F1 control stick material
Bob,
I didn't measure the tubes but I think they were 1" and the wall thickness seemed about normal, nothing very beefy. The arrangement was the same as an RV where the stick fits into a receptical near the base where the pivoting occurs and the receptical was steel, just the sticks were aluminum with a slight gentle bend. Perhaps someone more familiar with F1's could comment.
The sticks are made from 7/8 x .049 wall 6061T6 tubing. I use a 2' extension to form 'em around a die; the material is very stout. Forming those parts wears me out pretty quickly. The lower pivot is made from 1" x .058 wall 4130 - also a very tough part.
Before you start in with the advantages of 4130 (the RVs use 1" x .035 wall to the best of my knowledge - user comments welcome), best you make yourself aware of the stick failures in the welded assemblies -- there are quite a few, ranging from bad welds to simple cyclic overloads.
The Sport wing ships have about 6lbs/G stick forces. So, max G takes about a 36lb pull on the stick -- not very much. I will suggest that the stick will last forever with this being the case, even with a wiring hole just above the socket.
Something else is involved in this crash -- my feeling is that the broken stick is a symptom, not a cause.
Test sequence for any of you to perform: put your ship in a 20-30 deg dive (from a reasonable altitude, please), leaving the trim set as it was in level flight: just push over using the stick. Your ship should start to pitch up (hands off) after accelerating ~20MPH or so. The ship should not descend much more than 500' before it recovers on it's own. Obviously, this ship did not do that, and the question is why.
My ship is an Evo, with a completely different foil, so I cannot perform this test: the Evo foil has just enough pitching moment in its foil to allow a very wide trim band (pitch neutral), whereas the 23013.5 on the RV4/6/7/8 & Sport wing F1s have a more positive pitch response, forcing the nose up due to it's much narrower trim band. Neither trait is better then the other, unless you prefer, or do not prefer, a ship that needs less trimming in its normal speed ranges. You can read Doug Rozendaal's F1 flight report on the Team Rocket website for a description of how this feels to the pilot.
The NTSB will have a look at the wreckage this week -- I talked to the inspector last week, and he knows his stuff. We'll have a better picture soon enough, so please stand by.
Carry on!
Mark