Plane won't accelerate beyond 2 knots on take off

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 2000 revs.

No brakes on, engine running fine, weights OK, but the plane dawdles along the runway at 0 - 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?


Sounds like you have the parking brake on TBH. On the bravo one of the buttons is bound to it by default if I remember correctly. Can you show a screenshot of the cockpit (hide the yoke) when it’s trying to accelerate but isn’t?

If not the parking brake ensure your prop pitch is correct

The brakes were unlinked from 47/48. Here is the image requested above:

Brakes off, engine revving hard, and throttle full on. I am unaware of any Cessna 152 with a variable pitch propeller, sorry, can someone please elucidate?

Have you unplugged the Alpha & Bravo and attempted a keyboard & mouse only take-off?

It’s awkward, yes, but doing so will help to isolate the issue. If you’re able to take off, then there must be some binding with the peripherals that are applying the brakes to some degree.

Start there. If that is successful, I’d plug the Alpha & Bravo back in and create a new blank control mapping for each of them. Then try taking off again — using the keyboard, of course since you won’t have maps for the peripherals.

Again, if successful, you’ll now know that the default bindings for the peripherals are causing the issue. Try to add manually start adding mappings back to them and see if the issue comes back or is resolved.

You don’t have another controller, like an XBOX controller, plugged in do you, as that could be sending conflicting commands to the aircraft?

Yeah the parking brake lever does seem to be in, although a bit hard to see. So that’s probably not it. I would go to the control settings and filter to brake, see what is bound to it. Something has to send brake commands.

I’ve already unbound everything that might have an impact on the brakes. No change, I’m afraid.

As part of my investigation, before asking here, I went into the first lesson and made sure that all the flight controls were working just fine.

Just the Del button on the keyboard. I’ve unlinked all other brake controls.

Good thought. It’s getting late (at night) here, so I’ll try this one in the morning.

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No, Alpha, Bravo & rudders, with no brake links from any of them.

Had a similar issue with the savage carbon on the runway and moving one of the rudders with the mouse “unlocked it”.

Why haven’t you launched in the air to see if it lands or tips over?

Another good question that I’ll address tomorrow (late night here). Thank you.

brake axis inverted? your pedals look like they were tapped.

Stupid suggestion (but it happened to me)

You don’t have active pause on do you ?
(it makes all the right noises but nothin happens)

Something I’ve had to do is release the brake, then reset the brake and release it again.

Even though it LOOKED released, it wasn’t.

Right at this moment, I’m contemplating an entirely different problem raising its head. I am beginning to suspect that the USB hubs that I’m using are causing problems elsewhere, and my next task is the rip out the cheap “J.Burrows” 7 port hubs and replace them with a combination of tp-link 720’s and a similar Targus offering. I’m currently coping with a wife who has Covid, so the time that I can give to simming is pretty restricted, and it will probably be a couple of days before i can report back again. Thank you for all your responses, and I shall return!

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I think you are on the right track. A lot of issues on this forum are hardware related.

This sounds like the key bindings gone wrong, however faulty controls/hardware can cause this. The most important think to remember, it is best not to use USB hubs if possible because windows 10 might keep remapping USB hardware. Sometime some USB ports go to sleep because windows power saving kicks in.