skippydiesel

"When I'm cruising I have to adjust my propeller to a high pitch to prevent the engine running over maximum revs. " Small but important point to avoid any confusions - Propeller pitch is expressed as Coarse to Fine. Terms relative to the angle of attack (like a wing) to the airflow. What you seem to have described is Corsening the pitch to slow the engine rpm at a given power setting. "What I don't understand is where my best/least fuel consumption comes from when matching RPM to Manifold Pressure while maintaining cruising speed." In my aircraft (912ULS/Constant Speed prop) best speed/economy is in the region of 5000 - 5200 rpm. I usually Cruise at 5000 rpm, 25" Hg , 2500 ft ASL for a an average (whole of flight)fuel flow of about 14.25L/hr @ 130 knots true. Your aircraft will deliver a diffrent True airspeed at similar settings. "Lets say I want to keep the Rotax 912ULS spinning at 5000 revs while getting my best economical cruise speed. Do I control this with manifold pressure?" Manifold pressure will change with density altitude. With an acurate graph/power chart for your aircraft/engine/prop combination, you can adjust power accordingly. I find the following easier; On my last aircraft I had a reasonably accurate fuel flow meter, so was able to adjust power at any altitude to fuel flow. My current aircrafts fuel flow meter is nowhere near as precise, so I fly to True airspeed - probably offends the real pilots but works for me.😈

Rotax do publish the manifold pressure/expected fuel flow/ altitude/ engine rpm charts; Join Rotax Owners Forum for all the Manuals/Service letters/etc https://www.rotax-owner.com/en/rotax-forum I strongly advise you read the Rotax 912 ULS Operators Manual file:///C:/Users/User/Downloads/OM_912%20Series_Ed4_Rev2%20(3).pdf Some downloads that may interest you; https://legacy.rotaxowner.com/si_tb_info/serviceletter/sl-912-016-r1.pdf https://aquila-aviation.de/wp-content/uploads/2021/06/SL_912_016R2_914_014R2_Rotax_Notes_engine_handling.pdf A couple of excerpts; Note: The figures given are nominal ie will differ due to many factors eg airframe😈

It should be a "copper crush washer". Yes any correctly sized sump style washer, can be substitutes eg soft aluminium, solid copper, neoprene, etc. The above washers can be purchase from almost any auto accessory supply store. I purchased my "stash" from Floods at the same time that I purchased oil filters. I get x3 washers to filters, as I use the same crush washer on the magnet and I practise 50 hr oil changes, filter at 100 hrs.😈

"........ this likely because you are capturing this data on the ground. Because rotary wing aerodynamics. If you set cruise pitch/RPM setting on the ground, sitting statically, the angle of attack on the blade would be far higher than in fine pitch, something it would not be encountering in flight because of the big differences in induced flow velocity (thence the resultant relative wind), therefore the data would not be representative. The angle of attack for your prop blade running at fine pitch on the ground is likely not too far removed from what it would be in flight at your cruise RPM/pitch. This is why the prop pitch setting is minimal on the ground and in takeoff and is advanced for your in-flight regimes (ie climbout, cruise, descent)- so it is operating at its design factor of merit (your prop efficiency) as much as possible...and also the most likely explanation as to why they want flat pitch on the ground. If you were doing this in flight, then there would be an appropriate regime for this to capture the data...in your case, the OEM specified pitch & RPM setting for a given airspeed & pressure altitude. This video explains, visually, what I am talking about:"

Well I aspire to fly across the Nation, Sydney - Perth/return, at least once. Further afield if that test flight workes out. I got out of GA because I couldn't fill a four seater, let alone a 6. All of your nominated airfields will be visited, plus many others, with a flight plan of 15L/hr ULP @ 130 knots true. 😈

So far I have taken the following from the responses to this question; Prop manufacturer sees no reason for not analysing vibration at Cruise rpm & Cruise pitch. Doing a vibration test in the air, may result in a better vibration analysis. I do not think I am any the wiser, as to why the prop manufacturer specifies having the prop at Fine Pitch, for this test. 😈

What about using a paint cone filter?😈

For out technical Forum 😈 https://www.google.com/search?q="Turbo+Encabulator"&rlz=1C1GGRV_enAU751AU751&oq="Turbo+Encabulator"+&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIHCAEQABiABDIHCAIQABiABDIHCAMQABiABDIHCAQQABiABDIHCAUQABiABDIHCAYQABiABDIHCAcQABiABDIHCAgQABiABDIHCAkQABiABNIBCTMzMjJqMGoxNagCCLACAfEFTZ_cH81_qsjxBU2f3B_Nf6rI&sourceid=chrome&ie=UTF-8#fpstate=ive&vld=cid:85f99d6b,vid:Ac7G7xOG2Ag,st:0

I'm amazed, all you guys with your cheepo, non aircarft certified, oil filter can cutter haven't YET been attacked by the aircraft certified, lest you fall out of the sky, only way to go, chaps.😈

My prop manufacturer has finally responded to my question their recommended fine pitch V my exploratory coarse pitch @ Cruise rpm. "Wrt your question about testing the prop at 5000rpm in MAN vs AUTO: Yes, 5000rpm (or otherwise your normal cruise RPM) is the most commonly attained RPM during flight. With the constant speed prop in auto/cruise - this is often attained by a reduced engine power setting and the propeller at the fine pitch limit (for flight economy)- the fine pitch limit is the most commonly reached pitch setting in flight. Your suggestion to alternatively test balance in manual mode at 5000rpm (by adjusting fine/coarse) and at a higher power setting is also acceptable. The reason we recommend the first way is simply because automatic operation of the propeller is considered as 'normal' operation i.e. manual mode is not typically used besides during start up checks." Do you think they have answered why they recomend fine pitch @ 5000 rpm in their Manual?😈

Back researching Bluetooth headset adapters; As far as I can Google, there are only two basic designs - The two standard AA x2 battery battery types, that will transmit iPad, (traffic, music, etc) phone, (in /out calling), etc?? $240-$400 Au. About 3 offerings available. The Six Aviation, rechargeable/USB powered that will only transmit iPad (or similar) audio (traffic, music) $92 + Au I would rather not have to carry additional AA batteries. No interest in inflight music or phone calls. The Six would seem to be the only option, that is unless you know of something else?? Please do not recomend a Bluetooth capable headset - I have four perfectly good headsets (one ANR) it seem crazy not to try and enhance what I have, rather than purchasing another unit. The Six has mixed reviews, from terrific to total failure???😈

Hi Garath, Yes they are a new /unused /in box with screws etc - My research suggests the (negotiable) price I am asking. NOTE: Most of the ones you will Google are not the posative lock type as mine is😈

I am not an electronics person: In my limited experince, an aircraft grade (need not be certified) antena give far better transmit/receive performance than a dipole. You can mount under or top of fuselage - If you go under (ventral), between or close to main undercarriage, often selected for ground clearance and an antenna with a "crick" in the end, usually selected. Its good idea to mount the antenna, as far as practical from engine, to minimise the chance of electrical interference. Ground plane not required if fuselage metal. If fuselage composite or fabric over frame - Ground plane can be made of any metal. In aircraft weight & space considerations may dictate material. Copper foil, aluminium most commonly used. A cross pattern works just as well as a solid sheet . Size of ground plane dicted by frequency (I think) and internal space in aircraft - this can be easily researched or someone on the Forum will recomende.. In my last (composite) aircraft I used: Ordinary aluminium "Flat Bar" 20 x 1.6 mm as the longitudinal strip (screwed down) Builder ductile aluminium flashing for the cross fuselage strip. The flashing is easy to smooth to the shape of the hull. I glassed the flashing to the hull, going slightly vertical on each tip. Where the two aluminium strips crossed, I made a "sandwich" from aluminium sheet (probably 2mm thick) with locating holes for the (ventral) antenna base. I did use dielectric grease between the connecting surfaces for good conduction & inhibit corrosion. Electrical connection to "ground" return very important - make sure its excellent. Can't recall the dimension - do remeber that the flat bar was the correct length but the flashing was a bit short, due to fuselage shape & dimensions. After installation I did SWR the antenna for best performance. The radios transmit/receive was terrific.😈

Between weather & domestic responsibilities, it's taken me quite a while to almost complete my aircrafts 200hr service . Just yesterday I was able to test my Six Aviation Bluetooth adapter again. My thanks to BurnieM for this suggestion; The answer is an emphatic NO! it does not transmit music from my iPad, so I guess it wont give me traffic warning either. I will be contacting the supplier & Six Aviation later today to see what they can do for me.😈

That's a problem that can be overcome with a ladder or better still a "cherry picker". The convenience of the hot foot type product is that it doesn't require fixing like spikes and should be relativly easy to apply/use. Be sure to take a scrapper & stiff brush up with you to remove accumulated droppings & dust. We used hot foot at work - we were having issues with pigeons & miner birds in covered walkways. From unreliable memory one treatment lasted many years.😈

Hot air leaving the cowl is not important. Heat around the ignition modules & the voltage regulator (VR) is. Put your thermocouples in these areas. If possible either mount your VR in a known cool area or consider fitting dedicated outside air duct onto the VR. You should also consider insulating all fuel lines /fittings in the engine bay, to minimise the chance of fuel vaporization/vapour lock. Shield the underside of the carbys from exhaust pipe radiant heat. You can make shielding using ductile aluminium flashing, supplied by any good hardware/building supplier (even Bunnings Aerospace). Fix in place with double wrap safety wire on exhaust and or cable ties on carbys (Alternatively purchase Rotax carby drip trays - they do little if anything about drops from the carbys but do act as good heat shields, better looking as well.). I "Silastic" /glue exhaust wrap to one side of the flashing for extra insulation and safety wire it around a hose where it is in close proximity to the exhaust system . If you are fitting an airbox (Rotax or other) consider ducting outside air in, more efficient combustion/power. The down side of this is greater chance of carby icing - need carby heat or heated inlet manifold rings.😈

Back to "Hotfoot" on all potential roosting sites.😈

https://www.flygas.info/supercharger-rotax-91214/😈

How about some photos of the "supercharger" installation😈

Please advise what product(s) you believe give the best anti-seize protection, when screwing stainless steel (SS) into aluminium and when screwing SS into SS??

One thing for sure about this debate - we all have diffrent understandings of the rules. It's also possible that the (RAA) rules are not being strictly observed.😈

Could be - my figures were for illustration purposes only and reflect common practise by many commercial users of 912's. One of my local fling schools has people on a waiting list for their TBO engines.😈

Marty_d "I'll have to experiment with baffles and more targeted direction of airflow." Check out a few diffrent Rotax 9 instalatons. I think you will find that few, if any, have baffles (as in an air cooled engine). Possibly oversimplifying: Rotax oil/coolant heat exchangers facilitate locating these in a good air flow. Inlet air ports need not be large however exit ait is all important. Your target undercowl temperature should be about + 10C above ambient or lower. 😈

I have no idea what Wal charges to zero time a Rotax 912 BUT if its $13K which you can probably get (if not more) for the TBO engine, this is money that can be put towards a new engine. The new engine will be up to speed with all Rotax upgrades/changes and have no reused (suspect?) components ie if the change over cost is say $5K why not purchase the new. TBO Rotax 9 engines regularity appear in the classifieds - most are from flight schools and are between 1 - 2 K hrs, well sort after by home builders looking for a cost effective power plant.😈

My limited understanding; From an administrative/legal perspective - If you zero time an engine , it is effectively a new engine, so it's not surprising the (certified/factory built) aircraft can continue to be used for hire/reward. Note: for zero time the engine must be rebuilt by a authorised service provider and there must be documentation confirming its rebirth, as an almost new engine. While it may be possible to zero time a Rotax, I am lead to believe, it is more cost effective to sell the TBO engine (for use in an experimental aircraft) and purchase a new replacement for your factory/certified aircraft.t😈