Archive for September, 2009

More about DAT files

Tuesday, September 29th, 2009

I hear about problems with opening DAT files but I don’t know how big a problem it is. I have written a small program that associates whatever program your system uses to open TXT files with DAT files. If anybody wants such a program I may add it to the library site or I could add a set of instructions for changing the file association. I know sometimes other programs use the DAT file extension for their own use so opening a DAT file can either show rubbish or at least text that is not in the desired format.

There must be some more exiting or at least more relevant to human powered flight to write about!

Blog and forum go live!

Sunday, September 27th, 2009

I have just uploaded the links to this blog and the forum so now I just sit back and wait for something to happen. Well… I try not to and I will be working on more content for the site. The succes of this blog and forum depend son how much you read this blog and how much you use the forum. Don’t blame other people if very little happens, add your own comments to the blog and add your own entries to the forum.

Changes

Wednesday, September 23rd, 2009

I am in the process of adding this blog and a forum to the web site. This will take a few days because of the program I use to create the site with and just normal testing to try to get it right. The main site has nearly 250 pages and they all have to be updated and checked that they are working how I want them to.

I hope visitors will take advantage of these new features.

It’s the start of the academic year and the number of hits increases from the Summer months. Generally the nuber of hits has been increasing as a result of the site being better known and adding more information which I hope is useful to some people. At the moment I get a large number of hits about the NACA 0009 aerofoil and second moment of area. Although much of the site is intended for 16 to 18 year olds, many Universities look at the site. (I know who you are) and so there are some more advanced sections.

Opening DAT files

Monday, September 21st, 2009

Because of the way Windows works, do people have problems opening DAT files? DAT files are just text files and are of the type .txt but the file extension is just renamed to .dat. I might do something about it and write a small program that adds the file association.

The quickest way to fix the problem is to right click on a .dat file in Exporer and select Properties. You can then alter the file association to Note Pad or another program that will edit text files. Be careful when saving the file that it is in text format and not some other format if you open it in Word Pad or your favorite word processor.

The DAT library

Sunday, September 20th, 2009

I am in discussions with certain people about the accuracy of the data in the DAT library. This is a section that concerns me as the data is mainly collected off the internet and it’s quality is unknown. So far I have not got any data that looks wrong to me but that is not quite the same as it is right.

I then use the DAT file to generate the page banners and use JavaFoil to generate the plots of lift against drag as well as the lift against angle and pitching moment, all information that helps to identify suitable aerofoils. If you choose to use a different program to generate these plots then you tend to end up with slightly different plots. This is a result of how they calculate the pressure and speed over the aerofoil and the results should be taken as close to what will happen in reality.

You will notice the results are for Reynolds numbers of 200,000 and above because below this value you tend to get laminar separation bubbles which the programs cannot cope with. Xfoil and so by extension XFLR5 and QFLR5 can indicade is present but even this program underestimates it’s effect.

A new bit of the site

Sunday, September 20th, 2009

Well, I’ve decided to add a blog to the site and tell the world all the¬†exiting things that are happening to the site. As always I am trying to add relevant content to the site and explain everything you need to know to start designing and building a human powered aircraft. I am also on the look-out for feedback to find out what you, the visitor to this site, would like added or explained better.

I will also be telling you about visits to HPAs and other places that might be of interest and that do not fit into other parts of the site.