Aircraft Modifications

[Shortround6]

You might be able to fit it in but the 37mm COW cannon (which did NOT become the Vickers' S without a LOT of development/modification) wasn't that HOT of a cannon.

It used a lighter shell at a lower muzzle velocity than the "S" for about 60% of the muzzle energy of the S (depending on ammo) and fired slower, not that the S was any great shakes in the rate of fire area to begin with. The COW was feed with 5 round clips which might have been extended.

Video of a COW firing: skip to 0.46 if you want.

[video]http://video.search.yahoo.com/video/play;_ylt=A2KLqIDB1KxReBgAUPH7w8QF;_ylu=X3oDMTBrc3 VyamVwBHNlYwNzcgRzbGsDdmlkBHZ0aWQD?p=37mm+COW+cann on&vid=5b2caef8ee3659be2873f23ab410b5bd&l=1%3A29&turl=http%3A%2F%2Fts1.mm.bing.net%2Fth%3Fid%3DV.46 35439006549468%26pid%3D15.1&rurl=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DRz 1MSHglGP4&tit=C.O.W.+37mm+cannon+fitted+to+Blackburn+Perth+f lying+boat&c=0&sigr=11au2isnj&age=0&hsimp=yhs-01&hspart=mcafee&type=mcafee&tt=b[/video]

Notice the recoil and movement of the gun in this mount?

A couple of MGs would do better for flak suppression.

 

[tomo pauk]

A favorite plane modification of mine would be the A-36 with Vickers S cannon, the 'S' being outfitted with Littlejohn adapter. Ditch the wing MGs prior that.

 

[merlin]

I like the idea, but you might need that position on a plane that big to help drop the torpedo's. Also, I don't know if structural integrity could support such a gun at the front, but more knowledgeable people would have to comment on that.

My thought there - was the bomb aimer is not necessary - the pilot can do that. In that the bomb aimer looks down to drop bombs, you don't look down when torpedo dropping, but line the plane to drop in the direction you expect the target to be.
I had the idea that the armourers at an experimental Squadron comes across the cannon seemingly abandoned and forgotten, and try an installation on some aircraft giving some enemy ships a surprise!!


Shortround6: thanks for the info and video clip. I assumed with such a weapon - its effective range would be greater than MGs, and besides the Wellington would still have the two 0.303" in the front turret.

 

[Shortround6]

If you are torpedo bombing the nose of the plane is pointed ahead of the ship (unless it is a really slow ship). torpedo is dropped on a collision course with the ship. Fixed guns don't do a lot of good for AA suppression on torpedo bombers until AFTER the torpedo is dropped at which point the pilots concentration SHOULD be on getting out of there.

 

[MacArther]

If you are torpedo bombing the nose of the plane is pointed ahead of the ship (unless it is a really slow ship). torpedo is dropped on a collision course with the ship. Fixed guns don't do a lot of good for AA suppression on torpedo bombers until AFTER the torpedo is dropped at which point the pilots concentration SHOULD be on getting out of there.

Agreed! If you are going to do a straight at pass at a ship, there are bombers better suited to skip bombing or mast-top bombing styles.

 

[Boa]

I would like to modify the Yak-3, making the Klimov VK-107 more reliable, putting the exhaustvalves on the outside, making the supercharger more effective at all altitudes. A more effective wing with a more laminar flow and highspeed flaps and slats. I want 3 20mm guns, Hispano Mk. Vs.
I think I want the Cockpitheater to give a more even heat to the pilot, at a 21* celsius. And a cooling box with icecream, vanilla... And beer... a friendly stewardess... and.. and... *

This is BOAs mom... Please, please dont let him make wishes on aircrafts, his brain just cant cope with it.
Now he is here on the floor, drooling.
Thanks a lot..
//
BOAs mom

 

[Civettone]

I would modify the Ambrosini SAI.403. It was an Italian wooden fighter. Taken into production but probably none served before the Armistice. It had a 770 hp air cooled engine, which gave it an amazing maximum speed of 640 kmh. It lacked a bit in climb rate and also its engine was single stage, plus a light armament and armour made it unsuited for high-altitude bomber interceptions. It could however be turned into an excellent dogfighter. A major problem was its light armament: it carried two Breda-SAFAT HMGs and two Mauser cannons. The SAFATs weighed 27 kgs and the MG 151s 42 kgs. These could have been replaced by 4 MG 131s, each weighing 17 kgs, giving it a similar armament as the P-51B/C. Hereby saving 70 kgs of weight.
Also possible would be to use the Hispano-Suiza 12Y engine. This produced around 950 hp and weight (dry) only 50 kgs more. CoG would be okay because the Hispano Suiza was much shorter than the Italian engine. Plus, it could get a cannon firing through the propellor hub. With the 20% added engine power, its maximum speed would be around 660-670 kmh? And also climb rate would be improved.

So you would have a wooden fighter, with a speed of at least 660 kmh, 1 MK and 2-4 HMGs ... sounds like an Italian Yak-3 to me

In fact, Ambrosini was working on the SAI.503, which would have received the air-cooled IF Zeta engine or maybe the DB 605.
Kris

 

[Dogwalker]

Really the 403 was equipped with an Isotta Fraschini Delta IV RC.17/50 (the same was used in one the SAI 207 pre production aircrafts, the MM8433), the same used in the Caproni Ca.331b Raffica. It was the last developement of the Delta, with a two speed supercharger, 870ps at takeoff, and 850ps at 5000m.
The prestations indicated for the 403 were those projected, however, we know that the SAI.207 obtained 580 km/h at 4500m with the Delta III RC.40, 750ps at 4000m, so, the 403 could reach, at best, 604km/h for the adjunctive power alone, plus something for the higher critical alitude, plus (likely) something for the different airfoil, less something for the larger wing surface.
A shame the Zeta was never fully operational, as a Zeta engined 207/403 would reach about 680 km/h (without taking into account the larger frontal surface of the Zeta, and the higer critical altitude of the Zeta RC.27/60)

 

[Civettone]

DW, is 604 kmh a typo? Did you mean 640 ?

The SAI.403 had other aerodynamical refinements which added to max speed.

I think the Zeta would require a new airframe alltogether. The Zeta was essentially a double Delta, thus quite heavy!
If the Italians had managed to make it reliable and deliver 1,500 hp, it would have been their perfect engine, suited for all their fighters and bombers.

Kris

 

[Dogwalker]

No, I mean 604 km/h for the adjunctive power alone, to which we have to add something for the higher critical altitude (850ps at 5000m, vs 750ps at 4000m), something (likely) for the more refined airfoil, but something less for the larger wing surface. To me, a realistic maximum speed for the 403 is from 615 to 620 km/h at about 5500m. The SAI 207 and 403 were aerodinamically very similar, it is unlikely that ing. Ambrosini has been able to do miracles from one to the other. And we can already say that Ambrosini and Stefanutti have really made miracles. Those performances are however comparable to those of a "5 series" fighter, with 500ps less.
The Zeta was not a double Delta, but a double Gamma (smaller and lighter than the Delta: 19.2l, 420kg, and the duplication of the cylinders obviously didn't duplicate the weight, since the crankcase was the same). The double Delta was the projected 1600hp Sigma. Don't know the actual weight of the Zeta, but Zeta engined Breda 201 was projected to weight 100kg more than the DB601 engined one. An higher weight adequate with the higher power and critical altitude.
The Zeta already would be a great engine. It's true that its power was less than that of a DB605A/RA.1050, but there wasn't the additional drag of the radiator.

 

[Civettone]

I don't know if these drawing are accurate but they indicate that the design was much altered. The SAI.207 had more of a triangular cross section and the .403 a rounded one. Also the tail wheel was retractable. Is the 640 kmh figure not an official number? The aircraft was built and tested by both Italians and Germans. No data known?
I also wonder if the critical altitude shift from 4,000 to 5,000 m was not more decisive? I am not an aeronautical engineer but I do know that two-speed superchargers add a lot of maximum speed higher up.

Good call on the double Gamma, I was never sure which version was true. The Zeta delivered 1,250 hp but this seems to have been below what was expected. The Zeta was expected to get up to 1,500 hp. That made me believe it must have been a double Zeta. A 1,250 hp engine is of course not going to do be worth much, compared to the existing DB 601 aka RA.1000.

I remember seeing the Re.2001 with the Delta engine and it had a large air intake, I assume the Zeta would require one even bigger to cool it properly.
Kris

 

[Dogwalker]

Those drawings are artistic impressions (as it's easy to say confronting the two cockpits. Or that of the 403 is too large, or that of the 207 is too small). Little differencies in the shape of the fuselage of the two aircrafts exist, but the SAI 207/403 was really hidden behind its engine (so the triangular cross-section) and a pair of MGs' barrel over it. Having the Delta III and IV the same shape and dimensions, the 403 could have a different cross section only increasing the frontal surface. As you can see in those pictures, there are little differencies in the cross ection of the aft part of the fuselage (apart from the obvious differences in control surfaces), but these can lead only to marginal differences in performance. The aerodinamic of the SAI 207 was already extremely efficient, and it is very difficult to improve much something already extreme.
The 640 km/h is official, in the sense that was estimated by the manufacturer. Unfortunately the test data did not survive to the war.
The effects of the different critical altitude (1000m) can be estimated from 10 to 20km/h (Gianni Cattaneo, while being very critical of the project in general, estimate it in 20 km/h), but do not forget the larger wings and two cannons.

The Ra.1000 gave 1050ps at 4100m. The Zeta Rc25/60 had the critical altitude at 6000m. At that height was more powerful than a DB601E, and a little less powerful than a DB605A, but without the drag of the radiator. In fact, the Caproni Vizzola F6Z was faster than the DB605 engined F6M.

Here you can see the air intake of the Zeta (below is the oil radiator), at the time of it's homologation.

On the F6Z, with Alfa Romeo propellers.

 

[Civettone]

Very interesting stuff!

You mentioned the DB 601E. I assume that was again not a typo. Have you ever read anything about Alfa Romeo or any other company trying to upgrade their DB 601Aa to the DB 601E? It also remarkable that the DB 605 was licence produced not to AR, but to Fiat. I assume Fiat had to learn from scratch how to build these engines while AR could have switched production. Of course, AR engine works would have to be enlarged or been given control over other factories.
Also, I have read that the DB 603 was going to be licence produced. Then again, I read a lot of rumours. I have read the Ca.313, CA.331, SAI.403 and AR.135 engine being ordered by the Germans, Kurt Tank examining the Fiat G.55 for production, etc. All seems to come from Italian publications without any evidence in non-Italian sources. Drives me crazy :/

Kris

 

[wuzak]

What was the bore stroke of the IF Zeta?

 

[altsym]

According to an article by David Shepherd, 160mm stroke, 132mm bore.

 

[wuzak]

So the Zeta produced roughly 1/2 horspower per cubic inch.

With 132mm bore and 160mm stroke the capacity is 52.55l or 2545 cubic inches.

 

[Dogwalker]

Have you ever read anything about Alfa Romeo or any other company trying to upgrade their DB 601Aa to the DB 601E?

Anything. After the DB601, the goal was to produce the DB605.

It also remarkable that the DB 605 was licence produced not to AR, but to Fiat. I assume Fiat had to learn from scratch how to build these engines while AR could have switched production.

The engine was called FIAT RA.1050, but has to be produced by Fiat (5000 ordered), Alfa Romeo (750 ordered) Isotta Fraschini (3000 ordered) and OMIR (1000 ordered). Isotta Fraschini and OMIR had not the time to set the production, and Alfa Romeo, still in 1943, had problems in building enough engines to replace the existings Ra.1000 (whose expected life was of about 60 hours of flight only. See, for example, the difficulties for IMAM to have a pair of engines for the RO.58 prototype), so the engine, in the end, was produced only by Fiat.

 

[vinnye]

I would think it was a bad idea, slower rate of fire, less ammo carried, weight penalty - structural reinforcement etc.

 

[wuzak]

I would think it was a bad idea, slower rate of fire, less ammo carried, weight penalty - structural reinforcement etc.

Posted in the wrong thread?

 

[Civettone]

Must be ...


Kris