Setting the record straight

[BellCobraIV]

Over the last few years I have made it a habit of not commenting on Rare Bear and it's current operations. Recently I decided to make a comment based on information that I thought was correct at the time.

I had a rather interesting conversation with John Penney the other day, The conversation started with regards to our mutual history with the Rare Bear and continued to include the events of the recent meltdown prior to last year’s air race season. Let’s just say that the public perception of what really happened is not complete, and in fact could be very wrong. I know thoughts that I had were changed after viewing the telemetry files, and listening to John’s explanation. Maybe John will come on and post his thoughts.

John

["Bear" Driver]

Re: Setting the record straight

OK, Thanks John. I’ve sat quietly by and occasionally perused the comments on another thread, many of which were posted by uninformed individuals who really didn’t know all the technical details and other armchair experts. Several people including Stew Dawson have urged me to set the record straight. I appreciate John Slack’s comments opening the door and suggestion to clear up the misconceptions.

When ready to start testing last year, a family medical emergency kept me at home that weekend, and Stew was also unavailable. Against the cautions of both Stew and me another pilot was paid to do some “shakedown” testing. Claims that data show really high speeds are not substantiated, as on the run referred to the camera quit before power was pushed up to set up for a straight, wings level run at power, most likely coming downhill. It was probably a fast run but the fact is, there are no data. Claims that the engine checked out healthy after the flight are also misleading as there was no post-flight leak down check according to one of the full time mechanics…just a run up and mag check.

Ever since the cowling was modified on the plane after 2007, reduction in airflow through the engine section has resulted in cylinder head temperatures that have butted right up against redline. Where I use to taxi out and have to wait several minutes for the CHT to rise enough to do a runup, now the CHT goes 200 degrees above that temp even before leaving the chocks to taxi out! This engine has a heating problem. When both Stew and I have pressed for something to be done to improve the airflow for cooling, we have been blown off, several times in an angry manner.

Last year, the crew chief started an experiment to cool the cylinder heads by leaning the carb mixture! When I arrived after the other pilot had flown, an even leaner mixture had been set which would raise induction temp even further. When told by the crew chief where the other pilot had the ADI adjustment set (that only fine tunes the ADI that the carb is already putting into the blower), I told him where I had it set (in anticipation of a higher induction temp due to an even leaner mixture and would work it in to get the right induction temp). No response. Maybe he didn’t hear me. And, contrary to what one armchair expert accused, I was never “told what to do”. Had I been, it would have been set exactly as instructed. I have always followed the crew chief’s instructions to the letter.

At the end of the day, I was accused of “throwing a slug of water” (ADI) to the engine that “warped the exhaust valves”. Some time later, one of the mechanics told me that in fact, no exhaust valves were “warped”, but instead there was displacement/deformation of the valve seats. Every engine builder, maintainer, and expert warbird restorer that Stew and I have talked to about this, to a one, say that too cool an induction temp does not warp exhaust valves, but that running cylinder head temps extrapolated to where they would have ended up on the “high speed run” certainly will warp and displace the valve seats in the aluminum heads…which is EXACTLY what happened.

The induction temp profile (supposed “thermal shock”), on my first test flight when bringing on the ADI was no different than that seen time and time again on the TM starting in 2007 with the ON/OFF ADI regulator that Stew and I don’t like versus the Greg Shaw regulator used in previous years on this plane. The crew chief had changed out that regulator that would bring on the ADI flow as manifold pressure is brought up, by his own ON/OFF regulator. His regulator throws a “slug of water” to the engine as soon as the switch is thrown. The induction temp data from Stew’s Sunday race shows the same “thermal shock” drop as on my test flight and all other race starts starting in 2007. Hmm…no damage…

In 2004, I had to run the whole “snowstorm” gold race at 40 degrees induction and again in 2005, the wrong “pill” was in the carb and the whole race was run at 50 degrees with the adjustment valve full closed. Strange…no damage to the engine!

On the other pilot’s high-speed run, CHTs were approaching redline (when the camera stopped), even BEFORE the power was pushed up. Data from runs I have made and from Stew’s racing show that at race power, even starting from a much cooler temp, the cylinder head temps track a straight climb right through redline with no tendency to level off. On Stew’s Sunday race, He had to pull the power back on lap two just to keep it AT redline. At race power (which is what the other pilot had set for the high speed run), Stew and I are in total agreement that CHT would have gone right through redline and just kept going.

Speeds? Yes the other pilot had a fast run in straight and level flight in air as “smooth as glass” as described by the crew chief. All of Stew’s and my runs were in 45 to 60 degrees bank (1.7 to 2 Gs), in hot air that was rougher than a cob. So comparing the speeds is comparing “apples and oranges”.

Stewart and I and many others are in firm agreement that what ruined all those cylinders was CHT going way above redline before my test flights.

Interesting that after Sunday’s Gold Race, one of the most highly respected elder statesmen of air racing, who had been working the carb mixture experiment with the crew chief, came up to Stew, apologized and acknowledged they were wrong.

Oh…the “slug of water” that I was accused of throwing at the exhaust valves; the math is straight forward and reveals that at race power ADI flow is about ELEVEN ONE THOUSANDTHS of ONE OUNCE per intake stroke (into the whole combustion chamber)!

Recently, Stewart and I and a very highly respected warbird restorer and air racer visited the “Bear” to determine how adequate cooling air can be reestablished through the engine section to get the CHTs back down where they belong.

[FlyKidChris]

Re: Setting the record straight

First, for both Johns, thanks for posting and setting the record straight. I'll wager that many other fans will feel the same.

I've been a die-hard Rare Bear fan since my first adventure to Reno and I'll remain a fan. While I root for all teams to do well, #77 is my #1.

So if the problem has been identified and is understood, I'm hoping for another run (of years) of very fast full race speeds for the Bear.

Good luck to everyone.

[jetwaste]

Re: Setting the record straight

John,
First words in 9 months.

[Lockheed Bob]

Re: Setting the record straight

Thanks to all for the inputs. Very informative & yes like NASCAR it does take a team to win at Reno. I'm a P51 person but we need them all to make a race & the "Bear" needs to be at its best to make it interesting. I hope they come up with the answer.

[RichH]

Re: Setting the record straight

JS & JP... thanks so much for the enlightenment. Wow.

Makes me wonder... if moving the firewall slightly aft as they did had that great of an effect on the airflow, or if it was more a matter of plugging something up that wasn't before. The only thing I've noticed externally is that there used to be a couple of vent slots it the exhaust troughs, which don't appear to be there anymore. Not like those vents were huge or anything... certainly not matching the volume exiting out the back on the Sea Fury implementations!

As far as not doing anything about such a problem, and for THAT many years, well... O_o

[marada mx3]

Re: Setting the record straight

"Ever since the cowling was modified on the plane after 2007, reduction in airflow through the engine section has resulted in cylinder head temperatures that have butted right up against redline."

Doesn't The Bear have a DC-something cowling now? If so, can the previous cowling be put back in place, or were too many mods made for that?

Thanks Johns!

[RichH]

Re: Setting the record straight

^^^ It has the same DC-7 cowl as before, except a new one was built up and lengthened due to the firewall being moved back.

[Dialtapper]

Re: Setting the record straight

Over the last few years I have made it a habit of not commenting on Rare Bear and it's current operations. Recently I decided to make a comment based on information that I thought was correct at the time.

I had a rather interesting conversation with John Penney the other day, The conversation started with regards to our mutual history with the Rare Bear and continued to include the events of the recent meltdown prior to last year’s air race season. Let’s just say that the public perception of what really happened is not complete, and in fact could be very wrong. I know thoughts that I had were changed after viewing the telemetry files, and listening to John’s explanation. Maybe John will come on and post his thoughts.

John

"Setting the record straight"? Really?

Fairytales are supposed to start out "Once upon a time"

Let's just cut to the facts here.

"I know thoughts that I had were changed after viewing the telemetry files,"

I've seen the "Telemetry files" you have. You have not seen any telemetry from the flight where the engine was damaged. There isn't any, it was not working on that flight.
Fortunately there was video, It leaves no doubt what happened.

"I know thoughts that I had were changed"

The thoughts of the six A&P Crew Members, (of which you are neither) that changed all 18 cylinders, have not changed. We all know what happened 9 months ago.

"Over the last few years I have made it a habit of not commenting on Rare Bear and it's current operations."

Good habit. Lets keep it that way.

[Dialtapper]

Re: Setting the record straight

OK, Thanks John. I’ve sat quietly by and occasionally perused the comments on another thread, many of which were posted by uninformed individuals who really didn’t know all the technical details and other armchair experts. Several people including Stew Dawson have urged me to set the record straight. I appreciate John Slack’s comments opening the door and suggestion to clear up the misconceptions.

When ready to start testing last year, a family medical emergency kept me at home that weekend, and Stew was also unavailable. Against the cautions of both Stew and me another pilot was paid to do some “shakedown” testing. Claims that data show really high speeds are not substantiated, as on the run referred to the camera quit before power was pushed up to set up for a straight, wings level run at power, most likely coming downhill. It was probably a fast run but the fact is, there are no data. Claims that the engine checked out healthy after the flight are also misleading as there was no post-flight leak down check according to one of the full time mechanics…just a run up and mag check.

Ever since the cowling was modified on the plane after 2007, reduction in airflow through the engine section has resulted in cylinder head temperatures that have butted right up against redline. Where I use to taxi out and have to wait several minutes for the CHT to rise enough to do a runup, now the CHT goes 200 degrees above that temp even before leaving the chocks to taxi out! This engine has a heating problem. When both Stew and I have pressed for something to be done to improve the airflow for cooling, we have been blown off, several times in an angry manner.

Last year, the crew chief started an experiment to cool the cylinder heads by leaning the carb mixture! When I arrived after the other pilot had flown, an even leaner mixture had been set which would raise induction temp even further. When told by the crew chief where the other pilot had the ADI adjustment set (that only fine tunes the ADI that the carb is already putting into the blower), I told him where I had it set (in anticipation of a higher induction temp due to an even leaner mixture and would work it in to get the right induction temp). No response. Maybe he didn’t hear me. And, contrary to what one armchair expert accused, I was never “told what to do”. Had I been, it would have been set exactly as instructed. I have always followed the crew chief’s instructions to the letter.

At the end of the day, I was accused of “throwing a slug of water” (ADI) to the engine that “warped the exhaust valves”. Some time later, one of the mechanics told me that in fact, no exhaust valves were “warped”, but instead there was displacement/deformation of the valve seats. Every engine builder, maintainer, and expert warbird restorer that Stew and I have talked to about this, to a one, say that too cool an induction temp does not warp exhaust valves, but that running cylinder head temps extrapolated to where they would have ended up on the “high speed run” certainly will warp and displace the valve seats in the aluminum heads…which is EXACTLY what happened.

The induction temp profile (supposed “thermal shock”), on my first test flight when bringing on the ADI was no different than that seen time and time again on the TM starting in 2007 with the ON/OFF ADI regulator that Stew and I don’t like versus the Greg Shaw regulator used in previous years on this plane. The crew chief had changed out that regulator that would bring on the ADI flow as manifold pressure is brought up, by his own ON/OFF regulator. His regulator throws a “slug of water” to the engine as soon as the switch is thrown. The induction temp data from Stew’s Sunday race shows the same “thermal shock” drop as on my test flight and all other race starts starting in 2007. Hmm…no damage…

In 2004, I had to run the whole “snowstorm” gold race at 40 degrees induction and again in 2005, the wrong “pill” was in the carb and the whole race was run at 50 degrees with the adjustment valve full closed. Strange…no damage to the engine!

On the other pilot’s high-speed run, CHTs were approaching redline (when the camera stopped), even BEFORE the power was pushed up. Data from runs I have made and from Stew’s racing show that at race power, even starting from a much cooler temp, the cylinder head temps track a straight climb right through redline with no tendency to level off. On Stew’s Sunday race, He had to pull the power back on lap two just to keep it AT redline. At race power (which is what the other pilot had set for the high speed run), Stew and I are in total agreement that CHT would have gone right through redline and just kept going.

Speeds? Yes the other pilot had a fast run in straight and level flight in air as “smooth as glass” as described by the crew chief. All of Stew’s and my runs were in 45 to 60 degrees bank (1.7 to 2 Gs), in hot air that was rougher than a cob. So comparing the speeds is comparing “apples and oranges”.

Stewart and I and many others are in firm agreement that what ruined all those cylinders was CHT going way above redline before my test flights.

Interesting that after Sunday’s Gold Race, one of the most highly respected elder statesmen of air racing, who had been working the carb mixture experiment with the crew chief, came up to Stew, apologized and acknowledged they were wrong.

Oh…the “slug of water” that I was accused of throwing at the exhaust valves; the math is straight forward and reveals that at race power ADI flow is about ELEVEN ONE THOUSANDTHS of ONE OUNCE per intake stroke (into the whole combustion chamber)!

Recently, Stewart and I and a very highly respected warbird restorer and air racer visited the “Bear” to determine how adequate cooling air can be reestablished through the engine section to get the CHTs back down where they belong.

The Crew Chief told you not to go above 90 or below 60C induction temperature.

Why didn't you follow his instructions?

[al baby]

Re: Setting the record straight

Why all this hand wringing over the Bear? We all know it belongs in a museum. The Bear, just like Dago has left it's better days behind. Everybody know that Rod's "A Team" is now 232. Go 232!!!

[toldjaso]

Re: Setting the record straight

wowee
Thank You for that, Dialtapper. You always did bring some common sense into the mix.
And thank You, Wayne, for editing my first response out, so as not to throw racegas onto the fire.

[Wild Bill Kelso]

Re: Setting the record straight

Why all this hand wringing over the Bear? We all know it belongs in a museum. The Bear, just like Dago has left it's better days behind. Everybody know that Rod's "A Team" is now 232. Go 232!!!

Well I heard they did get a new crew member over there

[AAFO_WSagar]

Keep Out Of It!

I just deleted a post in this thread... it was by a new user, first post and the poster came out swinging over something he or she probably has no first hand knowledge.

I'm going to post a request, this thread is now populated by several former crew members from the most recent crew, the former pilot is here as well.. so the players in this thread know what this is about... we don't... let's let this be their thread. Air needs to be cleared and all we can do is add our own second hand hot air...

If you weren't there, sit back and learn... if you were there, please be factual, polite and respectful of each other...

Thanks!

[dabshr]

Re: Setting the record straight

dialtapper post the video!