Scale Curtiss XP-55 Ascender
- Thread starter Larry B
- Start date
Larry B
70cc twin V2
Well it flies, it was the single most terrifying 4 minutes of my 47 year rc flying history! I ended up tearing the main gear out of the wing but it was only the 1/4" plywood mount plates that let go, and of course a bit of sheeting around the gear mount.
My wife was suppose to film the event but she blew that so I have zero pictures of the thing, sorry.
What happened was the load on the canard was way more than what I figured it was going to be, every time I banked the plane to turn of course the G's of the turn increase the flight loads on all the surfaces. When I would bank the plane the nose would start to dip down just as you would expect, but the kicker was when I went to put in some up elevator I ended up using full up with full up trim and the nose would ever so slowly come back up. The only way I was finally able to fly an approach was by flying a huge circle with a very shallow bank angle. I almost plowed the crops several times trying to fly a normal race-track pattern.
After 4 minutes in the air I finally got an approach that I thought would work, then I ran out of elevator on landing and smacked it on the grass. It will live to fly another day and this time I'll get a good camera person!
The problem is that the entire servo mount is flexing when the servo tries to move the canard. I am able to duplicate the issue by holding full up on the TX, then taking my hands and applying force to the canard like in flight. I can make the trailing edge of the canard go up almost an inch and watch the entire plywood bulkheads and servo mount flex! The servo was moving, it was just not moving the canard but instead flexing the internal mount! Just bad engineering on my part. The good news is that I can go in and stiffen the whole thing up really easy and then we'll give it another go.
My wife was suppose to film the event but she blew that so I have zero pictures of the thing, sorry.
What happened was the load on the canard was way more than what I figured it was going to be, every time I banked the plane to turn of course the G's of the turn increase the flight loads on all the surfaces. When I would bank the plane the nose would start to dip down just as you would expect, but the kicker was when I went to put in some up elevator I ended up using full up with full up trim and the nose would ever so slowly come back up. The only way I was finally able to fly an approach was by flying a huge circle with a very shallow bank angle. I almost plowed the crops several times trying to fly a normal race-track pattern.
After 4 minutes in the air I finally got an approach that I thought would work, then I ran out of elevator on landing and smacked it on the grass. It will live to fly another day and this time I'll get a good camera person!
The problem is that the entire servo mount is flexing when the servo tries to move the canard. I am able to duplicate the issue by holding full up on the TX, then taking my hands and applying force to the canard like in flight. I can make the trailing edge of the canard go up almost an inch and watch the entire plywood bulkheads and servo mount flex! The servo was moving, it was just not moving the canard but instead flexing the internal mount! Just bad engineering on my part. The good news is that I can go in and stiffen the whole thing up really easy and then we'll give it another go.
Last edited:
Jetpainter
640cc Uber Pimp
Congrats on getting it back in basically one piece. It sounds like it was a handful. Hopefully you'll get it back in the air soon.
Larry B
70cc twin V2
Thank you guys, after getting it home and checking it over the repairs are going to be easy.
Earle, I think you may have a good point. The CG was in the most forward location that I came up with. I think for the next flight I will move the CG back just a bit. With a canard if the CG is to far forward the canard will be unable to carry the load and like you say that have been a factor to the "nose dive" that I was getting.
I think it will take a couple of weeks for the repair then I'll give it another go! Next time I'll get a reliable camera operator.
Earle, I think you may have a good point. The CG was in the most forward location that I came up with. I think for the next flight I will move the CG back just a bit. With a canard if the CG is to far forward the canard will be unable to carry the load and like you say that have been a factor to the "nose dive" that I was getting.
I think it will take a couple of weeks for the repair then I'll give it another go! Next time I'll get a reliable camera operator.
Larry B
70cc twin V2
Well the second flight is in the log book, once again the gear took a beating but not to bad. This flight was done with the CG moved 1" aft of the first flight and it still seems nose heavy but at least it didn't try to plow the fields in the turns! I'll move the CG back another 1" and give it another go. I think part of the problem was that I pulled the throttle all the way back and being an electric it has no idle so the prop acts like a giant air brake. Next time I'll be sure and carry some power down final, I'm to used to a gas engine that has an idle when the throttle is pulled all the way back. Pilot error once again!