What just happened at Reno?

JDK · **Posted:** Tue Sep 20, 2011 8:33 am

What seems a good summary posted on Key by 'Canadair' - I don't recall it elsewhere, so I share it here:

Quote:

Just to add a comment regards trim and the effects on the course:
The racers are all trimmed prior to entering the course with a large nose up trim bias, the idea being as they approach the race speeds they can relax the push, as the trim will be correct for the speeds, 400 plus, so one less item to think about, in what would be a pretty intense environment.
The in flight speed range of GG would be about 140 kts to 500+ kts, so it is acceptable to preset a high speed trim, while still accelerating, compensating for the required push until on the course.

in racing, as opposed to most normal flying, the combination of the angle of bank and the need to fly a line with increasing speed means you are using bottom, not top rudder in turns, and you are pushing the nose down in a turn with rudder, and when straight with trim, (elevator) this is opposite to normal input but required for the course.

The downside is exactly what has now probably happened twice, if the trim lets go at speed, the now untrimmed elevator will bias due speed to where it would go if the trim was not applied, full TE up, (nose up effect), and this then creates a situation of "see what wins", with the options being, Flutter, control system structural failure, high speed stall, or full deflection, with resultant effect,
in this case it appears the elevator was powerful enough and mounted securely enough to force a rapid change of angle of attack, with the following effect,
1: 10+ G immediate pull, pilot goes to sleep
2: Tailwheel uplock failed (main gear hangs in there, stronger uplocks)
3: deformation of the rear fuselage
4: rapid climb uncontrolled with a slight angle of bank still induced (he was still in a slight LH turn)
5: its a laminar flow wing, so it describes a parabolic arc, comes over the top, and due the still applied bank, comes down the other side, as lift once again increases, it starts to pull out of its dive, but not enough and hits at about a 75 degree down line.
6: He may well have woken up during this, as there would have been at most 3-4 G at the top of the arc, but by then he was probably well below the canopy rails, definately confused, and since he does not appear to come back up, maybe his seat had broken, which would mean he could not really get back up to see where he was.

I am not in any way playing NTSB here, this is merely my thoughts, and just commenting on the evidence, both written and video shown to date.
I have I never flown an unlimited on the course at Reno.
(However I have raced at Reno in the Biplane class, so I have a small insight into the various factors on the course)
This is mainly intended to expand on the trim issue a little, as some have asked.

Last edited by Moggy C; 20th September 2011 at 11:00. Reason: Small correction of typo for sense.

http://forum.keypublishing.co.uk/showpo ... tcount=149

Unfortunately new footage has alowed the news cycle to go around again, with a (in this case) sensationalist version of the events. Not so good.

Quote:

Terrifying new video shows the moment a plane slammed into a crowd of spectators has been released.

It comes as the death toll in last week's air show accident in Reno, Nevada, has risen to 10, the Las Vegas Sun reports.

The video was shot by a spectator and was shown on the NBC 'Today' show. It shows a World War II-era fighter plane crashed into a grandstand full of spectators who had come to see the National Championship Air Races and Air Show, held every September in Reno.

Many people were killed instantly and more then 70 were wounded by shrapnel wounds, with many losing limbs.

Spokeswoman Jamii Uboldi from Saint Mary's Regional Medical Centre told the media on Monday the latest seriously injured victim to die was a man, but she refused to identify him.

The audience had virtually no time to react before the plane ploughed into the stands at high speed, killing seven people outright and injuring dozens more.

The pilot of the P-51 Mustang, Jimmy Leeward, died on impact along with six spectators, and two other people died a few hours later at a nearby hospital.

Investigators are looking into a piece of plane tail that appears to have been snapped off.

They have recovered several key pieces of the plane, including the flight data recorders.

"There are a lot of photos of specific aspects of the tail," National Transportation Safety Board member Mark Rosekind told the New York Daily News. "We have found in the wreckage some parts of the tail from the accident aircraft. We have those photos."

http://au.news.yahoo.com/world/a/-/worl ... oll-rises/

Randy Haskin · **Posted:** Tue Sep 20, 2011 10:10 am

Quote:

The racers are all trimmed prior to entering the course with a large nose up trim bias, the idea being as they approach the race speeds they can relax the push, as the trim will be correct for the speeds, 400 plus, so one less item to think about, in what would be a pretty intense environment.

The problem with that, James, is that at speed an aircraft has nose DOWN trim, not nose UP. Speed increases, nose down trim increases.

If the racers were set up for "race speed trim" as they were entering the course, that would require putting back pressure on the stick to keep it in level flight, with the back pressure decreasing as speed increased...not the other way around, as indicated in this passage.

I understand the idea of a little back pressure trim to assist with the control forces while making the turns, but this, too, would be a comparatively nose down trim condition while they were forming up for the start.

For the airplane to be somewhat manageable in the straight stretches when not in a bank, it would still require a significant amount of nose down trim when compared to "neutral".

Shay · **Posted:** Tue Sep 20, 2011 10:28 am

Does anyone have pics of Galloping Ghost's cockpit interior and restraint system? I'm curious as to how Jimmy was forward in the cockpit. Wouldn't the abrupt climb have pushed the pilot back against the rear of the seat?

Thanks

Shay
____________
Semper Fortis

happymeal · **Joined:** Fri Dec 10, 2004 7:00 am **Posts:** 215

But after the abrupt pitch up, the plane went ballistic... and inverted, and Jimmy Leeward had more than certainly passed out by then, not to mention he may have had broken cervical vertebras. Bob Hannah said that when he woke up from the 10 G pitch up due to departure of the trim tab on Voodoo, he found himself bent to his laps, hands by his feet.

Django · **Posted:** Tue Sep 20, 2011 10:42 am

Shay wrote:

New unreal footage as shown on the Today Show today. It's been said before but this Video points out from the impact this could have been much worse, .....but not by much

http://www.youtube.com/watch?v=Kw2CETrj_Ao

Wow, this new video really gives a feel for just how fast it happened. Amazing.

And the guy that died saving his little boy... that one hits close to home.

lmritger · **Posted:** Tue Sep 20, 2011 10:46 am

Randy Haskin wrote:

Quote:

The racers are all trimmed prior to entering the course with a large nose up trim bias, the idea being as they approach the race speeds they can relax the push, as the trim will be correct for the speeds, 400 plus, so one less item to think about, in what would be a pretty intense environment.

The problem with that, James, is that at speed an aircraft has nose DOWN trim, not nose UP. Speed increases, nose down trim increases.

If the racers were set up for "race speed trim" as they were entering the course, that would require putting back pressure on the stick to keep it in level flight, with the back pressure decreasing as speed increased...not the other way around, as indicated in this passage.

I understand the idea of a little back pressure trim to assist with the control forces while making the turns, but this, too, would be a comparatively nose down trim condition while they were forming up for the start.

For the airplane to be somewhat manageable in the straight stretches when not in a bank, it would still require a significant amount of nose down trim when compared to "neutral".

Randy, you are far more qualified than I'll ever be in high speed flight, but I do have what may be a relevant question... would the thrust line of the engine have a direct bearing on whether the airframe needs to be trimmed up or down at high speed? Many WW2 designs had their engines mounted with a very slight degree of offset thrust, and unless I'm wrong, I believe the stock P-51 Merlin has a very slight degree of downward thrust (and I certainly welcome correction on that if I'm wrong).

The tragic circumstances aside, this thread has been incredibly educational about high-speed aerodynamic forces and I hope that trend continues... there are only so many different shades of silver paint to discuss, after all.

Thanks Randy for any input you can offer on that...

Lynn

Speedy · **Posted:** Tue Sep 20, 2011 10:48 am

Shay wrote:

Does anyone have pics of Galloping Ghost's cockpit interior and restraint system? I'm curious as to how Jimmy was forward in the cockpit. Wouldn't the abrupt climb have pushed the pilot back against the rear of the seat?

Thanks

Shay
____________
Semper Fortis

The assumption you're making is that he is sitting in the seat 'normally'. I believe two factors are at work here. One, the planes are almost constantly in a left turn, which if you look at photos of the planes out at the pylons you'll see that the pilots are almost always leaning forwardand looking left--to see where they are going in relationship to the angle of bank the aircraft is at. They're not leaning back on the seat.

Second, IF (and this is an assumption based on talking with Bob Hannah after his incident in Voodoo in 1998) the inertia reel on the shoulder harnesses is not locked, based on the fact that the pilot is already leaning somewhat forward, the body is going to bend down that way when positive g's are applied to the plane.

10+ g's on a body that is already leaning forward puts his head between his knees if he's not restrained.

When I talked to Hannah about it, his exact comment was (and taking note that he admits he had not locked his inertia reel) "I sort of came too and could feel sandpaper on my hands...and realized my hands were on the floorboards. It was dark but I could hear the engine screaming, and I could feel that the stick was wedged between my helmet and right shoulder. But I couldn't physically lift my head up. I knew I had to do something, so I sort of crooked my wrist around what I thought was the throttle and pulled it off. I started to slow down and could gradually start to lift my head up again. By that time I was up at around 10,000 feet."

Keep in mind, also, that Buckwheat was several years younger and probably in significantly better shape than Jimmy was.

garbs · **Posted:** Tue Sep 20, 2011 11:42 am

Just returned from Reno last night – had no internet access there so I caught up on all 18 pages of this thread after I got home. My sincere condolences to the Leeward family and to those injured on the ground. Not surprised to find that there were many WIXers at/near the impact and am thankful that you made it through. I hope you can let go of the sights and sound of that horrible moment. My wife and I would have been in Section 3 but decided just before we left the hotel to take a trip outside the fence to Pylon 6 for the Unlimited Gold race that day. Ironic that I was standing there, much closer to their flight path, and thinking how much higher risk that spot was than the grandstands.

Only reason I am posting this is to offer a narrative to the video that was linked a few pages earlier – it must have been shot within 100 feet either direction from where I was standing. For those not familiar with the grounds, if the finish pylon is six O’clock and the racers come down the chute to enter at about 3 O’clock (flying counter-clockwise), pylon 6 is at about the 10 O’clock position, at the top of the “Valley of Speed”. Galloping Ghost had just passed with Rare Bear close behind and I was looking back to see Dreadnaught when someone said that Leeward had pulled out. When I first found the plane again it was straight-up vertical, having crossed the crowd line near the west end of the T-6 pits (I couldn’t judge this from my position – this info is from a friend who was standing under the plane’s path). I was still hoping to see a slow push over back to horizontal flight but instead GG continued over in the tightest and fastest half-loop I have ever seen a warbird do. At the top, he was wings-level inverted on a reciprocal course and at that point it was clear it would not end well.

As GG continued around, the plane began a half roll to the left (torque, P-factor, other?) and fortunately began to pull towards the show line again. The easiest way to describe the flight path (IMO) is in terms of aerobatic maneuvers; GG did most of a ½ Cuban Eight with the exit path displaced about 90 degrees to the right of the entry. This roll caused most of the impact energy to be directed away from the rest of the crowd. Cold comfort to those injured or killed I know, and I again offer my condolences.

I have talked to many who were standing in the area looking straight up, wondering where it was going to come down – most finished the conversation with a commitment to come back when and if they allow racing again. Several Unlimited Pilots I spoke with said that Jimmy would have wanted the show to go on as well. The best way to prove this (IMO) would be to hold the race again and let the spectators vote with their wallets. If people stay away in droves then RARA will have to fold up their tent and give up. We will be there if they let us come back.

Ken · **Posted:** Tue Sep 20, 2011 11:56 am

A thrust line offset is often lateral, a cant left or right but can be up or down as well. The cant is fixed but the forces on the airplane change with thrust; the resulting changes in torque/gyroscopic effect, spiral slipstream, and p-factor. Randy explained the effect of speed on pitch trim. Another reason for change in pitch trim is change of center of gravity. Wartime Mustangs had different pitch characteristics when the fuselage tank contained fuel; that's the large example. A more subtle example would be any tandem airplane pilot noting different trim settings, stick forces, or simply turning around and visually noting a slight change in elevator position when there is a rear seat passenger or change in load as compared to an empty airplane. Another reason is configuration change; extending flaps. Either way, the pilot finds a "new neutral" given the speed, configuration, and CG that day. For that reason I don't think any thrust line cant (fixed) could cause a greater effect than already provided for such as a common CG or configuration shift (dynamic).

Designers take all this into account when establishing the pitch trim range and pitch trim neutral. In general, wings provide lift and horizontal tails provide down force. The tails "negative" lift generates induced drag of its own - made greater when out of streamline. So,for efficiency, designers ideally install the horizontal tail with an angle of incidence to allow for streamlined elevators and trim in the heart of the operating envelope. Seems like this was one reason the handling of the F-86 improved so greatly when the flying horizontal tail was introduced; the tail could be positioned optimally for varying speed regimes. When we talk about the large forces involved with trimming a Reno racer nose down, that illustrates how the course speed differs greatly with the normal envelope of a stock Mustang. Without a flying tail, neutral trim will only be ideal in one speed/CG band; it will take unwanted deflection to go either really slow or really fast.

I'm on the record as being against speculation but a technical discussion is certainly fine with me whether it's on aerodynamics or paint. This thread has become too large to focus on just one thing, but I do hope that our top concern remains keeping this particularly respectful given the trauma that so many people are still going through.

Ken

Russ Blow · **Posted:** Tue Sep 20, 2011 1:05 pm

I am going to change the topic for a minute.

It is clear that several posting here were witness to this event and the carnage that followed. I have been a paramedic for more than 20 years and while I am trained to deal with emergencies and even mass casualty events I can think of few things I have faced that would have come to this level. We are trained and we expect to see what we see. In this case it was not expected and people were not prepared.

That being said I am sure many who were involved and might not have been injured are finding it may be difficult to cope with what they experienced. I would suggest if you are having these issues to read up on post traumatic stress disorder or PTSD. If you have access to a employee assistance program take advantage of it. If not ask around to see if Fire/EMS or even the race organizers are offering any critical incident stress management. If so take advantage of that.

I know in EMS we all like to think of ourselves as impervious to what we see and what we deal with day to day but the reality is that we are all human and there are just somethings we are faced with that go well beyond our coping mechanisms. There is nothing wrong with seeking help to cope with this event. Sometimes just sitting down and talking it out does worlds of good and sometimes you just need more than that.

To you guys that were thrust into this horror take care of yourselves and your buddies. And remember there is NO harm in seeking help to cope if you need it!

Dwhart24 · **Joined:** Wed Jan 19, 2011 8:29 pm **Posts:** 83

Russ Blow wrote:

I am going to change the topic for a minute.

It is clear that several posting here were witness to this event and the carnage that followed. I have been a paramedic for more than 20 years and while I am trained to deal with emergencies and even mass casualty events I can think of few things I have faced that would have come to this level. We are trained and we expect to see what we see. In this case it was not expected and people were not prepared.

That being said I am sure many who were involved and might not have been injured are finding it may be difficult to cope with what they experienced. I would suggest if you are having these issues to read up on post traumatic stress disorder or PTSD. If you have access to a employee assistance program take advantage of it. If not ask around to see if Fire/EMS or even the race organizers are offering any critical incident stress management. If so take advantage of that.

I know in EMS we all like to think of ourselves as impervious to what we see and what we deal with day to day but the reality is that we are all human and there are just somethings we are faced with that go well beyond our coping mechanisms. There is nothing wrong with seeking help to cope with this event. Sometimes just sitting down and talking it out does worlds of good and sometimes you just need more than that.

To you guys that were thrust into this horror take care of yourselves and your buddies. And remember there is NO harm in seeking help to cope if you need it!

Good advice. After watching the unedited / raw video link posted earlier in the thread, I can't image seeing it in person. It looked really gruesome.

Ztex · **Posted:** Tue Sep 20, 2011 3:17 pm

Thanks for that perspective Russ.
I know I was absolutely shocked and dumbfounded when I saw this news Friday evening. I cannot stop thinking about it and the images will not leave me....Last night I woke up in the middle of the night thinking about it....AND I am 1,500 miles away from the scene.

Thanks to all for your technical insight and accounts.
Thanks for getting the thread back on the rails.

Still praying for all affected by this event.
Zane

TonyM · **Posted:** Tue Sep 20, 2011 3:37 pm

Can someone post a photo of the Tora pilot who lost his life?

We had the Tora gang at our Great Lakes Wing CAF base a few years back.

I have a nice photo of members of our wing posing with these pilots.

TM

CoastieJohn · **Joined:** Fri Feb 11, 2011 5:37 pm **Posts:** 1380

Django wrote:

Shay wrote:

New unreal footage as shown on the Today Show today. It's been said before but this Video points out from the impact this could have been much worse, .....but not by much

http://www.youtube.com/watch?v=Kw2CETrj_Ao

Wow, this new video really gives a feel for just how fast it happened. Amazing.

And the guy that died saving his little boy... that one hits close to home.

Wow! I don't know whether to call the cameraperson a brave soul for keeping focus or crazy for not running.

k5083 · **Posted:** Tue Sep 20, 2011 4:06 pm

Since a growling stomach half an hour earlier was the only reason I wasn't in a position to get footage like that, I have asked myself what I think I'd have done. I'd like to think I'd have kept shooting. What's the point in running when you only have time for half a step? Your number's either up or it isn't at that point.

August

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