THE ENGLISH LONG BOW.

[Teisani]

Originally Posted by Peter Hudson

I have always wondered what the effect is when arrows are greased before firing? Something tells me that the speed is either maintained better or increases the hitting power when goosegrease is put on the arrows...somehow preventing friction thus increasing delivery speed to the target...suggesting it was better for armour penetration... but I have no direct evidence to quote ...it being something someone said once? Can anyone throw some light upon this ?

Regards,
Peter Hudson.

Making a suface greasy or non-stick doesn't necessarily reduce it's friction drag (viscous drag). If it did we would coat airplanes with teflon and save a lot of money in kerosene. So any improvement that you would see will not be due to drag reduction.

Aerodynamic drag in the low subsonic speed range that arrows travel in, is due to 2 reasons: viscosity of the air and longitudinal pressure distribution over the arrow.
The viscous part is due to the air sticking to the exposed surface of the arrow. So to reduce viscous drag you need to reduce this wetted area in ratio to the arrow's mass. Or change the material to a higher density. Like kinetic armour piercing rounds APFSDS for tanks use depleted uranium or tungsten due to their high density. Of course you will need to use a stronger bow to maintain initial velocity. Coating with a lubricant will not work.
The pressure drag is due to high pressure in the front, and a low pressure wake developing in the rear. For an example of a optimized shape, look at a symmetric airfoil. Blunt in the front (required for wings but not for arrows) and long gently tapering back (always a necessity).

So, for a medieval archer to improve, I strongly recommend a research and development programme in the field of computational fluid dynamics and material science, towards the development of depleted uranium arrows of an optimized cross-section distribution. Oh, and to train more, so he can chuck the damn things with gusto. I don't know... maybe hit the gym.

[Peter Hudson]

Seems like more to it...and I dont actually know but I suspect it may not be grease on the arrows that makes the difference... Rethinking this perhaps its nothing to do with the speed of the arrow and only connected to the warhead... Thus I rewrite the question as ... Does greasing the warhead improve armour penetration?

Peter Hudson

[Teisani]

Originally Posted by Peter Hudson

Does greasing the warhead improve armour penetration?

On soft wood shields, greasing the shaft, Tod suggests it does help by reducing friction beteeen the shaft and shield https://m.youtube.com/watch?v=56ijR7aPy3U
On steel armor, I doubt it gives any noticeable improvements. But until somebody tests it we won't know.

[Peter Hudson]

Yes I read yesterday about this and was about to reply to Forum having watched every video available ...Tod did a couple of them and when he was about to fire and compare greased shafts onto armour the whole computer system crashed..Now its back up ... maybe we shall see the result... I knew about this vaguelly a decade ago and the rumour was it was Goosegrease ... although no one knew for sure... Against the wooden shield bonkin arrows go in twice the penetration of ungreased war heads... so it looks very promising. I recall Tod mentioning that they used beef fat ... although it was said just as a passing remark about arrows not part of a concentrated study... Now he is on to a proper study we should see a result...

Peter Hudson

[Peter Hudson]

Specifically on the English Longbow regarding Bodkin and Needle Bodkin arrows.

Reference http://www.vikingsword.com/vb/showth...t=goose+grease the same question was raised ...at #25 thus here it is again

Does greasing the warhead improve armour penetration?

Peter Hudson.

[Peter Hudson]

Originally Posted by Teisani

Making a suface greasy or non-stick doesn't necessarily reduce it's friction drag (viscous drag). If it did we would coat airplanes with teflon and save a lot of money in kerosene. So any improvement that you would see will not be due to drag reduction.

Aerodynamic drag in the low subsonic speed range that arrows travel in, is due to 2 reasons: viscosity of the air and longitudinal pressure distribution over the arrow.
The viscous part is due to the air sticking to the exposed surface of the arrow. So to reduce viscous drag you need to reduce this wetted area in ratio to the arrow's mass. Or change the material to a higher density. Like kinetic armour piercing rounds APFSDS for tanks use depleted uranium or tungsten due to their high density. Of course you will need to use a stronger bow to maintain initial velocity. Coating with a lubricant will not work.
The pressure drag is due to high pressure in the front, and a low pressure wake developing in the rear. For an example of a optimized shape, look at a symmetric airfoil. Blunt in the front (required for wings but not for arrows) and long gently tapering back (always a necessity).

So, for a medieval archer to improve, I strongly recommend a research and development programme in the field of computational fluid dynamics and material science, towards the development of depleted uranium arrows of an optimized cross-section distribution. Oh, and to train more, so he can chuck the damn things with gusto. I don't know... maybe hit the gym.

Thanks for the reply; I do recall reading about a Turkish Footbow that fired arrows that had no flights but the shafts were tapered i.e. thicker in the middle and pointed at both ends like an aeroplane fusilage today... and achieving incredible distance far better than any other bows...

Regards, Peter Hudson.