density altitude

[Garfly]

I like this article on the subject of DA / Aircraft Performance:

 

DA EFFECTS ON PERF..pdf

 

 

 

A few highlights:

(screen shots - click for full rez)

 

 

 

 

 

[turboplanner]

For those doing cross country flying, I'd recommend cooling down and waiting for the PPL Module where you'll be taught sequence by sequence to do it correctly rather than the picking and plucking we've been reading among which, if I remember correctly was a great way to have two lots of aircaft flying the circuit at different heights.

 

In the P&O module you'll get exercises in the step by step calculations that come together to become your flight plan (and yes I know that's not the formal flight plan we used to submit to DCA, CAA etc), and most impirtantly you'll be fluent enough to replan in the air for safe transit and landing at an alternate field if the weather ahead of you closes in. etc.

[facthunter]

If you are pushing the boundaries have Ground effect available and don't climb out of it( or try to)  till you don't need it Pilots of Austers learn this quickly as their rubbery U/ C's can propel you into the air on take off earlier than you wish IF the strip is rough. I got called to lunch with this one solly.   Nev

Edited March 30 by facthunter

[facthunter]

 Don't planes now operate at different height's in a circuit ? Pressure altitude is how you separate Plane/Plane BUT that's not as a result of the Baro settings being different.. I knew  a pilot who couldn't comprehend why the Height was showing thousands of feet but the Plane was at electric powerline wire  height as they were "JUST there". He subsequently crashed and burned air passages of himself and the passenger.   Somewhere along the way critical knowledge had not gotten through. Follow up and consolidation is all part of the process. IF you don't understand, ASK..  Nev

[Garfly]

1 hour ago, turboplanner said:

For those doing cross country flying, I'd recommend cooling down and waiting for the PPL Module where you'll be taught sequence by sequence to do it correctly rather than the picking and plucking we've been reading among which, if I remember correctly was a great way to have two lots of aircaft flying the circuit at different heights.

 

In the P&O module you'll get exercises in the step by step calculations that come together to become your flight plan (and yes I know that's not the formal flight plan we used to submit to DCA, CAA etc), and most impirtantly you'll be fluent enough to replan in the air for safe transit and landing at an alternate field if the weather ahead of you closes in. etc.

 

Turbs, I really don't understand your almost religious devotion to the text of that particular PPL O&P module.  

 

Sure, it's good (and something like it is necessary) but just 'doing' a module - once - doesn't guarantee much in the real world.

 

(As you point out, yourself, vis-a-vis the OP video).

 

Anyway, how can 'picking and plucking' (aka, continuing study and consolidation of knowledge) lead to aircraft flying at different heights in the circuit?  Makes no sense. 

 

Also, regarding the need to be "fluent enough to replan in the air for safe transit and landing at an alternate field if the weather ahead of you closes in. etc." :  maybe having some handy rules-of-thumb in your head (and/or checklist) would be even better than those "step by step calculations" you worked through once, yonks ago, to satisfy the regulator that you 'knew' that stuff.

 

In any case, pilots not averse to a little "picking and plucking" might find the Performance rules-of-thumb, cited above, useful, somehow.  I know I did.

 

 

 

 

Edited March 30 by Garfly

[turboplanner]

2 hours ago, Garfly said:

Turbs, I really don't understand your almost religious devotion to the text of that particular PPL O&P module.  

 

Sure, it's good (and something like it is necessary) but just 'doing' a module - once - doesn't guarantee much in the real world.

 

(As you point out, yourself, vis-a-vis the OP video).

 

Anyway, how can 'picking and plucking' (aka, continuing study and consolidation of knowledge) lead to aircraft flying at different heights in the circuit?  Makes no sense. 

 

Thanks, you made my point beautifully.

 

 

[Garfly]

And you mine.  We're square.  

 

Although, you didn't answer my question.

[facthunter]

I never get asked any. Am I writing in Invisible Ink? Nev

[poteroo]

The take-off,  even @ MTOW, used to be less of a problem in PNG ops because most strip's had significant slope. 5 - 10% was usual. But, there was a climb limit for most fully loaded aircraft. I think it was about 6% and was shown on our PK charts. It became a worry if you got airborne ok, but then needed to climb to perhaps 4000ft higher to get through a  ' gap '  We used a rule of thumb to add 3000ft to our pressure altitude to calculate DA. 

[danny_galaga]

On 27/03/2024 at 11:35 AM, RFguy said:

You are right about  luck/skill... The other day I encountered prop wake turb landing right behind a cessna 206 that had done a short fielder (dragging it in at probbaly high thrust) and then  go around (all thrust) .

There was nil wind, and when, in the flare with power off,  I got tossed around--- right at the time I was the most vulnerable (low control authority, low speed) . 

I was like 'WTF ?!  I was tossed around  in roll and yaw. was quite a surprise.

I applied a little bit of power to stabilize, and almost not quite enough as I got lifted up 10 feet in some wierd turb gust and then almost ran out of airspeed . I should have applied full power and turned it into a go around, or at least got airspeed all the way back up and had another go at the landing (there is 1600m of runway ) . I used up a bit of luck..... I've only encountered such turb once before a couple of years ago with some mech turb from a line of hangers downwind somewhere else next to the runway .....

 

Which brings me to this- that it's important to fly regularly- because the more often you fly , the more often you encounter adverse conditions, and the more likely you will have recency -  to competently handle whatever has been thrown at you.

That is to say, if you fly not often enough, you might encounter that prop wake turb once every year, which is not often enough that your brain has recency  to deal with it competently / instinctively. Fly once or twice a week,  and you are more likely to encounter that type of adverse condition  often enough that  it has not been too long since you last dealt with something like that... if that makes sense.

I've actually stopped flying for a while because of this problem. I wasn't flying regularly. Each time I actually felt I was becoming every so slightly less proficient. Really need to fly at least once a fortnight, just to maintain what you have have I reckon. I was often flying less often than that.

[danny_galaga]

On 30/03/2024 at 4:30 PM, facthunter said:

I never get asked any. Am I writing in Invisible Ink? Nev

What's the capital of Bulgaria?

[turboplanner]

29 minutes ago, danny_galaga said:

I've actually stopped flying for a while because of this problem. I wasn't flying regularly. Each time I actually felt I was becoming every so slightly less proficient. Really need to fly at least once a fortnight, just to maintain what you have have I reckon. I was often flying less often than that.

Good perception, good action taken, probably a lot of money about to be saved.

One guy I now solved this by flying 30 minutes every week then went on a decent flight when he wanted to.

The other possibility is that when you can spend the hours, you at least have the financial bundle to do a concentrated two oir three weeks of restraining and get back in the groove fast.

[danny_galaga]

Yep. Been saving a LOT of money 😄

 

But my plane is nearly ready for test flying, so I do need to find a way to get back in shape so to speak. The flying school I was hiring from are on a bit of a hiatus. 

[RFguy]

I fly 0.5 to 1.1  per week to maintain recency. I do it week after week after week....

and that is whether I have somewhere to go or not, "PILOT HAS TO FLY" is my mantra

longer than 2 weeks and the rust starts

like I said a couple of weeks ago, fly regularly and you will encounter challenges often enough that the competence to deal with them stays in your brain.  fly less regularly and challenges overcome etc get lost in time and you dont remember how to deal with it.

 

 

 

[Blueadventures]

17 hours ago, danny_galaga said:

Yep. Been saving a LOT of money 😄

 

But my plane is nearly ready for test flying, so I do need to find a way to get back in shape so to speak. The flying school I was hiring from are on a bit of a hiatus. 

Try some share flying with a neighbour at the airfield with a similar performance aircraft; you may not do the take-off or landing but can refresh some upper air stuff and slow manoeuvres etc.  When you solo in yours wait for ideal conditions the first few flights as you want to get the feel of it that will be hampered in wind gust or thermal conditions

Edited April 24 by Blueadventures

[Garfly]

 

DA strikes again ...

but this young couple lives to tell the tale:

 

 

 

[skippydiesel]

Hmmm! All the camping gear for the romantic weekend plus two "large" adults.???????????

 

When it comes to small aircraft, I am fortunate in my genetic weight characteristics and have often felt really bad about knocking back a request for a jot flight from someone who weighs X 2++ me but you can't fight physics.

Edited July 7 by skippydiesel