Heavy Bomber. Yet Again

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Dunash
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Re: Heavy Bomber. Yet Again

#61

Post by Dunash » 04 Jan 2014, 11:14

stg 44 wrote:When it entered production the He177 had dropped the dive requirement and much of the engineering that went with it. It still lacked structural stability though thanks to the tail assembly among other things. As it was the He177B required more materials and extra assembly thanks to having larger wings as well as extra two propellors and engine nacelles, plus a much larger tail structure that required more work, but improved the stability issues. Also the He177B was longer IIRC.
But surely the need for larger wings and extra propellers/engine nacelles would have been a worthwhile trade off to eliminate the gearboxes required by the DB606. In any case the gearbox itself was the source of some of the DB606's problems.

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stg 44
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Re: Heavy Bomber. Yet Again

#62

Post by stg 44 » 04 Jan 2014, 17:27

Dunash wrote:
stg 44 wrote:When it entered production the He177 had dropped the dive requirement and much of the engineering that went with it. It still lacked structural stability though thanks to the tail assembly among other things. As it was the He177B required more materials and extra assembly thanks to having larger wings as well as extra two propellors and engine nacelles, plus a much larger tail structure that required more work, but improved the stability issues. Also the He177B was longer IIRC.
But surely the need for larger wings and extra propellers/engine nacelles would have been a worthwhile trade off to eliminate the gearboxes required by the DB606. In any case the gearbox itself was the source of some of the DB606's problems.
IMHO yes, but it would be more costly in terms of materials.


Carl Schwamberger
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Re: Heavy Bomber. Yet Again

#63

Post by Carl Schwamberger » 04 Jan 2014, 22:33

Cheaper in materials than all the aircraft lost to engine fires?

Dunash
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Re: Heavy Bomber. Yet Again

#64

Post by Dunash » 05 Jan 2014, 11:35

So you have a revised wing structure, two extra engine nacelles and propellers, basic aeronautical engineering which would consume some extra aluminium and steel. This would eliminate two gearboxes requiring casings, gears and bearings, the latter two requiring good quality steel. It would also simplify the wing structure.

But there are other benefits to consider. engine changes/maintenance would be simpler due to improved accessibility, no gearboxes to maintain and the possibility to use a propeller already in use on other aircraft.

And lets not forget that Avro did this with the Manchester producing the excellent Lancaster in the process.

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phylo_roadking
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Re: Heavy Bomber. Yet Again

#65

Post by phylo_roadking » 05 Jan 2014, 15:15

So you have a revised wing structure, two extra engine nacelles and propellers, basic aeronautical engineering which would consume some extra aluminium and steel. This would eliminate two gearboxes requiring casings, gears and bearings, the latter two requiring good quality steel. It would also simplify the wing structure.


Actually - it's going to hugely complicate the revised wing structure because of the radically different stress factors of two extra outer nacelles and engines 8O The wing beyond the now "inner" nacelles would have to be greatly strengthened....which means the main wing spar itself would have to be.
And lets not forget that Avro did this with the Manchester producing the excellent Lancaster in the process.
Unfortunately it wasn't that easy ;) It was the extended wing and extra nacelles that created MAJOR issues during prototype testing - extra flex, the outer wings de-skinning, nacelle skinning and engine covers shedding repeatedly etc...
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Carl Schwamberger
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Re: Heavy Bomber. Yet Again

#66

Post by Carl Schwamberger » 05 Jan 2014, 18:44

One of the reasons Boeing & the other US makers prefered new wing designs for their four engined aircraft.

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Re: Heavy Bomber. Yet Again

#67

Post by thaddeus_c » 31 Mar 2014, 12:37

posted this question under LW section but will try here.

would a push-pull design on the DO-317B variant of DO-217 using the DB-610 "power system" even be feasible?

Dornier was smitten with that layout, always viewed the DO-335 as not really having a role though?

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JAG13
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Re: Heavy Bomber. Yet Again

#68

Post by JAG13 » 16 Apr 2014, 17:12

phylo_roadking wrote:
So you have a revised wing structure, two extra engine nacelles and propellers, basic aeronautical engineering which would consume some extra aluminium and steel. This would eliminate two gearboxes requiring casings, gears and bearings, the latter two requiring good quality steel. It would also simplify the wing structure.


Actually - it's going to hugely complicate the revised wing structure because of the radically different stress factors of two extra outer nacelles and engines 8O The wing beyond the now "inner" nacelles would have to be greatly strengthened....which means the main wing spar itself would have to be.
It would be far simpler than stressing a huge wing for DB, in the end it would even save weight.
And lets not forget that Avro did this with the Manchester producing the excellent Lancaster in the process.
Unfortunately it wasn't that easy ;) It was the extended wing and extra nacelles that created MAJOR issues during prototype testing - extra flex, the outer wings de-skinning, nacelle skinning and engine covers shedding repeatedly etc...
The He-177B-5 prototypes didnt have as much trouble with the change, but it did require a new twin tail to improve stability.

Had the aircraft been so modified in 1938 then late 1940 production with DB601 or Jumo 211 should be atainable.

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