IAR-80 with german inlines

mack8

Airman
29
31
Jan 4, 2023
Wanted to post something like this for a long time.

So in OTL there were various projects to use a Jumo-211 on it (during the design phase), or a DB-601Aa or 605A both of which were tested in 1941 (failure, severe airframe vibration, probably because the airframe needed streghtening to cater for the power of the 601) and 1943 respectively (quite sucessfully this time, unfortunately no performance data has survived, of course i would sell my soul to the devil to ever see such data!). But as far as DB engines go, apparently it couldn't have been possible anyway as the germans had none to spare.

So that leaves the Jumo-211D and F, which Romania bought for the JRS-79, apparently 210 engines in total. But also recall that the germans actually had an overproduction of Jumo-211 in 1942-43 i believe, resulting in several thousands of engines sitting in depots unused! (between 3000 and 4000?)

Back at the design stage in 1937, apparently they wanted to use a Jumo-211 both for IAR-80 and the Savoia S79Bs ordered by Romania, but things are confused because what i read refers to the 211Da, which i'm pretty sure was not even existing in 1937. I would think it would have been a Jumo-211A? Perhaps later on they switched to the 211Da when that became available.

Anyway the comparison i saw refer to the Jumo-211Da which is stated to have 930HP at 5700m and IAR K14 1000A of 1000 HP at 4000m (which may be an alternative designation for the IAR K14 IV C32, like i said things are confused). The speed estimated was 528 kph at 4000m with the IAR engine and 558kph at 5700 with the Jumo, a 30kph increase. Weirdly the weights quoted refer to the prototype, with the Jumo-211 being heavier, empty 1780/1845 kg and maximum 2280/2470 kg, so about 200kg heavier with the Jumo. Length was increased from 8,16m to 8,85

The maximum performance report i see for IAR-80 Nr 2 measured in 1940 likely with a fully rated engine at 850mm Hg, show 524kph at 5350m, weight 2648kg. So extrapolating, using a Jumo-211Da would increse weight to about 2850kg and increase speed to about 550kph at probably 5700m, am i in the ballpark here?

Series production IAR-80s were increasingly heavier, for example according to one article in MOdelism magazine the first series was 2720kg full and 514 kph speed but i think at 4500m, the IAR-80B was 2810kg and 495kph with span increased to 11m from 10,52m , while the later IAR-81C was 2900kg in fighter configuration and speed dropped to either 470 (Modelism) or 485kph, but again things are confused, some recent books just put that 485kph figure across the board for all variants which is not right due to weight and span differences. So the earlier figures i find much more accurate and plausible.

So let's suppose the germans give Romania some more Jumo-211D and Fs to also equip most or all IAR-80s. You guys who know this stuff much better than i do, what kind of speed performance should be expected with a Jumo-211F? How about for a DB-605A or DB-601A? I have read of the torque problems of the S-199 that used stock engines, but perhaps they could change the prop reduction gear ratio for a fighter application? The IAR-80 has a wide track landing gear anyway so the torque may not be such a problem.

Here is a link to a discussion topic where a very talented guy, Asgard, made some drawings of how a Jumo-211D or DB-601A powered IAR-80 would look like, which i find gorgeous. I guess for a Jumo-211F or DB-605A the cowling must be different, perhaps more like the one used on the JRS79B1, but it's just guessing at the moment.

 

tomo pauk

Creator of Interesting Threads
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Apr 3, 2008
IAR-80 seems like a reasonably streamlined A/C, with a small wing. Probably very close to the J.22 wrt. size and drag?
Provided the installation of the Jumo 211D is done with an emphasis on as seamless retrofit as possible (narrow fuselage can help a lot), we's probably get something in ballpark of the D.520/Bf 109E, speed-wise?
 

mack8

Airman
29
31
Jan 4, 2023
Well that roughly 550 kph potential figure could put it close to the 109E, plus better altitude performance compared to regular radial variant, better in a dive and zero G maneuvers, probably better climb too? Would a DB-601A give a bit more speed compared to the Jumo-211Da?

The single existing picture of the inline prototype, and the drawings plus the crossection of the fuselage seems to show that it was quite well tailored for an inline, probably because initially was designed for the Jumo?

What do you think the ballpark speed would be with a Jumo-211F or DB-605A? Would there be another 20-30 extra kph, more, less? Probably the weight would be about 3100-3200kg, which is roughly similar to a standard Bf-109G?
 

tomo pauk

Creator of Interesting Threads
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Apr 3, 2008
Well that roughly 550 kph potential figure could put it close to the 109E, plus better altitude performance compared to regular radial variant, better in a dive and zero G maneuvers, probably better climb too? Would a DB-601A give a bit more speed compared to the Jumo-211Da?
DB 605A will make more power, even in it's down-rated form, roughly 1/3rd more. Well over 600 km/h for the such powered IAR-80.

What do you think the ballpark speed would be with a Jumo-211F or DB-605A? Would there be another 20-30 extra kph, more, less? Probably the weight would be about 3100-3200kg, which is roughly similar to a standard Bf-109G?

There is no doubt that weight will be greater than the original. How much greater - probably ballpark of the MC.202-205, depending on extras, like guns etc.
The 211F will give another 10-15% more over the 211D - somewhat under 600 km/h?
 

tomo pauk

Creator of Interesting Threads
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Apr 3, 2008
M mack8 - could you provide some ... non-Wikipedia info about the Romanian experiences with the 13.2mm HMGs by FN, as used on the IAR-80s?
 

BarnOwlLover

Airman 1st Class
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Nov 3, 2022
I found this on secretprojects, with both speculative and real photos and illustrations:

 

mack8

Airman
29
31
Jan 4, 2023
I found this on secretprojects, with both speculative and real photos and illustrations:

That is my own topic from ages ago, but thanks for finding it:)
 

mack8

Airman
29
31
Jan 4, 2023
M mack8 - could you provide some ... non-Wikipedia info about the Romanian experiences with the 13.2mm HMGs by FN, as used on the IAR-80s?
Hi Tomo,

I can't say i have much useful info to add, as i understand those HMGs were first installed as defensive weapons on the romanian JRS79Bs and possibly the earlier S79Bs but not sure about the latter, i will have to re-check. Then as the IAR-80 badly needed an increase in firepower after 1941, they were taken off and installed in the IAR-80B and IAR-81A. Rpg was 150 and 175 respectively (which seems quite low), likely as an interim measure until the 20mm cannons arrived.

I don't remember reading if they were appreciated or not, though probably they were found insuficiently powerful to deal with the american heavies B-17/B-24, later IAR-80/81 had either 20mm Ikarias or MG151/20s.

If you have some specific questions i can look in the IAR-80 books i have to see if there's anything useful.
 

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