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Grunder Industries ADF-01 Falken build log

Mr. Gandalf

Well-known member
#81
I finally got a nice day to try and fly the falken, I didn't build a new plane and I'm glad I didn't because after a few nosedives the cockpit was totally destroyed. I took the advise of @Namactual and didn't sweat the nose damage, and the funny thing is, is that it glides just fine without it!o_O
Anyway I still need to adjust the thrust angle, I tested it by giving it a good toss and then applying throttle and it dives harder when it is given more throttle.
 

L Edge

Well-known member
#82
I finally got a nice day to try and fly the falken, I didn't build a new plane and I'm glad I didn't because after a few nosedives the cockpit was totally destroyed. I took the advise of @Namactual and didn't sweat the nose damage, and the funny thing is, is that it glides just fine without it!o_O
Anyway I still need to adjust the thrust angle, I tested it by giving it a good toss and then applying throttle and it dives harder when it is given more throttle.
Try about 5 degrees and see what happens.
 

Mr. Gandalf

Well-known member
#85
Sorry it has taken me so long to reply, but I wanted to have more to show than just the damage, but here are some pictures of it anyway.

1558659783407.png 1558659864656.png 1558659979991.png

As you can see from the first two pictures the cockpit was completely kiboshed, but worse was the wing bending as can be seen in the last picture. I am pretty sure that this was partly to blame for the violent down pitching that this plane suffered from. However, I think that the main cause was that the motor was directly above the center of gravity, so I decided to make some modifications and build a whole new airframe.
 

Mr. Gandalf

Well-known member
#86
Here is my progress on the new build.

1558660738816.png

This picture is just a mock up so I still need to mount the cockpit to the wing. I moved the power pod down so that the motor's thrust line would be in the center of the wing which should take care of the downward pitching moment, but that threw off the geometry of the old cockpit mount, so that will have to be redesigned. I reinforced the leading edge of the center wing panel with some bamboo skewers so that it won't sag like the last one, and I put the servo wires inside the wing so it looks a lot cleaner. I am vey happy with the way this plane looks, and if it flies well then I will start working on making PDF plans.

Also @L Edge I will definitely have video of the maiden flight!
 

L Edge

Well-known member
#88
If it doesn't fly, I have 2 suggestions for you.

1) When I built mine, I ended up with small elevrons and it's deflections. Try less deflection and have a high expo rate.
2) You have a small area of wing. Can you extend the leading edge by about 1 1/2 to 2" to increase the total wing area and that changes your CG.. Might help you.

This is based on 3 FSW planes I built. Here is one of them.
https://forum.flitetest.com/index.php?threads/forward-swept-wing-using-64mm-edf.57659/
 

L Edge

Well-known member
#90
Thanks guys!

@ L Edge what were your rates and expo for that X-29? Right now I have 12 degrees and 30 percent expo on both channels.
Finally, got back to internet. My elevon is only 1 1/2" wide and I have only 3/8" max (25 degrees) deflection and my expo is 35 percent for elevator and 30 for aileron. What my concern was your control surface takes up quite a bit of wing surface and with a large deflection of your wing makes it like a 3D airplane, very twitchy. I use very little deflection to make it go.
 

Mr. Gandalf

Well-known member
#91
It has been a long time since I posted any progress because I have been working on setting up a youtube channel, working on other projects, and pondering this planes quirks. I finally have video to help those watching this thread help me, and by the way thank you all for your tips, advice, and encouragement!

Before the videos however, I need to list some changes made to the plane, first I have added a bunch of tail weight to move the CG back, I also removed the landing gear, and I cut off the engine nacelles and replaced them with profiles.




I will upload pictures of the current airframe after I build a new one because this one is pretty banged up.

Before I cut the engines off this thing it would just tumble around on all three axes, but now the "turn" in the videos was just yawing that I think was caused by the engine profiles not being parallel to the thrust line. So the main problem is this model's inability to turn like most other planes, and I have no idea what is causing it! :unsure:
 

L Edge

Well-known member
#92
Before you take the motor off, try moving the CG for it is flying tail heavy. Secondly, put more expo in the controls or reduce the throws which I had to do. If the controls are extended to high, it will cause a yaw problem.

Here is a video where I had to add weight to nose to move the CG forward with very little extension of my controls.

 

Mr. Gandalf

Well-known member
#93
After I crashed the last iteration of this plane I have rethought the design. In an attempt to make a scale representation of the falken I ended up with a model that didn't fly, was structurally weak, and was hard to work with (in both the build and setting it up before flights), so I have simplified the build in every area to increase functionality while trying to keep good aesthetics. I eliminated the airfoil in favor of a single layer of foam for the wing, changed the three dimensional engine nacelles to profiles, and designed a new cockpit built using traditional flite test techniques which has allowed for a removeable nose that is very convenient to use.

1569620204573.png 1569620298055.png

As for this model's apparent inability to turn, my current theory is that the elevons, which spanned the whole trailing edge of the wing, killed lift when they were used as elevators due to their close proximity to the CG. So I'm thinking that limiting the elevons to the area aft of the ruler in the next picture will solve the problem.

1569620377696.png

I will post more build pictures as It progresses.
 

Wildthing

Well-known member
#94
After I crashed the last iteration of this plane I have rethought the design. In an attempt to make a scale representation of the falken I ended up with a model that didn't fly, was structurally weak, and was hard to work with (in both the build and setting it up before flights), so I have simplified the build in every area to increase functionality while trying to keep good aesthetics. I eliminated the airfoil in favor of a single layer of foam for the wing, changed the three dimensional engine nacelles to profiles, and designed a new cockpit built using traditional flite test techniques which has allowed for a removeable nose that is very convenient to use.

View attachment 143737 View attachment 143738

As for this model's apparent inability to turn, my current theory is that the elevons, which spanned the whole trailing edge of the wing, killed lift when they were used as elevators due to their close proximity to the CG. So I'm thinking that limiting the elevons to the area aft of the ruler in the next picture will solve the problem.

View attachment 143739

I will post more build pictures as It progresses.
Up in the air that will still look great.
 

Mr. Gandalf

Well-known member
#96
I got a chance to fly the falken, but it didn't go very well.:(




There are two or three more videos of this, but youtube isn't working for me right now so I will upload them later.

Anyway after a few more unsuccessful flights I realized that the high mounting point for the planes battery was probably making it unstable. So I taped the battery to the side of the fuse and below the CG, It did fly a little better after that, but its lateral balance was off so it kept banking to the left. Next time I fly it I will put the battery in the "laser pod" under the cockpit and hopefully it will give the plane some pendulum stability.
 

Wildthing

Well-known member
#97
I got a chance to fly the falken, but it didn't go very well.:(




There are two or three more videos of this, but youtube isn't working for me right now so I will upload them later.

Anyway after a few more unsuccessful flights I realized that the high mounting point for the planes battery was probably making it unstable. So I taped the battery to the side of the fuse and below the CG, It did fly a little better after that, but its lateral balance was off so it kept banking to the left. Next time I fly it I will put the battery in the "laser pod" under the cockpit and hopefully it will give the plane some pendulum stability.
Looks tail heavy to me.
 

Wildthing

Well-known member
#99
If you have a spot where there is tall grass try glide testing it again with battery and everything in it but don't use the throttle. If it glides good that way then maybe adjust your motor angle, shim the top so it is pointing down slightly.