Friedrichshafen Bombers

[alan peacock]

Anyone tell me why the Friedrichshafen G bombers
were not used during the air raids on Britain. I believe
they were used on bombing missions on the Western Front
including raids on Paris. I know Gothas, Giants and Zeppelins
raided Britain but I find no reference to Friedrichshafen bombers.
Also has anyone any info. on Allied pilots who brought down
any of these types of aircraft.

[Romani]

Alan, I wondered the same thing, wondered why the Germans had so many types of bombers. The Windsock Datafile on the Friedrich will answer your questions, but the answer is: range.

The Friedrich had an endurance of 5 hours and could carry a 1,000 kilo bomb load, the Gotha GV had a payload of only 600 kilos but a range of 840 km (don't know if that's how far can it travel in a straight line with full fuel, or round trip)
The Zeppelin Staaken RVI had an endurance of 7-10 hours with a 2,000 kilo bomb load maximum, but of course it was a "Giant" much larger than the Gothas.

[Ransom E. Olds]

I think maybe the ceiling of the Gotha was an consideraton too; even if the Friedrichshafen's bombload was traded for fuel capacity it still didn't have the climbing ability of the Gotha. This wouldn't have been so much at issue in night operations, but in the early daylight raids it would have been a significant consideration. Ransom

[Romani]

I finally got around to look and compare the performance figures, so I can give you a more detailed answer

Freely quoting from Munson's Bombers 194-19

The first of the German bombers were the AEG G types, tractor airplanes unlike the others that were pushers, the most widely built was the GIV entering service in late 1916, the bomb load was 350 kg, service ceiling 4,000 meters

Lacking both the range and the lifting power of the Friedrichschafen and Gotha G types, the A.E.Gs. where flown mainly as day and night tactical bombers over comparatively short ranges up to about 700 km (435 miles)

Now, about ranges. Coming from WWII aviation, I was always mystified by the measuring of endurance in hours in Great War planes. It makes actually a lot more sense, whereas in WWII range is measured as going from airfield A to bomb target B (like London, Berlin, Schweinfurt or Ploesti) carrying X bombs for Z kilometers, or for fighters how far they can accompany said bombers, distance Y, in their route to target B , in WWI what really matters is how many hours can a 2 seater stay loitering over the trenches taking photos, or spotting for artillery, or for a fighter how much time can be airborne sweeping for those enemy 2-seaters.

So measuring endurance in hours is a more appropiate unit for most WWI airplanes, but when it comes to bombers, is more useful to know how far they can reach.

Back to the AEG, given that maximum speed was 145 km/h and endurance is listed as 4 1/2 hours, then we can estimate that the range figure is total distance it can cover with a full fuel load in a straight line, so the operational range (round trip) would be about 300 km, assuming a lower cruising speed with optimal fuel consumption and cancelling fuel spent climbing with the bomb load to the lower fuel consumption on the return trip once the airplane has dropped its bombs and fuel tanks are half emptied.

Applying the same reasoning to the Gotha mentioned early, this would give it a range of 400 km.

The Friedrichschafen GIII appeared early in 1917 and was an improvement over the AEG GIV being larger, carrying a heavier bomb load, longer range, and a higher ceiling (4,500 m)

What is surprising is that there's very little difference between the Friedrichschafen GIII and the Gotha GV, Munson says the Friedrich is a bit smaller, but I compared the dimensions, and they are virtually the same in span and in length the Friedrich is actually bigger by half a meter!

However the Gotha is taller having a larger space between wings. The Gotha is 4.30 m tall and the Friedrich 3.66m

Wing area is 89.5 sq meters for the Gotha and 86.00 for the Friedrich

Take off weight 3,975 kilos Gotha and 3,940 the Friedrich

So far the aircraft are so similar that nothing explains why the Gotha has a ceiling of 6,500 meters, 2,000 more than the Friedrich

Before starting to wonder about airfoil efficiency (wild speculation) or thinking that the wider gap between wings in the Gotha causes less interference and results in higher lift (likely) let's look if there's a simpler explanation.

The Friedrichschafen did indeed accompany the Gothas in some attacks on Britain, according to Munson.

Let's look at the bomb load, a data this is misleading because typically reference books quote the maximum payload without accounting for reductions on longer range missions.

The Friedrichschafen max bomb load was a whopping 1,000 kilos, but that was for short range missions. Munson again:

Bomb load of the GIII for normal ranges was 500 kilos, of wich 100 kilos was carried internally and the remainder on racks under the fuselage

It's worth pointing out that external bomb loads would cause drag, probably not very much, but every drop of gasoline counts.

Looking at the Gotha, top load , 600 kilos. Munson

Their typical bomb load on cross-Channel raids was six 50 kilo bombs, about half their maximum load

So far we see that the Gotha is so similar to the Friedrich than the only explanation for it's increased range was simply trading bombs for fuel.

I don't know if the 6 bombs could be carried internally, but even if they could, a quick perusal of the Windsock Gotha Datafile shows that the bombs had to be carried externally due to balance considerations (the Gotha was tail heavy) so that nullifies the advantage the Gotha might have for less drag. Again, it's an even match between the types.

So in conclusion, they are very similar planes in design and performance, but each had a different mission: the Friedrich was optimized for continental raids with shorter range and heavier bomb loads, and the Gotha was optimized for long range bombing. It might have been unfeasible to convert the Friedrich to long range missions, I am not an airplane designer, but is pretty obvious that shifting weights in an airplane is very tricky and it could have rendered the Friedrich unflyable.

What about Ransom said about ceiling? The Gotha higher ceiling might have simply been due to carrying fewer bombs. Even if take off weight is the same, as fuel is consumed the Gotha simply can climb higher.

Also, Munson quotes for the Gotha an stratospheric (for WWI) ceiling of 6,500 meters! and this is repeated uncritically in other sources.

But when the Datafile is checked, for a host of reasons it turns out that, first, for England raids the Gotha was overloaded and the first daylight raids were flown at 5,000 meters, and second, performance degraded, and later raids were flown at 4,000 meters. So much for the supposed ceiling advantage of the Gotha over the Friedrich.

And later on, night raids were flown at much lower altitudes, starting at 2,500 meters and progressively lower to 1,700 m.

Very interesting subject, thanks Alan for the question, I always wondered but was too lazy to search for the answer.

[Dan_San_Abbott]

Alan Peacock:
The Friedrichshafen Bomber series lacked the range to bomb England and return. The Fdh.G.III had a range of 600 km and a bomb capacity of 800 kg
(1760 lbs.) Commencing with the Fdh.IIIa the empty weight was increased from 2695kg to 2880kg. there were changes in the wings and a compound biplane tail. The disposable load of the G.III was 1255 kg of which 800kg was the bomb load. With the G.IIIa disposable load was 2100 kg. this is an increase of 2100 - 1255 = 845kg. The bomb load was increased to 1080kg, an increase of 280kg. That means 565kg of weight was added in fuel and oil capacity. This means the range was increased. I don't have the data on the range.
The wing spans were increased from the G.III with 23774mm to 24000m on the G.IIIa, to 24720mm on the G.IIIb, to the G.IV and G.IVb with 27600mm.
and G.IVb 24720mm. The G.III and G.IV had conventional tail surfaces. The G.IIIa, G.IIIb, G.IVa and G.IVb had compound tail surfaces.
the Friedrichshafen bombers were superior to the Gotha bombers in every respect except range. In 1918, Idflieg gave Gotha an order for 50 Fdh.G.IVa(Go.) to manufacture.
Blue skies
Dan-San

[alan peacock]

Romani,
Many thanks for your and detailed reply.
All info. is most welcome and appreciated.
Your comments are very interesting and
I thank you for your efforts.

Cheers.
Alan.

[alan peacock]

Dan San,
Many thanks for your reply and detailed info.
As always it is most appreciated.

Cheers,
Alan.

[alan peacock]

Ransom,
Thankyou for your reply, the info. I have received
has been excellant and answered my query perfectly.

Cheers,
Alan.