Complicated Question About Dropping Flaps

[marcus4hire]

Hi All:

As you might recall from my other threads, I am a novice assembling a 1/72 Academy P-51B. While it has taken me much longer than I anticipated, the build is coming along wonderful (token cockpit pic) and I don't want to mess it up.

Out of the box, the flaps were attached to the wing. I decided to try and drop them myself. With the help of the forums, I made the cuts and they are near perfect. I am very pleased.

After piddling around with this and that, I am finally to the point where I have to attach them and I am having some trouble. So far, I have attached the lower wing to the fuselage. I sanded the 'interior' of the wing to bring the visible thickness of the wing more in scale. I have also sanded the flaps. Even then, as you can see below, I don't have a lot of room to work with.

My question is, what are my options for actually attaching the flaps?? I am open to ideas and suggestions. Below are some pics of where I am at. I haven't glued anything other than the lower wing to the fuselage.

Token cockpit photo.

Here is an overview of the piece(s) I am working with. I would like the flap at 'full' extended position of 20 degrees.

Here is a poor quality photo of the trailing edge of the wing. Took it a dozen times and couldn't get it to focus right. The top has been sanded fairly thin as the thickness was out of scale. The bottom was not touched as I figured you wouldn't see it anyway. Note the distance between the top and bottom. Doesn't look like I have much room to add anything to attach them.

This is a pic of the flap, as seen from the side that will attach to the wing. As above, the top has been sanded and the bottom has not.

Overall, I am thinking of attaching a connecting piece of styrene to the top but not the bottom. This is because lack of room as well as the fact you shouldn't see the bottom as it is tucked up into the wing with flaps extended. The lack of room is also making it difficult to glue everything together, another reason for only a single piece connecting.

Tried to make it as simple as possible. Please let me know if I can clarify more. I am kind of stumped on this one.

Thanks!

 

[Crimea_River]

I usually try to glue a semi-circlular piece of plastic to the flap so that it is flush with the top and curves around like the leading edge of an airfoil. A piece of sprue is good for this. Assuming it's circular in section, cut it to length and flatten one edge. The flat edge will be glued to the front face of the flaps. Once it's glued on, sand and fill as necessary to get a nice curved leading edge on the flap. Once you have that and after plenty of trial fitting, you should be able to get a nice, tight fit in the hollow of the wing trailing edge into which the flap can be glued.

 

[marcus4hire]

Sounds like a plan.

Couple of follow ups, if that is alright.

In pic number 2 you can see my flaps taped together, flush on the trailing edge. The front edges do not meet up, Would you just leave as is gluing the sprue, then filling that part? Or sanding the edges even before attaching the sprue?

Also, I had considered your method before. What got me is that, in looking at photos, the piece connecting flap to wing seem to set underneath the wing/flap. Think of looking at a cross section cutaway, a piece of metal with the wing and flap sitting on top. Will the idea you proposed still have this look or will everything be flush (more or less)?? Not doubting you at all, just curious about your thoughts on the subject.

 

[Crimea_River]

I would fill the non parallel edge with a piece of plastic card.

As to the fitting, yes, you'll need to taper the curved edge of the sprue enough so it fits underneath the wing skin on top. The wing top has to be thinned considerably, which you said you've done and the sprue goes underneath that.

 

[marcus4hire]

Simple as that.

Thanks again!!

You have any idea how many times I asked myself "Yeah, what river in the Crimea?" before I figured it out?

 

[Crimea_River]

You got it!

 

[N4521U]

I will rty again, this morning my internet connection absolutely suuuuucked. See if this helps. Page 83 shows flaps.

Now I have just seen a sticky thread with P-51 manuals.... go figure.

 

[Airframes]

Note that the flaps were at full deployment at 47 degrees, not 20 degrees. Also, when deployed, two oval access holes are visible along the steel hinge line, which show clearly in reference photos.

 

[marcus4hire]

Thanks for the additional info, fellas.

I had looked in some manuals but could not find anything definitive on max flap extension. I came up with 20 degrees some way or the other. 47 degrees changes a lot!

The maintenance manual is very handy. Never thought of using that. I had been relying on half a dozen photo books and pilots manuals. I will remember that for future builds.

Oh, yes, I realize my cockpit has some problems. Long story that will be discussed when I unveil the completed plane, in the next year or two.

On second thought, let me ask this. I intend to model it as having freshly landed and everything still 'warm'. The landing flaps are 20 degrees. Assuming the pilot didn't raise them or otherwise fiddle with them would they still be at 20 degrees or something greater?

Sorry for the questions. Keep running into more and more details that I didn't expect!

 

[Airframes]

When parked, the flaps would be at 47 degrees. The main gear doors would also be closed, only cycling during retraction and extension of the gear. These doors did tend to droop, unevenly, as pressure bled off, and were sometimes seen fully open, although normally closed or at various degrees of droop. The rad and oil cooler shutters would also be open on the ground.

 

[copcheck]

Slightly off topic, but if that is the cockpit to your 1/72 scale P51, I can hardly wait to see the finished model.

That looks amazing!