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3 Meter Fokker Eindecker fighter

Robbie

Senior Member
#1
Hey Guys,

Me and some mates are building a 3 meter Fokker Eindecker fighter foamy out of wooden dowl and depron.

We are using these plans, However have heavily modified them for the dowl frame
Foam Eindecker Top (2).pdf
http://www.rcgroups.com/forums/showatt.php?attachmentid=6949129&d=1405956091
Foam Eindecker Landing Gear (1).pdf
http://www.rcgroups.com/forums/showatt.php?attachmentid=6949128&d=1405956091
Foam Eindecker Fuse Side (2).pdf
http://www.rcgroups.com/forums/showatt.php?attachmentid=6949127&d=1405956091
Foam Eindecker Formers (1).pdf
http://www.rcgroups.com/forums/showatt.php?attachmentid=6949126&d=1405956091

Componants:
Motor: Turnigy Aerodrive SK3 - 4250-500kv
ESC: Hobby King 60A ESC 4A UBEC
Servo: Corona DS339HV Digital Metal Gear Servo 5.1kg/ 32g/ 0.13 Sec
Battery: Multistar High Capacity 4S 5200mAh

We are building a Wooden Frame which will then be covered in depron and reinforced with carbon spares

Now the frame is finished we are planning to cover it with Depron and then attach the wings.
Eindecker 6 (low Qualtiy).jpg
Eindecker frame 7 (low Quality).jpg
Eindecker 9 low quality.jpg
If any of you have any advice or tips it would be much appreciated and I will update this post as the build continues.

Thanks,
Robbie
 

Attachments

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AkimboGlueGuns

Biplane Guy
Mentor
#2
Cool project. I'd actually recommend DTF for covering the plane since it's cheaper and the covering is not really adding that much to the structure. Depron will work just fine, but if you want to save some cash, I'd imagine DTF will work just fine.
 

Robbie

Senior Member
#3
Cool project. I'd actually recommend DTF for covering the plane since it's cheaper and the covering is not really adding that much to the structure. Depron will work just fine, but if you want to save some cash, I'd imagine DTF will work just fine.
Thanks Man if i was doing this from scratch I would but I already have about 10 sheets of depron and I need it done within a week for a fair. But thanks for the advice, this is the first time I have built a plane using a wooden frame, if it works well and I do it again in the future I will defefinatly consider DTS.

Below is a picture of the Frame being built

Eindecker Frame low quality.jpg
 
#4
Dollar Tree Foamboard is very hard to acquire cheaply in the UK.

Unfortunately I have no pictures but the tail has been attached.

Wings are currently being built, covering the sides with depron is the last thing we will do.
 
#6
IMAG0369.jpg IMAG0370.jpg IMAG0371.jpg IMAG0372.jpg IMAG0373.jpg IMAG0374.jpg IMAG0375.jpg IMAG0376.jpg IMAG0377.jpg

Some more pictures!

We are planning on running 7 servos
  • Rudder
  • Elevator 1
  • Elevator 2
  • Aileron 1
  • Aileron/Flaperon 2
  • Aileron/Flaperon 3
  • Aileron 4

We are running all standard size servos, will a 4A BEC be enough?

Thanks
 
#8
Maiden

[video]https://drive.google.com/file/d/0Bx8RKasKz_WBSy0tNFpMMldDWlU/view[/video]

Any idea what the issue is?

Luckily its a small fix, only firewall came off.
 
#9
check the video

Maiden

[video]https://drive.google.com/file/d/0Bx8RKasKz_WBSy0tNFpMMldDWlU/view[/video]

Any idea what the issue is?

Luckily its a small fix, only firewall came off.
Looks like the rudder might have been reversed.

Check the video at :04, the rudder is full right
 
#10
Looks like the rudder might have been reversed.

Check the video at :04, the rudder is full right
I completely agree, there must have been an issue with the rudder, since we did check the direction of the rudder. Unless there was a full right input. I think there could have been an issue with the string we used to tighten the rudder, we spent a while on it when we tried to get it working, but i fear it may have been too slack.
 
#12
https://www.youtube.com/watch?v=dp3-4A4xTnM

Flew decently, only 20s of flight though, rudder needs more coupling with the aileron and the plane is having difficulty in turning right.

Very under powered, needed 100% throttle to fly.

In the crash we only damaged the under carriage, needs some repair but not as much as the first crash (reattaching firewall and front area of the firewall).
 
#14
I think you need a bigger vertical stabilizer on it so it won't fall out of turns.
The original designer of the plane also thought this as well.

We have now repaired it and roughly doubled the size of the vertical stabilizer and enlarged the horizontal as well.

We also switched from the 4250 500kv on 4s to a 6364 245kv on 10s, effectively doubling the thrust.

In short it didn't do much.

The plane immediately goes into high alpha, and refused to turn.

Unfortunately I don't have any footage to show you but the problem seems to even worse than last time and we are out of ideas to what caused the issue. I am beginning to suspect CG could be a problem.
 
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#15
She lives!

We made a new fuselage after the crash consisting solely of metal arrows joined by string soaked in PVA.

We also made a "wing box" so we can adjust the angle of attack easily, the Tail surfaces also significantly increased in size.

13570069_1711702059078403_1970406187_o.jpg 13570160_1711702065745069_546667003_o.jpg 13570221_1711702052411737_52592605_o.jpg 13589252_1711702049078404_302628264_o.jpg

The maiden went much better, as the gear actually tracked straight this time so take off was much easier. The aircraft is clearly overpowered, and we only needed less than half throttle to get her airborne. We even managed a down wind landing (although this wasn't intentional!). We need to sigificantly increase our control authorities for the second flight but its all looking up after all the issues we had!
 

PsyBorg

Wake up! Time to fly!
Mentor
#16
It may be my eyes or an optical illusion in the pictures but it seems to me that your wings are not 90 degrees with the fuselage and that the elevator is not parallel to the wings. That will cause all kinds of weird behavior as well if I am in fact seeing this correctly.
 
#17
Video


PsyBorg you could certainly be right, on the tail we are simply using a carbon fibre rob as a 'skid', which means when it's resting on the table it tilts to one side and flops all over the place. We are not 100% sure if it is parallel to the wing either....
 

PsyBorg

Wake up! Time to fly!
Mentor
#18
After seeing that take off it is very obvious. The right side main wing has a serious droop. The elevator and the rudder seem to be pretty well perpendicular with the fuselage the way they should. Investigate the main wing and get that up where it needs to be and I think you will have another advance in how it fly's.

As for the flight a little more air speed and more practice with coordinating turns should make it look a tad more graceful. It seems to float pretty well. That was a nice recovery after that turn too!
 

quorneng

Well-known member
#19
Apart from the rudder issue have you moved the wing back a bit?
It does seem to have a long nose and shorter tail than the full size both of which would effect the directional stability which was already pretty marginal as it had a rather small all moving rudder and it relied entirely on the rear fuselage side area for directional stability.
The later E3 version actually increased the length of the rear fuselage - I wonder why? ;)