Bob_Belville Posted July 19, 2016 Report Posted July 19, 2016 My '66 M20E left the factory at a relatively svelt 1611 pounds empty weight. With a MGW of 2575 it left a useful load of 964 pounds. CG was 45.9" 50 years have been kinder to her than to her owner. after lots of mods and improvements her empty weight has climbed by 64 ponds to 1675.5 and the useful load is down to a still respectable 899.5 pounds. But... the CG has moved back quite a bit from 45.9" to 47.4". The rear CG limit for the short bodies is 49". (Several factors, the nose got lighter with lighter starter, alternator, removal of nose wheel shimmy dampener, oil cooler moved to back of engine. added stuff with long arms: remote avionics in the battery area behind the cabin, gap seals for rudder and elevators - little weight but long arms.) The CG arm for the rear seat is 70.7" and the baggage area is 93" so it is sometimes tougher to stay forward of the rear CG than the MGW limit. (I'm no Bob Hoover but having flown quite a lot with rear seat passengers I can't say that the plane feels at all tail heavy or at risk. I would not do slow flight, stall recovery air work with CG behind the limit. I might talk to Mike Miles or Jose Monroy sometime privately for their experience. I suspect there's some margin of error @ 49" but I'm way too old to play test pilot.) So... I'm sure 3RW is hardly unique, inquiring minds would be interested in comments and possible solutions. Quote
Raptor05121 Posted July 19, 2016 Report Posted July 19, 2016 Bob, what all do you have in your plane? My no auto-pilot, bare-panel 63 M20D/C is (looking at my Excel spreadsheet now), empty weight 1571, MGW 2575, useful load 1,003lbs, and an empty CG of 44.0 Quote
RangerJim Posted July 19, 2016 Report Posted July 19, 2016 Small arithmetic errors as stuff goes in and out over the decades can add up. You might consider having the plane weighed by a knowledgeable shop equipped with a set of certified scales. It is a pain but empty fuel tanks will yield a better number. A current and accurate W&B and equipment list is a good thing no matter what you are flying. 3 Quote
carusoam Posted July 19, 2016 Report Posted July 19, 2016 PP logic for knowing your CG under actual conditions... To get a feeling for how sensitive the calulation is, add in a mythical 1lb weight on the nose. This will test how one pound on a long forward arm effects your CG calculation. Does the CG move an inch forward with 1# on that long arm? Try 2#... with my 65C, The trim wheel was full up on final approach. This is a hint of how forward the CG is in that part of the flight envelope with full flaps deployed... If your trim wheel is only going to the half position while flying solo, you may be running out of trim when you load the back... the challenge with this logic is your trim has to be working properly. If not, watch out below... know how a stall outside the CG envelope ends. Make sure you don't go there accidentally... PP ideas only. I am not an aviation expert.... Best regards, -a- Quote
BDPetersen Posted July 19, 2016 Report Posted July 19, 2016 If possible, review the math on each weight & balance update. Not uncommon to find an error. My C is at 43.9. Scales and the proper weighing procedure would, of course, yield the most accurate result. 1 Quote
Bob_Belville Posted July 20, 2016 Author Report Posted July 20, 2016 3 hours ago, BDPetersen said: If possible, review the math on each weight & balance update. Not uncommon to find an error. My C is at 43.9. Scales and the proper weighing procedure would, of course, yield the most accurate result. Yeah, I'm pretty competent with Excel and I have all the changes in a comprehensive spread sheet. I'll triple check it but it seems to be correct. Here's 2 lists - the stuff remove and the stuff added (Prior to the new panel I installed in 2012 which moved CG back a little more.) The changes documented here which presumably includes everything done from 1966 to 2001 added 77 pounds net to empty weight and moved CG from 45.9" to 47.0". The changes made in 2012 reduced the empty weight by 12 pounds but the CG moved a further aft to 47.4. Original Equipment Removed: Wt Arm Moment Rmvd Narco Mk12a w voa4 indicator (lbs) (in) (in-lbs) Rmvd factory cabin curtains -1.1 69.3 -76.2 Rmvd vacuum directional gyro -2.0 20.0 -40.0 Rmvd factory yoke clock -0.4 30.5 -12.2 Rmvd cigarette lighter -0.2 21.0 -4.2 Rmvd Brittian LSA-2 Flt Cont (Positive Control) -7.1 46.6 -330.9 Rmvd elect turn/bank indicator -1.3 21.5 -28.0 Rmvd Grimes rotating beacon -2.0 163.0 -326.0 Rmvd factory Delco-Remy generator -16.6 -19.5 323.7 Rmvd factory Delco-Remy voltage regulator -2.0 7.0 -14.0 Rmvd wing tip position light sockets -0.8 42.0 -33.6 Rmvd tail position light socket -0.4 240.5 -96.2 Rmvd factory sun visors -0.6 33.0 -19.8 Rmvd factory mechanical tach -0.8 19.0 -15.2 Rmvd mechanical tach cable -0.7 4.0 -2.8 Rmvd factory gear horn -1.0 7.0 -7.0 Rmvd factory Donaldson induction air filter -1.2 -19.5 23.4 Rmvd factory Prestolite R35 battery -28.0 105.8 -2,962.4 Rmvd factory Prestolite MZ4206 starter -17.8 -18.0 320.4 Rmvd factory nose shock absorber -2.2 0.0 0.0 END, Removed Equipment --- Net change, removed equipment: -101.7 41.1 -4184.4 Avionics & Instruments adds (1966- 2001) Pointer 3000 ELT 1.9 112.0 212.8 Pointer ELT Antenna 0.3 164.0 49.2 King KNA24 Audio w Mkr 1.7 17.5 29.8 Mkr beacon Antenna 0.4 126.0 50.4 King KY197 incl rack/connects 3.2 17.5 56.0 Comm Antenna #1 0.5 96.0 48.0 King KNS80 w GS incl rack/connects 6.0 17.5 105.0 Nav vor/gs Antenna 1.0 200.0 200.0 DME Antenna 0.4 36.0 14.4 King KX155 w GS incl rack/connects 5.3 17.5 92.8 includes KI-209 vor/gs indicator Comm Antenna #2 0.5 132.0 66.0 Narco HSI-100s (slaved) 3.6 17.5 63.0 Narco HSI flux valve & cabling 1.0 63.0 63.0 King KT76a transponder includ rack, 3.1 17.5 54.3 connectors, & KA60 antenna TransCal TCI SSD-120 encoder 0.8 14.0 11.2 King KR87 ADF 3.2 17.5 56.0 King KI227 ADF indicator 0.7 17.5 12.3 King KA44B loop/sense antenna 2.8 117.0 327.6 Garmin GPS150 w internal nicad bat, rack 2.8 17.5 49.0 Garmin GA56 GPS antenna 0.3 52.0 15.6 BFG Wx900 Stormscope display unit 1.6 17.5 28.0 BFG Wx900 Antenna unit 0.9 168.0 151.2 STEC 50 Autopilot System: Programmer/Computer 2.8 21.5 60.2 Turn Coordinator 1.8 20.0 36.0 Roll Servo 2.9 66.0 191.4 Pitch Servo 2.9 126.0 365.4 Absolute Pressure Transducer 0.2 130.0 26.0 STEC Manual Electric Trim System Servo 0105-2-T3 2.9 130.0 377.0 Hardware, switches, wiring 0.4 17.5 7.0 Northern Airborne Technology nav/gps sw 0.2 21.0 4.2 Electronics Intl R-1 digital tach 0.6 21.0 12.6 Davtron M655 5-function indicator 0.3 21.0 6.3 JPI CHT/EGT Scanner w 9 probes 0.6 19.0 11.4 4 cht, 4 egt, & 1 oil temp probe 1.2 -9.0 -10.8 Davtron M800 yoke clock 0.2 30.5 6.1 FlightCom 403 panel intercom 0.3 18.0 5.4 jacks/wiring & ptt sws front seats 0.6 18.0 10.8 jacks/wiring rear seats 0.4 70.7 28.3 Southwest Texas Aviat STCd Instrum Panel 0.0 0.0 35.8 Electronic Components Inc Gear Alert: Transducer 0.6 113.0 67.8 Computer box & switch 0.7 7.0 4.9 Cable 0.4 55.0 22.0 Aero Mods Inc Fiberglass Belly STC adds: 10.0 51.0 510.0 Aero Resources Inc 201 fiberglass cowl mod 2.0 -21.0 -42.0 Aero Resources M20J Hartzell spinner 2.0 -32.0 -64.0 Brackett Air Filter Assy 0.7 -19.5 -13.7 Concorde R35 battery 26.5 105.8 2,803.7 Jasco Skytronics 50a Alternator 6550 10.0 -19.5 -195.0 Jasco Skytronics J12M20SP Volt Reg 1.5 7.0 10.5 Lake Aero (Lasar) Modifications: Mooney 201 Wind Screen STC 0.0 0.0 0.0 Wing flap gap seals 3.5 90.0 315.0 Aileron lower gap seal mod 0.5 78.0 39.0 Rudder & elevator hinge fairings 0.3 190.0 57.0 Brake wheel cylinder rotation 0.0 0.0 -21.0 Wing root leading edge fairings 2.0 30.0 60.0 Wing wheel well liner fairings 1.0 67.0 67.0 Tail root horizontal fairings 2.5 177.0 442.5 Dorsal fin fairings 2.3 177.0 407.1 Oil cooler relocation front to rear -1.9 na -62.3 Oil cooler relocation undrainable oil reduced -0.8 na na Addit landing light & light covers 4.5 18.0 81.0 Front seat shoulder harness/belts 0.5 41.0 20.5 Tiedown ring / tail skid set -0.4 194.0 -77.6 Mooney factory rudder pedal extension kit 0.0 4.0 0.0 O&N bladder tank system, 54.8 gal usable 29.7 48.4 1,437.5 Chg in unusable fuel per O&N engineering to 1.2 lbs from 3.4 lbs orig FAA data sheet -2.2 48.4 -106.5 Precise Flight Manual Speed Brake STC 9.0 70.0 630.0 Precise Flight SVS-5 Stby Vacuum STC 2.4 -2.0 -4.8 Skytec Flywt starter 149-12LS (now Lyc part) 7.8 -18.0 -140.4 Whelen Strobe System: Pwr Supply HDA-CF-14/28 2.1 112.0 235.2 Wingtip strobe/pos lts - A650pg (l&r) 0.8 42.0 33.6 Tail strobe/pos lt A500a 0.3 240.5 72.2 Added Equipment & Modifications 178.6 53.3 9,517.7 removed equipment: -101.7 41.1 -4184.4 Net changes 1966 to 2011 76.9 69.4 5333.3 So... the whole exercise was as if we added 77 pounds in the rear seat. 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Hank Posted July 20, 2016 Report Posted July 20, 2016 Hang a Hartzell 3-blade on the nose. Flying with a buddy often outs me almost at the forward CG limits . . . Quote
MB65E Posted July 20, 2016 Report Posted July 20, 2016 Bob, I personally used your excel sheet when I did my W&B re-weigh. Thanks for providing it. That said, you have THE most complete W&B I have ever worked with. I would say your airplane might be lighter than your W&B says it is, or all of ours are heavier than we think they are. I personally have never weighed my toe bar, flash light, but have weighed mine with 6qts of oil. I'm at 916UL last checked. I'll look again before I tanker up for Oshkosh. Fun stuff to play with, but I wouldn't loose sleep over it. Aft is fast! Hope to finally meet at OSH! fly safe, -Matt 1 Quote
Raptor05121 Posted July 20, 2016 Report Posted July 20, 2016 28 minutes ago, Hank said: Hang a Hartzell 3-blade on the nose. Flying with a buddy often outs me almost at the forward CG limits . . . Just did the math with my 3-blade. two 200lbers and full fuel gives me less than an inch before im forward of CG. This is why my dream is to swap it out for a 2-blade MT composite. That would probably take 50lbs off the nose Quote
takair Posted July 20, 2016 Report Posted July 20, 2016 Bob Taking your summary number and the original seems to yield a discrepancy of about 12.4 lb, which pushes CG to 46.96. The removed equipment on your list appears to be off by 15.5. Might be worth a double check. As a point of comparison, my E comes in at about 1671.9 and 45.8.... I admit, my list is not as comprehensive as yours. Was the plane ever weighed since original? Quote
carusoam Posted July 20, 2016 Report Posted July 20, 2016 I asked siri to add up the third column... The moment of removed items... I was unable to get Siri to come up with -4184.4 Turns out seri can't do so many calculations in her head.... sorry, -a- Quote
Bob_Belville Posted July 20, 2016 Author Report Posted July 20, 2016 1 hour ago, Hank said: Hang a Hartzell 3-blade on the nose. Flying with a buddy often outs me almost at the forward CG limits . . . Hank, I think my 30 pound battery is 9' aft of yours isn't it? That's a huge difference. Quote
Bob_Belville Posted July 20, 2016 Author Report Posted July 20, 2016 6 minutes ago, carusoam said: I asked siri to add up the third column... The moment of removed items... I was unable to get Siri to come up with -4184.4 i got -3301 twice... three times... Am I doing the math incorrectly? Anthony, thanks for taking the time to double check this. In my cut/paste to MS the first line values got covered up by the column headings. The Mk12a should show -15.5 57.0 -883.5 the 883.5 is your difference. Sorry! 1 Quote
carusoam Posted July 20, 2016 Report Posted July 20, 2016 I can now see how the whole WnB thing can go awry... Best regards, -a- 1 Quote
Bob_Belville Posted July 20, 2016 Author Report Posted July 20, 2016 14 minutes ago, takair said: Bob Taking your summary number and the original seems to yield a discrepancy of about 12.4 lb, which pushes CG to 46.96. The removed equipment on your list appears to be off by 15.5. Might be worth a double check. As a point of comparison, my E comes in at about 1671.9 and 45.8.... I admit, my list is not as comprehensive as yours. Was the plane ever weighed since original? Thanks, see my reply to Caruso. I left off a line of values, totals are right, I think. Thanks for the comparison, that helps, i suppose I have more junk in the rear avionics bay than the average E. I don't have any record of the plane being reweighed and that probably is in order at this point. 3RW did have a meticulous owner (A Delta captain) from 2000 to 2005 who found so many W&B errors in the older records that he created the list above to take the W&B from 1966 to 2001 in a single document. (His spreadsheet for doing W&B calculations included headsets, charts, AFM, seat position... though I don't think he accounted for bowel movements. If he had weighed the plane I'm sure he would have used it.) Quote
Guitarmaster Posted July 21, 2016 Report Posted July 21, 2016 On July 19, 2016 at 9:25 PM, carusoam said: I asked siri to add up the third column... The moment of removed items... I was unable to get Siri to come up with -4184.4 Turns out seri can't do so many calculations in her head.... sorry, -a- Siri is an electronic bimbo. Quote
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