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anyone building a king kobra?

Old 08-07-2007, 06:42 PM
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Default RE: anyone building a king kobra?

found my camera, i will post a few progress photos. the 1st will be a simple side view of the fuse. i can't load very many photos i guess.
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Old 08-07-2007, 06:46 PM
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Default RE: anyone building a king kobra?

the next photo shows an idea i had for an internal rudder, i will try to load 2 photos this time. the 2nd photo shows the control arm protruding through the stabilizer. i suppose most classic pattern planes wouldn't have this much room in the aft section.
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Old 08-07-2007, 06:49 PM
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Default RE: anyone building a king kobra?

the next photo shows the future rudder next to the control arm for reference. The wings were sheeted today with polyurethane glue. i will post photos of that tomorrow after the poly dries.
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Old 08-07-2007, 07:02 PM
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Default RE: anyone building a king kobra?

The kit is an easy one to build, i am just adding more things than the kit planned for, so it is taking longer to build.
Old 12-25-2007, 06:41 PM
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Default RE: anyone building a king kobra?

with all the hanging out i do on this site, i don't the time to update my king kobra build thread. taking a week off for christmas gives me a little down time so i will get some more photos up for your viewing pleasure and comments.
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Old 12-25-2007, 06:42 PM
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Default RE: anyone building a king kobra?

i guess the photos might be posted in less than perfect completion order.
Old 12-25-2007, 06:56 PM
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Default RE: anyone building a king kobra?

just when i though i had some down time i have to go. i will post more later

david
Old 12-25-2007, 08:35 PM
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Default RE: anyone building a king kobra?

i will post some wing photos next. the retracts are spring air.
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Old 12-25-2007, 08:41 PM
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Default RE: anyone building a king kobra?

due to lack of progress photos, i am skipping to some more recent ones. all major construction is done and glassing will start shortly.

david
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Old 12-25-2007, 08:46 PM
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Default RE: anyone building a king kobra?

the engine will be a piped Mark/Moki .61 capable of rpms in the 17,000 range. it should scoot once finished. will post more photos soon, now that glassing has started.

david
Old 12-30-2007, 03:57 PM
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Default RE: anyone building a king kobra?

what a breeze glassing with .75 oz cloth and Minwax polycrilic. I've glassed the fuse and painted 4 coats of polycrilic (sanded and tack clothed after the 2nd coat) in 2 afternoons. 2-4 more coats and i'm ready for primer. since the glass doesn't show up well in a photo, i will post photos after the primer has been put on.
Old 12-30-2007, 05:39 PM
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Default RE: anyone building a king kobra?

Great to see the retracts and especially the nose gear!
Old 12-30-2007, 05:57 PM
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Default RE: anyone building a king kobra?

I don't mean to belabor the point, but I have never seen a foam core cut up the way you did and it looks to me like it will loose a lot a strength doing that. How do these wings hold up with everything cut out like that. Like I said, I have never seen one cut up like that and am very interested in how they hold up. I have seen them cored out like balsa wing ribs, but never like this. Thanks for the help.
Ed
Old 12-30-2007, 06:34 PM
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Default RE: anyone building a king kobra?

all that i cut out was the retract and servo holes. there are threads here on RCU where the foam is completely honeycombed out. scarcely enough foam left to glue wood to. my wing is very strong as is is right now.
Old 12-30-2007, 06:45 PM
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another thought is i used polyurethane glue to attach the balsa skins to the foam cores. incredibly strong results. i used a foam roller and rolled the glue from a paper plate and applied it on the foam cores. you can literally push/roll the glue around until you have a shiny, very thin sheen on the cores. then i lightly misted the balsa with water, applied the skins and weighted heavily for 24 hours. a rock solid result was achieved. i am very happy with the results.

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Old 12-30-2007, 06:47 PM
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Default RE: anyone building a king kobra?

The one I was talking about was post #5. The wing has so many cutouts that I just don't see how it will stay together. I have been out of the hobby for a few years and we used to do a little coring of the foam cores, but nothing like that. That is why I was wondering if it will hold together. I know things were going to change a little, but boy are they different. I just noticed that the wing I was talking about was not yours. Guess I need to read a little closer, or pay more attention.
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Old 12-30-2007, 07:47 PM
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Default RE: anyone building a king kobra?

see there it is. it's on my own thread and i had forgotten. that is someone else's wing, not mine. i've heard that it is still plenty strong, but too much work for me. besides the KK is a little heavy anyway and still flys well
Old 12-30-2007, 09:34 PM
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Default RE: anyone building a king kobra?

also, thanks for stopping by and visiting my thread 8178. I admire your work. as for the retracts, i wonder if Spring Air offers volume discounts. i have several projects in mind, all with retracts and i love spring air's retracts.
Old 12-31-2007, 08:23 AM
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Default RE: anyone building a king kobra?


ORIGINAL: mred33

The one I was talking about was post #5. The wing has so many cutouts that I just don't see how it will stay together. I have been out of the hobby for a few years and we used to do a little coring of the foam cores, but nothing like that. That is why I was wondering if it will hold together. I know things were going to change a little, but boy are they different. I just noticed that the wing I was talking about was not yours. Guess I need to read a little closer, or pay more attention.
Ed
The strength of a wing comes from the sheeting, the foam only holds the shape of the sheeting. Extreme coring like that hardly affects the strength at all. If you fully sheeted a wood wing, it wouldn't need spars at all, etiher.
Old 12-31-2007, 10:21 AM
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Default RE: anyone building a king kobra?

Hi Dave,
Ran across this foto of my King Kobra (w/ HB .61 PDP) from '97 so thought I'd take a digital pic and then see if I could post it. It was given to me in rough shape and I felt it needed "restored" before I could fly it. And since it was heavy, one thing led to another- all the covering came off, took a carving knife and 80 grit block the fuse corners and leading/trailing edges. It had mechanical retracts and since it was still too heavy, I moved the mains forward and pulled out the nose gear before re-monokoting the whole thing. Would have been a lot easier to have just started with a fresh kit. Yea- maybe sacreligeous as a tail-dragger, but it looked the same in the air! Have fun with yours!
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Old 12-31-2007, 11:16 AM
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Default RE: anyone building a king kobra?

Let's not forget that the original ME-262 was a tail dragger also.

I would have to disassemble the empennage, slide the horizontal stab forward and then extend the rudder down to the bottom of the fuselage. The airplane simply will not handle correctly set up as stock. Adverse yaw might be tuned out by mixing ailerons, but all of that drag of controls fighting each other just to fly straight will put a serious penalty on the available power.

Then again, this model, and the Kougar, were never designed to be true pattern planes anyway. Just a quirk of mine. With all of that said, they are very appealing sport models and they look good too.


Ed Cregger
Old 12-31-2007, 11:44 AM
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Default RE: anyone building a king kobra?

Good point about the Me262, I'd forgotten that. Yeah, I remember the KK roll coupling. It flew far different than the Bridi XLT I was flying at the time, but it was good sport plane and I enjoyed it for that.
Old 12-31-2007, 05:44 PM
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Default RE: anyone building a king kobra?

i chose this plane for building practice mostly. retracts, flaps, another glassing project were things i wanted experience with. my interest in classic pattern planes came along afterwards. mostly by looking at everyone's projects here. although not a true pattern plane, the KK is still supposed to be fun to fly. and it looks great on tricycle retracts! i have ordered a blue angel plans, cores and canopy kit and a bridi xlt kit to really get into pattern planes.
Old 12-31-2007, 06:05 PM
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Default RE: anyone building a king kobra?


ORIGINAL: dhal22

i chose this plane for building practice mostly. retracts, flaps, another glassing project were things i wanted experience with. my interest in classic pattern planes came along afterwards. mostly by looking at everyone's projects here. although not a true pattern plane, the KK is still supposed to be fun to fly. and it looks great on tricycle retracts! i have ordered a blue angel plans, cores and canopy kit and a bridi xlt kit to really get into pattern planes.
I’ve always liked the lines of the Kobra especially with tri-gear retracts. Sig sold bunches and bunches of them. It is a lot of fun to fly and I appreciate you taking the time to share the build with us.
Old 12-31-2007, 06:24 PM
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my build thread isn't quite the equal of others here but like my building skills my threads will improve with practice.

david

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