Why did Germany use inverted engines?

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bf109 emil
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Re: Why did Germany use inverted engines?

Post by bf109 emil » 17 Apr 2009 08:47

Juha Tompuri wrote:
phylo_roadking wrote:...except this wasn't as much of a problem on the Spitfire and Hurricane with their sliding-backwards-to-open canopies
...and with inverted engines would have been even less problematic.

Regards, Juha
not really as the room made by the narrower engine block was taken up with Machine guns mounted on the cowling and thus no benefit of a narrower engine cowling was retained by inverting the engine...at best it allowed a suitable gun platform as opposed to making the smaller wings having to take both cannons and machine guns and producing higher wing loads on an already taxed wing frame/root

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Re: Why did Germany use inverted engines?

Post by Ome_Joop » 17 Apr 2009 11:11

Maybe when comparing aircraft profiles the differences between the 2 types of engines make it more clear?
The 109G-6 engine deck (even with bulges) is much more rounded vs spitfire (engine deck seems to be much larger and more streight).
Also the cockpit of the 109 seems to be more over the wing compared to the spitfire (giving the 109 better visibility over the wing but the spitfire more visibility behind the wing!).
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Re: Why did Germany use inverted engines?

Post by Ome_Joop » 17 Apr 2009 11:31

producing higher wing loads on an already taxed wing frame/root
Would the spitfire with it's landing gear mechanism in the wings (and the spits heavier weight) have the same or even worse problem?

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Bf-109 had the landing gear attached to the airframe and not to the wwing so that should make a difference.

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Re: Why did Germany use inverted engines?

Post by bf109 emil » 17 Apr 2009 22:45

Ome_Joop wrote:
producing higher wing loads on an already taxed wing frame/root
Would the spitfire with it's landing gear mechanism in the wings (and the spits heavier weight) have the same or even worse problem?

Image

Bf-109 had the landing gear attached to the airframe and not to the wing so that should make a difference.
the anchor point on the spits landing gear although wider and at the wing roots was supported by the airframe as well as the wing root, being an integral part of the airframe was extremely strong...just the wing on the bf109 was small and quite thin which gave it excellent speed, but as guns etc where placed upon it stressed the wing root

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Re: Why did Germany use inverted engines?

Post by Ome_Joop » 18 Apr 2009 08:35

bf109 was small and quite thin which gave it excellent speed, but as guns etc where placed upon it stressed the wing root
Quite thin but not as thin as the wing of a Spitfire!

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Re: Why did Germany use inverted engines?

Post by bf109 emil » 22 Apr 2009 18:21

Ome_Joop wrote:
bf109 was small and quite thin which gave it excellent speed, but as guns etc where placed upon it stressed the wing root
stress was not as high on a spitfire as a smaller wingload by having a larger wing even if thinner allowed it to place less strain on the wingroot opposite of a smaller Bf109...each had there advantages as a smaller wing allowed less drag, but also increased it's stall speed as well as stress it would have taken attaching a landing gear or if it would have had 4 machine guns, ammunition and racks to hold this...

Quite thin but not as thin as the wing of a Spitfire!
Bf109 wing load.Wing loading: 199.8 kg/m² (40.9 lb/ft²)
Bf109 wingsize area.Wing area: 16.05 m2 (173.3 ft2)
bf109 weight Loaded weight: 3148 kg (6,940 lb)
supermarine spitfire wingload Wing loading: 24.56 lb/ft² (119.91 kg/m²)
supermarine spitfire wingsize area 242.1 ft² (22.48 m²)
supermarine spitfire Loaded weight: 6,622 lb (3,000 kg)

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Re: Why did Germany use inverted engines?

Post by Ome_Joop » 22 Apr 2009 18:47

bf109 emil wrote:
Bf109 wing load.Wing loading: 199.8 kg/m² (40.9 lb/ft²)
Bf109 wingsize area.Wing area: 16.05 m2 (173.3 ft2)
bf109 weight Loaded weight: 3148 kg (6,940 lb)
supermarine spitfire wingload Wing loading: 24.56 lb/ft² (119.91 kg/m²)
supermarine spitfire wingsize area 242.1 ft² (22.48 m²)
supermarine spitfire Loaded weight: 6,622 lb (3,000 kg)
I'm not that good with calculators but.....
24.56 x 242.1 = 5,946 lb
40.9 x 173.3 = 7,088 lb

which 109 vs which spit?
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Re: Why did Germany use inverted engines?

Post by bf109 emil » 22 Apr 2009 19:10

Ome_Joop wrote:
bf109 emil wrote:
Bf109 wing load.Wing loading: 199.8 kg/m² (40.9 lb/ft²)
Bf109 wingsize area.Wing area: 16.05 m2 (173.3 ft2)
bf109 weight Loaded weight: 3148 kg (6,940 lb)
supermarine spitfire wingload Wing loading: 24.56 lb/ft² (119.91 kg/m²)
supermarine spitfire wingsize area 242.1 ft² (22.48 m²)
supermarine spitfire Loaded weight: 6,622 lb (3,000 kg)
I'm not that good with calculators but.....
24.56 x 242.1 = 5,946 lb
40.9 x 173.3 = 7,088 lb

which 109 vs which spit?
bf109 G-6 Data from The Great Book of Fighters[145] and the Finnish Air Force Bf 109 Manual
Specifications (Spitfire Mk Vb)Data from The Great Book of Fighters[98] and Jane’s Fighting Aircraft of World War II
wingload is weight ie bf109 loaded 6940 divide by wing area 173.3 square feet = 40.04 pounds per square foot of wing
spitfire weight 6622 divided wing area of 242.1 square feet = 27.35 pounds per square foot

I believe because of the higher wingload and higher stall speed, the Bf109 was equipped with wing slats that would extend if speed dropped or a plane reached close to stall speed as well....but as others say lets keep this on topic :D

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Re: Why did Germany use inverted engines?

Post by Ome_Joop » 22 Apr 2009 21:18

a few remarks (hopefully i t's a bit clear)

Comparing a Vb with a G6 ( i guess a F-4 would be more fair or a Mk.IX vs a G-6)

I still don''t see what wingloading has to do with the stress on the wings generated on the landinggear (as the total weight has something to do with that...still it seems that both a/c could handle it as later a/c were more heavy and what about those 109 wingpod cannons?)
Stress on the wingroot and wingloading are 2 different things and putting the guns in the wings or above the engines still won't increase/decrease wingloading (as you already pointed out: wingload is loaded weight divided by wing area).

yes the 109's wingloading is higher but that still doesn't mean the wingroot is more stressed vs spitfire (as the total weight of spit wing with cannons and gear could be heavier than a 109's without those)

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Re: Why did Germany use inverted engines?

Post by bf109 emil » 22 Apr 2009 23:44

yes the 109's wingloading is higher but that still doesn't mean the wingroot is more stressed vs spitfire (as the total weight of spit wing with cannons and gear could be heavier than a 109's without those)
the load placed on a wing in terms of stress or weight is transfered directly to the wingroot...look at the Japanese zero which never had a wing root but actually had a solid wing, upon which the top of it, the pilots feet rested on the top of the wing giving it enormous strength and mobility...
In Len Deighton Battle of Britain he discusses this as well as the 109 could out turn a spitfire, but few pilots would put this extreme stress on the root, spitfire pilots had the advantage of almost what seemed like the wing would flap if excess g's where place on the wing...more so as the weight and centrifugal forces added to the stress place on the root. Original placement of the landing gear on the bf109 on the body was more of a design to allow mass producing in the smaller assembly plant and the wings being made and added later allowed a better
The wing structure was another significant departure from commonly accepted design practice at the time… instead of a full span solid spar, Messerschmitt built the fuselage of the 109 around an incredibly strong central spar section (the Holmbrücke) to which the wings themselves were attached with two very large and very strong bolts. Not only did this allow rapid repair in the event of a damaged wing, it also allowed greater use of factory space because no single production element of the 109 was greater than 20 feet long or so.
http://www.aeroplanebooks.com/forum/for ... asp?TID=20
there is also a nice comparison on how the 109 differed from the 190 in terms of structural differences and engineering variants comparing the 2 planes

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Re: Why did Germany use inverted engines?

Post by Ome_Joop » 23 Apr 2009 07:38

the load placed on a wing in terms of stress or weight is transfered directly to the wingroot...
There is an interesting point as the total load on the wings (no the wingload as that is loaded weight divided by wing area) is about the same.
Bf-109T had a bigger/longer wing for instance of 17.5 square meters (vs 16,4 m2) with the same wingroot which with your logic would actually mean that the wingroot was stressed less compared to a normal 109E flown with same weight?!

You are actually telling that because a clipped wing spitfire had a smaller wingarea (231 ft/ 21.5 m2) and therefore a higher wingloading must have a more stressed wingroot :roll:

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Re: Why did Germany use inverted engines?

Post by bf109 emil » 23 Apr 2009 08:35

Ome_Joop wrote:
the load placed on a wing in terms of stress or weight is transfered directly to the wingroot...
There is an interesting point as the total load on the wings (no the wingload as that is loaded weight divided by wing area) is about the same.
Bf-109T had a bigger/longer wing for instance of 17.5 square meters (vs 16,4 m2) with the same wingroot which with your logic would actually mean that the wingroot was stressed less compared to a normal 109E flown with same weight?!

You are actually telling that because a clipped wing spitfire had a smaller wingarea (231 ft/ 21.5 m2) and therefore a higher wingloading must have a more stressed wingroot :roll:
The T had a larger wing which allowed a slower stall speed and take off speed and was designed to be used on a carrier which never happened.
The clipped wing spitfire because of a smaller wing had less drag and was limited to lower altitude usage, a higher stall speed would have incurred. A wing is designed to create lift which is transfered to the wingroot, a smaller wing would require a greater airflow over the wing to create the same lift as a larger one

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Re: Why did Germany use inverted engines?

Post by kriegsmarine221 » 23 Apr 2009 10:44

so if a lancaster had a super top speed of lets say 2000km/h and the wings of a spitfire would it fly with the same bombload? excluding the fact that the whole thing would break up and also excluding other problems that would occur.

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Re: Why did Germany use inverted engines?

Post by bf109 emil » 24 Apr 2009 03:17

kriegsmarine221 wrote:so if a lancaster had a super top speed of lets say 2000km/h and the wings of a spitfire would it fly with the same bombload? excluding the fact that the whole thing would break up and also excluding other problems that would occur.

yes if the speed was sufficient and could be reached for take off and provided they where strong enough, look at todays planes although a bad comparison, because they have speed (jet engines in todays terms) a smaller plane with a smaller wing can carry ordanance in weight superior to say an older B-17 with a smaller wing...
look at the wingspan of over 102 feet for the Lanc or 103 foot wide wing and wing area of 1420 square feet on a slower B-17
Loaded weight: 54,000 lb (24,495 kg)
for this comparison compared to a faster F-117 Nighthawk but smaller wing span and area 43 foot wide and smaller surface area to provide lift being being 783 square foot can carry a larger bomb load
Loaded weight: 52,500 lb (23,800 kg)
because it is faster and more air going over the wing can create more lift. sorry for not comparing a Lanc with a modern RAF plane but i think comparing 2 USAF planes to demonstrate how a smaller wing but superior speed suites the questionhttp://en.wikipedia.org/wiki/B-17_Flying_Fortressvshttp://www.aviationearth.com/planes/mil ... nighthawk/
or an f-14 with superior speed# Wingspan:

* Spread: 64 ft (19.55 m)
* Swept: 38 ft (11.58 m)
Wing area: 565 ft² (54.5 m²)
Hardpoints: 10 total: 6× under-fuselage, 2× under nacelles and 2× on wing gloves[46] with a capacity of 14,500 lb (6,600 kg) of ordnance and fuel tanks
closer to the lancs bombload with a much smaller wing, provided the engine or power to propel the plane is suffice a small wing can carry an equal load unsure about a spitfire wing, but if the plane could reach enough speed to allow airflowing over the wing to provide lift, then yes even a tiny wing in theory as the spits would work provided it could be attached or engineered to withstand enourmous loads placed upon it

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Re: Why did Germany use inverted engines?

Post by bf109 emil » 24 Apr 2009 03:51

kriegsmarine221...here is a equal comparison...the 262 because of a higher speed and power could take off and fly with a much higher loaded weight then a spitfire using almost identical wing area..
spit wing area Wing area: 242.1 ft² (22.48 m²)
spits loaded Max takeoff weight: 6,770 lb (3,071 kg)
---------------------------------------------------------------
Me 262 wing area Wing area: 21.7 m² (234 ft²)
Me 262 loaded Max takeoff weight: 6977 kg (15,381 lb)
--over double the maximum take off weight both because
1.there was sufficient horsepower to propel the plane, and
-2 because of higher take off speed and flow over the wing it could carry or lift more weight....maybe an engineer could formulate say an engine with todays thrust being placed on an WW2 Me 262 could indeed lift the bombload of a Lanc, provided the wing was engineered to sustain the increase in power or strength needed

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