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SE-VUD, amateur-built Zenith 650 aircraft engine, aircraft and a short flight from ESGO Vårgårda
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John A. Urban
I hope you saw comment in the 650 forum.In my working days, in the automotive world, I have seen what heat, altitude and poor fuel-quality can do with performance. In your area with altitude of 5100ft you will probably loose about 15% torque already at runway, at 20C, with a normal aspirated engine. 185 Nm instead of 220Nm. I measure 1700N traction force at 300 ft, and I guess you get 1450N at 5100ft. But I think the high temperature can make even more damage. I understand 40C is possible in summer. I have seen a big loss of torque in my aircraft, when temperature rise from 0 to 25C. Automobile engines have normally a much higher compression ratio, and knock sensors are used to control ignition timing. So if you use 85-87 octane fuel in a hot area, power will be reduced a lot. I have seen up to 50%, even at sea level. Aircraft engines with low comp. and fixed low ignition and higher octane rating are not that sensitive. But sure you need a longer take off. I use 250-300m from full power to 50ft alt, at a hard track. Count on 500m in your area. By the way my MTOW are 450kg instead of 600Kg. I use MOGAS 95 oct. RON (similar to US 91 oct AKI). In my country, Sweden, there is no runway above 2000ft, and temperature above 30C is rare. But the latest week we have seen up to 32. A bigger radiator than the Rotax is necessary. The D-motor have 2x more displacement than Rotax 912. And it is also 100% watercooled. Rotax only cylinderheads. If I should start from zero today, I would try with a bigger automobile radiator under the floor, like Viking installations use to have. Keep coolant temp below 95C, a new recommendation from D-motor.
What was the final empty weight? Please keep posting about this aircraft as you compile more data. Especially performance numbers. Speed, fuel burn rates and climb at gross weight. I'm at 5,100 feet, or 1,554 meters field altitude here in Nevada. I really like the simplicity of the D-Motor. If possible, I'd like to stick with the smaller of the two like you did. Mainly because it's so much lighter than the six cylinder. I just don't know if it will have the performance I will need, at gross weight, to get off the ground without eating up a lot of real estate, at this high of an altitude.
Thanks! They have some nice looking instruments.
Kanadria Nesis III 8,4 inch. I dont know if it is available in US. Company located in Slovenia.
Amazing, we all look forward to more flight reports!
Also, can you tell us what EFIS you are using? It looks great.
Great to hear that you like this engine. So far, I am very satisfied. A simple engine that acts just as an automobile engine. Only turn the key and it starts, a lambda controlled fuelinjection always gives the right air/fuelratio. I have measured 1050 ft/min at low 2500 rpm. Max is 3000. I have not tried max speed yet, but by mistake I have been at 195 km/h. I have only 2,5 hours flight time yet, so max speed measurements comes later.
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