Props without pressure ?

[King]

"The inability to feather a prop is what killed Rick Brickert in the Pond racer (Dick Rutan said that with a windmilling failed engine the Vmc was 160KIAS and the rate of descent with full power on the good engine would be 1600 fpm, which explains why Rick had to go to idle on the good engine and land in the sand. The picture of the wreckage in the Reno Gazette-Journal clearly shows the failed engine prop in flat pitch-I have the picture). "

Partly true but the inability to feather the prop is not what killed Rick Brickert.

The right engine failed and abruptly stopped in the unfeathered position. Rick came abeam the numbers and put the gear down and then raised the gear back up. The prop did not keep him from making the turn to the runway and cause him to go into the sagebrush.

There was an in-flight fire in the cockpit and it is believed that Rick was just trying to get the thing down on the ground as soon as possible. He did not die from ground impact, or officially known as blunt force trauma, he died from thermal burns from a fuel fed fire in the cockpit.

[Howard]

Maximum prop pitch...

King, sounds like you might be in a position to know.... just how big that bite might get... prop is an airfoil and must not stall when subjected to the "relative wind".. was trying to envision what happens when the pitch approaches 45 degrees. The thrust developed would appear to be greatlly reduced while the force required to rotate the prop would go up.... sure would appear to approach a situation of greatly diminished return of thrust... which is probably just what happens; needs lots of horsepower. This would all be limited by the loss of efficiency as the prop goes supersonic... I don't guess they will go much faster...

[Ron101502]

I guess I didn't explain what I was trying to say clearly enough. From the 2 eyewitnesses I talked too, coupled with the Pond's single engine performance I heard Dick Rutan describe at Oshkosk, speculation (and that's all it is since there is no way to know for sure) that since the prop didn't feather the only way to get down to a decent landing speed which was probably 100 KIAS or so and also to get closer to best glide speed which was probably less than 160kias was to pull off power on the good engine so the airplane would fly straight since Vmc at full power on the good engine was 160kias, and that explains why the fastest way to get on the ground was not on the runway.

The picture I referred to clearly shows to prop blades on the failed engine in flat pitch and all blades missing from the good engine which implies it was turning on impact.

Hindsight in this case isn't necessarily 20/20 but it MAY have been possible to keep enough power on the good engine with the bad one feathered to make the runway. That was the impression I got listening to Dick at OSH but that was a month before the accident. Maybe that wouldn't have made a difference.

I think the main point of this whole thread is if, in the name of safety, a full feathering prop on unlimiteds would be feasable or affordable, and if so, should such a system be required.

As one who has no prop warbird, round engine or big piston experience I can only relate to past experience with light twins and turboprops including a stint as a maintenance test pilot on the OV-10 and captain on a CV-580, none of which may be relevant to this discussion but leads me to belive a feathering prop would help engine out performance, especially if the engine failed in a low energy situation. But since the guys with the biggest interest, the race pilots themselves, haven't raised the issue then maybe it's not a big concern since most maydays happen at high airspeeds with plenty of energy to land safely.

[Unregistered]

"But since the guys with the biggest interest, the race pilots themselves, haven't raised the issue then maybe it's not a big concern..."

Let's be careful here. Three years ago I took a hard stand for extraction seat technology to the derision of many on these boards (the articles are still available on this site). The program I was involved in has been discontinued, however the need for extraction/ejection seat technology in air racing remains.

All of the negative comments I received on this subject were both public and from non- race pilots. When questioned privately, every single race pilot I spoke with said it was a good idea and that they would prefer to fly with, rather than without, an extraction seat. Few would come out publicly with this opinion due to the derisive nature of the boards and for fear of negative press.

We have to be careful forming opinions of what is best for the sport in a forum that is not dominated by the participants; i.e. race pilots.

I am a pilot, though not a race pilot. I have however raced motorcycles (AFM 5 years, AMA 3 years), carts, and hydroplanes (2.5l inboard). I believe that opinions on safety and racing issues should be tempered with the position of the person offering the opinion. No, I do not think that crew members have any special voice over the racers themselves.

I stand by my previous statement that auto feather should be mandatory for all variable pitch props on race planes. Especially in the event of engine or other failure.

Eric Ahlstrom

[Unregistered]

Originally posted by Unregistered
Sorry guys, you are not looking at picture of a feathered prop, but of one that´s taking the bite required.

If you think about it, how much pitch would it take to absorb that much HP?

My understanding of how prop governors work leads me to believe that if the pilot did *nothing* after the engine failure at full power, the prop blades wouldn't end up at full power pitch but more nearly flat. The reason being that the prop governor tries to maintain the set engine RPM at all times. Just before the engine failure at race power, a "deep" pitch (nearly feathered, but not there) would be required to absorb all the torque and hold the RPM down to the set point and prevent the engine running away, and also produce maximum thrust. But the moment the engine fails, the torque disappears and RPM starts to drop and the automatic governor does exactly the opposite of what you'd want it to do- it begins to flatten the pitch in order to unload the engine and keep the RPM up. To wind up anywhere near the full-power or feathered positions rather than flat, the pilot would have to take over and manually feather the prop, and the prop control system would need to continue working long enough to complete the feathering operation. The very fact that September Fury's blades wound up anywhere close to being feathered (and reports said that the engine quit rotating completely right after touchdown) implies to me that Brown had time to move the lever, and that the system was still working despite the gaping hole in the engine.

Eric, King, or others in the business... isn't this about what would happen with the Aeroproducts prop?