Bomber Range with Bombload?
- Thread starter Wargames
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Francoquarter
New Member
This is not true, however the internal load not reduce significantly the range if not get down the fuel load
That makes sense but the problem I'm encountering is Sm.79's in Libya could only reach Alexandria, Egypt with half bomb loads. My source gives the Sm.79 range as able to travel 1,620 km (1,000 miles) with a full bombload:
https://military-history.fandom.com/wiki/Savoia-Marchetti_SM.79
This seems consistent with other sources which give even more range with an equal or smaller bombload. However, Derna to Alexandria is well within 1,620 km. That produced my question. The range given by sources appears to be overstated.
https://military-history.fandom.com/wiki/Savoia-Marchetti_SM.79
This seems consistent with other sources which give even more range with an equal or smaller bombload. However, Derna to Alexandria is well within 1,620 km. That produced my question. The range given by sources appears to be overstated.
Francoquarter
New Member
Actually the full load range, as the manual, for the SM 79 with Alfa 126 engines, is 1820 km at 380 km/h, take in the count that that probably the bomber going to Alexandria are not flying over the land so the actual route is longer, the aircraft not fly at the engine regime like a peace time range trial and the formation and obviously the reserve. i've not capable to find a calculator with Derna airport but from Benina airport are 904 km and this with a over land route, so i don't see nothing strange
ps add the hot clime give less power so for same power more fuel need
ps add the hot clime give less power so for same power more fuel need
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Don't tell me you believe the ranges given in a book or wiki for any bomber of any nation are real values...you have to get the operational documents, not factory or lazy historians. 
For a start you need to get weights.
These are operational numbers:
BR.20 1795km 325kph(5000m) 1000kg bombs 1800kg fuel 150kg oil 340kg crew 54kg guns 72kg ammunition, 180kg radio, 16kg foto, 8kg others. 6693kg empty. Total 10313kg.
S.79 1845km 360kph(5000m) 1000kg bombs 1770kg fuel
Z.1007bis 1795km 368kph(5000m) 900kg bombs 2230kg fuel
Now there are other considerations, what would be the mission altitude, range backup, wind for or against?, weather, route? how much time at maximum speed/power? finally aircraft condition and crew training. And crew quantity. For example the crew for S.79 above is 4 =340kg but S.79 operated often with 5 and sometimes even 6 when with naval observer.
Another, some bombs are not really their nominal weight. The Italian 250kg bomb is 259kg and 100kg SAP bomb is 109kg, the ASW 160kg bomb is 178kg, 500kg bomb is 508kg and the 800kg bomb is 822kg
Edit: a large raid also means first aircraft have to wait for the last aircraft to take-off and all the bombers to assemble.
Edit 2: operational considerations like the desire to have more performance also might mean the need for to bomber to flight lighter than maximum weight.
Edit 3: landing ground facilities and runway length.
For a start you need to get weights.These are operational numbers:
BR.20 1795km 325kph(5000m) 1000kg bombs 1800kg fuel 150kg oil 340kg crew 54kg guns 72kg ammunition, 180kg radio, 16kg foto, 8kg others. 6693kg empty. Total 10313kg.
S.79 1845km 360kph(5000m) 1000kg bombs 1770kg fuel
Z.1007bis 1795km 368kph(5000m) 900kg bombs 2230kg fuel
Now there are other considerations, what would be the mission altitude, range backup, wind for or against?, weather, route? how much time at maximum speed/power? finally aircraft condition and crew training. And crew quantity. For example the crew for S.79 above is 4 =340kg but S.79 operated often with 5 and sometimes even 6 when with naval observer.
Another, some bombs are not really their nominal weight. The Italian 250kg bomb is 259kg and 100kg SAP bomb is 109kg, the ASW 160kg bomb is 178kg, 500kg bomb is 508kg and the 800kg bomb is 822kg
Edit: a large raid also means first aircraft have to wait for the last aircraft to take-off and all the bombers to assemble.
Edit 2: operational considerations like the desire to have more performance also might mean the need for to bomber to flight lighter than maximum weight.
Edit 3: landing ground facilities and runway length.
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Regarding Dili's "Edit 3".
I found two airfields used by Sm79's near the Libyan border. One was T5 and the other was at El Aden.
Flying from El Aden to Alexandria, armed with torpedoes (not bombs):
"The departure airport had only 1,000 m (3,280 ft) of runway for takeoff, so two of the fuel tanks were left empty to reduce weight, giving an endurance of five hours for a 4.33 hour journey."
Distance from El Aden to Alexandria: 574 km (357 mi). Round trip: 1,148 km (714 mi). The Sm.79's could do this.
I believe the next closest (and also main base) Sm.79 airfield was at Benghazi and not Derna as I gave earlier. The planes that flew from El Aden were relayed in. I would say Dili spotted the problem (runway length).
Flying from Benghazi, distance = 941 km (584 miles). Round trip: 1,882 km (1,168 m).
Maximum bombload 1,200 kg. Dili's range is 1845 km using 1,000 kg. Conclusion: To fly from Benghazi is too far with max bombload. The bombload would have to be reduced, possibly by half, to give another 30 minutes safety of flying time.
I think I have my answer. Thanks all!
I found two airfields used by Sm79's near the Libyan border. One was T5 and the other was at El Aden.
Flying from El Aden to Alexandria, armed with torpedoes (not bombs):
"The departure airport had only 1,000 m (3,280 ft) of runway for takeoff, so two of the fuel tanks were left empty to reduce weight, giving an endurance of five hours for a 4.33 hour journey."
Distance from El Aden to Alexandria: 574 km (357 mi). Round trip: 1,148 km (714 mi). The Sm.79's could do this.
I believe the next closest (and also main base) Sm.79 airfield was at Benghazi and not Derna as I gave earlier. The planes that flew from El Aden were relayed in. I would say Dili spotted the problem (runway length).
Flying from Benghazi, distance = 941 km (584 miles). Round trip: 1,882 km (1,168 m).
Maximum bombload 1,200 kg. Dili's range is 1845 km using 1,000 kg. Conclusion: To fly from Benghazi is too far with max bombload. The bombload would have to be reduced, possibly by half, to give another 30 minutes safety of flying time.
I think I have my answer. Thanks all!
Regia Aeronautica operation rules of thumb for bombardment. This is in page 177 of Nino Arena book but not all airplanes are similar so i guess this are rough rules. For the discussion the most interesting is the fuel rule.
Squadriglia: 9 aircraft, 7 operational.
Monthly war flights: 15
Max bomb weights: 1000kg - Note: i have example of missions with more than 1000kg but they are very rare.
Max fuel per airplane: 2/3 of full
Rounds per 7.7 MG per action : 500
Rounds per 12.7 MG per action : 350
Monthly actions with bombs : 15
Monthly consumption of machine guns ammunition: 4 actions
Squadriglia: 9 aircraft, 7 operational.
Monthly war flights: 15
Max bomb weights: 1000kg - Note: i have example of missions with more than 1000kg but they are very rare.
Max fuel per airplane: 2/3 of full
Rounds per 7.7 MG per action : 500
Rounds per 12.7 MG per action : 350
Monthly actions with bombs : 15
Monthly consumption of machine guns ammunition: 4 actions