Art Field
What do you know about the Valiant wing spar failure at Gaydon? Did the wing seperate?
On 29/4/57 The second Valiant prototype -215- had developed a fatigue crack in the bottom main spar cap through about 30% of its cross section. The rest broke under the stress of an AUW flight at 210 KIAS and about 20 degrees of bank in slight turbulence preceding the first seperation trials of two Super Sprites that had just been fired to measure take off performance.
We were carrying two 1600 gallon tanks filled with jettisonable water and another 1,000 gallons in the weapons bay to get to about 170,000 pnds AUW. The Super Srites gave us an extra 8,000 pnds of thrust over about 50 seconds for the measured take off.
The spar let go with a terrific bang and shock and the Valiant started to roll into the broken wing. This trimmed out OK and we three on board believed that our chase Meteor 7 had rammed us. Its pilot reassured us to the contrary so the next surmise was that one of the Super Sprites had not completed its purge of its excess High Test Peroxide oxident which may have exploded. One SS we had on closed circuit TV looked alright so we went ahead with individual seperation trials without delay and commenced water jettison, wanting to go to ground ASAP. We drenched Boscombe Down's runway and taxiways with water and considerable relief to be down but still not knowing what diabolical thing had occurred.
The fracture of the spar was soon located at the focus of pulled wing skin rivets and skin shedding just aft of the R main wheel well. Following defuelling and jacking with wing jacks the spar opened up with a gap of about an inch so that we could examine the fracture surfaces. The tide marks of fatigue crack growth were obvious and the remainder of the spar had broken under tension. The gap in the spar in flight was about 2 inches which would have extended the dihedral by about 3 degrees.
We had been saved from wing seperation by a steel cross brace extending from the top of a forward sub-spar to the main spar bottom cap outboard of the break.
In retrospect, if we had known that a wing spar had broken, we would not have jettisoned the water from the underwing tanks as their weight outboard would have been relieving moments on the wings. But perhaps instead we would have given our FTE an opportunity to use his parachute before leaving the only surviving prototype to her own devices.
I guess 215 eventually went to the recyclers!