IBob

Did a few numbers, and now trying to make sense of them: To lift 1Kg 1m takes 9.8joules. 20L petrol = approx 15Kg So to lift 20L of petrol 2m theoretically takes 29.4joules. All very well in theory. A single AA cell supposedly packs 9,000joules. (and a single alkaline D cell something like 72,000joules) So no problem, right? Flip now to spec of Easyflow battery powered pump listed earlier in this thread. This uses 4 x AA cells, and is sold as a transfer pump (not a lifting pump). And claims to transfer 400L on one set of batteries. That number doesn't seem unreasonable to me. But given the disparity between that and the theoretical numbers, there must be huge inefficiencies and losses somewhere. Or maybe what's left of my brain just shut down for Christmas.......(

My thought exactly........)

The spec says the batteries are good for 400L I think.

Now that looks to be a step in the right direction! I note that it is shown transferring fuel between 2 containers at approx the same level. The spec makes no mention as to how it would perform if pumping 'uphill'. Garfly, do you use yours with the can next to the filling point, or are you pumping from ground up to the wing? And if so, how well does it go, and how long do the batteries last?

One of the main jump centres in the UK had one in the late'70s. I was part of a load of ballast used to demonstrate it to visiting military on a very windy day, so we didn't jump, but went up then came down near vertical in the thing, all jammed against the back of the pilot's seat. The military didn't buy, but we enjoyed the ride. Evidently they are quite heavy on the controls and tiring for the pilot to operate, certainly as a jump ship. That one came to a sticky end when a pilot inadvertently selected beta pitch shortly after takeoff.....(

Pmccarthy I fuel using a 20L container with one of those bendy corrugated spouts. I lift the full container onto the top of the steps and swipe the bottom edge with my hands to make sure it has not picked up any dirt or grit. I then lift the container onto the wing and rest it, tilted on the skin over the main spar. Positioning it to allow max eventual tilt, I bend over the nozzle to point at the funnel and tilt further to start the flow, increasing the tilt until the nozzle is well into the funnel. This allows me to transfer approx. 10L to one tank, and with no spillage. I then repeat the setup at the other tank, but in this case I have to lift the tank (instead of resting it tilted on the wing) to get enough tilt. I usually brace an elbow over the mainspar to steady my hold, and I do sometimes get a small amount of splash onto the wing when the flow first starts. Once in position and filling, I have no other spillage. I'm not particularly strong in shoulders or arms, initially I thought I would have a lot more trouble with this than I now do (though I have certainly had the occasional larger splash). I find the bendy nozzle is a big help. I use a cheap plastic funnel about 140mm dia. I'm sure the small Mr Funnel would be more challenging for that second tank. I wonder if the 20L container might almost be easier to handle in some ways?

AUTO CARB HEAT: The Savannah XL and S take air in to the airbox via a NACA scoop on the top of the cowling. The airbox has a temperature probe, and I noticed that in a hard climb, the airbox temperature would rise. The reason was that the increased angle of attack altered the airflow through and round the cowling with warm undercowl air being taken at the 20-25mm gap between the NACA scoop fibreglass and the airbox inlet, instead of cold air from the NACA scoop. This was easily fixed by extending the airbox inlet with an aluminium tube, held in place with a hose clamp. I left a gap of approx 3mm to allow drainage in the event of rain while parked. The extension is marked with a black felt pen line at the RH end of the airbox. (The scat tube is warm air from the muffler for those times when you do actually want carb heat).

Ah, gotcha. The Savannah 'carb heat' just takes air from over the muffler into the airbox, so is divorced from other systems and not at risk of complicating them.

Hi Brendan, we had a club Tecnam make a forced landing here some time ago. Very experienced pilot, long descent to finals, I think, started running horribly rough so he set it down. Started and ran no problems thereafter, no fault found and subsequently returned faultlessly to club use, so high likelihood it was icing. The aircraft I mentioned on short finals was a Savannah, they take air from outside the cowl, the pilot described it as being like the engine wanted to leave the aircraft. Selecting carb heat in my Savannah certainly results in reduced power, I wouldn't call it negligible. As for the kiss principal, you are in no way complicating anything by having heating available, as most of the time you won't be using it. So I don't see the advantage of kiss here. What it is is an option that's very nice to have on the day that your engine starts to cough and run rough...

What RFguy said. If you have the option, there is no way I would leave it out, Danny. I've had icing cruising just below low cloud level in mild weather (figures!) and I know of another member here had icing on finals, which is exactly when you don't want it. FWIW the Sav has an airbox temp sensor and if in doubt, I now follow the advice of the second example above, by keeping the airbox temp not less than 20'C.

That is a low figure, but i'll certainly buy it. If the prop pitch is perhaps a bit on the fine end of the climb/cruise compromise and and it's flown quietly.

BrendAn, I believe Rotax recently lifted their initial warmup recommendation to 2200RPM, and certainly mine has always felt 'happier' at that initially. Once warmed, I pull it back to 2000RPM, I don't usually go below that. As for warming up, it depends what you are referring to: while the head coolant temperatures in mine come up fairly promptly, the oil temp is much slower. This seems to be usual, and some fit a thermostatic bypass to the oil radiator, with varying results as the oil tank still requires a fair bit of warming.

I'm still not biting, Glen. Shortly you'll set off that guy who always claims to be flying round at vast speeds on 12L/hr, while entirely ignoring the fact that his aircraft is light, and his engine is not working very hard. You can't make any headway with this stuff. It's like the GA vs ulight attitude you run into occasionally.......or all the sh*t people eternally tell themselves about where the 3rd wheel is......(

I'm confident in what I write about fitting running and maintaining the 912 (though always more to learn there too). I know nothing about the 0-200 other than what I can dredge up online. I don't know enough to be running comparisons.

Yes. I'm not thinking straight there............(

I saw the 0-200 quoted at 22L/hr at 75% but perhaps that figure was wrong?

Thanks RFGuy, yes that post is 9 years old, what you say seems to sum it up as we stand now. To which I would add the estimated NZ$27,000 fuels saving that is 5L per hr over 2000hrs. Mark is certainly making a nice job of the alternative throttle linkage. And quite possibly others face challenges that I don't, and so will benefit from that.

And........that was met by a deafening silence.......) Here is someone operates both an 0-200 and 912: https://www.rotax-owner.com/en/912-914-technical-questions/4678-o-200-vs-rotax-912-costs Second post down: "As for balancing the carbs, most of the the problems I've run into are not with the carbs but with improperly installed or poorly maintained throttle cable systems. I check my carb balance at every annual but haven't had to adjust them in two years." As for the 0-200 vs 912 question, he loves them both, but wonders if the 912 may require overhaul sooner.

continued................ The rest has been very straightforward: Pretty much the only synchronisation tool you have is adjusting the relative length of those cables. So I did this: 1. First checked idle stop and idle jet settings as per the LM manual. This is quick and easy, and as noted the idle jet settings were only approximate, so worth doing. 2. With everything in place, I cut and fitted a stop block at the firewall: when the throttles are fully closed, the spare central lever on the throttle bar bottoms on this block. This prevents the carb throttle arms, which are light in construction, from being flexed or bent, upsetting adjustment, if the throttles are closed firmly (as you do when stopping the engine). 3. I reasoned that since the engine spends much of it's time at 75% power or above, this was where I wanted best synchronisation. So I push the throttle knob to fully open, this puts some slack in the cables. I then gradually close the throttle, watching the two throttle arms to see them both start to move off their stops simultaneously. This required several small cable adjustments in the first 40hrs, but in the 200hrs since, while I run this simple check regularly, I have not had to touch it. Surprisingly also, given the different cable lengths, the fully closed appears to be pretty much perfectly synchronised too. And that's it. I inspect all this carefully at service intervals, and lubricate the cables with light oil (I'm not sure about that, but it seems to be working okay in this environment.)

Hi Yenn, a certain amount of it was in understanding what was in the kit, and working with that for best results, so bear with me if I go there first: The Savannah has a throttle bar across the width of the firewall, with arms connected to L and R throttle knobs, and with a pair of arms or quadrants side by side at the LH end that operate a pair of bowden cables. The short LH cable goes to the LH carb, the longer RH cable to the RH carb. I would guess this is a fairly common setup. Note that this is very positive when closing the throttle and the cables are being pulled, but when opening the throttle the cables are not pushed: they rely on the carb throttle arm springs to draw the cables. So for this to work well there can be no binding in the cables. Accordingly, I went to some trouble to ensure that all parts of this setup were well aligned and free moving. Also in the case of the RH cable, I was very careful to install it with sweeping curves so as to minimise cable friction. And for the LH cable I ensured there was a small but sufficient amount of curve in the outer to allow the engine to move on the mounts. I was greatly helped in all this by a series of pics supplied by the then Australia agent, Reg Brost, which proved to be gold when it came to making a tidy engine instal. Here is a pic of the cables coming off the throttle bar, they are the lower cables: And a pic of the engine bay showing the routing of the cables to the carbs: Note I have since seen a factory build where they do an even nicer job of curving that RH carb cable: they fit a little cable fastening near the top LH side of the airbox front, which makes for an even softer curve. continued below..............

Hardly, Nev: I responded to each of the items you raised, including acknowledging the matter of carb floats. You want more detail????

Let's see: 1. Balancing the carbs: adjusted the cables as they bedded in to synchronise movement at full throttle. No further adjustment required for last 150+hrs. 2. Bowl breather tube: piped to airbox downstream of air filter, job done. 3. Carb floats. Yep they definitely had issues there, I have replaced one set as directed and supplied FOC. 4. Carb to manifold rubbers. Swap 'em out when the time comes, or maybe you don't believe in periodic maintenance? 5. Gearbox service and sprag clutch. I expect no issues at all as I use unleaded fuel as recommended, and the more recent ignition units give excellent starting. 6. Throttle linkage? Mine works fine. 7. Not sure what your problem is with the alternator. Is there a problem with the alternator? 8. Oil return system: it works fine. Surely that is a the measure of a good machine: not all the theory, but how well does it work??? 9. Starting and stopping technique: simple. Okay Nev, you don't LIKE the 912, it offends your sensibilities, I guess. You're entitled to that. FWIW I'm ambivalent about the 0-200.

I'm not following you there, Facthunter. The 912 as I know it doesn't require any fiddling at all. I just open the throttle, the prop is pitched about right and I put the carb heat on as required. Otherwise, it takes care of itself in all modes of flight and requires no fiddling at all, in flight or on the ground. I do blank off a bit of radiator in winter, to get the oil temp up. And I take an interest in how it all works.

Facthunter, I don't disagree with your theory, in any respect. But I do read much of what is written here, and what I don't see is any undue pattern of weakness or failure for the 912. It is what it is: not the 'perfect' engine, not ideal for everything and everyone. But for the slot it does fill it seems to me to function remarkably well, and especially so since the designers grasped the nettle of liquid cooled heads and high engine speed, securing many benefits, but also complicating the design.

I'm sure you're right Nev. But I'm left with the thought that, for an engine with so many design shortcomings.....it works remarkably well....)