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Having trouble Balancing: Top Flite P-51D Mustang 60ARF:

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Having trouble Balancing: Top Flite P-51D Mustang 60ARF:

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Old 01-05-2018, 07:24 AM
  #1  
gregoryshock
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Default Having trouble Balancing: Top Flite P-51D Mustang 60ARF:

The ARF Kit: https://www.towerhobbies.com/cgi-bin/wti0001p?&I=LXTDF5

The ARF Manual: Click image for larger version

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The Review: Top Flite P-51D Mustang ? 60 ARF

I have several questions.

The Manual isn't clear enough for me. To find the C.G. The manual says to measure back 5-5/8 Inches from where the wing meets the fuselage. Is the wing fillet apart of the fuselage or is it considered part of the wing? Where did you messure from? (I think I figured this out, but I still want feedback to make sure I did)

I have my Battery and Receiver installed where the retract air tank would be installed. Which puts those two just in front of the servo tray. I'm trying to balance the model upside down with the retracts up. As in up in the wing. The plane appears to be very nose heavy. How much weight did you need to add to tail? My engine is an OS .75 and the splinner is the stock one that came with the ARF kit.

According the review he had to move his battery and then add an ounce of weight. I'm already over an ounce of weight.

The attachments is a picture of where I currently have the battery pack and receiver.
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Old 01-05-2018, 07:44 AM
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The wing leading edge, not the fillet
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Old 01-05-2018, 11:24 AM
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I looked up the engine I want to fly the plane with: https://www.towerhobbies.com/cgi-bin/wti0001p?&I=LXRPD2
Mine weight: 26.46 Oz

I looked up the engine that guy did in the review: weight: 23 Oz

That could explain my Balance issues. I still want to know how much weight some of you had to add to your tail.
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Old 01-05-2018, 01:51 PM
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My buddy and I just finished up his with a dle 20 ra upfront and we had to add 3.5-4.0 ounces in the tail. I can't remember the exact weight, but it was in that range. He thought around 6.0 ounces. We balanced for the cg to be in the middle of the range. We used tire weights glued to the former in front of the tailwheel.
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Old 01-05-2018, 02:53 PM
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Originally Posted by spitfire66 View Post
My buddy and I just finished up his with a dle 20 ra upfront and we had to add 3.5-4.0 ounces in the tail. I can't remember the exact weight, but it was in that range. He thought around 6.0 ounces. We balanced for the cg to be in the middle of the range. We used tire weights glued to the former in front of the tailwheel.
How much does the dle 20 weigh?

Pictures attached is how my Dad and I are adding weight.
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Old 01-05-2018, 04:09 PM
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Gregg, I wound up cutting the area in back of the the tail wheel and made a hatch. I installed the battery under the hatch with an extension cord up the the switch. Have been flying this way for years. Put the plane on your balance machine and locate the battery in a spot where it is balanced and figure a way to install the battery.

Regards Bill
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Old 01-05-2018, 04:31 PM
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Originally Posted by Corsair Bill View Post
Gregg, I wound up cutting the area in back of the the tail wheel and made a hatch. I installed the battery under the hatch with an extension cord up the the switch. Have been flying this way for years. Put the plane on your balance machine and locate the battery in a spot where it is balanced and figure a way to install the battery.

Regards Bill
It's the same ARF model?

Can you take a picture of the hatch to show me?

What Battery pack did you choose for the plane?

Mine is the HydriMax Ultra NiMH 6.0V 2000mah Flat Pack AA Type.
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Old 01-05-2018, 05:12 PM
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Gregg, it is the ARF model and using the same Hydrimax battery. Would take a picture of my P-51 but it is in storage since we are moving. (can't wait for this PITA to be over with). With the plane upside down, I cut a trapezoidal portion of the sheeting out just behind the tail wheel. Installed the battery with Goop glue and re-inforced the sheeting with scrap balsa on both the hatch and the fuse. Used small socket head cap screws to re-attach the hatch to the fuse. I needed to locate the battery that far back because I installed a Saito 120 which is a heavy motor. BTW, this model flies great using the recommended throws. A buddy of mine at the field has the same plane, his flies great as well.

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Old 01-06-2018, 11:10 AM
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Originally Posted by Corsair Bill View Post
Gregg, it is the ARF model and using the same Hydrimax battery. Would take a picture of my P-51 but it is in storage since we are moving. (can't wait for this PITA to be over with). With the plane upside down, I cut a trapezoidal portion of the sheeting out just behind the tail wheel. Installed the battery with Goop glue and re-inforced the sheeting with scrap balsa on both the hatch and the fuse. Used small socket head cap screws to re-attach the hatch to the fuse. I needed to locate the battery that far back because I installed a Saito 120 which is a heavy motor. BTW, this model flies great using the recommended throws. A buddy of mine at the field has the same plane, his flies great as well.

Bill
Do you mean something like this?

Currently The Battery sticks up and scrapes against the elevator push rod.
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Old 01-06-2018, 01:47 PM
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Yep, thats how I installed my battery. It looks like the 5th battery cell is sticking out of the top. On your P-51, may need to go with the 4 cell 4.8v HydriMax battery so it doesn't stick out of the top.

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Old 01-06-2018, 03:18 PM
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Originally Posted by Corsair Bill View Post
Yep, thats how I installed my battery. It looks like the 5th battery cell is sticking out of the top. On your P-51, may need to go with the 4 cell 4.8v HydriMax battery so it doesn't stick out of the top.

Bill
I had a hunch that we weren't using the same pack. 6V means 5 cells. Tower might stop selling these packs. Things looked really strange when I was trying to order this one. I went to my local hobby shop and got lucky He only had one. These batteries cost me to much money to buy pack after pack. I will make this work somehow. The Balance seemed fine with this pack.

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Old 01-06-2018, 06:14 PM
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Gregory, I did the same thing with this plane. I'm using a DLE 20. Robart air retracts. 6.0v battery mounted just behind the wing saddle. I built a compartment just in front of the tail wheel for a 4.8v battery. Balanced without adding any weight. CG is 5.25 inches back from the leading edge of the wing at the fuselage. Total weight is 11 lbs. Flies good at this weight. I have over 300 flights in eight years. I reinforced the gear mounts during assembly as they were a weak point.
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Old 01-07-2018, 12:40 AM
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Originally Posted by RBean View Post
Gregory, I did the same thing with this plane. I'm using a DLE 20. Robart air retracts. 6.0v battery mounted just behind the wing saddle. I built a compartment just in front of the tail wheel for a 4.8v battery. Balanced without adding any weight. CG is 5.25 inches back from the leading edge of the wing at the fuselage. Total weight is 11 lbs. Flies good at this weight. I have over 300 flights in eight years. I reinforced the gear mounts during assembly as they were a weak point.
Why are you using two battery packs?

I don't mean to come off like I'm angry... But I am upset.... I've had nothing but bad luck with Top Flite models. This is the very last Top Flite model I build. I once tried to build the F4U Corsair kit, and It was too difficult for me. I thought that I would have better luck with the ARF version of the P-51. I have my doubts, it's already been crashed once. It wasn't damaged badly but I need to go through everything making sure things are "correct". To be clear: I built Eagle 2 kit, Super Chipmunk kit, Hog Biplane kit, Stinger 60 ARF, U Can Do 3D ARF, Zlin 526 ARF, and the Waco YMF-5D ARF. Everyone of them did exactly as they should do. Before anyone says I don't have enough experience for warbirds. Let me defuse it by saying "your right!" This will be my very last try at a warbird.
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Old 01-07-2018, 01:38 AM
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You might consider trying a P-47. Much better than a P-51 for a variety of reasons.
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Old 01-07-2018, 08:39 AM
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Originally Posted by Lifer View Post
You might consider trying a P-47. Much better than a P-51 for a variety of reasons.
Thank you for the suggestion but my mind is made up. After spending 3 years of working on a plane I thought was going to be really cool, ending up in the ground, and the very next plane doing the same thing to me. Add in the fact I have no real life help. It's not worth the time and money. I just hope I can get some good out of the model I'm currently working on. If I could boycott top flite completely I would! I feel like the company screwed me over so many ways! I can't understand how anyone defends that company. But people do! I know they DO! They must have more time, money, and better help to get through the building and learning to fly process. Judging from my experiences on the forums, it appears to me they like to act like a bunch of elitists. With comments like "Why didn't you listen to the experts" "Sounds like your lack of experience has gotten to you" These kinds of comments don't help anyone resolve issues!!!! If you feel like your in over your head, these kinds of comments make your pain worse. Which is what I think is the goal of some of those people. If your curious you should be able to do some searches on this site of some of my earlier threads. What you should find is that the manual and plans by top flite: caused me to do a lot of asking questions, and getting a lot of mixed answers. Combined with some of the negative comments. That old F4U probably needs to be entirely rebuilt. And I'm not going to give top flite any more of my time and money!

With that being said: I think I can move the support and add back some support in some other places, so that I can get the battery back there. My other thought is maybe put the battery in front of the tail wheel. At least the weight I add won't be as much. Hopefully the OS .75 can fly it. If it can't or if the model gets broken I won't be doing another warbird. Even if the model flies good, I still won't be investing in another one. Especially if it's by top flite.
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Old 01-07-2018, 09:04 AM
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Send me a P.M. and I'll give you my phone number. Perhaps I can help.
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Old 01-07-2018, 09:15 AM
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Originally Posted by Lifer View Post
Send me a P.M. and I'll give you my phone number. Perhaps I can help.
That is really kind of you! I'll send you that P.M.
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Old 01-07-2018, 10:00 AM
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Gregory, sorry the hear about your problems and frustration. It helps to have hands on in person help when you start dealing with warbirds. There are a lot of things the kits/arfs don't tell you. I alway angle the gear forward some, just by adding washers to the the real gear mount. Helps prevent nose overs. The gear mounts are usually inadequate, at least for my landings. The reasons I have two batteries is I have the old DLE 20 and experience tought me to use a 4.8v battery on the ignition. On these older ignitions, 6 volt batteries only produce more heat, no advantage. However on the receiver I wanted to use 6 volts to prevent any "brown outs" with the 2.4 system.

Also try to save weight where you can. I can see you are doing that by putting the battery in the tail. I had a couple of warbirds that were a b------ to fly because they were simply too heavy. A kit built 60 size Top Flite P-40 at 12.5 lbs (64.5" wing span) and a KMP 72" wingspan Hurricane at 14.5 lbs. The P-40 I decommissioned and sold the airframe (for static display) and the Hurricane I totaled in a landing accident.

All arfs have issues, but I have found, compared to some, Top Flite and Hanger 9 arfs to be above average with good hardware. ESMs I will call "semi-arfs" as you have to make so many changes. I think they are out of business now. Also never trust the cg stated in arf kits. Use 25% MAC. See below.
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C.G. Calculator

This form will calculate the position of a Center of Gravity (CG) on a model airplane wing as measured from the leading edge of the Root Chord. If you need to know the % of the Mean Aerodynamic Chord (MAC) for a given position of the CG you should use the Mean Aerodynamic Chord Form.
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ID:	2250245Enter Tip Chord (B): Enter Sweep Distance (S):Enter Half Span (Y):Enter %MAC Balance Point:Sweep Distance @ MAC (C) =Mean Aerodynamic Chord (MAC) =MAC Distance from Root (d) =Balance Point @ Root Chord (CG) =The EquationsC= (S(A+2B)) / (3(A+B))MAC= A-(2(A-B)(0.5A+B) / (3(A+B)))d= (2Y(0.5A+B)) / (3(A+B))CG= %MAC B.P.*(MAC) + C

I don't usually do all these calculations, just measure the wing root and mark the cg at 25% back for the leading edge. Test fly and then adjust.
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Old 01-07-2018, 10:05 AM
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I took some more pictures. I thought about moving the former forward to make more room. I removed the tail wheel cover to have a look. It does appear that it could be moved. Then I decided to get out one of my very old Nicad flat flight packs 4.8 V 600 Mah, and put it in. Just to see how it fits. Honestly I don't think I want a 4.8 flat pack back there either. It rides right on top of the elevator push rod! You could just barely get a cover over it.
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Old 01-08-2018, 12:34 PM
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Gregory,
I maidened my TF P-51 at 5 1/2", then finally moved it to 5 1/4". For me, it made for a smoother flap-down landing with less ballooning. You may not need as much tail-weight as you think. I fly mine with a (heavy) YS 1.10, battery is just behind the wing and I have about 1 1/2 oz just behind the tail-wheel.
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Old 01-08-2018, 12:50 PM
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Originally Posted by warhwk View Post
Gregory,
I maidened my TF P-51 at 5 1/2", then finally moved it to 5 1/4". For me, it made for a smoother flap-down landing with less ballooning. You may not need as much tail-weight as you think. I fly mine with a (heavy) YS 1.10, battery is just behind the wing and I have about 1 1/2 oz just behind the tail-wheel.
What Battery did you install? Do you have link or picture of it?
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Old 01-08-2018, 01:05 PM
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I used a 4c 2000 mA. I wrapped the battery in electrical tape and glued it to the side of the fuse near the back of the wing. Nothing fancy at all. Sorry no picks.
Please reconsider the 5 5/8" balance location. I can guarantee that 5 1/4" is about perfect for this plane. And this is coming from someone who likes an extreme rear CG location for my aerobatic planes. Also, this is one plane that does not really like 3 point landings. Put it on the mains and let it roll out, as any warbird should land.

Have you seen this thread?
Top Flite '.60 size' P-51D Mustang ARF: Building & Modifications
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Old 07-15-2018, 04:42 PM
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Originally I was planning on flying this plane this summer. But after I had to try and move the battery pack into the tail, I ran into so many issues that other things in my life took over. Even another R/C plane took over. I'm currently removing parts from this model and transferring them to another model. One big issue, a mistake with glue was made. While test fitting the Battery pack, I thought the glue was completely dry. It wasn't and the battery lead got glued fast. Removing it made me cut the wires and it shorted out! Got hot really fast! Then I had a terrible time finding a replacement battery pack. I tried to repair the old pack but that made the wires too stiff. Finally I found a Battery on Amazon. I was in the process of making a cover for it when other things came up and I ran out of time. I will need to buy a new engine a y harness, possibly a new radio system, and whatever else.... Another reason I may not fly this model is because when I bought this model I didn't know that there was a way train yourself for war birds. I didn't have any sport planes anymore. And I've been told that this model is not a good one for a warbird beginner. Since I'm not a member of a club I don't know of any swap meets.
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