Twins

Using two fuselages to make ONE airplane

Although not very known, twins have been flying since 1915. The first was a design, named Fokker M9 or K1 (Kampfflugzeug), by the Dutchman Anthony Fokker. He lived at that time in Germany.

Fokker used two M7 fuselages and mounted them together to form the M9. The M7 was a biplane. On the outsides he placed the original wings and between both fuselages he placed a new wingsection as upperwing. The lowerwing was a combination of a wingsection and a short fuselage. This new fuselage had the original engines of both M7's. One was mounted in the front and one in the back driving a pusherprop.
Fokker placed in each M7 fuselage a gunner in the front (where now no longer the engine was mounted). Those gunners could now shoot next to the propeller. At those times you couldn't shoot through the propeller. Later Fokker designed a system that could.
The first flight was done without the gunners. The plane was very tailheavy and hard to control. This means that the CG (center of gravity) wasn't placed on its designed place, but more backwards. This isn't hard to believe when you know that the gunners were placed before the designed CG. So... flying without them shifted the CG backwards. Another problem during the first flight was that the fuselages rotated in relation to each other. The structure wasn't stiff enough to keep the fuselages nicely lined up.
Another flight was made with mechanics sitting in the gunnersplace. Flight behavior still wasn't good and the whole project was cancelled and the testplane scrapped.

Twins aren't always a failure.

Probably the only well known German twin: the Heinkel He 111 Z (Zwilling)

In World War II the Germans made a huge glider, the Messerschmidt Me 321 (see Giants). It was so large and heavy that 3 twin-engine Bf 110 fighters had to be used together to tow the glider in the air. These triple tows or "Troika-Schlepps" were very dangerous to all planes involved.
Generaloberst Ernst Udet, who did support several weird designs during WW II, came with the idea of making a twin, the He 111 Z (Zwilling), out of two Heinkel He 111's. This way he hoped to create a heavy transport that had the necessary power to tow the Me 321. Early in 1941 work began on two prototypes. They used He 111 h_6 fuselages and created a new wing section between the two inner engines. In this section they placed a fifth engines. Controls were divided between the fuselages. I quote one of my resources ("The Warplanes of the Third Reich" by William Green; Publisher: Doubleday and Co.): "Two completed undercarriages retained and the pilot was situated in the portside fuselage with five throttles, full instrumentation, controls for the port undercarriage members and the radiator flaps for the portside pair of engines. The second pilot, situated in the starboard fuselage, was provided with dual flying controls but no throttles and operated the starboard undercarriage members and the radiator flaps of the center engine and starboard pair of engines. A mechanic, radio-operator ang gunner were accommodated in the port fuselage and a mechanic and gunner in the starboard fuselage, the second pilot acting as navigator." I surely hope that the pilot with the throttles never got shot. Flying this twin from the other fuselage without using the throttles must be hard... let's even say impossible to land safe (personal finding).
Sometimes the five engines were not enough to tow the heavy loaded Me 321 and they needed to use a 502 kg (1 100 lb) thrust rocket beneath each fuselage and two 1507 kg (3 307 lb) thrust rocket beneath the centerwing, one on each side of the central engine.
Towing the Me 321 was done with a cable which was attached to a cable which was fixed to both inner wing-fuselage intersections. But each fuselage could have its own cable when smaller gliders were towed. There were succesful trials where 3 Gotha Go 242 were towed by a single He 111 Z.

The He 111 Z was operational since the summer of 1942, but all the planned operations were cancelled due to not obtained strategic goals like necessary captured airstrips. Their first operation was to deliver Me 321's filled with supplies to the troops in Stalingrad. Bad weather and in-between landings on overcrowded airfields delayed the flights and when they reached Makeyevka it was too late.
I would have liked to see the faces of the pilots, who were standing on these overcrowded airfields, when they saw these huuuuuge gliders coming in for landing. I bet most made a quick prayer to protect their parked airplane.
The first real operational use of the He 111 Z - Me 321 combination was getting casualties out of the Kuban bridgehead. He 111 Z's took off with 30 casualties aboard while towing a Me 321, which carried more than 100 casualties.
Many other operations were planned, but all were cancelled...again. This was not due to the airplanes, but due to the bad situation the Germans were near the end of the war.
Of the 12 delivered H 111 Z 4 remained at the end of the war. The rest was shot down or damaged during Allied bombing.

Heinkel He 111 Z

Dimensions
Span 35,2 m 115 ft 6 in
Length 16,7 m 54 ft 8 in
Landinggear track 10 m 32 ft 10 in
Take-off weight 28.375 kg 62 500 l

 

Performance

Max. speed at 4880 m (16 000 ft) 477 km/h 298 mph
Range 1890 km 1180 mls

Powerplant

5 x Junkers Jumo 211 F 12-cylinder liquid-cooled engines, each rated at 1300 hp (1768 kW) at 3810 m (12 500 ft)
Fuel capacity     4270 liter     940 UK gal

Another German twin was the Messerschmidt Me 609. It was formed by two Me 309-fighters. The Me 309 was intended as a replacement for the Me 109, which had no longer a superior performance in relation to the Allied fighters like the Supermarine Spitfire. It also lacked the necessary range. But the Me 309 development did progress very slow.
Only nine Me 309's were planned. The tests with the first Me 309 showed several teething problems such as overheating engines, wobbling and snaking groundhandling, high control forces. At the time when the 3th Me 309 was made, the Me 262 was already in production. The Germans saw no future in the further development of the "obsolete" piston-engine fighter.
But somehow there was a proposal of making a Me 609 out of Me 309's.

Why they made this proposal, what advantage it would have had ... I don't know. Could this Me 609 be related with the F-82 Twin Mustang (a Allied proposal which did start at the end of WW II)? Can anyone give me more details?

I would like to thank a person with callname "NiteWolf" for giving me the data on the Me 309.

Messerschmidt Me 609. If Fokker had used a similar tail connection, his M9 would have been stiffer.

3D drawing of a Me 609 by Graham Ward. Thanks Graham. Nice work!


On 03-06-2001 I got a remark from Erik Bakker: " I read your page on twin aircraft, but I missed a section on the Messerschmitt Bf 109Z version. I noticed your questions of where the origin was for building the Bf 309Z. Perhaps this info is the 'missing link'. * Somewhere during 1941 work began on a experimental heavy fighter/ bomber version of the Bf 109 F. Two airframes were connected to a parallel chord center wing section to form a Bf 109Z. It was equipped with two 1.350 hp DB 601E-1 engines and had a span of 43ft 61/3in (13.27 m). The sole prototype was damaged before first flight in an allied attack. Perhaps this project got a second chance with the development of the Bf 309. Further (and much more detailed) info on the Bf 109Z can be found at http://world.std.com/~Ted7/bf1092.pdf. Some info in these article point in opposite directions but I'll not be the judge to that.
* 'Combat Aircraft of world war Two' written by Elke C. Weal, John A Weal and Richard F. Barker. with Editorial Consultant J. M. Bruce and written in co-operation with the RAF Museum in Hendon."

P51+P51=F82. Maths by a mad teacher? No no, just a description of another twin. During WW II the Mustang or P51 was known for its longer range. It could escort bombers to Berlin. But these flights were very long and a fighterpilot couldn't count on a co-pilot to prevent fatique. A tired pilot could make wrong and lethal decisions when encountering a enemy.
Now, what to do if the range of the bombers becomes even longer? This question became active when Consolidated Vultee B-24's (English version got callname "Liberator") and Boeing B-29 "Superfortresses" entered service in the Far East.

Range bombers European and Far East theather
B 17     Normal at 352 km/h (220 mph) at 7625 m (25 000 ft)     1760 km     1 100 miles
B 24     Normal at 379 km/h (237 mph) at 7625 m (25 000 ft)     2462 km     1 540 miles
B 29     Longest range     6560 km     4 100 miles

North American Aviation did propose a simple solution. A twin-version of the Mustang. Why not? It could be constructed in limited time because the P-52 tools could be used. Some changes had to be made. The original wings had to be reinforced, a new tailplane and a new undercarriage was made. The port cockpit had all flight and engine controls, while the other cockpit only had enough controls to land the plane in a emergency or to let the co-pilot fly while the pilot takes a rest (or nap).

The Twin Mustang or F-82 with a central radar pod in a much used total black outfit. It sure must have been a scary experience for the enemy.


The F-82 came too late to play a role in WW II. Only 20 of the proposed serie of 500 F-82's were completed before VJ-Day (day of Japanese surrender). Even thought all production of non-jet powered aircraft stopped, some types were important enough to be used in the post-war plans of the USAF. The F-82 was one of them.
When the North Korean Army crossed the 38th Parallel into South Korea, the Korean War began. The only fighter to be able to depart from the American bases in Japan and have sufficient range to make sorties over Korea was the Twin Mustang. It was a F-82 who shot down the first enemy airplane, a Yak 11, a trainer who tried to get a shot at another F-82.
The F-82 could carry a pod under the midsection. This pod could house a additional six guns (never used in operations) or a radar. The black painted F-82G with its huge central radar pod was the most known version of the F-82.
Its operational career ended in 1953.

The reason for the very long pod can be found in the interference of the props. To keep the radar free of this interference it had to placed before the props. A very long pod was the solution.

If there is one airplane that could deserve the name Chameleon it would be the Piper Cub. The Cub has been changed in its history to many new needs. I have no idea what need did lead to the next variant of the Cub.

A twin-variant of the Piper Cub. Note the props which are placed VERY close.

If you say to yourself: "Hey, those props are too close to each other!", well, I did too. But if you look at the picture closely you will see that there is more shadow to the left of the right prop. I think that the right prop is placed a bit further forward than the other. This way they can turn without tearing each other apart.
Can somebody tell me why they did make this twin. Were they in need of a larger cargospace? Did they want a 4-seater? Did they want 2 pilots in the front? You tell me.

This site, http://www.fiddlersgreen.net/models/aircraft/Piper-TwinCub.html , has good extra info about the Piper TwinCub.


Another twin I found was the Fouga C.M. 88-R "Gemeaux" (Twin). It is a twin version of the Fouga C.M. 8 Cyclope. It uses its fuselages, its typical V-shaped tails and the outer wings. They made a new wing section between both fuselages and made a connection under the tails (it is just visible on the frontal picture). This twin was a testbed for the light Turboméca jet engines.

The Fouga C.M. 88R "Gemeaux".

A frontal view on the "Gemeaux". Just visible is a connection under the two V-tails.

I was searching info about a very simple glider, the LAK-16, when I ran into this picture. I was amazed. A recent development of a twin! The origin is the known Blanik-glider. All I had was a picture, no data. Christophe Meunier (better known as the writer X. toff for his books about twin-boom aviation) was so helpful to give me his data. I called this one the "twin-Blanik".

The "twin-Blanik" (permission to use picture from Linas Bartkevicius, manager of AB Sportine Aviacija)

Christophe Meunier gave me: "Name : SSAKTB SL-2P (SSAKTB = Specialus Sportives Aviacijos Konstravimo Technologinis Buras = Special bureau of sport aviation design and technology)
Source : Jane's All the World Aircraft 1988-89 page 643
History : Soviet glider (lithuanian) for aérodynamic studies, used to carry wing profiles under test. First flight : June 25th 1987. Manufactured by linking 2 Czechoslovakian gliders L-13 Blanik. One prototype has been made, probably one only (enough for the required testing). Two-seater : tandem cockpits in the port fuselage. Span 18.8m - Length 8.4m - Weight 0.79t empty and 0.95t maximum."

I got a mail from "Rusty" (Donald Fulford, d-fulford@raytheon.com), he mentions the existence of another type of twin. But he likes more data. Can anybody help him?: "Years ago I saw a picture of a twin Air Coupe, in FLYING MAGAZINE. It was built by an air show pilot. It was joined with a new center section main wing, and one of the twin vertical tails was removed and the horizontal tails attached. This gave it a triple tail similar to a constellation. The left wing and fuselage was painted in one stripped pattern and the other wing and fuselage were painted in a contrasting stripped pattern. This made the twin look like two aircraft in very close formation. The aircraft was used for aerobatics. I am thinking of building a 1/4 scale R/C version. I wonder if I could find two real air coupes, cheap enough to build a replica? If you already know about this aircraft and have pictures could you email copies to me?"

I got mail from Christophe Meunier (Better known as X. Toff, a writer). He listed for me A LOT of twins. Man, I didn't know there were that many twins around!

X. Toff wrote some books about twins. He mentioned me on the 4th August 2003 that he finished a new book about twins. Go see http://cmeunier.chez.tiscali.fr/index.htm. Sure is good stuff. The English version of his Asymmetric-twins page can be found at http://cmeunier.chez.tiscali.fr/asym_dahu_aeroUK.htm

« As reference data, here is an adding from Christophe Meunier (X. Toff as a writer), international expert for twin-boom aviation at the Air Britain association of aeronautic historians : * In my (French) book "Fantômes Fourchus" published in 1998/2000 ("Forked Ghosts, the twin-boom projects designed between 1939 and 1945" (see http://www.la-plume-du-temps.fr/2-12.htm) are illustrated the twin-planes of WW2 : - Twinning projects, like the He 111Z : North American Twin-P-51G / XP-82 Twin-Mustang, Reggiane Re 2005 Bifusoliera, Macchi C205 Bifusoliera, Fiat G-58 (G-55 Bifusoliera), Messerschmitt Bf 109Z / Me 409 (209Z) / Me 609 (309Z) / Me 509Z / E 2-26 (209Z'), Dornier Do 335Z / Do 435Z, Junkers Ju 635 (Do 335Z'), Heinkel He 111Z-4m/3m, Klemm/DFS Kl 25Z, Blohm und Voss P.167 (Bv 250Z), DFS 203 (230Z), General Aircraft Twin-Hotspur, Slingsby T-27 Black Widow (Twin-Cadet) ; and fake ones : Boeing/Nomura Twin-Fortress (Twin-B-29), Blohm und Voss/Nomura Bv 426 (Bv 226Z). - Twin-fuselage projects without twinning, like the Ar P.530 (or E 530) : Savoia-Marchetti SM-92, Lockheed Recon P-38, Pemberton-Billing PB-43/47 Venturi, Kaiser Flying Cargo Ship, Kaiser-Hughes HK-1 Liberty, Blohm und Voss P.123/125, Snead XLRH-1, North American RD-1120, Caproni Ca 380 Corsaro, PWS 46, Renard R 42, Tachikawa Dai-Ni-An/Dai-San-An, Bréguet Br 850/500t/1000t, SSSR-123, DFS 332. * In my forthcoming book "Supplement #1 to 'Forked Ghosts'" (publishing scheduled for February 2003) are illustrated further twin-planes of WW2 : - Twinning projects, like the He 111Z : CAPRA R90 (Double R80), Junkers Ju 290Z, Messerschmitt Me 323Z, Winkler Doppelrumpf ; and many fake ones : F+W D-3805 (Double D-3801), Republic/Gifford P-47 Doublebolt, Curtiss/Nomura P-40 Twin-Tigerhawk, Hawker/Lloyd Hurri-Twin, Caudron/Pug C714 TE, Heinkel/Tucker He 162Z Volkszwilling, Messerschmitt/Meunier Me 163Z, Supermarine/Durling-Spackmans-Felicioli Twin-Spitfire, Focke-Wulf/Baker Fw 190Z, Focke-Wulf/Bagnall Ta 152Z, Focke-Wulf/Mumford Ta 183Z, Messerschmitt/Shestakov-Brooks-Zuijdwegt Me 262Z, Gloster/Higgs Twin-Meteor, Douglas/Winthrop C-53 Walla-Walla (Twin-Skytrooper), Avro/Bagnall Warrior (Twin-Lancaster), Junkers/Wearmouth Ju 52Z, Dornier/Meunier Do 18Z, Dornier Do 417 (217Z), Heikel He 219Z, Dornier/Fordham P.256Z, Blohm und Voss/Nomura Bv 238Z, Consolidated/Nomura Twin-Model-36 (Twin-Peacemaker), Mitsubishi/Miura Twin-Zero A6M3-Z/A8M1, Kawanishi/Ishiduka Twin-Shiden. - Twin-fuselage projects without twinning, like the Ar P.530 : Blohm und Voss P.166, British unknown asymmetric, Rosatelli CR.50 (no picture for this one, does anybody know it ?) ; and fake ones : Blohm und Voss/Shestakov Bv 241, Lockheed/Winthrop Kiwi, Tupolev/Nomura Gigantskii,. - That does not include Mistels like the Me262/262, that has been featured as a plastic model in the MPM catalogue. * In my private twin-fuselage database, I have also recorded : - Twinning projects, like the He 111Z : Fokker M9/K I (Twin M8, 1915) Blackburn TB (Twin L, 1915), Voisin Type O (double M, 1915), Khioni/Anatra 4 (Twin Anade/Anasal, 1916), Boeing Twin-Boom 747, Lockheed Twin B007 (Twin-C-5), TsAGI Twin (Twin-An-225), Fouga CM.88R (Double CM.8), Vickers Two-fuselage VC-10, SSAKTB SL-2P (Twin-Blanik), Wagner Twin-Cub, Twin-Ercoupe, Schweizer SA 2-38 Condor (Twin SA 2-37), Dassault Twin-Ouragan ; and fake ones : Lockheed Twin-C-141, Douglas Twin-Skyhawk, BAe Twin-Harrier, McDonnell Twin-Phantom, Convair Twin-Hustler, BAC Twin-Lightning, Lockheed Twin-Starfighter, Hanger Twin-Guppy. - Twin-fuselage projects without twinning, like the Ar P.530 : Wight Twin-Seaplane (1916), Avro 721 Slip-Plane, Bestetti-Nardi BN.1, Rutan 202-11 Boomerang, La Bourdette-Halbron HT.1, Mc Donnell-Douglas Cryoplane, Avia LE P-3.4, Tupolev ANT-22/MK 1, Blériot 77/350/370, Zschach R, Adlershof R, Devoize bifuselage, Letov S 41/56, Martin Twin-Hull Ocean Plane, LAF Desmons, DTD Twin-fuselage, Schmued-Beeman-Balfour Twin-fuselage fighter, Albert bifuselage, Lockheed 1937, Belyayev DB-LK, Payen Pa.445/P.360TP/361/362/370, Molniya-1000, Hamburger P.13, Custer ?, Blohm und Voss Patent 685480, NASA Ames, CLST LP-901, Clarkson Golden Flight, Junkers J-1000/Junkerissime, Avicraft model, Martin 1938, Komet 1953, Saalfeld Möwe, Boeing 320, Horkey Twin-Mustang-Racer, Pennypacker & Patterson 1931, Super Stik 60, Martin Spacemaster booster, Sarpolus Twin Cut, Myassichchev MGS-6/8, Leduc 030, WIG S-90-200 ; and fake ones : Mc Donnell S2B Kestrel, Pulverizer, Trench Art Biplane T123, Dollarkönigs, Winthrop Dual-fuselage triplane. - Focused on twin-boomers, carrying a tailpane (or foreplane), I have not recorded the twin-pod flying wings (Fauvel binacelles, Khai-3, etc), sorry... This is all, as far as I know - you understand why I needed to focus on 1939-45 years for writing and illustrating a book on such a subject...
Help requirement : apart of twin-planes and twin-fuselage aircraft, I am interested in twin-boomers with a central pod, and for this, I am desperately looking for one source : Flying review August 1945 (a Mr Kotuba article about the ideal post-war aircraft, called Airsedan). Does anyone have it ? Thanks a lot."»

I could add this next twin, the Twin-Ercoupe, thanks to the hard work of Sam Berliner III. He contacted the owner of this picture, Grady Thrasher III, and could give me his permission to use this picture. Sadly the site of Sam Berliner III filled with weird airplanes is down. If you know where it can be found today, please, tell me.

The Twin-Ercoupe, pictured here at some airshow. Thank you very much, Sam Berliner III and Grady Thrasher III, to give me this picture. Click the picture to get to Sam's site and read more about this airplane or any other weird airplane in his site.

I was happy to see the Pipistrel Taurus 4. A modern electric airplane. And yes ...it uses the fuselage of the Pipistrel Taurus...twice. If you wonder why it was designed this way, just go see the video. It tells it all.

 

Thanks to Taja Boscarol, public relation manager of Pipistrel, i was able to get some pictures of the project. Info at: www.pipistrel.si

Pipistrel Taurus G4, a pure electric airplane.

 

Just imagine when you need to design it all from scrath again. The canopy, the cockpit, the landing gear, the controls. That would have taken a looooooot of time!

 

No wonder they used something that had nearly all what was needed. No redesign of cockpit, landing gear, canopy, ... . All was used of the Taurus. They added a new center wing section and the new powerplant-battery pod. Clever thinking! And ...it got the project fit in the tight time schedule.

My opinion about twin:


hmmm....seeing these examples I think that twins were only used as hasty solutions for a typical temporary problem. Assembling a twin was done much faster than designing a completely new airplane and making the necessary tools and rigs.

But they also had some disadvantages.

The F-82 had two single cockpits. The co-pilot couldn't help the pilot if he got shot. He could only fly the F-82 to the nearest base. Once there the first aid could be done... maybe too late.

The He 111Z had twice the internal volume of the H111. But I bet that a new freighter with the same total volume could carry larger parts. Just look at the Super Guppy (see "Giants"). A wider fuselage gives the possibility to load larger parts.

Imagine if they would even have used the He 111Z as a bomber. It would be a BIG problem if one fuselage had a release problem during the bombing. The asymetrical load would flip the airplane on its back.

One thing still puzzles me. Fauvel, a French airplane manufacturer specialised in unswepted flying wings (go see the Fauvel section in the Nurflugel site), did propose some military airplanes. I found some pictures of them in the book "Les Ailes Volantes" by Alain Pelletier (ISBN 2-7268-8444-X). It mostly are twins. But he didn't use existing fuselages. Every project had a new fuselage (actually two of the same design). Why????? Did he attempt to reduce the side area to prevent being hit by fighters? I have no clue. Can anyone help me clear this one out?

Another similar project was the Arado P530 (go see www.luft46.com) . It enhances two newly designed fuselages. But this project got cancelled because it had no advantages when compared to the H 111 Z. It even had disadvantages, due to the fact that the H 111 Z had very few new parts, most were stock H 111 parts. I guess that this would have killed all the Fauvel asymmetrical proposals before they left the drawingboard.

A few related sites:

The site of Christophe Meunier:
http://cmeunier.chez-alice.fr/index.htm

A page about the French "Gemeaux" (In French):
http://pletav.free.fr/avionsplan/lesgemeaux.htm