Counter-rotating propellers on the Hs 129B-2

[greybeard_52]

The model of the plane in question has currently the two engines that rotate in the same direction. This makes takeoff nearly impossible. Someone has even developed a specific technique to do it, but I think it would be better to stick to historical reality, so I invite the developers to want to give the two engines (and their propellers) opposite rotations, with what follows on the direction of the relevant torques.

[Plurp]

48 minutes ago, greybeard_52 said:

The model of the plane in question has currently the two engines that rotate in the same direction. This makes takeoff nearly impossible. Someone has even developed a specific technique to do it, but I think it would be better to stick to historical reality, so I invite the developers to want to give the two engines (and their propellers) opposite rotations, with what follows on the direction of the relevant torques.

They do counter rotate, as seen while hand propping during start.  The left engine rotates counter-clockwise (left) and the right engine rotates clockwise (right).  This can also be seen from in the cockpit and external views while they are running, especially when slowing down time.  

 

As far as takeoffs.  Using brakes at the beginning, rather than rudder seems to help a lot until there is enough speed for the rudder to be effective.

 

Edit:  I will admit in flight, the props give the appearance to be rotating inboard while the nose cones are rotating outboard.  After entering cruise by lowering prop pitch, they seem to switch (props outboard, nose cones inboard.)  They still rotate opposite of each other.

Edited March 12, 2023 by Plurp

[greybeard_52]

5 hours ago, Plurp said:

Using brakes at the beginning

THE ANIMATION is correct but not the torques developed by the two engines, which are in the same direction! The very fact that you are forced to use the brakes differentially on takeoff proves that the torques of the two engines SUM UP! Just ask yourself if you do the same on takeoff with the P-38, which has its propellers REALLY spinning in opposite directions!

[Charon]

I think it's just a matter of taildragger vs tricycle landing gear. The A-20 has two engines that both turn clockwise, but it's easy to handle because of the tricycle landing gear.

 

Now, I've long suspected that the ground-looping tendencies of tail-dragger twins are exaggerated in Il-2. It seems odd that the Bf 109 would be easier to take off in than the Ju 88, for example, and if the Ju 88 was as difficult to handle as depicted in the sim, I expect we'd read about them crashing a whole lot more. But I have no hard data to support this.

[LukeFF]

Just now, I./JG3_Charon said:

if the Ju 88 was as difficult to handle as depicted in the sim, I expect we'd read about them crashing a whole lot more. But I have no hard data to support this.

 

It's just an anecdote, but in one of the Black Cross / Red Star volumes a Ju 88 pilot described it as handling like "a diva." I.e., it wasn't the easiest plane to handle on the ground.

[FeuerFliegen]

I do wish the Bf109 was more difficult to take off and land; I've heard that 10% of Bf109s before the upgraded landing gear of G-4 and later models were lost due to crashes in take off and landing.

 

It should be so that people actually appreciate the benefit of taking a G-4 over a G-2 because of the upgraded landing gear; the way it is now, I've never heard someone seeing the G-4 and later models landing gear as a positive; it's only seen as a negative because of the added drag.

 

 

On 3/12/2023 at 7:26 PM, greybeard_52 said:

THE ANIMATION is correct but not the torques developed by the two engines, which are in the same direction! The very fact that you are forced to use the brakes differentially on takeoff proves that the torques of the two engines SUM UP! Just ask yourself if you do the same on takeoff with the P-38, which has its propellers REALLY spinning in opposite directions!

 

Maybe try turning off one engine, feathering the prop, and seeing how much the plane yaws to the opposite side.  Then try it with the other engine, and see if it yaws an equal amount to the other side.  I suspect this might tell you if they are properly modeled as counter-rotating, instead of just graphically.

[Yogiflight]

On 3/13/2023 at 12:26 AM, greybeard_52 said:

Just ask yourself if you do the same on takeoff with the P-38,

 

On 3/17/2023 at 10:11 PM, I./JG3_Charon said:

I think it's just a matter of taildragger vs tricycle landing gear.

A bit late to the party, but my 2 Cents. What Charon posted, plus one rudder in the middle vs. two rudders behind the propellers.

My way to takeoff with the Hs 129 (and the Ju 88 as well) is to throttle up slowly, so I can always react on side movements of my plane and only get the full engine power when it is already moving fast enough, that the rudder has full effect. Additionally lift the tail as soon as possible. Taking off with the Hs 129 isn't very hard as long as there isn't too much crosswind. The first mission of the Kuban career with 8m/s crosswind certainly is a challenge.