Romanian aircraft board instrument???

Hi! I need your help about one Romanian aircraft board instrument. Can you please identify it, on what aircraft was it used?

It is made by Prerom, I read that the factory produced aircraft parts during the WW2. But did it work postwar with the same name? Is this instrument WW2 or later? Thank you very much in advance!







This post has been edited by Theodor on November 01, 2007 08:54 am

Hi Theodor,
This is a very nice instrument. It is an Airspeed Indicator, or Vitezometru in Romanian, and it measures the speed of an aircraft. This one is calibrated in kilometers per hour and because of its upper indicated speed of 700 km/hr may well have come from a fighter. It is very similar to the ones fitted to IAR 80s. Unfortunately I have no idea about its age or ww2 use.

The 2 connections on the back are inputs for static pressure, outside air pressure, and dynamic pressure, which is the pressure caused by the aircraft moving through the air. By comparing the 2 the instrument can give an indicated airspeed.

Hope this helps. Nice find!

Colin

This post has been edited by Stratton on November 01, 2007 11:43 am

Thanks Stratton! This is exactly what I thought - at a speed of 700, this must bea fighter. The IAR fighters had top speed of over 500 km if remember right, so I guess a 700 km speed instrument would be just right. If it is not postwar, of course...

Hi Theodor and Stratton,

Yes it is an "Vitezometru" a standard gauge used on different types of planes made at IAR Brasov. It could be from a IAR 80-81 but most probably came from a slow speed aircraft like Fleet biplane or IAR 27. You can see that it is modified and added (written by hand) nr 180 (between 150 and 200). It could mean that cruising speed is 180Km/h.

The company "Prerom" Brasov was created in 1935 by a joint with a czech company "Prema". Probably the production of aircraft gauges stopped after the WWII ended ( IAR Brasov also stopped the aircraft production)

Thanks Cantacuzino,
Thats sounds like a very probable origin for this gauge. Interestingly though, as Im collecting reference pictures for the IAR 80 series, I have found a wartime picture of an IAR 80/81 cockpit showing a similar gauge with what could be the same added numbers. Perhaps this could have been an approach speed for the fighters, or a flap limit speed , but as you know Im only guessing.

I will attempt to post the picture, but may have to e-mail it to you and Theodor.

Colin

http://img68.imageshack.us/img68/5057/009gen9.jpg

I must admit its barely visible, but it does look like there is something added on the face in exactly the same position.

I am just trying to find where this picture came from, somewhere on Forum RHC.ro I believe, but will post full picture credit as soon as I can find it.

Colin

This post has been edited by Stratton on November 01, 2007 07:17 pm

Thank you very much for the response, Cantacuzino! The 180 is just smaller, but it is written the same way as the other indications and also glows in the dark, like all else. And indeed it must be the cruising speed of some not fast machine. Interesting, how this ended in Bulgaria. Maybe the Prerom supplied instruments for some types of Bulgarian aircraft? /the engines, instruments and some other things had to be imported, as there was no local manufacture/. Just guessing about that.

It's known that the Bulgarian fighters, damaged during the air struggles with USAAF were repaired exactly in Romania. Maybe this is the "source" of this indicator

That's correct, but only Bf 109s were repaired in Rumania, at ASAM-Pipera, near Bucharest.

Gen. Dénes

P.S. Hello Theodor! Nice to see you here, too!

I belive that 180 marking could be the optimum takeoff/landing speed. That speed varies from aircraft to another, depending on the aircraft weight and portance( engine speed) . For ex,( afaik) the 109`s have the optimum speed for takeoff of 150 km/h

I am curious if that "PREROM" manufacturer is what later becamed "Electroprecizia" Sacele. If my memory is good, Sacele is at 27 km from Brasov. (If I am wrong, it is at 9 km from Brasov. ) During the Communist era, "Electroprecizia" manufactured alternators (synchronous claw-pole generators) and starters (DC series wound electric motors) for the Romanian automobiles Dacia 1300, Olcit and ARO.

As my graduation project for the title of engineer was the theory and construction of synchronous claw-pole machine, I traveled twice to "Electroprecizia". First time it was just 3 weeks before Ceausescu got his well deserved "happy end".
There I learned that they started their existence in the 1930's, as a manufacturer of control and measurement apparatuses instaled in the Romanian airplanes, like the famous IAR-80.

It is possible that in the 1980's they may still have blue prints from what they did in the 1930's. As things were changing fast in Romania of today, I don't know if the factory is still functioning.

This post has been edited by Florin on January 04, 2008 01:18 am

...In 2 words, a Pitot tube

The Pitot tube was good for the speeds of the planes with piston engines. It is not useful for higher speeds. But of course the apparatus shown here was used in an old style plane. The manufacturer chose as company symbol a propeller!

This post has been edited by Florin on January 04, 2008 01:28 am

Yes, PREROM is what later became Electroprecizia. See here:
http://www.electroprecizia.ro/istoric.php

Few clarifications:

One port is indeed the static pressure port. The second is the Pitot pressure port. As can be seen also in the picture, the ports are labeled S for Static and P for Pitot. The working principle of a Pitot speed indicator system is described in any basic Physics manual. I'll only mention here that the Pitot pressure is a sum of static and dynamic pressure. The dynamic pressure is the result of the respective body (such as an aircraft) movement. In the indicator, the static pressure is subtracted from the Pitot pressure and the resultant is applied to a mechanism that rotates the indicator arm against a scale calibrated in speed units.

Maybe the author of the quoted statement above meant the same, but the reference to both "static pressure" and "outsude air pressure " creates some confusion.

Not true. The Pitot tube is good not only for planes with piston engines; it's "good" also for any aircraft and even gor glider/sailplane (no engine at all). It is quite useful at higher speeds as well. Any atmospheric flying body that generates lift from the interaction between the airflow and a material surface has at least one Pitot.

It is not a known practice to mark the cruising speed or take-off/landing speed on an ASI (airspeed indicator). The "180" indication is rather a stall speed, most likely in clean (no flap deployed) indication.

Sorin

Hi everybody!
At National Romanian Archives from Brasov District (located in Brasov, George Baritiu street no.34) exists the documents fond "Prerom Sacele" (indexed IV 53) that contains a lot of technical documents about aircraft instruments produced during 1937-1948.
There are many things that might be interesting.
Regards,