Top Flite 1/7 P-51 Build
02-07-2016, 06:16 PM
#3201
Join Date: Nov 2014
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I have one of those tail wheels sitting around but I've been hesitant to use it with some of the things I've heard about it breaking easily. I'm thinking about using the factory one due to those issues and to also save weight. I finally made my retract patterns and started sheeting the wings, I tacked the leading edge with CA and finished the rest with titebond because a burning nose and eyes doesn't allow me to sit the sheeting in properly in a short period of time haha. Here are a few pics of where I'm at with the wings as well as the fuse and tail feathers. 
02-08-2016, 07:51 AM
#3202
Which also brings up another question. Where to mount the retract servo? Again I am thinking as far forward as possible connected by pushrods to save tail weight.
Which brings up a third related question since I am at that step in the fuse. I have not used a solid wire pushrod in a pushrod tube the way the kit provides and it suggests the potential for vibration to me because of the size of the tube compared to the wire rod on a long run to the front. I lost a nice plane to elevator flutter and I am very very very sensitive to it now. I don't think the weight and balance can handle a servo mounted in the tail that would allow a shorter more solid run to the elevator. What say any of you who might have used the wire pushrod system or mounted a servo in the tail, especially with this kit?
I have questions about the counterbalance hinging on the tail surfaces too but better save that....this is getting long.
Last edited by BigTeeEldorado; 02-08-2016 at 07:57 AM.
02-08-2016, 09:20 AM
#3203
I haven't touched mine in a couple years, but went with air powered retracts. So for the tail wheel I mounted a cylinder up front to push/pull the tail wheel, but going to replace the mains with electrics, so will probably repurpose the air servo for the tail wheel.
02-08-2016, 10:15 AM
#3205
My "plan" is to use the air cylinder location for the fuel tank. I like that location so there is little change in CG as the fuel drops, it is about centered over the CG. I'll have an ignition to locate where the tank normally is and a little more weight on the nose with the DLE 20RA. How did yours balance? Do you think I could locate a full size servo in the tail?
02-08-2016, 07:50 PM
#3206
Join Date: Aug 2013
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Tony, I have made some progress.
I got the wing completely sheeted. That was not easy! I had a tough time getting the sheeting glued down along the LE. I even had my wife help. Luckily I had some debonder to redo some of the sheeting along the LE.
3 of the 4 sheets did eventually go down, but the upper, left-hand sheet DID NOT glue down to the ribs forward of the spar of ribs 3 thru 5. I didn't notice until i started some general sanding. I was pissed. I spent 3 hours debonding the CA, cutting out about 10 inches of the forward sheeting (careful not to damage the second sheet) and splicing in new sheeting. It looks ok...but i think it will show when the model is finished. I think i made the mistake of letting the sheeting stick to the spar before I had the chance to press the sheeting down on the ribs along the LE. As a result, the sheeting had a "bubble" in it.
.
The bottom is much easier for me to sheet. The top of the wing gets tricky with those compound curves of the landing gear.
Tomorrow, I'll finish the tips, ailerons and work on the sanding.
Pete
I got the wing completely sheeted. That was not easy! I had a tough time getting the sheeting glued down along the LE. I even had my wife help. Luckily I had some debonder to redo some of the sheeting along the LE.
3 of the 4 sheets did eventually go down, but the upper, left-hand sheet DID NOT glue down to the ribs forward of the spar of ribs 3 thru 5. I didn't notice until i started some general sanding. I was pissed. I spent 3 hours debonding the CA, cutting out about 10 inches of the forward sheeting (careful not to damage the second sheet) and splicing in new sheeting. It looks ok...but i think it will show when the model is finished. I think i made the mistake of letting the sheeting stick to the spar before I had the chance to press the sheeting down on the ribs along the LE. As a result, the sheeting had a "bubble" in it.
.
The bottom is much easier for me to sheet. The top of the wing gets tricky with those compound curves of the landing gear.
Tomorrow, I'll finish the tips, ailerons and work on the sanding.
Pete
02-09-2016, 06:50 AM
#3207
Thanks for the heads up. I'm feeling your pain right now as I read. Congrats on getting your wife to help though, mine usually runs when I start a critical gluing sequence. The pictures don't show anything noticeable and it sounds like you know what your doing so I'm sure you'll get it looking good.
I questioned the one big piece of sheeting when I read the booklet but glued up the 4 sheets anyway thinking I should just follow the instructions on this one. I learned a technique years back where you spread the glue and then spray kicker on the sheeting just before your ready to put it down. It immediately bonds and there is no need to hold it. The obvious drawback is, where it touches it stays and your alignment has to be spot on. I've had good luck with it but I haven't had to do compound curves much and you just mentioned compound curve and pucker'd me a little. There is A LOT to align with this wing, maybe I'll try using that technique to hold down just the area you mentioned........I don't know, I'll have to run that movie in my head a few more times but thanks again for the heads up. I won't be able to put down my sheeting for another week or so. I'm waiting on my gear to come back so I can finish that alignment for the doors.
I questioned the one big piece of sheeting when I read the booklet but glued up the 4 sheets anyway thinking I should just follow the instructions on this one. I learned a technique years back where you spread the glue and then spray kicker on the sheeting just before your ready to put it down. It immediately bonds and there is no need to hold it. The obvious drawback is, where it touches it stays and your alignment has to be spot on. I've had good luck with it but I haven't had to do compound curves much and you just mentioned compound curve and pucker'd me a little. There is A LOT to align with this wing, maybe I'll try using that technique to hold down just the area you mentioned........I don't know, I'll have to run that movie in my head a few more times but thanks again for the heads up. I won't be able to put down my sheeting for another week or so. I'm waiting on my gear to come back so I can finish that alignment for the doors.
02-10-2016, 03:41 PM
#3209
My Feedback: (13)
just reading through the updates on your guys builds, its a thread I have enjoyed reading, a note on the tail wheel retract love the mod on the steering arm I have a couple of these in use, I had the arm come loose on me the set screw just doesn't get a good bite on the wire, I finally had to use a little epoxy on it to get it to stay on my TF P-47 60 size if it comes free again I will remake a new arm otherwise its a sturdy little unit.
I also used it on my Royal FW190 with no problems at all, I think the biggest issue is repeated screwing/unscrewing the set screw it just gets loose and will not tighten down enough to get a good hold, lucky for me mine failed on a taxi test.
I also used it on my Royal FW190 with no problems at all, I think the biggest issue is repeated screwing/unscrewing the set screw it just gets loose and will not tighten down enough to get a good hold, lucky for me mine failed on a taxi test.
02-11-2016, 05:54 PM
#3211
My Feedback: (13)
that was a adventure 
here are some of the pics I took during my building process, what I did was use pen springs to drag the doors closed when I actuated the retract.
I trimmed down some 1/2A horns that are mounted on the doors slightly offset so they didn't hit each other when the retract entered into the fuse.
on the retract there is a small hole that I used to mount a ball link and used the plastic part that I trimmed down as a connector to hold the spring onto the retract body.
I then used ball links mounted on the horns to secure the springs to the doors, my original plan was to use stiff push rods but my geometry was off and the pen springs were way more flexible and gave me room to adjust the tension to get the doors to close properly.
as for the doors there hinged with small nylon hinges epoxied in place, the doors took some fitting and adjusting, I used wax paper taped to the fuse as a barrior, and wet balsa sheeting with a alcohol and water mix to form the shape taped in place over night, then I harvested the pieces and after getting one close and glued in I shaped the other side carefully adjusting them to fit on a center line, it took quite a while because of the P-47 door's compound curve and tail shape, there was allot of fitting and shaping before I could glue the other side in place, and more trimming and adjusting to get them to close tightly.
I used a pull/pull set up coupled to my rudder servo,utilizing plastic covered steel leader fed through plastic pushrod material the actual pushrod not the tube crossed in the rear of the tube.
the red pushrod guides are for the rudder and elevator I used them because they were lighter than the supplied steel control rods and were more flexible so I could push them out of the way of the retract unit.
originally my gear was all air I have since purchased electric conversions from CJet so my air tank is solely for the robart air piston actuating the tail wheel retract, I may DC that and get a retract servo for the TW and move it forward.
my problem was the CJet gear were constantly leaking and I got fed up with dealing with air lines the air tank is firmly glued in place, it may stay after I remove the lines and test the air for the tail if it doesn't leak I may just leave it as it is, the piston uses so little pressure I could fill the tank and fly all day without repressurizing it.
I was also thinking of going to a DLE-20 instead of the OS120 Pumpedd 4st but thats for another day
I trimmed down some 1/2A horns that are mounted on the doors slightly offset so they didn't hit each other when the retract entered into the fuse.
on the retract there is a small hole that I used to mount a ball link and used the plastic part that I trimmed down as a connector to hold the spring onto the retract body.
I then used ball links mounted on the horns to secure the springs to the doors, my original plan was to use stiff push rods but my geometry was off and the pen springs were way more flexible and gave me room to adjust the tension to get the doors to close properly.
as for the doors there hinged with small nylon hinges epoxied in place, the doors took some fitting and adjusting, I used wax paper taped to the fuse as a barrior, and wet balsa sheeting with a alcohol and water mix to form the shape taped in place over night, then I harvested the pieces and after getting one close and glued in I shaped the other side carefully adjusting them to fit on a center line, it took quite a while because of the P-47 door's compound curve and tail shape, there was allot of fitting and shaping before I could glue the other side in place, and more trimming and adjusting to get them to close tightly.
I used a pull/pull set up coupled to my rudder servo,utilizing plastic covered steel leader fed through plastic pushrod material the actual pushrod not the tube crossed in the rear of the tube.
the red pushrod guides are for the rudder and elevator I used them because they were lighter than the supplied steel control rods and were more flexible so I could push them out of the way of the retract unit.
originally my gear was all air I have since purchased electric conversions from CJet so my air tank is solely for the robart air piston actuating the tail wheel retract, I may DC that and get a retract servo for the TW and move it forward.
my problem was the CJet gear were constantly leaking and I got fed up with dealing with air lines the air tank is firmly glued in place, it may stay after I remove the lines and test the air for the tail if it doesn't leak I may just leave it as it is, the piston uses so little pressure I could fill the tank and fly all day without repressurizing it.
I was also thinking of going to a DLE-20 instead of the OS120 Pumpedd 4st but thats for another day
Last edited by bigtim; 02-11-2016 at 06:07 PM.
02-11-2016, 08:57 PM
#3212
Big Tim that is some nice work, I hope mine looks as good and I don't even have to deal with all those curves.
I have the steering rigged but the mechanics on the doors is still a shadow in the back of my head. Conceptually I want to go with something like you did so I don't have to use another servo. I probably won't figure it out until I get the doors mounted though. Geometry and most of the laws of physics seem to work better inside my head than they do outside my head. I need the parts and pieces to play with in the real world in order to figure out how to make it work. Which is why I haven't done the sheeting on the wing yet. I need my gear back to finish playing with those pieces before I glue.
Here is some pics on the steering rig. The way I set it up I should be able to take advantage of the additional travel in the tail wheel assembly with the modified steering arm and still not run into binding issues. This should also let me fine tune the tail wheel separate of the rudder even though they will both be run off the same servo.
https://www.youtube.com/watch?v=johAeE4OM1A
Oh by the way, that DLE 20 you mention is what I am planning on jamming into the nose on this one. It's going to be the RA version.
I have the steering rigged but the mechanics on the doors is still a shadow in the back of my head. Conceptually I want to go with something like you did so I don't have to use another servo. I probably won't figure it out until I get the doors mounted though. Geometry and most of the laws of physics seem to work better inside my head than they do outside my head. I need the parts and pieces to play with in the real world in order to figure out how to make it work. Which is why I haven't done the sheeting on the wing yet. I need my gear back to finish playing with those pieces before I glue.
Here is some pics on the steering rig. The way I set it up I should be able to take advantage of the additional travel in the tail wheel assembly with the modified steering arm and still not run into binding issues. This should also let me fine tune the tail wheel separate of the rudder even though they will both be run off the same servo.
Oh by the way, that DLE 20 you mention is what I am planning on jamming into the nose on this one. It's going to be the RA version.
Last edited by BigTeeEldorado; 02-13-2016 at 09:27 PM.
02-11-2016, 09:35 PM
#3213
My Feedback: (13)
I like the separate horn for steering the TW not sure if you need the springs mine is a little sloppy and the wires are fairly tight, I got all fancy when I did the P-47 and used EZ connectors on both ends, when I did my FW 190 I used fishing leader clamps for securing the wires to the gear and the EZ connectors at the servo arm so as the wires get loose I can do a basic adjustment at the servo thankfully no doors on a FW in the pic you can see my air piston install I also used a stiff 256 rod in a pushrod tube so it was less prone to bend when extended 
02-12-2016, 06:37 AM
#3214
I have successfully used the spring system before but admittedly on a different setup. The idea is two fold, or maybe three, obviously the springs can be adjusted to take up slack, but more important the system guards against binding especially since the travel will be set higher than the stock control arm and retracted it will bind with that much travel. Lastly it tends to guard against side force shock to the system. Like all my designs......time will tell 
02-12-2016, 10:35 AM
#3216
Like that tail door, very simple and straightforward, It's what I envisioned, but could never put it to paper. I take it that is a compression spring, so it forces the doors open while the tail wheel pulls it down when retracted. It that servo driven, or air? If servo, does it put a strain on the servo when retracted, or just locks down?
Big T, I had to add tail weight to mine, so it stands good reason that adding a servo in the tail wont hurt. Only way to know for sure is during the balancing. What you might want to try is assemble as much as you can, while still leaving access to the rear and put the plane on the rig and see where it falls. Load up the rest of the parts on the plane to see where you need weight. This is real easy to do on a Vanessa Rig, not so much on a point balancer. I do this with my planes before covering in case I need to put weight were there wont be access once covered.
One tip I learned over the years when it comes to sheeting, use Titebond on the sheet and ribs, let it dry, then iron it on. For the P-51 wng I ran into the same issue trying to glue it up and had bubbles too. When I found issues with the landing gear, I ripped most of the sheeting off, and recovered it. I run a bead on each rib, then brush a thin coat on the sheet where the ribs land, and to find that I just lay the sheet in place over the glued ribs, then brush it out about a half inch either side, then apply a little more glue to both and let it dry. Once dry I CA the leading edge together, then pull the sheet down over the ribs and take my iron to it at the highest setting. With the wing pinned down on the board, it comes out pretty straight, the hard part is getting the pins out afterwards, but I have small curved jaw pliers for that.
Big T, I had to add tail weight to mine, so it stands good reason that adding a servo in the tail wont hurt. Only way to know for sure is during the balancing. What you might want to try is assemble as much as you can, while still leaving access to the rear and put the plane on the rig and see where it falls. Load up the rest of the parts on the plane to see where you need weight. This is real easy to do on a Vanessa Rig, not so much on a point balancer. I do this with my planes before covering in case I need to put weight were there wont be access once covered.
One tip I learned over the years when it comes to sheeting, use Titebond on the sheet and ribs, let it dry, then iron it on. For the P-51 wng I ran into the same issue trying to glue it up and had bubbles too. When I found issues with the landing gear, I ripped most of the sheeting off, and recovered it. I run a bead on each rib, then brush a thin coat on the sheet where the ribs land, and to find that I just lay the sheet in place over the glued ribs, then brush it out about a half inch either side, then apply a little more glue to both and let it dry. Once dry I CA the leading edge together, then pull the sheet down over the ribs and take my iron to it at the highest setting. With the wing pinned down on the board, it comes out pretty straight, the hard part is getting the pins out afterwards, but I have small curved jaw pliers for that.
02-12-2016, 01:57 PM
#3217
My Feedback: (13)
I had to experiment with the tension on the spring to get it to close, pulling the doors shut was the biggest problem, when the gear deployed the spring tension was so great that the doors popped open with no effort at all,the pen springs had the perfect amount of bounce in them for my application, it took a couple of attempts to get them dialed in once I figured out the proper winding to place on the ball link I did a bunch of tests, once satisfied I clipped off the excess spring.
02-13-2016, 09:07 PM
#3219
acdii..If you don't mind my asking what engine did you use and how much weight did you add to the tail so I can do some weight comparisons to the DLE 20 I plan on using. I usually do exactly what you suggest by just piling the hardware where it goes as soon as I have a frame to do that with. I won't have that frame for a while and I would like to make an educated guess/decision on a tail servo or not at this point in my build.
The other thing that is TOTALLY intriguing and new to me is this iron the sheeting on thing using Titebond glue. I have used Titebond a lot in the past but I have never heard of this technique. So the heat re-activates the glue and it acts sort of like a contact adhesive would work? How soon does it bond after you remove the heat? How would you compare the finished bond to other glues like CA? I'm really tempted because this sounds like a lot more working time to help get it all aligned how you want it, that CA just does not let you have.
Big Tim Revisiting your setup and I have to say...That ball link idea is absolute genius where you connected the doors. It compensates for so many little variables that would be near impossible to get perfect with any other connection. Have the springs ever come off the ball?
Edit:
So of course I immediately go google "Iron on Titebond glue" and find this right at the top of the page....I'm that much more intrigued.
https://www.youtube.com/watch?v=TxUKc4JWBaI
The other thing that is TOTALLY intriguing and new to me is this iron the sheeting on thing using Titebond glue. I have used Titebond a lot in the past but I have never heard of this technique. So the heat re-activates the glue and it acts sort of like a contact adhesive would work? How soon does it bond after you remove the heat? How would you compare the finished bond to other glues like CA? I'm really tempted because this sounds like a lot more working time to help get it all aligned how you want it, that CA just does not let you have.
Big Tim Revisiting your setup and I have to say...That ball link idea is absolute genius where you connected the doors. It compensates for so many little variables that would be near impossible to get perfect with any other connection. Have the springs ever come off the ball?
Edit:
So of course I immediately go google "Iron on Titebond glue" and find this right at the top of the page....I'm that much more intrigued.
https://www.youtube.com/watch?v=TxUKc4JWBaI
Last edited by BigTeeEldorado; 02-13-2016 at 09:23 PM.
02-14-2016, 07:13 AM
#3220
Guys I was watching the video about polemerizing glue with heat
#1 it can only be used with 1/16 or less
#2 you don't have to use much glue
#3 the titebond that was used in the video is not the glue to use
You need some thing that's water proof when dry
#4 when the wood cools down the melted glue is hard like from a hot glue gun it's a lot of work and not worth it if it doesn't come out the way you want it and it has to be removed
#1 it can only be used with 1/16 or less
#2 you don't have to use much glue
#3 the titebond that was used in the video is not the glue to use
You need some thing that's water proof when dry
#4 when the wood cools down the melted glue is hard like from a hot glue gun it's a lot of work and not worth it if it doesn't come out the way you want it and it has to be removed
Last edited by SIX GUNS; 02-14-2016 at 07:15 AM. Reason: Spelling
02-14-2016, 07:17 AM
#3221
I will get the ARF down and take a look. I think I balanced with just the battery moved to the tail. I had a Saito 100 on it, and after doing a beautiful loop right into the ground, I had to rebuild the engine, and then found it fit my Cub perfectly, so it found a new home. In the meantime the ARF was rebuilt and a Saito 110(I think) was installed, and since the weight was nearly the same I dont think I added anymore, but I should probably balance it just to make sure.
IIRC I installed the battery, which I believe is a LIFE, up near the tail wheel. I will go pull it down later when I am down there getting my headlight together. Hit a deer on Friday and busted up the passenger light to the point it all fell out, so I glued and taped it back together so I have a light on that side at least until I can get it in for repairs. There goes $500 I don't have.
IIRC I installed the battery, which I believe is a LIFE, up near the tail wheel. I will go pull it down later when I am down there getting my headlight together. Hit a deer on Friday and busted up the passenger light to the point it all fell out, so I glued and taped it back together so I have a light on that side at least until I can get it in for repairs. There goes $500 I don't have.
02-14-2016, 07:22 AM
#3222
Guys I was watching the video about polemerizing glue with heat
#1 it can only be used with 1/16 or less
#2 you don't have to use much glue
#3 the titebond that was used in the video is not the glue to use
You need some thing that's water proof when dry
#4 when the wood cools down the melted glue is hard like from a hot glue gun it's a lot of work and not worth it if it doesn't come out the way you want it and it has to be removed
#1 it can only be used with 1/16 or less
#2 you don't have to use much glue
#3 the titebond that was used in the video is not the glue to use
You need some thing that's water proof when dry
#4 when the wood cools down the melted glue is hard like from a hot glue gun it's a lot of work and not worth it if it doesn't come out the way you want it and it has to be removed
02-14-2016, 09:32 AM
#3223
Guys I was watching the video about polemerizing glue with heat
#1 it can only be used with 1/16 or less
#2 you don't have to use much glue
#3 the titebond that was used in the video is not the glue to use
You need some thing that's water proof when dry
#4 when the wood cools down the melted glue is hard like from a hot glue gun it's a lot of work and not worth it if it doesn't come out the way you want it and it has to be removed
#1 it can only be used with 1/16 or less
#2 you don't have to use much glue
#3 the titebond that was used in the video is not the glue to use
You need some thing that's water proof when dry
#4 when the wood cools down the melted glue is hard like from a hot glue gun it's a lot of work and not worth it if it doesn't come out the way you want it and it has to be removed
Blue lid because if you wet the sheet down to go around any curves and the sheet may need to be weted down the titebond glue with the red cap won't work because the glue will melt , I found that out the hard way