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Crash Landing in Cunnamulla - two hurt.

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Crash Landing in Cunnamulla - two hurt.

Old 27th Mar 2014, 04:12
  #101 (permalink)  
 
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OK, this took 25 minutes (perp notes and calculations) while having breakky and a phone call interruption.

My point here is, and I am formally addressing this with ATSB is that with a little specialist knowledge these things can be given a much higher quality safety message. The current report is a lowly level 5, so it does not get any serious analysis and its nothing more than a rporting of information sent in.

My thought is that is a waste of time unless the report spells out the flaws or the reasons in what led to the accident so others can learn from it.

The ATSB is under financial pressure to reduce expenses, and they do not have any piston specialists anyway, so a priority is applied, and these reports get done as simple as they are. My frustration is it would not be hard to gain some knowledge in house or at least seek out where that specialist help is externally.

So lets begin with my back of beer coaster study (no beer was consumed with my muesli )

Departure was from Lilydale at 2.20pm and the exhaustion occured at 7pm abeam Cunnamulla some 580 miles north. The average speed was around 124 knots, and safe to assume a bit of tail wind was enjoyed.

Using fuel flows as a prudent well educated pilot would I believe the following would be a fair assessment. Take off flow Approx 59LPH and using a target EGT leaning in the climb a final flow rate would be around 40LPH. If left alone the volumetric flow rate change during the climb would have the FCU delivering maybe 10% more as the DA increased, so the effect of not leaning very well in the climb Vs doing it well is only going to be a few litres. Note this is for a Lycoming and a TCM is different.

With a climb of around 90 knots TAS average and say 20 minutes approximately this would yield a climb stage of 30 miles and 17 litres. Again subtle changes would have little affect. This means 550 to run from TOC to abeam CMU.

Guesstimate of TAS at the claimed 65% power and with know spats, based on POH performance data would yield about 115 plus or minus for spats etc. or lets say 110. Not that it matters much as GS is the critical key here, which was in the early 120's.

Using a best range fuel flow for the selected power/speed required, the engine would be set to 10dF LOP and burning 26-26.5 LPH. This is pretty much what the pilot claims he was told when he rented it. I believe the value to be correct advice, provided you knew how to operate the engine.

The range then would be calculated roughly as 30 miles for climb and a further 6.33 hours at 124kts GS as 790NM. YBCV is 678NM so this was achievable with a bit over over 55 min. reserve. But it had to be done right.

However, 65% power with Poor mixture control could be anything at that height ranging from say 33LPH at 75dF ROP to around 45LPH. I do not have the actual data but I do not think you can get any more than that into the engine at that height.

Based on 45LPH the range would be down to 480 miles or even at 33LPH around 660 miles. The pilot managed a distance of 580 miles so less the climb, that was 550 miles of cruise in 4.34 hrs (4.67-0.33 hrs), for an average of 38.7LPH.

The pilot seemed to be a Jabiru flyer so perhaps not much mixture knob experience and that would explain a lot when he claimed he leaned it, but who knows how much. And with so many pilots afraid of the red knob I can believe it. Heck I think back to when I was learning to fly.....nothing of value in the red knob education at all.

So it is all very believable how he got to where he was, and without an accurate fuel flow gauge or a very good margin for error, this was a bad decision passing Bourke.

Important to note that no pilot can trust the POH of any aircraft manufacturer when it comes to engine matters. Seriously they can't be trusted. So many are found to be either contradictory from one page to another or completely wrong. There is nothing to argue here, this is fact. The problem is which ones can you trust? And which parts can you trust, and the only safe assumption is trust none. They may well be accurate for take off charts and other procedures, and I am not in a position to critique them there, but in engine performance related sections you are foolish to believe everything you read. The secret here is to know how to critically appraise them. About 1-2% of pilots are. That leaves 98%, and very few instructors if any are in the 1-2%.

Case in pont in the Piper Warrior POH there are graphs that show performance for 55/65/75% Best Power Mixture, and for this example lets say the 75%
power as shown in the example. There are 75% best power and 75% Best Economy with two different TAS (122 & 118).......WTF?? 75% of 160HP is 120HP and iff you apply 120HP to that plane with the same prop, you get XXX.X knots TAS. How is it possible to get two different numbers? Simple answer it is not.

What is more they supply two different fuel flows to achieve each of these power settings, and that is fine but if you take the 65% power setting the Best Power which one can only assume means around 75dF ROP is 8.8GPH or 33.3LPH. They also show a 65% power Best Economy flow of 7.5GPH or 28.4LPH. Well the best BSFC for the engine will be slightly LOP, and at these powers around 10-20dF LOP which typically on the O-320 is found at 6.98 GPH or 26.4LPH.

Is it any wonder pilots have no idea? Given all the expertise has long gone from most organisations and it is all turbine/jet focussed is it any wonder ATSB are no better when it comes to good reports.

Last of all, and this pilot did not have the luxury of time to do this, but how often is the usable quantity IN FLIGHT tested? How do you know that the supposed 185 litres claimed to be usable is actually usable. The POH suggests 181-182 litres, but even then how can you trust this. The only way to know is at least once a year just prior to its annual is run a tank dry and refill. Best not to do both during the same flight if you only have two .

None of this is taught for PPL or CPL at any school I am aware of and it is certainly not in any texts.

The reason we do not have more of these problems is possibly through good luck than good training.

The Safety messages that should come out of the ATSB report are;
1. The importance of having accurately and regularly proven usable in flight fuel checks.
2. Having a decent engine monitor fitted and fuel flow with totalisation.
3. Pilots educated in proper engine management techniques and to be able to critically think when reading a POH. Having the understanding of engine fuel requirements and what the real leaning techniques are and how they should be applied.

Happy to take questions. Disclaimer: The above calculations are based on a very quick study over brekky and using my iphone calculator. I have not allowed for known weather, descent and any other small impact factors as they probably have no significant effect on the outcome. I could have made mistakes too as I have not double checked anything.
I'll continue the appreciation trend. I never really have much to weigh in on these discussions but I read everything you post very carefully and enjoy taking on the knowledge. Thanks Jaba, keep it up.
BlatantLiar is offline  
Old 27th Mar 2014, 05:35
  #102 (permalink)  
 
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Creampuff, you said…..
If I need the aircraft to do something specific, like go a very long way without running out of fuel, I make the fan produce whatever thrust is necessary to produce an IAS that corresponds with the minimum drag speed.
A laymans interpretation of that statement is..
For max range fly min. drag speed.
Yes for nil wind, perhaps but not necessarily for tailwind and No for headwind.
Your statement, as written is WRONG.

As to your last post statement.
So, if you need maximum range while flying into a significant headwind the IAS for minimum drag will be different from nil wind conditions.
You are being mischievous, because that is not anything I said, rather a deflection to cover up your own weakness on the topic.
'Min Drag' is not 'Best Range', in a headwind.
When you said,
You are absolutely correct Trent 972 and I realise the error of my ways.
You should have stopped there, because the rest of your writings are just bullish!t and fancy.
Stick to the law. If you were a flight Instructor, I would ask for my money back!
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Old 27th Mar 2014, 06:23
  #103 (permalink)  
 
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Then educate me, rather than having a little tantie.

How do you calculate the speed to achieve maximum range in a headwind?

Let’s assume the IAS at which a particular aircraft – let’s call it a ‘Warrior’ - at a particular weight achieves minimum drag is 80 knots.

I want to fly as far as I can in:

- Nil wind

- 5 knots head wind

- 10 knots head wind

- 15 knots head wind

- 20 knots head wind

- 25 knots head wind

At what IAS should I fly, in each of those prevailing conditions, to achieve maximum range?

Let’s simplify things and assume the weight remains constant.

I say 80 knots. You say I'm wrong.

Fine. Prove it.

Always happy to stand corrected.
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Old 27th Mar 2014, 07:01
  #104 (permalink)  
 
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There is some very useful analysis of data and the laws of physics here: http://www.nar-associates.com/techni...ide_screen.pdf

The ‘rough approximation’ is to add a quarter of the headwind velocity, to maintain the maximum distance speed.

Hence the answers to my questions above are:

- Nil wind: 80

- 5 knots head wind: 81

- 10 knots head wind: 82

- 15 knots head wind: 84

- 20 knots head wind: 85

- 25 knots head wind: 86

See Trent: It’s not that hard!

I stand corrected.
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Old 27th Mar 2014, 07:24
  #105 (permalink)  
 
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You're welcome, and what's even better, you did it by yourself.
Now go and write it out 100 times before sunrise, or I'll come back and cut your Balls off.

edit.

I would suggest that the data you referenced is for a BE-33A, with a max range cruise in the 115 - 120 knot range, and with your example of 80 knot max range cruise, I would expect something closer to half (or even a bit more) the headwind component should be added.
However that is only a guess, I have not done the numbers.

Last edited by Trent 972; 27th Mar 2014 at 07:45. Reason: now having read the link posted by cream puff.
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Old 27th Mar 2014, 07:59
  #106 (permalink)  
 
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The irony is that my posts are still far more educational than yours …

So, the (corrected) statement is: If you need maximum range while flying into a significant headwind, fly the IAS for minimum drag plus a quarter of the headwind component. (The paper at the link also talks about how to adjust for tailwind component to get maximum range in a tailwind. For Trent: I interpret the paper as saying a quarter is the better approximation, for wind fractions up to a quarter of the nil wind best range velocity. So maybe at 25 in 80 the adjustment should be higher, but others 'fit' ...)

And to get back to the subject of this thread, none of this was considered by the PIC of CCQ. Had the aircraft been flown at the IAS for minimum drag, whether or not it was adjusted a couple of knots for the wind component, the aircraft would have made it with fuel to spare.
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Old 27th Mar 2014, 08:15
  #107 (permalink)  
 
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That is where you seem to miss the point Creampuff.
If the pilot of that flight was faced with a 25 knot headwind component, following your befuddled concept of range flying, it would have gone quiet about 220nm short.
Sorry lawman, more work required for you. The educational content of your posts so far have been D-.
edit.
Not wanting to bore everyone to death with our little to'ing and fro'ing I've added my reply to Creampuff here.
If he’d flown at the IAS for least drag, adjusted or not for wind component, he would have made it with fuel to spare.
As a person who spends the vast majority of his work time 'range flying' it is obvious to me that you Creampuff, are quite happy in your ignorance and nothing I can say will change your mind, even though you have already admitted to Standing Corrected. Continue on in your ignorance, blissfully unaware. I will be content if some of the young ones reading this thread give a little thought to the rubbish you have posted so far on range flying. Goodbye.
*Just one thing before I go.
Taken to extremes… How far will you travel in your PA28 with a 80 knot headwind at YOUR max range cruise speed, and how long will it take you to reach your final destination with full tanks. bibi

Last edited by Trent 972; 27th Mar 2014 at 08:53.
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Old 27th Mar 2014, 08:28
  #108 (permalink)  
 
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He wasn’t faced with a headwind, 25 knots or otherwise. It appears he had a slight tailwind.

Did you not read the report?

If he’d flown at the IAS for least drag, adjusted or not for wind component, he would have made it with fuel to spare.
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Old 27th Mar 2014, 09:10
  #109 (permalink)  
 
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Can someone please explain to me some concept here, if minimum drag is at a speed, of say 80kt, how is going faster into a headwind, with increased drag, going to extend the range available. I dont understand.
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Old 27th Mar 2014, 09:29
  #110 (permalink)  
 
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Arnold, click on the link in Creampuff's post 6 posts above.
Not a bad dissertation, remembering the stronger the H/W component and/or the lower the IAS, the greater the effect.
The basics are, as you go faster your drag will increase, but the exposure time to the headwind over a set ground distance will decrease. The relationship is not linear. Somewhere between the 2 extremes is nirvana.
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Old 27th Mar 2014, 10:45
  #111 (permalink)  
 
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What I don’t understand, Trent, is why you don’t use your vast experience in long range operations to explain why I’m wrong and, thereby, to educate others.

I’ve quoted, in this thread, an article by John Deakin in which he talks about ‘extreme long-range work’. Happy to be convinced that what he says about what do when the mission is 'extreme long-range' is not correct. (Indeed, I reckon he’d be happy to be convinced he’s not correct.)

I stand by my statement that had CCQ been flown at the IAS for minimum drag, whether or not it was adjusted a couple of knots for the wind component, the aircraft would have made it with fuel to spare. Lots of fuel to spare.

Sure it would have been a much longer flight, but at that speed the fuel consumption would have been at a much lower rate (if the pilot understood how to lean properly, which is the first issue I raised in my first post in this thread …).

After all, that’s the point of maximum range speed, is it not?

The PIC wasn’t dealing with an 80 knot head wind or a 25 knot headwind. He was dealing with no wind or a slight tail wind, during a flight over a long distance for that aircraft.

Please Trent, educate everyone else and explain why flying at minimum drag speed would not have resulted in CCQ arriving with fuel to spare.
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Old 27th Mar 2014, 10:51
  #112 (permalink)  
 
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as I understand it faster speed into a headwind means the increased drag is overcome by the reduced time. It'll still increase your fuel burn regardless...
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Old 27th Mar 2014, 11:07
  #113 (permalink)  
 
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Creampuff,
Nice try, "educate others", because you're far too clever to be educated.
1. I only entered this discussion to point out a statement made by you was WRONG, it still is WRONG and will always be WRONG, no matter how much you try to deflect. You even admitted you were WRONG after self educating yourself, even though you still haven't recognised the magnitude of your misunderstanding.
2. You said that the accident aircraft subject of this thread would have arrived safely even if it flew at 80 knots plus a few knots even with a hypothetical 25 knot headwind. Guess what you're still WRONG.
I called you on advocating a method of 'range flying' that is incomplete, incorrect, ignorant and WRONG.
Email Deakin yourself and tell him that range is not affected by a headwind component and he will tell you, you're WRONG.
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Old 27th Mar 2014, 11:09
  #114 (permalink)  
 
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Hempy you are CORRECT. What Creampuff seems unable to differentiate in his mind is the difference between endurance and range.
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Old 27th Mar 2014, 11:26
  #115 (permalink)  
 
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You said that the accident aircraft subject of this thread would have arrived safely even if it flew at 80 knots plus a few knots even with a hypothetical 25 knot headwind. Guess what you're still WRONG.
That is not true.

I have never said that.

However, now that you mention it, I will calculate whether a Warrior could have made the distance at an IAS of 3 knots above the lowest drag speed, with a headwind of 25 knots.

(Did I sleep with your wife/girlfriend? I’m trying to get to the source of the anger.)
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Old 27th Mar 2014, 11:28
  #116 (permalink)  
 
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Hempy

Correct (on my meager understanding).

But the adjustment factor for wind effect on lowest drag IAS to get maximum range in e.g. a Warrior is only a few knots up to, at a stretch, a dozen if the head/tail wind is 25 knots.

During the flight the subject of the report, the difference would be a couple of knots, if any.

But the important point is this: We’re talking about vastly different IASs.

HYPOTHETICALLY 80 knots (lowest drag) versus 100 knots (preferred/planned/glossy brochure cruise).

The extra speed above the lowest drag IAS costs FUEL. It usually doesn’t matter much, unless the flight is towards the limits of the aircraft’s range.

Like a trip from Lilydale to Southern Queensland in a Warrior ….
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Old 27th Mar 2014, 11:48
  #117 (permalink)  
 
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Originally Posted by Trent 972 View Post
Hempy you are CORRECT. What Creampuff seems unable to differentiate in his mind is the difference between endurance and range.
Well, as I understand that, endurance is how long the donks will keep turning, which might be important if I was oh say up looking for a 777, but if I wanted to fly a long range flight like say YLIL-YCMU in one hop I'd rather care about how far I could go (with thrust) not how long it took. But thats just me.

Last edited by Hempy; 27th Mar 2014 at 12:10.
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Old 27th Mar 2014, 13:24
  #118 (permalink)  
 
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Hempy

Be careful listening to Trent.

‘Endurance’ is indeed about ‘how long the donks will keep turning’.

But there are many variables that affect when the donks will ‘stop turning’ and how far down track the aircraft to which they are fitted will be when they do.

The donk in question in this thread is one fitted to a Warrior.

Let’s assume 25 knots headwind

Lowest drag IAS in a Warrior at MTOW is about 80 knots.

Apply a headwind of 25 knots and assume our adjusted-for-headwind best range IAS is 85, for a ground speed of 60kts. (Trent (correctly) says that the adjusted speed should be around 92, but let’s not complicate things at this point by making assumptions in my theory’s favour. We could complicate things more by taking into account changing weights and climb fuel consumption etc, but let’s not, at this point.)

500 nms at 60 knots is a very long way. At a constant 60 knots GS it would take 500 minutes or 8 hours and 20 minutes.

With 180 litres usable on board, you’d have to burn less than 22 litres an hour to make it.

And how much do you have to burn to maintain an IAS of 85 knots in a Warrior?

Well jigger me with a bargepole if it’s not: “Less than 22 litres an hour”! You wouldn’t land with much more than fumes - those operations are called “W8”.

Let’s assume no headwind

Given that the actual aircraft appears to have had a slight tailwind in real life, let’s assume it didn’t (because otherwise the assumption would be in my theory’s favour).

Best long range speed is the lowest drag speed for nil wind: That’s 80 knots.

500 nms (on the same assumptions) is 6 hours and 15 minutes.

With 180 litres on board, you’d have to burn less than 28 litres per hour to land with fuel.

To maintain 80 kts IAS in a Warrior, you don’t have to burn anywhere near 28 litres per hour.

Trent will hopefully help us out by explaining where and why my calculations are wrong, rather than merely asserting they are “wrong”.
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Old 27th Mar 2014, 13:37
  #119 (permalink)  
 
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Thank your for the concern, but to be honest when I fly I generally only care how fast I'm going
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Old 27th Mar 2014, 13:41
  #120 (permalink)  
 
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Ahem. YLIL - YBCV (via YBKE, only a couple of miles off track) is 677nm.
Want to run those numbers again! Oh, and you really should add a bit for reserves too!
ps
I'm glad to see your method now includes what you learned earlier today from being held to account for your lack of knowledge on the subject. You're getting there….. but very slowly..

pps
the "assumptions in my theories favour" gave me a little giggle too.

ppps. The figure of 220 nm short I gave earlier was just a spur of the moment guess, but I've since run some more realistic burn figures including climb and taxi burn and it came up with 211 nm short. Sorry about that sloppiness.
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