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2019 Fantasy Aircraft Design & Build Challenge. X-Wing fighter

Chuppster

Well-known member
#22
It appears you are lacking in elevator authority. Could you try two motors, one on top of the other, with differential thrust? That way you can get it to pitch up? I bet you have plenty of roll authority it just seems that you also need something to give you a bit of a push up.
 

kilroy07

Legendary member
#23
Hummm.... I don't know enough yet to offer any other suggestions...
And frankly I am a bit worried now about my own design as it is similar overall to an X-Wing...

Are you planning on staying with a profile build or at some point fleshing her out?
Many years ago I had an old Estes rocket of the X-wing and it had short fins on the rear of the 4 engines, I wonder if adding the engines in profile would give it more surface area to help with the nose swinging around like that (once it gets to a certain point, that nose really whips around doesn't it...) :cautious:

it was had to tell in the video, do you have any control surfaces yet or was that simple powered glider tests?
I wonder if active stabilization would help?... (I have a couple hobby eagle A3s laying about...)
 

DamoRC

Elite member
Mentor
#24
Well..... Here are the first tests......

X Wing Experiments
First off, kudos to your perseverance with this and your build skills, it was fun to watch you throw it again, and again, and again....

On the flight issues, the behavior of the plane reminds me of an answer I received from @Joe M when I had issues with a design previously. I passed this advice on in another thread.

"The arrow analogy is probably the easiest way to conceptualize it. An arrow with fletching flies straight while and unfletched arrow tumbles. The fletching moves the AC of the arrow back behind the center of pressure which makes it dynamically stable. It just sort of "wants" to fly straight. "

So if you think of the X-wing as an arrow, it should be weighty in the front and light and draggy in the back. The X-wing you have is draggy in the back, but also weighty in the back. When you try to change direction, the weight in the back wants to keep going in the original direction, causing the plane to slip in the turn, then the nose catches all the air, and, well, you see what happens. It's like an arrow shot out of a bow feathers first. Any way you can move the CG to extremely nose heavy to see what she does?

DamoRC
 

Aviator08

Flagstaff,AZ
#25
Hummm.... I don't know enough yet to offer any other suggestions...
And frankly I am a bit worried now about my own design as it is similar overall to an X-Wing...

Are you planning on staying with a profile build or at some point fleshing her out?
Many years ago I had an old Estes rocket of the X-wing and it had short fins on the rear of the 4 engines, I wonder if adding the engines in profile would give it more surface area to help with the nose swinging around like that (once it gets to a certain point, that nose really whips around doesn't it...) :cautious:

it was had to tell in the video, do you have any control surfaces yet or was that simple powered glider tests?
I wonder if active stabilization would help?... (I have a couple hobby eagle A3s laying about...)
The last set of videos had a more traditional fuselage with the exception it was open down the center, ( the hope was that would give it more vertical stability..... didn't really help. )

I will probably try adding tail fin(s) to see how that goes.

Yes , it did have elevons, but they were no match for the weather vane affect. It also has stabilization , but it is not set up correctly for elevons, it probably helped in the role rate, but not in pitch.
 

Aviator08

Flagstaff,AZ
#26
First off, kudos to your perseverance with this and your build skills, it was fun to watch you throw it again, and again, and again....

On the flight issues, the behavior of the plane reminds me of an answer I received from @Joe M when I had issues with a design previously. I passed this advice on in another thread.

"The arrow analogy is probably the easiest way to conceptualize it. An arrow with fletching flies straight while and unfletched arrow tumbles. The fletching moves the AC of the arrow back behind the center of pressure which makes it dynamically stable. It just sort of "wants" to fly straight. "

So if you think of the X-wing as an arrow, it should be weighty in the front and light and draggy in the back. The X-wing you have is draggy in the back, but also weighty in the back. When you try to change direction, the weight in the back wants to keep going in the original direction, causing the plane to slip in the turn, then the nose catches all the air, and, well, you see what happens. It's like an arrow shot out of a bow feathers first. Any way you can move the CG to extremely nose heavy to see what she does?

DamoRC

Glad I could provide some humor. :D

The arrow analogy sounds interesting.... I will try with a more nose heavy configuration . Maybe even shrink the tip of the nose a little.

Also going to try lifting wings that are a bit larger and see if that counters the weather vane affect any.
 

SlingShot

Maneuvering With Purpose
#27
Hi Tim! Nice to see you back and working so hard.

I agree with Damo. If you watch the Goblin trials you will see a similar struggle with CG. I also think a tractor might be a lot easier.

Edit: BTW. My old granny bought us the original lawn darts back in the day. (She really loved us!) They were EXTREMELY nose heavy and flew great.
 

Aviator08

Flagstaff,AZ
#28
Hi Tim! Nice to see you back and working so hard.

I agree with Damo. If you watch the Goblin trials you will see a similar struggle with CG. I also think a tractor might be a lot easier.

Edit: BTW. My old granny bought us the original lawn darts back in the day. (She really loved us!) They were EXTREMELY nose heavy and flew great.
Thanks, Maybe a tractor setup is the way to accomplish the weight in the front. That would be easy enough to try. I think if it was too heavy in front the elevons would become totally ineffective though. I think I will start by slimming the nose a little and add weight up there, then if that doesn't work build a new fuselage and put the motor up front.

Thanks guys for the suggestions. :)
 

Keno

Well-known member
#29
You might look at my Thread on the X Wing Bipe it flies great and might help you in your efforts. You are welcome to its design and keep up with your work.
9/8/2018 - I have reviewed your efforts a bit more on these type of planes the CG is only about 5 - 10% back from the leading edge of the wing and requires, I believe it is called reflex/reflect upward in the wings trailing edges wing. Sorry short term memory problems here.

 
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#30
You might look at my Thread on the X Wing Bipe it flies great and might help you in your efforts. You are welcome to its design and keep up with your work.
9/8/2018 - I have reviewed your efforts a bit more on these type of planes the CG is only about 5 - 10% back from the leading edge of the wing and requires, I believe it is called reflex/reflect upward in the wings trailing edges wing. Sorry short term memory problems here.
Nice Keno. Thanks for sharing. Answers a couple of questions I had . Hopefully I can come up with something that works. :unsure:
 
#31
Alright...... Round 3. Changes made,

Made wings lifting airfoil ( Basic FT style ) and larger
Shortened Nose 1 1/2"
Closed up the front of the fuselage
Made vertical stabs out of clear plastic
Moved CG forward to front of the wing

Toying with the idea of making a clear canard , but after seeing Keno's design I think I will hold off on that.

XWing 1.PNG


XWing 2.PNG


XWing 3.PNG


XWing 4.PNG

ALL UP WEIGHT = .2 LBS

Test fight to be on the next calm wind opportunity.
 

Keno

Well-known member
#32
Alright...... Round 3. Changes made,

Made wings lifting airfoil ( Basic FT style ) and larger
Shortened Nose 1 1/2"
Closed up the front of the fuselage
Made vertical stabs out of clear plastic
Moved CG forward to front of the wing

Toying with the idea of making a clear canard , but after seeing Keno's design I think I will hold off on that.

View attachment 115007

View attachment 115008

View attachment 115009

View attachment 115010
ALL UP WEIGHT = .2 LBS

Test fight to be on the next calm wind opportunity.
On the stab you can also put some of it on the bottom. An interesting point is the stab will act as a aileron/elevon, in respect to a rudder movement its action is reversed. Put a big R2 in rear seat, the droid would love the ride. The CG will probably be back at about 10-15% from the leading edge. You will need some up elevator in you elevons the setup gauge in the FT Arrow is pretty close to what you need. Be ready for up elevon on maiden. Looks great awaiting your report on first flight. forgot something of interest a friend of mine couple both top and bottom elevons together with a rod to improve control
 
#33
On the stab you can also put some of it on the bottom. An interesting point is the stab will act as a aileron/elevon, in respect to a rudder movement its action is reversed. Put a big R2 in rear seat, the droid would love the ride. The CG will probably be back at about 10-15% from the leading edge. You will need some up elevator in you elevons the setup gauge in the FT Arrow is pretty close to what you need. Be ready for up elevon on maiden. Looks great awaiting your report on first flight. forgot something of interest a friend of mine couple both top and bottom elevons together with a rod to improve control
Thanks, I will start with that CG. I plan on adding R2, guns, engines, etc after i get it to fly well. That is of course IF I can get it to sustain flight.....
 
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Keno

Well-known member
#38
Okay.... A little more progress this morning. I'm calling it a " flight" :D



Next will be vrs 3.5 Bigger motor, bigger servos for more elevon authority.
Look great what you might think about is elevons on both top and bottom wings couple together, that is the way I am going on my new one.
 
#39
Look great what you might think about is elevons on both top and bottom wings couple together, that is the way I am going on my new one.
The last video had the elevons on both wings. It did help, but not enough. I will put a little bigger servos on 3.5
 

Keno

Well-known member
#40
The last video had the elevons on both wings. It did help, but not enough. I will put a little bigger servos on 3.5
Can you increase the size of elevons? Not sure about your servo situation It could be a problem. Mine are full length of the wings. A friend of mine who is an excellent pilot and been around this hobby for quite some years recommended that I couple them together. I also noted that when I was flying that I need to increase their size which I did and it helped but still needed more. I really like you canard I think we have two different approaches I went for simitar (Bill Evans) and you for the Long Easy. I think there may be another and that is a flying foot ball and I can see the this in the Strix. Wings on a foot ball not a bad Idea. Hey got to go, excellent job.