cruise settings?

[Gilt]

My 63C...WOT/2500 rpm... if the tach is correct, I had it over hauled last year but I hear they indicate 50-100 low. May go to Sears and get one of those laser tach things and check it. Speed...went up yesterday at 6500' WOT/2500 50deg rop...149 knots via GPS.

[Hank]

One day, I really need to do the three-course speed check. The 134 mph was Indicated; quick finger-counting tells me that at 10K, add 20% to indicated, or 134 + 13.4 + 13.4 = 134 + 27 = 161 mph, which is in line with what I remember from the POH, even allowing for my 3-bladed speed brake. The memory stick with the photo and POH is downstairs, a couple hundred yards away, and I don't remember the groundspeed on the GPS; when I saw the photo I was looking for indicated airspeed numbers and was happy that the shot had the complete 6-pack and the 430 in it.

[N33GG]

Quote: Hank

Larry--

I have a 70-model C, and my long-term average fuel burn is very glose to 9.0 gph. My "standard practice" varies according to the charts in my POH [OK, already--it actually says "Owner's Manual" on the yellowing cover].

Low altitude:  23"/2300

Medium alt: 23-24"/2400 [keep it below 75% so I can lean it back]

Optimum alt:  WOT/2500

I recently saw a picture at 10,000 msl, WOT, leaned to 50º rich [should have been leaner], with indicated airspeed of 134 mph. Don't recall the outside temp, but it was last fall coming home from the Carolinas. Don't forget the temperature correction factor on the performance chart, either. +10ºF, -1% power; -10ºF, +1% power. Don't go leaning above 75% total power.

I very STRONGLY recommend taking the MAPA PPP to learn the ins and outs of flying your Mooney. If memory serves correctly, there's a formula they publish for our engine [O-360-A1D] something like this:

MP  +  RPM  =  47 for 75% power, MP  +  RPM  =  46 for 65% power, MP  +  RPM  =  45 for 55% power. The first one is correct, but I'll need to look up the other two to verify that they aren't 70% and 65%.

Your fuel burn appears much too high, even if you were loaded to max.

 

[Hank]

George--

23"/2300 is where I make short trips, usually 3000 or 3500 msl. If I'm going more than ~50 nm, I climb higher and adjust per the book to less than 75%. The numbers above are typical values, but I have to watch temps in the winter and remember that my power is likely 1-2% higher than the table. I'm trying to learn to lean more at higher altitudes when WOT produces less power--at 60-65% power, is it necessary to run 50º rich, or would peak EGT be acceptable? Some carbs run LOP, but not mine.

If I'm crossing the Appalachians, I like at least 7500' VFR or 9000' IFR; both are good for WOT/2500. I've seen steady-state groundspeeds from 104 kts to 183 kts running WOT/2500 over the mountains, but indicated airspeed is usually in the mid-130 mph range.

Fly safe, and look for tailwinds!

[Parker_Woodruff]

Quote: OR75

I am a bit confused. What settings do folks use on their J model in cruise at say 8 to 12 thousand ?.

[Jeev]

Quote: OR75

I am a bit confused. What settings do folks use on their J model in cruise at say 8 to 12 thousand ?.

[Alan Fox]

Below 5000 feet I go with 23 inches and 2400 rpm , and this nets me about 10.4 GPH , People that are running 24 24 are burning about 11.5 gph , ( I used to run at 24 24 until I put a JPI in my airplane ) The difference in cruise speed is about 2 knots , definitely not worth the extra 6 dollars an hour for fuel... Above 7000 I run wide open and 2400 with gps ground track about 150 to 155 knots  (the best econ is at 12000 feet )

[Barry]

Quote: Hank

One day, I really need to do the three-course speed check. The 134 mph was Indicated; quick finger-counting tells me that at 10K, add 20% to indicated, or 134 + 13.4 + 13.4 = 134 + 27 = 161 mph, which is in line with what I remember from the POH, even allowing for my 3-bladed speed brake.

[scottfromiowa]

N74795, what are you leaning to?  Peak? 50 LOP? 75LOP? 100LOP?  50ROP? 100ROP?  This to me is the most important part of the equation regarding cruise settings...The red knob ultimately controls speed, temp and fuel burn.  Throttle and Prop are important, but the red knob is the key.  Just curious what setting...beyond just fuel burn you are aiming for. 

I fly 2500RPM and firewall throttle taking whatever MP I get above 2500.  I reduce throttle to 2500 if down lower.  I have mixture full rich in climb, but aggressively lean in cruise to peak and always fly LOP 50-75 degrees.  If I was full rich there would be a massive fuel burn.  By using multi-probe EGT to lean flying 25 squared (or lower down low on MP) or lower (Up high...what ever I get MP) gets me cool cylinders, a smooth running engine, best speed/economy.

I just purchased a fuel flow/HP tool (EI) that I look forward to identifying more accurately (if we ever get some decent flying weather again in Iowa) what my fuel burn is in cruise at different altitudes for my plane.  I bought my plane to go fast in cruise so I will spend the six bucks an hour for a couple of knots.  Finding that combination of cool smooth running engine balanced with fuel flow is what I am trying to achieve.

[KLRDMD]

Quote: Barry

 1 knot is 1.15077945 mph ... So ... if you take 140 kn, and add 14 and 7 you get 161 mph. 134 kn + 13.4 +6.7 = 154.1 mph.

Actually, recently I've read an article that there is a company who is STC'ing an electronic ignition. You run a mag on one side and the electronic on the other. It makes the engine run a lot more smoothly, better power and allows a carbureted engine to run LOP giving a big boost in the MPG figures. It is to be on the market some time this year.

[Hank]

Thanks, Ken. I just remember 2% per 1000' falloff on the airspeed indicator, and if I need "KNOTS" then I use the groundspeed readout on the 430. That's the only place it matters, since it shows distance in nautical miles. Indicated Airspeed in knots is useless when my instruments and books are all in mph.

[KLRDMD]

Quote: Hank

. . . if I need "KNOTS" then I use the groundspeed readout on the 430. That's the only place it matters, since it shows distance in nautical miles. Indicated Airspeed in knots is useless when my instruments and books are all in mph.

[Hank]

ATC has only commented on my speed twice:

1)  Asking me to slow down for sequencing on an IFR training flight, still outside the IAP

2)  Asking a Lear inbound on the ILS behind me to "reduce speed 50 knots, you're behind a Mooney indicating 80" on my IR checkride [i checked AI, 105 mph; GPS readout was 80 knots]. I asked the DE if I should speed up, his answer was "sure, let's see what you can do." So I raised gear & flaps, gave her some throttle and accelerated down the glideslope, slowing down again when I was 2 miles out for a touch-n-go.

The only other speed-related comment was inbound to pick up the DE for my checkride, with a howling tailwind they addressed me as a Baron and asked my intentions. I corrected them with "Mooney" and said "full stop." I'd been practicing there rather often leading up to checkride day. Did I mention that we have no approaches at my home field?

[Steve Dawson]

Actually, recently I've read an article that there is a company who is STC'ing an electronic ignition. You run a mag on one side and the electronic on the other. It makes the engine run a lot more smoothly, better power and allows a carbureted engine to run LOP giving a big boost in the MPG figures. It is to be on the market some time this year

 

Do you know where there's more information on this STC?

Steve

[Steve Dawson]

I see that LASER Electronics has a unit, but has anyone tried this and are there any other manufacturers?

[n6773v]

Electroair has a unit which is supposed to be certified this month.  Their web site is www.electroair.net.  They claim 10 - 15% fuel consumption reduction.

[Barry]

Electroair is the unit I'm familiar with. I believe it was in the EAA SportAviation mag ...

[Alan Fox]

Hey Scott , I generally run about 25 rich of peak just to be on the safe side , (I am not injected)