Re: Stukas and HMS Illustrious.
 

Hello
while trying without luck to find out info on the crunch and possible problems with the early one from Smith's Stuka book I noticed that according to the book R-2 didn't have the extra two 150 l fuel tanks inside outer wings like R-1, so R-2's internal fuel capacity was same as B-2s. So there were three max ranges, B-2, R-1 and R-2 all had different max range and if B-1's weaker engine was less thirsty than that of in B-2/R-2 then we had 4th max range.
And of those Stukas which attacked HMS Illustrious, those from I/StG 1 were Rs and those from II/StG 2 were Bs.

Juha

Re: Stukas and HMS Illustrious.
 

I offer the account given in Norman Friedman's British Carrier Aviation, which I think should be a fairly definitive source.

On 10th January there were eight hits:
1. 500lb bomb on S2 pom-pom
2. 1000lb bomb through port forward end of flight deck, bursting above the water outside the ship
3. 1000lb bomb through the aft lift exploding above the lift platform
4. 1000lb bomb through the flight deck on the centreline, exploding above the hangar deck
5. 500lb bomb on the edge of the aft lift, exploding high in the well
6. 1000lb bomb through P1 pompom, hit edge of armour deck but did not explode, did cause fire
7. 1000lb bomb near miss starboard side aft
8. 500lb bomb down aft liftwell.

On 16th January in Valetta harbour
Several near misses
9. 1000lb bomb through flight deck exploding in captain's day cabin
10. 1000lb bomb nearmiss on portside, causing 5 degree list due to smashed plating, cracking the port turbine feet.

I believe I've seen it written that the Luftwaffe carried 1000lb bombs, the Regia Aeronautica 500lb, but cannot quote a source. This would seem reasonable enough.

Re: Stukas and HMS Illustrious.
 

I guess Friedmans account is the same official one as cited by Brown. How reliable is it re. the bomb size. How did they distinguish between the effects of 500 kg AP and 250 kg SAP bombs? The size of the explosives should not be proportionate? (But it would have been far more embarrazing to have a 550lb bomb penetrate the deck armour than a 1000lb, which was actually a 1100lb bomb).

There must be some german account available, with hits credited to individual pilots, and bomb sizes given.

Juha;
Did the R-1 carry external drop tanks, (giving it max fuel of 1380 liters)? or were the droptanks maybe replacements in the R-2, increasing max fuel from 780 l. to 1080 l. rather than reducing it.

An order of battle for the Stuka groups for the invasions of Jugoslavia and Greece shows a mix of Bs and Rs in individual groups (e.g 9 Rs and 30 Bs). Do we know that II StG 2 and I StG 1 had uniform equipment in january?

I found a range figure for the Type 79Z radar carried by Illustrious. 90 miles at 20.000 feet. I reckon it means less at lower attitude, but is it proportional? (say 45 miles at 10000 feet, or 72 miles at 16000 feet?)

Csaba and Nick. With the bomb crutch being a standard item, why complicate the assembly process with two different types? Certainly the few kilos saved are hardly worth the problems. And if the "standard" crutch was not strong enough for the 500 kg bomb, how did they deal with the 1000 kg. bomb? Was it maybe dropped in level flight? Csaba; your post implies that at some stage, the standard crutch was strengthened. Do you know when? Would the planes operated in januar 1941 have had a uniform fit, or would the individual aircraft maybe have carried different versions, depending on age and sub-type. (was this maybe the limiting factor on ordnance carried by the Ju 87R-1, subsequently removed?)

Birgir Thorisson.

Re: Stukas and HMS Illustrious.
 

I just realized that my reference to Brown in the post above is incomprehensible, because it refers to a part of my previous post 3 that disappeared. To clarify, D.K. Brown (Nelson to Vanguard) cites the official report, but gives a different tally of hits elsewhere in his book.

Birgir Thorisson.

Re: Stukas and HMS Illustrious.
 

Birgir,

I don't know exactly, when the crutch was strenghtened, but the Dora definitely used the stronger one. Despite of this, there were crutch defects even with Doras, caused by SC 500 bombs (some of them were maybe cause by material failure, though).

Re: Stukas and HMS Illustrious.
 

Hello Birgir
R-1 could also use drop tanks and had longer max range than R-2.

On radar, radar ranges are bit problematic, it varied depending on target height but not linearly, at least those of USN air warning radars in 1944, say target could be "seen" from 75 mls if at 20000ft, from 76 mls but disappearing between 73 and 65 mls if at 17000ft and from 78 mls if at 15000ft and then the horizon was the determining factor, numbers are only to give the idea. Japanese were very skillful to utilize the height anomalies but those anomalies also gave a good indication of target height to good radar operators.

Did the gruppen had uniform equipment, my info that they had is from A. Price large article on Ju 87 in Feb 2005 Aeroplane Monthly, so I'm not absolutely sure that the info is correct. I'm pretty sure that 54 Ju 87s had just arrived on Sicily and 43 participied the 10 Jan attack against Illustrious, these numbers are given in Shores et al Malta Hurricane Years and in Smith's Ju 87 book.

IMHO the limiting factor for R-1 was more probably that with full fuel load the max permissible t/o weight didn't allow 500 kg bomb load.

Juha

Re: Stukas and HMS Illustrious.
 

Illustrious's flight deck had 3in armour, intended to protect against a 500lb SAP bomb. There does not seem to have been such a hit. There are more details of the armour coverage in Friedman. The lift was not protected. Only one of the bombs dropped on 10th penetrated the armoured deck, hit 4 - possibly hit 2 as well - with one other such hit on the 16th.

I don't know how they judged the matter, but they are likely to have been experienced in such matters. Discussions about damage to USS Franklin, on one of the warship sites (modelwarship.com, I think) quote a report which compared the size of the entry holes, rather than the damage. From memory, this was part of a discussion on whether one or two bombs had been dropped. One hole was determined to have been made by a rocket that "cooked off" in the fire.

Re: Stukas and HMS Illustrious.
 

Graham Boak;

I find the information given by Friedman (p.134) a bit confusing: It is a report of the relative qualities of 3.5, 3.0 and 2.5. inch thick armoured flight decks. 3.5in deck is supposedly proof against all 500 lb dive bombs, as well as 1000 lb AP bombs from 5500 feet (and lower). 2.5in is supposedly proof against all 500 lb bombs from 5000 ft and lower. The chosen 3in deck was proof against all 500 lb divebombs, as well as level bombs from 7000 ft. and lower.
But is the assumption valid that a bomb released in a dive has lower impact velocity than a bomb dropped from level flight?
If the RN in 1935 was thinking in terms of Swordfish type "dive bomber", described somewhere as "floating gently downwards" and in no need of airbrakes, they would be seriously underestimating the impact velocity achieved by monoplanes like the Stuka and SBD.
This, along with the 10 % greater weight of the German 250 kg bomb, makes me unsure if the Illustrious´ armored deck was in fact proof against the 250 kg SAP bomb.

Juha.
I was just reading the account in "Air War for Yugoslavia, Greece, and Crete", about the attack by II. StG 2 on Formidable. It seems to imply a serious failure of radar warning. The Stuka Gruppe was out searching for supply ships for Tobruk when they stumbled upon the main force of the Mediterranean fleet, and the account (rather unclear) is that first one staffel, and later the others found and bombed the Formidable, without being intercepted by Fulmars. There was no TB ruse, as with the Illustrious. For that to happen, the radar warning system must have been very much "at sea", weather it was because of human errors by the radar operators, or if there were serious technical gaps in the coverage that the germans just happened upon.

Birgir Thorisson.

Re: Stukas and HMS Illustrious.
 

Don't expect too much from wartime radar. Coverage was not 100% at all altitudes, but the transmission produced a number of lobes. Detection would be good for the quoted distances inside the lobes, but aircraft at the correct altitude could get close to the fleet without being detected. The Japanese are known to have made use of this in their attacks on the USN.

It is perhaps an open question whether ay this stage the Germans would have been aware of this as a technique, but it could well have worked to their benefit by chance.

Re: Stukas and HMS Illustrious.
 

Hello Birgir
Quote:"But is the assumption valid that a bomb released in a dive has lower impact velocity than a bomb dropped from level flight?"

To my understandig the assumption is valid, bomb is more solid than a/c, so it has more mass per given frontage so it accelerates better. And to increase even more the difference in acceleration, bomb doesn't have dive brakes.

Juha