SINNERS COME TO CHURCH AGAIN - "WHO HAS NEVER FLOWN OVERWEIGHT" - THESE ARE MY EXAMPLES IN REAL LIFE.

[SSCBD]

 

Sling 2 - Weights for a Sling 2 100hp Rotax injected

Maximum take-off weight 600kg 

Empty Weight 380 kg 

Useful load 220 kg 

Assuming 100 litre of fuel at .72 kg per l = 72kg.

So 220 kg useful load –  LESS - 72 kg fuel (100l) gives a max fuel t/off load available of 148 kg

Say (not being rude - more than a few of us are 100kg ish.

Then I have a Pax say 77kg or up. (Some friends are more)

Plus I usually carry some stuff in the back for example tie downs – headsets – I always have a iPad pro and take a couple litres of water  – flight bag stuff, etc. So let’s guess at 7 kg of stuff. (If camping in the back blocks it would be more in real life)

EXAMPLE

EMPTY WEIGHT SLING 2 OF  380KG

100L FUEL                    72KG

PILOT AND PAX         177KG (weight this trip)

STUFF IN BACK              7KG        

Current - TAKEOFF WEIGHT 636KG -36KG OVERWEIGHT

ALSO  

If I take my mate who is heavy at 113 KG (he checked on scales last time – now on diet) I am "only" 77kg overweight!!!!! (IF I FLEW WITH FULL FUEL). BUT THEN I WOULD HAVE NO FUEL,  IF I TOOK FUEL OUT. 

(Of course, before the comments, I also know take-off distance, stall speed, climb rate etc is affected including adding hot and high density alt) AND C of G.  I can take fuel out but what if you have a long flight out and no refuel ability. I know the should plan but its not the question of have YOU  flown overweight?

The Sling 2 is rated for 700KG MTOW overseas so aircraft is rated for it.

And so is the RAA Jab 230 I believe is at 760kg as a four seat VH version.

So the question stands who has not flown overweight. (in a past life). 

 

Edited October 17, 2020 by SSCBD

[old man emu]

It is about time officialdom came out of its cloisters and looked at the population. 70 kg is eleven stone in the old measure. I passed through 70 kgs while a hairy-arsed youth. According the Body Mass Index figures someone 178 cms tall (5 ft 10 ins) is healthy if their weight is between 60 and 79 kgs. How many blokes that tall do you know who are that light. I'd say the ones of that height we would now call average are between 90 and 100 kgs.

 

If we take into account population norms (no, not that Norm) then the default weight for aircraft occupants should be 100 kgs.  For the Sling 2, the total of the amounts given above would be 659 kgs, with the aircraft known to be OK with another 41 kgs on board.

[FlyBoy1960]

you are making some really big assumptions here about an aircraft being able to be flown overweight in other countries. They may not have the same G requirements as Australia, I believe, our G requirements are based on international standards plus the weather that can be expected in Australia to affect an aircraft during flight.

 

Just because somebody says they fly at 700 kg overseas is probably true but it will most certainly be at a reduced G loading so instead of +4-2 you could be +2-1 in which case your aircraft will either be damaged or break in our turbulence.

 

There are standards and rules for a reason, commonly these are written in blood of those before you.

 

CASA or  RA-Aus has a requirement of a required payload which is one hour of fuel, two persons of 86 kg each and if you add this together and don't have enough payload based on the aircraft empty weight then the aircraft cannot be registered as an LSA and would have to go into some sort of experimental category with CASA. We saw this happen at our airport previously when the RA-Aus came up to measure some aircraft that were being assembled that were obviously much heavier than being claimed, then all of a sudden they went on to the VH register after the RA stickers were removed

[Bernie]

I'm 79/80 Kg depending on when I weigh myself through the day.

Have been this weight for about the last 30 + years or more. I used to be 72Kg prior.

I'm 74 and walk 4 plus Ks each morning .

Guess I'm not normal?

Bernie .

[pmccarthy]

Many aircraft also have a seat structural limit. It might be 110 or 120 kg and is based on the seat not collapsing at a certain g force vertical deceleration.

[cscotthendry]

Who “hasn't” flown overweight?
I haven't.

I saw the result of doiing that just the other day. A Sling 4 was being rebuilt at our airfield. It was flown with 4 adults on board (+ luggage?) and stalled on short final. It went into the ground nose down, upside down.
I don't know what became of the occupants.

[RFguy]

I see it as there are  two main overweight configurations, one downright dangerous, one less dangerous.

 

(1) There is overweight with CofG still in good place.

- EG maybe 2 x 100kg pax and full fuel in a J230 or a Brumby 610 high wing ---(a wet wing overhead  the pax ) 

 

and ,

(2) there is overweight with CofG where it shouldn't be,

 

Both are unlawful  but have very different potential consequences.

I've been reading through the specs for various aerobatic capable aircraft and their CoG limits in either Utility or Aerobatic use, and the aerobatic limits are (CoG limits) are a few percent narrower at each end  to permit the higher probability of  hazardous aircraft  states .  This tells you that a few percent aft of CoG limit in your LSA is putting you into a region where some aircraft states (lateral or longitudinal or whatever, IE say.. vertical wrt to airflow full power etc etc) are no longer reliably recoverable...... 

 

-glen

Edited October 17, 2020 by RFguy

[old man emu]

CofG is probably the crux of the matter, as aircraft structures are built to withstand more than 1 G , the size of the G factor depending on the intended use of the aircraft.

 

However, getting the CofG out of the envelope is the killer, especially if it moves to the rear, creating a tendency for nose-up and subsequent stall. You rarely hear of a CofG being forward of the envelop.

 

In relation to this discussion, stating CofG positions in terms of Percentage of CofG range is obscure. Any example should be presented in actual values calculated from the relevant data. Perhaps someone might do that for their aircraft and the figures can be used as the example.

[RFguy]

OME

I am glad you agree with me. I've done this for a few aircraft and presented elsewhere in this site. You might look at the J230 numbers and comparing what happens- they are a bit on the nose heavy side until the rear is loaded ... Sort of the opposite of the hazards we are discussing here.

 

Might be a good exercise for operators to run some numbers and present them..

 

Alright then... will purify the terms:

" CoG location as a function of percentage of Mean Aerodynamic Chord length...."

-glen

[Bennyboy320]

1 hour ago, old man emu said:

However, getting the CofG out of the envelope is the killer,

My company policy in the airline is that we can’t push back until we have a FINAL load sheet with the correct weights for take off, landing & zero fuel which also includes the appropriate C of G %, it’s served me well all these years & I apply the same personal SOP to my Foxbat flying, except in the airlines we use standard weights e.g. 77kg for a male etc & in the Foxbat we use actual real time weights for everything.

 

The beauty of the Foxbat is that we are 590kg with full tanks, my wife as pax , 20 kg baggage in compartment plus backpack under her legs, weight & C of G NEVER an issue, I LOVE MY FOXBAT.

[pmccarthy]

My wife and I plus full fuel puts the Archer on the nose-heavy limit so I keep some water in the luggage compartment. Am thinking about removing the ADF which I never use, it is heavy.

[old man emu]

2 minutes ago, pmccarthy said:

Am thinking about removing the ADF which I never use, it is heavy.

That's going to involve a re-weigh and amendment to the POH, isn't it.

[pmccarthy]

It can be done by subtracting the weight already in the list, but I would like to get a re-weigh any weigh 🙂 as it hasnt been done for 30 or 40 years.

[Yenn]

The weight of an ADF is not enough to need a re weigh an Archer. From memory a re weigh is required if the weight change is a certain percentage of max weight. From memory it is 5%, but I could be wrong, will have to refer to my notes.

[Old Koreelah]

1 hour ago, pmccarthy said:

...I would like to get a re-weigh any weigh 🙂 as it hasnt been done for 30 or 40 years.

Something we should all do; aeroplanes rarely get lighter over time.

[onetrack]

cscotthendry - Is the Sling 4 crash with 4 POB, that you mention, the one in the story below? The interesting information is at the bottom of the article, headed, "What the Investigators Concluded". 

 

https://www.brisbanetimes.com.au/national/queensland/queensland-plane-crash-survivor-cannot-walk-facing-lawsuits-one-year-on-20180817-p4zy7s.html

 

 

Edited October 18, 2020 by onetrack

[skippydiesel]

1 hour ago, onetrack said:

......................................................................................................................................................................................

Sobering reading. Reinforces the need to be acutely aware of W&B for every "sortie" where weight limits may be be very close/above max OR where a single weight (large person) is boarding.

 

My aircraft is supposed to be able to accommodate 2 X 90 kg persons. I am a shrimp at about 70Kg, fully dressed for the cold, so when I get a large passenger (anyone 90 kg or over) I start to be concerned about  lateral trim, TO/Landing distances & speeds - Sorry but I dont take passengers of 100 kg or over, even though the aircraft is technically within weight limits.

 

[ClintonB]

4 hours ago, pmccarthy said:

It can be done by subtracting the weight already in the list, but I would like to get a re-weigh any weigh 🙂 as it hasnt been done for 30 or 40 years.

My 182 has gained 79kgs from its original POH and last annual, the strangest thing was the guy who weighed it this time, did its initial weighing.

[Bennyboy320]

2 hours ago, ClintonB said:

My 182 has gained 79kgs from its original POH and last annual, the strangest thing was the guy who weighed it this time, did its initial weighing.

He wasn’t sitting in the a/c whilst they were reading 

the weight.🤔

[ClintonB]

I think it is paint- was polished originally, some of the ADF gear, cb, hf, internal coatings all just adding up, but it does eat into payload. I was once told if you can shut the doors it will fly, but not something I want to try.

Edited October 18, 2020 by ClintonB
To finish sentance

[onetrack]

Quote

My 182 has gained 79kgs from its original POH and last annual, the strangest thing was the guy who weighed it this time, did its initial weighing.

Mud buildup inside the spats? A few tools gone missing?   79 additional kgs is a LOT of extra weight, and surely can't be attributed to just paint and a few accessories, alone?

Edited October 18, 2020 by onetrack

[skippydiesel]

Years ago a conversation on this Forum alerted me to collecting stuff in your aircraft.

 

Went out and removed ALL non essential stuff (some of which I had forgot about) - it added up to kilos of not so good ideas to have on board.

 

Probably all crept back by now  but for at least 6 months my little  aeroplane must have had much better performance.

[RFguy]

One thing I want to do is experiment a bit with what happens to the static and dynamic stability of an aircraft as the CoG incrementally  goes aft around MTOW..... There are a few tests you do input and observe the behaviour. and can teach one something.  Even the simple step pitch down or step pitch up inputs from level flight at different airspeeds.

 

[cscotthendry]

Oneetrack:
I wasn't given any more details than what I posted so I can't confirm that is the same crash, but ...
The circumstances sound similar and I imagine there aren't that many Sling 4s about, particularly ones that have been crashed.

[walrus]

RFguy: 

Quote

One thing I want to do is experiment a bit with what happens to the static and dynamic stability of an aircraft as the CoG incrementally  goes aft around MTOW

 

‘I don’t know you, but in friendship don’t try it. The transition when you finally reach the limit of available lift from the tail is likely to be abrupt and could over stress your wing structure. I am in no way an expert but there is no guarantee that the stabiliser is going too stall in a benign and gradual fashion.

 

To put it another way, you could be into a tail slide or at least an uncommanded stall turn. Unless your aircraft is designed for aerobatics it may fail in reversed airflow.