Dreadnought Out

Dreadnought safely back in its pit after giving everybody a huge scare this afternoon.

We had just arrived at Reno-Stead Tuesday afternoon and were standing at the trunk of our car putting on our photo vest when crowd favorite Dreadnought entered the race course. Looking to post a qualifying time, the massive Unlimited with the even larger Pratt & Whitney R-4360 swung down from altitude and disappeared from our view headed north to start a lap.

A moment later you could hear Dreadnought coming back to our south end of the course when suddenly a loud, continuous “wuuf, wuuf, wuuf, wuuf” cadence sounded out over the 28-cylinder engine’s exhaust note. All other background sounds at Stead stopped as everyone looked to the big Sea Fury zooming heavenwards off the front straight trailing moderate smoke and wuufing like a wounded steam engine. I immediately thought of a nasty expletive but some guy nearby shouted it out.

With my view blocked by hangars I couldn’t see the outcome of Dreadnought’s diving turn to a runway, but knew pilot Joel Swagger was earning his keep. I could only wish him luck and knew I’d have to get credentialed just to get in the gate and then walk all over the airport before getting accurate word on the outcome.

Luckily we found Dreadought sitting in apparently one piece in its pit. There wasn’t even a small lake of oil dripping underneath it, the normal outcome of a “windowed” engine. A crew member reported that Swagger said the engine felt strangely off or lazy—but smooth—while entering the course today, only later backfiring violently, making that wuuf, wuuf, wuuf sound everyone heard.

No one knows what let go inside the engine, but the best guess is a cylinder dropped an intake valve. That opens the engine inlet tract to the furious maelstrom of air and fuel being pounded between a huge supercharger huffing away and the valveless cylinder chuffing the other direction. Mayhem ensues and backfires are the result.

And don’t misunderstand, a 4,360 cubic inch supercharged engine continuously backfiring is near bomb-like in intensity. Many aircraft have been lost or heavily damaged this way, and one look at Dreadnought’s deranged engine air inlet in the photo tells the story. The “Buick” is obviously built tough.

Normally the engine air inlet atop Dreadnought’s cowling features a smooth curve. The central peak and tears in the two corners are from today’s backfiring; moot testimony to the violence of sneezing large, supercharged engines at high rpm and load.

Dreadnought is, of course, hors de combat at this point and sadly will not participate in these final Reno races. That’s a shame for those coming to see it run, but the good news is it’s all repairable and we haven’t seen the last of Dreadnought.

As to what failed in the incredibly complex Pratt & Whitney, we’ll report anything official we hear once the crew opens the engine for inspection. This is most decidedly not the work of a moment and might well take place in a cozy Stead hangar long after the races are over.

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Tom Wilson
Pumping avgas and waxing flight school airplanes got Tom into general aviation in 1973, but the lure of racing cars and motorcycles sent him down a motor journalism career heavy on engines and racing. Today he still writes for peanuts and flies for fun.


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