Fwd: Reno Air Race - Probable conclusion to fatal crash



Stab. I'll have to take a closer look next time I'm at the airport The camber is not much, compared to the fat stabilizer on the 701, but from what I remember it is opposite in format from the 701
Many planes have pretty well symetrical stabilizers.
I guess "lifting tail" isn't totally accurate - but a lot less of a downforce tail. Different hacks for different tracks - a faster plane gets more downwash from the wings thet forces the tail down much more at speed. A slow-flying plane like the 701 and Pegazair depends more on the reversed airfoil for the downforce. On a very fast plane like the p51 the stabilizer is almost like a knife blade or a plank - not much camber either way.
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snipped-for-privacy@snyder.on.ca wrote:
...

Yeah, well, perhaps Richard is knowledgeable about boats. :)
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On 9/30/2011 1:03 AM, Beryl wrote:

A little...
Sept 20, 2011. At 6:30 the lake was so smooth it was glassy.
At 7:00 things changed! The cold front moved through and the wind picked up from zero.zero to over 20 gusting 36(!).
I had met Jim and his family earlier, circling each other to speak. They bought Stephen's Catalina 27 and were hoping the front would bring some wind.
It did. Ob boy did it did! Wind went from nothing to half a gale in nothing flat.
Good Times crew hadn't been out in this much wind in this boat before. They had a bit of trouble getting the main down downwind. But it finally did come down ok. I was just trying to keep from running over them!
At least it wasn't a totally boring afternoon! Some spray in the face, a couple of cold shots of adrenalin, and all was right with the world again.
Not a lot of video here, my phone kept dropping clips. (I learned that it does that if I don't close them properly) But sometimes I'm just too busy to worry with buttons! This was definitely one of those occasions. I'm impressed that I got what I got. From a telephone? Really!

http://www.youtube.com/user/cavelamb?feature=mhee

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Yeah... do you? Although I have lots of hour PIC, I've never flown a full-scale pylon racer. But (just like the guy in a Holiday Inn Express commercial) I've flown model pylon racers. Real (not scale) speeds of 200+ mph. They are not "toy" airplanes, they're real airplanes made smaller. They behave to aerodynamics just like big ones (although they tend to leave less wake turbulence<G>).
We trim 'em out for max speed. Then we honk on the stick pretty hard at low speeds, just to keep the nose up. So what?
The ONLY reason these full-scale racing guys want to land for, at all, is so they can gas up and do it again! So long as the aircraft handling is survivably safe at landing and takeoff speeds, all they're concerned with is how clean they can make it at full speed.
Since one _can_ adjust one's approach speed, there need not be any compromises.
LLoyd
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You are wrong Sir. The P-51 was designed to meet the specifications set out by the British Purchasing Commission and the prototype was rolled out 102 days after contract sighing and was first flown on 26 October 1940. They were first used by the Royal Air Force and from late 1943, were used by the USAAF's Eighth Air Force to escort bombers in raids over Germany,
I can find no evidence that the Vertical fin was offset in any manner and I do know that the late model fuselages and canopies required addition of a dorsal fin to increase lateral stability.
The report I quoted was prepared by the AAF Flight Test Division at the request of the Production Section, Procurement division, to verify the supplier's figures.
The stated conclusion was that "control and handling characteristics of the P-51H are good under conditions tested with the exception of a tendency to hunt directionally at indicated speeds above 400 MPH.
(this by the way is typical of a plane with a marginal amount of vertical stabilizer)
As for 20 year olds, I know of no military airplane that performance was dummied down to meet the abilities of inexperienced pilots. Quite the opposite in fact, they are designed to meet a need specified by the Military and in quite a few cases that results in aircraft that are distinctly "Twitchy". The F-100A, for example, officially entered USAF service on 27 September 1954 with 479th Fighter Wing at George AFB, CA. By 10 November 1954, the F-100As suffered six major accidents due to flight instability, structural failures, and hydraulic system failures, prompting the Air Force to ground the entire fleet until February 1955. Does that sound like an airplane designed to be flown by novices?

The F-51 did not have a movable horizontal stab. A trim tab will generate more force as air speed increases.

Cheers,
John B.
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john B. wrote:

The Reno P-51s, at least one that AOPA Pilot magazine carried an article about, have the vertical fin re-aligned as I described. The article specifically said that the stock airplane was tamed so as not to kill new pilots, and the Reno P-51s are re-rigged for less drag and maximum speed.
I think the same article also says that the racing engines remain basically stock. They already can produce more power than their metal is capable of containing.
Do I need to find that magazine? I really don't want to search through a 4-foot tall stack of magazines.

It's an old report.

The need wasn't top speed. They were designed to perform as well at 200 mph as at 400 mph. Pilots racing them today don't care about much of that.

All horizontal stabilizers are movable! Take out rivets, cut, bend, and put it back on in a new position. Even the famous air scoop under the P-51s belly is movable. The Galloping Ghost's was moved somewhere, I can't see it in any pictures.
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Yeah, again, although he protested loudly about it, he didn't read the post he responded to.
Nobody SAID the stab was "movable", only that its incidence angle was set; set by modification, not by "articulation".
Any aircraft can have modifications. I wonder if he thinks the incidence angle of the stab (or wings, for that matter) was just accidental?
I helped a friend modify a DC3 for export (he did one about every seven months). I'm not an A&P, but I'm an aircraft "groupy" and always willing to throw in some grunt labor on an interesting project.
Before we were done, we'd changed a whole lot of how the airframe worked, including re-bracing and re-framing the starboard side of the fuse, carving a 10' wide cargo door in the side, and moving numerous components, including electrical and hydraulic systems. We didn't move the vertical or horizontal stabilizers, but it's pretty apparent how one would go about it.
I also helped another friend rebuild an SNJ (got to fly it, too! <G>). That project was almost a complete un-skin job. There was all kinds of corrosion in load-bearing structures. It took a while. And while he was at it, he made mods... <G> Any aircraft can be modified, even some of those "glass slippers" like GlassAirs or Rutans.
LLoyd
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On Sun, 25 Sep 2011 16:38:44 -0500, "Lloyd E. Sponenburgh"

And EVERY modification, unless in Unlimited experimental class, requires [aterwork up the yazoo - and on certified planes it requires a "supplimental type certificate" for EVERY modification.
If exporting to the third world, one MIGHT get away without.
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snipped-for-privacy@snyder.on.ca fired this volley in

No... even with the market, one had to STC every change, because the aircraft had to be flown "commercially" (that is, in pursuit of being sold) in US airspace.
Dick had all the approvals. The inspectors would glide by about twice a week, just give a cursory look, and sign off. Remember, Dick did this for a living, and had all the mods pre-approved. So it wasn't like doing "custom" mods.
LLoyd
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On Sun, 25 Sep 2011 16:38:44 -0500, "Lloyd E. Sponenburgh"

So what? We once manufactured and installed the entire aft fuselage on a U-10 that had been run into by a truck at Nha Trang. We removed the floor from the cargo compartment of a C-47 gunship and replaced all the supporting structure after the crew complained about the mini-guns "wiggling".
But this is not to say that we arbitrarily changed the incidence of either the wing or stabilizers.
Cheers,
John B.
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And that's not to say that they "arbitrarily" changed anything, either. But they could -- relatively easily, considering the scope of a complete re-build.
And I'll bet they did, because almost any aircraft can benefit from some tweaking. But certainly not "arbitrarily". There's a boatload of empirical data on how to make the P-51 a better racer. They've been flying them in pylon circuits for a lot of years.
LLoyd
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Not to argue but here is what I can find about the P-51's dorsal fin, which was not fitted to the earlier aircraft.
Despite these modifications, the P-51Bs and P-51Cs, and the newer P-51Ds and P-51Ks, experienced low-speed handling problems that could result in an involuntary "snap-roll" under certain conditions of air speed, angle of attack, gross weight, and center of gravity. Several crash reports tell of P-51Bs and P-51Cs crashing because horizontal stabilizers were torn off during maneuvering. As a result of these problems, a modification kit consisting of a dorsal fin was manufactured. One report stated: "Unless a dorsal fin is installed on the P-51B, P-51C and P-51D airplanes, a snap roll may result when attempting a slow roll. The horizontal stabilizer will not withstand the effects of a snap roll. To prevent recurrence, the stabilizer should be reinforced in accordance with T.O. 01-60J-18 dated 8 April 1944 and a dorsal fin should be installed. Dorsal fin kits are being made available to overseas activities"
One specification that was part of the cockpit canopy modification was " Because the new structure slid backwards on runners it could be slid open in flight. The aerial mast behind the canopy was replaced by a "whip" aerial which was mounted further aft and offset to the right."

True, but it is the report that the AAF produced at the time the P-51H was accepted by the AAF.

Actually most of the modifications of the P-51 were to improve high altitude performance or to allow better visibility. The original Allison engines were actually more powerful then the later fitted Packard-Merlin however the Packard-Merlin with their two speed supercharger were faster at altitude.

Certainly one can butcher anything but it is a bit more complicated then taking out rivets and bending. The horizontal stabilizer is a major control surface and on these airplanes a fixed structure. The cooling scoop is not movable, again it is a fixed structure. What you are referring to was, I believe, the total removal of the cooling scoop done to the Ghost as part of converting the cooling system to a totally different type - the "boil off cooling system". Cheers,
John B.
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wrote:

Correct, the British specified the Alison V-1710 ( 1475 H.P. @ 3,000 RPM) and "was first flown operationally by the Royal Air Force (RAF) as a tactical-reconnaissance aircraft and fighter-bomber".

Not correct. Both the Allison and Packard-Merlin engines were supercharged. The most powerful version of the Packard-Merlin V-1650-9 was actually of a lower horsepower (1380H.P. versus 1475H.P.) then the earlier Allison. The difference was that the Packard-Merlin had a two speed supercharger which allowed better performance at altitude then the Allison. The first airplane fitted with the Merlin engine was an RAF test craft and first flown on 30 April 1942.
Cheers,
John B.
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wrote:

I give. I've flown
Ercoupe Tri-Pacer J-3 Luscombe Stinson 108 150 Aerobat 152 172 182 207 Grumman Tiger Aztec Queen Air King Air Beech- 18 DC-3
Lived on three airports. Soloed on 16th birthday. VIP pass for CAF And have heard countless flying stories from;
WW-l Barnstorming Small home built race pilots WW-ll Korea Nam Crop dusting Fire fighting Smuggler Pilots
We use to modify aircraft including
Painting crash repair long range high loads gear conversions Speed Navigation Camera pods
& I've use to grind cranks for a FAA repair station.
Also have flown in bad weather, fogged in, running on fumes and lost (Dad was cheap and used road maps or just water tower names.), aerobatics (day & night), flown under power lines, engine failure, and even snuck-in to an international airport at night without radio, instrument panel lights, or navigation lights (electrical failure and runway light down at our airport (typical).).
So, most if not all planes have a metal tab on each control surface that is bent so that the controls are neutral in flight. Some aircraft have adjustable trim controls in the cockpit which are adjusted for load, prop settings, RPM, navigation, weather, ect. The most I've ever seen is in a Staggerwing Beech. The trim is used mainly to get the plane to fly straight without any input from the controls, because all airplanes pull to some direction due to imperfections in construction or modifications down to as simple as new antennas to unlimited race plane mods.
I tryed to back out of this conversation cause I just don't know the P-51 and the over powering of one. Matter of fact I don't think I've ever seen the cockpit of one, I'm guessing it has a yoke instead of a stick. Anyhow, you quote that the plane was (jacked-up my terminology) trimmed, one permanent and one adjustable for the elevator and the adjustable took a flight.
In my experience all simi-stable aircraft should fly straight and not trimmed so hard that it causes black-out G-forces if a tab takes off. Also, this type of plane took 20mm hits in the war. I would venture a speculation (after your info.) that all the planes in the race are trimmed hard so that during the straightaways the stick is pushed hard forward, because it is easier to push against the back of the seat than to stand on the rudder and pull back around the pylons and thus the plane would be in the controls neutral position in the turns.
I'm also not sure if the unstableness of loosing that part would exponentially increase or it got jerked out of his hands or the cable for that trim could have broke in the cockpit and the cable got violently stripped through the fuselage and by all the cables for the control surfaces...
BTW, prop wash from these planes must be very violent.
SW
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On 9/24/2011 8:40 AM, Sunworshipper wrote:

You know your stuff alright.
But, for a moment, imagine what it would be like to fly any airplane without a trim system.
The aircraft will be naturally trimmed to fly hands-off at ONE GIVEN SPEED.
So at any other speed, the pilot has to provide the control force to maintain attitude (and thus airspeed)
Assuming we are trimmed for cruise - approach and landing are going to be "interesting"...
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wrote:

You are overlooking the fact that as speed changes then so does lift and drag and torque, in a propeller driven airplane, and center of gravity changes dependent on load. There has to be some mechanism to balance these forces.
These changes are rather large - air pressure at, say 500 mph, is approximately 25 times that at 100 MPH. A control surface that is adequate at take off( say 100 MPH) would be 25 times too large at 500 MPH. Or to put it another way, a control surface that was adequate at 500 MPH would be 25 times too large at 100 MPH.
Cheers,
John B.
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wrote:

Correction: "Or to put it another way, a control surface that was adequate at 500 MPH would be 25 times too SMALL at 100 MPH. Cheers,
John B.
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On 9/22/2011 7:17 AM, john B. wrote:

Better :)
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wrote:

The plane hit 15 G's before impact. That makes the pilot's head weigh something in excess of 400 lbs, which could very well have instantly fractured the pilot's neck.
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