F4U hydraulics
Sun Aug 14, 2011 7:14 pm
Here is a picture of -U4 with engine under power.
The question is:
Is it a normal situation for the wings hydraulics to have one wing in flight position and the other only starting to move or is there other explenation for this photograph?
The question is:
Is it a normal situation for the wings hydraulics to have one wing in flight position and the other only starting to move or is there other explenation for this photograph?
Re: F4U hydraulics
Sun Aug 14, 2011 7:41 pm
greatgonzo wrote:Here is a picture of -U4 with engine under power.
The question is:
Is it a normal situation for the wings hydraulics to have one wing in flight position and the other only starting to move or is there other explenation for this photograph?
I know that you can pump up each wing independently by hand, as I have witnessed it being done. Maybe that's what has happened here.
Cheers,
Richard
Re: F4U hydraulics
Sun Aug 14, 2011 8:06 pm
Uhhh, no. The simple explanation is that the hydraulic pump output is too low to pressurize both wing retract cylinders at the same time, so only one will raise at a time. The wing lock cylinders are small so that both wings will unlock at the same time, but it takes a lot more fluid volume to raise the wings than the pump can supply.
The next time that you see a Corsair take off, pay attention to the landing gear retraction.
One wheel always retracts before another. The doors won't close before the wheels are up and locked.
The wing flaps have restrictors in the lines so that they are syncronized to work together.
The next time that you see a Corsair take off, pay attention to the landing gear retraction.
One wheel always retracts before another. The doors won't close before the wheels are up and locked.
The wing flaps have restrictors in the lines so that they are syncronized to work together.
Re: F4U hydraulics
Sun Aug 14, 2011 8:32 pm
yes, this is very common to see that. Also, this happens when the wings are folded down too. It's actually a rod that pushes the outer wing panel up by using the Hydraulic wing folding system. Located in the center section of the wing group,( push rod,) it will push the outer panel till the rod is fully extended. So i'm guessing that it's whatever wing has more hydraulic pressure in the lines to make one go up first before the other.
Re: F4U hydraulics
Sun Aug 14, 2011 9:37 pm
Wing fold system has a restrictors to slow the wing on the extend cycle so they don't slam down. There isn't anything that I remember on the up side.
Friction is really the factor that will affect how the fold in relation to being in sync. There really isn't any reason that they have to be in sync compared to the wing flaps that really need to be working together.
It is possible that in taxing he only needed one wing up to clear an obstacle.
We did this on the AD that crashed early this summer when it was owned by Dick Bertea. The wingspan was slightly to large either for the door or with other A/C in the hangar. I don't recall but we would hang on one wingtip, fold the wings and only one would go up. Get it to a certain angle, too high it hits the top, to far out it hits the door frame. Park the wing fold so the wing will stay in place. Push it through and extend the wings again. Repeat the process to pull it out of the hangar.
There isn't anything to select one wing to fold at a time IIRC.
The wing flaps have restrictors on the up side so they won't retract to quickly. I don't recall anything as a restrictor on the extend side. On the ground they don't have an air load on them as in flight. On the ground they may not move is sync while in flight they will. There is 2 separate hyd actuators, one in each wing to move each side. They aren't interconnected side to side. They also have a mechanism where if you put to much load on the flaps by having them too far extended for your airspeed they will retract a bit automatically until the load is reduced. This is on the R/H side.
Other factor on the ground is the engine running the pump is usually at idle so the output of the pump is reduced. Other ground use is by an electrical motor driving an aux hyd pump in some models otherwise its the hand pump. A great way to build arm muscles.
Friction is really the factor that will affect how the fold in relation to being in sync. There really isn't any reason that they have to be in sync compared to the wing flaps that really need to be working together.
It is possible that in taxing he only needed one wing up to clear an obstacle.
We did this on the AD that crashed early this summer when it was owned by Dick Bertea. The wingspan was slightly to large either for the door or with other A/C in the hangar. I don't recall but we would hang on one wingtip, fold the wings and only one would go up. Get it to a certain angle, too high it hits the top, to far out it hits the door frame. Park the wing fold so the wing will stay in place. Push it through and extend the wings again. Repeat the process to pull it out of the hangar.
There isn't anything to select one wing to fold at a time IIRC.
The wing flaps have restrictors on the up side so they won't retract to quickly. I don't recall anything as a restrictor on the extend side. On the ground they don't have an air load on them as in flight. On the ground they may not move is sync while in flight they will. There is 2 separate hyd actuators, one in each wing to move each side. They aren't interconnected side to side. They also have a mechanism where if you put to much load on the flaps by having them too far extended for your airspeed they will retract a bit automatically until the load is reduced. This is on the R/H side.
Other factor on the ground is the engine running the pump is usually at idle so the output of the pump is reduced. Other ground use is by an electrical motor driving an aux hyd pump in some models otherwise its the hand pump. A great way to build arm muscles.
Re: F4U hydraulics
Mon Aug 15, 2011 8:01 am
The delay in time in actuating hydraulically operated aircraft mechanisms is a clear thing. But even in the furthest receiver there will be some pressure and it will start to move almost at once only slower like it is with the undercarriage or , why to look far, with Corsair wings:
http://www.youtube.com/watch?v=LUnEmi7eBMs
http://www.youtube.com/watch?v=lKjbVeVUqP4&feature=related
That's why 51fixer needed the sitting team on the wing to stop it from rising, isn't it?
What bothers me in the picture is the full up position of risen wing with other fully down. Taxiing trouble is the answer best looking to me.
Thank You for very interesting technical details.
http://www.youtube.com/watch?v=LUnEmi7eBMs
http://www.youtube.com/watch?v=lKjbVeVUqP4&feature=related
That's why 51fixer needed the sitting team on the wing to stop it from rising, isn't it?
What bothers me in the picture is the full up position of risen wing with other fully down. Taxiing trouble is the answer best looking to me.
Thank You for very interesting technical details.
Re: F4U hydraulics
Mon Aug 15, 2011 11:14 am
skymstr02 wrote:Uhhh, no. The simple explanation is that the hydraulic pump output is too low to pressurize both wing retract cylinders at the same time, so only one will raise at a time. The wing lock cylinders are small so that both wings will unlock at the same time, but it takes a lot more fluid volume to raise the wings than the pump can supply.
The next time that you see a Corsair take off, pay attention to the landing gear retraction.
One wheel always retracts before another. The doors won't close before the wheels are up and locked.
The wing flaps have restrictors in the lines so that they are syncronized to work together.
I wasn't meaning that there is a switch to pump each wing independently, just that when you hand pump the wings they can go up one at a time. However, when the more powerful electrically operated hydraulic pump is doing the work there is still a lag between wings, but they do rise at the same time... one being slightly ahead of the other. It's the same thing with the undercarriage (as in one lags behind the other, but they do rise at the same time).
Richard