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Jabiru overweight


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Firstly I must declare I don’t own a jabiru aircraft I own a savannah vg with a 2200 jabiru engine but a good friend has I believe a ul jabiru with one internal tank rather than wing tanks but he has hit a problem with the aircrafts weigh. Can someone enlighten me as the aircrafts normal base weight prior to putting in fuel and passenger slit can end up at 450kg

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Firstly I must declare I don’t own a jabiru aircraft I own a savannah vg with a 2200 jabiru engine but a good friend has I believe a ul jabiru with one internal tank rather than wing tanks but he has hit a problem with the aircrafts weigh. Can someone enlighten me as the aircrafts normal base weight prior to putting in fuel and passenger slit can end up at 450kg

Many (most) aircraft become overweight if you fill the seats and fuel tanks.

Full tank and just pilot may be fine.

Many earlier light sport aircraft are over the allowable legal weight with two up and anything over 5 litres of fuel. Many flying schools had to change their training planes after an audit revealed the weight issue.

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Sorry you missed my point with the plane stripped, no fuel no pilot etc the aircraft is 25 kg heavier than the “originally declared weight” this I believe is not uncommon with450kg jabiru aircraft what I was interested to know is what do people do to get round the issue - fly only one up with less than 1 hours fuel.

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A bureaucratic problem needs a bureaucratic solution.

adjust your scales to suit your desired outcome !.

OR

Use a lighter fuel H 1 / helium He 2. LoL

spacesailor

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If you have 2pak paint on her she will be 10-20kg heavier than factory specs. Looks great but way heavy. Builder may have got a shock at the weigh in.

Ken

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2 pak doesn't lose weight from solvent evaporation. Ken is correct. I was very weight conscious when building and guessed at a 6 kg saving from using auto acrylic paint. This estimate was from comparison with an otherwise identical kit being done at the same time.

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Back to basics - in addition to overly enthusiastic paint application, take a hard look at the avionics "stack", carpeting, seat materials, etc. You have to ask yourself - Is it really necessary for a safe flight, can it be removed/left out or exchanged for a lighter option .

 

Oh! and one other thing, its not uncommon for pilots to compulsively add to that emergency response /survivor kit list - that 10 kg socket set could be left on the ground.

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I agree skippy. There is a story about a Jabiru in WA that crashed on its take-off run. The pilot had put his heavy toolbox behind the fuel tank and it over-rotated on the ground. I guess one wing stalled first and it tried to do a spin.

A combination of weight and bad c of g. It would have been interesting to see it happen . Alas, no video.

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I used 2 pak & used about 4 litres for 2 coats. I didn't weight the paint but it wouldn't be 10 kg & probably only 30-40% heavier than acrylic. My aircraft ended up weighing 335kg from an original estimate of 315kg. But I added electric flaps, 2 wing tanks, Matco disc brakes, fully lined the cockpit & the weight included engine oil, headsets & documents.

 

Weight & balance checks are more important that a lot think in a light aircraft. It is dead easy & takes very little time. I have standard data set up in a free E6B app on my phone, add the other things and I know I am within limits.

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Tail heavy is DANGEROUS. it's a loss of control issue. You can get tailplane stalling. Don't go there. Also make sure your load cannot shift inflight, Most planes are like people they GAIN weight, usually gradually. To lose weight you have to remove something significant or use exotic materials in some areas.. Any weight gain is with you all the time every minute you fly . Same with extra drag. The invisible hand dragging you down or back. Nev

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I agree skippy. There is a story about a Jabiru in WA that crashed on its take-off run. The pilot had put his heavy toolbox behind the fuel tank and it over-rotated on the ground. I guess one wing stalled first and it tried to do a spin.

A combination of weight and bad c of g. It would have been interesting to see it happen . Alas, no video.

 

Stupid is as stupid does. (I think that's the saying...)

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IMO modern single pack paints (acrylic lacquer) are pretty good. Easy to touch up too as you can get some put in a couple of spray cans. Go single pack and save the weight. Weight is everything in a powered aircraft, particularly if you are stuck with stupid legislated arbitrary weight limits.

My BD-4 was painted with two pack but knowing what I know now I'd go single pack.

Also to save weight investigate Earth-X LiFePO4 battery instead of lead acid. There's a few kilos right there.

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Hi,

I own a Jabiru LSA, empty weight of 270kg and with max weight of 430k. It doesnt give much to play with.

So I can put 2 average people in, min fuel and taxi round a bit, or a lightweight pax and enough fuel for joyflight, or by myself with 65 litres and overnight bag.

We have enquired about increasing the weight limit to 470kg, but were told that there wouldn't be any weight increases available on these older models. So we play with what we've got!

Hope this helps

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I think that C of G and weight distribution only matters on aircraft that don't have all flying tailplanes. All flying tailplanes will keep the stability right up to when the tailplane stalls in both the downward AND upward lift situations. This is one of the biggest advantages of this configuration of aircraft. This means that the pitching moment generated by the wing can be positive OR negative. We flew a Sapphire ( which has the same symmetrical section design as my Grasshoppers, Stingrays and Morgan Aeroworks aircraft) at 66% with no noticeable difference in stability or control. I wanted to go to 99% but the owner chickened out! The symmetrical all flying tail doesn't generate the high coefficient of lift that the "flap" effect does on a TP/elevator system does but it does fly at the minimum drag for the wing/TP situation therefore lowering the overall drag of the aircraft. I can't understand why so many Morgan aircraft are flown at such forward Centre of Gravity's! The ingrained thinking that forward Cof G equals safety is not always correct!

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Perhaps you might tell us how you handle a plane that has a stalled tailplane when it has positive lift? (regardless of whether it's a full flying tail or not.) Full flying tail is difficult structurally and tends to be twitchy and be more subject to flutter also. Nev

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...Also to save weight investigate Earth-X LiFePO4 battery instead of lead acid. There's a few kilos right there.

Very true, but that may significantly change CoG location. Relocating toolkit, tiedowns, etc. may be neccessary.

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Most simpler aircraft fly with a download on the tailfeathers. It's less efficient than optimum, but more stable. Some long ranging aircraft have fuel that can be moved around for more efficient use of the lifting ability of the "back wings" but that's pretty critical and not for amateurs.. Nev

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