From: jfb@ihlpl.att.com (Joseph F Baugher)
Newsgroups: sci.military
Subject: Re: Escorts  (Was: Re: In-flight refueling in WWII)
Summary: McDonnell XF-85 Goblin parasite fighter
Date: 29 Sep 92 12:59:38 GMT
Organization: AT&T Bell Laboratories -  Naperville, Illinois


From Joseph F Baugher <jfb@ihlpl.att.com>

In article <Buq505.J4H@lawday.DaytonOH.NCR.COM>, fist@iscp.Bellcore.COM (Richard Pierson) writes:
> 
> From fist@iscp.Bellcore.COM (Richard Pierson)
> 
> The Air Force developed an escort fighter called "The Gremlin"
> it was carried in the bombbay of a B36 and looked like a
> shortned/bent winged/bob tailed f-86. It would be dropped out
> and do an air start, provide fighter cover and then be recovered
> by its mother bomber using a BIG ring mounted behind the cockpit.
> {Reminds me of our water pickups off coranado}
> Of course it would be interesting to see who got recoverd in
> the event a few bombers got shot down kinda like musical
> chairs at 40,000 ft. There is one at Wright Patterson AFB
> in Dayton OH. Looks like something designed by the same
> guy who used to build all those "Rat-fink" models back in
> the 60's [I know, most of you haven't got a clue about that
> and I dont feel that old]


I think that you are referring to the McDonnell XF-85 Goblin 
experimental parasite fighter of the late 1940s.  

On January 29, 1944, the Army Air Forces invited the industry to 
submit concept proposals for jet fighters to escort its heavy bombers.  
Since the first jet fighters were notorious fuel hogs, they promised 
to have insufficient range to escort the long-range B-35 and B-36 
bombers then on the drawing boards.  The USAAF revised the parasite 
fighter idea of the early 1930s, and proposed that one solution to the 
problem would be for the long-range bombers to carry their protective 
fighters right along with them.  

The McDonnell Aircraft Corporation of St Louis was the only company to 
respond to the proposal.  McDonnell proposed a small fighter aircraft 
to be carried partially inside a parent B-29, B-36, or B-35 heavy 
bomber.  However, the AAF rejected this plan in January of 1945, 
concluding that the fighter would have to be carried entirely inside 
the B-35 or B-36.  

On March 19, 1945, McDonnell submitted a revised proposal, a plan for 
a tiny aircraft with an egg-shaped fuselage, a triple vertical tail, a 
tailplane with pronounced anhedral, and vertically-folding swept-back 
wings.  The engine was to be a 3000 lb. st. Westinghouse J34-WE-7 
axial-flow turbojet with a nose intake and a straight-through exhaust.  
The aircraft was to be fitted with a pressurized cockpit and an 
ejector seat.  Armament was to be four 0.50-cal machine guns in the 
forward fuselage sides.  

The USAAF liked the McDonnell proposal, and on October 9, 1945 they 
ordered two prototypes (plus one static test article) under the 
designation XP-85.  The AAF specified that the XP-85 be specifically 
tailored for carriage inside the B-36.  As a parallel development, the 
USAAF specified that the 24th and subsequent B-36s to be accepted by 
the service would be capable of carrying one P-85 plus the bomb load.  
Some B-36s would be modified so that they could carry THREE fighters 
and no bomb load.  

Conditional upon the results of flight trials with the XP-85, the AAF 
had intended to order an initial batch of 30 production examples, but 
before the completion of the first prototype this plan was shelved in 
favor of a more cautious approach in which only the two experimental 
aircraft would be acquired.  

In June 1948, the XP-85 was redesignated XF-85 when the USAF replaced 
the prefix P for Pursuit by F for Fighter.  

Since the XP-85 was to be launched and recovered from a retractable 
trapeze underneath its parent bomber, no conventional landing gear was 
fitted.  A retractable hook in the fuselage in front of the cockpit.  
During recovery, the XP-85 would approach its parent bomber from 
underneath, and the hook would gently engage the trapeze.  Once 
securely attached, the aircraft would be pulled up into the belly of 
the bomber.  If an emergency landing were necessary, the aircraft was 
provided with a retractable steel skid underneath the fuselage, and 
the wingtips were protected by steel runners.  

Since no B-36 could be spared as yet for the project, a 
Bell-Atlanta-built Boeing B-29B-65-BA (Ser No 44-84111) was specially 
modified for use as the mothership in the initial testing.  
Redesignated EB-29B, it was fitted with a special launch-and-recovery 
trapeze that would be used for the first test flights of the XP-85.  

In June 1948, the XP-85 was redesignated XF-85 when the USAF replaced 
the prefix P for Pursuit by F for Fighter.  

The first prototype XF-85 (46-523) was damaged at Moffett Field, 
California during wind tunnel testing, so it was the second aircraft 
(46-524) that was used for the initial flight trials.  These began on 
August 23, 1948.  Initially, the XF-85 made captive flights suspended 
beneath the EB-29B at 20,000 feet above Muroc Dry Lake (later Edwards 
AFB).  The first free flight came on August 28.  The test pilot 
detached his XF-85 from the EB-29B and flew free for 15 minutes while 
he evaluated the handling properties of the new fighter.  However, 
when it came time to re-hook, he ran into trouble.  The XF-85 was 
caught in violent air turbulence underneath the parent aircraft.  
After ten minutes of futile attempts to hook onto the trapeze, the 
XF-85 was slammed up against the trapeze and shattered the canopy.  
Fortunately, the pilot was uninjured and he managed to make an 
emergency landing on the dry lake bed below.  

Following repairs, 46-524 made three flights on October 14 and 15 of 
1948.  Three successful recoveries were made, although each one of 
them was a rather harrowing experience for all concerned.  However, on 
the fifth flight, more trouble was encountered.  The removal of the 
temporary fairing around the base of the hook resulted in severe 
turbulence and loss of directional stability, forcing the pilot to 
make another emergency landing.  Vertical surfaces were added to the 
wingtips in an attempt to improve directional stability while flying 
in the turbulent air underneath the EB-29B.  However, this did not 
help very much, and the sixth XF-85 flight ended in yet another 
emergency landing on the lakebed.  The same fate awaited 46-523 on 
April 8, 1949, when it made its first and only flight.  

In spite of the problems encountered with recovery, the XF-85 handled 
quite well in ordinary flight.  Its test pilot commented favorably on 
the stability, control, and spin recovery characteristics.  Estimated 
maximum speed was 648 mph at sea level and 581 mph at 35,000 feet.  
Initial climb was estimated to be 12,500 feet/min, and service ceiling 
was estimated at 48,000 feet.  I don't think that the armament of four 
0.50-cal machine guns was ever fitted.  

However, the Air Force reluctantly concluded that since the recovery 
operation was so difficult a job for experienced test pilots, it would 
be far too much of a handfull for the average squadron pilot.  In 
addition, it was projected that the performance of the XF-85 would be 
inferior to that of foreign interceptors that would soon enter 
service.  Furthermore, a budget crunch in the autumn of 1949 led to a 
severe shortage of funds for developmental projects.  Consequently, 
the Air Force terminated the XF-85 program on October 24, 1949.  

I have never found any references which state that the XP-85 ever made 
any flights from a B-36 mothership.  

Although the XF-85 Goblin was ultimately unsuccessful, it did provide 
some valuable data that was of use in the 1950s when the Republic 
RF-84F Thunderflash reconnaissance aircraft was adapted for launch and 
recovery beneath a B-36 bomber.  

XF-85 Ser No 46-523 is currently on display at the Wright-Patterson 
Air Force Base Museum.  I saw it there in May of this year.  It is 
indeed one tiny airplane! 


  McDonnell Douglas Aircraft Since 1920, Volume II, Rene J. Francillon, 
  Naval Institute Press, 1990.  

  The American Fighter, Enzo Angelucci and Peter Bowers, Orion Books, 
  1987.  

Joe Baugher       AT&T Bell Laboratories    2000 North Naperville Road 
		  Naperville, Illinois 60566-7033.   (708) 713-4548