PARK ZONE F-4U CORSAIR Seller:harleydoberman Details:
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| 8/30/2008
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Posts: 396
Joined: 8/30/2005 From: Oklahoma City,
OK, USA Status: offline
quote:
ORIGINAL: BobH
I really like the work you're doing. The cockpit is one of my favorite parts of a plane. It's always refreshing to see some one going the extra mile to do it justice. Is your canopy goign to be air operated or servo operated? You might have said already but I missed it.
THanx Bob - It is Air Operated. Take a look at post #277 for more details.
Posts: 396
Joined: 8/30/2005 From: Oklahoma City,
OK, USA Status: offline
Well I'm ready to do the CG. I'm going to use the weight-large scale method. To do this, here is a copy of a thread I found in the RC Large Scale Forum
"Kent Porter
You wont even have to lift the plane with this method. This method is how I go about checking CG on a plane that weighs too much to put on a CG machine. This is generally the same way full scale planes are balanced. You can’t go lifting a 747 by your fingers!
First, have the plane assembled as RTF, but minus fuel. Find a place where you can put the nose of the plane up against a wall. Take a level and prop up the tail wheel until the fuselage is sitting level. You will probably have to take the hatch off in most cases to find a suitable area to set the level on. Once the plane is sitting level, place masking tape under the area where the main wheels are touching the surface and draw a line where the wheels contact the tape. Make an index mark where the center of the tailwheel falls in the same manner. This mark will be on whatever you propped the tail up with. (I use magazines). It’s also a good time to measure from the wall, to the point where the recommended CG is. Save that number for later. What you are looking for at this point is the distance to each wheel from the tip of the spinner. (which should be touching the wall at this point) I use a long straightedge to get the distances As an example, let’s say you come up with theses numbers: LH main – 22” RH main – 22” Tailwheel – 70” Now, place a scale under each wheel individually. You will have to re-adjust the height of the other wheels each time to keep the plane sitting level. Add more magazines as necessary. (If you have three scales you can get the weights at the same time but make sure the plane is level) Don’t forget to re-install the hatch before you weigh each wheel. You will wind up with three weights, one for each wheel. Let’s say you come up with these numbers LH main – 9 lbs RH main – 9 lbs Tailwheel – 5 lbs Now its just a simple math problem to find where the CG sits right now on the plane. Weight x ARM (distance) = Moment 22x9=198 in-lbs 22x9=198 in-lbs 70x5=350 in-lbs Now add the total of all the moments and the total of all the weights. Weights 9+9+5 = 23lbs moments 198+198+350 = 746 Then divide the total moments by the total weights. 746 divided by 23 = 32.43 That number 32.43 is "in inches" how far back from the tip of the spinner to where the plane balances right now. Compare that to the distance that you measured earlier to the recommended CG location. If you are off one way or another adjust items then recalculate the weights. The distances (or ARM's) arent going to change so you already have those numbers.
It may sound confusing and a lot of work but it really only takes about ten minutes to do it.
Posts: 396
Joined: 8/30/2005 From: Oklahoma City,
OK, USA Status: offline
Ok I started this CG thing. Believe it or not, even with that anchor of an engine, she's still tail heavy. THis raises a slight issue, where to put the battery. I could put it way up front in the engine compartmennt, but I am concerned about noise.
ANy input from anyone? I could use a little advise here. I am using a Futaba transmitter 9C with the Spectrum Module (2.4 GHz.) THe receiver is a Spectrum AR9000, again 2.4 GHz. Should I not put the battery near the engine? Please chime in with thoughts.
Posts: 396
Joined: 8/30/2005 From: Oklahoma City,
OK, USA Status: offline
I've created a CG Locator Spreadsheet in both Excel and QuatroPro using the above method. All you have to do is enter the weights and distances and it will then calculate the CG for you. If anyone would like it, just send me your email and I will be happy to send it to you.
Posts: 200
Joined: 12/15/2002 From: MANHATTAN BEACH,
CA, USA Status: online
Hi Andrew, Every RF device is susceptible to radio frequency interference. The ignition system generates a lot and the receiver will be exposed to it. Putting the two in close proximity is never a good idea regardless of the frequency. How much ballast is required? We have all been through the same agony. An ounce of lead is worth a pint of blood. Sacrifice the blood for the safety of the plane. Use lead. Dan
Posts: 396
Joined: 8/30/2005 From: Oklahoma City,
OK, USA Status: offline
Dan - Right now she weight about 33 lbs minus the Receiver battery. Roy's specs call for 28 - 34 lbs. So far I'm in spec, but as you know, I am nervous about adding more weight. I don't know how much more is needed - yet. I think I may make a my own cg machine and then compare that with the method above. THanks for you input. It all helps me figure this one out.
Posts: 134
Joined: 12/19/2001 From: Leesburg, GA, USA Status: offline
Hi Andrew,
Don't worry about adding weight to get the C/G correct, most of the guys I know that are flying FW 190 has added a bunch of lead (2 to 5 lbs.). I personally added 4 pounds to my new American Eagle FW 190 , the first (RIP) had around 3 1/2 pounds and was a little tail heavy(weight was 31 lbs.), before I totaled it at 2006 "War Birds Over Atlanta". AE FW190 is about the same size as Vailly FW190, the new one came out at 38 pounds and after the maiden flight I removed about 4 pounds and adjusted the C/G weight to get back to my 5.5"' C/G, I remove the bomb drop pylon w/servo,bomb,compete copit, pilot, choke servo, and any thing else I could get by she just under 34 pounds now. Good Luck Charlie
< Message edited by Kickin Chicken -- 7/2/2008 2:44:55 AM >
Posts: 396
Joined: 8/30/2005 From: Oklahoma City,
OK, USA Status: offline
Great Pics Charlie and thanks for the info. I've had to add a little over 4 lbs and waiting for some zap a dap a goo to dry to test the CG again. Total weight is about 38.5 lbs. Not what I expected. So its good to here that I am not alone on this issue. Keep em flying and agian, great pics.
Posts: 396
Joined: 8/30/2005 From: Oklahoma City,
OK, USA Status: offline
I don't know about you all, But I'm an absolute klutz when it comes to moving my planes. So, I started to make some bags. A seamstress I am not, but they should work just fine. I'll be making one for the wing and fuse, also.
Posts: 34
Joined: 7/18/2006 From: NAPLES, FL, USA Status: offline
everything looks awesome , are you planning on doing any weathering to the aircraft before its maiden? i installed the batteries on my yak on top of the engine box due to short nose moment and what ive found is a shortened battery life im atributing to vibration and possibly heat . what ive heard as rule of thumb be that all radio electronics be at least 12" away from ignition source if at all possible . i have not had interference due to this but why risk it if you dont have to. lead is safer. well andrew looks like your next mission might be taxi trials .....real nice cockpit by the way
Posts: 396
Joined: 8/30/2005 From: Oklahoma City,
OK, USA Status: offline
Thanks for the info Art. I agree wtih keeping the electronics away from the engine, but as this plane has such a short moment, I feel as though I have no choice (or no room). NOt going to do any weathering. I like a clean look on my birds. I still need to finish up on the CG then its engine break-in and taxi trials.
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RE: Vailly FW 190 Build - 
