As you all probably know the German Air Force in 1939-45 was concentrated in basicly 2 tipes of single seat piston engine Fighter, the Messer Me-109 and the powerful Focke-Wulf FW-190.
Nevertheless there was also several other tipes and designs wich were intended to replace and complemented it.
This is not about future projeckts by the way.
He-112.
He-112 development.
During 1933 the Technisches Amt (the technical department of the RLM) concluded a series of research projects into the future of air combat. The result of the studies were four broad outlines for future aircraft:
Rüstungsflugzeug I for a multi-place medium bomber
Rüstungsflugzeug II for a tactical bomber
Rüstungsflugzeug III for a two-place heavy fighter
Rüstungsflugzeug IV for a single-place fighter
The Rüstungsflugzeug IV was intended to be a Verfolgungs-Jagdeinsitzer (single-seat fighter), and the requirements were not terribly hard to meet. The plane needed to have a top speed of 400km/h at 6000m (250mph at 19,500ft) which it could maintain for 20 minutes, while staying in the air for a total of 90 minutes. It also needed to be armed with at least three machine guns with 1000 rounds each, or one 20mm cannon with 200 rounds. One other interesting specification was that the plane needed to keep wing loading below 100kg/m2, which is a way of defining the plane’s ability to turn and climb. The priorities for the plane were level speed, climb speed, and then maneuverability (in that order).
In October 1933 Hermann Göring sent out a letter requesting aircraft companies consider the design of a “high speed courier aircraft” — a thinly veiled request for a new fighter. In May 1934 this request was made official and the Technisches Amt (the technical department of the RLM) sent out a request for a single seat interceptor for the Rüstungsflugzeug IVrole, this time under the guise of a “sports aircraft”.
The specification was first sent to the most experienced fighter designers, Heinkel, Arado, and Focke-Wulf. The request was later sent to newcomer Bayerische Flugzeugwerk (Bavarian Aircraft Manufacturers, or BFW), on the strength of their Bf 108 “Taifun” advanced sports plane design. Each company was asked to build three prototypes for run-off testing. By the spring of 1935 both the Arado and Focke-Wulf planes were ready.
The primary source of inspiration for the 112 is the earlier He 70 “Blitz” (Lightning). The Blitz was a single engine, 4-passenger plane originally designed for use by Lufthansa, and it in turn was inspired by the famous Lockheed Orion mailplane. Like many civilian designs of the time the plane was pressed into military service, and was used as a two seat bomber (although mostly for reconnaissance) and served in this role in Spain.
Vs the BF-109
The Contest
The 112V1 started off the head-to-head contest when it arrived at Travemünde on the 8th of February, 1936. The other three planes had all arrived by the beginning of March. Right away the Fw 159 and Ar 80 proved to be rather lacking in performance, and plagued with problems. It was clear that the contest was really between the He 112 and the Bf 109.
At this point in the program the 112 was still the favorite over the “unknown” 109, but opinions changed when the Jumo powered 109V2 arrived on the 21st of March. From that point on it started to outperform the 112 in almost every way, and even the arrival of the 112V2 with the Jumo engine on the 15th of April did little to address this imbalance.
As would be expected the 112 had better turn performance due to it’s larger wing, but the 109 was faster at all altitudes and had considerably better agility and aerobatic abilities. During spin tests on the 2nd of March, the 109V2 showed no problems while the 112V2 crashed. Repairs were made to the plane and it was returned in April, but it crashed again and was written off. The V1 was then returned to Heinkel on April 17th, and fitted with the clipped wings.
V1 first proto.
V2.
Meanwhile news came in that Supermarine had recently received a contract for full scale production of the Spitfire, and this caused a wave of concern in the higher command of the Luftwaffe. Time now took on as much importance as any quality of the plane itself, and the RLM was ready to put any reasonable design into production.
That reasonable design was the Bf 109. On the 12th of March the Commission wrote up the outcome of their meetings in a document called “Bf 109 Priority Procurement”. The plane that was considered a long shot for most of the program suddenly found itself leading the race. But there were some who still favored the Heinkel design, and as a result the RLM then sent out contracts for 15 “zero series” planes from both companies.
Testing continued until October, at which point some of the additional zero series planes had arrived. At the end of September there were four He 112’s being tested, yet none was a clear match for the 109. This was likely the final nail in the 112’s coffin, from October on the Bf 109 appears to have been selected as the winner of the contest.
How about the Fw 187? I included that in my alt WW2 novel, The Foresight War 
Tony Williams: Military gun and ammunition website and discussion forum
I read the sample, pretty interesting.
By the way yes the Fw-187 was a very good twin engine fighter and one of the great “What if” of the Luftwaffe.
He-112 “Kanovogels”
Probably the first german aircrafts designed to combat armor.
When it was clear the 112 was losing the contest, Heinkel offered to re-equip V2 and V6 with 20mm cannon armament as an experimental aircraft. The Technisches Amt was very interested; at the time many tanks were equipped with 20mm guns as their primary armament, the same armament on a plane could prove to be a powerful weapon.
In September a 20mm MG C/30L cannon was mounted to the plane, with the breech to the rear of the engine and the barrel lying between the cylinder banks and exiting in the propellor spinner and feeded by a 30 roud drum magazine. This is the first experimental mounting of what would later be called the motorkanone, a feature that wanst new, this layout was used by the french in some fighters from la late 20s.
MG-C-30 20 mm cannon.
She was then broken down and shipped to Spain on the 9th of December.
After being re-assembled she was assigned to Versuchsjagdgruppe 88, a group within the Legión Cóndor devoted to testing new planes. There she was nicknamed the Kanonenvogel, and joined three V series Bf 109’s which were also in testing.
The Kanonenvogel was adopted by Oberleutnant Günter Radusch who started flying the plane on the 9th of December at Tablada. From then on it joined the Ju 87A’s and Hs 123’s already in service and was used as a ground attack plane. On the 6th of February the plane was moved to Villa de Prado near Mardid, and then in March she was re-assigned to Jagdgruppe 88 at Almorox near Toledo.
While sitting at Almorox due to a mechanical problem in his He 45C, Oberleutnant Wilhelm Balthasar heard that a Republican armored train was approaching and talked himself into the cockpit of the V6 by insisting he was a Heinkel test pilot. After teaching himself to fly the plane and managing to get into the air, he found the train parked at the station in Seseña and attacked it. On his third pass one of the 20mm shells punctured the ammunition car and the entire train exploded. Then on the way back to Almorox he came across an armored car and set it on fire.
His exploit in the V6 made him famous, and Balthasar found himself in command of the newly formed combat group with the V6 and three He 45C recon planes. Over the next few months the V6 was flown by a number of pilots, and on the 6th of July Unteroffizier Max Schulze knocked out an additional number of armored cars. On the 19th of July Schulze was once again flying the V6 when the engine seized during landing. Schultze walked away from the resulting pancake landing, but the plane broke her back and was a writeoff.
Some of the “long” ammo fired by this powerful gun, the Mg-C-30 was a 2cm Flak 30 with incresed rate of fire. The 20x138 B cartrigdes had plenty more power than the MG-FF and MG-151 guns.
Armor piercing, 142 grams.
Explosive 120 grams. With tracer and self destruction. The initial muzzle speed was about 800-855 m/s.
I had understood that the cannon installation was not primarily intended for ground attack, but for aerial combat - the Bf 109 was supposed to mount this gun as well. The idea was to attack planes at long range. This is supported by the fact that various French fighters had 20mm cannon for aerial combat, and the Luftwaffe was inspired by them.
Once in Spain it was realised that long-range fire from a high-velocity cannon was not very practical, so the He 112 was used for ground attack instead. The cannon installation was also reckoned to be too heavy. So the Luftwaffe abandoned the idea and went to the other extreme of very light, low-velocity 20mm for close-in combat.
Tony Williams: Military gun and ammunition website and discussion forum
It maybe be intended to air-to-air combat but his role was changed.
I dont Think that that the 64 kg of a MG-C-30 were too big, The russian mounted heavy guns like the 23mm Ns-23 and 37 mm between the V-12 engines of relatively light fighters like Yak-9 and Lagg-3 with no too much trouble.
As you know the balistic of the Mg-ff was very poor compared with this, I think that a mistake drop out the developmente of this Mg, especially when the Luftwaffe sought a gun for the anti-bomber role later in the war.
The MG C/30L installation reportedly weighed 180 kg complete with full 100-round drum. That was a lot for a late-1930s plane, which did not have the power of later models. The ballistics were excellent, but the rate of fire was only 300-350 rpm and the gun was very long - it certainly could not have been wing-mounted in anything. I agree that the MG-FF ballistics were too poor, but the MG 151/20 was a good balance between ballistics, weight and RoF.
The Luftwaffe might have chosen the Oerlikon FFL rather than the FF - see THIS
Tony Williams: Military gun and ammunition website and discussion forum
The MG C/30L installation reportedly weighed 180 kg complete with full 100-round drum. That was a lot for a late-1930s plane, which did not have the power of later models.
Well, I did not have that information, I read somewhere that it used 30 o 60 round drums.
The Luftwaffe might have chosen the Oerlikon FFL rather than the FF - see THIS
Nice article. And with respect to the MG-151/20,…I think that was a good gun indeed, but I feel ( And this is probably a personal mania) wen I see some germn WW2 guncams that this 20 mm gun was a little underpowered, especially engaging single bombers at more than 250 meters in range.
The 2 cm Flak 38 ( the evolution of the Mg-C-30) was faster firing and probably it could be adapted to the V-12 fighters like Bf-109 without many trouble…Why they do not do that.?..I dont Know.
This was the MG-C gun layout in the crashed He-112V2.
Image from “Jagdeinziter He-112 Hans Peter Dabrowski/Waffen Arsenal”
Messer Me-309.
V1 with nose cap removed
The Messerschmitt Me 309 was a prototype German fighter designed in the early years of World War II to replace the Messerschmitt Bf 109. Although it had many advanced features, the Me 309’s performance left much to be desired and it suffered from so many problems that the project was cancelled with only four prototypes built. The Me 309 was one of several failed Messerschmitt projects intended to replace the aging Bf 109, the others being the Me 209 and the Me 209-II.
The Me 309 project began in mid-1940, just as the Bf 109 was having its first encounters with the Spitfire in the Battle of Britain, the first aircraft to match the 109 in speed and performance. Already Messerschmitt anticipated the need for an improved design to replace the Bf 109. The RLM, however, did not feel the same urgency, and the project was given a low priority and the design was not finalized until the end of 1941.
The new fighter had many novel features, such as tricycle landing gear and a pressurized cockpit which would have given it more comfortable and effective high-altitude performance. Each of the new features was first tested on a number of Bf 109F airframes, the V23 having a ventral radiator, the V31 with radiator and tricyle landing gear, and the V30 having a pressurized cockpit.
Low government interest in the project delayed completion of the first prototype until spring 1942 and trouble with the nosewheel pushed back the 309’s first flight to July. When it did fly, the Me 309’s performance was satisfactory but not exemplary. In fact, the Bf 109G could outturn its intended replacement. With the addition of armament, the plane’s speed decreased to an unnacceptable level. In light of its poor performance and the much more promising development of the Focke-Wulf Fw 190D, the Me 309 was cancelled.
cutaway view of the Messerschmitt Me 309
In 1943, Messerchmitt made one last attempt at creating a replacement for the Bf 109 in the form of the Me 209-II. It was essentially a modification of the existing 109 airframe, Messerschmitt designers not wanting to invest the time and trouble in a new design like the Me 309.
V2
Type: Single-seat fighter
Origin: Messerscmitt AG
Models: V1 to V4
First Flight: June 1942
Service Delivery: None
Final Delivery: None
Engine:
Model: Daimler-Benz DB 605B or DB-603A1
Type: Inverted V12 liquid-cooled
Horsepower: 1,475
Dimensions:
Wing span: 11.04m (36 ft. 2¾ in.)
Length: 9.46m (31 ft. ½ in.)
Height: 3.45m (11 ft. 3 in.)
Wing Surface Area: N/A
Weights: (V1)
Empty: 3530kg (7,783 lbs.)
Maximum: 4250kg (9,371 lbs.)
Performance:
Maximum Speed: 720km/h (V1 with DB-603)
In some ways this last design almost reminds me of the Me262 (other than obvious differences between piston and jet propulsion). Particularly the tail, canopy, tricycle landing gear and fuselage shape (somewhat).
I Think that was on purpose to sav development time, the germans adaptd tr tricicle landing gear late in war…i dont kow why.
Nice 3 view of the havily armed V4.
Two more images of the Me-309.
The nose gear layout…
wich was not his best caracteristic…
There was one totally consistent thing about Willi Messerschmitt’s designs - the undercarriage had a tendency to collapse.
I thought it highly appropriate that the undercarriage of one of the new-build Me 262’s collpased on landing a year or two back 
Tony Williams: Military gun and ammunition website and discussion forum
Might also account for the failure of the Kriegsmarine to put the Graf Zepplin into service - an airgroup of fighters that could only do one landing before being replaced would be a disadvantage.
The nose down in that picture was caused ( beside the weaknees) for the reversible pitch propeller used in the Me-309, that was maked to create aditional brake power in landing…but also this increase the stress in the the front wheel with the visible results.
Alternative cockpit layout.
He-112V7 an aicraft equipped with the powerful DB-601, with this it surparsed the performances of the BF-109Emil by far.
The semieliptical wing also give it good handling at dogfights. despite his good behavior the definitive He-112 variant, the Berta, used a much less powerful Jumo 210GA.
He-100 interceptor.
This pleasant looking fighter was another failed attempt by Ernst Heikel AG to compete against the Bf 109. Disappointed by the loss of the Luftwaffe’s fighter orders to BFW and it’s Bf 109 and the failure of the He 112, Heinkel set out to build a lighter and faster fighter that was also cheaper and easier to build. The resulting Projekt 1035 was completed on May 25, 1937 and by the end 1937 the RLM had sanctioned a prototype and ten pre-production machines. The prototype flew on January 22, 1938 was very fast but was disliked due to high wing loading. The He 100 achieved some of it’s speed by doing away with the anti-aerodynamic radiatoer and using a surface evaporative system for cooling.
Even though the He 100 broke several world speed records, the RLM was solidly supportive of the Bf 109 and failed to order the He 100 into production. Six prototypes were eventually sold to the Soviet Union and three He 100D-0 went to Japan. The three He 100D-0’s being armed with two MG 17 and a 20mm MG/FF. The remaining 12 He 100D-1 fighters were used to form a Heinkel-Rostock factory defense unit, flown by Heinkel pilots. However, in 1940, Goebbels publicised the He 100 to the extent that British intelligence reported the He 100 in large scale service as the “He 113”.
[b]He 100D-1[/b]
The final evolution of the short He 100 history is the D-1 model. As the name suggests the design was supposed to be very similar to the pre-production D-0’s, the main planned change was to enlarge the horizontal stabilizer
But the big change was the eventual abandonment of the surface cooling system, which proved to be too complex and failure prone. Instead an even larger version of the retractable radiator was installed, and this appeared to completely cure the problems. The radiator was inserted in a “plug” below the cockpit, and as a result the wings were widened slightly.
The clean lines of the He-100D-1 ( false denomination He-113)
While the plane didn’t match it’s design goal of 700km/h once it was loaded down with weapons, the larger canopy and the radiator, it was still capable of speeds in the 400mph range. A low drag airframe is good for both speed and range, and as a result the He 100 had a combat radius between 900 and 1000km compared to the 109’s 600km. While not in the same league as the later escort fighters, this was at the time a superb range and may have offset the need for the 110 to some degree.
By this point the war was underway, and as the Luftwaffe would not purchase the plane in its current form, the production of the He-100, the most advanced fighter of his time line was shut down after only 12 produced.
Specifications for the He 100D-1c
Engine: 1,175hp (876kW) Daimler-Benz DB 601M liquid–cooled inverted V12
Dimensions: span 9.42m (30ft 10 3/4in)
length 8.20m (26ft 10 3/4in)
height 3.60m (11ft 9 3/4 in)
Weights: empty 2070kg (4,563lb)
max loaded 2500kg (5,512lb)
Wing Area: 14.5m2 (156ft2)
Wing Loading: 29.25lbs/ft2
Performance: maximum speed 668km/h at 6400m (416mph at 21,000ft)
560km/h (348mph) at sea level
cruise speed unknown
service ceiling 11000m (36,090ft)
range 900km (559miles)
Armament: one 20mm MG/FF-M firing through the propeller spinner
two 7.92mm MG17 in the wings
Sources:
http://tecnica-militar.fateback.com/aereo/Heinkel%20100.htm
http://www.csd.uwo.ca/~pettypi/elevon/baugher_other/he100.html