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Help! put four blade prop on spitfire mk IX 1100mm drawing to many amps

#1
thee four blade is drawing to many amps (45) on a 30 amp esc, i have a 40 amp but is not enough any sugestions to lower the amps would be great cheers thomas
 

CarolineTyler

Well-known member
#2
thee four blade is drawing to many amps (45) on a 30 amp esc, i have a 40 amp but is not enough any sugestions to lower the amps would be great cheers thomas
Smaller diameter prop would be the best thing. The most efficient prop would be a balanced single blade and as the number of blades go up the drag and thrust increases but with each blade the drag losses increases a bit more than the thrust increase.
 

Hai-Lee

Old and Bold RC PILOT
#3
If you are stuck with the prop then you will need to reduce the cell count on the battery.

If you have access to alternate props then you need to reduce either the Diameter, the Pitch or the number of blades. There are no other real options without changing the ESC and possibly the motor!

Have fun!
 
#4
Smaller diameter prop would be the best thing. The most efficient prop would be a balanced single blade and as the number of blades go up the drag and thrust increases but with each blade the drag losses increases a bit more than the thrust increase.
ok thanks for the help by the way its 4 blade to make the plane scale
 
#5
If you are stuck with the prop then you will need to reduce the cell count on the battery.

If you have access to alternate props then you need to reduce either the Diameter, the Pitch or the number of blades. There are no other real options without changing the ESC and possibly the motor!

Have fun!
what 50 amp esc's do you suggest (what brand)
 

kilroy07

Well-known member
#8
Yea, I was going to caution you about just slapping on a bigger ESC. While the ESC might handle the extra amperage, your motor might not (I have a bit of experience “stressing” motors beyond their limits.) 😉

I believe early spits had a three bladed prop... 🤔
(I’m with you... I cring when I see a P-51 with a 2 bladed prop.)
 
#9
I believe you are referring to running a 4 blade on the 1.1m Parzone Spitfire MkIX? The preferred route for doing this is to use the old eflite 4 blade from the 1.1m P-51: https://www.gravesrc.com/e-flite-4-blade-propeller-9-8-x-6.html . This has a lower pitch (6 vs 8) than most of the other similarly sized FMS/Eflite/Hobbyking 4 blades. In fact, the now discontinued eflite P-47 used the same power system as the Spitfire (950kv 15-sized motor) with this exact same propeller: https://www.horizonhobby.com/produc...ind-n-fly/p-47d-thunderbolt-bnf-basic-efl6850 . This should easily drop your max current back below 40A and put it within the limits of the power system.
 

quorneng

Well-known member
#10
As others have said the prop, motor, ESC and the size and number of cells in the battery have to be considered together and each item has to be kept within their individual specifications. Significantly change one can lead to problems with the others.
If you want to turn a scale diameter 4 blade prop your first requirement will be a motor with a much lower kV. This will run a lower RPM for the same voltage and should draw something like the same as the amps as current. You will then find although it has the same total power the plane's performance will be lower as a 4 blade is less efficient than 2!

By the way the Spit Mk1 started out with a fixed pitch two blade prop, then 3, then 4, then 5 and finally 6 (two 3s contra rotating). Take your pick!