Aircraft range calculator

You can download it from here (it is in the katix.org gforge svn):
RangeCalculator.ods

Some calculated results:

Target range = 1500 nm
Fuel consumption = 31.5 liters/h (2 x Rotax 912ULS, with economy cruise power)

[kts] [h]  [l] [kg]
Speed Endurance required Fuel liters Fuel weight
100 15 472.47 335.45
110 13.64 429.52 304.96
120 12.5 393.73 279.55
130 11.54 363.44 258.04
140 10.71 337.48 239.61
150 10 314.98 223.64
160 9.38 295.29 209.66
170 8.82 277.92 197.33
180 8.33 262.48 186.36
190 7.89 248.67 176.56
200 7.5 236.24 167.73
210 7.14 224.99 159.74
220 6.82 214.76 152.48
230 6.52 205.42 145.85
240 6.25 196.86 139.77
250 6 188.99 134.18
260 5.77 181.72 129.02
270 5.56 174.99 124.24
280 5.36 168.74 119.81
290 5.17 162.92 115.67

KS20 airfoil simulation

KS20:



Cl - Cd(low reynolds numbers also included, plus also flapped version (+10deg and +20 deg)



L/D vs. alpha:



Cm vs. Alpha:



Cl - alpha:



Printable profile picture of KS20 (black on white background):

    QFLR5_v.0001

 Calculated polar for: KS20

 1 1 Reynolds number fixed          Mach number fixed         

 xtrf =   1.000 (top)        1.000 (bottom)
 Mach =   0.270     Re =     5.000 e 6     Ncrit =   9.000

  alpha     CL        CD       CDp       CM    Top Xtr Bot Xtr   Cpmin    Chinge    XCp    
 ------- -------- --------- --------- -------- ------- ------- -------- --------- ---------
  -2.500   0.0172   0.00639   0.00156  -0.0630  0.5734  0.1263  -0.9628   0.0000   3.9974
  -2.000   0.0779   0.00594   0.00135  -0.0638  0.5687  0.2065  -0.7727   0.0000   1.0832
  -1.500   0.1376   0.00529   0.00111  -0.0647  0.5613  0.3515  -0.6885   0.0000   0.7246
  -1.000   0.1985   0.00466   0.00091  -0.0657  0.5560  0.4943  -0.7241   0.0000   0.5818
  -0.500   0.2604   0.00434   0.00082  -0.0667  0.5474  0.5909  -0.7638   0.0000   0.5048
   0.000   0.3235   0.00430   0.00084  -0.0677  0.5380  0.6224  -0.8063   0.0000   0.4565
   0.500   0.3863   0.00438   0.00088  -0.0686  0.5260  0.6346  -0.8489   0.0000   0.4238
   1.000   0.4491   0.00445   0.00094  -0.0696  0.5127  0.6478  -0.8954   0.0000   0.4002
   1.500   0.5115   0.00461   0.00102  -0.0704  0.4945  0.6510  -0.9563   0.0000   0.3823
   2.000   0.5732   0.00475   0.00111  -0.0712  0.4723  0.6587  -1.0304   0.0000   0.3682
   2.500   0.6344   0.00497   0.00124  -0.0719  0.4472  0.6628  -1.1188   0.0000   0.3567
   3.000   0.6941   0.00529   0.00142  -0.0723  0.4114  0.6656  -1.2143   0.0000   0.3470
   3.500   0.7516   0.00577   0.00168  -0.0724  0.3616  0.6675  -1.3096   0.0000   0.3385
   4.000   0.8098   0.00619   0.00194  -0.0726  0.3230  0.6691  -1.4113   0.0000   0.3313
   4.500   0.8664   0.00670   0.00226  -0.0725  0.2804  0.6702  -1.5275   0.0000   0.3247
   5.000   0.9229   0.00719   0.00260  -0.0724  0.2437  0.6718  -1.6463   0.0000   0.3189

KS20.dat Airfoil file for QFLR5, XFLR5 or Xfoil

QFLR5 Experiment: KSLaminar1 airfoil

KSLaminar1.dat
Simulated polar




KSLaminar2.dat

Simulations: Althaus AH 94-145 vs. AH 95-160

AH-94-145:


AH-95-160:


AH-94-145-vs-95-160:


AH 94-145 simulated ailerons, 70% chord: neutral, -10, +10 deg, mach 0.27 Re 4.5M cruise:

Interesting BWB links

www.aoe.vt.edu/research/groups/bwb/papers/TheBWBAircraft.pdf
http://silentaircraft.org/object/download/1931/doc/AIAA-2006-241-725.pdf">silentaircraft.org/object/download/1931/doc/AIAA-2006-241-725.pdf
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050182126_2005180630.pdf">ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050182126_2005180630.pdf
http://www.onera.fr/daap/ailes-volantes/aerodynamic-optimization-of-subsonic-flying-wing-configurations.pdf">www.onera.fr/daap/ailes-volantes/aerodynamic-optimization-of-subsonic-flying-wing-configurations.pdf
silentaircraft.org/object/download/1945/doc/AIAA-2007-453-759.pdf">silentaircraft.org/object/download/1945/doc/AIAA-2007-453-759.pdf

Gforge site for open source aircraft projects

Our gforge site can host in addition to software projects, also now open source aircraft projects. If you are interested in open source aircraft idea, feel free to join the forces at:

http://gforge.katix.org/gf/

I have setted up two my open source airplane projects there (they don't have much yet, but one has to start from somewhere, right?). So if you are interested in joining one of these existing projects, or you have a promising own project which you would like to share with other people, here is your chance. Register yourself and propose a project. I am the admin and approving you and your project proposals.

The motivation to join could be to get some fame. In the software field, open source developers are at the top of the ranking scale. This could be the case in the other fields too. You can make sure that you don't miss the train by joining and contributing to projects or by creating and sharing your own projects with everybody. Also here is your chance to collaborate and get results. Getting things done with large number of eyes looking after the same thing is more likely than everybody doing their things alone.

The site requires approval from site admins, so please make sure you describe your project in enough detail to get it approved. We do approve potential projects.

ZyggerDesigner gforge project (svn repository) is now up

Kate setted up gforge on our server, so I decided to put my conceptual design tool to a subversion repository. You can find it here:

http://gforge.katix.org/gf/project/zdesigner/

Contributions to the software is very welcome. You can register to the Katix gforge and join the project if you think you can contribute. I am looking for aeronautical engineers and students to help with the software development. There may be some equations which have errors. You can help with pointing them out. The bug tracker should be used for that purpose.

Also some extra eyes reviewing the code (it is currently quite quickly hacked together) would be helpful, if you are not specialized in aircraft conceptual design, but you are good with C++ and Qt and you have too much time, feel free to join and start filing bugs about bad code. If you have even more time, feel free to write and suggest patches that fixes the issues. I am not looking for comments about indentation (if I see that kind of bugs too often, I will resolve them as invalid) etc., but rather memory leaks, something done really wrong with Qt - real issues in other words.

The code is licensed under GPL version 3 or any later version -license.

Anonymous svn access to the repository (without commit privileges):

svn checkout http://katix.org/svn/zdesigner/trunk zdesigner

NLF215F considerations, Cl for different conditions

My earlier post about the NLF215F simulations with XFLR5, the related parameters for aircraft would be in the use case (one iteration of thinking):

- low altitude cruise:
* altitude = 12000 ft
* W/S = 22 lbs/sqft
* Clcruise = 0.41
* NLF215F flap in the -10 degrees position, gap seals closed

- high altitude cruise:
* altitude = 36000 ft
* W/S = 22 lbs/sqft
* Clcruise = 0.96
* NLF215F flap in the 0 degree position, gap seals closed

- extreme high altitude cruise
* some fuel burned already -> W/S reduced to 21 lbs/sqft
* altitude = 46000 ft
* W/S = 21 lbs/sqft
* Clcruise = 1.48
* NLF215F flap in the 0 degrees position, gap seals closed

- approach
* 1 slot open
* W/S = 15 lbs/sqft
* altitude = 1000 ft
* Cl = 1.1, V = 75 kts (at gross weight, W/S 22 lbs/sqft)
* Cl = 1.1, V = 65 kts (when fuel tanks nearly empty, W/S 15 lbs/sqft)
* NLF215F flap in the +10 degrees position, 1 slot open

- landing
* 2 slots open

NACA Technical note 2149

Investigation of boundary-layer control to improve the lift and drag characteristics of the NACA 65-2 415 airfoil section with double slotted and plain flaps

Some analysis for NLF215F

Above picture as full size 2560x1600

Some NLF215F polars in text format

NLF vs. turbulent

I ran some simulations for different airfoils in the same condition:
- cruise at medium low altitude, Cl = 0.4, speed = 0.26 mach, Re = 4000000, wing loading >= 20 lbs/sqft.

I first simulated a large number of different airfoils, but finally only picked the couple of NACAs and the NLF215F with -10 degree negative cruise flap and without.

The NLF215F has a clearly better overall performance all over the Cl range what it comes to Cd. Also the pitching moment of this airfoil becomes low when the cruise flap is at -10 degrees.

How to use XFLR5 in Linux

The XLFR5 is a easier to use interface built on top of the X-foil engine. The X-foil also features wing and whole airplane analysis functions.

The downside of the program has been that is only available for Windows. However, it can be run nowadays in Linux without porting the program to e.g. Qt (which is a big task), so in the mean time before any cross-platform version appears, you can live with the wine in Linux environment:

- Make sure your wine version is a pretty recent one, version greater than 1.0.

I am using the Ubuntu Intrepid version. apt-cache policy wine reports the following:
wine:
Installed: 1.0.1-0ubuntu2
Candidate: 1.0.1-0ubuntu2
Version table:
*** 1.0.1-0ubuntu2 0
500 http://archive.ubuntu.com intrepid/universe Packages
100 /var/lib/dpkg/status
W: Duplicate sources.list entry http://archive.ubuntu.com intrepid/universe Packages (/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_intrepid_universe_binary-i386_Packages)
W: Duplicate sources.list entry http://archive.ubuntu.com intrepid/multiverse Packages (/var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_intrepid_multiverse_binary-i386_Packages)

If you are running the latest stable Ubuntu (Intrepid - 8.10), you can use the Ubuntu supplied one and it will work fine with XFLR5. However, if you are running Ubuntu Hardy or some other distro that does not have the post-1.0 version available, you can install it from winehq repository. For debian based distros like Ubuntu, the instructions can be found from here:

http://www.winehq.org/download/deb

Our living room computer is not yet updated and it is still running the older Hardy. I updated the wine by adding the following line to /etc/apt/sources.list:

deb http://wine.budgetdedicated.com/apt hardy main #WineHQ - Ubuntu 8.04 "Hardy Heron"

Then I did apt-get update and apt-get install wine

The new version of wine got installed and the XFLR5 started working fine.

Download the XFLR5 from here:
http://xflr5.sourceforge.net/xflr5.htm

Go to download page and click download. At the time of writing this, the 4.15 was the latest version.

Download the zip file XFLR5_v415.zip to a new subfolder into your home directory, because the zip file does not contain directories and when you unzip it, if you was in your home directory, you get the package contents directly there which messes up your home with lots of unnecessary files.

Run the XFLR5_Setup.exe by typing on a terminal:

wine ./XFLR5_Setup.exe

The setup runs and finishes.

After this you can notice that a new entry appeared to your Applications menu (in Gnome):
Applications - Wine
Select submenu Programs, and there XFLR5 and on that submenu XFLR5.
XFLR5 should now start successfully.

It works on my computer without problems now.

First attempt on airfoil design

I created these:

KaroliinaNLF1016.dat
KaroliinaNLF1016F-5.dat

X-foil is predicting for KaroliinaNLF1016F-5 (-5 degrees cruise flap for low altitude) exactly what I was looking for. The KaroliinaNLF1016 is decambered and a bit thickened (16%) version of NASA NLF1015. According to quick analysis, laminar bucket has same shape as NLF1015 has, L/D and minimum Cd is the same, but it has been lowered to a bit lower Cl and also the useful Cl is a bit lower than on NLF1015. However, this way, the unacceptable cruise performance at low altitude theoretically gets acceptable. I need to experiment more and try out with different Re numbers. I was testing at only Re = 1000000 since that is where I was targeting the high altitude cruise. However, the Re is a lot higher at low altitude, gets easily to 5000000, so I will need to try more analysis on the airfoil tomorrow.

Aircraft and airfoil design programs

This page contains a quite good list of aircraft design and airfoil programs

Clouds all over the world

Wanna see the current cloud situation?
I accidentally found this, it is pretty cool site, satellite imagery is updated daily and it covers the whole Earth:

http://www.flashearth.com/

HALE airfoil

DESIGN OF AN AIRFOIL FOR
A HIGH-ALTITUDE, LONG-ENDURANCE REMOTELY PILOTED VEHICLE
http://www.rollinghillsresearch.com/Aero_Research/Files/AIAA-2003-0211_NLFairfoil.pdf

NLF1015 coordinates
NLF1015 picture
More accurate picture of NLF1015