propstryker

My Feedback: (2)

Has anyone had an issue with this model nosing over on landing? Maybe mine is just too nose heavy and I need to move the CG back? Or, is this a common characteristic of this short coupled airplane?

All Day Dan

My Feedback: (5)

The proper location of the CG is determined mostly by the mean aerodynamic chord of the wing or wings as it effects the model in flight not the ground characteristics. You could try moving the landing gear forward. Leave the CG at the recommended location. Dan.

propstryker

My Feedback: (2)

Thank you All Day Dan for your ideas.

daveopam

My Feedback: (9)

Agree with Dan. But, moving the CG back a little can reduce landing speed. Not that you can float a biplane in. Most bipes however have a pretty wide CG range. I would not move it a bunch at once. Maybe 1/4" at a time. It should help the landing and in some cases, wake up the performance.

david

propstryker

My Feedback: (2)

Thanks Dave,
My CG is at the forward position and the plane flies fine but I think could benefit from moving the CG back just a little bit. My theory is that by moving the CG (weight) back a little, this will help with the nosing over issues. This should do the trick hopefully. You can't really move the landing gear on this plane because, when you assemble it, you bolt in the landing gear and then glue in a "cover." The landing gear is in a cavity so there would not be much room to move it forward, much like the landing gear on my Great Planes 27% Patty Wagstaff. The landing gear covers certainly clean up the bottom of the plane but make it really difficult to get at the landing gear. They should have been made removable in my opinion. In extreme cases I have seen guys make an "extender" of one inch of so where the axles bolt on, moving the wheels an inch forward.

daveopam

My Feedback: (9)

I think it will help a little, but not as much as the landing speed decreasing. I don't know how you fly(sport , aerobatic , scale) but moving the cg back can make a huge difference. I had an Ultimate that I could stall turn right into a flat spin and instantly recover. Lots of FUN! One word of caution for you and any other reader, Blenders with a short coupled bipe are really violent. So don't let it build up too much speed on the down line.
I would be really hesitant to move the gear myself. It would take away from the looks and bug me.

David

propstryker

My Feedback: (2)

I'm with you on the looks of the model and moving the gear. This is just a great looking airplane. I'm a sport aerobatic and scale flyer I guess with some attempts at 3D thrown in (not with this airplane). Yes, nothing livens up an airplane like carefully moving the CG back. Notice that I said carefully. I had a Sukhoi one time that I thought I had set up the CG adequately and I did not. It was really a handful once up in the air cause it was tailheavy.
Slowing down the landing would be OK too.

jetmech05

Are you sure that the gear is on in correct position. Some gear have a sweep to them. If yours are swept the sweep is forward.
if you'd like check your CG go fly get in a 45 degree up line roll inverted and let go of the sticks if you dive you're nose heavy if you climb you're tail heavy. I suspect you're going to dive pretty hard.
A nose heavy airplane doesn't want to slow down on approach nor does it want to flair on landing. Remember on approach speed is controlled by the elevator and throttle is altitude.
Seems like your touchdown speed is a bit hot. Which means not enough flair which goes back to nose heavy.
let us know how it turns out

castlebravo

This may seem wonky....but you could add a smidge of negative incidence to the top wing....just lift the trailing edge an 1/8th inch or so. This will make the lower wing stall before the top wing and raise your Angle of Attack slightly...slowing you down a little and keeping the nose up. Just a suggestion..

CB

propstryker

My Feedback: (2)

Great ideas, thanks. My guess is that you are right on the money!

propstryker

My Feedback: (2)

Good idea, thanks!

Jim Branaum

My Feedback: (3)

I apologize for not noticing and responding earlier. Between summer activities and computer problems, I have fallen way behind in a few things and forum reading is one.

I have had that bird and never had a problem with it nosing over. All the talk about CG and moving the LG is fine if you really want to craft a new aircraft, but there is probably a much simpler and easy to get to solution for you. I suspect (pretty strongly based on the evidence I collected with MY GP 1/3 scale Pitts) that your elevator throws are set way to high. Set up low rates as per shown in the book and do some high altitude slow flight looking for the stall. Once you get used to it, you can plan your approaches better and maintain flying airspeed all the way to the flare. Usually nose overs are from stalling before the mains are actually on the ground and the aircraft dropping in and when you get the slight bounce, over it goes. The Pitts lands a little faster than many birds and is squirrely on the ground due to the short coupling, but the coupling has nothing to do with nose overs but high speed on the taxi or dropping it in does.

Unless I can talk you out of that bird... I really miss mine, radio failure ate it.

jetmech05

I don't understand how checking the correct way the gear is on or checking CG is crafting a new airplane. A stall on landing would not be a nose over it would be a bounce

Jim Branaum

My Feedback: (3)

Checking CG and correct installation of the LG is very different from moving them to non-standard locations. The CG shown IN THE BUILD MANUAL is correct and works. A flight check is good and will show differences between what you want for various types of maneuvers and what you may have (I don't recall where the manual CG worked out). I thought I saw a suggestion to move the landing gear, which if it is already correctly installed is crafting a new bird. Since that bird has fiberglass struts and a metal cabane assembly, changing the incidence of the top wing is also non trivial.

*I* think your comments about not enough flair miss the mark a bit. If there is not enough elevator authority to carry the flair attitude until the aircraft stalls, the control has been set up incorrectly. That has noting to do with CG. Entirely to many folks do stall that type of bird in which does make for a bounce and nose over. Part of the problem is that many don't recognize the stall when it happens. Scale birds stall a bit differently than the trainers we teach (taught) folks to fly with. It is difficult for many to make the transition to landing faster. I suspect that is part of the problem here which makes it a little less serious.

The other thing Propstryker might consider is some very high altitude slow flight to get comfortable with the plane just before it stalls and to recognize when it is stalling. I suggest some level figure 8's starting at 1/2 throttle with the aircraft hitting the crossover point as it is coming at you. This gives you 2 things to learn, relearn, or get comfortable with as you search for the stall/control limitations at slow speed. Each circuit, reduce the throttle 2 or 3 clicks until it starts to be difficult to maintain altitude in the turns, then make the reductions 1 click each. When it falls out, power back up, reestablish your flight path, and reduce the throttle to just above that point and do some circuits. This should help you get comfortable with the aircraft and prepare you for more managed approaches that don't end up with nose overs.

JYNSHO

daveopam

My Feedback: (9)

Good thoughts Jim. I bow to your experience since I've never flown that particular plane. To clarify: my opinion about the CG was designed to slow the landing speed down. Most flyers are not as anal as I am with set up. They get the CG close and if it flys, never touch it again. Many times there are great gains in trying different CG locations. Moving the CG back a touch in many cases can result in a higher AOA on landing and a reduction in landing speed. I would also reinforce what you said about playing around with low speed flying at a higher ALT to get a good feel for it.

David

Propworn

My Feedback: (3)

I have had two of these both powered with a Brison 3.2 and have never had a problem with nosing over. My C of G was right on as recommended in the instructions. The landing gear is tapered forward and it will mount backwards so make sure the rake is to the front
.
Long grass and fast tail up or wheel landings can result in nose overs because of the extra drag on the wheels as the elevator looses its authority when the plane slows.

Most landing problems with the GP Pitts I have observed and yes it took me a few flights to figure it out myself is that power is cut to an idle far too soon on landing.
The model is not being flown in to the landing but some make the mistake of chopping the throttle too soon. Then with that big prop acting like an airbrake its worse than landing dead stick. I found the plane landed better if I kept the throttle at a fast idle and flew it to the landing. I then level the plane at five or so feet off the ground or obstructions at the end of the runway. As you pass the end of the runway the model should slow in level flight and start to settle. You may have to reduce throttle until it starts to settle but it’s not necessary to chop the throttle yet. As the plane settles foot or two above the ground ease up elevator into it just trying to hold that altitude. The tail will settle and the plane will further slow and settle. Just as the plane touches down chop the throttle.

Dennis

propstryker

My Feedback: (2)

Nice ideas guys. Yep, grass and fast tail up landings I have certainly done. I really like the figure 8 idea of checking slow flight versus slowing down and watching a wing drop.