M20C Tommy Posted June 28, 2020 Report Share Posted June 28, 2020 I need some assistance on this question. I have a 1965 M20C Mark 21. This is my 1st Mooney and 1st complex. I've been trying to fly the plane by the numbers in the POH and I'm getting drastically low speeds. Take off and climb seems to be by the book but a little less with climb out 115 mph at 650 FPM. Cruise is where is gets interesting. I level off and keep the same settings for a few minutes to stabilize then adjust my settings. Mixture is leaned out RPM set to 2400 at 17 MP at 9500 feet and I'm flying at 135 MPH. Not the 175 MPH in the POH. I played with the settings and went down to 2200 RPM, 2300 RPM, and tested the variety of MP setting in the POH and was getting the same low numbers. The last Annual said all 4 cylinders had between 74 and 78 so I dont think it's a compression issues. Anything is possible. Also my fuel selector worked like butter for a few flights and now its stuck on the left tank. Is there a way to free it up or am I stuck buying a new fuel selector? I sprayed it with corrosion x to see if that will loosen it up. Quote Link to comment Share on other sites More sharing options...
RLCarter Posted June 28, 2020 Report Share Posted June 28, 2020 Is the 135 Indicated? Quote Link to comment Share on other sites More sharing options...
M20C Tommy Posted June 28, 2020 Author Report Share Posted June 28, 2020 Yes, 135 MPH on the air speed indicator. Quote Link to comment Share on other sites More sharing options...
The Other Red Baron Posted June 28, 2020 Report Share Posted June 28, 2020 In my E manual the cruise and range charts are in True airspeed, not indicated, which would explain the difference in speed you are expecting vs what you are reading off the airspeed indicator. 1 Quote Link to comment Share on other sites More sharing options...
jaylw314 Posted June 28, 2020 Report Share Posted June 28, 2020 15 minutes ago, M20C Tommy said: I level off and keep the same settings for a few minutes to stabilize then adjust my settings. Mixture is leaned out RPM set to 2400 at 17 MP at 9500 feet and I'm flying at 135 MPH. Not the 175 MPH in the POH. 17" of MP? That doesn't sound like a cruise throttle setting? That's like 45% power? Quote Link to comment Share on other sites More sharing options...
RLCarter Posted June 28, 2020 Report Share Posted June 28, 2020 4 minutes ago, M20C Tommy said: Yes, 135 MPH on the air speed indicator. The 175 in the POH is “True Airspeed” Quote Link to comment Share on other sites More sharing options...
Ross Taylor Posted June 28, 2020 Report Share Posted June 28, 2020 At 9500 feet you are running WOT (wide open throttle) right? And you’re only seeing 17 inches MP? Just clarifying...that’s low. Quote Link to comment Share on other sites More sharing options...
M20C Tommy Posted June 28, 2020 Author Report Share Posted June 28, 2020 WOT was giving me 19MP. I retarded to 17 since there wasnt much of a change in speed and I needed to conserve some fuel when my fuel selector got stuck. Quote Link to comment Share on other sites More sharing options...
RLCarter Posted June 28, 2020 Report Share Posted June 28, 2020 My charts are in 2500ft increments yours should be the same, just remember to correct indicated for temp & altitude The 10,000ft chart on my E @ 1950rpm & 16.9” is 38% (75 BHP) 2500rpm & 21” is 69% (138 BHP) TAS=181mph @ gross (2575lbs) Quote Link to comment Share on other sites More sharing options...
MikeOH Posted June 28, 2020 Report Share Posted June 28, 2020 Was your fuel selector operating smoothly from left to right and SUDDENLY got stuck? Or, has it just slowly become stiffer until you can't move it? If it happened suddenly, I'd be very concerned as something, that you don't know what, has broken. You might end up with a completely blocked selector! Personally, I'd want to get that figured out before flying again. As for your speed at 9500 feet you really need to correct for density altitude to obtain TAS from IAS. Quote Link to comment Share on other sites More sharing options...
smwash02 Posted June 28, 2020 Report Share Posted June 28, 2020 I attached the POH performance table for 10,000 MSL from my '66C. You said you were doing 135MPH indicated at 9500MSL. I estimated using 30.00 inHg and 15C which gives a TAS of 161MPH. You said this was at 17" and 2400RPM. Book speed is 146MPH, so you're doing pretty well. Quote Link to comment Share on other sites More sharing options...
carusoam Posted June 28, 2020 Report Share Posted June 28, 2020 Tommy, Are you ready to get started? I had the honor of owning the worlds crumbiest M20C... MS can save you from experiencing much heart ache... Broken tank selector valve’s need to get fixed quick... Lasar can help with all the parts required... or sell you an OH’d valve... Don’t wait... stuck on one tank is bad... stuck between tanks is infinitely worse... Are you familiar with Lasar? What POH are you using for book numbers... 65Cs got OMs..? Fortunately, the 77 M20C POH is best for your plane... and a recent copy can be found in the download section around here... Plan on getting some transition training... there is plenty missing from the experience you are asking about... I don’t think CorrosionX has ever been used as a lubricant, or any means to loosen something up... even if it is corroded... Have you talked with a mechanic at all? Always have a good one you can ask questions to.... Welcome aboard! Best regards, -a- 1 Quote Link to comment Share on other sites More sharing options...
Janat83 Posted June 28, 2020 Report Share Posted June 28, 2020 135 mph in the airspeed indicator is what I usually get on my 68 m20c, it's around 165 mph when correcting to altitude/temp, performance in the poh is measured in TAS, not IAS, check your GS and you'll see you're doing much faster than 135mph,if the airplane can't achieve speed in the poh then it might be engine not producing enough power and cylender compressions has nothing to do with engine health, I'd recomend like what other Moonics said to get a transition training in your new airplane. Quote Link to comment Share on other sites More sharing options...
M20C Tommy Posted June 28, 2020 Author Report Share Posted June 28, 2020 5 hours ago, MikeOH said: Was your fuel selector operating smoothly from left to right and SUDDENLY got stuck? Or, has it just slowly become stiffer until you can't move it? If it happened suddenly, I'd be very concerned as something, that you don't know what, has broken. You might end up with a completely blocked selector! Personally, I'd want to get that figured out before flying again. As for your speed at 9500 feet you really need to correct for density altitude to obtain TAS from IAS. It worked smoothly and then got stuck. That would make sense because when I went to pick the plane up, it had some water in the left wing and the sump drain hardly dripped. The A&P pulled the drain plug and replaced it since it was rusty on the inside... It flew fine the 1st 2 flights with 4 hour legs, swapping the tanks every hour. Quote Link to comment Share on other sites More sharing options...
M20C Tommy Posted June 28, 2020 Author Report Share Posted June 28, 2020 5 hours ago, carusoam said: Tommy, Are you ready to get started? I had the honor of owning the worlds crumbiest M20C... MS can save you from experiencing much heart ache... Broken tank selector valve’s need to get fixed quick... Lasar can help with all the parts required... or sell you an OH’d valve... Don’t wait... stuck on one tank is bad... stuck between tanks is infinitely worse... Are you familiar with Lasar? What POH are you using for book numbers... 65Cs got OMs..? Fortunately, the 77 M20C POH is best for your plane... and a recent copy can be found in the download section around here... Plan on getting some transition training... there is plenty missing from the experience you are asking about... I don’t think CorrosionX has ever been used as a lubricant, or any means to loosen something up... even if it is corroded... Have you talked with a mechanic at all? Always have a good one you can ask questions to.... Welcome aboard! Best regards, -a- I have seen the name Lasar many times in regards to Mooney but have yet to get that far. I'm using a 1966 M20C Mark 21 POH. I'll check out the 77 POH! I met some people while I was at Don Maxwell who live close by me. I'll set something up. I have a company that specializes in high end doors and windows where most of the windows I work on cost around the price of my plane lol. The go to lubricant by the manufacturer is corrosion x and we use it for corrosion resistance. Its the red can. Much appreciated for all the help in such a short period of time! This really is a cool space. Quote Link to comment Share on other sites More sharing options...
M20C Tommy Posted June 28, 2020 Author Report Share Posted June 28, 2020 2 hours ago, Janat83 said: 135 mph in the airspeed indicator is what I usually get on my 68 m20c, it's around 165 mph when correcting to altitude/temp, performance in the poh is measured in TAS, not IAS, check your GS and you'll see you're doing much faster than 135mph,if the airplane can't achieve speed in the poh then it might be engine not producing enough power and cylender compressions has nothing to do with engine health, I'd recomend like what other Moonics said to get a transition training in your new airplane. Thank you! Solid Panel! Twin G5s is great. Quote Link to comment Share on other sites More sharing options...
Shiny moose Posted June 28, 2020 Report Share Posted June 28, 2020 (edited) If you want just a simple rule of thumb for IAS to TAS just use a multiplyer of 2% per 1000 feet, not perfect but for our altitudes it will get you close enough . Using your exapmle of 135 IAS at 9500 ft would be 135 X (9.5 X 2) or 19% so 135X 1.19 = 160 TAS Edited June 28, 2020 by Shiny moose 1 Quote Link to comment Share on other sites More sharing options...
M20C Tommy Posted June 28, 2020 Author Report Share Posted June 28, 2020 20 minutes ago, Shiny moose said: If you want just a simple rule of thumb for IAS to TAS just use a multiplyer of 2% per 1000 feet, not perfect but for our altitudes it will get you close enough . Using your exapmle of 135 IAS at 9500 ft would be 135 X (9.5 X 2) or 19% so 135X 1.19 = 160 TAS That's simple quick math! Thank you for your help Quote Link to comment Share on other sites More sharing options...
Hank Posted June 28, 2020 Report Share Posted June 28, 2020 58 minutes ago, Shiny moose said: If you want just a simple rule of thumb for IAS to TAS just use a multiplyer of 2% per 1000 feet, not perfect but for our altitudes it will get you close enough . Using your exapmle of 135 IAS at 9500 ft would be 135 X (9.5 X 2) or 19% so 135X 1.19 = 160 TAS @M20C Tommy, another piece of quick math for setting power is the Key Number approach. Using the nice big numbers on your MP gauge and tach: MP + RPM = 46 is good for our Cs and keeps us away from power and heat issues. At 9500 msl, my C usually has 20" MP, and I like 2500. Before leaning, I reduce throttle until the MP needle wiggles, then lean to peak and richen up. Like this, my indicated air speed (IAS) is usually 140-145 mph depending on temperature and barometer setting. As stated above, 9500 msl is 19% too slow, but I find it easier to take 10%, double it then subtract 1%; multiplying by 1.19 works well on the ground with a calculator, but not in my head at 140 knots . . . . 10% of 140 is 14, so 20% is 28 mph, less 1% which is 1.4, so 140 + 28 -1-1/2 = 166 (rounding up all fractions). If I'm indicating 144, then 144 + 29 - 1-1/2 = 171 mph. Our Cs are quite remarkable! Quote Link to comment Share on other sites More sharing options...
Bob - S50 Posted June 28, 2020 Report Share Posted June 28, 2020 1 hour ago, Shiny moose said: If you want just a simple rule of thumb for IAS to TAS just use a multiplyer of 2% per 1000 feet, not perfect but for our altitudes it will get you close enough . Using your exapmle of 135 IAS at 9500 ft would be 135 X (9.5 X 2) or 19% so 135X 1.19 = 160 TAS Depending on how much you like doing math in your head, 1.5%/1000' is actually closer. So 9500 (close to 10) is about 15%. 15% of 135 is 13.5+ about 7. That's about which equals about 20 or 21 MPH. That would make it about 155 TAS. Quote Link to comment Share on other sites More sharing options...
ShuRugal Posted June 28, 2020 Report Share Posted June 28, 2020 Yes, 135 MPH on the air speed indicator. Um. You do remember from your pilot training that the airspeed indicator only shows true airspeed at sea level on a standard day, right?At 9500', your ASI is gonna be way below true. The numbers in the book are TAS, not IAS. Quote Link to comment Share on other sites More sharing options...
Shiny moose Posted June 29, 2020 Report Share Posted June 29, 2020 Or just go buy or find your old E6B flight computer (I still keep and use one in the Airplane). Not the battery powered one. Use the altitude window and match it with your actual OAT, find your TAS over your IAS, makes those long flights more funner 4 Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.