Symposium is up and running

April 14th, 2011

The symposium has started at It is a slow start but I am hopeful it will get moving in the next few days.

More exciting announcements about this site to come after the symposium has ended.


September 26th, 2010

I am trying to arrange an on-line symposium on this site for next year. The announcement was today and the symposium willl be on 11th to 25th April next year to give people some time to write, draw, photograph or video something. See for some more information.

I am expecting this to all end as some sort of disaster due to people failure (nobody is actually interested in it), computer failure (my system crashes), web site failure (somebody forgot to pay the electricity bill) or I go down with Smallpox the day before the symposium.

New forum

September 1st, 2010

In case you have not noticed, the forum at has been upgradedto something decent that you can register at and ask questions etc. related to human powered flight. I hope to anounce some exciting news (well, I think it is exciting) in the next month and a decent forum is part of that news.

Prop. Designer 0.9.4 released

July 28th, 2010

In case you have not noticed, the latest version of Prop Designer has been released. Generally the differences are small between this an the previous release, probably the tip losses are smaller resulting in higher power and better off-design accuracy are the main differences.

The down side is the maths is even more unstable than the previous versions and you may find results that suffer from the maths, please check for this by looking at the Re and efficiency plots.

It is up to you if you wish to update or not.

A quiet time

May 31st, 2010

There is not a lot happening on the site at the moment. I am hearing very little news about new or existing HPAs but there is some activity behind the scenes. I have not heard any news from Iron Butterfly, Betterfly or Zepherus recently. Abhilasha is being prepared for flying this year with some minor improvements.

I am working on a new version of Prop Designer, version 0.94 which now has its new maths working which results in only a slight change and most of the time is not worth worrying about. Other changes and bug fixes are being made or have already been done. I am now working on a new help file and I am hoping this will all be finished soon. Warning, my computer runs on Windows XP so the screen shots may not be exactly the same as on your computer. This is an improvement over the Windows 98 screen shots in the present help file.

The new version will also have some impact on the web site where there are references to it in the tutorial, for instance and they will be updated after the release of Prop Designer.

Not a lot of difference…

February 26th, 2010

I am in the process of updating Prop Designer and part of that is to use what is claimed to be an improved model to model the propeller blades. The model is the Adkins and Leibeck model which is claimed to be better than the Larabee and Glauert models I have been using. The models are generally similar but the Adkins and Leibeck model does not use approximations.

I have implimented the design of low induced loss designer and on first inspection there seems to be not a lot of difference between the 2 models. The results are similar enough that most users will not find  any difference worth worrying about.

I am in the process of modifying the main calculation routine and I will then move on to the off-design routine.

There are a number of other improvements I am thinking about making. If I can find the time and figure out ways to impliment the features they will be added otherwise I will release a version with only slight improvements.

Wortmann FX 63-137

February 7th, 2010

It was pointed out to me that the lift v angle and Cm v angle graphs were wrong for the FX 63-137 characteristics. For some reason I had put the wrong graphs on the page so I took the opportunity to not only correct the page but to double check the coordinates for the section.

This is where the trouble started! I scanned in what I consider the original section coordinates from “Man Powered Flight” and converted them to a .dat file format. Running them through JavaFoil to check how good they were I noticed that the results were not as good as they could be so I then used QFLR5 0.04 to check and I could get it to smooth the profile by moving the coordinates and add some more points. I chose 101 points and the output was fine as soon as I made the angle step 0.25 degrees. I could have used that section coordinates for the smoothed  version of the FX 63-137 but I didn’t. I went to the UIUC airfoil database at and checked out their versions of the FX 63-137. They are slightly different from each other which makes me think their smoothed version could be renamed FX 63-137 modified. Also on the site is a link to a report which contains what I hope is better quality coordinates for the FX 63-137 than the site itself.

Why am I checking all these various sets of coordinates for the FX 63-137? I don’t know. It is a very difficult section to build as you have to modify the trailing edge for structural reasons and the accuracy of construction with lightweight methods uses by HPAs means there are likely to be inaccuracies. As I always suggest, it is best to build a test section and try it for yourself first.

What of the New Year?

January 10th, 2010

What can we expect in the comming year in the way of human powered flight? Well, I would like to say there are new and exciting prospects on the horizon but I have not seen any. It is almost 50 years since the first true human powered flights in 1961 but most flights never get beyond the end of the runway. The world record distance is still held by Daedalus and there was only one flight across the English Channel.

The engineering is still difficult and the power souce has not improved substatially. I am not feeling optimistic about the year ahead but that is not helped by the scene of snow and ice I can see from the office window.

Review of the year

December 31st, 2009

As the year comes to an end it is customary to review the previous 12 months for highs and lows as well as look forward to the next year.

The year has generally been quiet with a few projects continuing from the previous year like Iron Butterfly and Zephyrus, University projects. Betterfly started construction in England.

The only highlight was Jesse Van Kuijk’s Abhilasha first flight of a HPA in the Netherlands.

Were there any lowlights? Perhaps the cancellation of the Japanese Birdman competition for this year and perhaps the fact it has been a quiet year due to the Recession.

I am hoping Abhilasha will be improved and there will be further flights in 2010 and other projects mentioned will be finished and fly. If the economy improves then there is hope for some more projects to be started.

Comments welcome.

Interesting site..if you are Japanese.

December 29th, 2009

I have come across a site that looks like the automatic translation of my site including this blog and even extending to other sites. I know there is interest in Japan for human powered flight and the Japanese Birdman competition. Translation looks generally good although I don’t speak or write Japanese and so I have to guess from the amount of untranslated text there is. The quality of the translation of the technical tems is likely to be low.

There are likely to be a number of links added to make sure this feature is used by Japanese visitors.