Centauro fighter

[Tante Ju]

Have to disagree with you on that. Its like saying that it could dogfight with an 215 kg bomb.

Its not a good analogue. Fighting with gondolas does not have nearly same effect fighting with 215 (250kg) bomb.

The weight addition may same, but result drag from a 250 kg bomb is far more than gondolas - some 40 km/h as I know compared to 8.
It is the extra drag that reduces turn ability, climb etc not the extra weight (extra weight only very slightly adds drag due to increased incidence needed).

So a gondola with very little extra dreg reduces climb, turn etc. very little, a similiar weight bomb in comparison is very serious reduction.

There are detailed figures for 109 G at kurfurst seite. Kurfürst - Leistungzusammenstellung Me 109 G.

In fact its worse as the weight is out on the wings well away form the COG.

That does not make sense to me. How is the same weight of two wing MG 151 worse in 109G than in G-55? Or any other fighter with wing gun, say 190, Spitfire, P-47 etc? You have to explain.

 

[krieghund]

Go here for the German tactical trials comparing the Luftwaffe`s Bf 109G-4 and FW 190A-5 to contemporary Italian types Macchi 205 V, Macchi205 N, Reggiane 2005 and Fiat G 55.

http://www.ww2aircraft.net/forum/fl...an-guidonia-test-centre-33001.html#post907715

 

[Glider]

Its not a good analogue. Fighting with gondolas does not have nearly same effect fighting with 215 (250kg) bomb.

The weight addition may same, but result drag from a 250 kg bomb is far more than gondolas - some 40 km/h as I know compared to 8.
It is the extra drag that reduces turn ability, climb etc not the extra weight (extra weight only very slightly adds drag due to increased incidence needed).

I agree about the drag but weight does have an effect, also the position of the weight has an impact. By adding the extra weight out on the wings you impact the time taken to roll the aircraft, and as you know you have to roll before you can turn. The weight impacts the actual turn as the forces of greater. Climb is a serious problem as all things being equal, weight is critical to climb. Acceleration is impacted by weight.

So a gondola with very little extra dreg reduces climb, turn etc. very little, a similiar weight bomb in comparison is very serious reduction.

The weight increases the climb, turn and general handling. The aerodynamic gondola limits the damage in max speed but everything else is impacted. Why do you think designers go to such lengths to save weight?

That does not make sense to me. How is the same weight of two wing MG 151 worse in 109G than in G-55? Or any other fighter with wing gun, say 190, Spitfire, P-47 etc? You have to explain.

Simply because the 109 wasn't designed for the weight in the wings, the other aircraft were. Its a significant change in the weight distribution to the basic design. Even here you sometimes find examples of guns sometimes being removed to try to improve performance in particular two or sometimes all four of the LMG's in Spits.
When you add weight to a basic design there is an impact. For example the Fw 190 could and sometimes did carry extra guns but there was an impact and the increased firepower was the exception not the rule. Same with the Spitfire many of which could carry 4 x 20mm, it was incorporated into the design of the wing and didn't involve any gondolas or changes, but again it was the exception not the rule because of the weight.

 

[Tante Ju]

I agree about the drag but weight does have an effect, also the position of the weight has an impact. By adding the extra weight out on the wings you impact the time taken to roll the aircraft, and as you know you have to roll before you can turn. The weight impacts the actual turn as the forces of greater. Climb is a serious problem as all things being equal, weight is critical to climb. Acceleration is impacted by weight.

Yes but all these changes are only indirectly effected by weight. Weight changes (increases) the induced drag. Since induced drag is more prominent in total drag at lower speeds, climb and turn is more seriously effected than speed.

For example Soviet test show 109G with three guns turned in 20 secs, with five guns 22 secs. Worse, yes. Worse than other? Well, Fw 190 turned 23-24 secs, Mustang I was similiar to 190, and P-47 some 28 secs... conclusion is that the overall manuverability of 109G with five guns did not change much and could easily dogfight these aircraft as before.

There were some other which turned better, say in 18 secs like Yakovlevs, Spitfires or Lavochkins. I do not think gondolas changes much in this regard for example. They already turned better for example. Overall picture - does not change. Dogfight was not recommended with light 109 either against these types.

The weight increases the climb, turn and general handling. The aerodynamic gondola limits the damage in max speed but everything else is impacted. Why do you think designers go to such lengths to save weight?

Yes but in the end its total weight that is matters. Even with Gondolas in 109 you have still lighter fighter than most other with equal or more horsepower. Heavier planes with heavy armament could still not compete with 109 in areas (say turn, climb) they could not before, like four cannon Tyhoon or Fw 190.

Simply because the 109 wasn't designed for the weight in the wings, the other aircraft were.

May I ask: how were these aircraft specific 'designed' for weight in the wing? Was the centre of gravity different? Was their stability characteristics different because of this? Controls different? In the end, what was different?

Its a significant change in the weight distribution to the basic design.

Takeing look at drawings shows the gondolas are mounted near or at the centre of gravity of 109 (fuel tank). So basic handling like pitch couldn't change. Could inertia effect yawing for example? Yes this is probable, but thing like this can be compensated by iincreased rudder size that was incorporated into 109.

How do you think weight distribution changes and what precise differences did it make? Did it shift CoG for example?

Even here you sometimes find examples of guns sometimes being removed to try to improve performance in particular two or sometimes all four of the LMG's in Spits.

No doubt removing weight from aircraft will improve performance. Question is, does it worth it. In case of LMG removal from Spits, I only read it was desperate measure to intercept JU 86 P/R. Spitfire ceiling was simply not enough, so everything had to be thrown out to make it lighter. Reason it did not become commonplace is that generally climbing to 14 000 m was not giving you any practical advantage 99% of time.

When you add weight to a basic design there is an impact. For example the Fw 190 could and sometimes did carry extra guns but there was an impact and the increased firepower was the exception not the rule. Same with the Spitfire many of which could carry 4 x 20mm, it was incorporated into the design of the wing and didn't involve any gondolas or changes, but again it was the exception not the rule because of the weight.

I agree of course adding weight adds impact. I disagree that it made the aircraft useless for air combat or any measurably less competitive. It just transitioned the 109 into a heavier 190, essentially, as far as general performance goes. Less turn, less climb, more guns.

 

[Shortround6]

I believe the Russian tests were done at a relatively low level?

The is a short section on "America's Hundred Thousand" that lists some of the changes in the performance of a P-51D with the addition of 1000lbs , all internal so the only increase in drag is the induced drag due to lift. AT WEP it is supposed to have lost 3mph (5KPH) altitude not give. I believe the loss in rate of climb was 390 to 560fpm, again altitude not given and that is the important one. It is because that loss of climb rate is at ALL altitudes. loosing 450-500fpm at low level where the climb rate maybe 3500fpm isn't that big a deal (14% ?) Loosing 500fpm at 28,000ft where the climb rate is 2000fpm is a much bigger deal. (25% ?)
I don't have th ebook infront of me at the moment but the loss of service ceiling was given I believe. This in it self is not important as only the rarest of combats took place any where near an airplane's service ceiling. However this loss of climb rate affects the planes operational ceiling, the ability of a group of planes to fly in formation. In one of the Spitfire/JU 86 intercepts there were two Spitfires but one was not able to keep formation with the other. This will move down several thousand feet also. AnotherBUT few combats took place at this altitude either. A climb rate of 500pm (2.52meters/sec) doesn't really offer a lot in the ability to recover from a maneuver. It doesn't even offer much in the way of sustaining altitude in a moderate turn like 1.5-2 "G's.

we have a question or difference of opinion. On one side we have people who say the the gondola equipped 109s suffered only a very small loss of performance and have a test result or two to back that up in terms of straight line flight and a low altitude turn test. On the other hand we have people ( including German pilots) who claim (said) that there was a big difference in the way the plane acted/performed when fitted with gondola's with out giving much in the way of numbers. It does seem that production an use of the gondola's was phased out well before the war ended and popular histories "claim" that the gondola equipped aircraft needed to be escorted or given top cover by non-gondola equipped aircraft.
How do we resolve these discrepancies?
My own opinion is that the gondola's didn't affect straight line speed much and at low altitude the plane may have had the power and lift to perform a 360 turn taking only 10% longer than a 3 gun fighter.
The problem comes in fighting the USAAF at 22,000-30,000ft. The bombers were flying at 20,000-25,000ft. The Germans need at least that height to attack from if not 2-5,00ft higher (up to 30,000ft) when the escorts show up those heights can get pushed up another few thousand feet. The 109F and early Gs without N20 had engines with critical altitudes below 20,000ft. and while they held their power fairly well in the mid 20,000ft range things were getting a bit iffy in the high 20,000 or 30,000ft range.

One test report for an early 109 G (3 gun) has it taking 2.8 minutes to go from 6000 meters to 8000 meters which is an average climb rate of 2537fpm. however at these altitudes the climb rate can be falling off rather sharply as shown by the figures for a MK V Spitfire which averages 1875fps for the climb from 20,000ft to 26,000ft. Rate of climb at 20,000ft is 2300fpm while the rate of climb at 26,000ft is 1520fpm. If the Spit climbs another 2,000ft the climb rate falls to 1240fps. The use of the Spitfire numbers is because I can't find good 109 numbers at the moment. I do hope you get the idea though. A 300-400fpm reduction in climbing ability at the 25,000-30,000 level lowers the planes combat ability by several (2-3) thousand feet. This is the primary engagement altitude for Luftwaffe fighters vs US escort fighters. Yes fights did take place above and below this.
We also have the question as to why the Luftwaffe stopped with 5 gun fighters if they were effective with little or no loss in performance? Shortage of guns? Or shortage of flight performance?

 

[Glider]

Yes but all these changes are only indirectly effected by weight. Weight changes (increases) the induced drag. Since induced drag is more prominent in total drag at lower speeds, climb and turn is more seriously effected than speed.

Weight has nothing to do with the induced drag. Its to do with the flow of the air over the wings.

For example Soviet test show 109G with three guns turned in 20 secs, with five guns 22 secs. Worse, yes. Worse than other? Well, Fw 190 turned 23-24 secs, Mustang I was similiar to 190, and P-47 some 28 secs... conclusion is that the overall manuverability of 109G with five guns did not change much and could easily dogfight these aircraft as before.

I don't know these tests but would be very interested to know at what speed they were undertaken. As I understand it at speeds up to 250 mph a clean 109 has all the advantages in a turn against a Mustang, between 250 - 350 there is nothing in it, at over 350 all the pluses are in the hand of the P51. Its a similar story with aircraft such as the Tempest. With the extra weight I would expect these bands to reduce and they do. The pilot who flew it in combat quoted a best speed of 250KPH. Now if you want to fly in combat at 250 KPH be my guest.

Yes but in the end its total weight that is matters. Even with Gondolas in 109 you have still lighter fighter than most other with equal or more horsepower. Heavier planes with heavy armament could still not compete with 109 in areas (say turn, climb) they could not before, like four cannon Tyhoon or Fw 190.

Turn maybe but in climb I am certain that it would make a significant difference. Apart from the weight the gondolas would impact the aireflow under the wing, reducing the efficiency of the wing, therefore impacting the lift and climb

May I ask: how were these aircraft specific 'designed' for weight in the wing? Was the centre of gravity different? Was their stability characteristics different because of this? Controls different? In the end, what was different?

Takeing look at drawings shows the gondolas are mounted near or at the centre of gravity of 109 (fuel tank). So basic handling like pitch couldn't change. Could inertia effect yawing for example? Yes this is probable, but thing like this can be compensated by iincreased rudder size that was incorporated into 109.

The Gondolas were mounted on the wing nowhere near the Cog. This weight on the wing would impact the rolling moment which in turn impacts the rate of roll and therefore the ability to make a turn. In short the plane will feel more slugish, it will feel heavier on the controls as the wing has to lift the weight and become less responsive. If the weight was on the Cog then the aircraft would roll around the weight, not lift the weight To quote the pilot who flew it 'She was such an unwieldy one' I think that sums it up.

How do you think weight distribution changes and what precise differences did it make? Did it shift CoG for example?

That is covered in the above

No doubt removing weight from aircraft will improve performance. Question is, does it worth it. In case of LMG removal from Spits, I only read it was desperate measure to intercept JU 86 P/R. Spitfire ceiling was simply not enough, so everything had to be thrown out to make it lighter. Reason it did not become commonplace is that generally climbing to 14 000 m was not giving you any practical advantage 99% of time.

No the changes to the Spits intercepting the Ju86 were more extensive than that. The LMGs were sometimes removed against the Luftwaffe a) because of the weight and b) they were pretty useless. Against the Japanese they were sometimes removed to improve agility.

Other example would be Hurricanes in Malta which tended to only have 2 x 20mm, Buffalos in Malays that sometimes had the 0.5 replaced with 0.303 and RAF P36 which sometimes had the wing 303 removed against the Ki 43.

I agree of course adding weight adds impact. I disagree that it made the aircraft useless for air combat or any measurably less competitive. It just transitioned the 109 into a heavier 190, essentially, as far as general performance goes. Less turn, less climb, more guns.

At the end of the day the pilots who flew it didn't like the impact and has been pointed out by others, if the impact was small, then why stop using them when the B17/24 bombers were such a threat?

 

[davparlr]

I believe the Russian tests were done at a relatively low level?

The is a short section on "America's Hundred Thousand" that lists some of the changes in the performance of a P-51D with the addition of 1000lbs , all internal so the only increase in drag is the induced drag due to lift. AT WEP it is supposed to have lost 3mph (5KPH) altitude not give. I believe the loss in rate of climb was 390 to 560fpm, again altitude not given and that is the important one. It is because that loss of climb rate is at ALL altitudes. loosing 450-500fpm at low level where the climb rate maybe 3500fpm isn't that big a deal (14% ?) Loosing 500fpm at 28,000ft where the climb rate is 2000fpm is a much bigger deal. (25% ?)
I don't have th ebook infront of me at the moment but the loss of service ceiling was given I believe. This in it self is not important as only the rarest of combats took place any where near an airplane's service ceiling. However this loss of climb rate affects the planes operational ceiling, the ability of a group of planes to fly in formation. In one of the Spitfire/JU 86 intercepts there were two Spitfires but one was not able to keep formation with the other. This will move down several thousand feet also. AnotherBUT few combats took place at this altitude either. A climb rate of 500pm (2.52meters/sec) doesn't really offer a lot in the ability to recover from a maneuver. It doesn't even offer much in the way of sustaining altitude in a moderate turn like 1.5-2 "G's.

A good chart for looking at the impact of weight on the performance of a P-51D was done by North American. Ceiling differences can be determined. Variations of performance impact on varying initial operating weight is also shown.

http://www.wwiiaircraftperformance.org/mustang/na-46-130-chart.jpg

 

[GregP]

I think you'd lose more than 8 kph. More like 10 - 15 mph (16 -24 kph).

Sorry, I don't take anything from Kurfurst as a source, just a starting point.

 

[davparlr]

It is the loss of climb rate that affects things more than speed.

I agree.
All the Italian WWII fighter pilots that I had the opportunity and the pleasure to interview told me exactly this.
Climb rate it's more important than sheer speed.

I am not sure of SR quote as it applies to this comment but Elmas quote certainly does. Combat does not start with a turning fight. It starts at first sight of the enemy and the decision to fight. Airspeed allows for control of the decision. The faster plane can chase down or evade the slower one. This is a major advantage in seeking a fight that favors your situation or avoiding one that doesn't. And, modern combat analysis has combined the various factors of climb, turn rate, airspeed, altitude, etc. into energy management. Let's take two aircraft, a P-51B and a Bf-109G, both flying at 25k ft, the P-51 is easily capable of doing 430 mph with some airspeed in reserve, the Bf-109 doing 400 mph. They spy each other at the same time at 10k ft range. First case, the P-51 is low on fuel, out of ammo, or some jammed guns the Bf is ready for combat. The P-51 turns away and is confident the Bf-109 will not catch him. Second case, the Bf-109 is low fuel, out of ammo, or some guns jammed, the P-51 is combat ready. The Bf-109 turns to flee, but knows he cannot outrun the Mustang and will have to try to out maneuver him, if fuel allows. In four minutes the P-51 overtakes the Bf. With equally competent pilots, there little hope for the severely crippled Bf. Now let's assume both aircraft are combat ready and both decide to engage. If they engage at these speeds, the Mustang will enjoy a 16% higher energy level based on airspeed delta alone. With similarly competent pilots with knowledge of energy management, the advantage will be with the Mustang and its pilot's ability to use its extra energy for maximum effect.

Small deltas in airspeed have little impact, however significant air speed does control the tempo of the engagement, thus the pursuit of airspeed has been a universal constant, or else WWII would have been fought with biplanes.

 

[davparlr]

So are roll and acceleration.

The Me-109 had excellent acceleration and climb. I suspect it was still superior to most other aircraft even when carrying an additional 215kg.

This is true for the very late and limited K but is a simplistic statement that is not true over various situations for other Bf models. The best Bf-109Gs could never out climb a late model Spitfire IX or XIV, nor would it out climb a post May '44, P-51B and barely eke out better climb than a P-51D. And since acceleration is excess hp to weight, not max hp to weight, at higher airspeeds the late model Bf-109Gs will not out-accelerate a P-51B or D, or Spitfire XIV since most of it hp is used to maintain airspeed.

 

[Shortround6]

I was referring to changes in handling. A change in speed alone of 8kph or even 15kph is NOT going to make a big difference in the success or failure of most intercept or air combats. Your example uses a 30mph or 48kph difference.

To try to use you example the Mustang and it's wingman are chasing a pair of 109s. one a 3 gun and one a 5 gun. as the Mustangs close both 109s bank left and start to turn. Both 109s bleed of a bit of speed. The 3 gun is supposed to be just a few (8-10kph faster) bu the 5 gun needs to generate even more lift in the turn so even at the same radius and speed his drag goes up more than the 3 gun and he starts to bleed off even more speed. Now let us say, for the sake of argument, that the 109s are not at full speed and neither are the Mustangs. What options do the 109s have? tighten the turn and slow down even more but hope to out turn the Mustangs and stay at the same altitude? Do a spiral dive for a really tight turn radius but have to drop thousands of feet per minute to maintain speed? Do a climbing turn, a broader turn but climbing while turning so the Mustangs can't get a straight away shot?
A problem our pair of 109s have is that at 25,000ft their rate of climbs are much more different than their speed which means while the climbing turn may work for the 3 gun fighter but may not work at all for the 5 gun. The difference in climb rate at sea level seems to be 4meters/sec according to some documents on the Kurfurst site. Time to 6000meters is 5 min 14 secs for the 3 gun and 6 min 18 seconds for the 5 gun. Climb at 8000 meters for the 3 gun is 10.9m/s or 2158fps while the 5gun is going to be between 6.9 and 7.9m/s ( 1366-1564fpm). In the diving turn the 5 gun fighter is going to either fall way behind the 3 gun in speed if both descend at the same rate and use the same radius turn or if it keeps the same speed will have to loose hundreds more feet of altitude per minute. if trying for a constant height turn the 3 gun will be able to pull a tighter turn.

In short my phrasing may have been bad. Between the 3 gun 109 and the 5 gun 109 "the loss of climb rate" that the 5 gun fighter suffers from in comparison is much more important than the loss in straight line speed.

Climb rates are for the 109G-1 using 1.3 Ata but do show the difference

 

[davparlr]

I was referring to changes in handling. A change in speed alone of 8kph or even 15kph is NOT going to make a big difference in the success or failure of most intercept or air combats. Your example uses a 30mph or 48kph difference.

This is what I thought you meant. I just wasn't sure. I don't disagree with any of your arguments.

 

[Elmas]

Pierre Clostermann in his book "The big show", Chapter "Radar at dawn" pag. 78, Edition 2004.

Clostermann saved his neck because "the Spitfire's superior manoeuvreability had got me out of the wood".
The German Pilot" knew that my Spitfire turned better and climbed better, and that his only hope was to outdistance me...."
But the Me 109 ended in "a ball of fire, rolling slowly towards the forest of Eu..."

About the importance of climbing speed and roll ratio it is very interesting to read.

 

[davparlr]

an example does not a good argument make.

 

[Elmas]

an example does not a good argument make.

Well.
Let's begin with Newton's Laws, General equation of motion, Moments of first and second order, conservation of linear momentum, last but not least

conservation of angular momentum and so on.
But a little bit boring from my side, I suppose......

 

[davparlr]

Well, I will see your retort with my equal retort from Wikipedia, both of which add nothing to the argument.

Vizefeldwebel Franz Hemer of Jasta 6 said, "The triplane was my favorite fighting machine because it had such wonderful flying qualities. I could let myself stunt — looping and rolling — and could avoid an enemy by diving with perfect safety. The triplane had to be given up because although it was very maneuverable, it was no longer fast enough."[14]

 

[Elmas]

Strange as it may sound to you, the ice skater and the Me 109 with the cannons under the wings have in common the same physical law about the conservation of angular momentum.
But you clearly have no idea of what the conservation of angular momentum is, so for me the conversation ends here.
Cheers

 

[Glider]

Elmas is quite right about it being an example, in fact its a very good example. The skater tucks her arms into her body and the rotation speeds up, when the arms are extended the rotation slows down. The momentum is constant.

The same rule applies to the aircraft which has weight added to the wings.
The design of the control surfaces impart a momentum to the aircraft one that stays constant at a given speed altitude etc. Keeping the weight close to the Cog as in a skater arms close to the side, in a clean Me109, pilot, engine, guns, ammo and fuel all close together, gives it its agility or if you like turn which is part of the agility.

By putting weight in the wings, like the skater who extends her arms, the rotation (skater) turn (Me109) will slow down as the momentum imparted by the control surfaces is constant.

 

[davparlr]

I am confused

Elmas first said

All the Italian WWII fighter pilots that I had the opportunity and the pleasure to interview told me exactly this.
Climb rate it's more important than sheer speed.

I said that I didn't agree and posted the rationale for my position.

Elmas then reasonably responded with a quotes he heard from a fighter pilots supporting his comment.

I posted a comment indicating that individual comments do not provide strong support for an argument.

Elmas then responded to me with a comment about general laws of motion and a picture of an ice skater. I was starting to get lost.

I responded with a pilot comment supporting my position on airspeed, showing how easy it is to get examples to support an argument

Elmas responded with this

Strange as it may sound to you, the ice skater and the Me 109 with the cannons under the wings have in common the same physical law about the conservation of angular momentum.
But you clearly have no idea of what the conservation of angular momentum is, so for me the conversation ends here.
Cheers

Now I was really confused. How did that Me (Bf?)-109 with cannons get into the argument over airspeed verses climb? I kinda think it was addressing an earlier post on this thread.

I did find out that I have no idea what conservation of angular momentum is, however.

And then there is Gilder

Elmas is quite right about it being an example, in fact its a very good example. The skater tucks her arms into her body and the rotation speeds up, when the arms are extended the rotation slows down. The momentum is constant.

Gilder, please tell me how a skater, who can rotate faster when she pulls her arms in, can contribute to the argument of climb rate being more valuable in air-to-air combat over superior speed. I really need to be straighten out.

 

[Shortround6]

We may be crossing things up. The addition of the gun pods not only affects level speed (a little), climb ( somewhat more), turning circle ( both drag and excess power at a given speed) but roll response.
I am not so sure about the conservation of momentum thing. A skater may be able to change rotational speed by moving arms in and out. a fighter cannot slide the guns along the wings
A 5 gun 109 may be able to roll the same number of degrees per second as a 3 gun 109. What it won't do is reach that peak rolling speed quite as quickly. It is going to take more time to accelerate the greater weight (mass?) out in the wings up to the same rotational speed given the same force applied (same sized ailerons, deflected to the same angle at the same airspeed.)
I would note that it is rather useless to defend the 5 gun 109 by listing other aircraft with wing guns. We are talking about the difference between a 3 gun 109 and a 5 gun 109, not the difference between a 109 and a Spitfire or a P-47. Unless someone can contribute the difference in roll response, that is roll acceleration, between various armament setups in these aircraft. Simply saying the 5 gun 109 must have been OK because the Spitfire had wing guns is no proof at all. Spitfires had different roll response depending on type of aileron and type of wing tip. some were much better than others. Planes had different peak rolling rates and different roll accelerations for a number of reasons, like wing shape (plain form) and size, aileron shape, size, placement and 'throw' in addition to mass or weight distribution along the wing. In the case of the 109 3gun vs 5 gun the only variable is the mass distribution, trying to bring another aircraft introduces way too many variables for a valid comparison to be made.