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Clean Sweep!

...with swept-forward wings and a T-tail!

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Tim Hooper04/05/2011 23:05:32
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Evenin' all!
 
This is probably very premature, but I've had this idea knocking around in what's left of my brain for a little while now.
 
Trouble is, it's not scale. Scale is easy - the full-sized designer has done all the hard work, whereas a non-scale sports model has to be done from scratch. Truth is, I've only ever designed one non-scale model before, so I'm a bit nervous.
 
So here we go. I fancy something a bit whizzy, but employing a swept-forward wing, some fancy down-turned Hoehner wing tips, and a T-tail. So out came the graph paper and a stub of a pencil.
 
 
Doesn't look to bad , I was encouraged to quickly build a 17" chuckie to see if my CG calcs were in the ballpark....

I set the CG at 25% MAC, and suspended the chuckie from a wire hook whilst I added a little bit of nose weight.


So far, I'm delighted to report that the little chuckie flies well!


tim

Edited By Tim Hooper on 04/05/2011 23:08:05

Tom Wright 205/05/2011 00:13:28
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Now that does look good Tim how about making this one say 60 in span with a wing loading of no more than 20 oz per sq ft ? the modest wing tapper and dihedral could result in a really nice sports design that is different and easy to fly ,what do you have in mind EP or the dirty option? Oh glad to see its got an elev rather than the tempting all moving alternative.
 
Tom.

Edited By tom wright 2 on 05/05/2011 00:17:40

Stephen Jones05/05/2011 00:30:16
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Hi tim
 
Get it done it looks good too me .
leccyflyer05/05/2011 09:18:21
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Looks brilliant Tim - positively unique!
 
What sort of size were you thinking of?
Simon Chaddock05/05/2011 10:10:48
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Hi Tim
Starting literally from a blank sheet of paper is an interesting exercise.

I like your approach of building a 'chuckie'. In an unusual design it certainly allows you to get an idea of the CofG.

Was there any reason for the sweep forward?
From a structural point of view it needs careful design to ensure that any flexing under load does not increase the angle of attack towards the tips. This can be a receipt for disaster in a high G situation!
 
You would never think you put the span in the title!

Edited By Simon Chaddock on 05/05/2011 10:13:53

Danny Fenton05/05/2011 10:17:08
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Looks great Tim, nice lines and looks well proportioned if a little short on tail moment. 60" with a 1kw motor should make it shift.......... You could design some fancy Hoehner tipped bicycle clips to go with it

Should be fun well done for having a go

Cheers
Danny
Tim Hooper05/05/2011 14:01:24
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Cheers lads!
 
Simon, I hear you on the inherent wing flex issues. I've done a bit of research (read 'Wiki') on the subject, so I'm going to build in a couple of degrees of washout. Hopefully I can build a stiff enough wing for it not to be needed though!
 
The forward sweep is for pure aesthetics really, but it tends to drag the apparent CG forwards, so the long nose should help to negate the need for any ballast up front. That's the theory anyway!
 

Tom, I'm sort of partial to the 48" span idea. I have my 'known' 450 watt, 3S power train in mind (and in stock). Not only that but 48" is about right for any freebie plan later on....
 
tim
Chris Bott - Moderator05/05/2011 15:15:18
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Looks lovely Tim, I like the 48" size.
The nose cheeks look like they will set it off a treat too.
How about a V tail? (only joking the T seems to suit it).
 
Cheers
Chris
leccyflyer05/05/2011 16:15:39
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1098 forum posts
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48" is perfect Tim with that power train in mind. All you need to do now is to educate the readers into actually reading the thread title properly!
Danny Fenton05/05/2011 16:25:59
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Tom Wright 205/05/2011 16:52:52
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OK Leccy i should have gone to spec-savers. .
leccyflyer05/05/2011 18:30:56
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I actually meant ME guys, not you!
Tim Hooper05/05/2011 19:33:59
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Posted by leccyflyer on 05/05/2011 16:15:39:
48" is perfect Tim with that power train in mind. All you need to do now is to educate the readers into actually reading the thread title properly!
 
So, that's an hour in the Naughty Corner for you, young Brian!

 
Steve Adams05/05/2011 19:55:19
175 forum posts
Kinda reminds me of Terry Eatos Freebird,featured in RCM+E in the early 90s.Got some hints of John Rutters designs in There as well! Looking forward to this one,its nice to break the mold,once in a while,showing your wild side now Tim.A hearty Congratulations to you sir!
 
Tim Hooper09/05/2011 14:52:31
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Thanks guys!
 
I've unleashed the crayons upon an unsuspecting sheet paper and this is the result so far;
 
That big black bar is a 24" ruler to give a bit of scale to the proceedings.


AS the model looks a bit boy-racerish, I've opted for a 10% aerofoil to minimise drag a little, then printed them out via Profili. I'll draw in the spars manually later....
 
tim

Edited By Tim Hooper on 09/05/2011 14:53:17

Tom Wright 210/05/2011 00:59:14
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Tim .You have just demonstrated why i am so reluctant to submit designs and plans for publication ,i am not artistic and can only draw straight lines .
 
Even you prelim work is .........so good ! Do you have the weight and wing loading projections yet ? the motor selection suggests weight at around 4.5 LBS.
 
 
Grrr
 
Tom.

Edited By tom wright 2 on 10/05/2011 01:03:13

Tim Hooper10/05/2011 08:16:22
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2803 forum posts
2346 photos
Hi Tom!
 
Thanks for the compliments, mate. I'm not particularly artistic either - but I've been around long to develop a feel for the TLAR quotient of an airframe. TLAR stands for 'that looks about right'........
 
The wing area has come out to 364"², and power system I've earmarked is a favourite, known system - Turnigy 35/42 1250Kv, 9x6 prop and 3S 2700 li-po - that pulls a measured 450 watts.
 
This is the same system that I use in the 49" Seagull PC9, and my own 56" Airspeed Courier. Both of these models weigh well under 3lb, so I'm hoping the Clean Sweep will be in the same ballpark. So no shortage of power then.
 
tim
Tom Wright 210/05/2011 13:32:20
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3908 forum posts
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Tim Thanks.
I tend to follow your designs as generally the wing loadings are low making it practical for a wider range of pilots and terrains , if a model is pretty or even scale it does not have to be heavy and that's were the structural engineering comes in to the design equation, you might have gathered i don't like " pretty bricks" much, but i do appreciate your ability to combine good looks with low weight.
 
Tom.
Lindsay Todd10/05/2011 19:22:07
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Very nice Tim, bit Reno Racer ish, would make a good club 20 pylon at that size, mmh there's an idea?
Linds
 
Chris Bott - Moderator10/05/2011 21:35:25
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Mass build racers for next year ?

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