F

fstringham7a

Well Known Member
RE:Ain't Life Great Part II....BLUE KNOB

Hi ALL

I am back from the big island and had a great time........but.......now back to the 1001 details to finish up my RV7A......Working on all the various fiberglass parts in anticipation of painting it SOON................Will be moving it to the hanger, hopefully by the end of May or first of June. Now to the next very important process....flight prep and transition training.

I have a very good friend that is a CFII that will do much of the training in his 182 and then I will spend a number of hours in a 150 practicing those all important fly it on the runway landings/nose high instead of my getter close and slow and Flare................Then I will be off for the all important RV transition training.

Now for the questions????????I have only a few hours in planes with constant speed props and always in the company of a CFI.....I understand the theory of the throttle/props/mixture but would like more detail or advice in the run up/take off/cruise/approach/and landing phases of an aircraft that has that extra blue knob..............

Thanks in advance...........
 
Cliff notes...

At runup ramp stand on the brakes and add power to 1900-2000 rpm - cycle blue knob full out and back in once - listen for drastic change in pitch.
Blue knob full in for takeoff and climb.
Set MP at 25" w/black knob. Set prop rpm at 2500 for cruise w/blue knob. Lean as needed.
In the break slowly power back - then slowly push in blue knob. Land.

There are variations but this covers 95%. You'll find after about ten minutes that it's nothing to get worried over.

best,
doug
 
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Yup

Not too much to learn..

I usually unwind the blue knob to 2600 if its an extended climb and unwind the mixture knob to keep the CHTs at 350 to 375..This is ROP.

Get to altitude (if its high leave the throttle all the way in..If its low pull the throttle back to 24" MP) and unwind the blue knob to 2400...You are now running at 24 squared...Sometimes I let this got down to 2350 but it doesn't seem to pick up any more speed in cruise so 2400 seems a good number..

Then I yank the mixture till the engine splutters and feed it back in till it just runs smooth..This is about 75F LOP...Then I fine tune the mixture which in my case works out to be about 7.5GPH at 24 squared.

Pretty simple.

Frank
 
Thanks guys for the info.........I will enjoy the study guides suggested for reading.

CJ I didnt know that your suggested readings had a picture of my highly modified RV and Props Controller.....:rolleyes: I have spent alot of time in the right seat of my first CFI's Skywagon on wheels....he just couldn't find enough water near SGU to justify keeping the floats on....but he has put it down on some pretty ruggeded/short/not very straight back country strips. (Grand Glutch Mine near SGU comes to mind as one of these fun in and out rides.......



Frank1 keep those videos coming as they keep me motivated...

Doug your simple explanation even allowed this slow MBA brain to understand...:D

Brad thanks for the FAA info on the subject.............

Frank @ SGU and 1L8.....RV7A not really that modified......last 1001 details!!!!
 
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Frank, I am glad you liked it!

When the Skywagon is equipped with the 3-bladed water prop, (most of the time) the tips go subsonic and the noise is very annoying to the neighbors (and it even wears on me a bit too) so our procedure is to get the plane up on the step and bring the vernier back a couple of twists to quiet things down.

It sure is a lotta fun!

Read Deakin's other articles (see embedded hyperlink) on Manifold Pressure as well. It really gives you something to think about.

:) CJ
 
My procedure

I start with the prop fine, max(in). On run-up I cycle three times. When I open the throttle for take off it goes all the way open and stays there until I'm approaching the airport to land. After 100 feet or so I pull the prop back to 2450 for noise control and for travel that's where it stays until I'm returning to land and I've pulled back the throttle enough that it now controls the RPM like a fixed pitch prop then I push in the blue knob to be ready for a go around if needed. I have backed out the governor limit screw and re-safety wired it so maximum RPM is limited by the governor structure at 2,730 rpm for racing. for Airventure Cup and other races I run max RPM wide open throttle and lean for best speed in the vicinity of 1300 F on the hottest cylinder EGT (the CHTs are in the 300s). I have flown it in the last 3 AirVenture Cup races from Dayton to Oshkosh, two 100+ mile races at Taylor Texas, the Memphis 100, the Wichita 300 and the Texoma 125 with no problem. All Cylinders are in the mid 70/80 range after 413 hours. I may try to jack up the RPM for more power in the future. I have a standard (not bush) LASAR ignition system. I use Shell 15w/50 oil with the anti-wear included in the product.

Bob Axsom
 
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