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May 01, 2020, 05:13 AM
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Build Log

mini Pitts s12


Hi all,
This is my first light and small plane, I've been always fascinated by the umx beast but don't want to afford the price, so I decided to built myself one.
They goal is to be as light as possible, I know that the best in the field are the profile planes but I hate the way they look. However I start from a profile like structure and add fuselage sections to provide some thickness. I choose the s12 because in my opinion is the best looking pitts and it is also the least complex to design with the round shape. Now some numbers:
span 70 cm
weight 250 g (120 depron only weight)
wing loading 35g/dm2

motor blue wonder 1700kv
prop 8x4 (hope to reach 300-350g of thrust as i read online)
2s 800 mah
1 servo aileron 9g
2 tail servo 6g
12A esc

Hope to begin cutting soon, Any suggestion will be appreciated Thank you
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May 01, 2020, 05:51 AM
Registered User
Light and small? Boy are you in the wrong subforum...

Anyways: with a WS of 700mm, you should aim more for 150g. On the other hand, this is a doubledecker... so it's not gonna be too fast. And I guess you have some of the stuff flying around already.

My suggestions: Dont know about the motor, but take a smaller prop, esc is ok. Smaller batteries ( I fly 260mAh 2s in my 700mm plane) and just to drive my point home: take the 6 g servo as aileron and take some 4 g servos for the rest.
May 01, 2020, 07:44 AM
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You are right I miss the correct subforum,
Thank you for the suggestions, I will move to foamies scratchbuild
May 02, 2020, 04:07 PM
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Finished to cut all the part and checking the dimensions. Looking forward to begin glueing tomorrow
May 03, 2020, 04:16 PM
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Some progress today, the fuselage is glued, ailerons e elevators are joint to their fixed counterpart. Supports have been reinforced with some balsa wood to avoid flexibility. I place the outer skin to adjust and trim it to the body. I prepared an engine naca with xps.
Last edited by Nitrox416; May 03, 2020 at 04:48 PM.
May 06, 2020, 10:54 AM
Space Coast USA
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1 aileron servo?
May 06, 2020, 12:51 PM
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Quote:
Originally Posted by hoppy
1 aileron servo?
Hi, the original plan was to made a single aileron servo but with real dimension in the hand I think that the fuselage is too large to operate smoothly, we will see.

My lhs is obviously closed now and I haven't a proper steel wire to make the gear, so I opted for a mixed carbon-steel ghetto gear hope that it will hold strong. now also the motor is attached together with the elevator
May 08, 2020, 03:09 AM
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Work in progress I tried the aileron servo layout and went for the two separate controls. I've glued the skin and the wings. The upper wing fuselage support are not well aligned with the outer one I think that in the future plans I will make it vertical.
Pretty satisfied with the overall fit of the part, not like a kit but good enough
May 08, 2020, 03:40 AM
Registered User
Very nice Pitts. Could you explain us how you made the gear. Mainly the connection between the horizontal and oblique parts. What are dimensions of used material (carbon I suppose). I am interested with your model because I am building a Tipsy Nipper Mk2 having similar dimensions. I have also ordered a like Blue Wonder motor.
May 08, 2020, 10:49 AM
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Thank you for the interest, basically they are carbon tubes 5mm outer dia 4mm inner then inside I glue inside a steel wire with the oblique extension with some epoxy hoping that it will withstand some landing, however if I had the possibility I would make the gear with a safe stell wire because there is barely no weight gain with carbon
May 11, 2020, 06:27 AM
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So the pitts is finished, i will wait the opening of lhs to buy some lighter wheels, right propeller and a proper spinner. The model is looking good however I miss something regarding the weight, during the build I constantly weight the parts to see the trend going towards what expected but somehow if turned out to weight 350g ready to flight. I surely shave some weight with wheels but not more than a few grams. Something had gone wrong hope that it will be a good sport flyier and not a flying brick.
Enjoy the photos, i will report the maiden
May 12, 2020, 02:43 PM
watch your head
Hi,
she looks great. Donīt worry about the weight. A biplane with 70cm WS can have about 500g and still flies great.
The upper wing seems to be a bit to far in front, so keep in mind, to balance the CG to about half of the upper wing for maiden.

Good luck and bring her home in one peace
May 20, 2020, 03:01 AM
UMX guy
SamFly's Avatar
Looks amazing! I've got the UMX beast and would be interested in building one of these to go along with it. Do you have a set of plans for it?
May 20, 2020, 06:28 AM
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Thank you guys looking forward to fly, these are the plans I modified something to take into account some modification,
They are not easy plans, feel free to ask anything.
cheers
May 20, 2020, 12:25 PM
UMX guy
SamFly's Avatar
Quote:
Originally Posted by Nitrox416
Thank you guys looking forward to fly, these are the plans I modified something to take into account some modification,
They are not easy plans, feel free to ask anything.
cheers
Ok, thanks for the plans! I have them printed out. What thickness of EPP did you use?


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