skippydiesel

Carb ice in a Rotax 912?- flew my last Rotax powered aircraft for about 10 years. Cone filters (no airbox or carb heat) and never knowingly had icing. Under cowl temperatures a fairly consistent 10 C above ambient. New aircraft with Rotax 912ULS with homemade/designed air box AND liquid anti ice/heated collar. So far about 8 months flying - no ice - under cowl temps around 25 C above ambient.

Yeah! All true - thought I was coming into some money and wanted to see if I could maximise the performance on my Zephyr. Money was an illusion and I crashed the Zephyr. Insurance got me an almost completed Sonex Legacy/Rotax 912 ULS with Airmaster 3 blade constant speed. Dont get me wrong the Armaster is great but I am not convinced that the Sonex would not be as/almost as, good without it. Short TO role, under 100m on grass (without trying for a short field) climb out (still working on it) but I think about 2000ft/min at 80 Knots full fuel. Cruise at WOT 5450 rpm 147 knots (152 true) @ 3500ft - I usually tootle about at 130 Knots indicated, 5100-5200 rpm, for a fuel burn of 15 L/hr (still working on the fuel consumption). All of which is great BUT I have a mate with a Sonex B/912ULS & he is getting about the same cruise speed, probably a bit longer TO role & less Climb Out but he wouldn't have an extra (say) 6 KG on the nose and would still have around $13K in his pocket. There is no doubt that a constant speed will improve the performance envelope, but the cost effectiveness in these small, relativly low hp, aircraft is ????????

I thought I got great service from my two blade, ground adjustable Fitti Sport on my last aircraft. Lots of interest in the E Prop range - talk to Kyle. Their CS is a light as many ground adjusts.

$31-$40 DEPENDING ON WHERE YOU PURCHASE

untitled (rotaxowner.com)

Maaat! I don't know about your CO detector - mines a Caravan/Marine type, Velcro mounted in the cockpit, with its own batteries, that last for at least two years if not more. Has a nice big digital display, memory/history, so you can check back for Max CO ppm & light/sound alarm, stays on 24/7 - leave it with its batteries soooooooo simple!😈

Much will depend on your ground clearance - Airmaster CS will do you a 3 or 2 blade but recomend a 3 blade for most Rotax applications. I would seriously question, the cost effectiveness of, fitting of a CS prop to any RAA class aircraft - if you configure a ground adjustable for your preferred operations (cruise for you) you will come close to the same cruise speed, as a CS, without the added cost, complexity & weight I see you have "Purchasing Topaz" under your nom de plume. Is this the aircraft you want to put a CS on? Is there more than one model? Do they come in nose/tailwheel - all information for the Forums Brains Trust, I suggest you give all details, for best advice.

Your comment reinforces the gut feeling, that I have had, all along, about the RAA move to higher max weight - how exactly does this change make RAA so attractive that GA pilots , that they will rush to join?????😈.

I will have to go back & check what I wrote some many moths back but from geriatric memory Rotax recomend a Mikuni #35 Restrictor Jet. My original return fuel rate was 7.6L/hr at about 3 psi I later installed a small jet which did not solve my problems at the time (low fuel pressure during climb out). Later again a read the Vans document below - sounded similar to my problem - went out & purchased a new higher capacity Boost pump - worried about overpressure - reinstalled the #35 restrictor jet - all good! I also redesigned/plumbed my three tank fuel system, so I can choose (which I do) to use the tank with the return flow for all ops (previously couldn't). https://www.vansaircraft.com/wp-content/uploads/2018/12/Notification-2018-07-12.pdf The RV-12 recommended Facet Cube, PN 40135, delivers Pressure Max/Min 7.0-4.0 psi and 32GPH (US) . This is well above Rotax recommended Max 4.5 psi https://facet-purolator.com/specifications/ Mikuni web - https://mikunioz.com/shop/bs3096-pilot-jet-bleed-type-for-cv-carbs/?v=13b249c5dfa9 I used the VM22 style (that was originally fitted) but on reflection the N151.067 might have been a better bet. Jet fitted in to the end of one of the spigot tube push on fittings. In short the return line restrictor jet selected will be governed by the fuel system configuration, Boost & Mechanical pump performance

"That was an issue with the kit (they supply 27mm!)" Kit???? 27MM ID???? Gates Au will supply: - a molded 90 degree bend, in diffrent "Arm" length options PN 03-0010 ID 25.4mm, Arm 1 125mm, Arm 2 125mm ($10-12) PN 03-0011 ID 25.4mm, Arm 1 300mm, Arm 2 300mm ($15-37) Multi Fit Coolant Hose with two bends, a 135 & 90 degree PN01-007 ID 25mm Length 550 ($?) Then there is 25 mm connectors Straight PN28606 ($20) Elbow PN28626 ($19) Tee PN28638 ($51) Unfortunatly the above connector must be purchased in a minimum of 2/bag From "Started a Spare Parts List" - I have used the above - nice fit on the Rotax radiator spigots (25mm). You will almost certainly have to use a connector, the Gates ones are a very secure fit.

No gravity flow in most low wings - pump all the way. In a 912ULS installation, I would question the sanity of anyone relying on gravity feed - particularly when it comes to fuel vaporization mitigation.

Hi Danny - I hear you Note that the coolant (17mm ID) from Floods is 85.80/m + delivery. Gates Silicone (16mm ID) $16 -$28.50/m + delivery from UK or Australia about $38/m + delivery (some are offering free) Then there is all that good stuff from Mackay ( should be cheaper again). Personally, if I can shave $500 or so off an estimated $1,500+ (from RoTAX) 5 year rubber replacement, using good quality materials, I will be very happy. Convenience can come at quite a cost - as always your choice😈

I agree with you Nev however many get confused by the relationship between flow & pressure. In a 912 ULS (fitted to a Pipistrel) no fuel pressure is required to run the engine. However to get the fuel from wherever it is being stored (tank), pressure (gravity & or pump) will be required to deliver the fuel. Depending on the height above/below delivery point (carb float bowl) that the supply is, plus the effects of tube/hose ID and length (frictional losses) will determine how much pressure is required to deliver the appropriate volume/flow, to the engine at full power (max demand). Note: Other effects will be pipe bend radius/valve types & number/ filters types / return line jetting. Hope I have covered all/most of the issues.

To the best of my understanding, the current price per meter from Floods: Coolant Hose Part No 922250: $0.78/cm + GST + $85.80/m ( you will need over 2m depending on installation) Formed 90 degree hose Part No 9222192: $47.33 +GST = $52.063 (one of) Oil Hose Part No 956394: $1.02/cm + GST = $112.2 / m (you will probably need about 3m depending on installation) So around the $560-$600 + delivery

"Friction losses are significant in small tubes over any distance, an example most people can understand as the water pressure at the tap comes out screaming but at the end of the 10 m hose it is nowhere near the same pressure, this my friends is friction loss." Me thinks you are confusing flow & pressure - The pressure should remain constant, while the flow is reduced, due to such factors as friction. In small (carburettor) aircraft we monitor the health of the fuel supply system in pressure (kph, psi, Bar) but actually use the fuel in volume (L/hr). All the pressure in the World may not deliver sufficient volume of fuel for your engine to run.

More info on 16mm (5/8) silicon hose - https://vansairforce.net/threads/5-year-rubber-alternatives.186607/

ll you Rotax drivers ; Check this out - https://vansairforce.net/threads/5-year-rubber-alternatives.186607/ Seems that 5/8 (16mm)ID silicon is being sued quite often onto 17 mm OD spigots

Just found a Pommy supplier of Gates Heater Hose 17mm ID, 24mm OD , Part No. HTH017 $16.00/m (+ delivery)

Well there you go - must of missed that. Will get a price and compare with RoTax AU supplied 17mm ID coolant hose. Thanks Found it! https://www.shop.flylight.co.uk/engine-service-parts-72-c.asp Straight 17 mm ID silicone hose $28.50 per M (will need 3M) 90 Elbow 17 mm ID silicone hose $23.75 each (will need one on standard configuration) Subtotal $109.25 Above as a kit is now $151.98 but includes hose clamps which can be purchased locally (ie a saving) Then the cruncher DELIVERY ?? - in common with the USA, Pommy delivery is almost exclusively courier and very costly? (RoTAX Au starting to look like it may be competitive - will get a price during the week)

Thanks Blue - my question is not about using silicon hose as such but about using 5/8" (16mm) ID hose pushed onto 17mm OD spigot/barb. (I assume your 25mm ID is going on to 25mm OD spigot). From earlier post: My questions are; Will the Gates silicon 5/8" hose fit, without damage, on to a 17mm OD spigot/barb? Are there other factors that I should consider? The reason for my question is the lack of straight (as in not shape molded) 17 mm ID coolant hose, on the open market - You can purchase it from RoTAX at an exorbitant price.

Does the lack of response mean that no one has tried using silicone coolant hose ????

So you agree, the entry criteria is likely to focus on equipment carried ( ie com, transponder, etc) rather than build type.

Mackay are astonishing in their range of products. This will get you their universal products range (25 mm ID radiator hose being of most interest to Rotax drivers) https://www.mackayrubber.com.au/hoseproducts https://www.mackayrubber.com.au/_files/ugd/478d7d_f2637e84ee494d8ca160b52dd68de25c.pdf https://www.mackayrubber.com.au/_files/ugd/17eaaa_9774ebec8334488e94706a9951ddfacd.pdf

Update: It seems that Mackay (Australian manufacturer of automotive hoses, amongst other things) make a wide range of 17 mm ID molded hoses - the above question is now moot but I would would still be intersted in the experience of anyone fitting silicone hose to a larger OD spigot.

I stand to be corrected - Dont see the logic in that - GA experimental (home built/modified) are not so restricted.