3 blade prop for a saito 1.20

[andy watson]

I need to mount a 3 blade prop on my saito 1.20, but I'm having trouble finding one.

According to the information I have I should be looking at a 2 blade prop @ 16*6, 15*8 or 14*10. 

The rule of thumb seems to be knock either an inch off either the diameter or the pitch.  That means I should be looking at a 16*4; 15*6 or 14*8- as I want to keep the diameter as large as possible.  Unfortunately there isn't the widest selection available.

The options I have are: 14*7 or 14*9 or 16*8.

The 14's are probably OK, but a bit small for the appearance of the plane (they will barely poke out of the 4" spinner!).  Would the 16*8 be ok, or will it damage the engine/refuse to fly?  It's a scale model, so no need to wring every last drop of power out of the engine.

[Aslan]

14x7 would be perfect,you could also try a 15x6.....personaly, I would stick with the 14x7.

Although I'm not a fan of Master Airscrew,it would look more scale.

[YakMad]

If you need to wring every last drop of power, stick to two blade props either APC 15x8 or Graupner G-Sonic 15x8, keep the three bladed prop for static, Master Airsrcew props are very inefficent and noisey so stay away from them. The Saito 120 will pull a16x8  two blade prop but it will not perform badly on a 3 blade 16x8.

[Aslan]

A two blade would definitely be the way to go,and YakMad is on the button there...... But a 16x8 3 blade?? Unless it's a Master Airscrew,which are so inefficient it could work....Mmm interesting.....Yeah.

[andy watson]

well the 16*8 is a master airscrew......and I agree with both of you- less efficient, but look much more scale than a grey graupner one.

 

The again scale is relative- it should be about 20 inches diameter.

 

I might try the 16*8 though- surely 4" of spinner will reduce the load to some degree.

[Aslan]

I think generally the root length, would be more or less the same on the prop sizes we're talking about here Andy, so even with a 3" or 3 1/2" spinner the thrust would be the same...

Can't wait to see how you get on with the 16x8. Maybe you could post some Tacho. readings. 

[Martin Harris - Moderator]

Posted by andy watson on 08/12/2009 10:45:37: 

I might try the 16*8 though- surely 4" of spinner will reduce the load to some degree.

 

Personally,  I would disregard the spinner area - that part of the prop doesn't contribute to any meaningful degree.

 

 One of my 1/12 scale combat models (Me209) uses a 7" x 5" prop on a .15 and a 2 3/4" spinner - gives the impression that only the tips are poking out but there's certainly no lack of go!

[andy watson]

The problem basically comes down to trying to get a sensible balance between scale appearance and performance.

 

It would be easy to go the 2 blade prop route, but that seems a bit silly if you have just spent 2 months applying every last rivet to the airframe. 

 

I have bought a master airscrew 16*8 and will see how we go, if it's not up to the job there is the 14*7 master airscrew, or a grey 15*8 graupner I have found.

 

I guess the sensible route would be a flying prop and a static one.

[Aslan]

Just thought you may be interested in a company in Germany called Tailormadedecals. You can email him with the scale of your Stuka,and he makes up all the maintenance nomenclature for you. Really finishes off  the scale look. Got them for a 1/6 scale FW190, and they are superb. Sends them with the proper stuff for applying them to the model for around 30 quid,if I remember correctly.