Isn't it important anymore?

[Old Koreelah]

1 hour ago, old man emu said:

Honestly, with access to the several graphs present in a POH, there is no need to have even a modicum of arithmetic ability. Just follow the instructions in the POH.

Thanks for your efforts OME. What about home-builts? 

 

I understand the need for a standard way of doing things, but it doesn’t take into account those of us who “think differently.” If I do things a different way and achieve a satisfactory result, why not?

 

I once got into a heated argument with a good friend. After she explained something in terms that made sense to her, I processed her words and explained it back to her in terms that made sense to me (and others nearby). She became progressively more enraged that I couldn’t use her exact wording and could not accept my need to express the concept in any other terms. (I discovered later that our birthdays are close; maybe a factor.)

1 hour ago, old man emu said:

Here's something to think about. If your bladder can take it, and you decide to fly until you've only got your 45 minutes' reserve left in the tanks when you land, it might be possible that the W&B is outside the envelope. Who calculated W&B at the end of a flight?

 

I believe it’s now only 30 minutes, but good point. Some aeroplane’s have their fuel tanks far from the CoG.

Regarding bladder range, I’ve learned not to drink green tea before flying; it goes through me in about fifteen minutes!

[old man emu]

1 hour ago, Old Koreelah said:

 

I understand the need for a standard way of doing things, but it doesn’t take into account those of us who “think differently.”

I hope I'm correct in thinking that you mean by that statement that you are making a distinction between the way you think and the way I do. Let's say that you think using the graphs is the best way to ensure the balance is correct, but I say that doing the calculation is the right way. As long as we both get an answer that's within the envelope, does it matter that we got there differently? No a jot. 

 

1 hour ago, Old Koreelah said:

What about home-builts? 

I would have thought that the designer would have provided the datum point and forward and aft limits. But then I think of the plans I have from a 1930s magazine for a Gere Sport (one was built at Cowra). I don't think I saw any of that data in the article, so I wonder how the bloke at Cowra worked it out. When I go through the  drawings and notes for Arthur Butler's BAT-2, I'll have to keep my eye out for that date.

[old man emu]

1 hour ago, Thruster88 said:

That POH looks like the Australianized (and more shit) version of what the manufacturer would have provided.

It must have been produced in Australia as the VH- part of the aircraft identity was already printed on the page before the individual letters were typed on.  Maybe some older person here might know the bloke who did the weighing - B.D. Linard

 

 

[skippydiesel]

9 hours ago, aro said:

True... both are likely to be lower than 90 for common RA aircraft. 90 kts would be for higher performance aircraft e.g. Cirrus, Bonanza are probably somewhere around there. For our aircraft (<45kt stall speed) somewhere around 65-70 seems more likely.

Aro! where have you been hiding - my last aircraft ATEC Zephyr/Rotax 912 ULS climbed out @t 1k/min, Max TO weight @ 90 knots. My new aircraft Sonex Legacy/Rotax 912 ULS , Max TO weight, climbs out at well over 1k/min at 90 knots. The limiting factor in both aircraft is keeping the engine rpm at or above 5200. Want to stress the engine go for an 80 knot climb, want to keep it cool 100 knot/Zephyr 110-120knot/ Sonex

Edited May 23, 2023 by skippydiesel

[aro]

37 minutes ago, skippydiesel said:

my last aircraft ATEC Zephyr/Rotax 912 ULS climbed out @t 1k/min, Max TO weight @ 90 knots

Sure - in normal operations a higher speed "cruise climb" is fine.

 

But if you're not climbing, Vy is the speed you need. Speed above Vy is not your friend (unless you are overloaded, when a few knots might be helpful due to induced drag equations). Vy might be the difference between climbing away and crashing.

 

ATEC list 110 km/h i.e 60 knots as "optimum" speed which I assume is Vy. About what I would expect.

 

If you NEED the performance, you NEED to fly the speeds.

[onetrack]

OME - One B.D. Linard features in two photos of RAAF 102 Pilots School Course graduation, Aug 1977 - May 1978.

 

https://www.radschool.org.au/Course Photos/Pilots/102Pilots.htm

 

https://www.radschool.org.au/

 

However, there is no further detail available, and he doesn't appear to be a member of the RAAF RadSchool Association. Perhaps an inquiry to the Association may produce something, there is a contact page on their website.

[old man emu]

I wonder what the AN35 signifies in his identifier block. The weighing was done ten years after the pilot's course, so he had probably left the Service.

[RossK]

11 hours ago, aro said:

ATEC list 110 km/h i.e 60 knots as "optimum" speed which I assume is Vy. About what I would expect.

 

A quick google finds the Atec Zephyr 122 Flight manual.

Section 5 lists the Best rate of Climb as 1180ft/min at 54knots, MTOW of 472.5kg.

I have no doubt the Atec are great aircraft and the book performance numbers are better than most, but Skip does seem to flavour the numbers with a bit of bias.

[skippydiesel]

11 hours ago, aro said:

Sure - in normal operations a higher speed "cruise climb" is fine.

 

But if you're not climbing, Vy is the speed you need. Speed above Vy is not your friend (unless you are overloaded, when a few knots might be helpful due to induced drag equations). Vy might be the difference between climbing away and crashing.

 

ATEC list 110 km/h i.e 60 knots as "optimum" speed which I assume is Vy. About what I would expect.

 

If you NEED the performance, you NEED to fly the speeds.

Aro - In real life there is a difference between  a sustained Max climb &  standard everyday practise which is likely to be  a combination of  the aircrafts capabilities. Other factors also must be included - prop pitch, density altitude and TO weight . All my home departures were short field (due to obstacles), rotate at about 40 knots, remain in ground effect to approximately 60-70knots,  initial steep climb (few seconds) to be well clear of tress, lower nose to 90-100 knots for sustained climb 5200-5300rpm/1000ft/min. The overriding factor was/is to keep the Rotax spinning at - above 5200rpm & below 5800 rpm. When using a conventional airfield the initial steep climb was not initiated , all climbs were conducted at around 90 knots, to circuit height and then 100 knots to altitude.

[skippydiesel]

5 minutes ago, RossK said:

A quick google finds the Atec Zephyr 122 Flight manual.

Section 5 lists the Best rate of Climb as 1180ft/min at 54knots, MTOW of 472.5kg.

I have no doubt the Atec are great aircraft and the book performance numbers are better than most, but Skip does seem to flavour the numbers with a bit of bias.

See above Ross - sure you can achieve "the book" Max Climb figures, which if habitual, may result in  a shortened engine service life - pilots choice.

 

In Australia Max TO weight was 545kg (from defective memory) the figures you quote are for the European  theatre.

 

FYI The Zephyr ceased production in 2021 (I think) - the Faeta is even more capable than the Zephyr (at both ends of the flight envelope) but I still would not be making a practise of the Max Climb performance figure.

 

These aircraft use Rotax 9 engines not Ly/Cons  - they don't enjoy being lugged.

[old man emu]

Don't forget that the figures given in the manufacturer's POH are performance at sea level in the International Standard Atmosphere (15C and 1013 hPa). Everyday, and throughout the day, an aircraft's performance will be changing as the atmospheric conditions around it change. 

 

I reckon that a Toora (1300 AMSL) on a morning when the temperature was Zero and there was a typical autumn High pressure cell sitting over Central NSW, a brick would climb like a fart in a bath.

[facthunter]

Your example stinks.   Nev

[facthunter]

Home sick Angel's is nicer.   Nev

[RossK]

Back to the topic.

If you're flying your own aircraft regularly, I doubt most pilots are doing the calcs or plotting the graph every flight.

I've done the calcs and plots for my aircraft and know that my wife and I, 25kg in the baggage area and 95L of fuel are under MTOW and within the envelope at all stages of flight.

So the 3 things I do are confirm fuel qty, actually weigh the stuff going in the baggage area, and then politley ask my gorgeous, stunning, love of my life what she weighed that morning 😱 😲 😬, If the numbers are within my limits, were good to go.

I know that 95L is going to keep the Rotax spinning for 5.2 hours, which is far longer than I can cope. We are typically on the ground again in less than 3 hours (longest to date is 3.5hrs).

Edited May 24, 2023 by RossK

[onetrack]

Quote

politley ask my gorgeous, stunning, love of my life what she weighed that morning...

You truly do enjoy living a dangerous life, don't you?!

[aro]

8 hours ago, skippydiesel said:

In real life there is a difference between  a sustained Max climb &  standard everyday practise 

We're not talking about standard everyday practice.

 

We're talking about what you do when... 

On 23/05/2023 at 1:18 AM, Area-51 said:

one stinking hot humid day with a pax on board a go-around was elected and with full power the bird was not climbing

[old man emu]

5 hours ago, RossK said:

then politley ask my gorgeous, stunning, love of my life what she weighed that morning 

That's why wives and girlfriends can never be convinced to go flying with you.

 

Body mass is something that I have never been asked about when being given a seat in a light aircraft, and a few years ago I had more than I do now. When I look at the specs for an RAA plane I always see how much fuel it can carry with two 120 kg bods in it.

 

Years ago, it was standard practice to use 75 kgs as the default weight for a passenger. Now I would prefer 100 kg because the  average body mass of the population has risen over the past 50 years.

 

[facthunter]

Put it back on the deck  or stay in ground effect. IF you are going to hit a fence ground loop into wind. You can't do it the other way. With a bit of luck you may stop or get close to it in quite a short distance.  Nev

[facthunter]

I think that figure was allowed for RPT where you have the numbers to average it out. (unless they are all SUMO wrestlers) For individual pax OR  small numbers it is ACTUAL. Wt.   Nev

Edited May 24, 2023 by facthunter
expand

[Old Koreelah]

Samoa Air says charging passengers by weight is 'concept of the future' | Samoa | The Guardian

WWW.THEGUARDIAN.COM

---

Airline defends 'pay what you weigh' ticket policy, saying families have been particularly pleased by cheaper child tickets

 

[turboplanner]

53 minutes ago, old man emu said:

Years ago, it was standard practice to use 75 kgs as the default weight for a passenger. Now I would prefer 100 kg because the  average body mass of the population has risen over the past 50 years.

With motor vehicles, the vehicle is not going to fall out of the sky and the passengers are a much smaller proportion than in an aircraft where mass becomes a limiter of Light Commercials and trucks.  The mean has grown from 75 to around 95 kg, but the pub test is a vehicle leaving the depot so design is for actual masses which includes full fuel and pax.

 

Same goes for aircraft; actual pax mass and actual fuel mass loaded.

 

What hasn't been mentioned in the WB calculation is maximum landing fuel.  School and Club aircraft which are mainly flown around the training area and are likely to be taken out from full fuel to near empty tanks are likely to be untility models with the felxibility to do that job without time wasting calcs for every flight. They will be usually be operating within their envelope for school training. However, when you progress to cross-country flying and higher performance aircraft, they are usually built for flight endurance and don't necessarily have that utility design. You might get full pax on a short flight, but you can only load part fuel and limited baggage with full pax, or you can load full fuel, but have to drop 1 or 2 pax, or you can take any baggage. In addition to this your Mass calculations will include your MAXIMUM Landing Mass, which is one of the reasons why doing your fuel burn calculation at regular intervals is important. You may have a sick passenger, but you may have to burn fuel for an hour to come down withing the undercarriage capacity.

 

 

 

[Area-51]

1 hour ago, aro said:

We're not talking about standard everyday practice.

 

We're talking about what you do when... 

"What ever it takes".

 

As one great instructor of mine once answered above to a question presented during EMT training regarding emergency situations and keeping the aircraft flying, away from the ground, and heading in the opposite trend of any, of any unusual attitude occurring...

 

"What ever it takes"...

[Area-51]

I will add this as well.. Had I not recognised my inadequacies as a fresh GA/Raa pilot and taken myself off to gain more advanced EMT training that day being described above would probably of ended very very tragically...

[aro]

"Whatever it takes" isn't much help if you don't know what it takes. What it takes is Vy. That's why the number is in the book. Vx, Vy, best glide - they are documented for a reason.

[aro]

42 minutes ago, turboplanner said:

School and Club aircraft which are mainly flown around the training area and are likely to be taken out from full fuel to near empty tanks are likely to be untility models with the felxibility to do that job without time wasting calcs for every flight.

C152 and Jabiru are both 2 seaters where you may not be able to carry 2 people and full tanks. It's often said any aircraft where you can fill the seats and the fuel tanks should have bigger fuel tanks.

 

What is the smallest aircraft where maximum landing weight is less than maximum takeoff weight?