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Redwulf__26
01-06-2006, 04:46 AM
Here's one for the engineers.

Why were the Allied inline engines such as the RR Merlin and Griffon, the Allison variants and also the Russian Klimov, designed in an upright V configuration. Whereas the German DB and Jumo engines were inverted V ?
Anyone like to postulate a theory, if thats what you do with theories. http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

Redwulf__26
01-06-2006, 04:46 AM
Here's one for the engineers.

Why were the Allied inline engines such as the RR Merlin and Griffon, the Allison variants and also the Russian Klimov, designed in an upright V configuration. Whereas the German DB and Jumo engines were inverted V ?
Anyone like to postulate a theory, if thats what you do with theories. http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

WOLFMondo
01-06-2006, 05:33 AM
Maybe something to do with the German engines being fuel injected whereas the Allison and Merlin were not?

msalama
01-06-2006, 05:55 AM
Hey, that's a good question... anyone?

-HH- Beebop
01-06-2006, 06:00 AM
WOLFMondo has it right. Rolls and allison engines were gravity fed carburated engines. If they had been installed upsidedown all the fuel would have just leaked onto the ground.
DB's and Jumos were injected under pressure. It didn't matter what their orientation was.

stathem
01-06-2006, 06:17 AM
Hmm, I dunno. Although fuel injection would be neccessary for the inverted Vee I doubt it was the reason they were that way.

I reckon it might have been something to do with providing a better view over the nose.

Incidently one the British companies also had a pre-war inverted Vee motor.

Edit - The De Havilland Gypsy and Cirrus series

p-11.cAce
01-06-2006, 06:20 AM
the orientation of the cylinders does not matter - injected engine or not. It is hte orientation of the carb that matters. If this were not the case how would carbed radial engines run? Half their cylinders are flat or inverted and they run just fine. I always thought the German engines were inverted to make space for the guns in the fwd fuelage. Whatever the reason a carb fed piston engine will run just fine regardless of its cylinder orientation as long as the carb remains upright.

jimDG
01-06-2006, 06:29 AM
took 2 sec with google:
search key: "inverted daimler benz"
first result:
http://en.wikipedia.org/wiki/Daimler-Benz_DB_605

stathem
01-06-2006, 06:31 AM
Another one - does it allow a better (higher) line of propshaft without the need for a gearbox?

Capt.LoneRanger
01-06-2006, 07:19 AM
No engine uses fuel that dribbles into the cylinders, not even a Diesel-engine. http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif


The inverted system has several advantages:

- the prop-axle is located higher
=> better rolling characteristics
=> better visibility for the pilot
=> shorter landing gear
=> lower barycenter
=> better ground handling
- easier to maintain

IIRC it is also easier to cool the engine with fluid systems and for the oil-circuits.

Dash_C.
01-06-2006, 12:08 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by stathem:
Another one - does it allow a better (higher) line of propshaft without the need for a gearbox? </div></BLOCKQUOTE>

This was my first thought...

Edit: From JimDG's link: "The inverted mounting of the cylinders provided better visibility for the pilot, a lower center of gravity, and improved access for maintenance."

http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

tomtheyak
01-06-2006, 12:14 PM
not sure if the porp shaft higher arguement is a good one - after all, the DB engined 109 vs the Merlin engined Buchon, the daimler motor has far lower thrustline, and I'd be surprised if they didnt gear down the prop considering the crankshaft is at the top of the motor in an inverted V - the motor would have to run at a very slow rpm to be directly connected to the prop!

Choctaw111
01-06-2006, 12:29 PM
What about leaving more room for the guns over the nose? The Germans loved having concentrated firepower. Take a look at most of their designs. They didn't want to be bothered with convergence when they didn't have to. It seems to me that putting the engines in this way gave them more room on top for better pilot view and bigger guns at the same time. How many Allied fighters had guns in front of the pilot? Well, I guess the P39 did but look at where the engine is on that one. There was plenty of room up front. Anyway that is just a thought that I had.

LameDuck.
01-06-2006, 01:06 PM
Hhhmmm, makes me wonder about oiling. Do the inverted Vees use a dry sump system?
Neat question Redwulf http://forums.ubi.com/images/smilies/25.gif

LStarosta
01-06-2006, 01:26 PM
It has been also said that Germans installed their radial engines upside down.

JG7_Rall
01-06-2006, 02:52 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by LStarosta:
It has been also said that Germans installed their radial engines upside down. </div></BLOCKQUOTE>



Not only that, but they also installed their gunsight so far over so that no one can use it; it's no wonder they lost the war

LStarosta
01-06-2006, 02:53 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JG7_Rall:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by LStarosta:
It has been also said that Germans installed their radial engines upside down. </div></BLOCKQUOTE>



Not only that, but they also installed their gunsight so far over so that no one can use it; it's no wonder they lost the war </div></BLOCKQUOTE>

http://forums.ubi.com/images/smilies/35.gif

Flakwalker
01-06-2006, 03:01 PM
Yes, as stated above, it allowed a better room usage to include fuselage guns on top of the nose. For example the A-36 apache had the nose mg under the engine for that reason.
About the radial I have no idea, but in fact, is not the same? http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

LStarosta
01-06-2006, 03:02 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Flakwalker:
About the radial I have no idea, but in fact, is not the same? http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif </div></BLOCKQUOTE>


Nooooo... reaaaallly?

http://forums.ubi.com/images/smilies/16x16_smiley-tongue.gif http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

Taylortony
01-06-2006, 05:37 PM
[QUOTE]Originally posted by -HH- Beebop:
WOLFMondo has it right. Rolls and allison engines were gravity fed carburated engines. If they had been installed upsidedown all the fuel would have just leaked onto the ground.
QUOTE]

To blow this one firmly out of the water..... The Peregrine or kestrel Engine the predecessor of the Merlin was a V12 they took 2 of these turned one upside down and cobbled them together in a common Crankcase to form the V24 X configuration Vulture which was used in the ill fated Manchester, the twin engined precursor to the Lancaster, the engines sucked so were ditched and the Manchester was reworked to carry 4 Merlins and the Lancaster was born http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Taylortony
01-06-2006, 05:55 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by LameDuck.:
Hhhmmm, makes me wonder about oiling. Do the inverted Vees use a dry sump system?
Neat question Redwulf http://forums.ubi.com/images/smilies/25.gif </div></BLOCKQUOTE>

yes so does the griffin it has a seperate oil tank

p1ngu666
01-06-2006, 11:24 PM
the merlin was going tobe inverted, but aircraft manufactures wanted it the right way up.

i surpose its perhaps easier to maintain a inverted in some ways, but i bet things fallin out gettin annoyin quickly

Viking-S
01-07-2006, 12:23 AM
Some pics of a DB 605 in Malmsl├┬Ątt Museum.
You can see the hole for the canon in the rear end.

http://img.photobucket.com/albums/v125/F16_fatboy/396448d2.jpg

http://img.photobucket.com/albums/v125/F16_fatboy/PICT0052.jpg

http://img.photobucket.com/albums/v125/F16_fatboy/PICT0051.jpg

LEBillfish
01-07-2006, 12:40 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Taylortony:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by LameDuck.:
Hhhmmm, makes me wonder about oiling. Do the inverted Vees use a dry sump system?
Neat question Redwulf http://forums.ubi.com/images/smilies/25.gif </div></BLOCKQUOTE>

yes so does the griffin it has a seperate oil tank </div></BLOCKQUOTE>


I'd "think" all would as a "below the crank" "pan" if you will would mean the second the plane rolled the "pan" would empty probably swamping the bearings yet starving the rest of the engine........Even extreme side to side or up & down due to turbulance might do this.

So a tank is the only option.

LEBillfish
01-07-2006, 12:42 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by p1ngu666:
the merlin was going tobe inverted, but aircraft manufactures wanted it the right way up.

i surpose its perhaps easier to maintain a inverted in some ways, but i bet things fallin out gettin annoyin quickly </div></BLOCKQUOTE>

IMLTHO it would be harder in that on the crank side there is little to nothing to service......Head side expecting they had solid/mechanical tappets or similar would mean regular service.

LameDuck.
01-07-2006, 04:58 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by LEBillfish:
I'd "think" all would as a "below the crank" "pan" if you will would mean the second the plane rolled the "pan" would empty probably swamping the bearings yet starving the rest of the engine........Even extreme side to side or up & down due to turbulance might do this.

So a tank is the only option. </div></BLOCKQUOTE>
Yeah, that occured to me after I posted. I guess I was thinking about scavenging. Looking at Viking-S's third pic (http://img.photobucket.com/albums/v125/F16_fatboy/PICT0051.jpg) of the DB605, how does it scavenge the oil from the main bearings? In simple terms, it seems the cylinders would quickly fill with oil!
http://forums.ubi.com/images/smilies/blink.gif

Viking-S
01-07-2006, 08:50 AM
The oil that finds it way past the rings on the pistons will normally be negligent but the risk that the combustion chamber is filled with oil or petrol is probably one reason why the propeller always is turned by hand a revolution or more before the attempt to start the engine
Oil from the upperparts of the DB 605 will find its way down to the lowest part of the engine, witch is the rocker covers, and there it will be sucked away to the circular storage tank located behind the spinner. The volume of the tank, 50liter, is beyond doubt calculated to be able to feed the engine even during normal dog fighting when up is sometimes down and it is harder to evacuate the return oil from the engine.
The piston engine development during this time is extremely interesting.

Next week I will get a scanner and will post a cutaway drawing of a DB601.

Viking

Sergio_101
01-07-2006, 04:40 PM
Reason for inverted V designs vary.
Service issues, streamlining and thrust CL
issues, and cooling.

advantages for inverted V.
Service, not such a big deal in a fighter
but there is less need for servicing stands.

Thrust CL. Places the thrust CL more close to
the cl of mass on the longitudal plane in a
geared engine installation.

Streamlining/drag. The widest point is at the
point of the wing root, makes for a nice transition
of the wing fillets.

Cooling, places all the plumbing on the bottom of the
plane where the radiators are. Also gravity
keeps the coolant in the most critical areas,
in particular in the heads (around the exhaust valves).

Pilot vision.

Inverted V disadvantages.

Oil and fuel collects in the combustion chambers
just as in a Radial engine.

Oil and fuel puddling in the intake manifold.
Even in fuel injected engines this is a problem
at shut down.

Oil scavenging is far more complex.


So the advantages are weak and the disadvantages
are all about the oiling system.

I see no practical disadvantages or advantages
of either design except the quick starting
advantages for the upright V.

I have had to pull the bottom spark plugs from a
radial engine to drain the oil after a failed
attempt at walking the prop.
Oil does in fact collect in the bottom cylinders
combustion chambers.



Yes, inverted Vs are dry sump.


Sergio

Taylortony
01-07-2006, 06:27 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by LEBillfish:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Taylortony:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by LameDuck.:
Hhhmmm, makes me wonder about oiling. Do the inverted Vees use a dry sump system?
Neat question Redwulf http://forums.ubi.com/images/smilies/25.gif </div></BLOCKQUOTE>

yes so does the griffin it has a seperate oil tank </div></BLOCKQUOTE>


I'd "think" all would as a "below the crank" "pan" if you will would mean the second the plane rolled the "pan" would empty probably swamping the bearings yet starving the rest of the engine........Even extreme side to side or up & down due to turbulance might do this.

So a tank is the only option. </div></BLOCKQUOTE>


you have a oil air seperator and the simple expediancy of fitting a flexible hose in the sump and baffling negates the need when inverted of oil starvation as the flexy hose will find the oil when inverted