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SIG Kougar Refurb and Electric Conversion

Refurbing my old Sig Kougar after many years of hard flying

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Gary Clark 109/11/2019 15:08:26
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242 forum posts
131 photos

Sorry guys, its been a busy few weeks and, any time I've had, it's been bloody cold in the garage!

I've purchased a heater and tidied the workbench to get back into things. Retracts are on they're way and some peel ply for glassing the tail to save it getting bashed whilst the rest catches up!

I must admit though, referring old aircraft is loads of fun and feels like a new plane but with loads of building already done so its quick! Anyone got any interesting projects on the go just now?

Gary

Gary Clark 114/11/2019 16:07:56
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242 forum posts
131 photos

Hi guys,

Finally got some more work done on the kougar. The horizontal stab and fin are both done and just require hinges. Made a start on trying to dig out the old undercarriage block from the wing ro get ready to fit retracts. The words I would NOT use to describe how thos went would be words like "well", "smoothly", "cleanly" or "without frustration" as seen below..

20191114_151709.jpg

The res lines show where the foam got damaged below and needs replacing. This is far from ideal but with the strength of gorilla glue and new skin, I'm sure she'll be strong enough when repaired as I've seen it completely hold together crashed foamies!!

My efforts to clean it up gave me this

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I'll get some new foam cut to fill the damage and get it re-signed before sorting the retracts. The wing will need quite a bit of tidying up but that's the whole point in this project.

Gary

Gary Clark 110/12/2019 18:36:52
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242 forum posts
131 photos

Hi all,

I've got some more done to the wing and replace the foam but still need to skin it. I've tried to make my own foam cutter with a brushed esc and servo tester but not had a lot of luck so far.

I moved onto the fuselage to see how much work is going to need done there........turns out loads! I feel like i'm going to be rebuilding this entire plane rather than refurb!

20191201_132149.jpg

As you can see, getting the fuel tank out meant ripping off the whole bottom of the front end and the firewall was pretty damaged with fuel over the years so that's been cut out now and a replacement made. Next step is fitting the nose retract to see what space i have for a battery and finding out where my battery hatch will be. Lots of figuring out to do.

The tail is about to get hinged then glassed so at least that bit is almost complete!

Gary

john davidson 110/12/2019 20:02:15
65 forum posts

In order to get the battery further forward it might be best to cut out the old firewall and situate a new one at the proposed motor mount position,extending the fuse and making a battery hatch at the same time.I have converted several of my old glow models and it usually impossible to get a satisfactory cg otherwise .

Ron Gray10/12/2019 21:58:48
2235 forum posts
978 photos

For cutting foam out I use a cheap pistol type soldering iron with a U shaped wire 'bit', cuts lumps of foam out quickly and cleanly.

Gary Clark 111/12/2019 19:10:09
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242 forum posts
131 photos

Thanks John and Ron, both very helpful tips there.

I hadnt had too much thought toward CG yet since it feels like there is so much else to but I'll have a look later and see how she is looking.

I did find that the CG had to be a bit further back than suggested on this to help open up the full flight envelope but didnt bother to note down what worked.......well done me.

Despite feeling like EVERYTHING needs fixed, I'm enjoying this restoration job. It's like building a new plane but with lots of the work already done!

Gary

Gary Clark 120/12/2019 21:11:23
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242 forum posts
131 photos

I've managed to get a bit more done, mainly with power selection and setting up the new firewall position. Lot's of measuring and temporarily placing things to check fit nut nothing worth taking photos of to share.

I did have my first go of using peel ply whist fibreglassing. I have glassed a fair bit an am fairly confident with it but fancied a go of peel ply and the hope of less sanding. As far as the peel ply was concerned, it was a total success and when removed, i gave the rudder a very light sand with 200 grit for a minute or so then a coat of primer to see how it came out...

20191220_144111.jpg

Clearly not perfect yet but considering that it did not require a flow coat or lots of sanding, i was very happy. There a some pin holes and you can see the weave in a couple of small places but those are easy touch ups.

Now the problem. I glassed one side of the rudder, fin and horizontal stab and left to dry overnight. i was excited to peel the peel ply off the next day considering how well the rudder had turned out but i was pretty shocked at what i found. All the part were pretty badly warped and the fin and horizontal stab are total write offs

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Those were lovely straight pieces when i started!!!! I'm not sure what has happened but i made those part from two sheets layered as i didn't have any 3/16 available so maybe having two sheets that were different have allowed this to happen as the epoxy cure? i have no idea but what i do know is that i'll be making new ones sad

I have a wood order going into SLEC to reload my stores so needless to say, i have added some hard sheets of 3/16 to that order! The joys of building!

Gary

kc21/12/2019 16:13:07
6578 forum posts
173 photos

Were the two layers of balsa laminated with grain parallel or at right angles?

For this job I would have been tempted to laminate with one layer at 45 degrees ( parallel to the top edge of the fin ) rather than 90deg. Normally using 1/4 instead of 3/16 would suffice though.

Peel ply was a new term to me but a Google search answered my questions. Interesting though.

Gary Clark 121/12/2019 21:26:49
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242 forum posts
131 photos

I honestly cant remember what the grain direction was KC (which shows I wasnt thinking about it) but one way or another I messed it up as I've never seen that before. I'm thinking it could have been the same direction and different quality of wood as they all came from the same laminate. Good little lesson though.

I fancied trying peel ply since the results look great. Loads of videos on youtube and Danny Fenton ones are particularly useful. My limited advide would be use more epoxy than youd think and the results are great

Gary

Gary Clark 113/01/2020 22:13:28
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242 forum posts
131 photos

Post christmas carnage is complete and I e managed to get some work done on the kougar.

First job was to remake the tail parts thinking

20200113_211250.jpg

Still got the leading edges to shape and re-hinge and bloody hope they stay flat when glassing this time!

The majority of the wing is back to a starting point and ready to fit retracts and ailerons

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Replacement leading edge is on now and ready to be drilled for the mounting dowels.

Got bits and Bob's done on the fuse but nothing worth showing yet. If I'm being honest, if these were easier to get hold of now then I'd just have bought a new one as this is more work than I thought initially crook

Gary

Ron Gray13/01/2020 22:38:14
2235 forum posts
978 photos

Ah but just think of all the fun you’re having Gary wink

Gary Clark 113/01/2020 22:47:40
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242 forum posts
131 photos

Haha I'd be having more fun if I only had to do things once Ron! It will be worth it when the old lass is back in the air

Gary Clark 130/01/2020 15:16:02
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242 forum posts
131 photos

More progress has been made on the kougar.

The wing has 1 retract in and has been tidied up overall. Tail has been remade but I'm not totally happy with the glassing again so might have to start attempt 3 angry

Cowl and nose gear are in as seen below

20200130_143516.jpg

More work needed to reinforce and tidy up but getting there with it.

I have emailed 4max about a motor as the one i was planning on using needed a 13" prop and i don't have the clearance. i really id like to stay with 4s battery for weight and also i have a few of those around already.

Gary

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