Hey Laurent, I find that it is safer to have less brakes than too much brakes on the Amphibian/catalina. When you come into landing the amphibian touches down soooo slow (34Mph) you usually don't need the brakes to slow her down. When using the brakes to correct bad runway alignment on landing ( or try and save a bad landing) it's best to have less brakes as the avid will swing hard around its vertical axis because the wheelbase is really narrow. Also consider that a hard breaking or full power run with brakes set will lift the tail up in the air and slam the nose onto the ground with good noise, the elevator is not enough to overcome the pitching moment (high thrust line..) Hope that helps
I will take close-up pictures of my ignition module install. Most important is that they don't get too hot from engine or radiators..I also mounted them on rubber vibration mounts . I am surprised there is no info about the angles the engine has to have. My engine has a 1.5deg to the right as viewed from the rear. My catalina has a tendency to turn left (yaw) proportional with power. It flies perfectly straight without power at the same speeds. I did try a tab on the rudder but that did not help
I also made bushings (aluminum) but they go full length inside the rubbers so as to use 1/2in bolts. My rubbers were designed for 5/8 inch... I also had to grind some rubber to make them fit in the engine mount. I have a question for you..is there anything about thrust line/angle for the 912 install??? Keep going, it's a great project you have :)....& send us pictures of your work
Hey, yessss I'd love a copy of the 912 install. Also I want to share my thoughts about 3 bladed vs 2 bladed prop on the catalina. I had the opportunity to try out the same propeller (koolprop/Nrprop scimitar blade shape carbon fibre) in both configurations (2 bladed/70inch and 3 bladed 69inch). On my catalina, the 3 bladed propeller does not allow the wings to be folded...not enough space between the flaperons for the 3rd blade. Performance wise I found the inflight numbers to be VERY close/equal. There was a little gain on initial acceleration for take-off for the 3 bladed / 1/2 to 1 second shorter take off run. I chose the 2 bladed option because: 1. less weight 2. less propeller moment of inertia 3. very small performance difference versus 3 bladed 4. much nicer sound 5. need to fold my wings for storage 6. cheaper Remember, the catalina with a 100Hp is a lot of power for it's weight (750Lbs) & big wings (36ft). Propeller does not make the big change...HP does...and it only needs 28Hp to stay in flight not loosing any altitude!!! Also note that the catalina hits an aerodynamic wall reaching 100Mph no matter how much Hp it's being fed. More Hp equals higher rate of climb and shorter t/off. To give an idea, 4800rpm=86Mph / 5200rpm=92Mph / max power 5700rpm=97Mph flying straight and level
Sorry but the manual I have does not show anything about the 912 installation...only the 582. As you are finishing your catalina I would like to emphasize the need to do everything you can to save weight. Especially in the tail area. The 912 installation is heavier and brings your CG further back than with the 582 engine. When I restored my catalina I removed 40Lbs of weight and now I can fly solo without added weight up front, also mind blowing performance on water. My Catalina weighs 750 empty and has electric gear (450Lbs useful load). It used to be 798 Lbs
Hey jbmaridon I have a 69in 2 bladed propeller. Note that you will have to include about 1 1/2 in clearance between the tip of the prop and the fuselage. From what I know there are only 2 engine mounts provided by avid ... one for the 2 stroke (the 582) and one for the 4 stroke 912. I have never heard of a modified / different 912 engine mount. Your engine should fit between the top 4 mounts and the lower single mount. Today I will measure the distance between the prop shaft centerline to fuselage to confirm.
Welcome...I have a 912 powered cartalina. 69inch Koolprop/Nr prop 2 bladed sabre. Happy to help you ....I am 1Hr from Vancouver/canada. here some pictures for you https://1drv.ms/f/s!AvMw5i-09AkLmURmKBSU8uAlC3IR https://1drv.ms/f/s!AvMw5i-09AkLrBtSxvtsC_MQNeYT https://1drv.ms/f/s!AvMw5i-09AkLmyLHNPdIaLSnwTWe https://1drv.ms/f/s!AvMw5i-09AkLmyLHNPdIaLSnwTWe
Hey, I had a similar learning curve/hardship making my 912 smooth. I solved it doing the same kind of actions you did except one simple one obvious you might have overlooked. The ignition cables...mine looked great/like new. My engine would idle fine but at higher rpm there was one or two wires grounding somewhere.. I went ahead and replaced all the wires (solid core no fancy carbon etc.) and voila my engine run perfect. None of the removed wires had any chafing or visible damage... Also note that before replacing wires I had trimmed the ends going into the spark plug caps and coils...no help My 2 cents
What about your idle speed??? What about starting and shutting down the engine?? In the usual operation RPMs the crossover does not do much.. where it shines is smoother /much lower idle speed, softer starting and shut downs If your engine was running a bit rough before the crossover, it will run the same after the crossover mod...the rough running I found can come from 3 main sources and I found myself searching for 3 months...: 1. air intake rubbers leaking/cracked/porous 2.carb issues....took me two rebuilds to get it right (slider spring length difference/choke valve seal leak/float hight adj./float chamber overflow tube badly positionned in airflow etc..) 3. ignition issues: Pick ups not at the right distance to targets/coil malfunction/coil bad grounding wire connector corrosion/bad ignition wire or chafed wire/spark plug caps/ spark plug electrode gap/ignition module power supply wire intermittent
Hey Chris, I did the mod 2 years ago....my memory is not that good. What I do remember is that before the crossover I always had the rear cylinders overly rich and black and the front cylinders were on the too lean side...that was mostly solved with the crossover. My understanding is that the intakes don't have the same length from carb to front/rear cylinders making it very difficult to even out mixture, especially at lower rpms.