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Old Mar 11, 2010, 03:54 AM
smithy
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Cornwall, UK
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SU25K Frogfoot

Here is the start of my build log for my Frogfoot. Parts arrived back from Ian at SLEC UK , first impressions, wow! What a lot of parts! 4 sheets of ply and 3 sheets of balsa. I knew there were a lot of parts but when you see it all in the flesh instead of a computer screen its totally different.

Wingspan 65 inch
Lenght 63 inch
Twin 70mm power
Wing Area 485 sq inch
Ply and Balsa Construction
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Last edited by jumpy; Mar 12, 2010 at 02:58 AM.
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Old Mar 11, 2010, 04:10 AM
smithy
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Cornwall, UK
Joined Dec 2004
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Starting off with the nose section, attached formers F3 to F5 to the nose section floor. Then attached F2 and the cockpit formers. You will note that position of F4 has been moved forward from the first shot. First mistake on my part spotted, had it in wrong position on drawings.
Then added F1 and top and bottom nose keels.
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Old Mar 11, 2010, 04:20 AM
smithy
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Cornwall, UK
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Next added sub formers F3a, F4a and F5a together with F6 which combines intake rings. F5a and F6 have lower section cutout for nose landing gear.
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Old Mar 11, 2010, 04:32 AM
smithy
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Cornwall, UK
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Next added F7 and F8 together with top keel and 2 main bottom keels. This takes the build upto were the removeable wing section will start. On reflection i think i could have put more litening holes in the formers, they are 3mm birch ply and seem very rigid, just a bit worried about weight.
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Old Mar 11, 2010, 06:05 AM
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looks good so far. amazing how quickly it can go together when it's laser cut.
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Old Mar 11, 2010, 06:15 AM
smithy
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Cornwall, UK
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Your not wrong there Rich, spent about 3 hours so far on the build, I only stopped when i realised the time and shouts of ' how long are you going to be up there? ' from 'her indoors'!
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Old Mar 11, 2010, 08:29 AM
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Molde, Norway
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Nice to see something unusual, the Frogfoot is perhaps not the prettiest of planes, but like the A-10 it's built for a specific task and does the job well, will be watching this with interest. How big a plane will this end up being?
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Old Mar 11, 2010, 12:39 PM
smithy
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Cornwall, UK
Joined Dec 2004
524 Posts
Its going to have a wing span of 65 inch and 63 inch long, twin 70mm fan power and auw of about 85 oz, hopefully!!
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Old Mar 11, 2010, 05:41 PM
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Molde, Norway
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Cool! That's a fairly large plane for twin 70mm use but with the motors and batteries available today it should not be any problem getting enough power out of the fans. But are you sure about that AUW, if my math is correct that's not even 2.5kg and it sounds very low to me? I'd expect this to be a lot heavier than that, unless you know some secret tricks I don't. Those two power units (fan/motor/esc) will after all weigh at least 2.5 lbs including batteries so that's almost half your auw already. And it's not like there's a tiny little wing on it either so I don't think it would be that critical to keep the weight down on this one.
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Old Mar 11, 2010, 08:47 PM
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Joined Apr 2002
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I have to say - this is pretty cool. Nice to see a really different design, and the frogfoot isn't all that ugly either.

Any plans to have kits or short kits available to us? I'd be interested.
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Old Mar 12, 2010, 03:13 AM
smithy
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Cornwall, UK
Joined Dec 2004
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Your right about the weight, i think i was being a bit optimistic. I was kind of hoping to keep it under 100 oz, anyway we shall see. Kits could be a possibility, this is just a prototype to see how things work out. I was planning on making another after this if it went ok, but this time an SU39 instead. More stubby looking version of SU25 with larger cockpit and fin surfaces. Which do you think looks better?
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Old Mar 12, 2010, 03:31 AM
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both...............equally. how's that for decisive? LOL.
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Old Mar 12, 2010, 03:55 AM
smithy
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Cornwall, UK
Joined Dec 2004
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LOL, thanks Rich!!!. Theres not much difference regarding redesigning for the SU39, just the cockpit area flying surfaces and tail area, so i can just modify my original drawings of the SU25. I have also been making notes during the build of things to improve on the design. It always looks good on paper but when it comes to seeing it in the flesh you find things that don't seem quite right.

Phil
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Old Mar 12, 2010, 04:40 AM
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Phil, I think you've got a beaut there already. why mess with success? you gotta put that frog on the fin.............that's sooooooo cool. LOL. BTW, put me down for one if ya kit it, short kit it, or whatever.

Rich
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Old Mar 12, 2010, 04:42 AM
smithy
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Cornwall, UK
Joined Dec 2004
524 Posts
Got a bit more done last night, in between doing the bathroom. Added F9, stringers and intake bottom brace.
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