RE: CD ScaleDesigns Sopwith Snipe build

RE: CD ScaleDesigns Sopwith Snipe build
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RE: CD ScaleDesigns Sopwith Snipe... - 5/31/2008 7:26:18 PM

abufletcher

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From: Zentsuji, JAPAN
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Now that we've worked out the CG and found the approximate amount of weight needed, it's time to figure out how to attach it to the airframe. Basically, I'm going to be adding it to the rear of the dummy ply panel. To get it as evenly distributed as possible (and as far forward) I decided to try melting the weights down into one thin plate by meliting it into an aluminum pot. This seemed to work well and produced a smooth "pancake" of lead that I can then shape and cut out.

< Message edited by abufletcher -- 5/31/2008 7:36:34 PM >

(in reply to geezeraviation)

Post #: 1576

RE: CD ScaleDesigns Sopwith Snipe ... - 5/31/2008 7:57:43 PM

abufletcher

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From: Zentsuji, JAPAN
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quote:

ORIGINAL: TFF
I figured out that the actual Spitfire's engine was around 50% of the total weight of the plane, so we are at a disadvantage from the start we have to add weight.

Exactly. As you (and Camdyson) point out the original had a pretty big chunk of metal up front. In fact, we could really think of these WWI aircraft as little more than an engine with a weather vane attached. The whole shape of the aiplane as we know it, is about adding stuff behind the engine to balance it out!

It's all just a game I play with myself. If I could cast a solid lead dummy engine, I'd think that was just the coolest thing ever and would be proud to stick that up front!

< Message edited by abufletcher -- 5/31/2008 7:58:28 PM >

(in reply to TFF)

Post #: 1577

RE: CD ScaleDesigns Sopwith Snip... - 6/1/2008 3:51:13 AM

TFF

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From: Memphis, TN, USA
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I would like to add nose weight with this http://www.littlelocos.com/home/littlelocos_003.htm

(in reply to abufletcher)

Post #: 1578

RE: CD ScaleDesigns Sopwith Snip... - 6/1/2008 6:09:27 AM

abufletcher

Posts: 5177
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From: Zentsuji, JAPAN
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Why not go whole hog!

http://ie.youtube.com/watch?v=P_-HhEfH1XQ

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Post #: 1579

RE: CD ScaleDesigns Sopwith Snip... - 6/1/2008 7:42:13 AM

abufletcher

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From: Zentsuji, JAPAN
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Here are the roughed out weights for the back of the dummy. They are still much too heavy at almost 800g (combined) but I'll need to be cutting them down in places. I melted down a fairly thick "pancake" of lead (a bit more than 1/4"

so that it would be heavy enough when cut down significantly (to about 450-500g). I'll bring them down to below a "fine tuning" weight so that I can add or subtract small weights to fine tune the CG later.

My plan is to bolt these large weights on to the ply plate. I'm still thinking of how to attach the whole thing to the firewall.

Attachments

Click to see fullsize image.

Click for fullsize

< Message edited by abufletcher -- 6/1/2008 7:49:28 AM >

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Post #: 1580

RE: CD ScaleDesigns Sopwith Snip... - 6/1/2008 9:56:14 AM

abufletcher

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From: Zentsuji, JAPAN
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I think the only reasonable way to attach this to the firewall is with lock-nuts in the firewall and then bots acting as stand-offs.

Also I'm going to try casting a lead weight that will fit exactly into the mock crankcase plate I made from the bottom of a spray can. I've cut open another can bottom to act as a mould for the lead. If Allan's right about the short arm level thing then moving this weight forward even 3/4" should help lighten the load. I'll also keep the weight as forward as possible by filing lead off the backside of the large weights.

(in reply to abufletcher)

Post #: 1581

RE: CD ScaleDesigns Sopwith Snip... - 6/1/2008 10:11:45 AM

CTDavies

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Joined: 9/1/2003
From: Weeze, GERMANY
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Abu,
I'd also think about getting one of those brass spinners as well. You can't place your weight much further forward than that.

_____________________________

"there is no Dark Side of the Moon really,
as a matter of fact it's all dark"

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Post #: 1582

RE: CD ScaleDesigns Sopwith Snip... - 6/1/2008 10:21:30 AM

abufletcher

Posts: 5177
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From: Zentsuji, JAPAN
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The information here gives the Saito 56-91 shaft size as 7x1mm that is a metric thread. Tower only seems to carry 5/16" and 1/4" Heavy Hubs.

http://members.aol.com/harryhig/ShaftSizes.htm

Actually, some of the later Snipes did have a small cone-shaped spinner the same size as the propeller hub.

< Message edited by abufletcher -- 6/1/2008 10:24:14 AM >

(in reply to CTDavies)

Post #: 1583

RE: CD ScaleDesigns Sopwith Snip... - 6/1/2008 10:29:07 AM

CTDavies

Posts: 266
Joined: 9/1/2003
From: Weeze, GERMANY
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The one I have weighs 136 gramms. It fits on my old FS 61, but I don't know if it has the shaft size you need.

_____________________________

"there is no Dark Side of the Moon really,
as a matter of fact it's all dark"

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Post #: 1584

RE: CD ScaleDesigns Sopwith Snip... - 6/1/2008 10:36:48 AM

abufletcher

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quote:

ORIGINAL: CTDavies

The one I have weighs 136 gramms. It fits on my old FS 61, but I don't know if it has the shaft size you need.

Is that an OS 61? A bit of googling indicates that the shaft is 5/16x24. How does that compare to 7x1mm? That 136g (4.8oz) might do nicely! Are you offering?

Also I just sent and email off to Harry of Harry's Heavy Hubs inquiring whether he could make a custom conical version. That would be pretty cool!

(in reply to CTDavies)

Post #: 1585

RE: CD ScaleDesigns Sopwith Snip... - 6/1/2008 10:48:16 AM

CTDavies

Posts: 266
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From: Weeze, GERMANY
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I don't think a metric thread will fit on an imperial sized one at all. If you can do some more research and if you find out that it does fit, I'll send it to you.

_____________________________

"there is no Dark Side of the Moon really,
as a matter of fact it's all dark"

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Post #: 1586

RE: CD ScaleDesigns Sopwith Snip... - 6/1/2008 10:57:41 AM

abufletcher

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quote:

ORIGINAL: CTDavies

I don't think a metric thread will fit on an imperial sized one at all. If you can do some more research and if you find out that it does fit, I'll send it to you.

Could a 5/16x 24 be retapped for 7x1mm or is this too close?

(in reply to CTDavies)

Post #: 1587

RE: CD ScaleDesigns Sopwith Snip... - 6/1/2008 1:29:08 PM

geezeraviation

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From: Houston, TX, USA
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Don 5/16 is darn near exactly (canI say that?) 8mm so I dont think it would work. A 7mmx1 requires a 15/64 drill which I have, I'll have to see if I have that size tap in my tool kit at work. What size is the prop hub and how sharp an angle does the spinner have? Do you have a picture of it you can post? I may be able to make one for you if I can find the tap, I have a small lathe, I just turned some brass wheel retainer caps for my N 28c1 in 1/4 scale and I have made my own heavy hubs before. Gotta go, were having a work party at the field today in preraration for out annual Warbird event. I'll ck back when I get home this afternoon. Later, Doc.

(in reply to abufletcher)

Post #: 1588

RE: CD ScaleDesigns Sopwith Snip... - 6/1/2008 3:51:51 PM