Brodhead Pietenpol Association

Original Posted By: "walter evans"
I am ready to start the weight balance process. I know that this has been discussedmany times. I have been in the archives searching for the info but no luckyet. Does anyone have a full explaination of the complete process for a shortfuse with an A-65?Dick________________________________________________________________________________

Original Posted By: "Richard Navratril"
If you are looking for a program to do it with, this one was the best (supplied by someone on this group) Here is the program that I used formaxed out gross. You can plug any numbers in that you want. ( hopefully youhave windows EXCEL)If you are looking for a basic explanation of how to do W&B, let us know.Me or others can explain. When you hear it , it seems like Greek, but whenyou really do it, it's really easy.Let us know.walt----- Original Message -----

Original Posted By: "Richard Navratril"
Richard, Go to this page on my web site. The exel program is there and thereis another formula you can use if you don't have exel.http://members.core.com/~skycarl/weight ... lCarl----- Original Message -----

Original Posted By: Kip & Beth Gardner

Original Posted By: "walter evans"
Walt Thanks for the response. I have a handle on the basics, I should havebeen more specific. I need to know what the FAA is going to want to see fora w/b worksheet in my operation manual. Also I was interested in the worksheets to do it.Did you send an attachment or a site, if so it didn't come through. I haveexel at work, I can forward it on.Dick----- Original Message -----

Original Posted By: Rcaprd(at)aol.com
Subject: Re: Pietenpol-List: weight balanceIn a message dated 12/2/02 6:14:28 PM Central Standard Time, horzpool(at)goldengate.net writes:>Dick, This is the configuration that I am going to end up with, too...short fuselage, Continental A65 engine. I would be very interested in hearing any info about how others have their plane set up. I did the weight & balance on paper, and have concluded that I have to extend the engine mount 8" longer than the plans drawings, to maintain a safe center of gravity range with my 210 lb body in the pilot seat. Although I'm using heavier wall tubing than the plans call for, this extension of the motor mount seems excessive to me, and I would like to hear some input about it. I used the firewall as the datum, then subtracted the distance the leading edge is from the firewall, to attain the location of the C.G. on the wing chord. On my plane the leading edge is 11" behind the firewall. The plans show 7 1/2" behind the firewall, which puts me 3 1/2" aft of vertical cabane struts. B.H.P. said the C.G. should not be behind 1/3 of the chord. 60" chord divided by 3 = 20" behind the leading edge, for the aft C.G. limit. This seems excessive to me, as I have never heard of any other plane with an aft C.G. limit this far back. An aft C.G. is an efficient place to operate, but gives touchy pitch control. Aft C.G. frightens me. Several times, I've seen the results of an aft C.G. in model airplanes. The wing stalls, it enters a spin and ya just can't get it out, and it will spin all the way to the ground. In World War I, some pilots would wear parachutes, and if they entered a spin, they would bail, only to see the plane recover by itself, now that the aft C.G. no longer existed. The weight is measured in pounds. The arm is measured in inches. Back in the 'Old Days' they used the firewall as the datum. The problem with this, is anything ahead of the firewall is a negative arm. These days, they use the tip of the spinner, or even several inches ahead of the spinner, as the datum. This keeps all arms a positive number. When you remove weight, you also use a negative number. To get the center of gravity, multiply the weight times the arm, then you add the weight, add the moment, then divide total moment by the total weight. Pretty simple. (there was 1gal fuel onbd)ITEM WEIGHT ARM MOMENTL. Main 332 17 5644R. Main 342 17 5814Tail 14 161 2254total 688 1371213712 / 688 = 19.93 -11" = 8.93" aft of leading edge for my Empty Weight Center of Gravity (E.W.C.G.), with the Model A engine, and 13lb lead ballast under the nose cone.ITEM WEIGHT ARM MOMENTL. Main 332 17 5644R. Main 342 17 5814Tail 14 161 2254Pilot 210 64 13440Fuel (8gal) 48 33 1584total 946 2873628736 / 946 = 30.37 - 11 = 19.37" aft of leading edge with Model A engine, full fuel & 210lb pilot.Now I remove the Model A engine & ballast, and add a Continental A65 engine:ITEM WEIGHT ARM MOMENTL. Main 332 17 5644R. Main 342 17 5814Tail 14 161 2254Ballast -13 -23 299Model A engine -225 -12 2700A65 w/stock mount +175 -17 -2975total 625 1373613736 / 625 = 21.97 - 11 = 10.97" aft of leading edge E.W.C.G. with Cont. A65.Now I take these numbers, and add fuel & pilot:total 625 13736Pilot 210 64 13440Fuel 48 33 1584total 883 2876028760 / 883 = 32.57 - 11 = 21.57" aft of leading edge, with Cont. A65, pilot & fuel. UNACCEPTABLE I kept adding to the arm of the A65 engine, till I got to 8" extra arm, to attain a safe C.G. of 19.98" aft of leading edge. Still not much of a margin of safety. My question is this: Is an 8" addition to the plans length of the A65 engine mount, too much? What to do? I'm ready to weld it up.Chuck GantzerNX770CG-what to do in the Land of Oz________________________________________________________________________________

Original Posted By: "Richard Navratril"
Dick,I sent it as an attachment but guess it got booted.Oh well. What I did was to to all my figuring on the excell program (four different sceneros, pilot and pass w/full fuel all the way to pilotonly with low fuel in nose tank)Then put the data on a sheet based on what Corky posted. The DAR said itwas fine and sent it along.What I didn't like about the excell was, although it was great to figure onand instantanious in the results, It seemed kind of overwhelming to read atfirst glance. Afterall it is supposed to be in the plane so a pilot can seeif he's in the window at a glance.The final document I put on WORD and I'll send it to you directly.walt----- Original Message -----

Original Posted By:
ChuckI think I see your problem. It appears that when you did your second set ofcalculations that you subtracted the weight of the Model A and added theA-65 but your figures for the three weight points did not change. I don'tthink that you can assume that.----- Original Message -----

Original Posted By: flyboy_120(at)webtv.net (Ed G.)
Subject: Re: Pietenpol-List: weight balanceIn a message dated 12/3/02 9:50:38 PM Central Standard Time, horzpool(at)goldengate.net writes:>In doing weight and ballance, the initial total weight is attained by adding the numbers on the scale (less tare weight). The reference is the center of gravity. The datam was the firewall, where the measurements were taken from. When you subtract or add weight (on paper), the total weight changes, as does the C.G. The total weight did not stay the same, as the numbers indicate. Chuck G.________________________________________________________________________________