real" ultralights, have still got all the privileges they used to have, with a few extra ones thrown in for good measure.

David

Obviously none of you speed merchants has every flown in a Thruster.

Enjoy the view.

David

Peter McLean at Yarrawonga has it.

David

Skyfox49.

Have a look at http://selair.selkirk.bc.ca/aerodynamics1/Drag/Page9.html

and you will see what the drag curve looks like and how it is calculated.

David

I think that we should be asking the RaAus some pertinent questions about why the new Ops Manual is unable to have parts copied from it. All you can do is print it. I don't know whether this is also going to apply to the version which they are sending us on disk.

It does rather restrict any discussion that we may wish to have if we cannot copy and past the relevant pieces into our text.

David

Tony et al,

Do you think we concentrate too much on the stall, particularly with the lighter aircraft, and not enough attention is given to the rate of descent before the stall? If I get my CH701 on the wrong side of the power curve, I can easily get a rate of decent above 1000 feet per minute and still be above the stalling speed.

I get the impression that a lot of heavy landings happen because of this high rate of descent just before the flare, and in the actual flare the wing is not able to generate enough lift to arrest the descent before the ground is encountered. This seems to happen, particularly in short field landings, where a fairly slow approach is required.

David

Would it be reasonable to infer from the above example, that the term "sink" is actually a misnomer, although the effect produced is sink? In the example "sink" is actually caused by "wind shear".

David

I didn't say that my rate of climb straight ahead was different into the wind, I said that the rate of climb in a turn would be different, depending on which way the wind was blowing.

John Brandon, I'm sorry to disagree with you still, but momentum has nothing to do with relative wind direction.

David

In one of the sessions at Narromine we were told that for convenience, CSU and variable pitch would be included in the same endorsement.

David

Ian, look up P4C in Google. Caitlin looks like she will benefit. Don't you blokes give her all the answers, just point her in the right direction so that she can suss out the answers for herself.

Caitlin, just beware that some of these old blokes don't lead you up the garden path.

David

I have the 80 hp 912 in my CH701 and it is quite adequate for getting off the ground with a short strip. 200 metres between the diagonal corner posts of the paddock. The other advantage of the 80 hp is that it runs on standard unleaded mogas. I have flown in a 100 hp 701. It was a bit faster, noisier and used more fuel. You don't need the extra HP. The CH701 was originally designed to use a 503 although a lot of the early ones in the US used a 582.

David

Better to build a tail dragger, then you don't have to worry about the rather agricultural nose wheel setup.

David

The Chinese are already ahead of you there Ben, only I think they use chook crates.

David

Please ignore the previous statements about inertia. I must have been having a Senior's moment. What I meant to say is that it has no kinetic energy.

David

If the bloody thing isn't moving, it has no inertia. What can be simpler than that?

David

"BUT WE DO: The stick will always be at the same position of rearward travel when we stall. This is the stalled stick position. If you don't know where it is on your aircraft then you should. Go and stall and find it. So the stick is in fact the best possible indicator of alpha and it is remarkably progressive and linear."

Not so. That the position of the stick will depend on a couple of different things.

First of all, it will depend on where the centre of gravity is and that may well vary according to what moment the luggage or fuel are producing. It will also depend on how much flap you are using. For instance, my flaps produce a fairly strong nose down attitude, which combined with a CoG in the forward half, results in a complete inability to get the AoA high enough to stall.

Also a reply to another comment.

Inertia has absolutely no dependence on wind, only ground speed. If you are flying your trusty Thruster at 45 knots into a 45 knot wind, your ground speed is nil and so is your inertia.

David

I explained the physics of the situation a few posts back. The same theory also applies to climbing turns for instance when climbing after take off and turning crosswind or from crosswind to downwind. You probably already are operating near full power so there is no opportunity to increase power in the climbing turn, so you must push the stick forward and reduce the angle of attack and rate of climb, otherwise you might well stall if you turn too sharply.

For instance, as a fairly rough approximation, my CH701 with me and half fuel will climb straight ahead at 50 knots and 1600 feet per minute. If I try to do a 2 G climbing turn, I must reduce my rate of climb to around 700 FPM to maintain 50 knots and that is in still air. It gets worse in a head wind, so best not to try it.

David

What is confusing the issue is Newton's First Law of Motion.

" Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it.

To change direction, you have to use energy, in this case, if you are going from upwind to downwind, the energy needs to be somewhat higher. In fact, to go from 80 knots indicated downwind to 80 knots upwind having started with a tailwind of 20 knots, you need to input about 25 percent less energy than if it was the other way around. So, if you were flying at the point of stall before you made the turn, you would theoretically stall if you turned in the other direction without inputting that extra bit of energy.

Even without wind, you still would need to input some extra energy to execute a 180 degree turn. This was why the early Royal Flying Corps pilots were instructed to lose height in a turn, because with the low powered engines, insufficient extra power was available to turn without stalling. The extra energy was obtained by losing a bit of altitude, thus converting some potential energy into kinetic energy.

However, in the case quoted above, a stall is unlikely, because, hopefully Ultralights will be flying well above the stall, unless of course he is flying a 503 powered Thuster two up.

So, beware the downwind turn.

David

Well, I have "been there and done that" at Leongatha in a Thruster. As I recall, I was about to flare, probably twenty feet or so off the deck when the wind suddenly changed direction. I instantly turned into the wind, ready to put it down off the strip, into the wind on the grass, but fortunately, the wind straightened up down the strip again, so I kicked it straight down the strip and landed, much to the bewilderment of the assembled troops who wondered what the hell I was doing, so they ran out and grabbed the wings and walked me to the tie down position.

In hindsight, I probably should have gone around, but it all ended well anyway. In the Zenair 701, I would probably say "%$#@", roll it into the wind, and carry on with the cross wind landing.

David

Although I have the map sitting on my lap, I use the GPS to tell me both how far, what direction and how long to the next to the next waypoint, which is generally a landing strip of some sort. It also tells me my ground speed and automatically adjusts my heading to fly the correct track.

You don't find airline pilots sitting there with a Wizz Wheel working out where they have to go, they use technology, which is much more accurate.

If the GPS goes tata's, I will resort to the map, but that doesn't happen very often.

Why are so many people reluctant to admit that they navigate with the aid of a GPS?

David

"At my 100 knot cruise speed, that also works out to be 10 miles."

Only if there is no wind. We don't all have the luxury of being able to fly at that speed.

David