Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Hawker Hunter

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Old 07-29-2004, 12:59 PM
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Dave03B
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Default Hawker Hunter

Just got me a new airframe.

Hawker hunter with air retracts, flaps etc.... was powered by a Super Tiger S-75, haven't flown it on this yet. 58" span, and a nice scale tractor prop model.

Not expecting mega speed, as its got a thick wing and f/g fuz and a dry weight excluding rx of 10.4lbs.

what prop size do you lot reckon for this engine/set up? i've had suggestion of 10x8. this thing came to me with a 12x6 on it!!


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Old 07-29-2004, 02:24 PM
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Default RE: Hawker Hunter

At 11+ lbs fueled up and ready to go... I'd stick with the 12x6... at least for the first flights... you're gonna need it.

Then if you feel it is possible at all, go to the smaller props.
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Old 07-29-2004, 03:23 PM
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Default RE: Hawker Hunter

Thanks
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Old 08-07-2004, 11:56 AM
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Default RE: Hawker Hunter

No one seems to know the CG for this model! How do i find it out?
Would it be the same CG as say, the Mick Reeves Hunter?
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Old 08-07-2004, 01:21 PM
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Default RE: Hawker Hunter

Hey,

send me a PM with your email address. I'll attach a windows based CG calculator...

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Old 08-09-2004, 09:06 AM
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Default RE: Hawker Hunter

Dave........

The CG will be the same on that as it is for about 90% of aircraft.

25-30% MAC

Measure the wing root chord... find 25% back from the LE
Measure the tip chord (inboard from the actual tip a bit) and measure 25% back from the LE
Take a stright edge between those two points. Find the mid distance.
That point too should be 25% back from the LE.
That is the CG point at Mean Aerodynaic Chord.

25% is a good place to start. CG at 1/3 chord or 33% is considered 'normal'. Depending on the model, the range can be anything from 20% to 35% (or even further back for some aircraft). Scale aircraft almost always require a forward CG to maintain better stability.

Often enough, some mfgs don't take the time to correctly document their CG locations. I ran into one this weekend with a club member with a P-40 from GSP. The folks a gsp told him the CG was at 5" at the root. The wing only has a 13" root chord on a straight taper wing. He was wondering why it kept snapping on takeoff. I move the CG up to 2.25" and it was flyable.

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Old 08-09-2004, 09:25 AM
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Default RE: Hawker Hunter

thats Bob and der_steuermann. der_steuermann I received the calculator, and the layout is what you've said there Bob. The windows based calc, you put in the values of the wing, and it gives you the CG. I will double cheque it the old fashioned way, just incase the pc slips up, or i did! btw Bob, magnum will be flying soon, if you can call it flying :-)
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Old 08-09-2004, 11:20 AM
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Default RE: Hawker Hunter

Here’s a CG-calculation which is very accurate and well proven. It is universally applicable for all:

trapezoidal wings

rectangular wings

back-swept wings

wing-only planes

You can even calculate the CG of wings consisting of multiple trapezoids.



Most important: The CG (Schwerpunkt) is always in front of the Center of Neutrality, namely 8% to 10% of distance ‘d’.

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