empennage rib material

[boba65$#]

Hey guys........just found a "curiosity ".on plans pages......23,24,25,26. On page 23 it lists the rudder ribs  being constructed of 4130 steel.......and on pages 24 and 25, it lists the "fin", and "stabilizer" ribs being constructed (typically) of .024 "mild steel". Also on page26 it lists elevator ribs being constructed of  .024 "mild steel". Been a long time since A&P school. but if I remember 1020(ASTM) is "mild steel", whereas 4130 is a true "alloy" with stuff like Carbon,Chromium,Manganese,Molybdenum,Silicon, and traces of Phosporous.. Not trying to dance-on-a-razorblade....but I'm under the impression that locally sourced "Home Depot" steel from the DIY display would be OK for all EXCEPT the RUDDER? OR, should I spend about $20 more from Aircraft spruce and just do the whole lot in 4130??? What did you use.......and........any problems/or changes that you would make if you were to do it again??. Thanks!!! BOB in Idaho

[MrG]

Mines all chrome molly and i wish down under here it was only $20 more - Only gotcha is the horizontal stabilizer in the drawings shows as level
it actually sites on the plane about 1 - 1 1/2 inches down at front to get the correct flight angle and remove back stick forces - hence the mount blocks if made
vertical will have tension on them - if you need a photo let me know

[boba65$#]

Mr G.........thanks for the input brother...I think I saw one of your "modifications" postings that detailed what you are talking about regarding the Horizontal Stab. You had some pics which depicted a more "downward" attach point of the Stab...probably giving you a bit more pitch-up moment @ landing vs. a bit more throttle @ flare? BOB

[scottiniowa]

Hey guys........just found a "curiosity ".on plans pages......23,24,25,26. On page 23 it lists the rudder ribs  being constructed of 4130 steel.......and on pages 24 and 25, it lists the "fin", and "stabilizer" ribs being constructed (typically) of .024 "mild steel". Also on page26 it lists elevator ribs being constructed of  .024 "mild steel". Been a long time since A&P school. but if I remember 1020(ASTM) is "mild steel", whereas 4130 is a true "alloy" with stuff like Carbon,Chromium,Manganese,Molybdenum,Silicon, and traces of Phosporous.. Not trying to dance-on-a-razorblade....but I'm under the impression that locally sourced "Home Depot" steel from the DIY display would be OK for all EXCEPT the RUDDER? OR, should I spend about $20 more from Aircraft spruce and just do the whole lot in 4130??? What did you use.......and........any problems/or changes that you would make if you were to do it again??. Thanks!!! BOB in Idaho

This must be for a DE?   But for a breakdown, I think the thinnest 4130N sheet steel is .025,  only a thou difference, but like you say "dance on a razorblade" deal here we are talking.  I find quite a difference in the two materials, for something like this.

But a quick calculation tells me the difference would/could be a lot more than $20 more.  If I am reading this correctly.  As always, lots of ways to go, but your first question is important for all builders following- Which is being called out..?

[boba65$#]

scottiniowa........thanks for your input...........so,as you point out....maybe I undershot the price diff. All this being said, I ASSUME that the rudder itself (obviously) could recieve FAR MORE FLEX that the other surfaces. Weight difference is almost moot, so I'm gonna go with 4130 all-the-way. Cannot see that any weight  difference would be a factor. More rigid tail feathers support a better "feel" for the pilot, as a rule. Yeah, the .001 difference is non-issue. Decision made..........unless  there is an engineer in-the-crowd that can enlighten me as to why 4130 would be unsuitable for the others. Thanks again ! BOB

[boba65$#]

scottiniowa............yeah,forgot to mention. It is DE-95