Return of the Behemoths

At work.

Sorry for not being able to quote sources.

I regards to one of the lost American Zepps? The Acron I think. I am sure it was not just 'The storm.' as is oft quoted.

From memory and again I apologize for having access to sources atm BUT said machine was an 'expatrated' vehicle taken from Germany after armistice of WW 1.

Following taking delivery the American's re-worked her so as to take on specialty modified fighters. Of which I think she could carry 6 to 8.

Her engines were also mounted within her centre line, driving propellers by extension shaft. The up side being that said props could, in fact rotate to assist in maneuvering. The down side that the stern props were inljne with the forwards and hence suffered sone efficiency loss due to the formers 'Prop wash'.

Now.... in the process of her conversion/lengthening, her stern lower rudder was no longer actually attatched to her spine, or keel. Hence, during said storm, this was the point of failure and leading to her loss.

Also of note, her compliment of fighters had not alighted aboard either but with the loss of their mother ship (And the government disinclined to building a replacement. Even with the corrections of her defect) I think they sadly spent their remaing years as novelties and possible trainers.

Now, were she properly structurally refitted, then an airship loitering in the 'Atlantic gap' with a brace of recoverable and dangerous fighters would have been quite a welcome thing for those souls facing the wolf packs.

As for the max altitude of Zepps? I too did not know the max envelope characteristics and though their limit below 10k was just due to the primitive state of pressurization technology of the day.
 
At work.

Sorry for not being able to quote sources.

I regards to one of the lost American Zepps? The Acron I think. I am sure it was not just 'The storm.' as is oft quoted.

From memory and again I apologize for having access to sources atm BUT said machine was an 'expatrated' vehicle taken from Germany after armistice of WW 1.
....
Following taking delivery the American's re-worked her so as to take on specialty modified fighters. Of which I think she could carry 6 to 8.
Akron was built at the end of the twenties. You are probably thinking of USS Los Angeles, which apparently (wiki) never carried aircraft but did some hook-on/off experiments. Akron and Macon were designed with hangar space for 5 aircraft each, which is a lot less than I thought, for some reason I was also thinking 8 or so.
It also seems the aircraft were about the heft of not a Gloster Gladiator, not a Gloster Gauntlet, but a Gloster Gamecock. Fully loaded weight of all five about that of two Spitfires or lightly loaded Swordfish, or one and a half TBDs. Which suggests some radical enlargement of airships or lightening of aircraft will be required.
 

CalBear

Moderator
Donor
Monthly Donor
At work.

Sorry for not being able to quote sources.

I regards to one of the lost American Zepps? The Acron I think. I am sure it was not just 'The storm.' as is oft quoted.

From memory and again I apologize for having access to sources atm BUT said machine was an 'expatrated' vehicle taken from Germany after armistice of WW 1.

Following taking delivery the American's re-worked her so as to take on specialty modified fighters. Of which I think she could carry 6 to 8.

Her engines were also mounted within her centre line, driving propellers by extension shaft. The up side being that said props could, in fact rotate to assist in maneuvering. The down side that the stern props were inljne with the forwards and hence suffered sone efficiency loss due to the formers 'Prop wash'.

Now.... in the process of her conversion/lengthening, her stern lower rudder was no longer actually attatched to her spine, or keel. Hence, during said storm, this was the point of failure and leading to her loss.

Also of note, her compliment of fighters had not alighted aboard either but with the loss of their mother ship (And the government disinclined to building a replacement. Even with the corrections of her defect) I think they sadly spent their remaing years as novelties and possible trainers.

Now, were she properly structurally refitted, then an airship loitering in the 'Atlantic gap' with a brace of recoverable and dangerous fighters would have been quite a welcome thing for those souls facing the wolf packs.

As for the max altitude of Zepps? I too did not know the max envelope characteristics and though their limit below 10k was just due to the primitive state of pressurization technology of the day.
Both USN airships of the Akron class were U.S. designed and manufactured, with the aircraft carrying feature one of the initial design elements. The fighter carried, the F9C Sparrowhawk was a sibling of the F7C Seahawk carrier fighter.

Max carry was five aircraft, four in single place hangers and one on the "trapeze". Akron had structural members that blocked the rear two hangers (something that was corrected during construction of the Macon) limiting her to three aircraft, a refit was scheduled to correct this, but the ship was lost before it could be performed.

Airship altitude is limited by pressure differential. As altitude increase ambient air pressure decreases, this change increases the differential between the lifting bags and the outside air, at a relatively modest altitude it becomes necessary to vent lifting gas to prevent bag rupture. This same venting reduces the lift available to the airship until the available lift is less than the weight of the airship. While this can be somewhat managed at altitude by maintaining a speed great enough to get a degree of dynamic lift from the airship's hull, and by carrying supplies of high pressure lifting gas in bottles, there is a point where maintaining lift becomes effectively impossible. There are now some various methods that can counteract this effect (including the theoretical pressurizing of the entire hull to maintain lower pressure, although current aircraft pressurization methods would be exceptionally difficult to achieve in any large rigid airship design, and would make the construction cost prohibitive while adding significant weight, reducing the usable fraction of lift).

The reality is that airships were a fascinating, even elegant, stopgap measure that served a role while engine technology matured enough to allow heavier than air aircraft to achieve sufficient range and lift. There are niche roles that the type can fill to this day, but these are limited and in most cases the RoI is somewhat questionable.
 
Airship altitude is limited by pressure differential. As altitude increase ambient air pressure decreases, this change increases the differential between the lifting bags and the outside air, at a relatively modest altitude it becomes necessary to vent lifting gas to prevent bag rupture. This same venting reduces the lift available to the airship until the available lift is less than the weight of the airship. While this can be somewhat managed at altitude by maintaining a speed great enough to get a degree of dynamic lift from the airship's hull, and by carrying supplies of high pressure lifting gas in bottles, there is a point where maintaining lift becomes effectively impossible.
Ah, and I suppose the fact that weather balloons can reach 60,000+ feet without rupturing is explained by the fact that they are only partially inflated while on the ground, and reach full inflation at altitude. This would be impractical for an airship because of the weight of the structure and outer bag. I suppose one could imagine a hybrid hot-air/helium airship that used, obviously, hot air to get off the ground and up to a few thousand feet so that the ballonets could similarly be under inflated on the ground like weather balloons, but I doubt it would be practical at the time (or perhaps today).
 

CalBear

Moderator
Donor
Monthly Donor
Ah, and I suppose the fact that weather balloons can reach 60,000+ feet without rupturing is explained by the fact that they are only partially inflated while on the ground, and reach full inflation at altitude. This would be impractical for an airship because of the weight of the structure and outer bag. I suppose one could imagine a hybrid hot-air/helium airship that used, obviously, hot air to get off the ground and up to a few thousand feet so that the ballonets could similarly be under inflated on the ground like weather balloons, but I doubt it would be practical at the time (or perhaps today).
Correct. If you look at a weather balloon at sea level it sort of looks like a child's ghost costume:

104335-004-7B6F5EB5.jpg


But at altitude it looks like this:

balloon3_0.jpg
 
Can we please move away from weather balloons and back to Rigid airships carrying parasite aircraft :rolleyes:

That said if you really must look into Balloons and Blimps this is an interesting read, also some great outside the box ideas (plus they mention FAC's) ;)

Airborne aircraft carriers an idea whose time has yet to come
 
Top