David B

Hi all,

I'm beginning a Sig King Kobra & will be installing Spring Air 202 HD retracts. This is my first foam core wing so I'm looking for advice from those with more experience regarding the retract installation. Sig recommends the construction of a plywood plate anchored to dowels which are inset into the foam wing. My concern is how durable this design is long term. Do the dowels loosen up in the foam after time or punch through the top of the wing under (reasonably) rough landings? I realize you can always destroy your gear if you land hard enough. I was considering constructing a "box" structure of 1/8" x 1" x 24" hardwood to tie the plywood plates together & transmit the landing loads to the fuselage. I know this would be much stronger with a minimal weight gain but am wondering if it's worth bothering with. Additionally, these pieces would also act as spars & make the fiberglass joiner unnecessary. I'm sure it's been done before, is it worth it? Thanks in advance!

David B

hrrcflyer

David,

Take a look at the King Kobra build thread started by ExpiramentalAvaitor here on RCU. His build thread is superbly done and shows how he made a plate for the retracts.

I have a King Kobra 60 to build as well. What engine are you planning to put in yours? I have a NIB Rossi 61 Fire for mine and it should haul it around rather nicely.

Good luck with your plane!!!

David B

Thanks for the reply, David. Yeah, I've been following that thread for quite a while, in fact it's what finally pushed me over the edge & got me to buy the KK. I know Mike is using the dowel anchoring method, I'm just curious if others have felt it necessary to go with something a little stronger.

dhal22

i too, have a king kobra done this way. the build is essentially done and waiting for paint so so far no experience with the plate and dowel method but it appears to be a plenty strong method of affixing retracts.

david

scale buff

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I've flown my KK for about five years. It has Spring Air retracts and the plates were installed following the instruction manual. There hasn't been any problems with the plates coming loose or punching through the foam. Once that wing is sheeted, it's very tough. I think if you follow Mike's thread, you can't go wrong. His documentation is so good Sig should hire him.

Frank T.

David B

Yeah, I'm following Mike's lead. I have one retract plate installed & will finish the second one soon. I'm taking some pics so I'll turn this into a build thread as well. However, my documentation & descriptions won't be as good as Mike's!

hrrcflyer

David B,

I can't wait to see some pics..... I'm also glad you are doing a build thread as well. It doesn't make any difference to someone like me if your thread is not as detailed as Mikes. Each person has their own way of doing things and I like to read these threads to see how other people do things.

I have a King Kobra kit as well and it will be my first foam core wing kit with retracts too. What engine are you going to put in yours? I am thinking of trying one of the Axe Rossi 61's in mine. If it has as much power as my older NIB Rossi Fire 61, it should really make that King Kobra howl...

Keep us posted with your progress. I, for one will be following along religously..

dhal22

the spring air 202 hd's are a hard to beat system. i will use them in all of my 60 size birds. i already own 4 sets.

david

David B

Hello all,

I'm finally  back to working on my King  Kobra.    I'm wrapping up the fuselage construction and am starting to think ahead about a pilot.   What  are you using  for a  jet bust pilot?   I know Century Jet makes a 1/10  scale but I haven't called to confirm it's dimensions to see if it'll fit.  Also, does anyone have a recommendation for a relatively simple instrument panel or other cockpit recommendations?   Thanks again for all the help.

David B