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GOT: The 'Aviotehase' PN-3


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#1 Romantic Technofreak

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Posted 25 July 2014 - 05:46 PM

Let's have a GOT topic about this interesting and very beautiful aircraft from Estonia.

 

 

Explanations:

First of all. I have to tell you that there was no such firm like "Aviotehase". When you google for this word, you can find it as part of job descriptions. Splitting the word one knows "avio" being international, while "tehas" means just "factory" in Estonian language. In airwar.ru, you can find the machine as "Post & Neudorf PN-3". You can google for that, but googling for "Post" or "Neudorf" does not make much sense, as "Post" is "mail" and "Neudorf" is "new village" in German language (thank god I do know about this), pointing the constructors being of German origin.

 

So it was clear that for finding out the correct denomination of the aircraft, I would need some assistance. Via the Estonian War Museum, I got contact to Estonian aircraft historian Mr. Toivo Kitvel. He told me the correct denomination is just "PN-3", nothing else. About "Aviotehase" (with or without closing "e"), this is what he told me:

 

"In 1930ies Estonian Air Defense (Õhukaitse) consisted of three flying divisions, a flying school and an air-base. Aviotehas was the place where Estonian designed aircraft (like PTO-4) were built and where the aircraft belonging the Air Defense were checked regularly and repaired. (Small repair was done at the workshops of flying divisions). And as you must probably have guessed : Aviotehas was one “structural element” of the Air Base."

 

The manner of not giving a "real" constructor name for aircraft was quite frequent in earlier times. Mr Kitvel told me the DH.9 for example, later became famous as "Airco DH.9". And remember Polish aircraft denominations like "PWS-26".

 

So much is clear that "PN" is lent from the names of the leading constructors Voldemar Post and Roman Neudorf. About the latter, Mr. Kitvel wrote me: "Neudorf was christened as Ludvig Roman Neudorff, who shortened it to Neudorf and as far as I know never used the Ludvig. And to make things more complex – in the end of October 1935 he changed his name to an Estonian sounding: Rein Tooma. The decision to produce PN-3 was taken some months before he changed his name. (The trainer PTO-4 has its T taken from Tooma)."

 

Well, the Estonians seem to have some trouble with their national identity due to their turbulent history. When they visit their capital Tallinn, they go to "Taan-linn", meaning "Danish city", so they go to Denmark (pointing on the Danish rule 1219 - 1346). Mr. Kitvel's family also estonicized their name from "Kitwell" (English origin?).

 

 

To read:

The text is mainly from Estonian Wikipedia. Airwar.ru also delivers a quite wordy writeup, but does not contain much more information. Only things are Estonia was also interested in importing aircraft, but at the time considered she received only some Henschel Hs 126. And I got the test pilot's name from there.

 

Translating from a non-Indo-European language like Finnish-related Estonian is a special challenge, I can tell you. I thought to add some peculiarities as comments below.

 

 

 

The PN-3:

 

 

Purpose

PN-3 was designed as a reconnaissance plane (the Estonian word is "luure", seemingly some relation with "to lurk") and fighter trainer.

 

 

History

The first drawings of the aircraft were made in 1935 by an engineer named Küttner, who originated from a noble family of St. Petersburg and in 1937 moved to Germany (he went to "Saksamaa" = "saxon country"). The work was completed by Voldemar Post , Rein Tooma, and E. Lesta (Google translates the latter's family name literally: "flounder"). The plane was built in 1938. The first flight happened in January 1939 with test pilot Peter Olf at the controls. The first prototype was completed without armament installed and registered under number 160. As the Estonian Air Force at this time was on a weak level, the people named the new plane wisecrackingly exemplary "savior of the fatherland". Until the occupation of Estonia in 1940, PN-3 performed a total of 104 flights and flew a total of 31 hours. Within one year it was planned to produce 6 samples, but the beginning of the Soviet occupation in Estonia left them unfinished. After the 1940 occupation, the engine was removed, and the aircraft was used as target in an ammunition proving ground.

 

 

Description

PN-3 was of mixed design, a two-seat, dual-controlled, low-wing plane, with a steel tube fuselage skeleton covered by fabric. The aircraft's fuselage carcasse in the front of the aircraft, from the cockpit's first seat to the floor below the other one, was planked with aluminum panels. The self-supporting wing was completely wooden, and equipped with downward-opening safety spoilers.

 

Due to economic constraints, the prototype was built using a non-retractable landing gear with spatted wheels. Future planning foresaw a retractable landing gear.

 

Estonian Air Force placed a temporary solution for the prototype to equip it with a spare engine for a Hawker Hart biplane (water cooled 12-cylinder V-engine), which drove an innovative three-blade (Rotol or De Havilland, variable pitch?) metal propeller . The following construction of the aircraft was to be fitted with a modern 1,000 hp V-shaped engine.

 

The plane was extremely manoeuvrable. An altitude of 5,000 m was reached in 11.4 minutes. PN-3 was the fastest aircraft ever constructed in Estonia.

End of the Wikipedia text (also rearranged by me a bit).

 

Personal remark: From the given data (395 km/h at 4.000 m with an engine of 570 hp) I calculate a top speed of 476 km/h by using a 1,000 hp engine. The structurally equal Mitsubishi Ki-15 makes 480 km/h (also at 4,000 m), but it uses a powerplant of only 640 hp....

 

 

Finally, let's look at some pictures. My new version of XnView provides good results in sharpening now.

 

#1 (source: airwar.ru): The traditional sight. Made a bit bigger and lighter.

3836346435353338.jpg

 

#2 (source: forumwarthunder.com): Made a bit bigger and sharper. I think it looks especially good, I am bit proud of it:

3934386466313962.jpg

 

#3 (source: airwar.ru): The traditional drawing. Increased the background a bit.

3163313561386161.jpg

 

#4 (source: forumwarthunder.com): A very nice drawing! Increased the background a bit.

6230353065313033.jpg

 

#5: (source: lennusadam.eu): This interesting model hangs from the ceiling of the Estonian Seaplane Harbour building. Made smaller and lighter. No overwhelming quality still.

3538646530346434.jpg

 

 

Hope you enjoyed!

Best regards, RT


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#2 GregP

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Posted 30 July 2014 - 01:32 AM

Hi Holger!

 

I've been looking for info on the PN-3 for years. Thanks!

 

Any chance of a wing area? Or a few specs beyond the few usually available (which is almost nothing!)?



#3 Romantic Technofreak

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Posted 30 July 2014 - 06:08 AM

Hi Greg,

 

you're very welcome. I have no further information and shall ask Mr. Kitvel for some stuff. I let you and the forum know if I got something.

 

Regards, Holger (RT)



#4 Ricky

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Posted 05 August 2014 - 07:43 AM

Wow, a very good-looking and obscure aircraft! In some of the side views it is quite reminiscent of the Aircobra (particularly picture #2)



#5 Romantic Technofreak

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Posted 27 May 2016 - 03:47 PM

I received some data form Mr. Kitvel. Greg, look:

 

[Beginning of his original text]

Whatever there might be published about the PN-3, its measures which where given for two versions (either with the Rolls Royce Kestrel 480 PS, or Hispano Suiza 12 Ygirs 860 PS are the following ones:
weight 1840/2090 wings surface 22,5 m2, max speed near the ground level 340/410 km/h, flying in the height 4000 m max speed 395/490 (this is what she reached – 395); landing speed 102/109 km/h ; climb to 3000 m 4,8 min/2,6 min; climbing to 5000 m 7. 9 min/ 4,4 min; fuel and oil 300/500 kg , could reach 960 km with the speed 320 km/h and 1000 km doing 38o km/h - data for RR and HS.
take off 90 m/70 m, landing strip 136m/156 m. Length 9120, wing span 13000, height 2500. span (elevators) 3460.
All the real flights were done with Kestrel, data for the version with HS were the calculated ones.

[End of his original text]

 

Well, patience often pays! And thanks to Mr. Kitvel.

 

Regards, RT



#6 Armand

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Posted 27 May 2016 - 03:57 PM

.......... Length 9120, wing span 13000, height 2500. span (elevators) 3460.

Some might be disturbed by the large numbers, wich seemingly is mm's!
Converted to meters: 9,12M - 13M - 2,5M - 3,46M!

#7 GregP

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Posted 28 May 2016 - 03:47 AM

Wow RT, thanks! Been looking for these data from some 15 years and it shows up thanks to you.  I appreciate it.

 

I'm assuming the weight is kg. 

 

The speed is confusing. 410 kph is 254 mph, not 340. Or does that mean 340 kph down low and 410 kph up high? 

 

I had the span as 10.06 m, length as 9.00 m, height as 3.20 m, and didn't have the wing area. So I assume your measurements are in mm. I'll take your data since mine came from the internet, non-sourced references.

 

Again, thanks you! That's definitely worth a beer or two next time around, Holger.



#8 GregP

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Posted 28 May 2016 - 03:48 AM

It may LOOK like a P-39 a bit, but the engine is in front. So it didn't "tumble and roll and dig a big hole."



#9 flying kiwi

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Posted 28 May 2016 - 09:59 AM

 

The speed is confusing. 410 kph is 254 mph, not 340. Or does that mean 340 kph down low and 410 kph up high? 

 

I read it as being the speeds with the two different engines, both in km/hr. 


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#10 Romantic Technofreak

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Posted 29 May 2016 - 03:22 PM

Again, thanks you!

You're very welcome, Greg!

 

 

That's definitely worth a beer or two next time around, Holger.

Don't you think, for 22.5 m2 wing area I deserve 22.5 beer? :) :o

 

Best regards, RT






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