Cheerful Curmudgeon

Making an Inspection Port

After spending much time and effort to properly create the large fuselage skins for my Bede BD-4C airplane, you would think that I would want to keep them nice and whole. You would think wrong. Two of them needed large holes cut into them. The top skin needed a hole for the vertical stabilizer’s spar and the left skin needed an inspection port. Read more ›

Posted in Bede BD-4C

Heartbleed Relief: Replace the Default SSL Certificate in Parallels Plesk Panel

Heartbleed logoIf you have a web site with an SSL certificate then you are probably affected by the Heartbleed vulnerability which popped into general visibility. If your server is vulnerable, you need to do two things:

  1. Update openssl
  2. Replace your SSL certificate (since you have to assume that the certificate’s private key has been stolen).

Anyone in possession of your private key can a) impersonate your web site; and b) decrypt all past, present, and future traffic.

One little piece of the recovery is replacing the default certificate for your control panel. If you only have one server then clicking around in the control panel is OK. But if you have a lot of servers, that will quickly drive you bonkers.

Here is a shell script which will replace the default SSL certificate for Parallels Plesk Panel. The new certificate will be valid for 1095 days (three years). It will then use the new SSL certificate to secure the Plesk Panel itself. Read more ›

Posted in Internet, Safety, Software

Bottom Fuselage Skins Bonded

Big weekend: I have bonded the first fuselage skins onto my Bede BD-4C airplane. I painted 3M Scotch-Weld #10 Contact Adhesive onto both the skin and the fuselage angles and then “just” stuck the two together. Here are a few photos. There is actually more adhesive on the plane than is visible in the pictures. The camera flash “made” much of the glue “disappear.”

Fuselage with contact cement applied to support angles.

Fuselage with contact cement applied to support angles.

Read more ›

Posted in Bede BD-4C

More Fuselage Skin

The rear part of the fuselage of the Bede BD-4C airplane that I am building is about 11 feet long. There are eight pieces of skin which cover it. The aft-most pieces are 0.016 inches thick and about 7.5 feet long. The four pieces farther forward are 0.020 inches thick about 3.5 feet long. I initially cut these to shape with a pneumatic sheet metal shear, which is basically a pair of electric scissors on steroids, and powered by compressed air instead of electricity. That gives me a rough shape like this.

Rough shape of bottom fuselage skin

Rough shape of bottom fuselage skin

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Posted in Bede BD-4C

Installing Lift Reserve

As you know, if you are a citizen of the universe, I am building a Bede BD-4C airplane and I have been writing about the process here on my blog for the last couple of years. Today I am going to write about something that few aviators, and even fewer homebuilders, write about. I am about to write about Lift Reserve.

Many people adhere to the common misconceptions about what makes airplanes fly: money. (Sorry… I couldn’t resist that one.) Many people adhere to the common misconceptions about what makes airplanes fly: a balancing of the four forces Lift-Gravity-Thrust-Drag. This is based in classical physics as taught to high school students and it is naive, to say the least. The problem with the LGTD is that it is simply incomplete. Lift Reserve is not addressed because, classically speaking, it is simply too hard to explain in a high school physics class. Read more ›

Posted in Aviation, Fun

MySQL + UTF-8 + PHP 5.3.10 + JSON = Trouble

Yesterday, I spent longer than I care to admit debugging an update to an old PHP script. It fetched a string from a MySQL database and (here’s the new part) passed the string to json_encode(). That call failed when the data included the multibyte characters ¼ or ½ or ¾. All of my attempts to remove the multibyte characters from the strings (replacing them with “1/4″ or “1/2″ or “3/4″) failed.

The problem turned out to be PHP 5.3.10′s default for the character set of the MySQL connection and the fix was easy. Explicitly set the character set to UTF-8:

Once that was set, json_encode() properly recognized the string as UTF-8 and it ran without error.

This problem will not occur with newer versions of PHP. They have the default character set as UTF-8.

Posted in Software

Progress on the Fuselage Skin

I have made a bunch of progress on the first piece of fuselage skin for my Bede BD-4C airplane. This is the piece on the top of the fuselage, at the rear. It sits under the vertical stabilizer so, no surprise, I got to cut a hole in the skin for the stabilizer’s spar to fit through. Here is a photo of the skin on the fuselage with the vertical stabilizer in place.

Bede BD-4C fuselage skin with vertical stabilizer in-place.

Bede BD-4C fuselage skin with vertical stabilizer in-place.

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Posted in Bede BD-4C

Cut the First Skin

Tonight, I screwed up my courage and made a diagonal cut along a 4 foot by 8 foot sheet of aluminum. This is the first piece of fuselage skin for my Bede BD-4C airplane.

Top, rear fuselage skin on BD-4C

Top, rear fuselage skin on BD-4C

Read more ›

Posted in Bede BD-4C

Python Singleton

I needed a singleton database class in a Python 2.7 program and wrote it this way.

I like this pattern but I realized that this is even more elegant:

It works because I do not really need the whole Database class to be a singleton. All I really want is a single database connection.

Posted in Software

Horizontal Tail on Bede BD-4C

Big day today. I attached the horizontal stabilator (horizontal tail) to my Bede BD-4C fuselage for the first time. Check out the video:

Posted in Bede BD-4C

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