52 inch span B25 free plans - Page 11 - RC Groups
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Nov 16, 2006, 08:41 PM
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rhagen's Avatar
I'm sorry if I sound like I'm squawking, I just want to get it right without wasting a lot of foam recutting parts. You make it look so neat and precise Keith, but I guess that you do a lot of TLAR adjustments as you go along?? If so I'll just shut up and do the same!!

I've got a question now about the nacelles. You post two different ways of doing them in posts #7 and #81. I assume we do it as in #81. Do we tack the blocks together as described in #7, or do the 4 halves get cut separately? Is that why you mention color-coding them? I'm not clear on that from post #81.

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Nov 16, 2006, 10:04 PM
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sparks's Avatar
TLAR goes into the project a bit.
It's hard to keep things straight when I have done one and finding shortcuts with the second.
I'm also correcting scale problems and flight improvements as I go. But please don't "shut up",
If you see a stumble spot, the next guy that gets to the step might trip on it too.
Do you think I should delete the information on the first model to avoid confusion?

Nacelle. Go with post 81. it shows start to finish.
# 7 is shots of Ron's going together.

Cut the blocks separately.
Tack bond them together to be shaped. and mark the color code.
After they are shaped the inside has to be hollowed out so separate them.
Maintain the color code for a perfect match later.

Later because unless you have a big scroll saw, the nacelle wont fit and besides you cant see both sides for an accurate cut any way.
They have to be separated until the wing cut out is complete. the color code just makes it a little simple
Nov 17, 2006, 08:02 AM
Registered User
Have the book and it makes the timing look simple. I've found that it's always the simple things that can be the hardest. Anyway, I've been cutting in sections, by which I mean starting the cut and about 1/3 of the way thru I bring the wire up and out. Then I restart where I left off and go another third and cut out and away from the template. Then go back and finish the cut. Turned the power down for the cut and tried to pull harder on the large end. Not pretty but it worked.

For the removable wing, did you set it up the same as a normal 50" ic plane. Screws and blocks?

Nov 17, 2006, 09:42 AM
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My bad
Last edited by RobertV; Nov 17, 2006 at 09:45 AM. Reason: double post
Nov 17, 2006, 03:24 PM
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sparks's Avatar

1/8 ply firewalls.

Time to mount the firewalls.
Since the fuselage is in the way I had to use two boards and extend the work surface so there would be a slot for the nose to fit through..
With the plane standing on the front of the nacelles and the fuselage back 90 degrees to the table I checked for gaps. . . . . they were both canted inboard about 1/8 inch.

Once the gaps were gone I checked the length of the nacelles in relation to the fuselage.
I used the seam along the top of the fuselage to check for square and came up crooked.
That's a 1/4 inch shim under the #2 position.. I bonded the foam shim to the nacelle and sanded it to shape. Considering the slipshot way the nacelles are made and go on I don't think that's too bad. I'm sure the sanding to level it on the first step didn't help much either.

To make the firewalls I made 4 light ply discs. Two for the plane, and two for the cowl. I should have made 5 so I could try trimming the back of the motor detail the way Wade did his.
They were slightly larger than four inches.
With them attached to a bolt I turned them on the drill until they fit the cowl snug. Then drilled holes near the edge for the magnet installation later.
I used epoxy to bond the firewall to the nacelle. and found out that I should follow my own advice.
When you make the nacelles be sure to check the fronts before you glass them. Mine was a little out of round and it cost me "fix it" time. A little sanding and glass and I'll be back.
Nov 17, 2006, 05:42 PM
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rhagen's Avatar
Since we're all still talking about nacelles...

I just cut out a beautiful pair of nacelle halves, and found out they're too small!

I made sure the scale box on my nacelle sheet was 1" when I printed it out, but now find that my patterns are off:

1. The blunt end of the top view measures 4 and 1/4 inches across,

2. but the blunt end of the side view is only 3 and 1/2 inches across,

3. and the circular pattern is really an oval - 4" wide and 3 and 3/4" high.

putting my two nacelle halves together they are 4" wide, but too short at 3 and 1/2 inches I think that the end of the nacelle needs to be at least 4" x 4" so I can sand it down to a 4" diameter circle to fit the cowl?

I don't think this is a problem with my scaling of the pattern, because then they'd all be off the same, not too big and too small as they are. Can anybody else verify my measurements? I guess I'll have to modify my patterns to get a consistent 4".
Nov 17, 2006, 08:42 PM
RC 4 Life
sparks's Avatar
You are right and I'm sorry.
I printed it and just got back from Kinko's
My dimensions are very close to yours. It must have happened when I transferred the file to a Zone friendly type.
I drew it in CorelDRAW and I had a hard time turning it into a file type that the zone will accept.
I'm new at this, I can post the heck out of photos but apparently a drawing is harder. . . .for me

Once again I'm sorry for the wasted foam.
I have deleted the file from the post and will replace it when I have mastered posting drawings.
Until then check everything against the three view. ( it was scanned into the computer so it should be safe.)
Nov 18, 2006, 12:00 PM
who needs pistons?
nopistons96's Avatar


this is a thought i had before sparks posted the way he did the nacelles. all in all i think it worked well. i cant say that this was the best way to get the nacelles to fit the wing though. the top part of the nacelle that is attached to the top side of the wing is a bit delicate and must be handled and sanded carefully. i'll try to explain the way we did it the best i can.

this is the first time that any of us (me, vintauri and 57_KID) are using this foam and sparky's techniques. sparks has it down to a science and so far things are going pretty well. oh yeah, and the book helps a ton.

Nov 20, 2006, 11:14 AM
No more Screamer
57_KID's Avatar
you have learnt well grasshopper now go forth and conquer
Nov 20, 2006, 03:31 PM
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sparks's Avatar


Not much to add except good work Mike and be careful with the top section of the nacelles when you hollow them out.
Could you post the wing templates you used when you made the nacelle cuts incase someone else wants to use your method?

Not much to report on my progress, just the little details like servo installation.
Sort of boring stuff really.
The first shot is the typical hard balsa blocks cut to fit the servo. I use silicone to hold the servo in place. If I ever want the servo back I simply cut it free and remove it.
I'm going to try something different with the nose gear steering this time.
The one cable will run from the rudder to the servo then continue on to the nose gear steering control arm. Besides the cable being on the small side I don't see a reason why it wouldn't work.
Nov 21, 2006, 09:08 AM
who needs pistons?
nopistons96's Avatar
hey guys,
i hope this helps clear things up on the nacelle size. i took sparks 3 views and template drawing and redrew them in a cad type software and saved them as pdf images. if you open these they will go directly into Adobe Reader. when you hit print make sure that the scaling to the printer is "off" and they should be right on the money when they spit out. i have the rest of the templates as pdf's too. so if someone else out there is having troubles with them just let me know and i can get them posted as well. just as a reminder: these templates are sparkys not mine. the templates for the way i did the nacelles are different.
Nov 21, 2006, 01:25 PM
Registered User
Never realized that the B-25 was the design model for the DC-9. After I cut the wing slot and put the wing in, it became so plain to see.
Quess I measured the 8 inches from the wrong point.

Nov 21, 2006, 04:34 PM
RC 4 Life
sparks's Avatar
Dude, . . . .Please tell me that wing is not bonded there.
Nov 21, 2006, 07:20 PM
Registered User
No, luckily I stopped to fly it around the room before I glued the wing in. I measured from the back edge of the cockpit. Glad I saved the rib cutouts, can glue them back in and lightly fill the seam. Hope that is the biggest stupid mistake.
Nov 22, 2006, 01:14 PM
RC 4 Life
sparks's Avatar
I've had good weather the last few days so I had to get some work done on the shop.
Ma nature was trying to take it back, I found some rotting wood and had to pounce on it before the cold weather comes.

I did find time to get some stuff done on the plane though. Window frames!
This method should help out some of you. If you have a better way please post it! I'm open to anything.

I start with a sharpie pen and a flexible ruler or strip of card stock.
You will also need that full size three view that doesn't seem to be getting enlarged.

Draw a center line on the window right down the middle. This line is used to measure from to make sure the window panels are the same size.
You will also need another line across the fuselage. Make it the same way we have done several times already. I'm afraid that at the nose it has to be "Eyeballed" because of the compound curve the nose has.
Use the 3 view to locate where the panel lines go and mark them on the window.
Use transparent tape and tape off every pane individually and cut on the black line lightly.
( Packing tape will work but buy the cheap stuff, It will have less adhesion quality and you want to be able to pull it off without much of a fight.)
Measure the width of the structure between the window panes and cut a strip of tape to match the width.
Stick the strip to the windows using the black line to center the strip.
The tape strip is your guide for the Hobby knife to follow.
Use a new knife and make your cuts carefully and light.
If the strip of guide tape does not remove the window mask tape you will have to pick at it.

I know it's a pain but the results are even, aligned, and very neat.
I think it's worth the time.
BTW I've lost track totally on the build time for this project. Sorry.

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