Fms 1400mm Corsair taxi trouble

[Tmz87101]

maidened the fms 1400mm Corsair today it flew good and landed good. Running 4000mah pack checked cg several times when trying to taxi and take off it keeps wanting to tip over a lot. And tips on trying to fix this?

New to to the forum
thank you

[themudduck]

Hey, welcome to the squawk! I don't have a Corsair but I'll bet others who do will chime in and tell you what they've done. I have lots of experience in general - and I have a ParkZone P47 that likes to tip over.

Here are some rambling thoughts I can offer (typing is free, LOL):
Your plane may be a bit nose-heavy.
In that condition it will fly really well - nose-heavy warbirds are fast and stable, but you'll have these other effects that go along with that.

You can test it in the air: first, trim your model for "hands-off" level flight at cruising speed. Then (at a safe height) fly it inverted. If you need a lot of "down" to hold it level, then its nose heavy. How much down is a variable depending on the wing design and also your preference. A pattern ship or 3D plane (symmetrical wing) will be balanced completely neutral, so it won't need more than the slightest touch of down to hold level. Warbirds are often a bit nose heavy, which is normal, and so "some" down is needed... and that is completely fine. But, if you need a lot of down to hold it level when its inverted then that's a sure sign that it's too nose heavy. If that is what happens with your Corsair, try moving the battery back a quarter-inch and test it again.

Keep in mind that manufacturers often specify a slightly nose-heavy balance point in the manual, because it makes the plane more stable and "user friendly". Consider it a starting point for flight testing to your own preference.

Nose-heavy ships need more "up" elevator in general. If you do move the balance point back, you won't need as much "up" so you should lower the amount of control throw a bit. (If you don't, it will be too sensitive.)

However, I'll tell you that I did these things with my P47 and it STILL likes to tip over!! Mainly on grass runways. It has retracts so I can't move the wheels forward. For me the solution was to increase the elevator throw but use more expo - that way I could hold full elevator to "plant" the tail down when taxiing or while landing (at slow speed) but the expo helps smooth things out while flying at higher speed. I find expo to be really helpful, I like to fly smoothly.

One last thing check your wheels to make sure that they aren't too tight. If the wheels don't spin freely that could also contribute to the plane wanting to nose over. hope that helps! Marc

[TiredIronGRB]

maidened the fms 1400mm Corsair today it flew good and landed good. Running 4000mah pack checked cg several times when trying to taxi and take off it keeps wanting to tip over a lot. And tips on trying to fix this?

New to to the forum
thank you

Welcome to Hobby Squawk!
I usually CG my tail draggers to the rear of the specified range (and sometimes further) and when taxiing use full up elevator to keep the tail planted. On landing after you've bled off enough speed that it won't jump back in the air give it elevator to plant the tail.

[OV10]

And a lot of times on the FMS birds the aft portion of the etract needed to be shimmed to kick the wheels forward. My Corsair has about 2mm of washer shims added.

[themudduck]

And a lot of times on the FMS birds the aft portion of the etract needed to be shimmed to kick the wheels forward. My Corsair has about 2mm of washer shims added.

There you go - I knew that a Corsair jockey would have the answer. I wanted to do that on my P47 but I couldn't because the wheel wouldn't fit into the wheel well like that. But every plane is different.

[boomer108]

I fly mine with 4s 3300 30c batteries and have no trouble taxing but I do keep full up elevator when taxing and a little on takeoff roll until I get up some speed.

[Grossman56]

I recall Ryan doing a video on the FMS Zero to rake the gear forward to help with that problem too.

Is this specific jus to the 1400mm or does the 1700mm have this trouble too??

Grossman56

[wrongroad2]

G'day gang,
Watch a few episodes of BAA BAA BLACK SHEEP and you will see how much up elevator is used on the full size to keep the tail down.
I have nosed my F4U [V3] a couple of times while taxiing and it has always been my fault for not using elevator or finding a divot in the grass. As our club runway has become smoother and smoother, the nose overs have almost vanished. I can not remember the last time I had one.
Oh, And do not give it a lot of throttle to move, if the wheels bind or get stuck for a moment, new props are on order.;)
Regards and respect
Daryl

[bradl4648]

yea this is typical on most warbirds and tail draggers full up on taxi and on take off with some right rudder for a few feet. 1700 is the same as well just do not use much flap if any on take off that does flip it on its nose.

[Saltydawg]

I have an old Airfield Corsair that is just ever so slightly bigger by a whopping 50mm (1450mm total). One thing to remember is with that long nose and depending on how you throttle up and just taxi, the prop torque will/can cause your plane to have a tendency to want to ground loop. Just like when you take off just a little early and your plane wants to roll left. It's a combination of tip stall and prop torque.

I just go full elevator up when taxiing and correct travel with rudder. When making my run for takeoff, I do a steady smooth throttle up with some rudder correction to counter the prop torque and depending on the windage about 20° flaps.