IBob

We use Red Island.
There are lots of boutique oils in NZ, but the prices are daft.

We haven't bought Italian oil since analysis a few years back revealed that most of the contents bear no resemblance to what the label says. And that includes the big name brands.
Oh and somebody did a long article about what a racket it is over there.......and why it is near impossible to police. The opening paragraph described a ship leaving somewhere in the Eastern Med with a load of some sort of vegetable oil, by the time it docked in Italy it had miraculously transformed into olive oil..............)

I can't find that article, but here's another that gives the general idea:
https://www.oliveoiltimes.com/world/mafia-olive-oil-on-60-minutes/50203

Neil I don't think it's a new idea at all. Just new to me.........😳
I think the tubes used are acrylic, but that thin pneumatic tube would probably work just as well, and would be more readily available.
 

I saw a clever manufactured one recently. It had a transparent tube about the size of a drinking straw, you dip it in then put your finger over the top end, draw it out and the fuel level stays in the tube to be read against the marked strip it is attached to. For now I'll fool around with what paints I have, see if I have anything that doesn't dissolve or flake when dipped in petrol.

11 hours ago, Marty_d said:

If you lightly oiled it, would it still work (and not wick?)

Worth a shot too, Marty, but I'm pretty sure the oil would wash out.

What sort of paint did you use, kgwilson?

On completion of my build, I made a dip stick for dipping the tanks. I made it from matai, which is a NZ native timber, reasonably dense, fine grained and resinous. I spent some time on it and was pleased with the results.
However, it doesn't work as well as it might: the fuel wicks up the wood and I have to be quick and careful to see the wetted part, otherwise it is easy to get an artificially high reading.
Is there some sealant that I could use to prevent the wicking?
Alternatively, what would be a better material for making another one?

On 23/03/2022 at 5:58 PM, Flightrite said:

There sure has been some ugly A/C over the years!😂

Some of the folk who fly them don't look too good either.......)

They are........that or Aircraft Spruce.
And they are a very tight interference fit in the Rotax...I froze them, greased them lightly, then pulled them into place in the Rotax before mounting anything to them.
So sort out the required bolts and spacers to pull them all the way in before going to the freezer...)

A note to add here:

The ICP manual says to weigh for W & B with no fuel in the aircraft.
You cannot fully empty the wing tanks with the aircraft sat level.

Also just lifting the nose a bit (I had it on a bit of 4 x 2 so 2" high) does not renew the flow to drain the remainder, probably due to unavoidable undulations in the pipework in the wings.
To fully drain the wing tanks. sit the aircraft back on it's tail.

Scroll to last entry here:
https://www.rotax-owner.com/en/912-914-technical-questions/8008-fuel-return-line-for-a-912ul?start=10

Area51 I think you're missing my point: I'm not disputing whatever may have been quoted above, I'm wondering what size orifice they are using for that sort of flow.
My Savannah has individual tank valving, but returns only to the RH inner. And I can guarantee that the return rate is not a fraction of the figure you mention.

Skippy has taken some actual measurements on orifice size vs flow.........where is he when we need him?

Area51 yes I know Rotax have a recommended return line orifice.

But 2L a minute doesn't pass the reality test: that's about a cupful every 6 seconds, go fill a cup in 6 secs and you will see there is no way that volume could come out of such a tiny hole...

Come to that, why would anyone design an engine that takes 17LPH in cruise, and circulate fuel at 135LPH???

FlyBoy certainly friction losses may be a significant element, though they are far more noticeable with higher flow rates.
 

I believe the difference of pressure in separately vented tanks to be far more relevant:
Eg: The fall from my fuel tanks to my fuel selector manifold is approx 250mm (the selector is on the RH baggage wall, where I can see it). Add approx 200mm for full tanks = 450mm which gives a fuel pressure at that point of just 0.49PSI
So very small differences in upper tank pressure due to slightly different venting, prop swirl etc can result in proportionally large differences in fuel pressure from L and R. And that will only get worse as tank levels fall.
Aircraft with floor mounted fuel selectors are marginally better off. In mine that would double the pressure at the selector, but certainly not enough to minimise the effects of unbalanced venting.

On 04/05/2024 at 5:19 PM, Area-51 said:

The only reliable performance procedure determinable to keep AC balanced was to fly on the left wing tank first until half reserve, then switch to right tank until half reserve then back to left, which will be almost full again after 10-15min........

That seems to suggest the return line is delivering at a very high rate.
I believe Skippydiesel did a fair bit of work recently with his return line orifice, and may be able to give us some rates from the various sizes he tried.

As for uneven feed, I am told all aircraft suffer from this to some degree. I have been able to reduce this on my Savannah by doctoring the angle of the ends of the tank breather pipes. But if I was building again I would look at some means of cross-porting the upper tanks, with a single breather, as Cessna do. Having said that, I have seen some odd fluidics in industrial settings, where separate flows are siamesed together: sometimes the flow from one input would take over entirely, excluding flow from the other, though admittedly this was usually in much higher flow situations than an aircraft fuel system.

Assuming you want accurate weights (and in my view you'd be nuts not to) it starts with certifying or calibrating the scales. I checked mine with a range of certified test weights at a local industrial breadmaking business.
After that you can either raise and lower a wheel onto the scales (I used a small hydraulic jack) with the other two wheels packed up (I put a strop across to prevent the UC spreading).......
Or you can roll the aircraft onto the scales, which is not as simple as it sounds unless you have nice big pads for the other two wheels and a good sized lead-in pad for the scales. In theory at least this gets you away from the problem of the main UC spreading and putting side load on the scales. I believe this is how it is normally done.

However you do it, you need to take multiple weighings and they should deliver very consistent results. If that is not happening, something is wrong with your setup.

 

Further experiment and correction to above:
Weighed self on flat, then weighed again with scales flat but leaning shoulder on slippery wall: this is closer to the Savannah situation, where the weight is on the wheel, but there may also be side thrust as the UC spreads.

In this situation, the scales over-weigh.

In both the above scenarios, the scales tolerated a small amount of tilt or lean without over or underweighing. How much probably depends on the design and construction of the particular set of scales.

Conducted  minor experiment with digital scales:

Weighed self on the flat, then placed scales on rigid board, chocked up at one side so scales are no longer hortizontal, and weighed self again.
As the board is tilted up, the scales progressively underweigh.
So unless something is done to ensure no lateral load on the scales, the scales will underweigh.
Which could explain some of the unlikely low weights reported in other threads.

In the case of the Savannah, if lifting and lowering the main UC wheels as I did for successive weighings, that means either preventing the UC from spreading when the wheel comes down, or arranging for the scales to move sideways, as Turboplanner did above. Or rolling on, provided that can be done smoothly.

There is a Statement of Compliance in the very front of my build manual, with various details including MTOW of 1320lb. But that form applies to my specific kit and serial number, it's not generic.

Lukeh, do you have the Pilot Operating Handbook that comes with the kit?

Mine is Rev 5, Revision 05.12.2014 and on Page 24/44 it states MTOW of 600Kg (while noting that local regulations may limit flights to lower value).

Thanks Neil_S. It's been pointed out to me that a similar thread was run here some years ago, but it delivered a surprising scattering of results.
Having said that, weighing can have it's challenges, and I'm of the opinion that unless you can do multiple weighings with almost exactly the same result, something is wrong with the weighing process.
We do know that lowering main UC wheels onto scales doesn't work well, as the UC then spreads and the scales don't respond well to that sideways force. I got round that by putting a strop across the lower UC (then subtracting the strop weight when I got finished). That gave me excellent repeatability.

Rolling on does sound like an excellent alternative, but in practice it needs fairly long and wide ramps and pads that will stay put as the aircraft is manhandled. And again the aircraft has to be moved without inducing any UC spread or flex.

Some headscratching locally over Savannah S empty (no fuel, brand new ) weights, as taken at the initial Weight & Balance.

My S, with standard steam gauges, long range tanks, extended baggage, carpet, adjustable seats and Condor tires (next size up from standard) came in at 314.8Kilos
 

I'd be interested to know numbers from other builders/owners.

Thanks!

Hi Kogg, nice looking machine.

When ICP altered their design by removing the slats and adding VGs, they also altered the profile of the leading edge of the wing. However, it's not clear what difference the change of wing profile made.
Your best source of information for your aircraft would be JG, who pioneered the slats-to-Vgs conversion on that model and conducted a great deal of testing. He flies the same aircraft as you, with slats removed and VGs added, and I don't think he changed his wing. His website is Stolspeed and is a goldmine of information. Suggest you contact him, see if he is open to a conversation:

https://www.stolspeed.com/

I'm a bit puzzled that you say 'im buffeting and beginning to stall power off with no flaps at 60 mph.' I fly a Savannah S, the POH gives a flaps up stall speed of  30 to 35 kts depending on loading, and I know it cruises quite happily at 45kts.
I note you are flying pretty much at Max All Up Weight and it could be interesting to know what your Weight and Balance is.

Gary, I don't have a pic of mine, but here is a detail from the pics the then agent (since retired) sent me.
I think he made the closer kits locally. He was responsible for a number of innovations, and also completed many kit builds.
You can see how the rod is tapered on the outboard side at the end, both rods are like that. As mentioned, I also found it helpful to bend the very tip of the rod inboard a bit.
I also looked at his pics to try and see if they also used the standard door front latch. It looks as though they didn't, but certainly the over-centre action of that latch will pull the front centre of the door in snug.

Gary Nelson, neat job of the door closers!

On mine, the rear rod goes into a hole  in the fuselage frame, outboard of the extruded angle there. The hole is reinforced by a little SS plate, held by 2 rivnuts, with slotted holes to allow some adjustment.
And the rod ends are not points, but shaved off to a point at a gradual angle on the outboard side so that they pull the door in as the rods move to the closed position.  I found the door closed more readily if I bent the tips so as to give an easier lead-in.