Estonian Aircraft Designations


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Estonian Aircraft Production -- 1922-1940

[Q: Was the Narva Õhuasjanduse Ühingule also an aircraft maker/assembler ?]



Sablating P.III -- 1922-23 high-wing monoplane passenger a/c, x 6*
- P.III : Cabin parasol monoplane with open rear pilot's cockpit
- P.III : 1 x (??) possibly AS Puma or BMW IV 6-cyls; span 16.00 m
- P.III : Estonian-licenced P.III had overhung balanced ailerons
-- Built for A/B Aeronaut (Tallinn-Riga; Helsinki airmail service, etc.)
-- * Dvigital-built Aeronaut P.IIIs were registered E-7 through E-12**
-- ** Although iverson listed 10 x Dvigital-built Aeronaut P.IIIs [1]

Klemm L 25 - 1933 2-seat tandem monoplane trainer, x 1*
- L 25 : Low-wing, open cockpit basic trainer/touring aircraft
- L 25 : 1 x (?) 60 hp Hirth H.M.60 4-cyl. inline; span 13.00 m
- L 25 : Licensed from Leichtflugzeugbau Klemm GmbH
-- * ES-UBA (later ES-SAM); rebuild of crashed ES-UST
-- 1934 ES-AAC, built by Karl Lemm


[1] On iverson's list, a total of 10 x Dvigital-built Aeronaut P.IIIs are claimed. A/B Aeronaut P.III registrations are listed as E-1, E-2, E-3, E-4, E-6, E-7, and E-9. Other Dvigital-built P.IIIs listed were E-8 (AS Puma, to Lufthansa), E-11 (BMW IV, to Lufthansa), and E-12 (to Junkers, then to Lufthansa).


Sakalamaa Õhuasjanduse Ühing, Viljandi

Raab Schwalbe II - 1933 2-seat tandem biplane trainer, x 2*
- Schwalbe II: Raab-Katzenstein Schwalbe Kl 1 derivative
- Schwalbe II: 1 x 130 hp Walter NZ 130 9-cyl.;** span 8.00 m
-- * For use by the Tallinn Aviation Society; ES-AGU and ES-EHA
-- ** NZ 130 (possibly later replaced by a British 200 hp AS Lynx(?)


ÕGL = Õhu- ja Gaasikaitse Liit (Air & Gas Defence League, Tallinn)

RWD-8 - 1934 licensed-built 2-seat parasol monoplane trainer, 1 x built*
- RWD-8 : Licensed from Polish RWD firm, no ÕGL designation is known
- RWD-8 : 1 x 110 hp PZL (Walter) Junior inverted 4-cylinder; span 11.00 m
-- * ES-RWD for Eesti Aeroklubi; NB: RWD-8 ES-RVD was built in Poland

ÕGL-x Designations

ÕGL-1 - 1934 2-seat tandem biplane basic trainer/tourer, built x 3*
- ÕGL-1: 1 x Armstrong Siddeley Genet Major I 5-cyl.; span 7.30 m
-- * ES-PON 'Kai', ES-LDM 'Lendav Mulk', + 1 x aircraft sent to Latvia
- ÕGL-1: Later redesig. PON-1 (qv); followed by PON-1a & KOD-1

ÕGL-2 - 1934 2-seat tandem biplane club trainer/tourer, built x 3*
- ÕGL-2: 1 x 75 hp Pobjoy R 7-cylinder radial; span (??) m
- ÕGL-2: Possibly redesignated as 'PON-2'(qv); unconfirmed
-- * 3 built for Eesti Aeroklubi, prototype ES-ENN, -AIN, -EPP
-- 'PON' for designers Voldemar Post, Otto Org, & L Roman Neudorf

ÕGL Designations by Designers' Initials
surnames of Voldemar Post, Otto Org, and Rein Neudorf who later changed his name to Tooma.

PON-1 -- 1934 2-seat tandem biplane basic trainer/tourer, built x 20
-- Originally designated ÕGL-1 after Õhu- ja Gaasikaitse Liit (above)
- ÕGL-1/PON-1 : Original radial-engined variant, total of 3 x built
- PON-1 : 1 x Armstrong Siddeley Genet Major I 5-cyl.; span 7.30 m
- PON-1a: 1936-1937, inline-engined variant; 4 x built (#154-157)
- PON-1a: 1 x 125 hp DH Gipsy Major inverted 4-cylinder; span 7.30 m
-- KOD-1 : PON-1* license-built in Latvia by LKOD, 13 x built
-- * Built w/ Genet Majors then re-engined to PON-1a standard

PON-2 -- 1934 trainer; possible but unconfirmed designation; 3 x built
- PON-2 : Poss. false designation; may have remained ÕGL-2 (qv)
-- 'PON' for designers Voldemar Post, Otto Org, & L. Roman Neudorf*

PN-3 - 1939 2-seat recce/light fighter monoplane; x 1 (#160)
- PN-3 : 1 x 570 hp Rolls-Royce Kestrel XI V12, span 10.65 m
-- Named 'Isamaa Päästja' (Estonian: Savior of the Fatherland)
- PN-3 : Low-winged monoplane with fixed, spatted main u/c*
-- * Retractable undercarriage planned for production version
-- 'PN' for designers Voldemar Post & LR Neudorf (aka Rein Tooma)
- PN-3 : (Project) Prod'n variant; 1,000 hp engine; retractible u/c

PTO-4 - 1938-39, 2-seat, low-wing monoplane trainer, 8 x built*
- PTO-4 : Compare w/ Magister which Post was exposed to
- PTO-4 : 1 x 130 hp DH Gipsy Major inverted 4-cyl; span 10.00 m
- PTO-4a: Single prototype fitted with a glazed cockpit canopy
-- * Orders for 12 x military PTO-4s (#189-200) but not completed
-- * PTO-4 (#161) & PTO-4a (#162) prototypes built by Aviotehases
-- * Series PTO-4 built at the workshops of Eesti Aeroklubi; x 6**
-- *** ES-EAO and ES-EAP not deliv.; perhaps left unfinished(?)
-- 'PTO' for designers Voldemar Post, Rein Tooma, & Otto Org

(??) - (Project) Single-engined fighter (poss. PN-3 reference)

(??) - (Project) Twin-engined fighter aircraft


Antonius Raab - see Sakalamaa Õhuasjanduse Ühing


After their 1940 occupation, the Soviets began construction of a new factory - Zavod 463. There, it was intended to series-build the Lavochkin I-301 (LaGG-3) fighter beginning in December 1941. A production rate of 350 aircraft per year was planned (starting with a rather optomistic 50 x LaGG-3s in 1941). Zavod 463 was also meant to produce the Kolesnikov-Tsibin KTs-20 transport glider.

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Hi Apophenia,
Very interesting post! It is very difficult to obtain information about Estonian aircraft. The language barrier is hard to overcome, and automatic translation from this language is still of poor quality.
Here are some comments and additions.

Apophenia said:
[Q: Was the Narva Õhuasjanduse Ühingule also an aircraft maker/assembler ?]

It seems that "Õhuasjanduse Ühing" translates as "aviation society". (The word "Ühing", of which Ühingule is a declined form, has the meanings of society, association, union, league, etc...) The activity of those aviation societies is described here:

Narva is a town, and the "Narva Õhuasjanduse Ühing" was the local aviation society or aeroclub.
Among their activities were the creation of a local airfield, and there are hints that they had an aircraft built for them in Tallinn in 1935, but it could be one of the ÕGL/PON aircraft:

The local societies were federated first into the "Õhu- ja Gaasikaitse Liit" (Air and Gas Defense League), a paramilitary organization, which was disbanded in 1936 and became the "Eesti Aeroklubi" (Estonian Aeroclub):

Apophenia said:

Sablating P.III -- 1922-23, licenced high-wing monoplane passenger aircraft (2 + 6 pax), 6 built (E-6 - E-12) for airline, A/B Aeronaut (for daily Helsinki airmail service, etc.)

The first Sablatnig P.III aircraft, registered E-6, was built in Germany. Only the six following aircraft (E-7 to E-12 included) were built by Dvigatel in Tallinn:

Apophenia said:
Raab Schwalbe II -- 1934, 2-seat biplane trainer, 1 x 200hp AS Lynx, 2 built (ES-AGU, -EHA)
-- for Eesti Aeroklubile use
It seems that the two Raab Schwalbe II were also built by Dvigate in 1933l:
The Eesti Aeroklubi did not exist yet in 1934, and the Estonian wikipedia says that the aircraft were delivered to the Tallinn Aviation Society:

In the town of Viljandi, the "Sakalamaa Õhuasjanduse Ühing" or Sakalamaa Aerial Society did produce one or several gliders.

They also rebuilt a Klemm L25 ES-UBA from the remains of the crashed ES-UST of Baron Heinz Ungern-Sternberg ; it is not clear if the design was modified:
It is said that the aircraft was later re-registered ES-SAM:

There was another aircraft built at Viljandi by the "Sakalamaa Õhuasjanduse Ühing" and registered ES-AAC. Internet sources are difficult to understand and sometimes contradictory. The aircraft is sometimes reported as another Klemm L.25, and sometimes as a PON-2, which seems implausible. Construction of ES-AAC was supervised by engineer Karl Lemm for Ungern-Sternberg, as a replacement for the crashed ES-UST. ES-AAC crashed in 1934, killing Lemm. The pilot Ungern-Sternberg survived but sentenced to jail for a short time for having flown it illegally:
It is unclear if the rebuild of ES-UST as ES-UBA was done after this failure or simultaneously.

Apophenia said:
RWD-8 -- 1934, licenced 2-seat parasol trainer, 110hp PZL (Walter) Junior, 1 built (ES-RWD)
-- for Aeroklubile [ES-RVD was Polish-built]
I only found the Polish-built "ES-RVD" in an English-language registration list, but I'm not too confident in it:

Apophenia said:
'PON' or ÕGL = Õhu- ja Gaasikaitse Liit (Air & Aircraft Workshop, Tallinn)
"Õhu- ja Gaasikaitse Liit" was the Air & Gas Defense League, which later became the "Eesti Aeroklubi". It had its own workshops in Tallinn.

Apophenia said:
PON-1 -- 1934, 2-seat biplane trainer, 1 built (c/n 154-157)
-- Orig. ÕGL-1 'Kai' after Õhu- ja Gaasikaitse Liit (Air & Aircraft Workshop, Tallinn)
-- PON-1A -- 1936-1937, 2-seat biplane trainer, 4 built (c/n 154-157)
-- KOD-1 -- 13 PON-1 license-built in Latvia by LKOD
There were at least two examples of the original ÕGL-1 / PON-1, registered ES-PON and ES-LDM. The name 'Kai' was applied on the fin of the prototype ES-PON, it was perhaps specific to this aircraft. ES-LDM was called 'Lendav Mulk' and used by the "Sakalamaa Õhuasjanduse Ühing".
There was perhaps a third aircraft sold to Latvia:

It seems that Estonian sources use the name "PON-1a" rather than "PON-1A". Those were sold to the military, with a different Gipsy Major engine. Numbers 154-157 are not constructor numbers but serial numbers of the Estonian Air Force.

Apophenia said:
PON-2 -- 19??, 1 x 85hp ?, 3 built (for Aeroklubile, prototype ES-ENN, -AIN, -EPP)
-- Originally ÕGL-2
The ÕGL-2 first flew in 1934. The engine was a Pobjoy 75 hp. Estonian sources say that the name PON-2 is possible but unconfirmed:
See also the story of ES-AAC told above.

Apophenia said:
PN-3 -- 1939, 2-seat monoplane recce/light fighter, 500hp Kestrel, 1 built (#160)
-- Named 'Isamaa Päästja'. Retractable undercarriage planned for production version.
"Isamaa Päästja" means "Saviour of the Country".

Apophenia said:
PTO-4 -- 1938-39, 2-seat, low-wing monoplane trainer, 1 x 130hp DH Gipsy Major, 13 built
-- 2 for AF, others for Eesti Aeroklubile, PTO-4A (c/n 162) completed with glazed canopy
-- Another 12 planned for the minilitary (c/n 189-200) but not completed
-- Aeroklubile PTO-4s - ES-EAK, S-EAL, -EAM, -EAN, -EAO, -EAP (perhaps unfinished?)
The first military aircraft, a regular open cockpit PTO-4, had military serial 161, and closed cockpit PTO-4a had military serial 162.
The Estonian Wikipedia says that the PTO-4a had a more powerful engines, but official archives mention the Gipsy Major 130 hp for both models:

It is sometimes said that only four civilian PTO-4 were completed: EAK, EAL, EAM, EAN, and that EAO and EAP were left unfinished:
However there is a picture showing EAO in apparently flying condition, contradicting this version:

The total production of 13 seems wrong. Registrations ES-ASN and ES-CFI are mentioned in an English listing but not in Estonian sources, I think they are bogus:

I found no motor aircraft production after WW2, but Endel Helme, Hillar Link and Ülo Keedus built the HLK-1 glider ca. 1958, and Peep Lauk built a flying wing motorglider which first flew in 2009:
Other video at Youtube:
Many thanks for the corrections and clarifications Adrien! :D

I've left my Narva Õhuasjanduse Ühingule query for now. Many of these aviation societies/flying clubs seem to have assembled their own gliders, etc., in the 1930s.
here you have some extract taken from Estonian Auto-Sport & Turism in August 1933 about the Raab Schwalbe II.
As you can see, the Schwalbe II had the Walter engine, not the Lynx (at least in 1933, might have been changed later)
BTW: As some sources mention the Schwalbe II as a RK26 derivate ... it is clearly a Kl.1 design ...RK26 is wrong!

here you have some extract taken from Estonian Auto-Sport & Turism in August 1933 about the Raab Schwalbe II.
As you can see, the Schwalbe II had the Walter engine, not the Lynx (at least in 1933, might have been changed later)
BTW: As some sources mention the Schwalbe II as a RK26 derivate ... it is clearly a Kl.1 design ...RK26 is wrong!

Thanks for that luftfahrtarchive!

This thread needs a lot of working over [edit: Done. Comments/corrections welcome]. Alas, I cannot find my way back to my old source on the Lynx (for now, I'll leave it in as a 'possibility' ... just in case one or both of the Estonian Schwalbe II was re-engined later on.

On your contemporary source, odd that their 'N3-130' (sic) is listed at "114 hj" (or ~112.44 hp). Nominal power for the Walter NZ 130 (aka NZ 120 II) is usually given as 130 hp @ 1600 rpm.
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