Van Thornock Posted December 7, 2020 Report Posted December 7, 2020 The weight and balance envelope on my 1982 Mooney M20K with a 305 Rocket conversion is so nose heavy that the weight and balance envelope will hardly allow for pilot, copilot and fuel without exceeding weight limitations or forward CG limitations. Let alone adding any passengers and luggage. Can tail ballast be added to bring the CG more Aft. Who is authorized to do it and who has the knowledge to do it? 1 Quote
N201MKTurbo Posted December 7, 2020 Report Posted December 7, 2020 A friend of mine did a field approved modification to add as much as 120Lbs. to the tail. The modification was DER approved and the FAA said they would approve the modification any time. I can get you in touch with him if you would like. After the mod, you can change the amount of weight in about 1/2 hour. Quote
Van Thornock Posted December 7, 2020 Author Report Posted December 7, 2020 Thank you for your reply. I would would like to contact your friend or have the person write me at vanthornock@gmail.com Quote
kortopates Posted December 8, 2020 Report Posted December 8, 2020 (edited) That's probably a little drastic of a starting solution. I'd suggest first starting with the guidance in the M20K service manual to install the proper "charlie" weight in the tail to bring the airplanes CG into the proper location. Of course it will depend on what if any Charlie weight(s) are already in the tail but any A&P can follow the guidance from the service manual with a log book entry. The weights can be ordered via any MSC. Edited December 8, 2020 by kortopates 3 Quote
Van Thornock Posted December 8, 2020 Author Report Posted December 8, 2020 Thank you for the information. That is very helpful. Quote
carusoam Posted December 8, 2020 Report Posted December 8, 2020 There are quite a few discussion regarding Charlie weights around here... If you want to become more comfortable with the topic... Essentially, Our Mooneys have so many configuration options... it takes some balancing options to best keep them in the envelope... Lead bricks bolted in place are pretty low cost ballast weights... available directly from Mooney. If UL is really important to your flying... There are also some really expensive ways to lighten the nose... Find the MT prop that goes on your ship... PP thoughts only, not a mechanic... Best regards, -a- Quote
ArtVandelay Posted December 8, 2020 Report Posted December 8, 2020 A friend of mine did a field approved modification to add as much as 120Lbs. to the tail. The modification was DER approved and the FAA said they would approve the modification any time. I can get you in touch with him if you would like. After the mod, you can change the amount of weight in about 1/2 hour.Would it not be better to get a DER to move the battery(s) further aft? Quote
Van Thornock Posted December 8, 2020 Author Report Posted December 8, 2020 I like the batteries aft suggestion. I would really rather not add mor dead weight to the aircraft. Quote
carusoam Posted December 8, 2020 Report Posted December 8, 2020 Sounds expensive... Have you seen how far back the batteries are already? Do you have the sliding board used to exchange batteries? Have you swapped out a battery in its current location already? Does the XC version of your current battery exist..? this gives a couple of extra useable pounds in the back... it’s more lead, but stores more electrons... PP thoughts only, not a mechanic... Best regards, -a- Quote
RLCarter Posted December 8, 2020 Report Posted December 8, 2020 Not a popular suggestion around here because you might loose UL, I would have it weighed according to the manual to see if the empty weight and CG are even correct 3 Quote
PT20J Posted December 8, 2020 Report Posted December 8, 2020 Anyone know why they call them “Charlie” weights? Quote
N201MKTurbo Posted December 8, 2020 Report Posted December 8, 2020 15 minutes ago, PT20J said: Anyone know why they call them “Charlie” weights? My best guess is counterbalance. Quote
Hank Posted December 9, 2020 Report Posted December 9, 2020 4 hours ago, PT20J said: Anyone know why they call them “Charlie” weights? Charlie Taylor? Or Mooney-specific, Charles Dugosh? Who first put them in a long body? Quote
carusoam Posted December 9, 2020 Report Posted December 9, 2020 There seems to be some more complex WnB details that go with larger planes... A) All the people and stuff... B ) All the fuel C) Ballast... This allows them to discuss things like zero fuel weight... important detail to not bend the wings in flight... Of it could be in honor of one Charles Taylor... Charles was probably responsible for the first WnB calculations on a powered, heavier than air, airplane... PP guesses only, may not be even close... Best regards, -a- Quote
Johnny_SA Posted December 9, 2020 Report Posted December 9, 2020 Hi Van Just did this exercise with our 231 and added the Charlie weights with great success. The added weight is not as big a penalty as the forward CG. It made a big difference on take off and landing, still monitoring speed. We use to have a CG of 40.6 (after installing a 3 blade prop) With this I had to add a lot of weight in the baggage and reduce fuel to get in the limits of the CG box. Pilot only 231 lb, 76 USG fuel, then I have to add at least 90lb in baggage. Pilot 231 lb, co-Pilot 231 lb, can only take 48 USG fuel because I need 140 lb in Baggage to get to the limit the box. Now with all 3 Charlie weights installed, CG is now 42.85, this gives me: Pilot only 231 lb, 76 USG fuel, Don't need to add any weight in luggage, just the normal 20 lb of stuff in the back. Pilot 231 lb, co-Pilot 231 lb, can only take 54 USG fuel because I need 70 lb in Baggage to get to the limit the box. A passenger in the back makes the W&B calculation a lot easier in my case. I have two options left to get the CG more aft: 1 - re-install the oxygen bottle 2 - Work on that Pilot Weight (Will be jumping on that water-rower more often) 3 Quote
Blue on Top Posted October 25, 2021 Report Posted October 25, 2021 I don't want to be a wet rag on this conversation ... and reignite the topic a year later, but this whole topic is scary to me. Center of Gravity position is not just CG of the airplane. Moments of inertia play a huge part, too, not only in longitudinal and directional stability but departure recovery, too. In other words, if I have 400 lbs. of useful load remaining to get to maximum gross weight, how it is loaded is critical. If I put all 400 lbs. at the current CG, the CG remains the same and the characteristics will change only due to the weight increase. But, if I put 300 lbs. in the nose (5' forward) and 100 lbs. in the tail (15' aft), the CG is still the same, but the inertial characteristics of the airplane will be much, much different! An autopilot will need to fly the airplane a little differently. Recovery from an upset will be a lot different. Look at an ice skater, inertia (spinning) characteristics a much different with ones arms out fully and tucked into their body. I know a couple airplanes that can't certify with small tip tanks. And, technically, doing acrobatics in an Extra with any fuel in the wings is prohibited. Fly safe! -Ron Quote
PT20J Posted October 25, 2021 Report Posted October 25, 2021 Vividly remember the first time I flew a C-310 with full mains (which are the tip tanks). 1 Quote
OR75 Posted October 26, 2021 Report Posted October 26, 2021 didn't the rocket conversion STC come with a moving of the battery (or 2 batteries) further aft ? Quote
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