T E A M
PART 2: Building materials - Timber
Balsa : Needless to say, this is where everything got started. Commercially, balsa sheets are the primary material for flying model planes. They usually come in 3" wide by 36" long sheets. Commonly used thickness are 1/16, 3/32", 1/8", 3/16" and 1/4" sheets. 3/8", 1/2" and the thicker ones are used mainly for bulky parts usually carved to final shapes. Balsa is very prone to warp due to climatic changes. Choose your balsa carefully. If the material is meant for wing spars, LE and TE which alignment is very important, choose the straightest one you can find.
Balsa blocks are also available for solid components like nose cones and wing tips. However, you don't always need to use them. You can always explore the alternatives like laminating thinner sheets of balsa to get the correct thickness, rather than stocking up piles of balsa of different sizes. Also, balsa blocks often needs to be saw as penknife would be impractical to cut them properly. Making up parts from laminations saves you money and trouble to getting a bench saw.
Besides sheets and blocks, balsa sticks are also very useful for wing spars, leading and trailing edges, fuselage stringers and longerons. Available cross sectional shapes includes round, square, rectangular, triangular and wing leading and trailing edge profiles.
Not all balsa sheets and blocks are create equal. They come in different grade and weight and you should use them wisely according to thier properties. We generally grade them as soft, medium and hard. Soft balsa should be used for bulky parts or sheetings which strength is not the main concern. Wing sheetings, nose cone blocks and wingtip fairings should use soft balsa. Medium grade balsa are use generally on most parts of the airframe structural members which creates the shape like fuselage formers, side panels and wing ribs. Hard balsa is use for structural members which carry most of the airframe loads like wing spars and fuselage longerons. Some designs uses hard wood instead of balsa for such purpose.
Spruce : Spruce are dense hardwood, but soft enough to be shaped with a penknife and a junior hacksaw blade. They come in sticks with rectangular and square cross sections, which are excellent for wing spars. They are also much heavier than balsa, but with thier strength, you can substitude balsa spars for thinner spruce spars during desigingor re-designing. The most important property it has to me is that they are very much less prone to warp by climatic changes. Most of them remains straight and true after arriving to countries with wet climate like ours. For that reason, I always try to use them for wing spars in my designs.
Plywood : Model aircraft grade plywood is made of birch and is very dense and strong. The co-called 'lite-ply' is actually made of Poplar which is much weaker. Use them wisely. Actually, 'lite-ply' is not as useful as the former, apart form being easiest to cut with the penknife. Because it is weaker, you'd need to use more of them to achieve the required strength, resulting bigger and more parts. Compared to 'lite-ply' which often come in 1/8" thick, a 1/16" birch ply would do the job.
Although birch ply is harder to cut with a penknife than the 'lite-ply', be smart and don't be so quick to think that you'll need but a bench saw to cut it. You can simply substitude a part that is cut from a thick birch plywood by cutting 2 or more pieces of it out of thinner plywood. It may not save you time, but can save you tonnes of cash of buying a bench saw and stocking up plywood sheets of so many thickness. I only buy plywood up to 1/8" as I seldom need anything thicker than that and they can still be cut with a heavy duty penknife. The most useful size for small time scratchbuilder is 1/16" birch ply.
Plywood is commonly use to making stress bearing parts like fuselage doublers, fuselage bulkheads, engine firewalls and dihedral wing joining braces.
Basswood : Basswood is something between spruce and balsa. It is soft enough to be cut easily with a hacksaw, carved with a penknife, and yet strong enough to be used as wing and landing gear mounting blocks. However, they are not considered as one of the primary materials on aeromodelling although many find them very useful for certain dedicated purpose. Art Friends at Bras Basah complex stock up quite a selection of them.
Hardwood : There are many types of hardwood and they are generalised in aeromodelling uses. Hobby shops which sells aeromodelling prioducts simply call them hardwood and folks will understand that there are to be used for engine, wing and landing gear mount. Many types of wood are classifed within and sometime even basswood are packed and sold in this manner. They usually come in 12" long with square or rectangular cross sections.
Balsa : Needless to say, this is where everything got started. Commercially, balsa sheets are the primary material for flying model planes. They usually come in 3" wide by 36" long sheets. Commonly used thickness are 1/16, 3/32", 1/8", 3/16" and 1/4" sheets. 3/8", 1/2" and the thicker ones are used mainly for bulky parts usually carved to final shapes. Balsa is very prone to warp due to climatic changes. Choose your balsa carefully. If the material is meant for wing spars, LE and TE which alignment is very important, choose the straightest one you can find.
Balsa blocks are also available for solid components like nose cones and wing tips. However, you don't always need to use them. You can always explore the alternatives like laminating thinner sheets of balsa to get the correct thickness, rather than stocking up piles of balsa of different sizes. Also, balsa blocks often needs to be saw as penknife would be impractical to cut them properly. Making up parts from laminations saves you money and trouble to getting a bench saw.
Besides sheets and blocks, balsa sticks are also very useful for wing spars, leading and trailing edges, fuselage stringers and longerons. Available cross sectional shapes includes round, square, rectangular, triangular and wing leading and trailing edge profiles.
Not all balsa sheets and blocks are create equal. They come in different grade and weight and you should use them wisely according to thier properties. We generally grade them as soft, medium and hard. Soft balsa should be used for bulky parts or sheetings which strength is not the main concern. Wing sheetings, nose cone blocks and wingtip fairings should use soft balsa. Medium grade balsa are use generally on most parts of the airframe structural members which creates the shape like fuselage formers, side panels and wing ribs. Hard balsa is use for structural members which carry most of the airframe loads like wing spars and fuselage longerons. Some designs uses hard wood instead of balsa for such purpose.
Spruce : Spruce are dense hardwood, but soft enough to be shaped with a penknife and a junior hacksaw blade. They come in sticks with rectangular and square cross sections, which are excellent for wing spars. They are also much heavier than balsa, but with thier strength, you can substitude balsa spars for thinner spruce spars during desigingor re-designing. The most important property it has to me is that they are very much less prone to warp by climatic changes. Most of them remains straight and true after arriving to countries with wet climate like ours. For that reason, I always try to use them for wing spars in my designs.
Plywood : Model aircraft grade plywood is made of birch and is very dense and strong. The co-called 'lite-ply' is actually made of Poplar which is much weaker. Use them wisely. Actually, 'lite-ply' is not as useful as the former, apart form being easiest to cut with the penknife. Because it is weaker, you'd need to use more of them to achieve the required strength, resulting bigger and more parts. Compared to 'lite-ply' which often come in 1/8" thick, a 1/16" birch ply would do the job.
Although birch ply is harder to cut with a penknife than the 'lite-ply', be smart and don't be so quick to think that you'll need but a bench saw to cut it. You can simply substitude a part that is cut from a thick birch plywood by cutting 2 or more pieces of it out of thinner plywood. It may not save you time, but can save you tonnes of cash of buying a bench saw and stocking up plywood sheets of so many thickness. I only buy plywood up to 1/8" as I seldom need anything thicker than that and they can still be cut with a heavy duty penknife. The most useful size for small time scratchbuilder is 1/16" birch ply.
Plywood is commonly use to making stress bearing parts like fuselage doublers, fuselage bulkheads, engine firewalls and dihedral wing joining braces.
Basswood : Basswood is something between spruce and balsa. It is soft enough to be cut easily with a hacksaw, carved with a penknife, and yet strong enough to be used as wing and landing gear mounting blocks. However, they are not considered as one of the primary materials on aeromodelling although many find them very useful for certain dedicated purpose. Art Friends at Bras Basah complex stock up quite a selection of them.
Hardwood : There are many types of hardwood and they are generalised in aeromodelling uses. Hobby shops which sells aeromodelling prioducts simply call them hardwood and folks will understand that there are to be used for engine, wing and landing gear mount. Many types of wood are classifed within and sometime even basswood are packed and sold in this manner. They usually come in 12" long with square or rectangular cross sections.
...the only diving I've seen Joe make is when he 'DIVES' his glider !
...sorry, just got to add my 1 cents 
while permit.
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