A straight technical approach to IAR 80, Mytha and reality

Here you are.



Gen. Dénes

Thank you Denes
C Glijinski

Another picture of Cpt.Vizanty near his IAR 81 C no 344 (with this mount he was credited with 2 P38 shot on 10 june '44)

Thanks a lot! You made my day!
Looks like a great couple.
CG

There is K14 on display in the National Military Museum. Does anyone have any photos of it or do we have to go there and take some?

I had some pics of the K14 in the Military Museum, unfortunatelly I do not know exactly where they are and I am due to leave for airport soon.
Glijinski you sure got my interest, can't wait to get back and start working with you

Some data for the engine IAR-1000 A1 (source Constantin C.Gheorghiu -Fabricile de avioane romanesti in perioada interbelica)

-bore/stroke: 146/165mm
-cilinder vol. : 38,6888 l
-compression ratio : 6,14
- power : 1140 Hp at (atm. pressure) 935 mmHg and 1040Hp at 850 mmHg. The data are calculated using CINA standard with zero dynamic pressure on the stick.
- Specific weight: 0,675 kg/Hp

Materials used:
pistons: RR-56 light aluminum alloy
cilinders liners: Mn-Si alloy
conecting roads: Cr-Ni alloy
Crankshaft: Cr-Ni-Mn alloy
valves were filled inside with Sodium (for easy heat transfer)

Other data:
Carburetor type Zenith
Manual and electric starter type IAR (Eclipse licence)
2 magneto type Bosch
2 spark plugs on each cilinder.
Compressor boosting to 3600m altitude

This post has been edited by Cantacuzino on March 01, 2008 05:24 pm

I made pictures but at Leonida technical museum.

For some technical drawings and pictures with IAR 80-81 try this link

http://www.cartula.ro/index.php?option=com...g2_itemId=15536

Greetings Gents.

Thank you for the information. Over the weekend I dug some useful information from cyberspace. At the first view the engine can not have too many differences over the original license Gnome-Rhone. It will be very helpful if someone can correlate the G-R versions with the IAR versions (the identification code of the engines). Also there is a lot of information on several other WW2 forums which I can not retrieve without registration. I wonder if someone else is already a member and can obtain it. There is a plethora of airplanes using engines from the same G-R family (German, Italian, French, Japanese, Russian, Polish, Finish, etc) and very useful information might be available. As en example, the con-rod length (which is still missing) is unlikely to be different (anyway, small variations are not fundamental). I still need with high priority any information about valves and spark timing. Also gasoline octane number (probably 87) and engine RPM at maximum power (should be in the same book mentioned by Cantacuzino ) Other than that, for a first simulation we are good. Talking about books, I asked about relevant technical literature and the single important title offered to me was ZINNER “Supercharging of Internal Combusting Engines” Springer Berlin, a very old book mainly about WW2 aviation engines. I am not sure if the G-R family is included in this book but I’ll find in a couple of days. Also, if you know any other relevant titles, please let me know.
In Cantacuzino’s data I found two (unknown to me) issues. First is saying that “The data are calculated using CINA standard pressure on the stick”. I don’t have any idea what CINA standard means ( “stick” should be Pitot tube). Also the last line is saying “Compressor boosting to 3600m altitude” and my interpretation is 760 mmHg manifold pressure at this attitude (no boost). I’ll appreciate if someone can clarify these issues.

D-13-th Mytzu, if I may ask, how many millions points can you run in a decent time? And how trustable is your software e.g. FLUENT, CFDesign, in house developed, etc?

DATA STILL MISSING

Engine rpm at max power
Gasoline octane number (probably 87)
Con-rod length
Timing

Thank you in advance,
CGlijinski

D13-th_Mytzu could help you with better translation of technical data from Dan Antoniu and George Cicos book.

I will try but I'm not specialist like him with this kind of stuff

IAR-14 K IV c32 1000A1 engine technical data:

-Propeller sense of rotation: Counterclockwise (view from cockpit)
-Reduction gear: 2/3
-Omologation Altitude: 3200m
-Boosting pressure (admission pressure?) at omologated altitude (3200m) : 850mmHg
-Nominal power at 3200m with 2300 RPM : 1000Hp
-Maxim power at cruising speed : 960 Hp
-Nominal power at ground: 880Hp
-Nominal propeller rotation: 1533 RPM
-Maxim propeller rotation allowed: 2420 RPM
-Cilinders numbers: 14
- Engine config.: radial
-Bore:146mm
-Stroke:165mm
-Cilinders vol.: 38.67 l
-Carburator: Zenith NAR 130 RGSL
-Oil consumption: 10gr/Hp hour.
-Magnetos: 2 x Bosch GE 14L11
-Spark plugs: 28x Bosch DM 175ET6
-Total weight: 705,170Kg
-Overall diam.: 1264mm
-Length: 1844mm

This post has been edited by Cantacuzino on March 04, 2008 03:13 am

Engine rpm at max power: 2300 RPM for 1000Hp
Gasoline octane number : 87
For Con-rod lenght i have an aprox 1/5 drawing. Possible to calculate (with aprox) using engine bore (146mm) as reference. I measured (on the drawing) and cilinder bore is 43mm and con-rod length between axis is 89,5mm.

For timing i have only 1/5 Timing gear technical drawing (no data).

CINA is an abreviation. I don't know the meaning (Could mean something like NASA )
" stick" it's not pitot tube it's the control stick (in romanian mansa)

Compressor boosting to 3600m. It mean to have the max engine power, compressor help boosting ( 850mmHg admission pressure) up to 3600m.

Single stage compressor was one of the main reason the IAR 80-81 could not perform well after 7000m compare with Mustang P-51 (with double stage compressor).

Also you can see the climbing rate at different altitude:

500m....0'07"
1000m....0'34"
2000m....1'26"
3000m....2'32"
4000m....3'30"
5000m....4'40"
6000m....6'06"

Gentlemen,
We are in real progress. With Cantacuzino’s help the con-rod length is revealed to be roughly 300 mm (304). What about the con-rod main bearing? I found some good info here http://caea.free.fr/fr/coll/gr14k.html where is mentioned that the crankshaft is made from two bolted parts and HAS rolling bearings. Is not clear for me if this solution was maintained by IAR (might not work at a higher power) and if the con-rod has also a rolling bearing or not. The drawings should be very explicit. Please confirm/infirm. (A rolling bearing mechanism is more efficient and can save up to 5% from the total power, aprox. 50 hp in our case)
Information still missing:

Valve timing
Spark timing (advance)

The typical info I am looking for valve timing looks like this (example only):

I: 30 BTDC - 70 ABDC
E: 50 BBDC – 25 ATDC

This means that the inlet valves opens at 30 degrees Before Top Dead Center (BTDC) and closes at 70 degrees After Bottom Dead Center (ABDC). This info should be somewhere in the same book or manuals, however BTDC, ABDC, etc might have different letters according the Romanian/French language but should have similar meanings (e.g . BTDC in French should be APMS - Avant Point Mort Superior but I am not 100% sure)

Spark timing is a different issue but is also an angle. Might be (example only) 7 degrees at idling at 25 degrees at full power and rpm. Or should come with a correction curve according boost and rpm (some old planes had the spark timing controlled manual by the pilot). If there are 2 spark plugs per cylinder, typically EACH spark plug has a different timing obtained by slightly different phases for the 2 magnetos (angular mechanical offset counting for few milliseconds).
This info might be available somehow hidden in the manuals e.g. the magneto tuning/mounting procedure or magneto marks, etc The timing in general and twin spark timming in special are important antiknock countermeasures. Therefore info might be found in relation with knocking e.g. modification needed to operate with a lower octane number
Thank you,
CG

This post has been edited by Glijinski on March 04, 2008 07:44 pm

I confirm (from drawings) that crankshaft is made of two bolted parts and has 2 rolling bearings and 1 ball bearing (at shaft nose). The con-rods has only bushing bearing.

This post has been edited by Cantacuzino on March 04, 2008 08:45 pm