Build Log F4U Corsair: 50" full fuse sketchup scratch PHP VIDEO

[tvcasualty]

[EDIT] 10/13/2009 Looking to do a group build of this model.
We have the following members who are going to participate:
RogueTitan
Derek_S
prunner
riivopii

I would like to add a few more names to this list, why not yours?
Parts list as follows...

Standard Equipment:

• 3 servos (I use 9gram),
• 150-200g motor
• Speed controller
• Rx
• This setup will spin a 11-12" propeller.

Building Supplies:

• Gold-n-rod push rod (or similar) for tail linkages
• Heavy thread for an aileron pull-pull setup
• At least 4 sheets of 2'x4' 1/4 Fan Fold Blue Core
• 1/16 - 1/8 light plywood for a firewall motor mount.
• Something to cut parts out with
• Something to hold it together, I use hot glue.
• It will work best to fiberglass the main wing for strenth.

Total all up weight will be targeted for no more then 1100g (40 Oz).
This post will be update as more information is available.
Projected finsih date will be late 01/2010

Origianl PDF Files available!
Check Serban's post here vector based PDFs (out of date 11/24/08, Note: Model flies but wing incidence is too steep (~3.5 degrees too steep).
Updated PDF Files here:
http://www.rcgroups.com/forums/showp...&postcount=187
PDFs to update your original plans
http://www.rcgroups.com/forums/showp...&postcount=188

Updated ver 7 SKP file found here:
http://www.rcgroups.com/forums/showp...&postcount=128

Videos here:
Vid #1
Vid #2

video on page 10

....
Stared modeling a 50 inch F4U today. Here's what I got so far, step by step. Hope to get a lot of this done this week, if I can manage to get the mess in the garage somewhat together.

Again, all based on making the model as simple as possible.
I got the plan view from http://www.voughtaircraft.com/
Converted it to a png (from GIF) and just started working.

The first step was to make the formers...

[gigelus2k3]

tv,

Curious people are waiting to see how you'll get around the wings Can the phlatprinter carve it from solid foam?

Serban

[thewz]

Originally Posted by gigelus2k3

tv,

Curious people are waiting to see how you'll get around the wings Can the phlatprinter carve it from solid foam?

Serban

One of the guys built a script to carve a 3D wing but it is very slow. The Gull wing would have to be done in multiple parts and glued together.

The best way to do this is to build it like a wooden built up wing. Ribs, spars, stringers and sheeting. All but the spars should be foam. They will most likely be CF.

[tvcasualty]

Well to tell the truth I'm gonna break some new ground on the wings here.
I'd normally just run 3 profiles of the airfoil and hot wire them out in 4 parts. but....
I got this expensive printer just collecting dust right now so I'm gonna give it my best shot on unfolding these beasts!!

This took an exceptional amount of work to get the wings to this point, and it's still going to be VERY rough getting them to come out right. And I still feel these is a lot more to do.

[thewz]

So you are going for the full ribs, spars, and sheeting then? Should work great! Nice work too by the way.

How did you get the nice airfoil? Did you draw it by hand? I can't get the oval to push or pul the way I want so I have to get the LE and apex then draw lines between them and delete the intersects.

[tvcasualty]

thewz, yeah, the plan view has 3 airfoils, I assume root, mid, and tip. Otherwise I would-a guessed.
There are all kinds of tricks to get the software to do what you want, construction lines are a good way to do it. But I try not to use the arc / circle command unless it specifically has a good (conservative) use.

A few more modeling pictures...

and then some take about the wing... So what I've done is created formers the same way I make the fuses. But instead of ending the section at each former I created tabs for the wing. The idea being I can locate the profile in the wing. Printed out a starboard wing and just finished rolling it together...

There are a few small issues. Number one, I still didn't manage to get my zero down on the phlatprinter (PHP) so my fold lines were not defines as nicely as I wanted them. This left the largest bend very difficult to manage. A few more fold lines certainly would help out. Number two I think the 3/16 offset might be a little bit much in this case as the profiles do not site square to the surfaces (by accidental design). I think 1/8 or 5/32 might have worked better. Number three, the ailerons and flaps need more work. They are impossible to fold as intended.

That being said, these is a whole lot right about this wing. It's very light, and yet fairly strong, I feel I could get away without fiberglassing the bottom. Also the angles all look to be correct! But I have yet to see how the port wing turn out in comparison.

[edit]
oops can't get UBS drive to load pic of the wing!

[gigelus2k3]

pictures, pictures, we want pictures (of the phlatprinted wing)!

[tvcasualty]

Woot! Got my SD to work!
Here's three pics of the wing.
Looks pretty good, I circled in red one possible problem area, as I want both wings to be symmetrical

[tvcasualty]

Here's a huge picture of the complete (w/ out control surfaces) wing. The port wing, (one on the right of the pic) was cut second on the PHP, and the bend line was much better since the zero worked this time... If you look closely you can see the leading edge (LE) is more crisp and looks neater. The port wing tip also sits about 1/8-1/4 inch higher then the starboard, I should be able to bend that correct.

[kwinters]

Awesome work - subscribed.

KW

[gnats82]

tvc...

Watching your build with interest. I've scratch built two corsairs (37" span) and find that the stab needs some +degrees incidence too. Considerable down trim needed otherwise.

[tvcasualty]

Originally Posted by gnats82

tvc...

Watching your build with interest. I've scratch built two corsairs (37" span) and find that the stab needs some +degrees incidence too. Considerable down trim needed otherwise.

Thanks for the heads up! I was/am concerned that the strong incidence on the wings would do just that. My 190 on maiden flight did a complete loop off the toss and I only gained control as I was frantically down trimming when it was inverted! I haven't printed the fuse as of yet, but since it's hard to say how much to give it I may wait until it flys to edit the design.

These flaps have been kicking my butt for the past hour, I'm about ready to re-print the wings, as it would save me a servo anyhow. Once I get the plans up for those who really dont want flaps I would unfold the entire wing, it would make things so much easier...

[gigelus2k3]

tv,

was the wing scored and cut using the phlatprinter?

[GreenAce92]

Dang another great build! nice job! looking great!

by the way have you ever used the Soapbox form curves tool? makes really nice curvy surfaces but only problem is unfolding.

[tvcasualty]

Serban, yes it was! Here is a pic of what it looks like unfolded...

GreenAce, Thanks man! I've used a spline tool before which works really well for shaping those parts that do not need unfolded, but for things that need to unroll, well simple is best, and sometimes they still break... Amazingly, these wings unfolded easier then the fuse!

BTW I just decided that the flaps were not worth the effort. So I'm gonna unfold another set and make another wing, this will give a good idea on the repeatability anyhow as well.