FloridaMan Posted February 17, 2015 Report Posted February 17, 2015 Are we doing this again? 1967 M20F, LoPresti Cowl, GAMI injectors, PowerFlow exhaust, gap seals on Ailerons and flaps and it has the vertical stabilizer mod. 20deg mag timing and 158ktas at 6500ft. 165mph IAS. I did that back in the fall when it was warm here in Florida and I swear it's actually a little faster now that it's cold outside. The brake caliper mod hasn't been done yet and it has the single gear doors still. Getting an EDM900 installed next month and I may be able to run it more aggressively; as for now, I run it conservatively ROP. Quote
carl Posted February 23, 2015 Report Posted February 23, 2015 This would be cool if you compiled all this data into an excel sheet for comparison. What does WOT stand for? I'm guessing wide open throttle? carl 1 Quote
bonal Posted February 23, 2015 Report Posted February 23, 2015 WOT you are correct sir give that man a cigar. Got 155 knots true today at 6500 at 2500rpm and 23mp. Quote
Hank Posted February 23, 2015 Report Posted February 23, 2015 Careful there, bonal! The Key Number for our engines (MP + RPM) is 47; you're flying at 48, which puts you in the edge of the danger zone. My MAPA PPP books are in storage (oh, the joys of moving!), but surely someone here has access to them and can post the significance of the number. At 6500 msl, I generally use 2400 RPM. Quote
bonal Posted February 23, 2015 Report Posted February 23, 2015 Careful there, bonal! The Key Number for our engines (MP + RPM) is 47; you're flying at 48, which puts you in the edge of the danger zone. My MAPA PPP books are in storage (oh, the joys of moving!), but surely someone here has access to them and can post the significance of the number. At 6500 msl, I generally use 2400 RPM. I would welcome more info on the subject I certainly did not feel that I was stressing things. Today's flight where I got those numbers I was able to get 25 squared and pulled 2 inches out with throttle and things seemed very relaxed with a pretty aggressive lean and an altimeter at 29.89 and OAT at 45 deg Fahrenheit Quote
carusoam Posted February 23, 2015 Report Posted February 23, 2015 Bonal, MAPA training 101... If you get the chance, it is worth it! Best regards, -a- Quote
Cruiser Posted February 23, 2015 Report Posted February 23, 2015 The Key Number "Frequently we may want to set MP and rpm to develop a certain percent of rated horsepower. For normally aspirated engines, the "key number" approach provides an easy means without having to refer to power tables. Simply stated, for "green arc" rpm ranges, add the rpm in hundreds to the MP to arrive at our key number. For example, "23 square" gives a key number of "46". For moderate altitudes (2,000 - 10,000 MSL) the M20J key numbers are "50" for 75% of rated power, "47" for 65%, and "44" for 55% power. For the M20F, the key numbers are "48" for 74% of rated power, "45" for 64%, and "42" for 55%. The "key number" is a handy way to determine equivalent power settings. Given a set of MP and rpm values, calculate the "key number"; then develop alternative combinations of MP and rpm having the "key number" and hence the same power." MAPA Safety Foundation MPPP page 4-4 Quote
Hank Posted February 25, 2015 Report Posted February 25, 2015 That's it, Dave, the numbers are easy to remember. What is escaping me right now is the underpinning to this. Sure, the house looks nice from the road, but 2-story frame, brick and post-and-beam are all very different, and the roof on each will support different loads of snow, Christmas decorations and me walking around. I have some favorite power settings from the Book, but always have good old 46 - 47 to fall back on during IFR level offs on departures and pre-arrival descents. Unlike our LOP brethren, we can't just leave it at WOT from departure through pattern entry. Looks like bonal is doing alright, he's just running a little harder than I do, but safely so if he's leaned out well. I may adjust myself to 46 down low, 47 at mid altitudes, and whatever I can get at 8000 and up. Wonder what (WOT less a smidgen) and 2600 will do for me? Quote
bonal Posted February 25, 2015 Report Posted February 25, 2015 Thanks Hank, I try to fly Snoopy fast but smart. I almost always pull an inch or two out when I see close to 25 and keep it to 2500 I remember reading that a lower RPM gives a better delivery of power or something like that. I guess this is why I'm getting almost 150 knots true. Of course when I'm above 7500 feet im lucky to get much better than 23 inches at WOT. I don't know seems like the stories you all share about flying in some of the crap freezing weather and such is a lot harder on a plane than what I'm doing. Please be careful everyone it's real nasty out there. And a broken hip is worse that an overhaul any day. Quote
Jsavage3 Posted February 25, 2015 Author Report Posted February 25, 2015 I had a good flight a couple days ago to Charleston, SC -- took my family down there to tour an aircraft carrier, a destroyer & a submarine at Patriot's Point...that was a BIG hit with my two young sons! Based on what they keep asking to watch on tv, my wife & I figured out that they've recently developed an interest in naval vessels... At 9,000', I had a solid 161 KTAS with WOT 22"MP (ram-air open), 2500 RPM, 25 ROP and 9.4 GPH. Had a nice tailwind to boot, so it was a pleasantly quick trip down...had a bit of a headwind coming back though, so that added about 30 minutes to the return trip. Quote
Hank Posted February 25, 2015 Report Posted February 25, 2015 I don't have much Mooney experience yet Hank, and watching our temps I absolutely agree - we can't go WOT takeoff to pattern like our LOP brethren - but I sure do wish I could get our C to go a lot faster! I have been cruising at 7000'-9000' (unless headwinds dictate otherwise) WOT less a smidgen to see the needle budge, and I like 2400 ... It's quieter to me ... (So, by the. numbers that puts us running at about 65% (21-22 +24=45/46) ... after all the speed mods and intake exhaust changes ... I am accepting that what I get ... is what I get ... Not sure there's much more speed to be had? Unless I go with an Aero Resources cowl mod and 201 windshield? (Not cost effective for me at this point) That's what I do, but that high I run 2500; I save 2400 for 4500-6000-ish feet, trips less than an hour. Short hops are generally 3000 msl, 23/2300. Works for me. Since fixing my carb heat last month, speed at 3000 is now up to 150 mph. Haven't gone anywhere far since, but soon will. Quote
Lood Posted February 25, 2015 Report Posted February 25, 2015 1967 stock M20F: 2450 rpm, WOT, 75 deg ROP, 9.7GPH,142KTAS Quote
KevinR Posted March 17, 2015 Report Posted March 17, 2015 1986 M20K 252 Rocket I usually fly between 10,000' and FL180. Fanatically keep the temps below 380. I plan on 20 gallons for the first hour and 15 for each additional hour. With 100 gallons usable and a conservative fuel reserve, she is an honest 5 hour, 1,000 NM airplane. Short trips < 250 NM I'm averaging 178 kts chocks to chocks and 17.7 GPH average for the entire flight. Rockets are thirsty down low and while climbing. I climb at the best rate where I can keep the #3 cylinder under 380. On a standard day that gives me 1,500 FPM at 120-130 kts. 1,000 FPM @ 140 kts when it's hot outside. Weight doesn't really seem to matter very much. Long trips are where she really shines; a recent trip from central Florida to Chicago was 946 miles direct, 4:24 up and 4:13 home. Total burn for the round trip was 141.8 gallons, 16.49 GPH and 220 kts. average. Yes, I had a little tailwind. Real world: 12,000' 182 kts @ 14.2 GPH / 194 kts @ 16.4 GPH / 198 kts @ 18.3 GPH 18,000' 196 kts @ 15.3 GPH / 200 kts @ 15.7 GPH The 252 is certified to fly at FL280 but i don't think the reward is worth the risk. Maybe with a second pilot on board. Yes, I always fly with a pulse oximeter and a few cans of backup O2, I had one ride in an altitude chamber 17 years ago that made an impact on me. I doubt my lungs have become more efficient since then. I owned a J model ten years ago; she was a fantastic airplane. The Rocket is the right choice for my mission now: usually solo, often long legs, solid IFR traveling machine. I truly can't imagine a better personal traveling machine... unless it was pressurized and pushed along by two engines built by Pratt & Whitney :-) 3 Quote
mooneyflyfast Posted March 17, 2015 Report Posted March 17, 2015 To make true airspeed numbers meaningful they need to come from a four way or 3 way gps average. There is too much variation in airspeed indicators for us to have a lot of confidence in calculated TAS numbers based on IAS. Also, reading the IAS number is a little subjective for me. Even in smooth air the needle will move up or down 3 or 4 knots within a one or two minute period. There is a deduction to be made at least on my 81 J model for calibrated airspeed (which is supposed to be used in the TAS calculation) from IAS. Quote
Cyril Gibb Posted March 17, 2015 Report Posted March 17, 2015 The Key Number "Frequently we may want to set MP and rpm to develop a certain percent of rated horsepower. For normally aspirated engines, the "key number" approach provides an easy means without having to refer to power tables. Simply stated, for "green arc" rpm ranges, add the rpm in hundreds to the MP to arrive at our key number. For example, "23 square" gives a key number of "46". For moderate altitudes (2,000 - 10,000 MSL) the M20J key numbers are "50" for 75% of rated power, "47" for 65%, and "44" for 55% power. For the M20F, the key numbers are "48" for 74% of rated power, "45" for 64%, and "42" for 55%. The "key number" is a handy way to determine equivalent power settings. Given a set of MP and rpm values, calculate the "key number"; then develop alternative combinations of MP and rpm having the "key number" and hence the same power." MAPA Safety Foundation MPPP page 4-4 Curious. Why are the key numbers for an E/F and a J different? All IO360s ... just with different accessories. Same displacement, same compression ratio, same bore/stroke. Is it the 20 vs 25 degree timing? That would also depend on the year would it not? 1 Quote
PaulB Posted March 17, 2015 Report Posted March 17, 2015 To make true airspeed numbers meaningful they need to come from a four way or 3 way gps average. There is too much variation in airspeed indicators for us to have a lot of confidence in calculated TAS numbers based on IAS. Also, reading the IAS number is a little subjective for me. Even in smooth air the needle will move up or down 3 or 4 knots within a one or two minute period. There is a deduction to be made at least on my 81 J model for calibrated airspeed (which is supposed to be used in the TAS calculation) from IAS. I would love to see a comparison between the 4 way gps average and a calculated TAS based on IAS. I bet there's only a 1-2 knot difference. Quote
Shadrach Posted March 17, 2015 Report Posted March 17, 2015 67 F Bone stock, original paint. 152kts @100ROP, WOTRAO, 2500RPM @ 7500FT ~10.5GPH 146kts @ 10LOP, WOTRAO, 2500RPM @ 7500FT ~ 9.5GPH We don't have FF in the cockpit so my burn is conservatively estimated. Useful 1059lbs FFpayload 675 Range - way more than I need (well over 1000 when leaned for best economy at altitude). I have done quite a few 5 hour legs when alone. But I keep legs under 4hrs with pax. These are average numbers. I've done better...and worse. Some of my highest indicated numbers have occurred at 2500MSL WOTRAO, 2500RPM and 40-50LOP. I often do this when I am alone and westbound to stay out of the wind. Quote
HRM Posted March 18, 2015 Report Posted March 18, 2015 The Mistress has done Mach .32, but we may have been in a dive. Quote
HRM Posted March 18, 2015 Report Posted March 18, 2015 Curious. Why are the key numbers for an E/F and a J different? All IO360s ... just with different accessories. Same displacement, same compression ratio, same bore/stroke. Is it the 20 vs 25 degree timing? That would also depend on the year would it not? I have asked this myself. The E is shorter, lighter and has a retractable step. Put the 201 speed mods on her and you have a shorter, lighter 201. Needless to say, my E has seen 201 and did not come apart. Quote
Hank Posted March 18, 2015 Report Posted March 18, 2015 Way to go! I've seen 205 mph groundspeed, while safely indicating almost 170 mph in an easy 500 fpm descent. Does that count? Quote
Marauder Posted March 18, 2015 Report Posted March 18, 2015 Way to go! I've seen 205 mph groundspeed, while safely indicating almost 170 mph in an easy 500 fpm descent. Does that count? Perhaps... But this does. Flew yesterday with a little tailwind help was up 211 mph Sent from my iPad using Tapatalk Quote
Hank Posted March 18, 2015 Report Posted March 18, 2015 Perhaps... But this does. Flew yesterday with a little tailwind help was up 211 mph Sent from my iPad using Tapatalk But . . . But . . . But . . . Shouldn't your F be at least 10 knots faster than my C, if not 15 faster? 180 hp, carb, chin, etc., all get in my way, to say nothing of the well-balanced 3- blade prop. Quote
aaronk25 Posted March 18, 2015 Report Posted March 18, 2015 What is all this 46 and 47 talk. Sounds like some over educated bean counter came up with a dumb idea and got others to believe in this.... So what about me on my J where I just overhauled the engine and re-used my cylinders because they still met new limits......you know how I cruise? Balls to the wall. Always 2700rpm full throttle! Even at 4000 ft I'll run 2700rpm full throttle peak egt or slightly ROP say 25-30ROP, whatever gives the fastest cruise 166kts on as little fuel as possible. about 12-12.3gph. Great baffling and power flow keeps CHTs under 380. All this "abuse" and my engine uses a QT of oil every 12 hours or so. This red box or 46,47 stuff is ridiculous in my opinion I say just don't get it hot. Keep CHTs under 380 and your in good shape. Beyond that the only thing that matters is HOW FAST DO YOU WANT TO GO AND HOW MUCH FUEL TO YOU WANT TO BURN! Internal cylinder pressures. So what. Autos and slot of other engines run slightly ROP. They don't come apart. There isnt a lot of documentation on the subject but it seems the only head to barrel separations we hear about is high CHT running cylinders. The Pistons and rings don't really care how fast they move or how much pressure is on them, it's heat that fatigues parts. Quote
mpg Posted March 18, 2015 Report Posted March 18, 2015 64' M20 D/C WOT, 2500 RPM, 50 ROP, 9500 MSL 137-138 KTS TAS 8.5 GPH, @18MPG. 3 blade prop. Checked it many times both with wiz wheel and GPS On a good day maybe 140 KTS on a bad day 135 KTS. No mods. I've been pondering this C,,, but, Why would anyone brag about 134 MPH? = 117 KNOTS? Instead of what should probably be 134 Knots = 155 MPH? 1963 MOONEY M20C • $27,000 • AVAILABLE FOR SALE • 63 Mooney M20C 4946 TTAF, Engine 1312 SMOH (1984). Last compressions 78+. Prop 483 SMOH with new style hub. Avionics King KMA 24 Audio with 3 light marker, Dual KX 155s, KI209 & KI 208 indicators, Apollo GX55 GPS, KT 76A Transponder with mode C, TXP check 1/2014, PS Engineering CD player and Intercom system, JPI Fuel computer. Flap gap seals, Cowl closure and brake STC. Annual 09/2014, Compete Logs. Paint a 5 Interior an 8. 135 MPH on 8-9 GPH. A fuel sipper not guzzler. Ph: 606-776-6165 for Adam. Plane is located at KSYM. • Contact Danny Mabry, Owner - located Morehead, KY USA • Telephone: 606-776-4013 . 606-784-7575 . • Fax: 606-783-1337 • Posted February 28, 2015 • Show all Ads posted by this Advertiser • Recommend This Ad to a Friend • Email Advertiser • Save to Watchlist • Report This Ad • View Larger Pictures Anybody think I should buy it anyway? Quote
ArtVandelay Posted March 18, 2015 Report Posted March 18, 2015 I would ignore all performance claims, just too many variables: instrument error, miscalculated TAS if at all, plane was a little bit of a descent, etc What's important is the condition of the plane: corrosion? Engine condition? Etc... POH has the performance specs, I found they are very close, even with some speed mods Quote
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