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Just how fast would a C model fly, if a C model could fly fast?


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Yeah I'm very curious to how these guys swear they are getting 155-160 true in the carb'd 180hp models. An eighteen to twenty-three knot INCREASE in TAS by doing some mods and rigging seems quite extraordinary. I mean a 13-17% increase in TAS for under $20k in mods is actually not bad IF it was guaranteed...

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Trying to get a little more out of my C. Working on fitting the new induction system on mine so it fits under the new more aerodynamic cowling. It’s a tight fit and here’s attempt number 4 to get the air filter to fit the baffling. 
David

9069787A-A6C3-4BB1-9F7F-8546BBC72254.jpeg

61C33CF0-9987-488C-8565-18C4D541C2B2.jpeg

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1 hour ago, Raptor05121 said:

My D model with a 3-blade constantly trues out 143-147KTAS depending on mixture setting and weight. Not sure how accurate my ASI is, however.

Handbook says 4 MPH difference between IAS and CAS at most cruise settings.  Each time I have flown a 3 or 4 heading test, it appears my ASI is 2 or 3 knots optimistic. I had a stock '65 C almost 40 years ago and it cruised 142-144 knots.  That was way before GPS and I could not tell that was incorrect.

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2 hours ago, Sabremech said:

Trying to get a little more out of my C. Working on fitting the new induction system on mine so it fits under the new more aerodynamic cowling. It’s a tight fit and here’s attempt number 4 to get the air filter to fit the baffling. 
David

9069787A-A6C3-4BB1-9F7F-8546BBC72254.jpeg

61C33CF0-9987-488C-8565-18C4D541C2B2.jpeg

Is your new cowling tighter than the 201?  I sent pics of my setup a few years ago.  My air filter is behind the pilot side inlet, and the carb heat box is custom. 

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12 hours ago, rbridges said:

Is your new cowling tighter than the 201?  I sent pics of my setup a few years ago.  My air filter is behind the pilot side inlet, and the carb heat box is custom. 

Not much tighter than an original. The round inlets make it a challenge to fi the air filter low enough to not disrupt the airflow too much. I’m also trying to use as many certified parts as possible to hopefully ease my certification. Carb air box is the next challenge as the new cowling slopes up more from the bottom than the original. I still have your pictures and thank you again for sending them.

David

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29 minutes ago, Sabremech said:

Not much tighter than an original. The round inlets make it a challenge to fi the air filter low enough to not disrupt the airflow too much. I’m also trying to use as many certified parts as possible to hopefully ease my certification. Carb air box is the next challenge as the new cowling slopes up more from the bottom than the original. I still have your pictures and thank you again for sending them.

David

Anytime, and let me know if you want any more detailed pics if it will help. 

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Your post made me curious about confirming things with the Garmin 430w true airspeed and density altitude calculator, Garmin G5 and analog airspeed indicators, foreflight and winds aloft and flying a triangle course.  1963 M20D converted to retractable gear.  Zero timed engine 28 hours on it and Scimitar 2 blade prop.  My manifold pressure gauge may be reading a little lower than actual (original gauge) but according to POH charts speed is on target or a little better, fuel burn is lower, so maybe  it's fairly accurate.  At 5,500ft OAT 49F Baro 30.00" MP 23" 2400RPM IAS 160mph/139kts True Airspeed calculated to be 175mph/152kts, fuel burn 9.4 gph 100 degree rich of peak at 1312 EGT.  The average groundspeed on triangle route was 151kts, and the winds indicated things were accurate.  Christmas Day much colder, same MP and RPM and Altitude, temp was 20 degree F and Baro 30.37", TAS 178mph/155kts fuel burn was 9.8 gph EGT 1330 at 100 degree rich of peak.  My A&P and the Overhaul shop want me flying it for at least an hour continuous (unless trouble) and no less than 75% power, so per book at these settings I should be about 77%, I don't know if the more efficient new propeller boosts that at all?  If I run full rich, it's 2 mph faster and fuel burn is 11.0 gph, however my CO detector starts to show low numbers, so not combusting all the fuel.  I guess some evening I'm going to the hangar with a light inside the cowl and I contort in the cabin looking for light showing through the firewall.  I have to admit I did  enjoy the fact that my friend in a much newer C182 had a hard time keeping up and he was burning almost 50% more fuel to do the same thing.  I don't understand, after three hours he wasn't smiling like me at the fuel pump. hmmmm

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  • 2 weeks later...

When I zipped down to Rockford, IL yesterday with another fat*** in the cockpit somehow allowed me to calculate a TAS of 142-143. I normally ride solo and typically have a lot of fuel. We had full tanks and combined weight was probably 460 worth of humans. I should note that there was an active Airmet Tango regarding vicious windows from 020 to 080 blowing 50kts. We were at 085 when I calculated the TAS. Air was quite smooth.

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On 1/10/2020 at 12:47 PM, Sabremech said:

Trying to get a little more out of my C. Working on fitting the new induction system on mine so it fits under the new more aerodynamic cowling. It’s a tight fit and here’s attempt number 4 to get the air filter to fit the baffling. 
David

9069787A-A6C3-4BB1-9F7F-8546BBC72254.jpeg

61C33CF0-9987-488C-8565-18C4D541C2B2.jpeg

Seeing these pics makes me wonder again about filling in the area from the LASAR enclosure to the front of the cylinders with a piece similar to that sloping piece you have in the second picture. I would think that it could be done and improve air flow.

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5 minutes ago, aviatoreb said:

The title of this thread reminds me of an old children's poem tongue twister that goes, "How much wood would a wood chuck chuck, if a wood chuck could chuck wood?"

FTFY! It's more difficult than Peter Piper picking a peck of pickled peppers [who grows peppers already pickled? Wish I could!]

We've been having discussions here at work with some recently-arrived coworkers from facilities outside the US, revolving around textbook vs. Southern English, and what the words mean [when they can figure out what the words are]. Fun times. Cue Lewis Grizzard:  https://youtu.be/imZjCbRuZ3c 

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8 hours ago, Hank said:

FTFY! It's more difficult than Peter Piper picking a peck of pickled peppers [who grows peppers already pickled? Wish I could!]

We've been having discussions here at work with some recently-arrived coworkers from facilities outside the US, revolving around textbook vs. Southern English, and what the words mean [when they can figure out what the words are]. Fun times. Cue Lewis Grizzard:  https://youtu.be/imZjCbRuZ3c 

You outta try Pig Latin on them- it has been my experience that anyone who speaks English as a second language (no matter how well) cannot follow Pig Latin.

Itsay ethay uthtray, i-ay earsway!

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