JBlade Propeller Design and Analysis Software

kolibri282

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João Morgado from the "Universidade da Beira Interior" in Covilhã, Portugal offers a propeller design software that is open source, comes with a nice graphical user interface and is fairly easy to use. Within about half a day I was able to define a prop (airfoil sections can be entered from xfoil) and run an analysis. I generated (a bit by guess and by golly) a 52x26 propeller with a Clark Y profile. Running it at 2900 rpm it generates 1380 N (310lb) of thrust at near zero airspeed and 600 N at 55mph. 310 lb is a value that corresponds quite well to the static thrust achieved in tests that were reported in the forum. 600 N is the thrust required which my simulation program calculates at 55 mph. The propeller absorbs a power of 42 kW (56 hp) at 0,5 m/s (static thrust)

You have to unra the rar files but I have no idea why there are 5 of them. Perhaps someone can report how they have gotten this to run. I did, but I have no idea what I did in the process...;-)

There is no example project in the bundle so I have attached my Bensen project below to get you started. There is no warranty whatsoever for the project, use at your own risk!

PS: for some reason it is currently (01/03/17; 07:20 UTC) not possible to add attachments. I'll try a bit later to add my example file
PPS: you can download the example and a screenshot from my magenta cloud storage https://www.magentacloud.de/lnk/bIRrGBCh

Password is jblade (all lower case)

I think that in this case we should post all comments to this thread. Please also post your own projects, especially when you created a high end propeller blade that gives good results.


Have fun!

https://sites.google.com/site/joaomorgado23/Home
 
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Jean Claude

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About 500 h (FW + ultra light)
Let us explain that the power decreases as the forward speed increases, because the throttle are gradually closed to keep 2900 rpm.

 

kolibri282

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The graphs in the image below belong to a series of simulations I carried out using my Bensen_4 blade and varying the initial pitch of the blade from 0 to 12 degrees (the built in twist of the blade due to the built in pitch remains the same as it is the same blade I use). You can change the pitch in the "create/edit propeller" dialog (see #3) For the last setting the power absorbed by the propeller increases at first and then decreases. There is a sort of wobble in the start of the thrust curve which might indicate that the result there is doubtful. Looking forward to your comments.

PS: It turned out that the attachment manager does not start when I press the icon above the text window (#1 under "attached Images") but it does start when I hit the button below the text window (#2 under "Attached Thumbnails"). Just in case someone has the same problem: It seems to be related to my current FireFox version which is 50.1.0. The problem does not exist if I switch my computer to linux.
 

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Jean Claude

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Centre FRANCE
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I piloted gliders C800, Bijave, C 310, airplanes Piper J3 , PA 28, Jodel D117, DR 220, Cessna 150, C
Total Flight Time
About 500 h (FW + ultra light)
Amazing, Juergen. If twelve degrees is the pitch measured at 0.75 R, it seems to me too small for an optimal efficiency, Jurgen.
Perhaps due to four blades?
 
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kolibri282

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I am sorry, Jean-Claude, that I have not been clear about this: the 12° have been added to the original blade which had an angle of about 11° at 0.75 R, so the pitch there is now about 23°. It is a sort of variable pitch propeller that is modeled here.
 

Jean Claude

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Centre FRANCE
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I piloted gliders C800, Bijave, C 310, airplanes Piper J3 , PA 28, Jodel D117, DR 220, Cessna 150, C
Total Flight Time
About 500 h (FW + ultra light)
So, if pitch is 23°, the loss of thrust to low forward speed is probably due to stalling of blades.
The power increase at first is perhaps due to the poor simulation of torque in this conditions.
Just my opinion, Juergen.

 

kolibri282

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Thank you for your input, Jean-Calude! The image below shows results from a still extended range of pitch values at the blade root. I think that the 13° and 14° results indicate that this prop is not as good for take off but is rather suited to attain higher speeds as thrust increases with speed and drops off much later than the lower pitch settings.
(Provided that your engine can deliver the horse power required to swing that prop...;-)
 

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