View source for PTO-4

{{Short description|Estonian military trainer aircraft}}
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{{Infobox aircraft
 |name=PTO-4
 |image=Самолёт РТО-4А на лётном поле.jpg
 |caption=РТО-4А
 |type=[[trainer aircraft|Trainer]]
 |manufacturer= Aviotöökoda, [[Tallinn]] 
 |designer=Voldemar Post, Richard Tooma and Otto Org 
 |first_flight= 
 |introduction=1938
 |retired=1944
 |status=
 |primary_user=[[Estonian Air Force]]<br/>[[Luftwaffe]]
 |more_users=
 |produced=1938
 |number_built=8
 |unit cost=
 |variants=
}}
The '''PTO-4''' was an [[Estonia]]n-designed military training aircraft of [[World War II]].

In 1938, the Estonian aviation engineers Voldemar Post, Rein Tooma and Otto Org, previously responsible for the [[PON-1]] trainer, designed and built the PTO-4 training aircraft.<ref name="Gerdessen p71">Gerdessen 1982, p.71.</ref> It was a two-seat low-winged monoplane powered by a De Havilland Gypsy of 120&nbsp;hp, with a fixed undercarriage that could be fitted with wheels or skis.<ref>{{Cite web | url=http://www.histaviation.com/pto_4.html | title=Aircraft template }}</ref> The aircraft could fly at a maximum speed of 245&nbsp;km per hour and had a ceiling of 5,000 meters.<ref>{{Cite web | url=http://www.histaviation.com/pto_4.html | title=Aircraft template }}</ref> On 12 October 1938, the PTO-4 was taken into service of the Air Force.<ref>{{Cite web | url=http://www.histaviation.com/pto_4.html | title=Aircraft template }}</ref>

The [[Estonian Air Force]] received two PTO-4s (serial numbers ''161'' and ''162''), one with an open cockpit and the other an enclosed cockpit.<ref name="Gerdessen p71"/>  Six examples were in civil use,<ref>{{Cite web | url=http://www.histaviation.com/pto_4.html | title=Aircraft template }}</ref> of which five were used by the ''Eesti Aeroklubi'' (EAK), a flying club controlled by the Estonian Military.<ref name="Gerdessen p71"/>

Four examples surviving from the [[Soviet occupation of Estonia]] (1940–41) were operated by the German [[Luftwaffe]], being operated by a unit manned by Estonian volunteers (initially called ''Sonderstaffel Buschmann'' and later 1./SAGr.127) based at [[Tallinn Airport|Reval-Ülemiste airfield]]. They were operated as training and liaison aircraft as well for coastal patrol over the shores of the [[Baltic Sea|Baltic]].<ref name="Gerdessen p74-5">Gerdessen 1982, pp.74–75.</ref>

==Operators==
;{{EST}}
*[[Estonian Air Force]]
;{{flag|Germany|Nazi}}
*[[Luftwaffe]]

==See also==
{{aircontent|
|related=
*[[PON-1]]
*[[PON-2]]
*[[PN-3]]
|similar aircraft=
|sequence=
|lists=
* [[List of interwar military aircraft]]
|see also=
}}

==References==
{{reflist}}

*Gerdessen, F. "Estonian Air Power 1918–1945". ''[[Air Enthusiast]]'', Eighteen, April – July 1982. Bromley, UK:Pilot Press. pp.&nbsp;61–76.

==External links==
{{commonscat}}
*[http://www.post.ee/?id=1595&prod_id=66 Estonian Postage Stamp]

[[Category:Aircraft manufactured in Estonia|PTO-4]]
[[Category:Single-engined tractor aircraft]]
[[Category:Low-wing aircraft]]
[[Category:Aircraft with fixed conventional landing gear]]

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