Saturday, 19 December 2015

Simple 3 channel trainer

This design was inspired by a friend who wanted to take one of my "retired" planes to learn how to fly. So I gathered bits and pieces together and tried to come up with an easy to fly, crash proof trainer.

It only has rudder elevator and throttle, no ailerons. I wanted it to be as light as possible for slow and easy flight with a big energy absorbing nose and a tough fuselage.



The fuselage was shaped from a 50 x 100 x 370 block of XPS insulation foam and the tail planes are 8mm panels of the same foam. The boom is a Skyshark P4X 7.6mm tube.

The hotwire-cut 170mm clark y wing comes from rescued sections of the drowned Fokker (which now has new wings) Three x 360mm sections were glued together with the tips each raised 120mm. No spars are needed to hold the polyhedral due to the tape covering and large join surface area for gluing.


The nose is soft packing foam covered with tape and completely encases the 1300mAh Lipo battery.

The motor is the original Bixler 2, servos are cheap 9g HXTs, and it has a Plush 18A ESC and HobbyKing 3 channel receiver.

All up weight with the battery adds up to 550g, giving a slow continuous cruising flight time of over 30min.

This plane is very smooth and stable and with correct trim will fly hands off.

At this stage the nose, fuse and wings are almost bullet proof, but the tail planes are a bit too delicate. Thinner sheets of XPS foam are quite brittle so some kind of reinforcing is needed.  Both the elevator and rudder have cracked during the test flights so I have added a 0.5 x 3mm CF spars.

Might be better to use depron or corflute for the tail.


Dimensions



Flight video - motor slope soaring

Build video


UPDATE 30 March 2016 

After some tough flight testing by my dedicated student test pilot it became apparent that this tail
design was not crash proof enough.

So here is the new tougher tail design made from depron. The tail to boom join has extra foam fillets either side for more gluing area and to raise the elevator a little.

The new wing has more area and less polyhedral for smoother flight.


Update overview video

Tail build video

Dimensions for the updated tail design






MATERIALS
New Stuff iron-on film - EZload laminate - http://www.neopostonline.com.au/lamination/ez-load-roll-film

BUILD VIDEOS


25 comments:

  1. Where is the battery location

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    Replies
    1. I should have been patient and waited for the video

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  2. Replies
    1. About 40mm from leading edge, but it seems to be very forgiving

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  3. Wow! This does appear to be a very durable, and easy-to-fly trainer with the dihedral on the wingtips. Well Done!

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    Replies
    1. Thanks Stefan, seems to handle strong wind well too.

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  4. Hey Andrew!
    Wonderful blog, I've been watching, reading and learning so much. I've built and crashed a number of planes, really need to find something that I can keep in the air (would add so much to the hobby!). So planning on building this, just a couple of quick questions.. 1) In the video you mention that the tail is a CF arrow but then in the materials list it seems to be a kite spar from the US. Are the two interchangable? 2) How do you adjust CG? The battery seems kind of fixed in the nose? Cheers, Andy

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  5. Hey Andy,
    1. Correct, arrow shafts are often used as kite spars. The Skyshark P4X is both.
    2. I designed this one to be correctly balanced with a 1300mAH right forward in the nose. So the CG doesn't need to be shifted. If I needed to move CG forward I would add some big metal washers in with the battery.
    Goog luck with the build. Let me know how it goes.

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    Replies
    1. Thankyou so much Andrew, I'll keep you posted. Love the video's of the slope soaring by the way, I'm in Melbourne so I can't wait to get my skills up sufficiently that I could attempt it myself. Cheers, Andy

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  6. Retractable landing gear for model aircraft with his hands
    http://petliavia.blogspot.com/


    Homemade hinges for the plane with their hands
    http://petliavia.blogspot.com/

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  7. Brilliant plane, I'm having a go for my first build.

    What prop, motor and esc did you go for?

    Keep up the good work, great videos.

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  8. Introduce yourself and I'll answer all your questions

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    Replies
    1. I'm based in the UK, interested in building my first plane. No previous experience at all - saw Flight Test and that got me inspired, looked around for my first build but was much more interested in hotwire and foam than bending bending board so was drawn to your YouTube channel.

      I've made a hotwire cutter, templates and cut out some wings. I've made a fuselage and gorilla glued a carbon rod in and I've used your design for the tail which has servos in and seems to be working fine.

      Now I just need to mount a motor and the electrics ... and be brave enough to try and fly it!

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    2. James that is fantastic, you're jumping in the deep end like I did. This plane is best with a small motor like a Turnigy 2822 1400kV from Hobby King and a 20A ESC. 7x4" prop works well. You will have the best chance of success if you keep it all as light as possible and make sure the CG is about 25% back from the leading edge. Good luck and let me know how it goes.

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  9. Hi Andrew,
    My name is Pete. I wish to help friends in Central Africa who run a game lodge. They need a basic flying camera platform for wild animal and intruder/poacher monitoring. Postage/Freight is very expensive and problematical. They only want to bring in high value items and build/repair as much as possible onsite. They are very good bush mechanics/builders. I want to recommend this trainer as a starter project.
    They have a preference for a fuel driven engine. Do you think the trainer will work with a fuel driven engine?

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    Replies
    1. Hi Pete, I don't have any experience with gas motors but I can't see any problems. Would be best to scale this plane up a bit to carry more weight, and find a stiffer tail boom for less flex. But this is a very forgiving plane to fly and a perfect learner plane.

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  10. Hey Andrew,

    This is the same Mark that has been asking you questions in your youtube comments, but since these are specific to this plane I figured I'd put it here:
    - is the airfoil of the updated wing still a clark y (I noticed the wing doesn't fit in the original saddle, there's a gap there)?
    - what is the angle of incidence of the wing? Upthrust on the motor? Any thrust to either side?
    - is there anything you would change with the latest iteration of this plane to make it better?

    Yes, I overengineer everything... ;-)

    If you're interested I may do a sketchup drawing of it before I build it, not that I need to to build this, but mostly because I've been looking for things to draw to get practice at it.

    LOL, I really over engineer everything.

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    Replies
    1. Hi Mark,
      - Clark Y airfoil, I lifted the leading edge up on the mount because it needed lots of up elevator so it seemed to need a few degrees of positive wing incidence.
      - Motor thrust is angled down though the CG point (roughly) and no right or left angle. The mount is aluminium and can be "adjusted" by brute force in the field.
      - The latest version is just right so I wouldn't change anything.
      - Please feel free to do a sketchup drawing, I'd like to see it.
      Can email me at apnewton@gmail.com

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  11. Hi,

    I like your Videos. Simply great.

    I am new to this hobby. I want to build pusher plane like this.

    But I am not sure how to set up motor & prop rotation.

    When looking at the motor, ( from the back of the plane ) since this is a Pusher, Please tell me which of these options is correct ?

    1. Motor Spinning CCW & Pusher Prop ( CW Prop or Right handed prop ) Numbers facing front of plane ( LE of prop on left hand side )

    2. Motor Spinning CW & Pusher Prop ( CW Prop or Right handed prop )

    3. Motor Spinning CW & Puller Prop ( CCW Prop or left handed prop )


    Please revert back as it would help me a lot.

    Thanks for sharing your knowledge.

    Happy flying.

    Best Regards.

    Amit

    ReplyDelete
    Replies
    1. Hi Amit,
      I don't think about CW or CCW props anymore.
      Just make sure the numbers on the prop are facing towards the front of the plane, doesnt matter what sort of prop.
      Rev the motor a little bit and if it spins in the wrong direction all you have to do is swap any 2 of the 3 ESC wires.

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  12. Hello Andrew,
    I have made a start on the cutter. Got the frame built, just got to add switch and power it up and get some foam.
    Can you confirm aerofoil section. In the update video you recommended Clark Z but Clark Y is mentioned in answers to some blog Questions. Is there a major diff between the Y or Z? I have already cut a template for Z Cheers Peter

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    Replies
    1. Both will work Peter, for model planes it really doesn't matter. The Clark Z has a flatter base so it's easier to mount.

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