Tony j Posted May 4, 2018 Share Posted May 4, 2018 hi all looking for confirmation on the direction of the grain when making the balsa bulkheads /formers in the fuselage is it vertical as in bottom of plane to top many thanks in advance Tony j Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 4, 2018 Share Posted May 4, 2018 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Tony j Posted May 4, 2018 Author Share Posted May 4, 2018 Hi supertigrefan Yes balsa Kind regards Tony Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted May 4, 2018 Share Posted May 4, 2018 If the fuselage is taller than it is wide then 'top to bottom' grain is logical but it also depends on what else the bulkhead is intended to do. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted May 4, 2018 Share Posted May 4, 2018 If it is a single sheet of balsa, grain goes top to bottom. The structure will have the top and bottom of the fuselage with cross struts, or sheeting with the grain going from side to side to take compression loads. Quote Link to comment Share on other sites More sharing options...
Steven S Posted May 4, 2018 Share Posted May 4, 2018 This is confusing, The free plans in RCM&E like Peter's Grumpy Tiger Cub, Ballerena, Oddility, Werewolf, etc all show the grain as crosswise including the bottom sheeting and this is how I am building my Tiger Cub. Quote Link to comment Share on other sites More sharing options...
Dave from the future Posted May 4, 2018 Share Posted May 4, 2018 I would say grain side-to-side as in the plan above, then the formers are better able to support the compression forces when the sides are pulled in at the tail (or nose). Quote Link to comment Share on other sites More sharing options...
Ronaldo Posted May 4, 2018 Share Posted May 4, 2018 Agreed it is confusing, I've edited twice now lol ! Depends on the build, I would say on balsa sheeted sides, then formers having the grain across the shortest length is strongest. Edited By Ronaldo on 04/05/2018 23:54:55 Edited By Ronaldo on 05/05/2018 00:01:39 Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted May 5, 2018 Share Posted May 5, 2018 You might want the grain vertical in some circumstances eg where the rear fuselage has a tall stringered upper turtledeck section. In this case the former needs a couple of horizontal battens to resist the compression loads, maybe 1/8*1/4" on a smaller model, 1/8*1/2" on larger sizes. These would be positioned at the top and bottom of the sheet fuselage side locations. Quote Link to comment Share on other sites More sharing options...
brokenenglish Posted May 5, 2018 Share Posted May 5, 2018 If in doubt, laminate!!! Quote Link to comment Share on other sites More sharing options...
Tony j Posted May 5, 2018 Author Share Posted May 5, 2018 Hi thanks all yes had thought about laminating also thought about alternate former , grain one way then the next one the other but think I will look at grain up and some reinforcing as Bob suggest. A confusing subject for me at least . so many thanks to you all for your input I do like this site people are so helpful . Many years ago I asked a question on a unrelated hobby and was told I should know that !! Kind regards Tony j Quote Link to comment Share on other sites More sharing options...
Martin Dance 1 Posted May 5, 2018 Share Posted May 5, 2018 When I built Peter's Ballerina I decided to have the grain on the formers running vertically.My reasoning being that when cutting notches for stringers the bits either side of a notch were less likely to break off if the grain is vertical rather than horizontal. I suspect the ability of the former to resist compression loads in this orientation may well be improved by simply using a harder grade of balsa. Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted May 5, 2018 Share Posted May 5, 2018 The grain should run vertically. I don't put the grain on my drawing because I assume that common sense would prevail. Obviously it doesn't. I do sometimes but 1/4 X1/8" strips across the former if I feel that the may be some compression force on the sides of the former. Quote Link to comment Share on other sites More sharing options...
Tony j Posted May 5, 2018 Author Share Posted May 5, 2018 Hi Ah Peter a very timely intervention as it is your plan that I shall be working from in fact two of them 1. Bootlace 2.Oodalally Kind regards Tony j Quote Link to comment Share on other sites More sharing options...
eflightray Posted May 5, 2018 Share Posted May 5, 2018 You can often make a former from strips instead of cutting from sheet, this way you can have the grain in both directions. Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted May 5, 2018 Share Posted May 5, 2018 Ray that is a good system too. I really should use it myself but never think of it in time Quote Link to comment Share on other sites More sharing options...
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