RHS Maneuverability Review: Data [ALL Data Done]

[ChezDaJez]

If it was your mod - how would you do it?

I would take into account where ever possible any particularly vulnerable part of an aircraft such as the tail boom on the P-38 or radiators on inline-engined aircraft. I would probably use a + / - system to rate them. Add for self-sealing fuel tanks, armor, and structural integrity. Minus for in-line engine or structural weakness such as the dive limitation for the Zero.

From what I've read, I don't think your mod is that far off from what I might have done. I just might have carried it a bit further if possible. We can quibble over things here and there but I do like the fact that you have taken into account wing-loading for maneuverability.

Chez

[Mike Scholl]

ORIGINAL: Nemo121

Well British and German wartime accounts do point to the geodesic construction as being particularly strong and giving the British bomber involved a greater ability to survive damage inflicted.

Tell that to the aircrews of the 94 British bombers shot down over Nuremburg..., greatest single Luftwaffe victory over bombers in the War. The geodesic design was inovative and successfull, but nothing in the records suggests that as implemented it had a significant effect on survivability in the manner of the Sturmovik's "steel bathtub" armor.

[Nemo121]

Scholl,

The argument you make proves nothing.

Firstly, not all of those bombers shot down had a geodesic structure.

Secondly, it is possible to argue that bombers which returned to base in a damaged condition would have been destroyed if they had not had a geodesic design. Conversely one can make the statement that more would have been shot down if they were not of geodesic design. Unprovable? Yes, in the same way as your assetion plays hard and loose with the facts.

Thirdly, I've seen several RAF debriefings in which squadron commanders etc wax lyrical about the amount of damage the bombers with a geodesic design could take and still return to base when compared to their previous bombers. So that's evidence in the record.

Fourthly, structural design textbooks clearly state that geodesic designs are stronger than spheroidal or tubular ( constant diameter tube with rounded ends... typical for most WW2 airplanes) designs. When physics and structural analysis supports it being stronger I'll believe them.

Facts make something so. Saying it is so proves nothing.


So, we have historical reports from debriefs, we have backup from physics departments around the world and we have the reality that the 94 losses over Nuremberg don't actually prove anything one way or the other. Even if, for the sake of argument, those 94 bombers had all had a geodesic design all that might mean is that non-geodesic bombers might have lost 120 bombers over Nuremberg that night.  I think it is fairly obviou that geodesic designs DID convey a durability benefit. How much is something up for discussion.

[Mike Scholl]

ORIGINAL: Nemo121

Scholl,

The argument you make proves nothing.

Firstly, not all of those bombers shot down had a geodesic structure.

Secondly, it is possible to argue that bombers which returned to base in a damaged condition would have been destroyed if they had not had a geodesic design. Conversely one can make the statement that more would have been shot down if they were not of geodesic design. Unprovable? Yes, in the same way as your assetion plays hard and loose with the facts.

Thirdly, I've seen several RAF debriefings in which squadron commanders etc wax lyrical about the amount of damage the bombers with a geodesic design could take and still return to base when compared to their previous bombers. So that's evidence in the record.

Fourthly, structural design textbooks clearly state that geodesic designs are stronger than spheroidal or tubular ( constant diameter tube with rounded ends... typical for most WW2 airplanes) designs. When physics and structural analysis supports it being stronger I'll believe them.

Facts make something so. Saying it is so proves nothing.


So, we have historical reports from debriefs, we have backup from physics departments around the world and we have the reality that the 94 losses over Nuremberg don't actually prove anything one way or the other. Even if, for the sake of argument, those 94 bombers had all had a geodesic design all that might mean is that non-geodesic bombers might have lost 120 bombers over Nuremberg that night.  I think it is fairly obviou that geodesic designs DID convey a durability benefit. How much is something up for discussion.

It's only "stronger" if the same weight of material is put into the airframe...... As I said, the Britich used the inherant strength of the design to make the airframes lighter and increase the carrying capacity or bombload......They weren't trying to build a "Flying Fortress", they wanted a "Flying Dumptruck" to place the most "bang" on target they could manage.

[Nemo121]

It's only "stronger" if the same weight of material is put into the airframe

 
Well, another way of putting that is to say that per unit weight a geodesic airframe is stronger than a non-geodesic airframe, particularly a long non-geodesic one ( such as many bombers of the time had). Sounds like a perfect case for putting an adjustment in for a geodesic airframe.
 
After all it lookes like durability takes into account the weight of the plane. So, if that is so then it stands to reason it should take account of non-weight structural factors also... geodesic structure is one of these factors and, therefore, should be taken into account.
 
You've admitted that per unit weight a geodesic frame is stronger ( more durable) so under what grounds would you now exclude something from consideration which, by your own admission, acts to make an airframe more durable?

[Mike Scholl]

ORIGINAL: Nemo121

It's only "stronger" if the same weight of material is put into the airframe

Well, another way of putting that is to say that per unit weight a geodesic airframe is stronger than a non-geodesic airframe, particularly a long non-geodesic one ( such as many bombers of the time had). Sounds like a perfect case for putting an adjustment in for a geodesic airframe.

After all it lookes like durability takes into account the weight of the plane. So, if that is so then it stands to reason it should take account of non-weight structural factors also... geodesic structure is one of these factors and, therefore, should be taken into account.

You've admitted that per unit weight a geodesic frame is stronger ( more durable) so under what grounds would you now exclude something from consideration which, by your own admission, acts to make an airframe more durable?

I'll try to explain this one more time. If the airframe requirements using a more traditional design were five tons of aluminum, and you put the same five tons of aluminum into an inherently stronger Geodesic Design, you would have a stronger airframe. BUT, since aluminum was a "strategic material" in high demand and short supply, you ALSO have the choice to use just four tons of aluminum in the stronger design, and get an airframe that is just as strong, but ONLY just as strong, as the traditional design; but saves you a ton of aluminum and lets you carry 2,000 lbs. more bombload. In this case the A/C does not deserve any durability "bonus" for it's design---because it already got it's bonus in the bigger bombload. Get it?

[witpqs]

So (in that case) you took advantage of the stronger design to
a) save material
b) carry more weight

You gave up the chance to build a stronger airplane, instead opting for a and b (above).

Right?

[Nemo121]

I understand what you are saying but I think you aren't open to seeing my contention. let me put explain it:

1. Durability in WiTP is, at least in part, a function of aircraft weight. Light Japanese fighters without armour are less durable than heavier Japanese fighters without armour. twin-engined planes are more durable than single-engined, four-engined are more durable than twin-engined. So far it all follows weight.

2. A 4 ton geodesic plane is MORE durable than a 4 ton non-geodesic design. For the sake of argument let us assume a 4 ton geodesic design should have the same durability as a 5 ton non-geodesic design.

Now if I design a plane with engines which can push 6 tons through the air at the required speed and to the required range I can build a 4 ton geodesic plane carrying 2 tons of bombs, a 5 ton geodesic plane carrying 1 ton of bombs or a normal plane carrying 1 ton of bombs...

The durabilities of the 4 ton geodesic and 5 ton normal will be the same, despite the differing bomb loads. The durability of the 5 ton geodesic will be higher than the 5 ton normal.

End result.... Talking about bombload is a design decision and an irrelevance when discussing the issue of durability ratings vis a vis ( non-bombed, non-fuelled) weight and structure.


The  weight of the plane without bombload and fuel is freely available and, logically, the correct weight to use in determining durability. So, since we're using a non-bombed, non-fueled weight ( since it is plainly ridiculous to assume that a 1 ton plane carrying 9 tons of bombs and fuel would have the same durability as a 9 ton plane carring a ton of bombs and fuel) to determine durability then there IS every reason to apply a modifier for structure.

I know you have issues with accepting other's views but seriously a plane weighing x tons using a structural design feature which physics says are superior to those used in most planes IS going to have a higher durability ( aka resistance to structural failure ) than a "normal" plane of weight x. That's just common sense and an application of fact and reason to this situation.


Are you really trying to say that a 2 four ton ( non-bombed, non-fueled) planes should have the SAME durability in this game even if one is made using a design which every structural engineering student will tell you gives greater structural strength ( aka resistance to damage aka durability) than the other? That's nonsensical no matter how you argue it and no matter how you represent it we ARE discussing whether or not a given structural design grants greater durability PER UNIT WEIGHT.

[witpqs]

ORIGINAL: Nemo121

... I think you aren't open to seeing my contention.

...

I know you have issues with accepting other's views ...

Actually, this is the first time I've seen you explain clearly what you mean. I doubt it's a lack of openess.

I know you're speaking to Mike, but I thought a 3rd party viewpoint might be helpful. [8D]

What you are saying makes some sense. There is still one question - even though the geodesic shape is pound-for-pound stronger, does it actually resist damage in proportion to its additional strength? Explaining what I mean, a classic arch is very strong, but if the keystone goes the whole thing falls in a heap. Does the geodesic shape of the aircraft have the same vulnerability in that due to the continuous shape of the structure all of the pieces are, in effect, 'keystones'?

BTW, I am asking because I don't know, I am not arguing one way or the other.

[Nemo121]

Well, I've had previous conversations with him where it was difficult to account for his failure to actually take on board any point I made. That is, however, a personal perception but one based on his failure to take on board a single point I made in a few separate but concomittant threads ( sufficient for it to be a definite pattern)... That's why I usually just avoid threads he is in. OTOH I am interested in RHS and thus I posted here.
 
 
As to your point re: geodesic design... No, as far as I am aware the fuselage having a geodesic shape does not cause it to weaken excessively per unit of surface area damage ( one of the most important easily calculable means of determining how close a metallic-airframed plane is to structural failure). In fact since the Wellington and others were structurally stronger than they would have been with the normal cigar tube shaped fuselage the point was repeatedly made that a cannon shell explosion which damaged a given surface area of the outer surface was far less likely to bring a geodesic-fuselaged plane down than a cigar tube-shaped plane.
 
Obviously we need to differentiate between early types of planes which gained their structural integrity due to their internal structure and mostly had fabric stretched over said fuselage ( which were often highly resistant to damage unless said damage occurred at a structural weak point... rare in the era of machineguns but increasingly common when explosive cannon shells entered the mix) and those planes which gained much of their strength from their actual fuselage structure ( becoming more common as planes moved to metallic fuselages). This does point to the need to rate differing designs differently with respect to the exact same weapons system but such modelling falls outside of the scope of this game as there is no code or work-around way to effect such modelling.
 
 

[Mike Scholl]

ORIGINAL: witpqs

So (in that case) you took advantage of the stronger design to
a) save material
b) carry more weight

You gave up the chance to build a stronger airplane, instead opting for a and b (above).

Right?

RIGHT! The initial discussion concerned giving two specific designs a "bonus" in durability because of specific, unusual design factors. I suggestted that while the Il-2 deserved this because of the heavily armored "bathtub' surrounding it's engine and pilot, the British "geodesic" bombers did not. Because the British had chosen to use the inate strength of the geodesic design to lighten the airframe and increase the bombload. Take the armor off the Sturmovik and it could carry more bombs and cannon to attack with---but it would be just as vulnerable as any other low-flying aircraft to enemy fire (and not deserving of any "bonus"). Leave it on, and you deserve a "special bonus" to the A/C's durability/defense---but you can't hit as hard.

The British opted to use the geodesic design to lighten the airframe and increase the payload. So while the geodesic design allows the POSSIBILITY of stronger and more survivable A/C, it was not the design choice the Brits made. They opted to carry more "offensive payload" instead, settling for a design that had no more "intrensic strength" than a more conventially designed bomber of greater weight and less payload. Which would not qualify for any "special bonus" to the A/C's durability/defense. Nemo wants to give them both, I'm saying you get one or the other. That's what the discussion is about.

[el cid again]

ORIGINAL: Mike Scholl

ORIGINAL: el cid again

Nope - no bonus in maneuverability for any plane. But there is a special bonus for a Russian bomber and a British bomber in durability. The Russian one has a cast armor forebody. The British one has geodesic construction.

The Sturmovik certainly deserves a "special" consideration..., even the Germans called it a flying tank. But I don't thing the Brits should get an "edge" for the Wellington/Lancaster/whatever. The geodesic construction was stronger, but the Brits used it to lighten the overall aircraft and increase bombload (show me another bomber that can carry an 11-ton "Grand Slam" bomb)......When the Germans could find them in the dark, British bombers went down at a depressing rate.

I think the plane is the Wellington. It is a twin engine bomber whose exploits and return with battle damage are legon.
It was clear in review of the history of the aircraft it was not in the same leage as other planes of similar size. Being a two engine plane, it does not get the four engine bonus however. So it isn't actually as "durable" as a lancaster. But it is more durable than any other 2 engine aircraft rated. By about two points (under the regime that we are using a K of 2 each point ends up being two in the final value).

[el cid again]

ORIGINAL: ChezDaJez

If it was your mod - how would you do it?

I would take into account where ever possible any particularly vulnerable part of an aircraft such as the tail boom on the P-38 or radiators on inline-engined aircraft. I would probably use a + / - system to rate them. Add for self-sealing fuel tanks, armor, and structural integrity. Minus for in-line engine or structural weakness such as the dive limitation for the Zero.

From what I've read, I don't think your mod is that far off from what I might have done. I just might have carried it a bit further if possible. We can quibble over things here and there but I do like the fact that you have taken into account wing-loading for maneuverability.

Chez

As we are learning once again redoing maneuverability - 249 types is a LOT of calculation and data entry. But in principle we always are willing to use better values - if someone figures them out.

[el cid again]

Having worked in SILs (Software Integration Laboratories) which simulate aircraft and missile flights in conditions not possible in real life - and long before they are ever built - I must side with Nemo: in principle the geodesic structure is probably a better investment, pound for pound, than a armored structure like the Sturmovic had. Clearly both were in a different league for durability than normal structural methods - and that is all the RHS rating says. It is a crude indicator - worth 1 point in the calculation - and 2 points at the end (after the constant 2 - derived from calibration tests - is applied).

[el cid again]

ORIGINAL: witpqs

ORIGINAL: Nemo121

... I think you aren't open to seeing my contention.

...

I know you have issues with accepting other's views ...

Actually, this is the first time I've seen you explain clearly what you mean. I doubt it's a lack of openess.

I know you're speaking to Mike, but I thought a 3rd party viewpoint might be helpful. [8D]

What you are saying makes some sense. There is still one question - even though the geodesic shape is pound-for-pound stronger, does it actually resist damage in proportion to its additional strength? Explaining what I mean, a classic arch is very strong, but if the keystone goes the whole thing falls in a heap. Does the geodesic shape of the aircraft have the same vulnerability in that due to the continuous shape of the structure all of the pieces are, in effect, 'keystones'?

BTW, I am asking because I don't know, I am not arguing one way or the other.

The great advantage of a geodesic structure is it does not matter where the damage occurs - the structure retains integrity until a very large number of structural points are defeated. The only thing that matters is if you hit something or someone vital (a pilot, an engine) - if you don't - even hitting and destroying a structural point matters almost not at all. Most aircraft have very vital structural members - geodesic airplanes have very few of these. The whole skin is laced with structural cables - an loss of a few is not particularly meaningful.

[Herrbear]

Something I just thought of concerning the dividing by the number of engines. Now that Wing Loading and Power Loading is taken into account do you penalize multi engine planes for speed and ROC. Wouldn't all planes, in theory, be consistent for those two factors. For example, shouldn't a 2-engine plane with 1000 hp engines with a ROC of 3000 and weight of 10,000 lbs work the same as a 1-engine plane with a 2000 hp engine also with a ROC of 3000 and a weight of 10,000 lbs.

Why would the 2-engine plane be penalized in those factors?

[witpqs]

Except for the case of multiple engines along the center axis (very rare), multi-engine planes in WWII have their engines on/in the wings. Because the engines are heavy, this means that they have a lot more inertia to overcome when they try to roll. It's basically the physics concept of angular momentum.

This is one big difference between single and multi-engine planes in WWII.

[el cid again]

ORIGINAL: Herrbear

Something I just thought of concerning the dividing by the number of engines. Now that Wing Loading and Power Loading is taken into account do you penalize multi engine planes for speed and ROC. Wouldn't all planes, in theory, be consistent for those two factors. For example, shouldn't a 2-engine plane with 1000 hp engines with a ROC of 3000 and weight of 10,000 lbs work the same as a 1-engine plane with a 2000 hp engine also with a ROC of 3000 and a weight of 10,000 lbs.

Why would the 2-engine plane be penalized in those factors?

The multi engine penalty - it is not just for twin engine planes - but all of them - is meant to address the problem of conservation of angular momentum. It is meant to say that it is a severe restriction on maneuverability. It is a nice part of the function - whatever the number of engines - it goes there. There is, however, this caviet: multiple engines on one axis count as one engine. This can occur in 3 ways (and does NOT occur in WITP so far).

1) Two engines coupled to act as one.
2) Two engines with a common shaft - driving counter rotating screws on the same hub.
3) Two engines on a single axis - one driving a tractor and one a pusher.

Anyway - the number of engines is in the deonominator because that is the right place for it to be. It divides what otherwise would be the maneuverability value - a composite function - by N. It is not meant to say any particular element of that function is so divided.

[Herrbear]

ORIGINAL: witpqs

Except for the case of multiple engines along the center axis (very rare), multi-engine planes in WWII have their engines on/in the wings. Because the engines are heavy, this means that they have a lot more inertia to overcome when they try to roll. It's basically the physics concept of angular momentum.

This is one big difference between single and multi-engine planes in WWII.

I understand about the concept of angular momentum. But I am only discussing max speed and rate of climb. I don't think that angular momentum plays a part in this.

[Herrbear]

ORIGINAL: el cid again

ORIGINAL: Herrbear

Something I just thought of concerning the dividing by the number of engines. Now that Wing Loading and Power Loading is taken into account do you penalize multi engine planes for speed and ROC. Wouldn't all planes, in theory, be consistent for those two factors. For example, shouldn't a 2-engine plane with 1000 hp engines with a ROC of 3000 and weight of 10,000 lbs work the same as a 1-engine plane with a 2000 hp engine also with a ROC of 3000 and a weight of 10,000 lbs.

Why would the 2-engine plane be penalized in those factors?

The multi engine penalty - it is not just for twin engine planes - but all of them - is meant to address the problem of conservation of angular momentum. It is meant to say that it is a severe restriction on maneuverability. It is a nice part of the function - whatever the number of engines - it goes there. There is, however, this caviet: multiple engines on one axis count as one engine. This can occur in 3 ways (and does NOT occur in WITP so far).

1) Two engines coupled to act as one.
2) Two engines with a common shaft - driving counter rotating screws on the same hub.
3) Two engines on a single axis - one driving a tractor and one a pusher.

Anyway - the number of engines is in the deonominator because that is the right place for it to be. It divides what otherwise would be the maneuverability value - a composite function - by N. It is not meant to say any particular element of that function is so divided.

Sid -- I understand why the penalty is used as it impacts wing loading and power loading. But does the "problem of conservation of angular momentum" have any impact on max speed or ROC. If it doesn't, why penalize those factors?