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Brodie

Ra-Aus BAK Exam

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Hi,

 

Does anyone have any advice for the Ra-Aus BAK exam? (Content / Possible Questions).

 

Thanks.

 

 

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Because one day something you learn may save your life, I'd recommend studying every aspect until you get it 100%. I know that's a drag, but it virtually never comes up again in your flying career unless you get into a marginal situation like pulling too tightly into a turn.

 

In my case straight after solo after being shown some aerobatics and how to fly below ground level up a drain, I decided to try some low flying across a swamp at six feet at 100 kts. Worked a treat until I looked up and saw a row of pine trees on the far bank - about 80 feet high and stretched out each side of me. I was way too late to turn, so pulled the stick back.

 

The nose rose for a while then stayed at about a third of the height of the trees, speed has washed off to near stall and I knew I would have to lower the nose.

 

Like a lot of people have experienced, I realised I was going to die in the next 30 seconds and my past life started to scroll in front of my eyes.

 

Then something from my BAK study dropped out.

 

I won't tell you what I did just yet, but let's see if you can work it out; shows both the value of BAK and of completing the study of it before your first solo.

 

 

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Switched off the Flight simulator. LoL

 

spacesailor

 

FAIL

 

 

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You lowered the nose reducing the induced DRAG and out climbed those xxxxing trees.?

 

 

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You lowered the nose reducing the induced DRAG and out climbed those xxxxing trees.?

 

I was in too close for that.

 

 

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Firstly; You should have over-flown the intended area for the possible obstacles, in this case the trees. As this was failed to be applied, you could have followed Power, Attitude, Trim. Or, you could have lowered flap to increase lift and decrease the stall speed. Could you let me know what your recovery action was. ?

 

 

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Mate just sign up to https://www.pilotpracticeexams.com/  do all the practice exams on the when you can pass them with 100% or close enough you will kill your real exams with points to spare. that how I passed mine about 6 months ago, I still jump on to stay refreshed.

 

Cheers

 

Rick

 

 

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Firstly; You should have over-flown the intended area for the possible obstacles, in this case the trees. As this was failed to be applied, you could have followed Power, Attitude, Trim. Or, you could have lowered flap to increase lift and decrease the stall speed. Could you let me know what your recovery action was. ?

 

Pretty much right on Brodie. 

 

I remembered that slowest forward speed and maximum climb was full power and full flaps.

 

I was already at full power, but with full flaps the Victa went up like an elevator and I easily cleared the trees.

 

Caution: This is subject to complying with the POH. The Cessna 172 full flaps are about 40 degrees and you most likely woul just bog down. Some Jabiru models Eg J170 also have flap angles too steep to do this.

 

 

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I remembered that slowest forward speed and maximum climb was full power and full flaps.

 

Pretty unlikely.

 

Flaps add heaps of drag, to give a better angle of climb they would have to allow you to slow down more than they impacted your rate of climb e.g. 10% less climb but 20% reduction in stall speed would give you a better angle of climb. But it seems unlikely that flaps could reduce the stall speed enough without adding too much drag.

 

The POH will have the answer, does it require flaps for best angle of climb? (Which is different to an obstacle clearance takeoff.)

 

Flaps will certainly allow you to get off the ground sooner, if you are already flying they will not help you climb.

 

 

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Pretty unlikely.

 

Flaps add heaps of drag, to give a better angle of climb they would have to allow you to slow down more than they impacted your rate of climb e.g. 10% less climb but 20% reduction in stall speed would give you a better angle of climb. But it seems unlikely that flaps could reduce the stall speed enough without adding too much drag.

 

The POH will have the answer, does it require flaps for best angle of climb? (Which is different to an obstacle clearance takeoff.)

 

Flaps will certainly allow you to get off the ground sooner, if you are already flying they will not help you climb.

 

I wasn't talking about a theory, I was talking about a fact, something which happened.

 

 

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Sure, but I suspect that you would have made it over without flaps as well. It was the "slowest forward speed and maximum climb was full power and full flaps" bit I was querying.

 

Particularly in a BAK thread. It's not generally true, and shouldn't be taught in BAK.

 

 

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Sure, but I suspect that you would have made it over without flaps as well. It was the "slowest forward speed and maximum climb was full power and full flaps" bit I was querying.

 

Particularly in a BAK thread. It's not generally true, and shouldn't be taught in BAK.

 

I already mentioned I could only get the nose about 1/3 up the pine trees; there was no way it was going to go anywhere near getting over the pine trees.

 

Once again you're talking your own theory.

 

 

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Many small GA airplanes have their best angle of climb with some flap deflected. Some require flap to comply with CASA's climb requirements of CAO 20.7.4.

 

 

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Generally, whatever flap setting is recommended in the POH will not only improve take-off performance, but will also turn out to be necessary to produce the Best-Angle-Of-Climb - important if trying to outclimb anything.  CASA talk about Take Off-Safety Speed, which is usually higher than your liftoff speed, but just under BAOC - aircraft is not pitched into climb attitude until TOSS is reached. Once clear of obstacles, the flap is retracted, sometimes incrementally in hot, rough air, and the aircraft then speeds up until it reaches Best-Rate-Of-Climb speed. Attitude is then adjusted, trimmed, and BROC maintained until 1st power reduction - which will necessitate a lower nose attitude to hold BROC.

 

It would be quite unusual to use 'full' flap for take-off, or for any maximum rate climb because of power limitations in most of our aircraft. (My RV is something of an exception to the rule - it has 190HP up front and can do an exceptional takeoff with full flap - wet or dry, sandy surfaces).The choice of flap extension is usually 10-15 degrees - however, it's been my experience to use a rule-of-thumb measurement of take-off flap as being whatever the 'down' aileron is at. Seems to work well in most types.

 

After seeing a PA-28 continue a take-off toward trees, and progressively raise it's nose - then collide with them and kill 3 people, I ask pilots why they cannot consider a slight turn away from trees or obstacles with time to spare. I know the rules say no turns below 500agl, but why be fatalistic when you can do something about it? An early, balanced, 10 AOB turn from even 50 ft can avoid a nasty confrontation  with greenery. The aircraft doesn't 'not fly' in these situations. The laws of aerodynamics apply, and you give yourself distance and time to climb clear.   

 

happy days,                                                      

 

 

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Many small GA airplanes have their best angle of climb with some flap deflected. Some require flap to comply with CASA's climb requirements of CAO 20.7.4.

 

Full flap would be unusual though?

 

There is folklore that I have heard a number of times that the best way to clear an obstacle is to put in full flap as you fly towards it. Sure, the aircraft is initially likely to balloon. But what happens then? Maybe you climb away - depending on the airspeed and the aircraft, maybe even at a greater angle. But depending on the airspeed (e.g. too high) you could even sink again. So you really need to time the flap input. When it works, people are around to tell us. When it doesn't, maybe not...

 

I hope this is technique is NOT actually being taught as part of BAK. 

 

 

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I already mentioned I could only get the nose about 1/3 up the pine trees; there was no way it was going to go anywhere near getting over the pine trees.

 

Once again you're talking your own theory.

 

Every time I line up on the runway I rely on the theory of flight, I haven't been disappointed yet. If you feel you have discovered situations where the theory doesn't hold, people would be interested.

 

Just pulling back at 100 knots and trading altitude for airspeed should give you about 200 feet by the time you're down to e.g. 70 knots. You can try this at altitude if you don't believe the theory. Setup for 100 knots straight and level, pull back into a climb without touching the power - by the time you are down to 70 knots you should have gained 200 feet.

 

 

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Full flap would be unusual though?

 

Yep, but as others stated, whatever the AFM states.

 

The Airtourer’s flaps do not deflect very much, incidentally, and the ailerons droop too.

 

In a Husky I’d use full flap and their flaps are very effective.

 

 

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Every time I line up on the runway I rely on the theory of flight, I haven't been disappointed yet. If you feel you have discovered situations where the theory doesn't hold, people would be interested.

 

Just pulling back at 100 knots and trading altitude for airspeed should give you about 200 feet by the time you're down to e.g. 70 knots. You can try this at altitude if you don't believe the theory. Setup for 100 knots straight and level, pull back into a climb without touching the power - by the time you are down to 70 knots you should have gained 200 feet.

 

Refer post #2  "saw a row of pine trees on the far bank - about 80 feet high and stretched out each side of me."

 

I only needed to balloon 74 feet

 

QED

 

 

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Yep, but as others stated, whatever the AFM states.

 

 

 

It was me who said that.

 

Refer post #2  "saw a row of pine trees on the far bank - about 80 feet high and stretched out each side of me."

 

I only needed to balloon 74 feet

 

QED

 

 

 

I wasn't suggesting that you crashed, just that it wasn't a technique that should be taught in BAK.

 

70 feet is a big balloon. The technique was demonstrated to me when I did my PPL, from memory the typical balloon was 10-20 feet. It was supposedly a way to clear fences, not trees.

 

You can't create energy from nowhere. The energy for a balloon comes from airspeed. Flaps may be useful if your airspeed is low enough that trading it for altitude puts you at risk of stalling. However in that case you only have energy available equivalent to the difference between stall speed with and without flaps, which isn't 70 feet worth in our aircraft. If you started at 100 knots and had 70 feet worth of balloon energy, the elevator should have been sufficient. If the flaps cause extra drag, you will end up with more energy at the top without them.

 

However flaps might change the trim enough that the aircraft pitches up with less elevator input, giving the impression that the flaps produced the climb.

 

Consider the situation in this thread:

 

 

 

For maximum performance (recommended for high density altitude), he needed flaps 0 and 59 knots. Instead they had flaps 10 (flaps 10 recommended climb is 56 knots) and 65-70 knots and at the high density altitude they weren't climbing.

 

Do you think dropping full flaps would have helped them over an obstacle? It might have given them 10 feet if they timed it right, but then they would have been sinking rapidly.

 

As I said in that thread, know the configuration that gives best performance and the speed you have to fly to achieve it. You can put that in the BAK.

 

 

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1. It was me who said that.

 

2. I wasn't suggesting that you crashed,

 

3. just that it wasn't a technique that should be taught in BAK.

 

4. You can't create energy from nowhere

 

5. Consider the situation in this thread

 

1. You weren’t the only one.

 

2. Dunno what you refer to. I’ve come nowhere near crashing wrt this thread topic.

 

3. CASA decides the content of BAK.

 

4. I know about energy.

 

5. Not interested.

 

 

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1. You weren’t the only one

 

....

 

Serves me right for trying to reply to 2 messages in one post rather than double posting. Only #1 was referring to your message. The rest was in reply to Turboplanner.

 

My argument is with the assertion from Turboplanner that: 

 

from my BAK study...

 

 

 

... I remembered that slowest forward speed and maximum climb was full power and full flaps.

 

 

 

I doubt that that information is in BAK because it is often not true. (You would know better than I what is in the BAK, I am happy to be corrected.)

 

The full flap balloon over an obstacle is often (wrongly I think) taught as a way to get extra obstacle clearance over the POH/AFM technique.

 

Either way I don't think using full flaps for obstacle clearance is good information to give to a student studying for BAK.

 

 

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