Bush Baby

[priester]

Hi Mogas

Thanx for the reply.I am even more confused after speaking to a couple of guys at the hanger today.

The left wheel is 142kg, right wheel 139,5kg and nose wheel 73kg. As mentioned earlier she has a 2.3 vw motor which we started today and she purrrrrs.

What is the max empty weight for mpl?

One seriously overweight lady. According to SAPlanes the empty weight should be 250kg to 280 kg, yours is 354,5 kg. The mauw for the aircraft is 450kg microlight and 500 kg for light plane. This only leaves a payload of 95,5 kg and 145,5 kg. This payload includes fuel and oil.

[Mogas]

Hi Brian
Using a standard nose-wheel BB spreadsheet I get the following: Total empty weight 354.5kg CofG 302.2mm aft of the datum or 23.1% MAC. This is in limits. The limits are 268mm - 373mm
Note: Empty weight means all the equipment normally used, GPS, radio, engine fluids, etc but excludes any fuel. Was the plane empty of fuel?
To be absolutely sure please check the following.
Datum: Did they use the wing leading edge, about where the corner of the open door lines up with the wing leading edge.
Distances of the arms: Do you have these? Nose 615mm fwd of the datum. Main wheels 540mm aft of the datum. These will only be significantly different if you somehow have different gear on there.
Yes, she is a bit porky but about right for a Veedub BB. Definitely falls in the light plane category, max for microlight is 260kg empty.
Mogas.

[Brian]

Photos of "slightly overweight" BB

P1040654.JPG (61.83 KiB) Viewed 2365 times

P1040657.JPG (50.49 KiB) Viewed 2363 times

[Brian]

Serious egg on my face

Previous owner already put juice in for startups
We will weigh again tommor.
Thanx for help and I will keep all interested parties posted

Brian

[KFA]

Hi Brian. I notice from the pic that you don't have a header tank installed. You should seriously look at this. The header tank keeps 5 l of fuel as a 'reserve' for those long descents when you are low on fuel. Because of the nose down attitude and the backward position of the fuel pickup in the tank a situation might arrise where the engine dies of fuel starvation.

[Boet]

Hallo Brain,
Apologies. I went walkabout for a bit. Came back very late last night. VW engines are OLD tecnology. They are also very heavy. The weight look about right for a volla powered BB. If you want it any lighter, buy a Rotax 582. Is the engine direct drive or belt-drive?

[priester]

Serious egg on my face

Previous owner already put juice in for startups
We will weigh again tommor.
Thanx for help and I will keep all interested parties posted

Brian

Of course Ferreira's aviation does not know how to weigh an aeroplane.

[Brian]

Please check my post dated 19 Sept. I have alot of respect for Windham and family at Ferreira Aviation.

I pushed the plane over to their Hanger to be weighed and I was helped in a very professional manner so I dont think we should point fingers now unless this remark was directed at me???

[CFD]

On the C.O.G. issue I have come across many flawed weight and balance calculations and a constant error in this measuring business is not getting the aircraft in the correct 'flying' position.

As the aircraft comes with different sized nose wheels and can be set up differently depending on how much rubber you use in the nose wheel gear suspension, the aircraft all sit on level ground at totally different attitudes. By changing this angle (pressure in the tyres for instance!) by just 1/2 a degree you can get a variation of 20KG on the nose wheel! This has a HUGE impact on your C.O.G. calcs and can lead to false data.

The aircraft must be set up with the wing at an angle of 4.0 degrees to level ground (all the wheel scales need to be the same size also!) as this is the attitude the aircraft flies at and is the only way to get a correct reading. I have seen the C.O.G. point altered by as much as 5% due to small variations in attitude during the measuring stage! It is my guess that there are a helluva lot of BBs (and other aircraft) out there that in truth have way-out C.O.Gs. Luckily these are usually too far forward which at least is safer, but a rear C.O.G. can be deadly! On the bush Baby this out-of-balance is normally trimmed out by changing the angle of incidence of the horizontal stabilizer or by the position of the flaperons. Whilst this may make the aircraft flyable and safer, It results in unnecessary drag and results in a plane that is never truly set up properly and
will have strange flying qualities through the speed range. Most BBs that I have flown tend to be quite nose heavy as they tend to drop the nose quite strongly when you come off the power and a lot of stick pressure is required in a glide.

If you make the effort of getting the C.O.G. correct the plane flies so much faster and better!

The shallow tanks of the BB can be a problem when running low on fuel. With only 10 hrs. on mine I lost the engine in the circuit and had to lob it into a ploughed field - luckily no damage and managed to fly it out with lots of egg on my face! One solution is to affix one fuel outlet at the front of one tank and at the rear of the other tank.

[Mogas]

Thanks for the input CFD, well said.
I did not even mention the attitude at weighing time as it should be known by whoever weighs it that this is the first step and it is of paramount importance that the aircraft is level, left and right, fore and aft.
For the Bushbaby or Explorer take the level reading on the belly along the side of the fuselage near the main gear for fore and aft, along the the bottom of the rear spar carry through for left and right.
Ran out of gas CFD??? do you have a header tank installed? I don't know if you got one with your kit but they are now fitted/supplied as standard for that very reason!

[atom]

Always nice to be a proud new owner of an airy. Well done Brian, may u have many safe trouble free flying hours.
Can anyone direct me to someone who has good knowledge about the 2.1 VW engines used in aircraft such as the BB or Tri-cubby? I am looking at maintenance issues, things to look out for , service bulletins and any other info in general.
Regards
Atom

[CFD]

For those interested, the last 5l or so in the Bushbaby tanks are unusable and only there for show! Soon after getting mine I joined overhead at Contermans with what I thought was still enough fuel, started decending on downwind and the motor quit while only about 200ft a.g.l. (about 15 seconds worth!). Luckily there was a field underneath me and the landing in the very rough newly ploughed field was up a steep slope (downhill would have been tickets as it is so steep no aircraft would ever be able to stop before hitting the fence at the bottom). I stopped in about 30m! Ran 100m to the hangars, put 10l in and flew out taking off down hill after clearing all the rocks. Don't ever count on using that last bit - it is only there to ensure you have enough fuel left to make a good fire!

[ZAZU]

Most aircraft, if not all, have a certain amount of "UNUSABLE FUEL". As Mogas said, a header tank is cheap insurance when the main tanks are low on fuel.

[Brian]

Thanx for the good wishes Atom and everybody else on this forum.

This forum is definitaly the best source of info and advice and I am installing the header tank a.s.a.p

Hope to see you guys soon at a fly in

Regards
Brian

[KFA]

Hi Brian. From the picture it looks like you also do not have the V Brace installed that is required for the nose wheel config. It is not very clear on the pic's, just make sure it is installed otherwise you will seriously damage the airframe and break the nosewheel off. The V brace is a brace installed between the firewall and the floor and attaches at an angle down and backwards from the firewall onto the carrythrough below the floorboard. In the older bushbabies this brace had to be bolted on. The newer ones have them welded in at the factory. If not sure give me a call
Stefan oh eight 2 601 8970