Leaving aside the political factors for the moment,
would it have been technically
feasible to use airships for anti submarine
warfare during world war II?
On a similar note, was there an aircraft detection
set small and durable enough for airships
to be used in to detect incoming aircraft.
Yes, it is feasible. We did use blimps to hunt subs, and more would have been useful. You can also take a Macon like ship with airplanes and use to hunt subs. You basically get the equivalent of a 6-12 plane anti-sub carrier that can rapidly get to a needed area much faster than a light carrier (CVE). You are looking at maybe a 200 knot speed to arrive for the carrier not low 30's for a theoritical light carrier built on cruiser hull.
By the end of WW1, you have Zeppelins with lift capacity of over 80,000 pounds, so yes you can put in the radar. It just requires funding to develop. The advantage is the range to the horizon, the same basic reason we use AWACs today. Someone just has to dream up the concept soon enough and win funding. Now it can't defend itself versus fighter aircraft, but neither can an AWAC. So near land, say used in England, it will have to have dedicated fighters to protect. Over the ocean, it will be above the operational ceiling of carrier based aviation. BTW, you probably will need pressure suits too. It can also carry weapons, so it does not have to be helpless. Again, a lot depends on development budgets. Do you stick a few 50 caliber on it, or is it like the late 1940's radar controlled guns? Or just leave it unarmed? Also, Helium blimps don't go boom, the slowly deflate as hit by bullets.
Now assuming you don't change WW1 outcome and you take out the fun German scenario, where would you use it. A place like Pearl Habor (or any major naval base like Singapore). You build a small fleet of them (3-5) and have them patrol outside of the base over the ocean. It makes the enemy's job much harder since they have to deal with the likelihood of being caught up to 700 miles from Pearl. All for the cost of about a destroyer each at these levels. It makes a good TL.
So does one where the USA keeps them in service, and then lends lease these blimps to the UK for anti-submarine work. Zeppelins are a niche item. They can be useful. So much like spending on Navy Seals or subs to tap cables or SR-71, they can be a high cost per unit, low total cost item with big benefits. Or you can fight a war without them and do ok.
