FTScratchBuild
The FT Spear is Flite Test’s newest wing aircraft! The Spear is designed to carry everything you need in a reinforced, lunchbox-like compartment.
The Spear and is made from four pieces of foam board, and it can be built in less than 2.5 hours when using the speed build kit.
Before starting the build, center your two servos and build your power pod. This power pod is not swappable, but it does use an A fold similar to other FT builds.
Don’t forget to test your motor to make sure it’s moving in the correct direction.
Next, build the wing assembly. There will be four spars, two for the wing and two that will be used in the center section.
Once the wing assembly is complete, build the center section. Install the two remaining spars inside the center section. After the center section is built, attach it to the wing assembly.
Install your elevons, your centered servos, your control horns and your push rods.
Connect the rest of your electronics and adjust the rates on your receiver. After your electronics are installed and tested, build the wing tips and attach them to the wing assembly.
Build the FPV pod, and remove the foam from the nose along the score cuts. Install the FPV pod inside the newly removed portion of the nose on the center section.
Test the CG and make any necessary adjustments. Install your prop, and you’re ready for the maiden flight!
FT SPEAR SPECS
WEIGHT WITHOUT BATTERY: 1.45 lbs (658 g)
CENTER OF GRAVITY: 3 – 3.5” (76 – 89 mm) in front of firewall
CONTROL SURFACE THROWS: 16 ĚŠ deflection – Expo 30%
WINGSPAN: 41 inches (1041 mm)
RECOMMENDED MOTORS: 425 sized 1200 kv minimum
RECOMMENDED PROP: 9 x 4.5 CW (reverse) prop
RECOMMENDED ESC: 30 amp minimum
RECOMMENDED BATTERY: 2200 mAH 3s minimum
RECOMMENDED SERVOS: (2) 9 gram servos
PICK UP A SPEED BUILD KIT HERE!
FT SPEAR PLANS
STORE LINKS
https://store.flitetest.com/ft-spear/
https://store.flitetest.com/power-pack-c-fixed-wing-large/
New to the R/C hobby?
Here are some resources to help get you up to speed!
Beginner Series: WATCH HERE!
Electronics Setup: WATCH HERE!
First Flight Quick Tips: WATCH HERE!
Scratch Building without Knives: WATCH HERE!
Got glue?? Get Some Here!
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I got a lot confused building the center cover because the video shows two pieces being assembled while the scratch plans show a single piece. Perhaps this was a change made after the first run?
Lastly, why are there 2 CGs shown on each wing on the scratch plans (pages 7 and 14 on the tiled plans)? Which do I use? Or am I supposed to use them together because wings are so hard to balance?
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Scott
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Your effort to advance the hobby is impressive.
The spear is a great design and comes together well. I am already on my second build.
Keep up the great work promoting the hobby.
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I ran some bench tests with a NTM28-26-1000kv short shaft and 30A ESC. All I had for the test was an almost discharged 4s-3300. A stiff 8x6 prop gave a peak current of 12A... Low if you ask me, and your numbers should be close to that... The KV difference being compensated by the difference in pitch.
I recommend an 8x6 or similar with your 1200kv motor on 4s.
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8x6 props make significant difference, setup works great. Also, thanks for plans.
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Thank you
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RECOMMENDED MOTORS: 425 sized 1200 kv minimum
RECOMMENDED PROP: 9 x 4.5 CW (reverse) prop
RECOMMENDED ESC: 30 amp minimum
RECOMMENDED BATTERY: 2200 mAH 3s minimum
RECOMMENDED SERVOS: (2) 9 gram servos
Basically a c power pack with a different prop. I included the reflex as well. What would you guess the glide ratio for the spear to be?
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For stronger wings, especially if you extend the the wing span, coat the foam wings in a gelcoat or fiberglass. I don't know how this particular foam might react to gelcoat or fiberrglas, so be sure to test on a small piece of foam before proceeding. You might want to beef up the spar, if you go much wider. I built a amall (12"-18", can't remember for sure) delta wing(no engine or 'cockpit area) with adjustable pitch, as a class project to demonstrate the effect of wing pitch & stalling by pinning 1" lengths of yarn all over the wing then mounted it outside of a car & drove down an access road & took pictures of the yarn at different pitch angles until the wing 'stalled' as noted by the yarn no longer following the wing flow. I used balsa wood for the wing layout & green foam between the balsa wood wing design & 'sanded' it smooth the the wing layout pieces using foam to sand it smooth. Using foam to sand foam works great as sand paper would quickly 'fill' with the 'foam dust', but be warned, it creates a terrible 'foam dust' mess. GOOD LUCK & BLUE SKIES!!
Eddie H.
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Just to clarify, I'm taking the CG reading at the wing root / leading edge, attached you will find a picture of the electronics arrangement while trying to get the CG right.
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It feels to me like there isn't enough "wing area" to maintain a good glide ration. Any thoughts from the experience pool?
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After reading all comments, I don't know witch prop and motor to chose.
I chose these parts, but are they good ?
- Turnigy L2210C-1200kv
- ESC 30A UBEC/3A
- APC Propeller 10x5
Thx for this awesome plan ;)
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https://youtu.be/BngZwJ0_BDA
https://youtu.be/S-AVs-6xp1w
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Here's my very first build album... a little rough and ugly with the extra glue, and a few noobie techniques that i will change on the next build (FT Explorer), but despite some of the rough looking seems this baby feels pretty tough.
https://photos.app.goo.gl/eWbYZa93gsKHYOTc2
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https://www.youtube.com/watch?v=zx8NBu1a0bE
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