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Old 09-25-2019, 02:49 PM
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rvbuilder2002 rvbuilder2002 is offline
Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 8,891

Originally Posted by NORM T View Post
Hey guys, my data was just that, data, not a controlled test and obviously not repeatable. I am sorry if my numbers upset people I simply flew it on an early spring day to find my comfort zone regarding engine rpm and fuel burn. The airplane is a 2015 with the 912 ULS that I purchased flying with 18 hrs on the meter, in 2017. Flying with whatever the conditions were that day, autopilot on straight and level, with me and a maybe a half tank of non-ethanol premium mogas, much less than max gross weight, about 3000 ft msl, 2800 agl, noted the Dynon readings for what I believed were steady state for IAS in kts, fuel gph and RPM. The data indicated to me that I could comfortably cruise at about 5200 RPM with best MPG, but above that the fuel economy goes down rapidly. Flying at slower RPM resulted in data that indicated less MPG, but more hours flight time per gallon for just flying around. As for absolute values for airspeed and fuel burn, I can't control them except with throttle setting in level flight, they are whatever they are, and I accept that. I do not know the prop pitch, but I see about 5200 RPM in full power climb at about 80 kts and maybe 1000 fpm. Full power in level flight will rapidly exceed redline RPM. This is when flying near sea level.

I did not intend to stir the pot nor try for bragging rights. I think my RV-12 does what Van says it does. I like it a lot.
I didn?t mean to offend with my post.
I was just trying to point out that a little bit of data that only tells a small piece of a story doesn?t really provide any useful info. I don?t mean to offend again by saying that but it is true. With an adjustable fixed pitch prop., it is possible to set the prop so that a specific performance perameter is fantastic, but all other #?s will be abysmal. I can say from experience from literally hundreds of hrs of flight testing it is not possible to get 127 Kts TAS at 5500 RPM at 5 GPH and still have normal climb performance.
I?m not saying you didn?t see this numbers..... just saying that there has to be some other influences ( you were looking at ground speed instead of TAS, the prop pitch was way off to where climb would be severely effected, etc.).

Point being, the performance #?s posted on the web site are real and valid and we?re attained after hundreds of hours of very detailed flight testing, and if anyone thinks they are getting #?s that are different by very much, it is likely because of an inaccuracy in the data or some adjustment that will be effecting a different perameter in a negative way.
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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