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Old Jun 24, 2011, 09:33 PM
jbc
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Quote:
Originally Posted by Odysis View Post
Hey JB,
They are the retracts I've got in the Mirage
One weak point was the mounting tray for the nose wheel. The ply that came with the kit was brittle as anything. It's since been replaced with a fair bit of balsa (up to 6mm in places) and a whole lot of glass. Glass is my prefered option over carbon, as it absorbs impact a bit better, being more flexible.
The mains are solid. They're bedded in a sploog bay. Cut out the retract area, cover the retract unit with release film, fill the bay with sploog and stick the retract in. When it's all cured, the retract clicks in and out (about 0.05mm clearance either side from the release film). That gap it taken up with 5min epoxy. Doesn't stick well, so they can be removed / serviced.

The wire part of the struts are 5mm in the trunion (plenty strong!), but needed to be turned down to 3mm to fit in the struts (trailing link bits). Still strong enough I think. Works well off tarmac and gravel, just not grass. I'd need bigger wheels, but that loses the scale look. At the moment, the wheels are roughly scale size (even if the mirage doesn't have trailing link mains!)

either way, it was in the car this morning, but no-one else came out!
I'm gonna have to get a closer look next time you bring it down. Am spewin a bit that I slept in this mornin left my mobile/alarm in the other room so didn't hear it go off this mornin
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Old Jun 24, 2011, 11:08 PM
Life begins at transition
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I'll bring it in tomorrow.
Hopefully the F16 cures early enough to get some colour back on to it. All grey makes it hard to see!
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Old Jun 25, 2011, 02:22 AM
jbc
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I'll bring some coloured duct tape in case
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Old Jun 25, 2011, 02:41 AM
jbc
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On another note I was just going back and doing some calculations to work out thrust tube exit diameter for a Wemo 90mm rotor. To get 85% it has to be 65mm and to get 80% it has to be 63mm exit diameter. Now to me that seems a little on the small side but using the below formula it's what I get, anyone care to comment???

ok I don't know how to do the math symbolys on my keyboard so I'll just write it instead:

2= squared symbol

FSA= sqr root (fan radius x pi 2) - (spinner radius x pi 2) X x 80% / pi

So for a Wemo 90mm rotor it looks something like this:

FSA = sqr root (44.5mm x pi 2) - (20mm x pi 2) X x 0.8 / pi

FAS = sqr root (139.819 2) - (62.84 2) X x 0.8 / pi

FSA = sqr root (19549.352) - (3948.866) X x 0.8 / pi

FSA = sqr root (15600.486 x 0.8) / pi

FSA = sqr root (12480.388 / pi)

FSA = sqr root of 3972.1158

63mm diameter exit for 80%

OK maths class is over, but anyone care to see if I've done something wrong? just seems alot to choke it down to IMO from memory the thrust tubes you can buy from Wemotec are 75mm in diameter which according to the above formula would make them over 100% of the FSA.
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Old Jun 25, 2011, 03:19 AM
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Hey jbc, I thought it was just 80% of the 90mm... which is 72mm.
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Old Jun 25, 2011, 04:18 AM
WiggleWiggleWiggle
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I think you only use the actual swept area of the blades so you have to minus the area of the spinner in the centre. Is that right?
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Old Jun 25, 2011, 04:47 AM
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Its all here

6-Range-of-water-jet-due-to-velocity-of-Efflux-IIT-JEE-Phy.flv (14 min 0 sec)
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Old Jun 25, 2011, 04:54 AM
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Another angle on it

Back to Basics: DP Flow Measurement (7 min 29 sec)


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Old Jun 25, 2011, 05:05 AM
Life begins at transition
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jb, area of a circle is pi * radius squared, not radius times pi^2...

EDIT: My numbers...

od 89
id 40
or 44.5
ir 20
oa 6221.138852
ia 1256.637061
fsa 4964.501791
80% fsa 3971.601433
r 35.55559028
d 71.11118056



72mm makes more sense; closer to the pre-made ones. Disturbingly, this also happens to be within a bulls roar of 80% diameter as S3 said. As my math teacher always said (and I hated) - correct answer, wrong working out. 1/10.

Edit 2: Here's a quick and dirty excel spreadsheet. Just change the yellow cells. The rest are formulae. If you have q's about the meanings or working out, let me know.
Feed this data in to Stumax's thrust/efflux calculator, and you'll look like an aeroeng in no time!
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Last edited by Odysis; Jun 25, 2011 at 05:19 AM.
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Old Jun 25, 2011, 05:08 AM
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Quote:
Originally Posted by Odysis View Post
jb, area of a circle is pi * radius squared, not radius times pi^2...
So is that a Villis................. pi?
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Old Jun 25, 2011, 05:10 AM
WiggleWiggleWiggle
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Tomorrow morning is looking the goods.
@ Nitro- can you please bring that Rx. I'll bring the little motor that got fried.
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Old Jun 25, 2011, 06:38 AM
Glow 😡 no no no
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Hey Zoot

http://www.youtube.com/watch?v=sdlq2kx0-KI
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Old Jun 25, 2011, 09:37 AM
jbc
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Thanks Ody, so my working out was correct just formula was wrong cheers for the clarification SAWEEET!

Yeah Ozzi you gotta account for and remove the area of the spinner, so just blades only.

Thanks for all the input guys...even you Zoot .

Tomorrow does definitely look doable, reckon I might bring the bungee down in case the grass is long.
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Old Jun 25, 2011, 09:42 PM
WiggleWiggleWiggle
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Looks like I might have found a reason to buy a smartphone.
AR.PURSUIT - AR.DRONE VIDEO GAME (Full version) (2 min 48 sec)
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Old Jun 26, 2011, 12:08 AM
jbc
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That was cool, wouldn't mind finding out where they filmed that..all those jets in the background were friggin
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