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Engine for PB Models Tornado


Tony H
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Hi All,

 

I have a dilemma, I am building a PB Models Tornado at the moment and have and Irvine 53 and a Irvine 61. The instructions recommend a 60 size engine (probably based on 70s less powerful engines).

 

The 61 engine seems fairly large for the size of the plane being 62" wingspan (wing area 625sq.in) and about 6-6.5lb. 

 

I am debating about putting the Irvine 53 in because it would be less thirsty and weighs 168g less. Also from what I have seen the power is pretty much the same. Cloud models say a good 55-60 engine will fly the plane.

 

If I compare the plane to a modern Seagull Models ARTF PT-19 Fairchild which is designed for a 46-52 IC engine, it has a 61.4in wingspan (604.5sq.in wing area) and an overall weight of 6.4lbs. 

 

So I would assume the plane will fly quite well on a Irvine 53 and not be underpowered. What do you think?

 

I am building the retract version so it will be on the heavier estimated weight of 6.5lb.

 

 

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I think your assumption that 70's engines were less powerful ( than later engines)  is probably wrong for .61 two strokes of the top makes.   I would say try to use a decent .61 if possible.  

As the model was designed for a .61 then the lighter .53 will probably need lead unless you reduce the tail end somehow.

Edited by kc
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Tony providing you can keep it down close to 6Lb then the Irvine 53 should be adequate. If you take a period contemporary schnurle-ported engine (to the Tornado) an HP61 this weighed 528g with silencer against the Irvine 53 at 516g with extended quiet silencer.

The HP61 was rated at a maximum power of 1.28BHP against the claimed figure of 1.7BHP for the Irvine 53.

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