Enlarging plans
05-07-2012, 05:46 AM
#1
Enlarging plans
I know it's been asked before but the answers have not been clear. Can you enlarge plans and have it fly properly and structurally will it be sound? I have back ground on building but not from scratch. I already have a set of plans for a 31" WS control line plane. It is very simple to build that's why I like these plans. It's a Mr Mulligan, like a J-3 cub most of it is square sticks except for the round bottom on this.. I am going to enlarge it 2.5 times and make it 77.5" WS and use a DLE30. I have CG calculatoins and will reinforce the firewall and wing center, etc. the real question is should I keep the wood thicknesses enlarged? The new stringers for example will be 1/4" as well as the bulkheads. Should I go smaller stringers and double them( same difference I think)? The firewall will be at 1/2". Keep in mind most of it is sheeted. I am going to use thinner sheetng, 1/4" would be to heavy and harder to use. I am going to split the wing and use a wing tube for easy transport, using plywood at the root and on each rib carrying the tube. Do I need to add more ribs/bulkheads since the spacing is further apart? Other than the small details any suggestions or things to consider?
05-07-2012, 06:17 AM
#2
RE: Enlarging plans
ORIGINAL: xcz5785
I know it's been asked before but the answers have not been clear. Can you enlarge plans and have it fly properly and structurally will it be sound? I have back ground on building but not from scratch. I already have a set of plans for a 31'' WS control line plane. It is very simple to build that's why I like these plans. It's a Mr Mulligan, like a J-3 cub most of it is square sticks except for the round bottom on this.. I am going to enlarge it 2.5 times and make it 77.5'' WS and use a DLE30. I have CG calculatoins and will reinforce the firewall and wing center, etc. the real question is should I keep the wood thicknesses enlarged? The new stringers for example will be 1/4'' as well as the bulkheads. Should I go smaller stringers and double them( same difference I think)? The firewall will be at 1/2''. Keep in mind most of it is sheeted. Ibam going to use thinner sheetng, 1/4'' would be to heavy and harder to use. I am going to split the wing and use a wing tube for easy transport, using plywood at the root and on each rib carrying the tube. Other than the small details any suggestions or things to consider?
I know it's been asked before but the answers have not been clear. Can you enlarge plans and have it fly properly and structurally will it be sound? I have back ground on building but not from scratch. I already have a set of plans for a 31'' WS control line plane. It is very simple to build that's why I like these plans. It's a Mr Mulligan, like a J-3 cub most of it is square sticks except for the round bottom on this.. I am going to enlarge it 2.5 times and make it 77.5'' WS and use a DLE30. I have CG calculatoins and will reinforce the firewall and wing center, etc. the real question is should I keep the wood thicknesses enlarged? The new stringers for example will be 1/4'' as well as the bulkheads. Should I go smaller stringers and double them( same difference I think)? The firewall will be at 1/2''. Keep in mind most of it is sheeted. Ibam going to use thinner sheetng, 1/4'' would be to heavy and harder to use. I am going to split the wing and use a wing tube for easy transport, using plywood at the root and on each rib carrying the tube. Other than the small details any suggestions or things to consider?
limeybob
05-07-2012, 09:28 AM
#4
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RE: Enlarging plans
The safe and easy way is to look at a similar size and type of model and use similar construction methods and material sizes. It's much easier to restyle an existing design of the right size and just make it look like your desired shape. Probably fly better too.
But in this instance it's a huge change of size and probably not have ailerons & rudder if it's control line so better avoided. You will spend so much time and money building a large model it's better to do it properly. When you can download a free plan for a Howard Pete ( OK its low wing! ) at the right size why not build that? In any case study the construction methods and see if its applicable to a Mulligan. Look at the David P Andersen page [link]http://www.mnbigbirds.com/Andersen%20Plans.htm[/link] for this free download from a top designer.
But in this instance it's a huge change of size and probably not have ailerons & rudder if it's control line so better avoided. You will spend so much time and money building a large model it's better to do it properly. When you can download a free plan for a Howard Pete ( OK its low wing! ) at the right size why not build that? In any case study the construction methods and see if its applicable to a Mulligan. Look at the David P Andersen page [link]http://www.mnbigbirds.com/Andersen%20Plans.htm[/link] for this free download from a top designer.
