40" Trainer Scratch designand build.

[ViperTech]

I like to build and fly! I wanted a little bit larger trainer plane. I also wanted to understand more about the design process of a plane and how much wing size to fuselage size to tail size to horizontal stabilizer size affected the plane and it's use /performance. I found some good information on the web and started this plane design and build. I used window's7 paint program, because you can adjust the work space to the exact size of the DTFB and it has a grid function that made it easy for me to use. I know there are 3d programs out there but I'm old school and I want to get building.
So here is the design.
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The fuse is 30" long Wing is 40" span 8" chord
The design will print actual size of all parts, the wing is made from 1 sheet of DTFB huge wing from a 20x30 sheet!
Some design elements, the battery loads in the top of the fuse in front of the windshield and can accommodate a 2200 mah 3s battery, I made a removable hatch for it. The reason for this is so I don't have to flip the plane over to change batteries and risk tail damage. The esc is in a compartment below the battery and I have vent holes in the bottom plate to cool it. That makes an easy connection for the battery and I run the control wire to the RX that is up in the space below the wing where I have a shelf/former placed, that keeps RX away from the high current and RFI of the battery and motor. The landing gear is placed as close to the LE of the wing as it should be for a tail dragger. The esc is 40 amp and the motor is a HK Donkey ST3007 1100 Kv and it will have a 10x6 prop and of course 9 gram servos. The wing mounts on the fuse in a pocket area I designed into it and will be held on with rubber bands and bbq skewers.

This plane is almost finished and I will get video of the test flight.

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[flying pancake]

wow, looks very very nice
are u going to paint it?
also i think it would look good with balloon tires and a litle bit shorter landong gear
nice work dude!
i am hoping it will work out!

 

[ViperTech]

Yes I will paint it and as for the LG I would like to go with 3" tires but not in the budget right now, the LG height is needed for the 10 inch prop to keep clear of the ground.

 

[rcspaceflight]

It looks great! :applause:

Not to nitpick, but the nose looks too long. I've always been able to get away with shorter noses, but then again I use a 2200mah 3S battery. I don't know what size battery you fly with, but you may need the extra nose length for proper CG. The long nose doesn't look bad cosmetically. It actually looks really nice. It just looks unnecessary.

 

[pgerts]

;-----) Long nose - take a look at the Turbo Porter.
If you balance the motor with servos close to the rudder and elevator you can put any battery in the CG without problems.

 

[ViperTech]

It looks great! :applause:

Not to nitpick, but the nose looks too long. I've always been able to get away with shorter noses, but then again I use a 2200mah 3S battery. I don't know what size battery you fly with, but you may need the extra nose length for proper CG. The long nose doesn't look bad cosmetically. It actually looks really nice. It just looks unnecessary.

Funny you mention that! Like I stated I was going by the design specs/ratios I found in my research and the distance from the LE of the wing to motor tip is 1 to 1.5x the chord so that would make mine need to be 8 to 12 inches, I opted to go 8" and it does look long but seems to be the correct proportion.

I made another attempt previously at a plane and it is tail heavy even with it's battery forward. Here is a picture of it.
It now has a bigger motor on it, my FT-22's 2826/10 1400Kv and that helps.

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Oh and FYI the orange and blue plane is a blast to fly! Really fast and moves quick! I named it the X'straparamental!

 

[Ron B]

Viper you have done it again and a nice looking plane at that. I like it's looks better than the orange and blue.
I have the formula that you do and when working with a new plan it is best to work with the old tried and true then vary from there afterwards.

 

[ViperTech]

Thanks Ron! The blue one was just built on a whim, I litteraly took a board a pencil and a ruler and drew it, trying to make a plane from one board with maxium wing span and fuse size. I didn't make it, needed about 1/2 a board more but I was close!

 

[ViperTech]

All finished!

Well as promised, it is finished!

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Some Specs.
40" wing span 8" chord KFM3 with 29" bamboo skewer and a 30" carbon tube
Ailerons and separate flaps
30" fuse 2 3/8" wide
HK Donkey 3007 100Kv motor spinning 9x4 slow fly prop
Battery can be 1300 to 2200 3s
AUW 29.95 oz.
3" wheels
Painted with Krylon Fusion for plastics directly on the paper!

Here is the maiden flight!

Sorry about me rambling on while flying I am just so happy with the result I sound like a little kid

 

[Ron B]

You are a kid just an older one ...... arn't we all?
looks good and flies nice what more could you want. Auto pilot landings? Hey as long as you take it home in one piece (with the exception of a broken prop) it is a great day. a little breakage its just a good day.
congratulations!!!!
paint some white or silver on the cabin for windows.

 

[ViperTech]

Ron , Thanks! It needs some fine detail work and windows are on the list, I'll most likely do black on the windows and I need to loose the green prop!