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Old Apr 13, 2013, 02:06 AM
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Australia, VIC, Warragul
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Sopwith Pup

Hi, some infomation if you would be so kind, I am currently building a 1\7 scale (I think) Sopwith Pup, It's a Dave Boddington Kit, with a wingspan of appro 40 inches (1 meter) and an approx AUW of 3-3.5 pounds, originaly this kit was designed for a 15 size glow motor, but I would like to convert it to electric, being a novice in this area, I would really like some advise re motor and battery combo, I woud prefer to swing a 10 to 11 inch wodden prop, and being a scale model, to fly in a scale like manner, ie quite slowly, most of the stuff I have looked at is at hobby king, but would gladly go to my local hobby shop if I knew what I was talking about, which I dont, revs per volt? you lost me! How many watts do I kneed to fly a 3-3.5 model? You lost me, so, any information you can point in my direction would be most appreciated,
regards
Telly
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Old Apr 13, 2013, 03:14 AM
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Norfolk, England
Joined Sep 2001
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If it's the Boddo design I think it is, it's 1/8 scale and heavy. I've built two of them, both for wet and smelly power, but have designed a 1/8 Pup of my own. Have a look at the build thread for that, it may give you some ideas.
Otherwise, just try to shed as much weight as possible so you end up with a finished model weighing under 2 lb. Quite a bit under, if you can manage it.

This thread covers most things.
http://www.rcgroups.com/forums/showthread.php?t=1109885


Pete
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Old Apr 13, 2013, 08:31 AM
What's 3D?
trumps's Avatar
Australia, WA, Ellenbrook
Joined Feb 2008
3,316 Posts
+1 for Pete's version, it is an absolute cracker of a plane, mine ended up weighing in at a portly 37oz but she still floats along in an extremely slow and convincing manner!

Good luck
Craig
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Old Apr 13, 2013, 10:44 AM
The Hun in the Sun
vonJaerschky's Avatar
Canada, BC, Comox
Joined Nov 2003
7,442 Posts
Another vote for a different design. You can convert it, but you won't be very happy with the final product. Aerodrome R/C also has a nice 40" laser cut Pup kit intended from the outset for electric power. You would be much happier with one of those two airplanes.
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Old Apr 13, 2013, 12:54 PM
I eat glue
Canada, NS, Yarmouth
Joined Jul 2006
3,482 Posts
Yup, I've got Pete's Pup as well, not finished yet but it's going to be lighter than the Boddo design.
I am getting his plans for the 1/5 scale, and will lighten it for electric.
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Old Apr 13, 2013, 02:11 PM
Slip the surly bonds...
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Christchurch,England
Joined Aug 2004
2,680 Posts
Boddo designed for people to crash his models and walk away with no repairs to do (I know, I built his Moth 20 and had lots of fun with it). I would not try the conversion route, but as everyone has said, go for a purpose-designed electric version.

Mike
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Old Apr 13, 2013, 03:19 PM
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Norfolk, England
Joined Sep 2001
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As Mike said, Boddo did great designs if you needed a durable model - I perfected (?) my flying with his Tinker biplane and loved his Red Knight Fokker style biplane. That they flew well was proven when the Red Knight got shot down by someone who'd forgotten what frequency he was on. It sort of half rolled to inverted and then just carried on flying (still inverted) until it strained itself though a barbed wire fence. It wasn't durable enough to survive that though.

Since you already have the DB model, it might be worth looking at other designs to see where you can shed weight. Quite obviously Pups of this size fly well at 2 1/2 lb and that should be doable with the kit, but it will mean replacing several parts with lighter or thinner material.

Pete
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Old Apr 13, 2013, 09:05 PM
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Australia, VIC, Warragul
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Well, thanks very much for the input, you've convinced me, as I've allready built and covered this plane(except for lower wing and tail feathers, I'm going back to the original plan and fit a small diesel motor( I have plenty!). If I cant get the weight down it will go like a rocket, and we dont want that do we. Unfortunatly scale kits like this are very hard to find here in Oz, and I'm no scratch builder, I dont have the patience, and most ARF stuff does'nt turn me on, they look....well the look like ARF's cheap and nasty, I would much prefer to build from a kit, and again, if it's going to be a larger, say 1\6 scale, then it must have a four stroke...
But I do love the Sopwith Pup. I had dreams in my mind eye, of a small electric Sopwith Pup, just gracefully floating past me with its little electric motor propeling it not much faster than walking pace, and then a sharp right turn see's it dramaticlly head for the sun in search for that hun!
Telly
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Old Apr 13, 2013, 09:14 PM
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Just had a look at the Aerodrome r\c site , so many planes, so little time!
Telly
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Old Apr 14, 2013, 12:14 AM
What's 3D?
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Australia, WA, Ellenbrook
Joined Feb 2008
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Quote:
Originally Posted by Telly View Post
Just had a look at the Aerodrome r\c site , so many planes, so little time!
Telly
Don't forget Manzano's, all of
pete's kits are available through Charlie, great kits and service. we are spoilt for choice!

Craig
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Old Apr 14, 2013, 04:27 AM
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O.K. so I weighed what I have so far, initially I covered the top wing and fus with white solortex, so what I have including the under carraige, weighs 1 pound, the wheels are really heavy IMO, maybe if I make wheels from balsa and foam, and cover the rest, ie lower wing and tail feathers in tisue\silk.......?
Telly
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Old May 06, 2013, 05:22 AM
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Australia, VIC, Warragul
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on reflection, and looking at this kit, I'm going tohave a go at electrifi it, if successful I'll let you know, if not only I will know
Telly
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Old May 06, 2013, 09:08 AM
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Norfolk, England
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Many years ago I did see a photo of one that had been electrocuted. IIRC, it was in the Gordon Whitehead book. That flew on a geared 600 brushed motor and around 10 Ni-Cads I believe.
Nobody said it can't be electrified, just that there are lighter options out there. You did specify that you wanted it to fly slowly.
If you're going brushless and LiPo, you may find you need the weight of those wheels to help with balance.

Pete
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