Scruffmeister Posted November 1, 2019 Share Posted November 1, 2019 Hopefully a nice easy question, I know ribs should be cut from 'C' grain stock but what density is recommended? SLEC and Balsa Cabin both offer soft/medium/hard. If it is helpful, these ribs will be for a Mike Delacole Chilli Wind with an own design built up wing (the original was a foam core I believe) using 3/32" ribs. Thanks Quote Link to comment Share on other sites More sharing options...
Don Fry Posted November 1, 2019 Share Posted November 1, 2019 Ribs are not a stressed component, so soft would be OK. But most folk would use medium. If it was me I would use 3 mm depron foam. Cheaper, lighter, easier to cut, just as good for the job. Quote Link to comment Share on other sites More sharing options...
Nigel R Posted November 1, 2019 Share Posted November 1, 2019 So little weight in the ribs compared to the skin or spar components is not worth worrying too much. But as Don says they are not stressed. Personally I would use medium. Doublers around the uc will take care of the hard points. Quote Link to comment Share on other sites More sharing options...
alex nicol Posted November 1, 2019 Share Posted November 1, 2019 I've recently completed a Chilli Wind. I did the same and used a built up wing, Either Soft or Medium 3/32 will be fine (I used medium). I also fitted a set of electric retracts and shoved an Irvine 53 up front. Its a brilliant plane, hats off to Mike D for creating it Quote Link to comment Share on other sites More sharing options...
Scruffmeister Posted November 1, 2019 Author Share Posted November 1, 2019 Thanks all. Alex, do you have any build photos or even a wing plan you'd be willing to share? Quote Link to comment Share on other sites More sharing options...
alex nicol Posted November 1, 2019 Share Posted November 1, 2019 Hiya, Unfortunately no pics, I made it up as I went along. I used a full depth main spar from hard 1/4" slotted to half its depth and the ribs were also slotted to half depth and the spar was then capped top and bottom with 1/8" x 3/8" strip to form a girder type section. The ribs supporting the u/c plates were made out of 2mm lite ply. I never used any t/e stock but cut the ailerons from the wing and faced the openings with soft 1/4" . The wing was joined with an epoxied in feathered 1/4" birch ply brace and a 2" bandage was pva'd over the join. Hope this helps Alex Quote Link to comment Share on other sites More sharing options...
alex nicol Posted November 1, 2019 Share Posted November 1, 2019 Forgot to add, I also opted for a built up sectioned tail Cheers Alex Quote Link to comment Share on other sites More sharing options...
i12fly Posted November 1, 2019 Share Posted November 1, 2019 Never bothered with C grain myself (up to 60" span) and used medium to soft balsa. with unpleasant arrivals I've had spars crack but not ribs.... Quote Link to comment Share on other sites More sharing options...
Scruffmeister Posted November 2, 2019 Author Share Posted November 2, 2019 Thanks All! Quote Link to comment Share on other sites More sharing options...
Nigel R Posted November 4, 2019 Share Posted November 4, 2019 My Chilli had 3/32 ribs, hard 1/4 sq spars top and bottom, and is fully sheeted with 1/16. Spar webbing is standard stuff, 3/32, grain vertical. LE & TE were done with two strips of 3/16 each. The first one on (false LE) has the sheeting stuck to it, the next one on (the real LE, as it were) does not. It has solid stock ailerons as per plan. Joining was done with just a PVA soaked bandage. "Its a brilliant plane, hats off to Mike D for creating it" Indeed it is. Quote Link to comment Share on other sites More sharing options...
Scruffmeister Posted November 4, 2019 Author Share Posted November 4, 2019 Nigel, did you keep the dihedral as per the plan? Just intrigued if you just joined the wings "flat" or used only bandage without ply dihedral braces... Quote Link to comment Share on other sites More sharing options...
Nigel R Posted November 4, 2019 Share Posted November 4, 2019 Scruff, dihedral is exactly as per plan (I believe). No brace - just the bandage. My dad's usual method. Lots of airtime (I have about 7 or 8 hours on it so far), no problems, it is not babied around, it gets a good amount of flicks and spins and so on. My take, the usual thick glass cloth plus epoxy resin method is overkill for something this size / weight. I always use PVA & two (20 size) or three (up to 60 size) layers of the thinnest glass surface cloth/tissue. Again, never had a problem. A few coats of PVA gets quite a smooth surface and PVA also works quite well with iron on film. Quote Link to comment Share on other sites More sharing options...
Scruffmeister Posted November 4, 2019 Author Share Posted November 4, 2019 Thanks Nigel, good info. Might give that a try as it simplifies the wing design! Quote Link to comment Share on other sites More sharing options...
Nigel R Posted November 4, 2019 Share Posted November 4, 2019 No worries. Many ways to skin a cat. I would consider doing Alex's mod if I was building one again - sheet right back to the TE and cut out the ailerons afterward. This would also allow space for flaps to be added at the same time if the ailerons were made shorter and wider. The Chilli is quite slippery and I use up all of our runway unless there is a little breeze. I could use some brakes of some sort! If landing space is not at a premium that may not matter. Quote Link to comment Share on other sites More sharing options...
Scruffmeister Posted November 4, 2019 Author Share Posted November 4, 2019 Flaps is a nice idea, I definitely plan to cut the ailerons out as it's easy enough to do with the full skin I am planning... can always make a couple of different wings for it! Quote Link to comment Share on other sites More sharing options...
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