I'm trying to design a speed brake that will go on the bottom of a fuselage. It is for a senior design class i'm in. I know the area and shape I need but I'm interested in how to create the hinge point between the door and the aircraft.. I've seen lots of pictures of how it should look on the outside. i.e F-86 Sabre but I'm looking more for the internal servo and hinge point mount. If anyone has any pictures or can direct me to a website with some pictures I'd greatly appreciate it. Having never designed the internal part i'm kinda stuck.

This should help...

David,

Have a quick look at my Thread, BVM T-33 build.

The T-33 has speed brake doors on the bottom of the fuz. It is hard to see in the pictures how it works but I will try and explain it.

Glued to the fuz is a basswood block about 1/2" by an 1". (Bear in mind there are two speed brake doors parallel to each other, so this is repeated on each side!).

On each side of the block is a small carbon arm glued and screwed to the side, that at the hinge end features an additional bit of carbon in a semi circle on top of the carbon arm, to give it a bit more meat. In the middle of the circle is a small hole.

Another carbon arm with a small "dog leg" also has this semi circle at the hinge end. The dog leg is close to the hinge so that as the brake opens, it does not foul the bottom of the fuz. The rest of the length of the arm is bonded to the speed brake door using a very high quality epoxy (aeropoxy in my case).

Two collets are used on a pin that goes through the two holes in the ends of the carbon arms, sandwiching that arms together.

Maybe less than a 1/3 of the way down on the arm with the dog leg, is yet again a semi circle with a hole through on the carbon arm (it is part of the arm, they are all moulded like this). This attaches to the air cylinder arm which in turn is mounted to a former immediately behind the basswood block.

Works quite well!!!

If that does not make sense or you can't visualise it let me know and i will see if I can draw it out for you or similar.

Regards,

Gazzer

Maybe give you some more to work with.

Roy Jimmy.

I'm more or less into a rugged construction, here some pics of my current project, an old Avonds DF F-15 which i'm modifying to "full scale" and dual KJ-66 turbine power. The airbrake is a selfmade carbon fiber / glass composite structure with hinge points at the scale location. The "hinge" is simply a steel wire going through the entire structure (uncut piece with overlength can be seen extending out of the fuselage in the second photo below). Bearings are simply small brass tubes epoxied into the airbrake carbon fiber "extension arms".
Take a look at the pictures....calculations show this will extend up to speeds of 130mph with the servo used (Extending 62°).

Greets

These are just what I was looking for. You guys are great!
dave

Well, this is the latest vertion....Tood, you have to improve your ideas
Not scale...but funtional [&:][&o][X(]

That isn't enough.
You need few tons of concrete with that anchore.
Tam