109G/la-5/7 and the slats

[Angus]

Nice article. And a VERY nice webside
I see that some of my speculations booed on further up in this thread are brought in it.
Like this:
"We haven't yet seen a single reliable account about pilots wiring the Bf 109's slats shut in the western front. Only rumours and claims. In Africa this might have happened - primary reason why to do it was the dusty conditions. The sand dust made the slats jam, also early E versions were prone to slat jam. Wiring slats shut is plausible if you're operating in dusty conditions of Africa or Russian plains at summer. If other slat deployed and other was jammed, that would be most problematic. But if you had long, good runways - like you most likely would in Africa - wiring slats might not be a problem for landing."

Sand and dust, mud and ice, and a quirk with the E model.
Might explain it all

Or as Rall said:
"Q: Did you use this extra lift from the slats in combat?
A: Not at all. I mean, its also a matter of experience of the pilot, you know?  When I think of the Russian... This is another thing, of the Russian airfields. In the wintertime you had mud and fall. MUD.  And we had problems. When you takeoff, you roll and roll, you know?  You get the mud into the cooler, ja?  And we tried to overcome this by all technical gimmicks which didn't work."

[agent 009]

Mud into the oil cooler intake under wing I assume that means.

Hey Angus, how is the tree situation in Iceland? I've read a book or 2 bout Iceland. Am of Norwegian descent.

Worlds strongest man was from Iceland.

How many Brits were stationed there in 1940? How many ships?

[Angus]

Hey Agent.
The tree situation is .... low...not a lot of them.

Norwegian counts like a cousin.

World Strongest man, yes, and one after another. I think we had the title like 8 times.
To boost the ego of a micro-nation like us, we had Miss World at the same time. Untolerable, lol.

The Brits were stationed here, entering on the 10th of may 1940. Hitler went mad, he was a week late.
(Operation Ikarus I think)

Now, there is lots of warstories and warmaterial from here rather unknown to the rest of the worls. Some food for you:

- The USA took over the garrison of the island in most parts BEFORE entering WW2. That was Springtime 1941.

- One of the first Enigma machines caught by the allies was caught off the southern shore here when a U-Boot got overpowered by a well aiming single aircraft! I think that was in 1940, but can look it up

- The Garrison here was 50.000 strong in mid war. Due to the action of an Icelandic double agent, the Germans thought it to be more, - like double. This is told to have lead them to tying down more troops in Norway than necessary.

- Lots of ships stopped by in WW2. Entire convoys on the murmansk route would also regroup and refuel here. The sad PQ-17 went off from Iceland. In 1940 one of my grandfathers rode 200 km on his bicycle to see HMS Hood at anchor

- My other Grandfather was a fisherman. He turned to farming when the seas became dangerous, - German U-boats sank many a fishing boat. Ironically, my wife's grandfather, a German, was drafted into the U-boat service, being an engineer.
Thank god they never met.....

That was that. Enjoy

[agent 009]

Well, interesting stuff. especially enigma. Wondered if Brits were thin in troop stength in 1940. Most say germans did not have shipping to invade Iceland. They did have big flying boats that could land in North fiords.  Bay of Hunafloi is not too far from capital. Summer time would mean terrain not too rough for travel.

What is it, 7-800 hundred miles across from Norway?

A couple of indian kids grew up in Iceland from Newfoundland when Vikings left. They took them back to Iceland. The kids parents had died.

Be back soon.

[Angus]

Hello, double-O-nine
The Brits were definately thin in troop strenght in 1940.
Many of their AA and cannon sites in the beginning were with dud cannons only. Made of wood.
Getting to the German invasion plans, there were 2 ships being prepared, both fast ocean liners.
It was a week or two that made the difference.
Your mileage from Norway is roughly correct, however our shortest neighbour (I will have to check this out better) is actually Scotland.
I never heard this about the indian kids, but of course about everything else regarding the viking explorations.

Will be back, gotta go

[agent 009]

Well that is interesting. I had the thought that captured Norwegian ships could be used. Brits were very busy in summer of 40 with BoB.

Resupply is next issue. I've been called an idiot for mentioning air supply & U-boat supply. It's not that far fetched. Many German aircraft have enough range, even for 2 way trip. Condors, Viking flying boats etc.

Food & shelter would be solved locally. I don't think resupply is the main problem with Iceland. Hanging on to it is.

Daughter of fire is a good Iceland book. Pirates from Tunisia took 200 Icelandic souls to middle east, ( white slavery ), Long ago. only 12 or so ever made it back.

Pirates have been a problem in Icelands past. As have English, & Russian fishing boats.

Get many Narwhals in your area?

[Angus]

Hey again.
Narwhals, nope.
Submarine wrecks from WW2, yes
look to http://www.uboat.net
The editor is an icelander

There were some raids and therefor casualties. Condors and He-111 from Norway. They would sometimes sink some shipping, and take potshots at various things. My hometown got strafed in 1940 or so.
The supply of food wasn't all that bad, we have quite some agriculture, and the fishing grounds are good. There was a lot of export to the British during the war, which probably lead to the Germans strafing the boats.

Then to the pirates. It was quite a story, - they came all the way from Algiers.
Although the nation was short of weapons, they got beaten off on some locations, and even suffered some casualties. But they took slaves, yes, and some were later bought back by the Danish king.

Now, the fishing boats of the Brits were a nuisance, and we had "wars" with them some 4 times about the fish.
Cannons were actually used on the Brits, last time in 1976!!!
In Cod war II (out of 4) the RN had 38 military vessels around the country!!!!
Anyway, we won them all

[agent 009]

Cannons wow! Iceland beats England. Don't see that in history books much then do we?

Yes I think a german garrison  would not have trouble eating or being resupplied from the air. Whether they could have pulled off an invasion is still an open question. British navy would have sunk resupply ships.

If not in 40, then for sure by 41 I think an allied landing to take it back would have taken place. But that would have given Germans better part of a year use of island.

[Angus]

As a strategic point in the Atlantic campaign, Iceland was a must.
For shelter, refuelling, air ops etc. You can see on the Uboat.net that there are many sub wrecks around our island.
BTW, the British also occupied the Faroe Islands, - same purpose.
They were here on the morning of may 10th in 1940, - same date as the Germans rolled into the Netherlands.
We were really lucky that the Germans didn't beat them to it, - firstly the abovementioned resupply problem, secondly they had a reputation for being bad masters, and thirdly, - probably, - there would have been some fighting perhaps.
The Brits were rather welcomed, they didn't mess with internal affairs, and they payed for what they got, products, workforce etc.
It turned all out to be an economical BOOM, so the WW2 was actually mostly a very prosperous time.
The dark side was the sinking of fishing boats and merchant vessels under Icelandic flag, - even in 1945 the biggest passanger liner was torpedoed.  German aircraft also occasionally appeared, bombed and strafed. Some crashed here or were shot down.
Then there was espionage, and double agents were also active!

Then to the cod wars. The moving of our fishing border was as follows, - 2-4 miles, 4 to 12, 12 to 50 ,and 50 to 200.
Every time we had to jostle with the English, quite a funny affair.
in 1973 it was 50 miles, and 1975-76 the 200 miles, - those were the toughest ones. The Brits sent frigates and tugboats, and there was a lot of bumbing into each others. The Icelanders had 6 patrol ships, like 1000 tons max, doing only 20 kts max.
The Brits sent frigates 3 times the size, with 36 kts, but less nimble, and very much more lightly built, - our patrol ships are built for sailing in driftice, so thick skinned.
The Icelandic tactic employed a secret weapon, hehe, a towed cutter unit used to snap the trawler's pulling wires, sending their entire expensive fishing gear to the bottom of the ocean.
So, there were dogfights when the British frigates and tugboats tried to block, and ships would on frequent occasions smash into each other.
There was one attempt for sinking, - a British frigate caught an Icelander by some 90 deg angle, and he tumbled to 70 deg listing. But he tumbled out of the attack and in his new position managed to cut a trawler net within a minute.
The same Icelandic captain used cannon, that was in 1976. He had ordered a British trawler to stop, but he steamed ahead. There was a warning shot, then he ordered the Brit to evacuate crew from the front quarters, which he promptly did. Then cannon shells were pumped into the front of the Trawler. there was ceize-fire so the Brit could explore the damage, then repeated a few times. The Brit never yealded, but had to return to docks instead.
Quite amazing stuff, I´ll see if I can find any links.
At that moment actually, political connection between the UK and Iceland was cut, and ambassadors called home!
Anyway, they gave up, and now everybody has their 200 miles, including the UK.

[agent 009]

Germans did not have a good naval plan. The Z plan was a compromise, so that germany was weak in all categories. Should have made mini carriers, more disguised raiders ready in 39.,(1st raider wasn't ready til 40! ),good armed transport craft, & of course loads of U-boats. hindsight is 20/20. & the age of the big battleship had not passed yet. More pocket battleships would have better use of steel.

Yes I did read about 50, then 200 mile limit. The book also mentioned Russian & Japanese ships.

In the book German raider Atlantis, it mentions the British would use the north fiords of Iceland for shelter when sea was rough. This was one reason Atlantis made it into Atlantic as she braved the storms while Brit ships were in the fiords.

Back to trees. many types of trees were attempted in Iceland. Some worked, some not. An apple tree was planted in Reykyavic & it only produced apples once, something like that. This was in 1840? Have to read it again. Some tees have been imported from Colorado, & some from Russia.

[Mace2004]

Cool thread...lots of speculation.  Although I can't vouch for what the German's actually did or did not do regarding slats I do have some experience actually flying with aerodynamic slats that might be relevant.  I also agree with the comments as relayed by Grits.  The Douglas A-4 had aerodynamic slats that appear to be almost identical to the German design...at least as well as I can recall from the last time I saw a WWII German design.  This design is also the same as the North American F-86 and T-39 which share the same wing/slat.

Do slats stick?  Yes.  Even though they're relatively simple devices they still have to be cleaned, lubed and adjusted.  Some of the individual planes I flew had a reputation for a sticking slat that the maintenance crew just couldn't get right.  Maybe the wing was tweaked, maybe the tracks were worn, maybe someone ran into it at some time with a truck but the more flight time an airplane had the harder it was to keep them working right.  The slightest bit of stickiness during preflight usually meant you'd see problems in the air.  If we had maintence issues in Pensacola you can bet they were ten times worse in 1944 Germany.

Do they "pop" or "clunk" when going up or down?  Absolutely.  They're either in or out and the change is quick and noticable.

When one sticks can it cause the airplane to depart from controlled flight?  Yes, especially if it sticks in the fully up position and you snatch on a buttload of aft stick.  At low speed the airplane simply rolls off a bit on the stuck slat side; however, at high speed and if you're unlucky you can get a violent departure. To give you an idea of how critical the wing leading edge can be, some F-14 departures were tracked down to differences in the paint thickness and texture on the wing leading edge (which is a powered slat on the F-14).  We ended up stripping the slats down and leaving them in bare metal.

When one sticks or if they deploy at different times does it affect your ability to do guns tracking? Yes, alot; however, if you're trying to do an evasive maneuver asymetrical deployment sometimes helps.  Let's say you're doing a guns defense with a barrel role and you snatch and roll at the same time.  The upgoing wing has higher AOA and its slat pops out before the other side...you'll get better initial roll so it can help.

Are there work arounds? Yes.  As you approach slat deployment you can "pop" the nose up and force the slats out then keep the AOA you have.  Aerodynamic slats typically deploy at one AOA and retract at a bit lower AOA so if you get them out they'll typically stay out unless you significantly lower AOA.  Once you have them out it's more stable then with them in and you definently don't want to try to track right at critical AOA and have them popping in and out.  This makes true guns tracking impossible.

Do slats affect lift?  Yes.  They shift the lift curve to the left.  In most designs I've seen slats not only provide some boundary layer control but, since they slide forward and down they increase both the camber and area of the wing.  Complex flaps can the same thing, sliding aft and down and when they're sloted they also assist boundary control on the trailing edge.  Combining slats and flaps moves the lift curve left and up.

Do slats increase drag?  Depends on how you look at it.  At the point the slats are coming out induced drag is predominate and the higher the AOA, the greater the lift, the greater the drag.  Since the slats permit a higher AOA you'll get more drag due to lift; however, by delaying the stall you reduce the drag that would be caused by boundary layer separation so it's a tradeoff.  In reality you're flying where you can't go without the slats so drag isn't really the point, critical AOA and power are.

Is it reasonable to assume someone might want to fix the slats in the up position?  Yes.  As Grits mentioned the Blue Angels did exactly this (they also chromed them which was pretty sharp).  Of course there is a trade off in that you lower your critical AOA and, at least in the A-4, the airplane is less stable in tracking as you approach stall.  Although the Blues did this for formation flight, some of the Germans MAY very well have done the same thing for fighting especially given the conditions they operated and IF the slats were actually sticking in one position but I have no idea if they actually did or not...it's just a reasonable assumption.  Personally, I'd think a smart pilot would just take slat operation into account and use them even if they were sticky but not stuck(ya otta use all the tools in your toolbox).

Why don't small civilian airplanes (puddlejumpers like the C-182) have aerodynamic slats?  They add expense, complexity and maintenance issues for minimal payoff (just like simple vs fowler flaps).  As others have mentioned, civilian STOL aircraft typically have fixed slats (which are really just leading edge slots for boundary layer control) and have a justification for other, more extensive high lift devices like fowler flaps, vortex generators and fancy wingtips but for typical general aviation it just isn't worth it.  All modern fighters either have slats or leading edge flaps for both landing and maneuvering although these are now all powered and controlled by the Flight Control System.

Is AH accurate?  Yeah, I'd say so.  Like Grit's Dad I was amazed they modeled the slats and they sure seem pretty realistic to me, just glad they don't model maintenance issues.

Thought you all might find this informative.

Mace,
CDR USN (Ret)

[Charge]

TY Mace, it was informative and nice to read first hand experiences of slats.

However, I'm not so sure if AH models slats accurately. This is why: The wing profile, say NACA 2412 has certain max AoA limit at certain R number, this limit for NACA2408 is lower (it's thinner). So we can see that the profile affects the max AoA. If the max AoA for 2412 is 15 deg for a certain R number the slat can extend the max AoA much furter for a cost of more drag, of course. So you should be able to pull more AoA that another a/c with NACA 2408 even without the aid of slats.

Flying a 109 in AH, you do not get the impression that the slat "extends" your max AoA, but only lets you pull as much AoA as a/c with larger wings without slats, as in fact it should allow you to pull quite a bit more than those. Combined with enough power the slats should be a good thing if turning is considered. Now they merely warn you of the incoming death in form of slow speed. It would be nice to have a AoA and G counter in E6B so I could prove myself wrong in this case...



-C+

[Tilt]

Originally posted by Mace2004


Thought you all might find this informative.

I did thanks..............

[Mace2004]

Originally posted by Charge
Flying a 109 in AH, you do not get the impression that the slat "extends" your max AoA, but only lets you pull as much AoA as a/c with larger wings without slats, as in fact it should allow you to pull quite a bit more than those.  

--Not necessarily if the basic wing (i.e.., without slats) has a low tolerance for high AOA or if the aircraft has a high wing loading in which case the slats may only help it be competitive with other wings.  I have none of the charts that many in this game have in order to do a reasonable comparison but, just from my observation, the 109 series appears to have relatively small wings and probably higher wing loading.  

Assume you have two identical aircraft with the same profile wing but one wing is smaller giving a higher wing loading.  The smaller wing aircraft would have to pull higher AOA for the same turn radius and it will reach critical AOA first.  Give the small wing slats and performance will improve but there's no way to know if it'll still be less than, equal to, or better than the larger wing without empirical data.  Any of these results are possible depending on the abilities of the basic wing.  

Personally, I wish HT would publish VN diagrams for all of the aircraft in the game which would give much more useful information than the speed profiles that are available.  Obviously, one of the first questions people ask is "how fast is it?"  I'd rather know how well it turns and at what speeds in comparison to other aircraft... corner velocity, max sustained turn, max instantaneous turn, etc.  VNs are the charts we pulled out to determine how we would fight another, dissimilar aircraft.  

Back to AH, regardless of slats or wing loading, the only thing we can really see is ability to turn in relation to others and there are of course many variables.  I'd have to assume that HT modeled it correctly but who knows?

Mace

[HoHun]

Hi Mace,

>Personally, I wish HT would publish VN diagrams

Sounds interesting! How are VN diagrams organized?

(We had a discussion here on the most useful form of organizing data on aircraft manoeuvrability a while back, and we weren't happy with what we had back then.)

Regards,

Henning (HoHun)