Race 21 (N5151) Mustang Info

[Randy Haskin]

Okay, experts:

I'm looking for some stories and technical details about the Bob Abrams Mustang (44-74994) that raced at Reno '65 and crashed a couple weeks later in Boulder City.

This airplane is unique in that it was the only racing Mustang ever built by Trans-Florida Aviation (Cavalier). Technical details about the airplane are sketchy, and about all I know is that it had clipped wings, a spraybar system with a tank up in the cockpit, some kind of special canopy, and a special Merlin with a modified supercharger (which was supposedly high-tech and special at the time). It also supposedly had some kind of modified control surfaces, which I am guessing might include gap seals and some fairings.

So...what've you guys got??

[Scotty G]

Re: Race 21 (N5151) Mustang Info

Randy,

I'm not sure about the mods you listed. It's very possible they were incorporated. What I do know is that the wing to fuselage fairings were removed. People have speculated this was a partial cause to the stall/spin accident that claimed Abrahms and the airframe. Hope this helps.

[AirDOGGe]

Re: Race 21 (N5151) Mustang Info

Not much on the web. MustangsMustangs text incorrectly states that it came down in Las Vegas:

http://www.mustangsmustangs.net/p-51/p51who/276.shtml

Las Vegas is also mentioned at the warbirds resource group and the warbird registry:

http://www.warbirdsresourcegroup.org/registry/p51registry/p51-4412817.html

http://www.warbirdregistry.org/p51registry/p51-4412817.html

The NTSB report doesn't say much, but verifies the Boulder City location:

http://www.ntsb.gov/ntsb/brief.asp?ev_id=73299&key=0

I can't find anything online that goes back before the crash.

[Unregistered]

Re: Race 21 (N5151) Mustang Info

Scotty,
I'm pretty sure what you meant is that the fuselage to wing intersection fairings were distinctly different than stock.
From what I know they were custom made to a theoretical optimum of 90 degrees, with a rather hard, small radius. This was thought to be a factor in Abrahms stall spin accident. However, the proper handling of the approach wouldn't have included getting close to stalling the airplane at the altitude in which the sequence of photos I've seen have indicated.
The idea of the airplane was to go fastest out of all the racers, and it showed some interesting and well reasoned mods.

Randy,
Sounds about right. Details will be sketchy I'm sure as the principals are all gone, except Mr. Lindsay's son. Maybe he has some records?
(I knew a good friend of Bob Abrahms when I was on at TWA. He was glad to get some info I provided to him as the last he saw of Bob was when the airplane was being shipped to Florida from New York. He knew nothing of the details of the mods).

Chris...

[Pylon1_Mark]

Re: Race 21 (N5151) Mustang Info

The bright red, Race #21 N5151 F-6K Mustang of Bob Abrams had wings clipped 2 1/2 feet on each end - capped off on each end with squared-off tips (some concern was expressed about the wing tip design and the rather small ailerons). It had tight control surface fairings with no gap seals, a highly modified late model Roll Royce V-1650-9 Merlin, a water spray-bar system, and as Scotty said - Bob had removed the wing fillets/fairings (another questionable design modification). The three photos of the racer that I'm looking at make it appear unlikely that the canopy was modified - but I cannot find any supporting documentation that states it was not.

Bob had difficulty passing the pilot quals at Reno, but after practicing every day during the qualification rounds early in the morning and again, late in the afternoon after everyone else was done flying - he made the cut - qualifying in last place at a speed of 304.76MPH. In Heat #1 on Sept. 10th, he pulled out of the race on lap #6 due to an electrical problem. Bob didn't fair much better on the next day, in Heat #2 - where although he did finish in 2nd place at a speed of 357.14MPH - he did so much damage to his engine he was out for the remainder of the event. At the 1965 Las Vegas International Air Races (held in Boulder City Nevada Airport) he qualified 5th in a field of 11 aircraft at 368.27MPH - besting the efforts of Mira Slovak, Ed Weiner, Dick Kestle, Walt Ohirich, Ben Hall & Clay Lacy. Bob did OK in Heat 1-A finishing 5th at 319.97MPH - but during Heat 2-A on Sept 25th he had to pull out during lap #2 with an overheating engine. During the emergency landing attempt he crashed fatally while turning too tightly onto final, stalled and snap-rolled into the ground.

[Randy Haskin]

Re: Race 21 (N5151) Mustang Info

Thanks, guys.

Yes, the crash was in Boulder City, but the event was called the "Las Vegas Air Races", so I think that's where the discrepancy on the location comes from.

Chris - The info I do have comes via Bob Lindsay, so I've all ready explored that avenue. He's been extremely helpful, but having been a teenager while the airplane was being built he only recalls things to a certain detail level!

Mark - Good info, but a correction to your statement that the airplane was an F-6K. Abrams airplane, 44-74994 (N5151), was a P-51, and is often confused with 44-12817 (N5151T) which is the F-6K.

All - Despite what has been printed many times about the engine in this airplane, Bob Lindsay said that the engine was a RR Merlin 500 with the modified supercharger. Do any Merlin experts know the difference between a -9 and a 500?

During the course of research for my book on Cavalier, I've run across numerous "facts" that have been printed and re-printed by several authors, only to find out that they're all incorrect (note earlier discussion about the location of the crash and the aircraft type). So, I would not be surprised if the reporting of the engine type was incorrect, too.

Thanks guys...interested to hear what else you guys dig up. (nobody's going to talk about the dysentery medication?? )

[Randy Haskin]

Re: Race 21 (N5151) Mustang Info

People have speculated this was a partial cause to the stall/spin accident that claimed Abrahms and the airframe.

I'm no aerodynamicist, but I can't figure out why this lack of wing-to-fuselage fairings is batted around in discussions as a contributing factor.

The scenario, as I understand it, was that Abrams overshot his base-to-final turn and, in pulling harder to correct back to runway centerline, stalled the airplane.

First off, this type of accident isn't some weird freak situation that requires the airplane to be aerodynamically different to occur -- final turn stall/spin incidents are a constant danger, and numerous crashes have occurred in that exact same flight regime. Every military airplane I've flown has had special attention paid during training to avoiding the urge to pull back to centerline if you overshoot final. Why? Because if you try it, you'll put the airplane into an accelerated stall and crash. So, when I read a narrative on the Abrams crash, there was absolutely nothing that seemed strange about it to me.

Second, maybe it's my non-engineering pea-brain at work here, but I cannot wrap my mind around how removing these fairings would increase the stall speed so much that it would have been causal in this accident. Anyone know Pete Law (Scotty?!) and maybe he can shed some light? Has anyone ever taken the root fairings off a real Mustang, gone up to altitude and seen how it affects handling?

As a final note, remember that these mods were designed and constructed by the Trans-Florida Aviation guys, and not Bob Abrams. Abrams simply provided the cash, requested an N-number, and picked up his big red airplane when it was done in August. Some people seem to imply that because his Reno flying skills may not have been on par with the rest of the pilots that this somehow meant he was cowboying it up with the airframe mods...but this isn't true.

[speeddemon]

Re: Race 21 (N5151) Mustang Info

I can't believe you didn't come to me first with this, bro..... I'm crushed.

I agree 100% with the high-speed, approach-turn-stall assessment. Nothing they don't beat into your head a million times in flight school, ya know? But when you blow the engine and everything goes to hell in a hurry, sometimes things happen.

A friend of mine knew Bob Abrahms, and told me that Bob actually WAS a pretty good stick, and had accumulated quite a bit of flight time with Air America and such. And let me tell you...he certainly wasn't the last guy who had problems passing his flight quals for racing. There's nothing wrong with going out and practicing until you get it right. Sometimes the odds just catch up to you, I guess.

[Leo]

Re: Race 21 (N5151) Mustang Info

I'm not an expert either, but I've read in several accounts that the design of the wing/fus fairings on the P-38 was critical to it's stall charictaristics, changing the violence of the break. Could this affect the mustang too?
Stall/spin accidents seem to be heavy in the Mustang history.

Leo

[Smee Again]

Re: Race 21 (N5151) Mustang Info

As far as the -9 vs. 500 series Merlin goes, the 500 is an early version of the Merlin "transport" engine, which possesses a single stage supercharger, if I remember correctly. And although it may be possible, using the 500 motor with a modified blower really makes no sense - racing in Reno with a single stage blower isn't likely to win any championships. Even in modern day air racing, the -9 blower is by far the most effective setup due to superior fuel/air charge distribution vs. the -7. However, a common modification to the -9 blower is the use of -7 blower gearing, thus requiring less HP to drive the blower. Perhaps this was the blower modification used in Abrams' racer. Based on what we know about Mustang racers of the same era, a far more likely scenario for Abrams' powerplant would be the use of a -9 case, wheelcase, blower, pan and nosecase with 500 series heads and banks.

[Scotty G]

Re: Race 21 (N5151) Mustang Info

Randy,

I owe Pete a call soon, so I'll ask him.

I also agree with your assesment of the pull harder, stall / spin regime. However, with the small education I have in aerodynamics and such, I would suspect you allow a vortice to set up and become more concentrated if you remove the smooth contour of a fairing. It might not be the reason the aircraft stalled and spun in, but it certainly didn't help.

Good posts all around. Interesting.

[Pylon1_Mark]

Re: Race 21 (N5151) Mustang Info

During the course of research for my book on Cavalier, I've run across numerous "facts" that have been printed and re-printed by several authors, only to find out that they're all incorrect.

Yeah, I faced the same problem when researching the Beguine - a few sources said that the wings were of equal length, some not. I was just surprised that when the guy who was instrumental in building the aircraft (in a taped interview) said there was 6" cut off the left wing that some still insisted that wasn't correct. Sometimes the facts are inconsequential - simply because people choose to believe what they wish to, despite the facts.

Best of luck on your book and quest for info

[speeddemon]

Re: Race 21 (N5151) Mustang Info

Yeah, I faced the same problem when researching the Beguine - a few sources said that the wings were of equal length, some not. I was just surprised that when the guy who was instrumental in building the aircraft (in a taped interview) said there was 6" cut off the left wing that some still insisted that wasn't correct. Sometimes the facts are inconsequential - simply because people choose to believe what they wish to, despite the facts.

Best of luck on your book and quest for info

Markster...the skinny on the Beguine, from Ed Horkey, the chief engineer on the project, was that the 6" difference was a complete RUMOR. In all the research I've done on the plane (and I did a ton of it back in the early '80's), the rumors varied from 6-18 inches of how much was cut off. Seems the legend grows as the story gets passed on. But the reality of it was that one wing pod was heavier than the other, which gave the flight characteristic of wanting to roll easier to the left than the right, but there was NOT a shorter wing on one side...despite the accepted belief that there was. If you take any symmetrical shot (head on, top/bottom view) and even go so far as to measure the wings, they are identical.

[Pylon1_Mark]

Re: Race 21 (N5151) Mustang Info

Markster...the skinny on the Beguine, from Ed Horkey, the chief engineer on the project, was that the 6" difference was a complete RUMOR. In all the research I've done on the plane (and I did a ton of it back in the early '80's), the rumors varied from 6-18 inches of how much was cut off. Seems the legend grows as the story gets passed on. But the reality of it was that one wing pod was heavier than the other, which gave the flight characteristic of wanting to roll easier to the left than the right, but there was NOT a shorter wing on one side...despite the accepted belief that there was. If you take any symmetrical shot (head on, top/bottom view) and even go so far as to measure the wings, they are identical.

The wing modification was done after Ed's involvement with the racer... so he knew nothing about it. The only people that knew about the modification were JD Reed, Walter Beech, and the handful of people that went to Anthony, KS who were involved in the actual modification of the right wing... Ed Horkey wasn't one of them. Don't believe me.... just watch the video.

JD Reed speaks on the Beguine

This was recorded in 1988 - and what a lot of my article was based on. If anyone would like to dispute the contents or originality of the video - then I'm more then happy to listen to them.

Post up

Edit: I should have said the right wing in my previous post - sorry for the error.

[Apteryx]

Re: Race 21 (N5151) Mustang Info

Mark-
What was the source of the video clip, anything that's still available?
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Paul