ETLB Squawk Forums — Archive

What Prop  size and pitch do I need for my V Max running a direct drive VW 1600 cc.  I have a short field for take off and landings.  Thanks guys, James

i would think a climb prop. don't know anything other than that tho.

Yes I am wanting something to pull out of the hole fast , I know I will compromise cruise speed but that is  OK with me. I just haven't fitted this engine before so was needing prop size information. 54/32 is a general suggestion but I wanted opinion from owners who have used different sizes and can advise me on the differences. Thanks James

Play with this: http://godolloairport.hu/calc/strc_eng/index.htm . You'll likely want a larger diameter prop with lower pitch than 54/32.


Edit:  Read the notes.  Especially, you will want to manually input prop efficiency (~80%) otherwise the default value is 100%.

Hi

I could only get the figures for the 1500cc engine from the samba com website.The 1600 should be similiar.

Putting max rpm of 3100 and using a 54x24 prop at 77 degree F in calculator provided by Bob.

You require 41 hp.From the graph you can see that would be possible with a 1500.

You would get a thrust of 219 lbs and a speed of 70mph.

Now all you have to see is weather you can get 3100rpm with that prop!

Thanks guys, good info... J

Quoted from JGlassFNP Thanks guys, good info... J

Thanks for being too kind!   Actually I am not sure whether the target RPM(rated rpm) is  the max static rpm or the max inflight rpm as the engine will unload once its moving .Any idea?

I was assuming in-flight RPM  because you use the 80% efficacy for that compensation rather that 100%