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Could the Me 109 Become a Jet Fighter?
Inside the 1943 feasibility study that weighed a Me 109/155 jet conversion against staying the course with the Me 262 — and why the numbers wouldn't cooperate.
01 Summary of Findings
A wartime engineering memorandum set out to answer a deceptively simple question: should jet-fighter production shift away from the purpose-built Me 262 and onto a converted Me 109 airframe — internally designated the Me 155 — fitted with Jumo turbojets? The motive was standardization, paired with pressure for faster delivery.
The analysis concluded that mounting Jumo jet units on the Me 155 was technically achievable, but amounted to nothing more than a stopgap. Despite a modest edge in material economy, the design was undercut by serious structural drawbacks: a dangerously shifting center of gravity, the need for substantially enlarged tail surfaces, and aerodynamic risk at high Mach numbers. With a pre-production run of 130 Me 262 aircraft already underway and flight testing well advanced, abandoning the Me 262 could not be justified.
02 Why the Question Was Asked
The inquiry grew out of a separate debate over whether the Me 309 was still justified alongside a DB 603-powered Me 109. As the Luftwaffe pushed to consolidate its aircraft around fewer base designs, planners wanted to know whether an entirely new jet airframe (the Me 262) was really necessary — or whether a modified Me 109/155 could do the job instead. The study proceeded on the assumption that the existing pre-production batch of 130 Me 262s would still be completed for extended flight trials.
The investigation drew on a specific set of archive drawings and weight records:
| Document | Description | Date | Scale |
|---|---|---|---|
| General arrangement drawing | Me 409 III/320, "special carrier-borne single-seat fighter" with Jumo 213 | 07 Apr 1942 | 1:10 |
| Weight breakdown | Me 155 with DB 605 | 27 Nov 1942 | — |
| General arrangement drawing | Me 109 G (8-109.G-1 Sheet 2), assembly, profile and plan view | 23 Jul 1942 | 1:10 |
| Sketch | Nose-wheel unit weights, Me 309 (III/247) | 23 Jan 1942 | — |
| Powerplant outline | Jumo jet unit per Me 262, side view (II/127) | 14 Jan 1943 | 1:10 |
03 Design Assumptions & Layout
- Weight & Wing Based on an expected all-up weight of roughly 5 tonnes, the existing Me 155 wing (19.5 m²) was retained so as to match the Me 262's wing loading.
- Undercarriage & Engine Placement To keep hot jet exhaust off the runway surface, a nose-wheel layout borrowed from the Me 309 was specified. Because the main gear had to retract behind the main spar, it needed 700×175 wheels — forcing awkward aerodynamic "bulges" on the upper wing surface. The jet units themselves were slung beneath the main spar.
- Armament & Fuel The plan called for two MK 103 cannon (100 rounds each) and one MG 151 (170 rounds) in the nose. A further pair of MK 108 cannon in the wing root was dropped due to center-of-gravity problems. Fuel capacity of roughly 1,400 litres was split across a forward tank (500 l), an aft tank (450 l), and an upper tank (450 l).
- Center of Gravity & Armor The Me 109's armor protection was dropped given the aircraft's high speed. The center-of-gravity constraints forced the armament as far forward in the fuselage as possible.
04 What the Numbers Showed
Take-off weight came to 4,750 kg — and that figure excluded a pressurized cabin, the necessary fuselage reinforcement, and the heavier tail surfaces the design would actually require. The center of gravity proved badly unstable, ranging from 25% (empty) to 32% (at take-off weight) and as far as 37% once ammunition was expended. The report doubted this drift could be engineered away.
Speed
Likely comparable to the Me 262, possibly slightly higher thanks to a smaller frontal area — but with a real risk that the Me 109's wing profile would fail at high Mach numbers.
Climb Rate
Expected to beat the Me 262, owing to lower overall weight.
Range
Slightly worse than the Me 262: roughly 1,500 litres of fuel versus the Me 262's 1,640 litres.
Handling & Visibility
Low-mounted thrust well below the center of gravity, combined with the loss of propeller wash over the tail, demanded much larger horizontal and vertical stabilizers. Visibility suffered too, with the cockpit set far aft and the engines projecting forward — though this alone wasn't disqualifying. The engines also induced extra torsional loads on the wing structure.
05 Production Reality
Very little of the existing Me 155/109 tooling could carry over unchanged. The report judged that the jigs and production planning required would amount to essentially starting fresh.
Reusable (with modification)
Me 155 wing (reinforced against twisting, revised flaps and cutouts) · Me 155 cockpit (new engine control linkages) · Me 155 fuselage tube (substantial reinforcement for tail loads, wheel and tank cutouts) · Me 309 nose-wheel gear (unchanged).
Built from Scratch
Enlarged horizontal and vertical tail · forward fuselage (weapons bay and nose-wheel well) · main undercarriage (shorter struts, larger wheels) · all fuel tanks, and likely a new radio fit.
06 Me 155 (Jet) vs. Me 262, Side by Side
| Category | Comparative Assessment |
|---|---|
| Armament / pressure cabin | Roughly even — strong armament and a pressurized cabin achievable on either design. |
| Material cost | Me 155 (jet) even or slightly ahead. |
| Bomb carriage | Equally difficult on both — both need a separate auxiliary undercarriage. |
| Speed / climb | Me 155 (jet) theoretically slightly ahead, on weight and frontal area. |
| Visibility / center of gravity / wing profile | Clear disadvantage for the Me 155 (jet); unsightly wing "bulges." |
| Testing status | Major advantage to the Me 262 — flight testing already well underway. |
07 Final Verdict
Abandoning further development of the Me 262 was not justified. The Me 155 conversion carried serious design flaws that even a layout change — such as moving the cockpit forward, as in the F 1080 project — would not fundamentally fix. Since the Me 155 (jet) offered no schedule advantage over the Me 262 for reaching series production, preference went to the Me 262 and its already advanced testing program.
Should a forced shift to substitute materials — steel and wood — become unavoidable, the memo noted, a separate question would need answering: whether an enlarged, jet-powered Me 328 might make more sense as a stopgap fighter than one based on the Me 155.
— About the Artist
The renders illustrating this piece reconstruct the Me 155 TL concept described in the original 1943 memorandum — visualizing the underslung jet units, the Me 309-derived nose gear, and the awkward wing "bulges" the report itself flagged as a weakness.
