"How far could airplanes/airships see?" Topic

I am planning a short "one-day" operation level naval campaign based on Dystopian Wars and have a few questions that I hope TMPers can help with.

Now the technology of the game world approximates that of WW1, so I am using WW1 for reference.

The question is: how far could a recon airplane/airship see?

I know the answer is "it depends", but "in general", how high would an aircraft searching for a surface fleet be flying and how far away can it see an enemy fleet?

Thanks in advance.

In his autobiography 'Sagittarius Rising', Cecil Lewis claimed that, flying over the British Sector of the Western Front on a clear day, he could see across The Channel to London and the Home Counties. I don't know at what altitude, but I think he was piloting an SE 5.

I believe the visible horizon at ground level is about 17 miles, so it would be a bit more from altitude.

I am using Grand Fleets 2 as my basic rules, and it does give a figure in that region (up to 20 nautical miles for very large ships).

I've also found some sites that give formulae for calculating distance to horizon depending on the observer's height, and at 1 nautical mile height the distance is about 80+ nm.

However, I have no idea what the usual cruising height for search planes and airship were, and whether it was easy for them to spot ships at that distance.

I remember flying over the town of Caledon (a small town about 45min drive NW of Toronto) on a clear summer day, in a Cessna 172 about 2000' AGL, and were just able to see CN Tower. I measured the distance on Google map which is about 35 statue miles (30 nm) away.

Actually there is a pretty simple formula at Wikipedia (I know, I know):
en.wikipedia.org/wiki/Horizon

So, if your recon plane is 1,000 off the ground, his horizon is 38.5 miles. A 6 foot tall man at sea level has a horizon of about 3 miles. To get Major Bumsore's 17 miles, you would have to be about 200 feet above sea level.
BWW

EDIT: An old set of Age of Sail campaign rules I have gives a sighting distance between ships of 30 kilometers, or 18.5 miles. That would give you an observer height of about 225 feet. Of course, that is just to sight them, not to make out any details.

Visibility distance is NOT seeing. I fly my piper cub all the time – My "visibility" is measured in miles based on my altitude. But I cannot see another airplane remotely that far away. I can see, with the naked eye, a plane about 3 miles or so away IF I really concentrate. With binoculars, I can see it maybe – maybe- five miles away.

I can see a city tower, maybe 20 miles away or so. I can see a blimp 10+ miles away without clouds. I can see – and have – a navy carrier 15+ miles away and the task force 20 miles away.

So … "seeing" is very relative to how big and distinctive the object one is looking for is …

Mark

Thanks for all the replies so far.

I guess the "consensus" so far is that ships could spot each other from the range of about 16 to 20 nm, presumably from a crow's nest.

We can assume that that is a function of both the horizon and the size of the ships in question. However, aircrafts must have been better at spotting, or they would not have been employed at all (especially airplanes, which have limited endurance).

You will be able to see large objects or structures at greater distance. Battle fleets will show up before a destroyer and another aircraft will be much shorter range

So … "seeing" is very relative to how big and distinctive the object one is looking for is …

And in the distinctive part lies the wonder of camouflage. Slap some dazzle paint on your battle cruiser, and even if the enemy can see it from a recon aircraft flying at 10000' from X miles away, they will likely not know that they saw anything at all. This is yet another reason to put dazzle paint, which is just really cool looking, on pretty much everything.

Doug

visible distance depends on height above ground level, intervening obstacles, atmospherics and other factors. If all you're worried about is height above ground level, you can use simple trigonometry to figure it out.

EDIT: As Brian W. pointed out, sighting another object is a different matter, and will actually give you a longer sighting range – you not only have your height to the horizon, but because the other object has height, you will be able to see it beyond the horizon, so you then have to calculate the distance from the horizon to the tops of the other ship, etc., to get the total distance at which the object is viewable.

Have you read any of the books about the use of airships for this very purpose? That was the proposed function of the US Navy zeppelins, so there's bound to be discussion about real-world sighting range and the practical aspects of searching with airships and aircraft. I do remember they used a scouting line of aircraft anchored by the zeppelin to extend the search swath, but not specific ranges.

I read this stuff years ago after playing ZRCV, which let you do USN zeppelins searching for Japanese fleets and airbases, but don't have any of the references any more.

Please recall that naval spotting binocs are just a bit more powerful than your average bird watchers… I'd say 20 miles would be a pretty close approximation.

Pedrobear, the real advantage in using an aircraft spotter is its speed, not the different visual range. Need to see what is 100 miles north of you? Would you rather send a destroyer that will take several hours to make the trip in each direction or a plane that can do the round trip in under an hour?

That would be a call about the weather. when they say unlimited visibly they mean it. If you have the eyes or the scopes and skill you can see all the way to the end of a straight line. If they say visibly is 2 miles then no matter how good your eyes or scopes are you can only see 2 miles. Also size and color the the thing your trying to find has a lot to do with it..

Plus, as Zyphyr pointed out, they can be remote. Station the airship twenty miles north of your task force and now you have an additional 20 miles of spotting range. This assumes you have a radio or something that can relay that information back over a distance, of course.

And don't overlook the visibility of wakes. I remember flying commercial over Lake Erie and spotting a sizable wake. It took us several minutes to catch up to the freighter that was making it. It must have been visible for at least five or ten miles behind the ship.

"Pedrobear, the real advantage in using an aircraft spotter is its speed, not the different visual range."

Ah. Eureka moment there for me.

Thanks to all for the replies.

As far as spotting another aircraft, in 'The Most Dangerous Enemy' (great book), Stephen Bungay argues that on a clear day a pilot could spot another aircraft at about two miles, or a formation of aircraft at four miles.

Mike

I think Bungay's talking about your average pilot. When your air force gets big enough, you start to accumulate genetic freaks who can see significantly farther. Supposedly, Bud Anderson and Chuck Yeager were both such freaks.

Depending on the level of detail you're looking for in your rules, you may want to single out those folks.

I saw the link to the wiki, but here's a bookmarked page I keep for handy stuff

Distance to Horizon calculator: link

20,000 feet altitude (service ceiling of a spad) puts the horizon well over a hundred and seventy miles off. You cannot see further than the horizon. How far an observer could pick out details depended on the observer

Furthermore the angle of observation becomes exponentially more shallow as you approach the horizon, meaning you are observing against more of a "background clutter" rather than from above the further out you are looking. This background clutter combined with the moving platform you are observing from, makes distance observation harder. This is why most radar observation aircraft record their data and feed it through a computer to eliminate "background clutter"

My dad flew on an AWACS in the 70's, spent a lot of time taking about the limits of the system to me after the movie topgun came out.

For the WW1 era, maximum flight altitude war only 10,000-12,000 ft. Regardless of an aircraft's theoretical ceiling, pilots could not breathe above this height. There were no oxygen regulators or supply systems in regular service. This holds true for airships as well as heavier-than-air. In WW2, when oxygen systems were generally available, they were required above 10,000 ft.

Another limitation was the resolving power of the Mark I Eyeball. Between the wars US Navy scouting planes never exceeded 1,000 ft because climbing higher only used more fuel which shortened the flying time. The 1944 US Navy Scouting Doctrine set the altitude limit for search aircraft at only 500 ft.

Weather is another factor. Are you operating in the stormy North sea with it's cloudy and foggy climate, or the sunnier climes of the Mediterranean and Pacific? Scouting aircraft needed to operate below the cloud base. Only modern radar can make searching at higher altitude practical.

" For the WW1 era … There were no oxygen regulators or supply systems in regular service. "

WW1 aircraft oxygen system. Simple, but they DID exist:
link

Thanks for the cool link!

However, such oxygen systems were not standard equipment in regular service use. And they lacked adequate regulators. The pilot held the pipe-stem end of the oxygen line clamped between his teeth and regulated the flow of oxygen manually. It was only used for special ops and was not generally available for aircrew and, as importantly, not available for the aero engines of the day which needed oxygen for efficient combustion. The lack of power at high altitude severely reduced the handling characteristics of the aircraft. The multi-stage superchargers/turbochargers used by some WW2 aircraft were yet to be perfected. Air ops routinely took place in the breathable atmosphere below 12,00 ft.

Since the original request was for a Dystopsian War, I should add that when airships climbed too high (such as climbing over mountains) they had to valve/vent hydrogen to prevent the gas cellss from rupturing due to the pressure differences. The hydrogen was not replaceable in flight and when the airship returned to normal operating altitude it lacked its original buoyancy and handled "heavy" until replenished at base.

I'll need to double check, but I remember reading about Austro-Hungarian pilots complaining that their Hansa-Brandenburg D.I's couldn't reach the Italian Nieuports which regularly flew at 4,000 – 5,000 meters.

Perhaps with the Alps to deal with they regularly operated at higher altitudes on that front.

The highest battle of WW1 was the Battle of San Matteo, fought at 12,000 feet, so I suspect that they regularly flew higher on that front.