Helicopter blades not working as propeller blades?

[martorad]

I'm creating a V-22 Osprey replica with the new robotic parts (incredibly original idea, I know). I am using the largest helicopter blades and the R7000 turboshaft engine. The vehicle lifts off fine, albeit with some help from vernor engines, but the second I enter it into "plane" mode the engines are massively too weak to propel it, capping at about 35m/s. The vehicle weighs 66,5 tonnes. Is there any way of improving the thrust/weight ratio without adding more rotor/jet engines? Why is it that they have enough power to lift the whole thing off the ground, but not to propel it?

Since I'm new here and couldn't figure out how to insert images into my post, here's an imgur link: https://imgur.com/a/msRQ73z

[AHHans]

Well, if it can lift, then it has a TWR greater than 1 when standing still.

But once you start moving the angle of attack on the blades changes and they produce less thrust if the blade pitch is not adjusted. I.e. did you adjust (increase) the blade pitch in horizontal flight?

[martorad]

2 hours ago, AHHans said:

Well, if it can lift, then it has a TWR greater than 1 when standing still.

But once you start moving the angle of attack on the blades changes and they produce less thrust if the blade pitch is not adjusted. I.e. did you adjust (increase) the blade pitch in horizontal flight?

Is there a way to bind a hotkey to the increase of the angle of attack in flight? I haven't been able to find out how to do it. But even if I did, I still don't think it would work. In the screenshots I have the angle set to 80. I tried setting it to 150 manually, in the SPH and while the Osprey lifts off slower, it's horizontal speed is increased - to about 65m/s. This unfortunately still isn't enough however.

[AHHans]

2 hours ago, martorad said:

Is there a way to bind a hotkey to the increase of the angle of attack in flight? I haven't been able to find out how to do it. But even if I did, I still don't think it would work. In the screenshots I have the angle set to 80. I tried setting it to 150 manually, in the SPH and while the Osprey lifts off slower, it's horizontal speed is increased - to about 65m/s.

(The angle of attack is the angle between the blade and the incoming airflow, because the direction of the airflow onto the blade changes with airspeed you cannot directly set it. What you do set is the pitch of the blade.) I believe you set the pitch of the blades by setting them to deflect and then adjusting the "authority limit" in the PAW, correct? You can bind this authority limit to one of the axis groups in the SPH and use that to adjust it during flight.

What you describe is exactly the effect I'm talking about. If you increase the pitch of the blades above the value for optimum thrust at standstill, then it will give less thrust at low airspeeds (your plane lifts slower) but will give better thrust at high airspeeds.

But: I made a test, switching the 2m prop blades with the 2m helicopter blades on one of my planes. And got essentially the same result you got: good acceleration at low airspeeds, but lousy maximum airspeed (for me it was ca. 40 m/s instead of 120 m/s with the prop blades). So I guess that this is the fundamental difference between these two types of blades: the helicopter blades give higher thrust in general but max out at low speed, and the prop blades have less thrust at low airspeeds but can keep their thrust up to higher speeds.

You could try prop blades instead of the helicopter blades, or adding prop blades to the same engines that you have the helicopter blades on (i.e. have two sets of blades on the same engine). But my guess is that both won't work too well. (Prop only will probably have too low static thrust to lift the plane, and with both on the same axis the helicopter blades probably generate lots of drag at high airspeeds.)

[KerikBalm]

Forward velocity requires some pretty steep pitch.

For this reason I place my helo blades, deploy them to -150 in the editor, then rotate them so that they are flat/parallel with the ground (when the nacelles point up).

Then I have from -150 to +150 to adjust the pitch, to give a much higher top speed. It requires a fairly gradual adjustment of nacelle tilt and blade pitch to achieve forward flight, but it does it quite well.

[martorad]

4 hours ago, KerikBalm said:

Forward velocity requires some pretty steep pitch.

For this reason I place my helo blades, deploy them to -150 in the editor, then rotate them so that they are flat/parallel with the ground (when the nacelles point up).

Then I have from -150 to +150 to adjust the pitch, to give a much higher top speed. It requires a fairly gradual adjustment of nacelle tilt and blade pitch to achieve forward flight, but it does it quite well.

Do you think you can make a slightly more detailed guide? If you could include a list of steps to take that would be phenomenal!