Motor wound up tight

[N801BH]

Here is a link to a video of the Reno air races when Relentless blew up.

Ted should get a kick out of this as he is a fellow motor guy.

About 8 seconds in the prop leaves, because of the time it takes sound to travel a second or so later you can hear the motor rev up to god only knows what rpm. Any true motor heads can to guess how high it buzzed up to.

ps. I am not sure if laptop speakers can produce the actual sound but on my home puter it is unbelievable.

http://www.youtube.com/watch?v=DhyEnqudx8M&feature=player_embedded

 

[gismo]

Here is a link to a video of the Reno air races when Relentless blew up.

Ted should get a kick out of this as he is a fellow motor guy.

About 8 seconds in the prop leaves, because of the time it takes sound to travel a second or so later you can hear the motor rev up to god only knows what rpm. Any true motor heads can to guess how high it buzzed up to.

ps. I am not sure if laptop speakers can produce the actual sound but on my home puter it is unbelievable.

http://www.youtube.com/watch?v=DhyEnqudx8M&feature=player_embedded

Yeah, the sound of the unloaded motor was quite obvious on my laptop, I can't imaging what it sounded like in the cockpit though. Seems to me he was rather fortunate in that both blades departed almost simultaneously which may have limited the abuse normally associated with a prop failure.

From the pitch of the sound I'd guess that the engine reached approximately twice normal RPM in less than a second before self destructing. I do wonder what came apart in the engine? I can't imagine that the pistons and con-rods could tolerate that kind of abuse but it's typical that the valves will begin to float (stay open) somewhere between 125 and 150% of max rated RPM. If the floating valves could contact the pistons that might cause enough localized damage to cause a total loss of power before the reciprocating parts came to pieces.

 

[N801BH]

I am guessing it got to 5200-5500 before it let go..

I am betting the plane was fitted with data aquisition and the real rpm will eventually be disclosed.

I have a whole new respect for Lycoming engines after seeing the remains.

Ted and company should be quite proud of its durability.

There is a ongoing discussion on another site that has pics of the engine and prop.

http://www.backcountrypilot.org/forum/viewtopic.php?f=16&t=6117

Ben.

 

[BillTIZ]

The report on another forum from the flight team. Oil pressure line failed, possible AN fitting, and pressure to the Prop govenor was lost, blades went flat pitch and the engine revved instantly. It came apart inside, blew a jug and the case and siezed. The blades snapped off from the instant stopping of rotation.

 

[gismo]

I am guessing it got to 5200-5500 before it let go..

I am betting the plane was fitted with data aquisition and the real rpm will eventually be disclosed.

Unless the data acquisition was running an unusually high rate (quite plausible given the short duration of the flights) it might have missed the overspeed almost completely. One sample set per second would be totally inadequate, 50 Hz probably overkill.

 

[Henning]

It sounded pretty cool live. I thought someone had hit an air starter.

 

[Henning]

The report on another forum from the flight team. Oil pressure line failed, possible AN fitting, and pressure to the Prop govenor was lost, blades went flat pitch and the engine revved instantly. It came apart inside, blew a jug and the case and siezed. The blades snapped off from the instant stopping of rotation.

Broke the cam as well, but the blades came off before the overspeed that broke the engine. I looked at all the parts on the ground there in the pit, and I question that analysis.