I think this is probably sufficiently different to merit its own post.

I've been simming for many years, and have taken the big plunge with controllers, etc.

I'm currently using the Alpha and Bravo yoke and throttle quadrants, and have struck a problem that I can't resolve, and am hoping that someone else has seen this and knows the solution.

I've tried taking off with several planes including the good old Cessna 152, and have even resorted to starting off from the actual runway.

What happens. Well I turn on the Master Alt & Battery switches,, and the bus 1 and 2 Avionics switched. Advance the throttle about a quarter, and use the mag/ start key to start the engine. OK so far. I release the brake, and it confirms that the brake is actually off, and gradually increase engine revs until they are showing 100% - a bit over 5000 revs.

No brakes on, engine running fine, weights OK, but the plane dawdles along the runway at 2 MPH. It'll do that down the complete main runway of Melbourne/Tullamarine until it reaches the end.

If I turn on AI piloting, it takes off just fine, and flies just fine when I take control back off the AI.

I've made sure that there are no brakes bindings on either of the controllers, not on the old Logitech rudder pedals that I'm using.

Does anyone know what might be causing this?

Please!

I've experienced a similar problem, but not exactly like yours.  I find that if I rotate before the prescribed rotate speed, the plane will not accelerate and leads to a stall and crash.

A similar thing happens coming in for a landing. If I reach stall speed, then try to accelerate, it will not let me accelerate, and then crashes. Also had it on touch and goes.  Once landed it will not let me accelerate to take off again. 

Roy

 

Do you have rudder pedals?  It almost sounds like the the brakes axis is reversed.  If you have them, try takeoff with full brake on the pedals, it might release the brakes and then you will know they need to be reversed.

24 minutes ago, MarkW said:

Do you have rudder pedals?  It almost sounds like the the brakes axis is reversed.  If you have them, try takeoff with full brake on the pedals, it might release the brakes and then you will know they need to be reversed.

Just discovered my brake pedal settings did not have the reverse settings. I have Right Brake and Left Brake set.  Changed them to Right Brake Axis and Left Brake Axis and now working fine.

Thanks Mark

+13 Points awarded to @MarkW 

Great, glad this worked.  You have probably guessed I have had the same problem.  

20 hours ago, John Glossop said:

What happens. Well I turn on the Master Alt & Battery switches,, and the bus 1 and 2 Avionics switched. Advance the throttle about a quarter, and use the mag/ start key to start the engine. OK so far. I release the brake, and it confirms that the brake is actually off, and gradually increase engine revs until they are showing 100% - a bit over 5000 revs.

5000 RPM, I hope it's not the 152 engine. Glad you sorted out the brake problem.  There is a flight control app where you can see all the surface settings including the brakes. Can't remember the name though. I use it all the time for my flight control checks. 

I've turned the Brake axis right down, by calibrating 70% of the movement to the "Off" position, so I only have brakes for the last 30%. However, this looks like the best lead so far, so I'm off to try it out right now.

OK, I tried reversing the rudder brakes, and in desperation actually deleted the bindings, so now all the rudder is - is a rudder!

I overestimated the revs (thanks, trainnut - oh, and have you voted for "I like trains" - or similar, over on flightsimulator.com?)

I have an image of my 0 knots take off roll at 100% acceleration, but I don't have a URL to load it to, so that I can post it here - sorry.

addendum: I think I'll go over to flightsimulator.com with this problem - my objective is to upload the image to somewhere that I can point to from here, if that's possible.

 

Edited May 14, 20224 yr by John Glossop
added rethought action re image

It feels like an incredibly difficult way to show potential helpers images from the sim, but I've uploaded my screeny to here: https://forums.flightsimulator.com/t/plane-wont-accelerate-beyond-2-knots-on-take-off/517640

for anyone who might be able to help me.