Weight and balance course.

[Guest Redair]

Greetings each, haven't been here for a while, but this thread caught my eye. I too spent an excessive amount of time reading through all the blurb on the W&B course... and still managed to fail the final exam. No excuses here, but I found the way that some of the questions were phrased was somewhat confusing, I will refrain from saying that they were deliberately misleading to trip up candidates, but to my way of thinking, the point of this whole thing should be to educate and ensure safe operation of our aircraft, not to try and trick people into giving wrong answers. Also, the mix of US, GA, Commercial and Recreational reading material in the course, must surely go to further confuse the you-know-what out of students because of their contradictory regulations. We are going to weigh RA Aus aircraft, then let's just learn the rules and regs. that pertain to these aircraft. Plain, simple and precise.

 

I wonder how many people have built their own aircraft, have correctly weighed, (with the inspector present) that aircraft, and who now have to take an exam which they may fail, due to confusing content or questions. The worst of it is, that without the feedback, we cannot know if, or where there are deficiencies in our knowledge, or if there are mistakes in the exam... don't laugh, it has happened before!

 

Repair.

 

 

[diesel]

I draw and keep a simple straight line map of my aircraft. The lever arms for everthing are marked about the datum.

 

The main ones can be constaint or adjusted as per a heavy pax.

 

Weight x arm equals moment

 

Sorry my tablet wont let me lay it out but very simple.

 

If you work out what you can safely carry you

 

are well on the way.

 

With fuel and luggage being the biggest variable.

 

Know what adds to aft c of g.

 

One old addage that kept a lot of pilots alive was when heavy, if you are climbing dont turn.

 

If you are turning dont climb.

 

Chas

 

 

[spacesailor]

Redair

 

Thank you!. I've given my flight training away, due to the stupid bureaucracy in the exam papers, as I haven't the education to understand the complexity of some of the questions.

 

Who ever heard of "carburetor-icing" being caused by "moisture in the air".

 

It makes Darwin NT, the worst place to fly piston engine planes,

 

and

 

The McMurdo Dry Valleys in Victoria Land west of McMurdo Sound in Antarctica the best

 

The question was in my "Basic aeronautical test.

 

I failed!, Yet I passed the online test, which counts for zip.

 

spacesailor

 

 

[facthunter]

Sorry, but moisture in the air IS the "essential" ingredient for carb icing. The south pole may not be the best place to fly but you won't get carb icing there as it's one of the driest places on earth. Nev

 

 

[turboplanner]

I draw and keep a simple straight line map of my aircraft. The lever arms for everthing are marked about the datum.The main ones can be constaint or adjusted as per a heavy pax.

Weight x arm equals moment

 

Sorry my tablet wont let me lay it out but very simple.

 

If you work out what you can safely carry you

 

are well on the way.

 

With fuel and luggage being the biggest variable.

 

Know what adds to aft c of g.

 

One old addage that kept a lot of pilots alive was when heavy, if you are climbing dont turn.

 

If you are turning dont climb.

 

Chas

Great idea Chas.

 

One forum member posted that on one occasion, all he head done was put a 15 kg tool box in his Morgan, but it went out of control on takeoff, and he was very lucky that he was able to recover it and get it back on the ground quickly.

 

The simple calcs you do would pick that up; a minor relocation and you're back within the envelope and no drama.

 

That calculation will also tell you when you're over the envelope for take off and flight.

 

 

[spacesailor]

Facthunter

 

I said Darwin was/is the worst place to fly, with up to 90% humidity.

 

The Antarctic the safest!.

 

As long as your petrol didn't freez.

 

spacesailor

 

 

[facthunter]

I must have misinterpreted what you meant. for which I apologise. The matter should be cleared up though. Airframe icing is very much related to OAT indication even taking into account the temperature rise due speed through the air where it's significant. Carb icing could happen at 30degrees C if you are unlucky. The cooling is caused by expansion of the air through the carburetter (adiabatic, with drop in pressure) and the latent heat of vaporisation of the fuel which would be worse if alcohol was in the fuel. Nev

 

 

[spacesailor]

HEY

 

Nev,

 

That,s what I said, "The cooling is caused by expansion of the air through the carburetter (adiabatic, with drop in pressure) and the latent heat of vaporisation of the fuel."

 

It was deemed wrong, as they were theorizing wing icing on a jumbo at altitude,

 

No mention of any temperature at any time, just moisture content.

 

For a RAA test it's Despicable.

 

spacesailor

 

 

[facthunter]

You can know too much to pass some of these tests. The designer of the tests should try hard to reduce or eliminate that likelihood. I've experienced this situation myself. You have to ONLY refer to the books they set the exam on, to do well..I've also set plenty of multichoice exams and set up surveys both of which require much more effort to do properly than is often the case. This makes people NOT respect the system as it becomes a FARCE. You don't have to know it. Just PASS the exam . That has repercussions..Nev

 

 

[aro]

"The cooling is caused by expansion of the air through the carburetter (adiabatic, with drop in pressure) and the latent heat of vaporisation of the fuel."

The cooling is happening all the time - I suspect the thrust of the question was what is the difference between conditions where you get carb ice and conditions where you don't?

 

 

[facthunter]

It varies The pressure drop is least when the engine is WOT and pulling (On load). Most at closed throttle but less volume involved. The latent heat of vaporisation is associated with high fuel flow rates. and how rapidly it's changing from Liquid to vapour and where that is happening. IF it's injected near the intake port there's no effect The more remote the carburetter (longer intakes) the worse the effect.. It's quite complex to quantify. CASA have at various times printed an image of the situations (environmental) where icing may occur. It's pictorial/graphical and gives a good practical understanding of the situation, which if you get a greasy grip of, it will make you think "today, I might get Icing". Nev

 

 

[M61A1]

HEYNev,

That,s what I said, "The cooling is caused by expansion of the air through the carburetter (adiabatic, with drop in pressure) and the latent heat of vaporisation of the fuel."

 

It was deemed wrong, as they were theorizing wing icing on a jumbo at altitude,

 

No mention of any temperature at any time, just moisture content.

 

For a RAA test it's Despicable.

 

spacesailor

You can have all the cooling you like, and it can vary all the time, and any other variable you can think of, but you won't get ice without moisture.....

 

 

[Yenn]

I remember doing a multiple answer test where I was wrong because I said less than full throttle was more conducive to icing than WOT.

 

Funny I have had icing while taxiing in cold damp conditions, cleared it with carby heat and then taken off WOT and no carby heat.

 

 

[facthunter]

Wide open involves more fuel to vaporise and the mixture is richened as well to aid that. Some engines use alcohol to clear icing. Spray into the intakes. Big stuff mainly. Nev

 

 

[spacesailor]

M61A1

 

Are you saying that at minus 40 degrees C, in "Antarctic's Dry Valley", you will never ever get icing in your "Cessna" carburetor.

 

Not even frozen petrol

 

I have seen a "Petter" single cylinder diesel that wouldn't spray from the injector because of the fuel not going through the nozzle, too cold, had to heat the fuel & lines.

 

At Ashbourne Derbyshire England.

 

spacesailor

 

 

[M61A1]

M61A1Are you saying that at minus 40 degrees C, in "Antarctic's Dry Valley", you will never ever get icing in your "Cessna" carburetor.

Not even frozen petrol

 

I have seen a "Petter" single cylinder diesel that wouldn't spray from the injector because of the fuel not going through the nozzle, too cold, had to heat the fuel & lines.

 

At Ashbourne Derbyshire England.

 

spacesailor

Even if your petrol froze, it's still not carburettor icing. When was the last time you saw a single cyliinder Petter diesel in an aircraft?

You might want to quote the exact wording of the question, in the exams I've seen, they ask something along the line of " what operational conditions would carb icing be likely to occur?"

 

Although you may be correctly describing how icing occurs, that wasn't the question.

 

 

[spacesailor]

"What causes icing

 

simple question, as I was studying RAA flying, Not super sonic, semi space-ship, miles high jet liner,

 

I automatically Assumed "Carburetor icing".

 

But some of the other questions were also relating to commercial aircraft.

 

spacesailor

 

 

[diesel]

You will get carb ice just by starting your engine. Make sure it is clear before giving it the jandle. It saves an embarrassing mess just off the paddock.

 

Yes diesel will freeze / wax. Like petrol there are many grades around the globe.

 

In NZ BP tell us its good down to minus 7c in winter grade. Additives can be purchaced to improve.

 

Jet A to minus 40c.

 

A few months ago I flew my diesel at minus 7c with no drama. Well that was ground temp.

 

Chas

 

 

[diesel]

Hi Mick.

 

The reason your friend ran out of an injection pump would have been no lube in the jet A.

 

All is well if at least 1 % of oil is added.

 

HDI wont need it. However I would still do it.

 

I add a bit when I remember even with diesel.

 

Made a typo above. BP winter fuel in nz south island should be fine to minus 14c.

 

However I would add some thinners before then.

 

43 hrs airborne hammering and old Peugeot diesel around the sky without issues.

 

Now to add heaps more. 12 litres per hour.

 

Chas

 

 

[spacesailor]

NZ has or had the world record for a "Hoar frost" , broke the branches off the fruit tree's, north of the "South-Island".

 

spacesailor

 

 

[facthunter]

I've had a diesel die on Hotham overnight with the lowest temp being only minus 4. Didn't have winter diesel in it. Long ago here where I live we had tree trunks above 8 cms dia explode at minus 12 . Don't get temperatures anything like that now. Nev

 

 

[diesel]

Close to home minus 27c was the temp.

 

Central Otago.

 

If it works in Russia and surrounds it must be good if it even starts.

 

Years ago they had big diesel radial engined helicopters.

 

Not sure what exam papers they used.

 

May have just been orders to fly.

 

Chas

 

 

[facthunter]

Firepots under the engines etc. Shell told me to just add Kero but that's over twice as dear and eventually is worrying for the injectors/pumps unless you add two stroke oil or such. Nev

 

 

[pylon500]

?

 

Meanwhile, back at the weight and balance test topic....

 

Logged into the members portal to do the test, and the first thing that happened was the password I got, was in confusing font, where I had to decide if I was looking at a 1, a small L, a capital I, and then a zero, or an Oh?!

 

Managed to log in the third time.

 

Then spent an entire afternoon trolling through all the mixed info from various official sources;

 

1975 D.O.T. (Australia) weight control regs,

 

2011 CASA maintenance regs,

 

1945 FAA AC 43/10 weight section,

 

2009 Some word doc discussing W+B,

 

CASA exemption 49/15,

 

And assorted video's.

 

And then delved into the test questions and finally the exam.

 

So, anyone that knows me, knows I've got a pretty good handle on most aspects of design, thus weight and balance, I've been weighing and assisting weighing for a few years now.

 

I will be the first to admit that over the years I've got a bit lazy, and now days I use an excel spreadsheet to do all my W+B work.

 

It's a good app, and I understand how moving things around effects things, and know how to adjust things in the app.

 

Naturally I figured if I've got to check some figures, I'd just use the spreadsheet.

 

Two things popped up;

 

⁕I overlooked that the actual figure questions were purely mathematical, yes, you need to draw columns and crunch numbers,

 

⁕The diagramatic aircraft as pictured is basically improbable in the real world. (Don't try to work out the CofG as a percentage as real designers would)

 

The latter being the problem that slowed me down as I tried to reverse engineer the plane to get logical results.

 

End result, failed!

 

No feedback, so idea where I went wrong.

 

Gotta re-engage my old brain and try to learn all the 'different' ways of doing what I've been doing for the last thirty odd years....

 

 

[diesel]

Mmmmm, progress is a strange thing.

 

Chas