Leading edge thickness

[n6346m]

What is the leading edge thickness for the B and F series airplanes? Are they all the same ? Has anyone used a thicker metal for the area in front of the wing tanks?

Bob Picard

[Robert Lees]

To the best of my recollection, it's 0.025" 2024 for the post-war aircraft. I believe some pre-wars used 0.016" Full span.

Why would it be needed to be thicker in front of any wing tanks, Bob?

Rob

[n6346m]

The usual reasons like banging the leading edge with ladders, fuel nozzles, dragging hoses, heavy fuel cans, errant elbows etc. you know , the usual stuff.

[Hank Jarrett]

Not from analysis, just from observation of damage to planes leading edges, Bob is probably right. I haven't seen any planes where the top LE skin was wrinkled from normal flight loads (usually would cause diagonal waviness if it was over stressed in wing bending) but I have seen some dents and minor damage in front of the fuel cap on the wings. Don't remember seeing it on the wings without tanks in them.

Only thing I would wonder is why they didn't put the thin skins on all but the inner most leading edge skins where the damage resistance was needed. Every pound left out of a Taylorcraft makes for better performance.

Again, I did NOT do any engineering or loads calculations, just from looking at wings.

Hank

[astjp2]

Drawings say .012 or was it .016 Nicral

[astjp2]

What is the leading edge thickness for the B and F series airplanes? Are they all the same ? Has anyone used a thicker metal for the area in front of the wing tanks?

Bob Picard

I went with .020 for most of the span and .025 in front of the tanks. T3

[Robert Lees]

The span-wise leading edge skins are about seven feet from the root to the first of two joints. This is well beyond where the wing tanks are.

There is no reason to think that the leading edge skins were thicker inboard, particularly bearing in mind the wing tanks are protected by the front spar! If you rely upon "line boys" to fill the wing tanks, leading edge damage is the least of the worries!

[n6346m]

I just looked up the drawing for the leading edge material for the DC-65 and it is .0125 NICRAL. I have no idea what nicral is and really couldn't find any reference to it online except for some magic aerospace stuff called nicral foam. I don't think that is what was used. Nicral could be an acronym for a nickel-chromium alloy which may have been applied as a coating like some electroplating process on some mysterious substrate. I just don't know. If anyone out there in Taylorcraftland knows what it is please let me know.

Bewildered Bob

[Scott]

I believe Nicral is 6061T6 or close equivalent

The skins I replaced on my BC12D were original and .020. I used 2024T3 025". If I was going to do it again I would use 020".

025 is difficult to bend. I made a bench-edge brake using door hinges, and then sucked them around a 1.5" diameter pipe with a shop vac. That still wasn't enough to get them to fit snuggly on the ribs using reasonable pressure with cargo straps. Had to form them some more on the bench brake before getting a good result.

If you need more strength in the fuel tank area add some angles (stiffners) between the ribs (like the one at the strut attach location) in that area.
S

[Hank Jarrett]

A few thin angle stiffeners between the root and first rib under the thin skin would be lighter and stiffer than a thicker skin! Great idea!!

Hank

[astjp2]

Nicral is Nicole cromium aluminum, easy to fill form back in the day. Use a real piper rib to splice prewar ribs. Perfect fit

[astjp2]

A few thin angle stiffeners between the root and first rib under the thin skin would be lighter and stiffer than a thicker skin! Great idea!!

Hank

My WW2 Jerry cans feel that .032 will barely support the weight when filling the wing tanks. I used well pipe to bend my leading edges into a wood former. Worked nice to make a 95ish degree bend for the leading edge. Tim

[Mark Bowden]

Nicral was a tradename just like Duraluminum before "aluminum" became "aluminum" and the current numerical alloy designation system came into use.

I have a paper somewhere on a study of pre/early war original alloy parts trying to figure out the chemical content of the trade name materials. I believe most of the conclusions were that the metallurgy process control technology at the time make it difficult to narrow things down and samples are very hard to come by as it is destructive analysis. I'll try and find it out of the files this summer.

[astjp2]

Duraluminum is the predecessor to 2S which became 2024, it was the primary material in the Ford trimotor, met a man who worked on them back in the 90`s

[Scott]

Duraluminum is the predecessor to 2S which became 2024, it was the primary material in the Ford trimotor, met a man who worked on them back in the 90`s

What was mostly missing from the trade names was the condition, ie hardness/temper of the material

2024, 6061, 7075 are available in several different hardnesses. There is a huge difference in the strength and behavior over the hardness ranges.

Piper appears to have used nicral for truss ribs, but it's not soft like 6061-T0. 6061 T6, which is what they used for spars, is much harder and I believe considered to be close to nicral.

Duralumin was aluminium alloyed with copper and the heat treated (to a hardness mostly known to the producer).

2S = 2 is copper as the alloying element and S means wrought ie '0' condition. So 2S would be similar to 2024 T0. In this condition it's no good for structure or stressed skin.

24st is the predecessor to 2024T3 largely regarded as the current dural equivalent and extensively used for structure and skins.

The really great thing about these heat treatable alloys is that you can fabricate complex parts, with tight bend radii, compound curves etc. when they're in the '0' state and then heat treat to T3, 4,6 etc for strength far superior to, for example, 3003H14.

Spar caps, float keels, that type of primary structure is often fabricated or extruded from 7075 and heat treated to T6. Higher strength than chromoly at a fraction of the weight.

Nicral..... 6061T6 is not used often in aircraft construction anymore. 2024 T3 became the predominant material.