unpiloted landing in a field

Astro14

$100 Site Donor
Staff member
Messages
13,238
Location
Virginia Beach
The F-106 was a tough airplane...and the airplane kept creeping along in the field after it landed...the heat from the engine melted the snow underneath, and it slid slowly forward with the engine pushing and the heat melting the snow...bad enough to have an airplane crash into your field...but one that keeps moving afterwards??...yikes!
 
Messages
1,510
Location
Ca USA
Cool story... a delta has the advantage of Vortex lift during high angles of AOA... it doesn't stall like a traditional wing... rather it will mush level all the way to the ground... On a traditional aircraft's wing a swirling vortex is formed only at the wing tips. On a delta wing at low speeds, such a vortex is formed nearly enough along the entire wing surface and produces most of the lift in those conditions. Have you ever noticed Concorde's high angle of attack at low speeds??? that is possible because the amount of vortex lift that is generated by the wing increases significantly, and this is fundamental for Concorde to be able to fly at slow speeds during take off and landing... so much so the nose drops to aid the pilots forward visibility...
 

Astro14

$100 Site Donor
Staff member
Messages
13,238
Location
Virginia Beach
A low aspect delta wing also has a very flat coefficient of lift curve. But at that high AOA, the induced drag becomes fierce...part of why AF 4590 crashed only a few miles from takeoff...even two engines in full "reheat" couldn't overcome the drag of the delta wing at high AOA.
 
Messages
1,510
Location
Ca USA
Originally Posted By: Astro14
A low aspect delta wing also has a very flat coefficient of lift curve. But at that high AOA, the induced drag becomes fierce...part of why AF 4590 crashed only a few miles from takeoff...even two engines in full "reheat" couldn't overcome the drag of the delta wing at high AOA.
True at high AOA induced drag is high but the probability of a stall spin at low speeds is low...
 
Messages
1,066
Location
Minnesota
yup=forgot about that. When I was a B-52 weenie in SAC, we had a tennant F-106 squadron assigned and heard about this. I'm not sure at the time many believed the story tho!
 

Astro14

$100 Site Donor
Staff member
Messages
13,238
Location
Virginia Beach
Originally Posted By: BusyLittleShop
Originally Posted By: Astro14
A low aspect delta wing also has a very flat coefficient of lift curve. But at that high AOA, the induced drag becomes fierce...part of why AF 4590 crashed only a few miles from takeoff...even two engines in full "reheat" couldn't overcome the drag of the delta wing at high AOA.
True at high AOA induced drag is high but the probability of a stall spin at low speeds is low...
The point is: you can get to an AOA where the drag exceeds available power. Sure, no stall/spin...but the airplane is going to come down...and below a certain altitude, it will hit the ground before it can recover. I've seen this in ACM with true delta wing airplanes. Still able to maneuver, but the AOA is so high that the airplane is descending in full AB...so, the only way to start climbing again is to unload the AOA (thus descending even more) to reduce drag, gain airspeed and get back to a point on the lift curve where there is excess power again.
 
Messages
1,510
Location
Ca USA
Originally Posted By: Astro14
The point is: you can get to an AOA where the drag exceeds available power. Sure, no stall/spin...but the airplane is going to come down...and below a certain altitude, it will hit the ground before it can recover.
True... a delta may develop into a deep stall that exceeds available power all the way to the ground... but thanks to vortex lifts tenacity and equal attachment to the top of the wing (in yellow) you won't tumble and roll and dig a big hole...
 
Last edited:
Messages
3,941
Location
Ohio
Fascinating discussion on delta wing flight characteristics. I guess this is the closest automatic safety feature a fixed wing jet could have that would be analogous to autorotate on a helicopter.
 
Messages
139
Location
Arkansas
I can't argue with the theoretical flight characteristics of the delta wing, but I can tell you from personal experience that the delta wing will stall, depart, and spin. I have over 1500 hours in the F-106 and absolutely loved the machine. However, at slow speed or high AOA you had to be very careful. The aircraft would go into heavy buffet, and then in a nanosecond, one wing would stall, and the aircraft would depart. If you were lucky, the nose would end up pointed straight down, and you could recover. If you were unlucky, the aircraft would end up in a flat spin or post stall gyration and was usually not recoverable. That is what happened to this pilot. The force of the ejection seat leaving the airplane, and the resulting airflow disruption, caused the nose of the aircraft to drop and the aircraft recovered from the spin/gyration. The aircraft was trimmed for level flight, and in a one in a trillion event, reached level flight and the ground at the same time. Intentional stalls were prohibited in the Six because of the danger of losing the aircraft. I only stalled and departed the aircraft one time. It happened in a flash and I was lucky because the nose ended up straight down, and I had enough altitude to recover. Still it was a GREAT machine! It was way ahead of its time in many ways.
 
Messages
117
Location
Georgia
Wow is an understatement. I had never heard of this before. Thanks for posting. Martin Caidin had two "tales" of a B-17 and a P-38 landing with no crew/dead pilot. After I read those, I treated his work as fiction.
 
Messages
1,510
Location
Ca USA
Wingman... I salute your piloting skills in recovering from the stall and departure... your hands on pilot's perspective is what was missing from the thread... most of us aren't so lucky to have piloted a military fighter jet let alone a Convair 106... you could go on and on and I'm sure we would all be attentive listeners... like what Angle of Attack did you experience the "heavy buffet"??? and please elaborate why it was "ahead of its time"???
 
Last edited:
Messages
5,651
Location
Iowa
Originally Posted By: BusyLittleShop
Wingman... I salute your piloting skills in recovering from the stall and departure... your hands on pilot's perspective is what was missing from the thread... most of us aren't so lucky to have piloted a military fighter jet let alone a Convair 106... you could go on and on and I'm sure we would all be attentive listeners... like what Angle of Attack did you experience the "heavy buffet"??? and please elaborate why it was "ahead of its time"???
That makes two of us. If you have the time and inclination, please do!
 
Messages
139
Location
Arkansas
The Six was built in the late 50s. It did not have an AOA gauge. The plane had to be flown by "feel" at slow speeds/high AOA. Leaning to fly this machine by "feel", helped me greatly in the F-4. The F-4 did have an AOA indicator, but the lessons learned in the Six helped a lot at slow speeds/High AOA. The Six was very much ahead of its time. First, the airframe: It was a very "clean" design, even with the two 360 gallon external tanks. Most other fighters were a lot less clean. As those other fighters approached Mach 1, parts of the airplanes would start to go transonic at around .9 Mach and the speed would stagnate. That means that you would have to select afterburner (greatly reducing range) to get to, and then through Mach 1. The Six would go all the way to .99 Mach before having to select afterburner. That means the jet would have a 50 to 75 knot speed advantage without afterburner. Before the jet was retired, several speed records were set over the US by the Six because, it was the fastest jet in the world subsonic. Over the US you were not allowed to fly supersonic. Also, many of the modern jets are advertised as Mach 2 capable, but in reality the engines are de-tuned to make them last longer, and the jet is not really capable of Mach 2. You could pick any Six off the line, and it would run Mach 2 (without external tanks) because it was so clean. The aircraft was also the most maneuverable jet in the inventory, at the time, until the F-15 appeared. The F-4 was no competition. Also, the weapons were carried internally like the F-22 and F-35. The engine: The engine was the J-75. It was the same engine used in the F-105 and the U-2 (without afterburner). It was the largest turbojet ever built, and was an outstanding engine in dependability as well as performance. Weapons system and avionics: The radar, with its anti-ecm features was the not surpassed until the F-15 appeared. It also had an infared search and track system that has only be used on the F-14 (I think). Other fighters have heat seaking missiles, but no IR search capability. In the cockpit, the jet had "tape" instruments instead of round gauges (kind of like a modern airliner). It really made instrument flying a lot easier. It also possessed a "data link" system, so radar controllers on the ground could tell you were the target was, and tell you headings and altitudes to fly to get to the target, without any voice commands. The weakness of the Six was that is was classified as an "interceptor". All the money and modifications went to the F-4 (Vietnam war). It gradually became irrelevant because the interceptor mission went away, and its weapons became obsolete because they were never modified. Overall, an absolutely outstanding plane that was never allowed to reach its true potential.
 
Messages
1,510
Location
Ca USA
Thanks wingman... The F106 was a clean design thanks to Aviation Pioneer Richard Whitcomb and his proposed "Area Rule" which greatly reduced drag during transonic speeds... technically speaking before the F106 Delta Dart there was the YF102 Delta Dagger... Designed as 1.5 Mach Interceptor this new and hopeful prototype had initially proved to be a big disappointment... On it's maiden flight in 1953 test pilot Dick Johnson was barely able to exceed Mach 1 only in a steep dive... Transonic drag had exceeded the 14,500 pounds of available thrust of the Pratt & Whitney J57... The Delta Dagger was really the Delta Dragger... enter Richard Whitcomb... he was but one of the young NACA engineers assign to probe the mysteries of drag approaching Mach 1... he began poring over the photos of the wind tunnel models... he alone discovered faint shock waves were forming behind the wings and this accounted for the unexpected drag... he arrived at the Area Rule which shrunk this critical fuselage junction and gave the F106 its unique coke bottle shape... Following young Richards new "Area Rule" recommendations Convair engineers redesigned the YF102... On Dec. 21 1954 Johnson took the coke bottle shape Delta Dagger up and this time it "slipped easily past the sound barrier and kept right on flying" With the validity of "Area Rule" and "Vortex Lift" established Convair designed the F106 Delta Dart NACA/NASA Langley engineer Richard T. Whitcomb was awarded the 1954 Collier Trophy for his development of the "area rule, " an innovation that revolutionized the design of virtually every transonic and supersonic aircraft ever built. Here Whitcomb inspects a research model in the 8-Foot Transonic Tunnel at Langley. At a glance the difference of the straight and coke bottle shape fuselages
 
Last edited:
Top