Coupling airplanes

Vladimir S Vakhistrov

He is the pioneer (to my knowledge) of the parasite-concept. His first experiment dates from 1930. He launched a aerial target from a R-1 biplane. This test resulted in the idea to launch manned fighters in the air to make their range longer.
The first test with manned fighters was done by placing two modified (removed lower wing from this biplane) I-4 fighters on top of the wing of a TB-1 (ANT-4). The modification of the biplanes was done because they feared that the lower wing would be in the turbulent air from the propeller of the "Aviamatka" (=mother aircraft). First flight of this combination was on 31 December 1931.
The combination was called "Samolyot zveno" (= aircraft nest). Vakhistrov and all the pilots received a Red Star Order for this successful test. Further development of the system lead to a combination of 6 airplanes. The mother aircraft, two aircraft on top of the wing, two aircraft below the wing and one aircraft under the fuselage. This last aircraft hooked up when the rest was in the air.
I hear you think: "Those combinations are pure circus acts, they have no operational potential." Well, you are wrong. The Russians used these combinations on 16 missions. The first attack was made on a refinery in Romania on 1 August 1941.

Incredible, isn't it. The "Samolyot zveno" of Vladimir S Vakhistrov

Click picture to get larger file.

Mounting the airplanes on top was not so easy. Large ramps were used.

USS Acron & USS Macon

I got this remark from Frédéric Grosshans: "I don't know if you consider airship-born planes as parasites. If you do, your parasite page is missing the only aerial aircraft carriers, the USS Akron and its sistership the USS Macon, built by the US Navy in 1931 and 1933. Each airship carried 5 "sparrow hawk" planes, which could take off and "land" from the ship during flight.

UK airship with Sopwith Camel

I think the USA edition was easier for the pilot. Here he had to be a real daredevil to get in the airplane.

Short Mayo Composite

Major R H Mayo had a idea to give a airplane a longer range. He patented the idea and got official support. A prototype would be build by Short.  In those years flying boats were the usual airplanes for longer trips. These surely used much fuel for take-off. The idea of Mayo was to combine two airplanes. The upper component would be a aided into the air by a larger more powerful airplane. The upper component would save the fuel that normally would be used for take-off.
The lower component was a Short Empire conversion. Its engines were placed further away from the fuselage. This would allow the upper component more place between the props when disconnecting.  And the hull was wider to carry the extra weight on the water. On February 6 1938 the "composite", as it was called, took off and separated. On October 6 1938 it make a looong flight. The upper component had no payload and was filled to the neck with fuel. After 42 hours it had set a new distance record of 9 619 km (5 977 mi). According to my source (Air Enthousiast November/December 1995 No. 60) this record in this class still stands.

The Short Mayo composite before take-off

Short Mayo Composite

Upper component named "Mercury"
Power     4 x 276 kW (370 hp) at 3 650 rpm at 2 057 m (6 750 ft)
Fuel tank     5 455 liter (1 200 Imp gallon)
Top speed     341 km/h (212 mph)
Cruising speed     289 km/h (180 mph)
Climb speed     304 m/min (1 000 ft/min)
Endurance     21,5 hours at cruising speed
Range     6 115 km (3800 mi)
"Lift-off" weight     9 434 kg (20 800 lb)
Tare weight     4 610 kg (10 163 lb)
Span     22,2 m (73 ft)
Length     15,2 m (50 ft 11 in)
Height     6,1 m (20 ft 3 in)
Wing area     56,7 m2 (611 sq ft)

Lower component named "Maia"
Modified Short Empire S.21
Power     4 x 686 kW (920 hp)

DFS 230 combinations

The military glider DFS 230, which was used during the beginning of WW II to land soldiers (max. trooping load: 10) behind the enemy line, was also used in a rigid combination glider-tow plane. The tow plane was mounted on top of the glider. Several combinations were tested. Three combinations are known to me (my source is a building plan for a HUMA plastic scale model of the DFS 230). A Klemm Kl 35 (twin seated, low wing monoplane, open cockpit light trainer), a Focke Wulf Fw 56 "Stösser" (single seated, open cockpit, parasol wing monoplane) and a Messerschmidt Me Bf 109 E were used as tow planes. The advantages of this combination is mentioned as a extension of the range of the glider.

I guess that the combination also had less influence to bad wind conditions due to the lack of a loose cable between both.

DFS 230 Assault glider with a Focke Wulf Fw 56 on top as tow plane


Siegfried Holzbauer, a test pilot of Junkers, made in 1941 a proposal to use a combination of a fighter and a unmanned, bomb filled older bomber to throw the bomber on large targets like bridges, boats, factories, bunkers and so. At that time there was no need for such a radical method, so the idea was dropped. But when, at the end of the war, the Germans became desperate the idea was reborn (due to the successful flights with the DFS 230 combinations). The official name was "Beethoven Gerät" or Beethoven Device. Most know it under the name "Mistel" or Mistletoe.
As lower component they used a Junkers Ju 88. Messerschmidt Me 109s and Focke-Wulf Fw 190s were used as upper components. The Ju 88 got a special designed 380 pound warhead instead of the cockpit. At the second bomb bay 50 kg cement bombs were carried as ballast. The warhead could (at the used speed) penetrate 60 feet of reinforced concrete. Together that would give quite a bang.
DFS (having experience with the DFS 230 combinations) designed the support between the two components. The extra drag made the speed drop to 235 mph. This made the Mistel a easy target for enemy fighters.
Some operations were carried out. 4 attacked some boats, although all were direct hits, no ship sank. Several other operation were planned, but mostly dropped due to the continuously changing situation of territory. At the end most were used to destroy bridges to slow down the Allied and/or Russians.
They think that there were about 250 Mistels made. At first older Ju 88 were used, at the end they used Ju 88s straight from the factory!
To show the further development I quote a book named "Hitler's Luftwaffe" by Tony Woods and Bill Gunston (1977)(ISBN 0-86101-005-1):" In the closing weeks of the war other Mistel combinations included the Ju 88 G-7/Ta 152H, Ta 154/Fw 190, Ar 234/ Fi 103, Do 217K/ DFS 288 and for research Si 204/ Lippisch DM-1. There were many projects, such as the Ju 287/ Me 262 and Ar 234 C/ Arado E377 (small pilot less bomber) and the Führungsmashine (Ju 88H-4/ Fw 190 A-8) intended as a long-range pathfinder. The upper component in this case was purely an escort." I believe that the Do 217K/ DFS 288 was also for research.

To make things a bit more clear I made a short description of the mentioned airplanes.

Focke Wulf Ta 152: single engine aircraft (better known as "the longnoised Fw 190)
Focke Wulf Ta 154: twin engine multi-purpose (Germans attempt for a design similar as the British Mosquito)
Dornier Do 217K: twin engine bomber (advanced version of the "flying pencil")
DFS 288: High altitude reconnaissance aircraft (using a Walter rocket engine)
Siebel Si 204: Twin engine light transport monoplane with two vertical tails, each at the end of the horizontal tail surface.

The Arado projects mentioned in the quote were quite interesting. I found a good description in "Arado 234 Blitz" (Monogram Monarch 1) by J. Richard Smith & Eddie J. Creek (1992) (ISBN 0-914144-51-0 (264p- many pictures and drawings- colours- hardcover- one of my most favorite owned books!). Due to the slowness of the Mistels using the Ju 88, they couldn't survive long in a hostile airspace. Arado suggested to use the Arado Ar 234, a multi jet-engine high-wing bomber or reconnaissance airplane, as a quicker base. A Mistel like proposal suggested a Ar 234/ Ar E377. The Arado Ar E377 was a unmanned mid-wing airplane which could have a 2000 kg (4409 lb) hollow-charge warhead or a 1800 kg (3968 lb) bomb mounted in the nose. Two version of this Ar E377 were suggested. A unpowered one and a version which had a jet-engine under each wing. Both combinations had the Ar E377 mounted on a takeoff trolley and the Ar 234 was mounted on top of the Ar E377. There was also a proposal to used a Heinkel 162 Volksjager with the powered Ar E377. No prototypes were made. The war probably ended too soon.

Another interesting Arado project was to use the Arado 234 as a flying base for the Fieseler 103 (better known as the V-1). Three proposals for mounting the V-1 were made. One featured the use of a rigid tow bar behind the Ar 234. The second one mounted the V-1 on a takeoff trolley and the Ar 234 on top of it. The third had the V-1 mounted on top of the Ar 234. The last version made use of the conventional landing gear of the Ar 234. If you would think "Impossible", than I have to tell you that 4 tests were made using the first proposal. A unpowered V-1 was used during these tests. The fourth test ended in the destruction of the tow bar, due to the unstability of the concept. I guess that the other proposals would have had more success when tested.

The last (known to me) parasite Arado proposal was the combination of a Ar 234 and a Ar E381. The Ar E381 was a small, rocket powered fighter. The reasoning was that the best way to protect a fighter was to place armor around the engine and the pilot. For conventional airplanes this would lead to a increase of weight that would reduce the performance a bit too much. The tiny Walter rocket engine could easily be protected using a small armored tube. Due to the ground clearance of the Ar 234 , the pilot of the Ar E381 (which was hung under the Ar 234) had to be proned. In this position a pilot could also easily be protected with a armored tube. The first design had one difficulty: once hung under the Ar 234; there was no possibility that the pilot could leave the Ar E381. A second proposal had a sideway entrance. The AR E381 had a single 30mm Mk 108 cannon and 45 rounds of ammunition. This would be good for two attacks.

In "NATTER, Bachem Ba 349 und andere deutshe Kleinstraketenjäger" by Joachim Dressel in "Waffenarsenal"-serie (1989)(ISBN 3-7909-0361-2 (48p- many pictures and drawings- German text- soft cover)) I found a good description of how a mission with a Ar E381 would look like. First the combination took off and climbed to 6000m. Once disconnected, the Ar E381 could climb very fast (probably under a climb angle of 60° like a Messerschmidt Me 163) to the level of the bombers. On that level it had a offensive range (= area to make attacks on bombers) of 30 km. After the attacks the pilot cut power, glided away from the bombers and used the remaining fuel to look for a airstrip to land in a range of 120 km. Landings were made on a skid.
Dimensions of the first proposal of the Ar E381 were: length 4,95m; height 1,20m; span 5m; wing area 5 m2; weight 1200 kg.

I know that the plastic model firm DRAGON has several boxes with the Arado proposals (surely one with the He 162/ Ar E377 combination). Could someone help me to get permission to use the pictures of the boxes in this page. I will use the pictures as a link to whatever Dragon-site.
I don't have the boxes myself, so I could use a JPG-file of the pictures as well. Please, no e-mails larger than 500 kB (or my mailbox will not receive them) and a maximum width of 550 pixels. Thanks on advance.


Designers always wanted more wing area during take-off and less during flight. Such a proposal came in 1940. The origin of this idea dated from 1920, but I leave this origin research to historians. In 1940 W.R. Chown (Managing Director of F. Hills & Sons LTD, a manufacturer of light aircraft in Manchester, England) suggested to use a detachable wing during take-off. He had no official support, so he made the prototype using his own finances.
A manned scale model was made in seven weeks. It was a small low-wing airplane with a detachable upper wing.
Officials thought that throwing away the wing would cause problems, but the test made on 16 July 1941 proved that separation could be made without any problems. The upper wing gently glided to the sea and was lost (upper wing was designed as a expandable wing). The pilot of this test flight didn't even had to retrim his aircraft after separation. So stability was only not a problem.
The project never received any registration or serial number. Officially is was only known as "Experimental Aeroplane N°133" in the wartime series. The nickname was "Bi-Mono"

I know that this not a parasite, but I use the Bi-Mono as a introduction to the next design.

Bi-Mono of F. Hills & Sons LTD

I got this remark from Eirk Bakker: "I believe the Hawker Hurricane was tested with such a bi-mono setup !!" I know it is true, because I have a picture of it in one of my books. I didn't mention it before because it is tottally similar to the Bi-mono project.

PB 37 Slipwing

Noël Pemberton Billing (founder of Supermarine Aviation Company) was a man with many ideas, some were very unusual. One of them was the manned slipwing.
It all started with a project called PB 37. It would have become his proof of concept. The upper component was a lightly loaded (= not much wing loading) slipwing as used in the Bi-Mono. But here the slipwing was manned. The slipwing was a all wooden powered (40 hp air cooled) glider with a crucifix tail, which returned to the airfield to be re-used after separation. The lower component had a high wing loading due to a wing area that was half of that of the glider (12,5 m2 (135 sq. ft.)). Together they had a wing loading that would allow a normal take-off. Once in the air the glider disconnected and returned to the airfield. The lower component (now having a higher wing loading) continued with a now higher cruising speed due to the reduction of wing area.
Looking at the picture of the Bi-Mono, I believe it had the same wing area relation between upper and lower wing. The Bi-Mono surely is related to the PB 37. I don't know who had the idea first, but I am sure that Billings and Hills knew each other (the prototype of the PB 37 was constructed in the factory of F. Hills & Sons).
Billing designed the PB 37 as a small dive bomber. Billing states that the PB 37 could carry twice the load for twice the range on little more than a third of the power.
The production of both components began. After just 5 weeks the glider was ready. 11 weeks later the more complex lower component was nearly finished. The frame was made, but still uncovered. The central placed 290 hp engine was installed, but the fast speed driveshafts to the props and the two low speed pusher props were still missing. Here the construction ended, probably due the the end of Billing's finances (he financed the project himself). Billing never got official financial support for the PB 37. The project never flew. Billing made other proposals (even one for a huge flying boat using the same concept), but none came further than the drawingboard.

Personal impression of the PB 37 Slipwing. For reasons of clear vision to both models I separated the airplanes.

There is one thing that is not clear to me. Under the lower compartment there is a round waterdrop shaped thing. It could be that Billing wanted to show a dummy bomb in the prototype. Or it could also be a fuel tank. Looking at the position of the thing (under the CG (center of gravity)) I am sure that that thing has a variable weight (if bomb from full load to bomb gone, if fuel tank from filled to empty). Is there somebody that has the correct data in this thing?

Hills Hurricane

There was another Hills & Sons project with detachable wings. A Hurricane was outfitted with a upper wing filled with fuel. The wing had the same dimensions as the original Hurricane wing. Once empty the wing was detached and lost. They extended the range of the Hurricane this way. A small production of 40 was made.

He 111 / Fi 103 ("V1")

Although I did know about this combination, I totally forgot it while making this page. Jim Cumber ( did sent me this reminder: "Fi 103 parasite...quite a few of the V-1s were also launched from the He 111 against England, particularly after the regular launch sites on the French coast were lost after D-Day. As I recall, however, the V-1 / He 111 combo simply carried the V-1 in the He 111 bomb bay and launched it like the B-29 drop-launched the X-1 in the post-war test program."

McDonnell XF-85 Goblin

With the development of the XB-36 (unofficially named "Peacemaker") there came a large bomber, which had a loooong range and a heavy defensive armament. But they wanted more defensive for their huge B-36 fleet. They wanted fighter cover for their fleet. It seems like a perfect idea ... if they had fighters who could follow the bomber during their loooong missions. But their were no such fighters. Many thought about a possible solution. The solution could be found in the bomb bay of the huge bomber. The idea rose to make a tiny fighter that fits in the bomb bay and could be dropped whenever the bomber needed cover. Retrieval would be done by a advanced hook-up system. The requirements for this new fighter were:

  1. Gross weight not above 6 000 lb.
  2. Armament of four .50 caliber machine guns.
  3. Maximum speed  600 mph
  4. Service ceiling 40 000 ft
  5. Mission time of 1 hour (engine start to engine stop)
  6. Single place, single engine configuration
  7. It had to fit in the bomb bay of the B-36

Mc Donnell XF-85 Goblin (hihi, this is the first picture where I can draw the pilots head)

Only Mc Donnell Aircraft Company (now McDonnell Douglas Corporation) entered a proposal. Their design, the XF-85 Goblin, was at first a bit to large and to heavy, but was later approved. The airplane looked like a engine nacelle with a pilot sitting on the engine. It soon had the unofficial name "Bumble Bee" due to its fat, short shape. It had 6 tail surfaces (3 on top, 3 below), no landing gear and a hook-up system in front of the pilot. The combination was made on the ground. The aircraft was placed in a pit and then hooked up and pulled up. Since there was no B-36 available to make the test, they transformed a B-29 to carry the hook-up system.

Several flight tests were made. But some retrievals did not work as planned and did lead to belly landings. Luckily the design had a heavy plate for belly landings. In the book "YEAGER" by General Chuck Yeager & Leo Janos ( ISBN 0-09-947040-3 (paperback- 448 p- 21 pics))  Yeager (who flew chase on these test missions) says that the project was lost due to bad piloting of a civilian test pilot. "They couldn't fly in formation, they had no background or training". In the book "To Fly and Fight" (memoirs of a triple ace) by Col. Clarence E. "Bud" Anderson & Joseph P. Hamelin ( ISBN 0-553-29240-4 (paperback- 353p- some drawings of mentioned airplanes)) Anderson says that the Goblin was unstable.
The project was cancelled after only two hours of test flying. Yeager says: "It was a shame to see a good program and good equipment ruined by bad piloting."

You can see the Goblin, according to my resources ("Great aircraft collections of the world" by Bob Ogden (1991)(ISBN 1-85627-012-2 (hardcover- 200p- plenty pics)), in the Strategic Air Command Museum in Belleville, Nebraska. That is 16 km (10 miles) south of Omaha.

McDonnell XF-85 Goblin
Wingspan     6,44 m (21 ft., 1.5 in.)
Wing area     8,36 m2 (90 sq. ft.)
Length     4,53 m (14 ft., 10.5 in.)
Height     2,51 m (8 ft., 3 in.)
Empty weight     1705 kg (3,740 lb)
Gross weight     2553 kg (5,600 lb)
Maximum speed     966 km/h (600 mph) (estimated)
Cruising speed     684 km/h (425 mph) (estimated)
Climb rate     914 m/m (3,000 fpm) (estimated)
Range     805 km (500 mi.)
Armament     Four .50 cal. machine guns
Powerplant     1x Westinghouse J34-WE-22 (model 24C-4B) nonafterburning 1368 kg (3,000 lb) (13420 Newton) thrust turbojet
Production     2 prototypes


I got this from Kent R. Brockmann: "The current location of the display aircraft is about 25 miles west of Omaha: Strategic Air and Space Museum, 28210 West Park Highway Ashland, Nebraska 68003 USA

Website: "


I did mention here that I was collecting data about this item. I got this reaction by Jim Cumber ( "This was a "FIghter CONveyor" configuration somewhat similar and nearly contemporaneous to the XF-85 "Goblin" which you already have posted on your site. The concept was much simpler. Take a Republic RF-84F "Thunderstreak" and modify it to be dropped from a B-36 "Peacemaker" strategic bomber. The modified RF-84F was redesignated RF-84K. According to the 1971 version of "Military Aircraft of the World", page 112, of the 718 RF-84F produced, some 25 were modified to RF-84K standard for this project. The B-36 carrier aircraft also required bomb bay modifications for FICON: bay doors removed and "cut outs" in the sides of the bay created to fit the "Thunderflash" wings. could not retract its landing gear until the smaller plane (the wings of which were in the way) was dropped; the original idea was for the B-36 to take off and fold its landing gear, then the RF-84K would take off and use a "trapeze" hook-up device which pulled the smaller plane into the bay, similar to the XF-85 "Goblin" system. Then the B-36 would do most of the long range flying. The original idea was to fly the RF-84K out on a round trip of up to 2,000 miles, taking pictures along the way, and then recover it into the bomber using the same "trapeze" arrangement, however, they ran into the same serious slipstream and control problems which doomed the "Goblin" concept. Finally, as I understand it, they had to settle for ferrying the RF-84K (with the B-36 landing gear hanging out) no more than about 2,000 miles (the RF-84K's maximum unrefueled range) from its recovery base on the periphery of enemy territory and then let it streak for home across the target landmass, while the B-36 finally tucked its landing gear away and went about its business." Later he did a web search for me on this item. One of the sites has a good page on this item

Vogt's MX-1016

Dr. Richard Vogt, a German airplane designer know for his unusual designs (see asymmetric airplanes), was brought to America at the end of the war. He had a theory to use free floating panels to make the wingspan longer. The resulting extra lift would result in more range with the same fuel. This idea caught attention. Anderson was involved in this program. In his book (mentioned above) he writes a excellent part on this subject.
The project was called MX-1016. The first test were made with a C-47, the military version of the twin-engine airliner DC-3, and a Culver Q-14, the military version of the Culver Cadet. The Q-14 is a small, light, single-engine,low-winged, prop-driven airplane. The tests were made with a simple coupling system of a ring on one side and a lance-and-ball on the other side. After some practice couplings were made in the air. The first were a bit troublesome, but after some practice Anderson could make a coupling in five to thirty seconds. Once coupled the ailerons were useless. They found out that lining up the airplanes could be done by using the elevators. Anderson found a easy reference to line up. He used the slip-skid indicator (better known as the "ball"). He once even pulled on his parka while he was coupled. The pilot of the C-47 saw this and thought to scare Anderson by wiggling his wings. Anderson kept his eye on the ball and nicely moved along with the wiggling wing.
Many had doubts about the stability of this combination in bad wind conditions. Tests came sooner than expected. A invited photographer, sitting in a B-29, wanted to take some pictures from the front. The combination came into the prop-wash of the B-29. It became a hell of a ride, but all came out nicely. Stability was proven.
The next phase in the tests were B-29 / F-84 combinations. Here they had new problems. The wing of the B-29 did flex more than the rigid wing of the C-47. The F-84 fighter had to stay in phase with the up and down movement of the wing. After 137 couplings, using the same ring and lance-and-ball coupling as the first tests, the wingtips were provided with the necessary coupling devices to gather data to test the theory of Vogt. The former couplings proved that the concept of coupling could be done, but the air has free play between the wingtips. Vogt's theory needed wind tight connections. The test made by coupling two fighters to the bomber with the new coupling device showed that Vogt's idea was somehow right. Due to the not so excellent wind tightness of the couplings there was no gain in range, but ... two fighters had a free ride. So things did look good for the moment.
The first couplings and line-up were still done without the use of any electronic devise. But there was need for a autopilot to make things a bit easier for the fighter pilots. And here started the troubles. Electronics needs to be informed of the wanted reaction time and force. The pilots said to the technicians that they had to use the stick very gently, because some elevator deflection resulted into a heavy reaction in line-up. The first test with the autopilot went alright till the test pilot hit the button of the autopilot. The reaction of the autopilot was too hard. The fighter rotated around his wingtip. The explosive bolts, which worked when the angle between the fighter and bomber became too large, didn't had the time to react. All happened so fast. The fighter smashed into the bombers wing, destroying the bombers wing. The combination spiraled to earth. The crew of the bomber used during this flight a pressurized cabin. Normally the cabin was unpressurized, because in need it is hard to open the doors to jump. But the trust in the concept was so high that moment, that the crew used a pressurized cabin. All crew members (5+1) were lost. Anderson did lose a dear friend.

To me, a amateur, the concept was not worthless. The accident was due to ONE bad instrument, not due to the concept. Many test projects of unusual designs ended this way. Pity, critics always give the concept the blame. The Bachem Natter, a German experimental VTOL fighter, ended the same fate due to a cockpit cover that was badly glued and came loose during take-off. Another good concept that was lost.



I was surprized when I found in my books another tip coupling parasite. It is a combination of a B-36 bomber with F-84 fighters. I thought: "Hey, F-84 fighters. I have seen these before as parasites." Did the airforce restart the theory of Vogt? Or did the writer of Andersons book mistype the name of the used bomber? I don't think it is a typing mistake, because the project is labeled as "Tom-Tom" and not as MX-1016. I didn't find a as lively written text about this project as I did of the MX-1016-project. My resource, Air Enthousiast november 1990 edition, just states that the first succesful tests were done in 1953 and that the idea was quickly shelved after a F-84 tore loose of the B-36 due to the up-and-down movement of the bombers wing.

The site mentioned above (see FICON) also has a good page on this item.

Space Shuttle

I guess that most will have heard or maybe seen the next combination. It was a combination of a Space Shuttle (I think it was the Enterprise) and a Boeing 747 as mother airplane. They made a world wide tour to promote the Space Shuttle. I saw it over Brussels. It was a nice sight and it really caught attention.

I got this remark by Jim Cumber ( "The modified 747 / Space Shuttle "parasite" arrangement is still used. In those cases where weather prohibits the Shuttle from landing at Kennedy Space Center in Florida, the Shuttle lands at either Edwards Air Force Base in California or White Sands in New Mexico: it is then loaded onto the back of the modified 747 and ferried back to Florida when the weather clears, unloaded and rolled into the Shuttle Preparation Facility to be serviced for its next flight. I was living in Washington, DC when the combination you speak of was flown around the Beltway. I also saw it when I was living in Florida a few years later. Interestingly enough, I now live in Utah, a few miles from where the first few flights of the X-33 (proof-of-concept vehicle for the new "VentureStar" replacement for the Shuttle) will land and I have not yet heard how X-33 will be returned to Edwards, but it would be a "light load" for the same 747..."

SR-71 / D-21

I also found a picture of  a plastic model of parasites. But I found no proof that this combination really existed or was planned. It was a combination of a SR-71 Blackbird and a similar smaller airplane on top.

I got the following remarks.

  • From Emile "turbineman" van Essen (rough translation from original mail in Dutch): The mentioned parasite, the D-21, is a ramjet unmanned delta which would proceed where the SR-71 did stop (mach 4!). The project was cancelled due to a crash which happened during the release. You can find the D-21 in the book "World unmanned aircraft" (Jane's; ISBN 0710604017)
  • From Mike Arman: SR-71 parasite was the D-21 drone, used during Vietnam war as unmaned reconnaisance aircraft. Recently declassified. Speed was about Mach 4 - someone I know was an air traffic controller in Saigon at the time, saw a Mach 4 trace on his radar, called his superior as in "WTF is THAT?" He was ordered as follows "You don't see a thing. That is an order!"
    Some D-21s are in storage in either Arizona or California, there was an article on them on one of the flying mags.
  • From Jim Cumber ( "This most probably was the combination of the SR-71 "Blackbird" and (if my memory of the designation number serves correctly) the D-21 Drone. This was a "purpose built " combination: the idea was that the drone was carried by the SR-71 into Red China to monitor their nuclear weapons tests. The SR-71 would circle the mushroom cloud and take readings while the D-21 would fly ** through ** the highly radioactive cloud and take samples of the vaporized bomb fragments for analysis to determine what they were using as special nuclear materials to make their weapons. Then the D-21 was "remated" to the rear of the SR-71 carrier for transport to the landing point, which was either Okinawa or Guam without refueling, or the United States with several aerial refuelings across the Pacific. Several SR-71s were specially modified by Lockheed's "Skunk Works" (who built both the SR-71 and the D-21) to carry the drone. Several drones (more than there were carrier aircraft) were actually built and used.
    There has more recently (since the publication of the book) been another story circulated that several D-21 drones were also used in SR-71 penetrations over Soviet airspace, wherein the small payload bay of the D-21 was used for recon equipment to extend the reach of the manned SR-71 over more dangerous targets, where the smaller size of the drone would be less likely to attract anti-aircraft missile attention and thus prevent the loss of a very expensive aircraft and crew in what would have been a very embarrassing international incident. For what it's worth, neither the US Air Force nor the CIA (the only 2 users of the aircraft) has ever admitted to SR-71 missions over Soviet airspace.
    Both before and after the book was published, there has been additional data on the SR-71 "leaked" out which is fascinating.
    Apparently, the SR-71 flies ** substantially ** higher than the "released" 70,000+ feet altitude: try 140,000 feet or more, according to a Bob Stevens cartoon in the back of an "Air Force" magazine of a few years ago!
    Viktor Belenko, the Soviet MiG-25 pilot who flew his aircraft to Japan in 1976 to defect revealed in his book "MiG Pilot" that the MiG-25, which is capable of sustained 30,000 meters (98,425 feet) altitude, could not reach the SR-71, nor could the long-range (20+ mile) missiles fired from the MiG-25 in zoom climb reach the SR-71's cruising altitude! Nor (when the SR-71 pilots came down to "play" with the MiG-25s off Vladivostok...) could the Mach 2.8+ MiG-25 catch the SR-71 and firing the missiles from a max speed MiG-25 was also fruitless: the missiles (also capable of Mach 2.8+ all by themselves!) could ** not ** (even when given the added "boost" of Mach 2.8+ from the launching aircraft!) catch the SR-71 in a pursuit chase! Taking a MiG-25 at minimum speed and trying a head-on shot at an SR-71 couldn't cut it either: even though the MiG-25 had one of the best interceptor radars of its day (so powerful that it could instantly cook a rabbit at a kilometer range: it was a capital offense under Soviet Military Law to activate the radar, which was unjammable out to about 50 nautical miles, while the aircraft was on the ground), the SR-71 was so fast that it hit the interceptor's radar envelope, went through all 50 nautical miles of it and screamed ** past ** the MiG-25 ** too quickly for the MiG-25's radar to lock on!!! **
    How fast is the SR-71 really? For an idea, compare the aerodynamic design of the SR-71 to that of the slightly earlier X-15, which is capable of about Mach 6 or slightly better: then review Belenko's report of a MiG-25 and it's missiles trying a pursuit launch against an SR-71 and do the math!
    What is the SR-71's real maximum altitude? For many years, the apochryphal story has been out that SR-71 crews are actually awarded Astronaut Wings: which one only gets for flying above 50 nautical miles altitude...then remember Belenko's description of a zoom climb missile launch against an SR-71 and do the math again....!!
    No wonder the first airframe for the SR-71 was airframe number 2001...<;-D>   "
  • From Lars "Sez II" Mathiesen: "The D-21 (D-21A) was launced by a M-21.The M-21 was a modifyed A-12. With a launch officers instead off the CIA camera. The reason that if was called M-21/D-21 was the M was for mother and D for daughter. When in didn't work, the D-21B was used from a B-52 with a booster rocket to make the ram jet operational velocity. Once I had a interesting mail about the recovery off the D-21B drones over Vietnam. (it was blown to pieces and the film packages was recovered) It was on the nurflugel mailig list so it should be in the archives.  The SR-71 (RS-71) was an enlarged YF-12A both was USAF airplanes."

Donald Fritz did send me the following pictures. Thanks, man !!!!!!

SpaceShipOne/ White Knight

In 2003 I found out about a project of Scaled Composites. Scaled Composites is the firm founded by Burt Rutan. Burt Rutan is notorious for his unconventional designs like the Quickie, Voyager (who made the first flight around the world in one flight), Boomerang (see asymmetrical designs) and lots of others. This time they did it again. The project has two names. White Knight  and SpaceShipOne. Why? Well, it has two airplanes. One mother ship, White Knight, and a parasite, SpaceShipOne.
They hope to get the X-price. It will be won by the first orbital flight of a non-governmental supported project.

Scaled Composites' SpaceShipOne and White Knight in flight. Here they are still fixed together. Only the engines of the Knight Knight are used here. (permission to use picture from Kaye LeFebvre of Scaled Composites)

A few stills of the drop sequence video. (permission to use picture from Kaye LeFebvre of Scaled Composites)

One might ask: "Why using parasites for this kind of project?" Euh ... I am guessing here. So I hope to be right. Ok, here I go. A rocket engine is performing better at higher altitudes than at lower. So, getting it at the most performing altitude is not very efficient when you start using the engine from the ground on. And ... it uses a lot of fuel to get there. Now ... why not use a airplane that can do this for the SpaceShipOne. The White Knight carries on its own fuel the SpaceShipOne to its ideal height and releases it there. The SpaceShipOne starts its engine and still has a full tank! Off it goes ... next stop ...SPACE.
While the SpaceShipOne is climbing the White Knight can descend and maybe ... be coupled to another one and do it again. This way one can get a large crew in space at a short time using small (when compared to SpaceShuttle) airplanes. Will it be the next generation of crew changer for the manned spaceships in orbit?


I guess this is the biggest carrier of other airplanes i know of. Intended to launch rockets into space. Sadly the inventor/founder died (of old age) during its construction. Later it got a few problems with detaching of the carried load. The rocket launching was abandoned but it got further as research aircraft carrier.

Future of parasites?

I have been thinking about these parasites. I did add a page named "Sea parasite". The idea is about the combination of parasites and commercial and/or transport amphibious airplanes and maybe giants too. Go see the page in the sector "Weird designs".

I believe that parasites still have a future. Sure now that the coupling can be made "easier" with the use of automatic piloting systems. If they can make a F-117 fly, they can make this coupling!!

The SpaceShipOne shows a great advantage of parasites.
"Let another airplane do what you cannot do at your best."