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Guillows B-17 Flying Fortress Conversion

Old 03-12-2010, 02:34 PM
  #151  
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Originally Posted by dumo01 View Post

I put each ESC in each nacelle behind its respective motor. I had originally planned to use 20a ESC but they were much to large to fit into the nacelle, let alone trying to fit them into the fuse. I came to the conclusion that the 20s were more than what I needed so I used 10a esc and fit much better. Possibly with some cramming it might be possible to get all 4 10 a units in the fuse. The heat generation from all 4 units in the fuse is a concern, but getting all 4 in the fuse would reduce concerns about adding wire between the battery and ESC, which is cited as cause of ESC failure. That failure mode seems to increased with the length of wire added, and typically seems to well above the 8- 10" max I was adding.
Looks like I will end up with 9 or 10 amp ESC's also. I plan on running the wiring and ESC's in the forward part of the wing and make it part of the wing build in the event of having to make changes.
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Old 03-12-2010, 03:04 PM
  #152  
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Originally Posted by dumo01 View Post

I would go ahead and cut the wire slots and runs now if I were you. Easier than trying to cut on an angle after assembly. I brought my wire runs through the back third of the wing and then forward to each ESC/ motor. Used the same wire run to go out to the servo at each aileron. I think you said you were going to use a single central servo for both ailerons so you might be able to run your wires more forward and cut down on the wire needed somewhat. It is a bit of a trick trying to manage the wire bundle while trying to glue the wing into place. Don't forget to cut a channel into the F1 on each side of the fuse.
Yes, the wings will not come off the table until all the control cables and electronics are installed. I drilled holes for the aileron cable tube and once the ESC's and wiring get here then I will cut slots in the top of the ribs. In the pictures a mark is shown of the cable run but then I realized I would come up short on cable and tube so I had to shorten the run . The cable has to make continous run from one aileron through the servo arm connector to the other aileron, the cable is 36" long. the control cable tube is there temporary for fitting. If you look close at the picture of the notch on F1 on the fuselage you can see the golden control arm connector where the cable will pass through.
I'm loving this build, it really makes you think.
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Old 03-13-2010, 12:52 AM
  #153  
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Originally Posted by park View Post
Dumo01, after looking at the last pictures you posted made me realize I ran my rudder cable under the horizontal stab., and that won't work. I re-routed it to come out of the vertical stab. Thanks !
My original intent was to run under the elevator to hide the push rod, but I just not figure a way to do that so I went above. What size push rods are you using? I used the .032 rods and needed to add an additional stabilization point to cover that long run from where it exits the fuse to where it meets the rudder to keep the rod from bowing on a push.
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Old 03-13-2010, 01:01 AM
  #154  
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Originally Posted by park View Post
Yes, the wings will not come off the table until all the control cables and electronics are installed. I drilled holes for the aileron cable tube and once the ESC's and wiring get here then I will cut slots in the top of the ribs. In the pictures a mark is shown of the cable run but then I realized I would come up short on cable and tube so I had to shorten the run . The cable has to make continous run from one aileron through the servo arm connector to the other aileron, the cable is 36" long. the control cable tube is there temporary for fitting. If you look close at the picture of the notch on F1 on the fuselage you can see the golden control arm connector where the cable will pass through.
I'm loving this build, it really makes you think.
I like the aileron push rod set up you are doing. I may need to try that at some point. All of the aircraft I have had have used dual servos so I never looked closely at how to set up the single servo method.

Agreed on enjoying the build. Trying to figure out how to add the things necessary to get it to fly to a model that was I think designed as a static display was good. Now if all works
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Old 03-13-2010, 04:10 PM
  #155  
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Originally Posted by dumo01 View Post
My original intent was to run under the elevator to hide the push rod, but I just not figure a way to do that so I went above. What size push rods are you using? I used the .032 rods and needed to add an additional stabilization point to cover that long run from where it exits the fuse to where it meets the rudder to keep the rod from bowing on a push.
I'm using a .032 push rod for the tail wheel and .032 cable for everything else. I got the idea from my MM P-38, it works well and bends good. They are all housed in yellow tubing and glued to balsa strips that are attached to fuselage formers. Here's a picture through the left waist gunners position.
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Old 03-13-2010, 04:17 PM
  #156  
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I flew my Apprentice and MM P-38 this morning with Wattflyer member Scott-p at a local schoolyard before the soccer moms started showing up. Here's a picture of Scott making a nice fly-by with his Apprentice.
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Old 03-13-2010, 04:37 PM
  #157  
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Originally Posted by park View Post
I'm using a .032 push rod for the tail wheel and .032 cable for everything else. I got the idea from my MM P-38, it works well and bends good. They are all housed in yellow tubing and glued to balsa strips that are attached to fuselage formers. Here's a picture throught the left waist gunners position.
So it looks like you are using a pull pull setup for the rudder? That should take care of any issues related to the distance of that last run before you get to the rudder per se. I was using just a single push pull rod and the distance from exiting the fuse to the rudder was too long without the extra support.
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Old 03-13-2010, 06:58 PM
  #158  
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To be honest I don't know what pull pull means :o would that be a connection on both sides of the rudder? I have just one cable going to the rudder.
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Old 03-13-2010, 08:52 PM
  #159  
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Originally Posted by park View Post
I flew my Apprentice and MM P-38 this morning with Wattflyer member Scott-p at a local schoolyard before the soccer moms started showing up. Here's a picture of Scott making a nice fly-by with his Apprentice.
It looks kinda real... good pic ken!
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Old 03-13-2010, 10:09 PM
  #160  
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Originally Posted by park View Post
To be honest I don't know what pull pull means :o would that be a connection on both sides of the rudder? I have just one cable going to the rudder.

That's what I meant. I guess I have only seen cable used in a pull pull set up. I had not realized it would be stiff enough to not bow if you were using it to push on a surface. I would think you will need to have your last glue point for the tube pretty close to the rudder, maybe similar to what I did with that last brace my push rod goes through. Will be interested to see what you do.

Nice picture of the Apprentice.
How did the build on your MM P38 compare to this build? I am looking around to decide what I want to do as a next build and have heard very good things about the MM models. They have several that look good, maybe the L4 or the Hellcat.

Also been looking twice at the plans that came out in the last issue of Model Airplane News for a Shoe string. That looks kid of neat but would be a complete scratch build, with sheeted surfaces. A little more challenging
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Old 03-13-2010, 10:36 PM
  #161  
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Originally Posted by dumo01 View Post
That's what I meant. I guess I have only seen cable used in a pull pull set up. I had not realized it would be stiff enough to not bow if you were using it to push on a surface. I would think you will need to have your last glue point for the tube pretty close to the rudder, maybe similar to what I did with that last brace my push rod goes through. Will be interested to see what you do.

Nice picture of the Apprentice.
How did the build on your MM P38 compare to this build? I am looking around to decide what I want to do as a next build and have heard very good things about the MM models. They have several that look good, maybe the L4 or the Hellcat.

Also been looking twice at the plans that came out in the last issue of Model Airplane News for a Shoe string. That looks kid of neat but would be a complete scratch build, with sheeted surfaces. A little more challenging
I like the MM models. I've just built two, the J-3 and the P-38. I would say the 38 is a medium skill level build but I think the 17 is harder. I kinda have my eye on MM's P-51
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Old 03-17-2010, 12:28 AM
  #162  
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Park and Legacy

Did you see the Warbird build thread? You guys might be able to get in on it, but I think I missed unless they will count the upcoming wing/motor tear down LOL. Oh well I have be content as a trend setter uless I decide to do another build over the summer, but I think I would rather spend the time flying. Plenty of time to spent inside building next winter
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Old 03-17-2010, 03:42 PM
  #163  
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No, I did not see that thread I'll check it out.

Was a little disapointed about my landing gear box but it will work out. Did you guys run into this problem? I install plastic parts K6 and K7 on F2 and F3 per the plans but the two K10 parts will not fit like they should. I trimmed a little off the sides (see pic) and made a modified box.
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Old 03-17-2010, 10:49 PM
  #164  
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Dumo01,

I'm getting close to ordering the electronics for the 17. You are using Heads-up RC 2712-17's right? With your props, have calulated your thrust? are you going to have enough power? Also do I need to get the motor mounts and shafts that they offer?

Thanks
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Old 03-18-2010, 01:22 AM
  #165  
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Yes that is the motor I used, with the firewall mount that they offer. Did not need to buy a separate shaft. I would drill out the firewall behind the mount so you will be able to slide the motor back further if you want.
I never got a chance to get a good measurement of the current the whole system was drawing with props running a full speed before the first motor went south on me. I had it running several time with props and it seemed like it had plenty of pull with me holding the plane. The first time I had my wattmeter installed to make measurements I had it running for a minute or so and then as I was cranking it up the motor went out so I shut it down. I do remember thinking that the current did not seem to be coming up as fast as I expected, at around half throttle I think I was seeing a current of about 12-13 amps which would be about 4 amps per motor. That would seem to roughly jive with the information on the Heads up web site:
GWS EP 6030 prop produces about 11.5 ounces of thrust at 6 amps with a pitch speed of 46 mph

if you figure that the three blade prop steps up the overall perfomance by about an inch of prop diameter. I like the looks of the GWS 5030 three blade but you might be able to bump up the thrust a little by going to a different prop. Will not be able to go much bigger as the 5030 only has about 3/8 inch clearance between the prop tip and fuse. I was planning an a number of taxi runs before I try to lift it off, and have never planned on more than scale performance. I saw an add in a magazine in the past couple of months for a B17 model someone was bringing out, about an 80 inch wingspan I think. One of their selling points was that with the motors they recommended it would have close to unlimited vertical performance. Never saw that on a B17 unless they mean vertical going down. What prop are you looking to use? I had a little trouble finding the 3 blade, found them at Caliberhobby.com.

I think your landing gear boxes do not look a lot different that what I remember mine (except yours are plastic, my kit was old enough they used wood). I had a small gap on either side of the gear assembly as well. I used a syringe to fill in the bottom of the box with epoxy, set the landing gear assembly in and got it squared up so i was happy with it and backfilled the gap around the assembly with more epxoy. Seemd to work OK. Would be nice to figure out a way to add a couple functional braces to the assembly to reduce the front to back flex of the gear on landing. The instructions show some bracing, but they glue into the bottom of the plastic nacelle, so I do not think they would add much strength.
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Old 03-18-2010, 03:05 AM
  #166  
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Originally Posted by dumo01 View Post
I saw an add in a magazine in the past couple of months for a B17 model someone was bringing out, about an 80 inch wingspan I think. One of their selling points was that with the motors they recommended it would have close to unlimited vertical performance. Never saw that on a B17 unless they mean vertical going down.

The thing I think about is, if you have enough power you can get out of trouble easier. You can still take off and fly and make it look scale just by being easy on the throttle. You never can tell when you might need it.
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Old 03-18-2010, 04:44 AM
  #167  
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Originally Posted by dumo01 View Post
Yes that is the motor I used, with the firewall mount that they offer. Did not need to buy a separate shaft. I would drill out the firewall behind the mount so you will be able to slide the motor back further if you want.
I never got a chance to get a good measurement of the current the whole system was drawing with props running a full speed before the first motor went south on me. I had it running several time with props and it seemed like it had plenty of pull with me holding the plane. The first time I had my wattmeter installed to make measurements I had it running for a minute or so and then as I was cranking it up the motor went out so I shut it down. I do remember thinking that the current did not seem to be coming up as fast as I expected, at around half throttle I think I was seeing a current of about 12-13 amps which would be about 4 amps per motor. That would seem to roughly jive with the information on the Heads up web site:
GWS EP 6030 prop produces about 11.5 ounces of thrust at 6 amps with a pitch speed of 46 mph

if you figure that the three blade prop steps up the overall perfomance by about an inch of prop diameter. I like the looks of the GWS 5030 three blade but you might be able to bump up the thrust a little by going to a different prop. Will not be able to go much bigger as the 5030 only has about 3/8 inch clearance between the prop tip and fuse. I was planning an a number of taxi runs before I try to lift it off, and have never planned on more than scale performance. I saw an add in a magazine in the past couple of months for a B17 model someone was bringing out, about an 80 inch wingspan I think. One of their selling points was that with the motors they recommended it would have close to unlimited vertical performance. Never saw that on a B17 unless they mean vertical going down. What prop are you looking to use? I had a little trouble finding the 3 blade, found them at Caliberhobby.com.

I think your landing gear boxes do not look a lot different that what I remember mine (except yours are plastic, my kit was old enough they used wood). I had a small gap on either side of the gear assembly as well. I used a syringe to fill in the bottom of the box with epoxy, set the landing gear assembly in and got it squared up so i was happy with it and backfilled the gap around the assembly with more epxoy. Seemd to work OK. Would be nice to figure out a way to add a couple functional braces to the assembly to reduce the front to back flex of the gear on landing. The instructions show some bracing, but they glue into the bottom of the plastic nacelle, so I do not think they would add much strength.
I'll probably start off with the GWS 5030 too and see how they do. Looks like the 6030's are to long, right? Wouldn't mine using a two blade prop if it gave more thrust. That's the propblem I'm having with my P-38, I got her flying but going to a two blade prop for more thrust. That's my weak area is figuring out what prop's to use.

Last edited by park; 03-18-2010 at 02:48 PM.
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Old 03-18-2010, 04:46 AM
  #168  
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Originally Posted by scott-p View Post
The thing I think about is, if you have enough power you can get out of trouble easier. You can still take off and fly and make it look scale just by being easy on the throttle. You never can tell when you might need it.
That's true. Have you cooled down after your flight Sunday?
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Old 03-18-2010, 03:07 PM
  #169  
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The left wing is not completed yet but I wanted to test fit it into the fuselage before gluing the wing rails. It fit very nice. I almost hate to glue the wings on, if something happens those rails are not coming out.

I'm using 2 1/4" Lite Flight wheels on the mains. There're a little bigger than scale but are great for roads that have a few bumps and loose gravel.

I added some balsa pieces to reinforce half ribs F2A and F3A they were a little loose fitting.
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Old 03-19-2010, 01:19 AM
  #170  
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Question,,,,,,, when you cut the leading edges out for the nacelles does ALL of rib F2 stay? and the bottom stringer (they called it a spar, that was almost a fatal error!)comes off too?

thanks
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Old 03-19-2010, 02:55 AM
  #171  
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Originally Posted by scott-p View Post
The thing I think about is, if you have enough power you can get out of trouble easier. You can still take off and fly and make it look scale just by being easy on the throttle. You never can tell when you might need it.

I agree. I think that the key to this is to get the props right, and I am not sure yet if the 5030 3 blades will develop the power or not. I think the motors should be capable of delivering a max of about 20 ounces of thrust at 10 amps for a short time according to the HURC web site info. For the 4 motor combined, that should be about 460 watts for a 35-38 ounce airplane. Unfortunately that prop used for that data will never fit on this airframe. I think the 5 inch prop will be about as big as we can use, may need to go to a deeper pitch blade to get the motor/ prop system to develop the power needed to get it to fly well. The plans suggested a 5 or six inch prop; I did not understand how they could suggest a six inch but finally it dawned on the that they were only planning on two IC engines mounted on the outboard motor points so they had the clearance to use a bigger prop.

The data on the 2712-17 says using the GWS 6030, which I think should be about the equivalent of the 5030 3 blade, says the 4 motors combined shoudl develop about 280 watts. Not sure if that will be too lite or not. I tried running the set up on Motocalc and came up with a "do not pass go, try again, this will not work"
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Old 03-19-2010, 03:14 AM
  #172  
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Originally Posted by park View Post
Question,,,,,,, when you cut the leading edges out for the nacelles does ALL of rib F2 stay? and the bottom stringer (they called it a spar, that was almost a fatal error!)comes off too?

thanks
The section of the LE you are cutting out is between F2A and F3a. F2 should still be inboard of the section of LE that is removed. I think the rib you are talking about is F3 and that should all stay intact. When you put the LE on the ribs there was the comment about not gluing F3 tightly to the LE so the section of LE could be removed. Save the chunk of LE you cut out. You will use most of it as bracing between the nacelle ribs when you get those in place. i left all the stringer intact through that process.

The wheels I used were DuBro lights 2 1/4 also. I thought they looked big also, but the wheels in the kit were 2 1/4 so...


Looks Good
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Old 03-19-2010, 03:16 AM
  #173  
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Originally Posted by Legacy View Post
I will have to take a look at it tonight. I am going to pull it out and get started on it again. My club has a Warbirds flyin in a month or so that I would like to have it ready for.
Legacy

How is yours going? Are you going to make your Warbird Fly in?
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Old 03-19-2010, 04:03 PM
  #174  
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Originally Posted by dumo01 View Post
The section of the LE you are cutting out is between F2A and F3a. F2 should still be inboard of the section of LE that is removed. I think the rib you are talking about is F3 and that should all stay intact. When you put the LE on the ribs there was the comment about not gluing F3 tightly to the LE so the section of LE could be removed. Save the chunk of LE you cut out. You will use most of it as bracing between the nacelle ribs when you get those in place. i left all the stringer intact through that process.

The wheels I used were DuBro lights 2 1/4 also. I thought they looked big also, but the wheels in the kit were 2 1/4 so...


Looks Good
Yes, F3 ! doa, got a little disoriented there!
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Old 03-19-2010, 05:20 PM
  #175  
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Ready to start shaping the LE and TE of the left wing. Then build the aileron. I thought (hope) it would be better to build the aileron last instead of half way through the wing build like the plans have you do.
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