Wooden Airframes

Mike Fawdrey · Post by **Mike Fawdrey** » Sat Feb 07, 2009 12:13 pm

Hi Folks,
I am currently reading a book on airplane maintenance, I wondered why ash is not used for wooden airframes.
Before the second world war many motorcars used ash frames to build lightweight motor cars. Can anyone comment please.

Bill McCarthy · Post by **Bill McCarthy** » Sat Feb 07, 2009 2:46 pm

Might have something to do with weight and grain structure.

Brian Hope · Post by **Brian Hope** » Sat Feb 07, 2009 5:01 pm

Hi Mike, ash is heavy and dense. It is used for load bearing blocks, such as at an engine mount location, but not as a general airframe material, where spruce and douglas fir are popular choices.

macconnacher · Post by **macconnacher** » Sat Feb 07, 2009 5:03 pm

It is strength v weight that is ithe reason. Spruce is very good and is very straight grained. Most wooden aircraft use some ash where strength and crush resistance is important like the uprights in the front bulkhead of a Taylor Monoplane to which the engine is bolted.

In WW1 I am sure most Sopwith types had ash longerons with wire bracing and even then the ash is machined with a router to cut down on weight but for the usual DH ply box construction which we use in most homebuilts ash is too heavy.

Mike Fawdrey · Post by **Mike Fawdrey** » Sat Feb 07, 2009 9:44 pm

Many thanks for that information gents, I dont build airframes but as a retired engineer I am always intrigued by the reason why things are so.
Regards Mike