IBob

888z nobody here is trying to sell you anything. You asked for information to help you choose, people are responding by pointing you to information that may be useful. Part of that is understanding why there was a general move away from LE slats to vortex generators. And the Stolspeed owner was foremost in that and there are very good studies on his website. With the engine size and fuel consumption there is no magic : x fuel in gives you y hp/kw out. The 80hp engine will give you an aircraft that requires a longer takeoff run, climbs slower, and cruises slower. It's that simple. Regarding the Savannahs, there is some confusion with the naming, which seems to vary a bit from country to country. 1. Here in NZ I do not think we have any of the original models with the LE slats. 2. We have the next model, which is called the VG because they removed the slats and added the vortex generators From there, ICP remodelled the fuselage in 2 stages: 3. We have the model after the VG which is called the XL or VGXL. This has the remodelled front end, larger cockpit etc, but still has the flat sided rear fuselage. 4. And we have the model after that which is called the S. This has the rear fuselage remodelled and rounded. Finally, so far as i know, nobody imports the BRM aircraft here.

888z here is a link to an excellent site, where the owner has done a great deal of work on the question of slats vs vortex generators. I recommend reading up on this, if you have not already done so: https://www.stolspeed.com/slats-v-s-vgs As for fuel economy: I think I'd be right to say pretty much nobody down this way fits an 80HP engine. Part of the reason for this is that the fuel consumption is only a part of the ongoing cost of owning and running an aircraft, and the extra $$$ on fuel and consumption is well spent in terms of range and performance. The ULS is also a better proposition when it comes to resale.

I heard that this or something like it was found at the back of an RAF hangar in the '60s, and that one of the more accomplished (but more reckless) ATC cadets looped it on a dare.......(

Skippy, I would think principal factors would be technique, prop weight, and size of power wiring/distance to battery. Note also some aircraft do not have a negative battery cable, but rely on hull ground, which can be less than ideal: if the engine does not turn over briskly on the starter, something needs to be done about it. After that, I would suspect the setup/gap of the trigger coils, especially if one of them was a bit tight, which could lead to a premature spark advance on that part of the circuitry. As described elsewhere, they need to be gapped to spec. using non-ferrous feeler gauges, as ferrous gauges will stick to the magnets and feel just like a good fit even when they are not. It's a good idea also to check the setting using a go/no go combination of the required gap then the next size up.

According to my Heavy Maint Manual, the old flywheel is 4deg before TDC, the new is 3deg before TDC, and they both then shift to fully advanced at 26deg before TDC. Part of the problem with the original setup is that each ignition module has two trigger coils and each of those trigger circuits is doing it's own thing, trying to measure trigger pulse amplitude to decide when to flip from ignition fully retarded to ignition fully advanced. So unless all four of those trigger coils are gapped and performing exactly identical in output, it's possible to have part of the ignition still firing retarded and part of it advanced. I'm kinda amazed they went into production with this. What the so called soft-start does is override all that and force all 4 trigger circuits to the fully retarded state, holding them there until several seconds after the starter is released, by which time the engine is up to reasonable speed, so all 4 trigger circuits then cut promptly to fully advanced. I can only speak from my own experience, but in 250+hrs I have never had a rough or dirty start. And while the shift from retarded to advanced is quite evident when it happens, my engine does not run rough during the start. Understanding how the choke mechanism operates is also important in all this. I am also told, by a very experienced instructor who also runs his own older 912 with a Bolly prop, that the (older system) club Tecnams with their heavier props are a different challenge again when trying to ensure clean starts.

Mark, the new flywheel shifts the retarded ignition point by 1degree.....is that right? I would have thought the soft start modules would work fine, regardless of flywheel type???

All good comments, Skippy. I have no idea if they have an on condition program for the 912 in Spain, something that 888z may need to look into. My thought with the soft start is that it is well worth having, the difference in starts in huge. The fact is that the older retard system (still present in the new system, but essentially overridden) is very poor and makes for some messy starts even with battery and wiring etc all in good order. And poor starts are hard on this engine. While the soft start can certainly be retrofitted, most owners do not shell out for 2 new ignition modules to do so.

PS: some S models come with long range fuel tanks, 4 instead of 2, and that is the standard arrangement in Australia and NZ. If you are going to make longer trips this can make a real difference: the 912 runs on mogas, which is not always available and may require multiple trips to town, while away, in order to refuel.

Hi 888z and congratulations! Some things to be aware of for starters: Some early models of the 912 were vulnerable to crankcase fretting ($$$$$). Early 912s have a 1500hrs TBO, later models have a 2000hr TBO. Later 912s have a much improved ignition retard for starting. Poor starting on earlier 912 could lead to sprag clutch damage ($$$). So, I'd be looking for a 2000hr TBO engine, recent enough to have the new ignition soft start setup. Also, the 912 has a 5year rubber replacement requirement, including the fuel pump and all the engine hoses. There is some cost in this, so when is it due? Rotax have an excellent website with a user's forum where you can read up on all this. Be aware also that the Savannah has comprehensive 1000hr checks to be carried out on the airframe. Again there is some cost, so when is that due? Apart from that, I would be looking at the general condition of the aircraft, how it has been cared for. And I would be going through the maintenance records to see that it has been kept maintained and if there is any damage history. I would most strongly recommend that you get an experienced aviator and/or maintanance person to check over the aircraft and paperwork with you. As for VG vs S model: Most VGs will have the older engines: (see above) The S is definitely more roomy and that is an improvement. (It also has more baggage space if it has the extended baggage mod, though baggage is still limited to 20Kg). The VG probably has the edge on the S when it comes to STOL, though the S is still very good. The S is a bit faster in the cruise, though we're not sure why. Also, these are lightly constructed aircraft and will have a shorter working life than older GA aircraft. So, generally speaking, I would go for the S unless your main aim is to win STOL comps. Finally, 80 vs 100hp: I cannot comment on fuel consumption. But I think you will appreciate the additional performance of the 100hp engine, and especially if you will be doing STOL work and/or will be flying with a passenger (loading makes a big difference). Happy hunting and let us know how you go!

My understanding is that ICP were originally agents for a S American derivative of the Zenith 701. They then began to manufacture their own version. So, maybe what you have there is a S American model? Either that or it has been damaged and someone has made replacements. It's interesting also that the aircraft is painted but the struts are not. See attached pics for ICP strut attachment. AN bolts down the sides, A4 rivets across the top. It is also AN bolted at front and back inside the undercarriage tunnel. So the main undercarriage would have to come off to remove the attachment. Given the critical function of the assembly and the use of nonstandard bolts, I think I would be removing them to verify that they are free of cracks throughout. This would include the bolted flanges inside the tunnel. I would also be checking all wing attachments for correct bolts. The AD you refer to is for the front strut attachment at the wing main spar (not at the fuselage).

The extended nut in the first pic was maybe used to mount a camera or similar? The bolts should be secured with the correct AN locknuts, not Loctite. The current maintenance manual calls for quote: white grease, Renolit Z2 for hinges/bushings/bearings/rotating parts. It also calls for Bardahl High Speed chain spray grease for rotating parts and general additional lubrication. I would definitely be inspecting the strut attachment brackets, as suggested by Pluesssy (above). I would also be checking if the bolts are of the correct type, as suggested by Kenlsa (above). I believe they should all be AN hex head, with matching washers and locknuts, not socket head, and that includes the bolts through the struts. It would be interesting to know why the socket head bolts have been used??? It is this stuff that holds the wings on........................... No comment on the crack, trying to figure out where on the aircraft this is and what it does? Camlocks are from Aircraft Spruce, get the dimensions and search online for the correct part #. Grommets are any auto/hardware supply.

I don't know, Nev. Quite possibly the airflow over a pitot head at 14 deg is less likely to be disrupted at, say, 60kts, than at 40kts or 30kts? And I expect the head could be designed to reduce the breakdown or disruption of airflow: mine is a very crude open ended pipe, not the polished bullet heads you see on real aeroplanes...............)

Blueadventures, similar effect by the sounds of it, and I would guess of more or less relevance depending upon the aircraft and the phase of flight. In mine, for the full flaps landing that I use a lot, you have to hold the nose up and the speed down on finals if you want a reasonably short landing. And especially if lightly loaded, which I usually am. It took me a while to transition to what the aircraft will do in this configuration, to the out of balance controls, to more rudder and less or no aileron. What I read of high A of A in STOL machines was that the IAS could drop out entirely. I think having reliable ASI helped me practise that phase of flight, at height initially, then in landings.

Hi Marty. During my build I came across quite a few references to the ASI dropping out on high angle of attack approaches. And I came across either a reference or a pic of JG's VG where the pitot was cocked down a bit to help prevent this. I think I may have contacted him to ask about it at the time. And I then put a small bend in my pitot to cock it downwards also.......I cannot now recall how much, something like 7 or 8deg would make sense. I fly my approaches heads up but with constant momentary references to the ASI until just a bit short of flare, when I'm fully heads up. I have never seen my ASI decay or drop out at high A of A. In normal cruise etc my ASI still reads accurately. I'm not promoting this, and I don't think JG was either. But it may be worth considering?

Not a UFO story, but a what-I-am-seeing-can't-be-happening event that fairly boggled my mind at the time: Mid 70's I was maintaining Sperry Univac mainframe gear, including twinned CSPs (Communications and Symbiont Processors) on one site. These were quite large free standing L shaped cabinets that handled all the comms plus miscellaneous local peripherals, and were equipped with rows of large white indicator lights and rocker switches on an upper maintenance panel. The entire system was still under development, but had run faultlessly for 6months, I was in the workshop some distance away when I heard one of the programmers yelling my name. Sticking my head out the door what I saw were all the indicator lights, which normally flickered with a pleasing dull pearly light, were blazing white as though I was looking into a furnace. I ran for the thing, and as I ran I yelled 'TURN IT OFF!!!!' To which the programmer yelled back 'I HAVE, I HAVE' while repeatedly pushing the DC and AC off buttons. Actually we may have screamed.....I'm pretty sure my voice went up an octave. These machines all had multiple rack mounted power supplies delivering various voltages, with power cabled to junctions under the hollow floor. Arriving at the machine, I tore open the front covers and wiped my hands down all power supplies, knocking all the front mounted internal breakers off. Jumped back......and the lights were still all blazing. At which point, for just a moment, I literally was not believing my eyes. Hard to describe, it was quite a jolt. For the rest: I ran and got the floor sucker, we now had smoke as well and I was tearing up the floor tiles looking for the underfloor connections to pull them. Comedy note at this point was provided by the suite manager, who danced round my hole in the floor with a fire extinguisher yelling 'SHOULD I HIT IT, SHOULD I HIT IT?' as I flung 2' square steel reinforced tiles this way and that. I had not located the the underfloor feeds when it finally quite suddenly all went off: something of a relief as I wasn't looking forward to pulling live feeds. The entire system was down, (though most of the smoke was at the CSPs and the Modem Room). So we (techs) all went for a cup of coffee. And after about 20minutes our chief tech walked down and put his finger precisely on the problem. Any old techs here care to take a shot at what it was? (I should have said that the CSPs were part of a much larger 2 x 2 multi-cabinet mainframe system distributed over an entire floor of a large building.)

I know Gary Larson had a lot of fun with them:

Looking great, Mark........and looks to be really gratifying work too....)

Yes Aro, but this is where I get stuck: if the rotating part is wobbling, due to imbalance, that means the 'heavy' side is rotating on a (slightly) larger radius than the light side. Would you then not expect the beads/mercury also to flow to that heavy side? Or, at best, is the angular acceleration identical at those two points...in any case, what I am getting at is what are the forces acting on the beads/mercury to cause them to distribute?

I would very much like to see an explanation as to how/why the mercury/shot would distribute themselves so as to provide balance. I'm not saying it doesn't happen, I'm saying I would like to understand how. And so far I have not come across an explanation, just assertions that it does.

I still can't see it.......(

Curious............

Link not working, Danny.

I was at a Queensland dropzone years ago when the pilot put down, crawled around underneath for a bit, then called it for the day and flew away. Can't remember for the life of me what the aircraft was...8 or 10 place, I think....but a load had gone down near an ag strip (round canopies,little drive, bad spot) so he set down there, they repacked, loaded up. On takeoff he rotated over a sheep that nipped out from behind the fert bin, resulting in large woolly dents in the belly of the aircraft.........(

Yes...but was it a Cessna???