Magnum 36 / Twister

[Paul Allen]

Just a quick note on the Magnum 36 XLS,I posted
a photo a few months back of my scratch built
Cardinal, which was powered by the Magnum.
Model was test flown with it and performed OK
it was then refitted into the Twister with the following
results.The motor runs around 9,800rpm with a
11x4 APC, 0.253" venturi with green Bru Line filter
uses about 3.25 oz of fuel, 11.5% Castor,11.5% Klotz
and 5% Nitro, flying conditions were trying to say the
least,39 degree's C ( over a 100 F ) hot wind,motor
ran extremely well sounded a lot like a pipe motor.
Have ran this motor in an Oriental with similiar results
so they seem to work inverted or side mounted.

[Alan Hahn]

I am surprised that a static 9800 rpm on an 11-4 prop translates into a good cruising speed. I would have thought that it would need to be up in the 11000 rpm region with such a low pitch. Oh well, if it works, who can argue! Shows how tuff it is to base things on static numbers.

[Bill Little]

Hi Alan,

It is odd, isn't it?  But with the PA 51-61 etc., we are launching around 10,000 (from what I have been told) with 4 pitch CF props.  Translates to 5.3-5.4 on 64' E-E .018s and a 57 oz. plane of around 660 squres.

We used to launch the OS 40VF at about 11,000 to get that.

I don't know.......

Bill <><

[Paul Taylor]

I have a 12x4 on my LA .40 and launch around the same RPM. Works for me.

[Paul Allen]

 
Interesting comments,when the Magnum was powering the
Oriental it ran 10,000 to 10,100 rpm and performed well.
I'am not sure what you guy's would call it but the run was
a fast 4 cycle switching to 2 cycle in level flight.
Now when the Twister was powered by the Brodak 40 with
the APC 11x4 prop it ran a ground release rpm of 9,300 to
9,400 and unloaded slightly in the air.
I think you would be hard pressed to get a better run of the
mill prop then the APC's ,although they are a little heavy.