Why the heck did they design it that way?

Timppa · Jul 30, 2018

michael rauls said:
Those being the narrow undercarriage and limited fuel capacity. I'm sure there are many examples so " why the heck did they design it that way"

Those are easy...
Why the German V -engines were installed upside down ?

BiffF15 · Jul 30, 2018

Shortround6 said:
Getting back to the original premise of the thread, you often have to look at where a design team or airforce was coming from.

Bf 109
View attachment 503770
2 guns, fixed pitch prop (soon to be replaced) under 700hp engine was replacing
the HE 51
View attachment 503771
2 guns, fixed pitch prop, around a 700hp engine (which could be traced back to WW I) and narrow landing gear
and the Arado 68
View attachment 503772
2 guns, same basic engine as the early 109.
They were trying for for a through the prop gun on the early 109s
View attachment 503773
This plane may have had a machine gun or simply the intention of mounting one, they often malfunctioned and some were removed in service. Not sure if this plane was fitted with wing guns or not, but it does have an adjustable or controllable pitch propeller.

Narrow landing gear attached to the fuselage was what they were used to. Small fuel tanks giving an endurance of under 2 hours was what they were used to.

My guess is the 109 groundlooped on takeoff or during a go around. Right main is folded under as if the tail had swung to the right fairly violently. Large p factor not compensated for with rudder? Just a guess based on a single picture.

Also what is the small protuberance with a port in it behind the left main.

While I didn't sleep in a Holiday Inn Express last night I did attend the USAF Aircraft Mishap Investigator Course at Kirtland AFB many moons ago.

Cheers,
Biff

Reluctant Poster · Jul 30, 2018

wuzak said:
Supermarine did try and stuff more fuel into the Spitfire over the years.

But the amount they could add was limited by the space available in the airframe.

They added bladder tanks in the inner leading edge of the wings of the VIII and XIV. 17.5 proper gallons each, IIRC.

Rear fuselage tanks were added, with flight restrictions due to loss of stability when they were full.

But these required modifications to the wing, which may have been factory only mods (ie produced that way) that could not be added in the field.

The forward upper tank in the XIV was bigger than the Merlin Spitfires had. Had to move things around, such as the oil tank, to fit that.

Not true. The upper tank in a Griffon Spitfire was smaller. The original top tank was 48 imp gallons, the bottom tank was 37 gallons for a total of 85. The Mark VII increased the bottom tank size to 47 for a total of 95. The Griffon was mounted lower than the Merlin (The sighting view over the nose was actually slightly better despite the longer engine), therefore there was no room for the oil tank beneath the nose. The first batch of Mark XIIs were based on the Mark IX airframe and moved the oil tank to the rear fuselage. The last batch were based on the Mark VIII airframe and relocated the oil tank in front of the pilot. To make room the upper tank was reduced to 38 gallons, so the total went back to 85. The Mark XIV retained this arrangement.

BiffF15 · Jul 30, 2018

Timppa said:
Those are easy...
Why the German V -engines were installed upside down ?

Timppa,

I'm pretty sure it was for visibility over the nose and for weapons that fired thru the prop hub.

Cheers,
Biff

Shortround6 · Jul 30, 2018

As a wild guess I would say that the protuberance behind the left landing gear might be a gun camera?
I have no idea if it means anything but the tire on the left landing gear doesn't seem to be on the rim anymore.

BiffF15 · Jul 30, 2018

Shortround6 said:
As a wild guess I would say that the protuberance behind the left landing gear might be a gun camera?
I have no idea if it means anything but the tire on the left landing gear doesn't seem to be on the rim anymore.

I thought the same regards possible gun camera. Tire could come off the rim after being deflated due to lateral skidding (have seen the same at car accidents so only a guess).

swampyankee · Jul 30, 2018

Mili

Shortround6 said:
Getting back to the original premise of the thread, you often have to look at where a design team or airforce was coming from.

Bf 109
View attachment 503770
2 guns, fixed pitch prop (soon to be replaced) under 700hp engine was replacing
the HE 51
View attachment 503771
2 guns, fixed pitch prop, around a 700hp engine (which could be traced back to WW I) and narrow landing gear
and the Arado 68
View attachment 503772
2 guns, same basic engine as the early 109.
They were trying for for a through the prop gun on the early 109s
View attachment 503773
This plane may have had a machine gun or simply the intention of mounting one, they often malfunctioned and some were removed in service. Not sure if this plane was fitted with wing guns or not, but it does have an adjustable or controllable pitch propeller.

Narrow landing gear attached to the fuselage was what they were used to. Small fuel tanks giving an endurance of under 2 hours was what they were used to.

Timppa said:
Those are easy...
Why the German V -engines were installed upside down ?

The official answer is probably something about better pilot visibility.

The real answer is that a general turned the blueprint upside-down and everybody was afraid to correct him.

GrauGeist · Jul 30, 2018

Just for the record: Daimler-Benz, Junkers and Argus weren't the only manufacturers that designed most of their aircraft engines to be inverted.
Ranger Aircraft engines, like the L-440 and V-770 were inverted designs, too.

Shortround6 · Jul 30, 2018

The real answer is a German group of visitors to RR in the very early 30s saw a mock up of an inverted engine and promptly went home to copy it

Shortround6 · Jul 30, 2018

GrauGeist said:
Just for the record: Daimler-Benz, Junkers and Argus weren't the only manufacturers that designed most of their aircraft engines to be inverted.
Ranger Aircraft engines, like the L-440 and V-770 were inverted designs, too.

So were the British (and Czechoslovakian) in-line 4 and 6 cylinder light aircraft engines but there is another reason coming into play.

An inverted engine in a light plane can use a larger diameter prop than the same engine in an upright configuration due to the higher thrust line.
And/or better vision over the nose. Most of the light planes (and even the first Ranger V-12s) didn't use reduction gears so prop was inline with the crankshaft.

wuzak · Jul 30, 2018

As was the de Havilland Gipsy Twelve/Gipsy King.

200-300lbs less weight than a Merlin (without cooling system) as well as 700-800hp less.

GrauGeist · Jul 30, 2018

Ranger's 4 and 6 had the output at the crank, but their 12 did have a reduction gear assembly.

The V-770:

Shortround6 · Jul 30, 2018

Not all of them. They started with a direct drive version
http://rgl.faa.gov/Regulatory_and_G...171862572c0006f8ec8/$FILE/ATTD3NYA/ATC184.pdf

Please note the early ones were not supercharged either.

Wiki is wrong, the V-770 was not based on the 6-440.

Fairchild (Ranger) had made 6 cylinder 370, 390 and 410 cu in engines before building the 440. The 770 used the same bore and stoke as the 390 cu in six.
http://www.enginehistory.org/Piston/Fairchild/Fairchild.shtml

tyrodtom · Jul 30, 2018

I don't know how many people have worked on high performance engines, but a great deal of the work you do on one involves work around the heads,( valve train, spark plugs)
A inverted engines puts a lot of the work where it can be done from ground level, or from a low platform.
Imagine climbing up and down a ladder, or stepped platform, to perform maintenance task all day, it'd have to wear you down.
I've worked on some big trucks that required working platforms, that sure added to my work load.

Timppa · Jul 31, 2018

tyrodtom said:
I've worked on some big trucks that required working platforms, that sure added to my work load.

So why are these engines not upside down ?

Shortround6 · Jul 31, 2018

Because you have to get the power from the crankshaft (now top of the engine) down to near the line of the axles.
A long complicated gear train or a shaft with bevel gears at each end?

tyrodtom · Jul 31, 2018

Timppa said:
So why are these engines not upside down ?[/QU

I'm not trying to say they inverted the engines to make them easier to work on, it was just a side benefit.
After over 50 years of working on various types of engines, it's rare to see any evidence that any were engineered with ease of maintenance in mind.

GrauGeist · Jul 31, 2018

Apart from a benefit of better visability over the cowl, an inverted engine has a lower center of gravity.

pbehn · Jul 31, 2018

Don't radial and rotary engines demonstrate that there is no "right way up"?

Clayton Magnet · Jul 31, 2018

I had always assumed that an inverted engine would struggle with oil consumption, but that doesn't seem to be the case with the DB series. Did the DB engines have a better scavenge system?

Why the heck did they design it that way?

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