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Old Jul 15, 2010, 01:17 PM
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S/E Michigan
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Build Log
Vk Fokker DRI

I started a thread for this model expressing a desire to go electric with it as a discussion. The plane is framed out, and needs to loose weight, so I began this thread as a build log to chronicle the various means used to loose ounces.
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Old Jul 15, 2010, 03:20 PM
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Skycruiser's Avatar
Fairlie, New Zealand
Joined Nov 2006
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I'll be watching this one, I've got the VK Nieuport 17 waiting for a 'one day' build. There's a lot of hardwood in the kit that can be replaced with balsa, IMO.

Good luck with the build.

Nick
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Old Jul 15, 2010, 04:17 PM
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United States, OR, Fairview
Joined Jul 2006
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Just a thought, but as you'll need more weight ahead of the CG than behind, maybe you might consider keeping the firewall as is?

Also, depending on where the batts and ESC end up, you may need some cooling holes through the firewall, anyway.

James
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Last edited by Deuce; Jul 15, 2010 at 04:19 PM. Reason: Additional thoughts...
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Old Jul 15, 2010, 05:20 PM
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Plan on having to mount battery pack(s) right behind the firewall or protruding through it along side the motor and having receiver, speed control, rudder and elevator servos at or ahead of the indicated cg location to get 'er to balance without a lot of additional nose ballast. Avoiding any unnecessary weight aft of the cg point will help keep the model light overall which should pay off in scale-like performance. Keeping weight of covering to a reasonable minimum can save considerable weight on this size of a model. Good luck with this interesting conversion and build.
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Last edited by E-Challenged; Jul 15, 2010 at 05:26 PM.
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Old Jul 15, 2010, 06:53 PM
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USA, FL, Mt Dora
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I agree with James and E, if you can't shave some significant weight from the tail , you will need that heavy firewall and keep everything towards the nose. This means even moving the servos as far forward as possible.
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Old Jul 15, 2010, 09:11 PM
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Thanks for the input guys. It may be a option to mount the battery (or batteries, 2 in series?) on the front of the firewall. Stick them on with velcro. Black velcro, and give the batteries a light coat of flat back...
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Old Jul 15, 2010, 11:01 PM
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Quote:
Originally Posted by E-Challenged View Post
Plan on having to mount battery pack(s) right behind the firewall or protruding through it along side the motor and having receiver, speed control, rudder and elevator servos at or ahead of the indicated cg location to get 'er to balance without a lot of additional nose ballast. Avoiding any unnecessary weight aft of the cg point will help keep the model light overall which should pay off in scale-like performance. Keeping weight of covering to a reasonable minimum can save considerable weight on this size of a model. Good luck with this interesting conversion and build.
I've been thinking about covering.... I love Solartex, but I know it is relatively heavy. In the "One more Stuka build" thread, Sharkman used a thin clear covering which he then painted. Some new tecniques have come down the pike over the last 25 years. I am happy to listen to any suggestions.
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Old Jul 16, 2010, 09:46 AM
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Canada, ON, Kingston
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Many years ago, I built a VK DrI for gas but converted it to electric before covering. There were no structural (lightening), changes. For comparisons, I used an Astro 25 geared, (12oz.) and 14 X 1000SCRs - nicads - (20 oz.) mounted under the middle wing from the firewall aft, full width of the fuselage. Total weight was 5 3/4lb. ready to fly. Covering was laminating film painted with Floquil RailRoad Colours (laquers).

Martin
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Old Jul 16, 2010, 10:41 AM
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How was flying at 5 and 3 quarter pounds? What is laminating film, and how is it applied to the frame?
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Old Jul 16, 2010, 10:46 AM
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I would advise against Doculam for a model of this size. The weight of a good opaque paint job can almost equal the weight of a light iron-on covering. Doculam requires special care in masking and getting paint to stick plus it is somewhat easy to puncture.
I'd go for a relatively lightweight standard easy to get covering that has good opaqueness and is easy to patch when necessary.
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Old Jul 16, 2010, 12:19 PM
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Good advice E-Challenged, Solarfilm makes a product called Litespan. It has no adhesive, the adhesive must be brushed on the frame. I like the sound of it, has anyone here used it?
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Old Jul 16, 2010, 01:27 PM
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At 5 3/4lb. it was fine, that's only 10% more than their suggested gas weight. Take off and landings were typical DrI - lots of rudder finese - but in the air it had a comfortable margin of power at about 400W.

Actually, the laminating film stood up quite well. It is available in several thicknesses, but I used the ends of the rolls we use at school so I don't know how thick mine was. Certainly, once you start tearing it, it continues pretty easily. It is a two layer film with the cloudy polyethalene side being the adhesive side - no other adhesive needed. There is a 40 page thread on using it on this forum:

http://www.rcgroups.com/forums/showt...aminating+film

IMHO Litespan is too light and fragile for this size of plane. I'd recommend Polyspan and dope, but that is usually more work than film.

Martin
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Old Jul 18, 2010, 11:12 AM
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I cannot work with dope anymore, one sniff nauseates me. I may use doculam, at least on the tail feathers.
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Old Jul 18, 2010, 01:16 PM
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You can't take much weight out of stab and contriol surfaces. Rear fuselage longeron and stringer structure and tail skid setup may offer some possibilites. Avoiding a little weight in the long rear end avoids need for much more weight in the short nose to cure tail heaviness. Tail-heaviness is BAD, a little nose-heaviness is GOOD at least for the first few flights.
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Old Jul 18, 2010, 01:45 PM
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Yup, a few licks with a fine grit paper and the rudder will be ready to cover.
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