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Author Topic: Bostonian materials  (Read 835 times)
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SP250
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« on: April 29, 2013, 06:49:18 AM »

For a 14g "Impington rules" model - is there anything that says it has to be balsa and tissue construction?
Can you build and compete with an all foam model?

John
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TimWescott
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« Reply #1 on: April 29, 2013, 12:29:49 PM »

Inneresting.  The rules that I'm looking at say "it must be built up", but that's as opposed to "a motor stick or a hollow tube with lightweight structure added".

I suspect that most contest directors would consider a box-structure fuselage out of foam to count as "built up".

The same rules say that wings can be solid, as long as they're over 1/16" thick, but that if they're open structure they must be covered.  Once again, it looks like foam would be acceptable.

The AMA publishes the official rules in the US (which isn't what I'm looking at -- I'm looking at the HipPocket rules, below).  Surely the British equivalent publishes the rules on its site -- yes?

http://www.hippocketaeronautics.com/ff_in_bostonian_rules.htm
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« Reply #2 on: April 29, 2013, 02:34:07 PM »

John,

The Impington rules are not a strict adoption of the AMA rules.
I have built foam Bostonians, ones with the 'box' laid on it' side etc. ... As long as it fits the rules on the Impington site, I assume it is fine.

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Russ Lister
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« Reply #3 on: April 29, 2013, 02:36:13 PM »

Here's an old montage of a few of the varying Bostonians I have built (these are all my own designs)

The top right 'Russki' is an all depron model
Attached files Thumbnail(s):
Re: Bostonian materials
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SP250
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« Reply #4 on: April 29, 2013, 06:10:34 PM »

Thanks Russ - I was thinking of Depron as I have yards of the stuff and I thought a Sorta Senator would be quick and easy compared to balsa & tissue.

Cheers John 
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lincoln
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« Reply #5 on: May 01, 2013, 05:58:45 AM »

Russ,

Those are all very nice, but I really like the one which appears to be based on the Jeep.

Lincoln
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« Reply #6 on: May 01, 2013, 04:04:00 PM »

Thanks Lincoln .... I called it the 'Chesty Jeep'  Roll Eyes
It struggled with directional stability unless it was flying fast .... but then I could hardly get it to turn.
Had a rapid straight line flight that took a wing out on some gym equipment and has been in a box since about 2004!

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Yak 52
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« Reply #7 on: May 01, 2013, 04:59:23 PM »

Just spoken to Gordon of IVCMAC and there's no restriction on materials at Impington.
There is a plastic only prop rule which I was unaware of!
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« Reply #8 on: May 01, 2013, 05:01:50 PM »

First time I've heard that too Jon .... the late Keith Horry used to use a balsa prop on his Sorta Korda, so I hope that this is a recent thing?
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Yak 52
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« Reply #9 on: May 01, 2013, 05:11:02 PM »

I dunno, I saw quite a few balsa props last time too Roll Eyes I have a feeling the winning model had one but I can't remember for sure...
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frash
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« Reply #10 on: May 01, 2013, 05:30:35 PM »

Yak52,

If you have to use a plastic prop at Impington, can you take an oversize Ikara prop and cut it down to 6-in diameter? This works well for indoor (US) Bostonian. It's is lighter, has more pitch and blade area, the blades are easily trimmed, felt-tip marker on both sides looks ok, and some people even carefully bend the plastic spars to adjust pitch. Some rules require a one-piece plastic prop or a one-piece carved wooden prop but I don't fly to those rules.

Fred Rash
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« Reply #11 on: May 01, 2013, 05:44:27 PM »

I'm not sure about IKARA props but I know cut down Pecks are used/allowed.
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SP250
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« Reply #12 on: May 03, 2013, 04:51:20 AM »

Just looked at the Impington rules as published on the link from the BMFA event thread http://www.ivcmac.co.uk/ivc02_events/ivc_events.html as below.....

The full rules are:
Maximum span 16 inches
Maximum wing chord 3 inches
Overall length 14 inches (thrust button to rear extremity)
Minimum weight 14 grams (half an ounce) without rubber
Maximum prop. diameter 6 inches
Capable of rise off ground (at least 2 wheels on separate u/c legs)
Fuselage must contain a box space of 1.5 x 2.5 x 3.0 inches and must have transparent front and side windows at least 1 inch square.

It does not say a plastic prop - only 6" max dia - so which is right?

Regards John
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