RFguy

Not sure about the fuel saving calcs. fuel is fuel. I would think because the O200 is a bit happier at lean of peak, the O200 might be lower fuel cost, apples for apples ULP. weight advantage would depend on the aircraft.

Bob, I read through that thread, I would agree a problem for Rotax is the lack of suitably familiar mechanics. and parts are priced to deter rebuilds IMO. They are a little fussy and complex compared to an O200 but that's what you get for the advantages of - weighing 30% less and not ever having to worry about engine temps, and not have a bulk strip if you have a prop strike....and most will go to TBO with just a gearbox overhaul to 1k hours. (ULP) I think Mark's rotax throttle linkage solves the multi throttle cable problem with a nice hammer..

I am seeing around $300/cuM for 32MPa in country NSW.

How much is price in your neck of the woods for 32 MPa concrete /cuM with a batching plant local ?

The concrete on site pour and tilt up is competitive with the steel- (after the steel prices went up). I think there is 15 tons of steel in my steel hangar build proposal . plus roller doors, PA doors, insulation blankets, door hardware. The concrete wins on the labour on big sheds where the steel assembly labour is significant. The concrete is nice for insulation- to a point- hangars are not well sealed as they spend a bit of time with the doors open. The concrete walls , will go to the mean daily temp , most likely. This the concrete actually needs a insulation layer on the outside - that's the best construction for thermal control- just like dumb Brick veneer homes away from the coast - they have the bricks on the wrong side of the wall for thermal control- needs bricks on the inside..... where as the steel building the temp will go up and down like a yoyo, well not so much the slab does a fairly good job of limiting the peak to peak. so add more thermal mass in the form of concrete walls the peak to peak narrows . so at cowra, the tilt up concrete probably goes to about june-july-august about 9 deg C , and peak summer probably a comfortable 24C . The steel though can have a few windows easily popped in for the mezzanine n etc and other areas as things change. certainly they can be poured with the gaps in the tilt up, more complex though.

The rotax is pretty forgiving of misalignment of ... everything... at cruise and WOT settings. It does not however, like idle settings. the inlet manifold is suboptimal, the gearbox doesnt like it. However, that's hardly an operational disadvantage to all the other fine attributes of the engine. I'd suggest warm up oil cooler bypass and water cooler bypass, to limit the warm up idle time where the engine is unhappy. Or a sheet of cardboard..... On warm up, I idle the club rotax at the top end of the rotax permitted warmup RPM , and use a sheet of cardboard on both coolers.

Is the Bristell a CS / IFA prop ?

Unfortunately the council didnt plan the blocks for T hangars , either. ANyway, now can consider the merits of concrete tilt up versus steel.

No, we probably wont read about it and that is the downside of the RA framework. There's plenty of upsides, just depends on how you rate them. I would think, for a rotax, there would be very few combinations that would be problematic, it has a high range of acceptance of MMOI. The prop is well isolated from the torque pulses . However, props in RA are a bit of wild west - not perceived as a significant modification by many . Certainly in any direct drive engine like the Jabiru, that's very much a symbiotic relationship between prop, engine and flywheel. So I am putting this down to a maintenance issue , overspeed , or material failure. (ha! ) . ALthough I dont even know if it lost prop on landing nor before?

I am 2nd on the new 'taxiway'.. club is next door, Trevor is on my right .

At Cowra, there are several hangars new hangars being built , one large one being built right now (I know because I see the DAs , as an adjacent land owner) . there might be a bit of room shortly.

alright you two. stop it.

SKippy what you nned to be concerned with the exit cowl air , is the exit air exiting TOO SLOW. Energy will be required to accelerate cowling exit air up to the flying airspeed, and with the Vsquared parameter in there, it will hurt. So, ensure your cowling exits are not TOO broad/large than optimal . Too large and the velocity (for a given airflow) will be too slow, and that will be drag because the slow cowling exit air needs to be accelerated. Too small - that will reduce airflow/ limit pressure difference between frontal pressure and inside cowl (which is required for cooling to work ) , but may also provide some thrust. So the name of the game is not too large, not too small..

I just dont buy that the prop just fell apart on a rotax UNLESS there was a maintenance issue.

Hi Ian 18x24m, 5.5m to gutter. There is a 25m block width (50m deep). this leaves 25-18 = 7m only for outriggers for doors Preferred option is on site poured and tilt up concrete, but I cant seem to get the proposed contractors mind on the job, the has too many late running jobs right now due to wet and boggy condix. they can do four tracks. short listed shed kit supplier only does two row doors. I have specified that I only need 14.5m open to one side at any one time, so the two track solution is 3.4m outriggers, and 6 x 3m doors . three doors on each track so three are pushed over on two tracks to one side and I get a 15m opening one side. push doors over the other side, I get a 15m opening the other side. Up the middle, that's only 12m opening. But the intention is only two active planes one in each side of the front part of the hangar. airplane projects can go down the back. workshop+mezzanine in the rear half. This is not a 'club hangar', so is purpose built. Ideally, Cowra would have T access hangars. commercial details by PM Glen.

"Better to be quiet and thought a fool, than open your mouth and dispel all doubt." love it. hangar is gettign closer.

I have never seen roos on haul roads on any of those sort of mines. Maybe it's just where I go. nevertheless, a good effort by the pilot to get it onto some unoccupied ground .

Kangaroos on a mine haul road ?????? What ? sorry I dont buy it. Kangaroos generally stay right away from such places.

Hi Bob ..Jab mixture was about right before LCH, now rich. I am led to beleive that all 912 engines have problems with the intake manifold at low gas velocities (idle etc) and that they all tend to foul / rich the front two cylinders with extended low idle , due to intake manifold arrangement. But I dunno, that's what I have heard and read

Bob, all over rich Bings powered engines I have seen are all problems with float bowl vent location OR enrichment not getting fully off, or accidental carb heat. However there is another interesting one I am partially troubleshooting right now, Jabiru engine that was about right, now rich after LCH. Heads instead of 150C , now 100 C, which would have an effect on vapourization/ atomization and combustion. I have bought a Oxygen mixture sensor so I can get a benchmark to understand what's going on- (IE to figure out if its really rich or just low EGT, or a combination thereof) since there would be an effect of both perhaps lower head temps (change to behaviour in the chamber) and also there would be some cooling of the EGTs due to the much cooler heads and headers. -glen

depends if we are talking about Bing carbs, or something else with a genuine restriction.

"When a coolant temperature sensor decides that no choke is needed , the magnet releases and a spring returns the cable to the off position " ha ha like when just airborne ?

Vso 26-30 kts ? and Vne 124 kts wow ! you can get in and out of short strips AND chase the Germans in a vertical dive

I think many of the problems come from seeing the two modules stacked on top of each other. They cook each other .. 10mm of separation would do it.... but airflow is king !

The starting carburettor is quite clever ,Bob. the sytem permits a big gob of fuel first breath and then uses the starting jet. It is an impressive and ingenious piece of engineering.