flitetest mini arrow - RC Groups
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Sep 09, 2017, 02:27 PM
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Build Log

flitetest mini arrow


my mini arrow build

someone at my local flying club recomended checking out flitetest foamies as they did kits for pretty cheap. Seen that they also had free plans and since i had a spare sheet of foam thought ill just build something. Ive always liked the flying wings so thought the mini wing would be a nice small delta type wing to build and the method used in the plans made a really nicely shaped airfoil.\

well this doesnt actually fit on 1 A1 sheet. I had to get another sheet to do the wing spars and a couple other smaller pieces.

Anyway i was surprised at how well this turned out despite the poorly cut out and taped plans (things didnt seem to want to align perfectly) .

One thign that really annoyued me was once i had both wing sections glued together noticed that 1 of the wings is missing a fold on 1 out of 3 of the crease lines... it doesnt really change the airfoil shape though.

havnt got electronics for it yet so wont be maidened for a week or 2. another great thing about this wing is the relative low cost of electronics. I may look at using a slightly higher power rated motor with a larger prop. Since inm using heavier foamboard. Although it will probably fly fine on the recomended motor.

my yak 55 which i built out of the same foamboard came out at 350g flying weight, comparing that with others who are down as low as 140g.
Last edited by bazsound; Sep 09, 2017 at 02:36 PM.
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Sep 20, 2017, 05:59 AM
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Almost 2 weeks and no work yet done to finish this. Still trying to decide on weather to make the FT controls horns or to use the plastic ones i have (they need to be glued onto the surfacerather than being isnerted into a slot)

im still waiting on 2 frsky micro recievers on the slowboat from china, almost 2 weeks now...

also deciding on wether to use piano wire or to use CF rod and some scrap control rods as ends.

Also cant decide what motor to use, my build is going to be heavier. its already at 170g before adding electroinics. add 10g for servos, say 30g for motor, 50g for battery round up to 100g so 270g AUW.
Sep 22, 2017, 06:52 PM
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last pieces of the uzzle ordered, motor servos pushrod stops (did add rods but they were only availible in global warehouse so cancelled)

just need my frsky recievers to turn up i orderd 2 weeks ago from bangood.
Sep 30, 2017, 07:24 PM
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frsky dr8 compatible recievers arrived today, been waiting almost 3 weeks. Ordered from banggood because they were cheap (6 gpb)

Man didnt think they would be that small! these things wouldnt be out of place in something a 10th of the size of my mini arrow... the heads for servo connections came serperate so you have to solder them yourself, means you can decide of you want hardwared to save weight without having to desolder.

Should hopefully have it flight ready monday or tuesdsy depending on how well it balances and if i decide my poorly made control hors are good enough.
Oct 02, 2017, 03:59 AM
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Had a spare hour to get things ready last night. My 30A "Simonk" ESC is a bit overkill it wouldnt fit int he powerpod until i removed the heatshrink and then it fit at an angle just...

Had to use servo extension leads as the servos had short wires that just came to the hole in the electronics bay..

Only remaining thing is to make up the control horns which ill use BBQ skewers with an old piece of metal control rod (think it was my trex 450 tail rod heatshrink and CA'd in place.

Now, the "SimonK" speed controller. This was a suspiciously cheap ESC from ebay from a sellar registered in HK but advertising there items as within the UK. It took over a week to arrive pretty sure it did not come from UK. Anyway/

ive only tested it briefly, i noticed that the motor does not start spinning until an inch or so of stick travel, so thought OK just calibrate the throttle. Guess what happens, Motor bursts into life if you power on at full throttle....

Oh... and total weight has now rocketed to 320g..... downsizing to a 15A esc will only save a small amount of weight.Im wondering if i can go up a prop size without over working the chinsey little motor
Oct 03, 2017, 05:51 AM
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no need to up a prop size. succesfully flew the arrow finding it a bit slow.. turns out i had the prop on backwords.

waiting in a break in the windto test it. not really wanting to try handlaunching unless its notso gustt. last flight broke the stabilisers and a few glue joints when it got coufht and sent cartwheeling along the groynd
Oct 03, 2017, 05:54 AM
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some pictures. love the power pod idea. Name: IMG-20171002-WA0000.jpeg
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Oct 03, 2017, 09:57 AM
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Im going to build another one, except with 1 layer of paper removed and using gorrilla glue where i can. See if i can get it under 300g the hobbycraft foamboard i have.

Excited to see it flying again with proper thrust!!! I trid today but it was too windy, sent it cartwheeling again.
Oct 06, 2017, 08:35 AM
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Finally got to test out the mini arrow with the prop on the correct way. I had also rebalanced it as im sure its nose heavy, moving the battery backwords. Reset my trim.
First flight almost hit the ground as i ended up giving TONS of up elevator, during the flight dialed in trim but still found that i was always holding up elevator..

Made a CG stand today and checked it, still looked like it was nose heavy. So taped a 1p coin to each stabiliser which shifted the cg back a little closer. Still felt nose heavy.

So ive added a coin and according to my stand its now slightly tail heavy with the cg at about 1inch from the firewall... We will see how that flys once i go back up the flying field.

It still feels really slow even though it feels like its got more push.

I also find i dont have enough throw. Icve used the 12 degree gauge and im getting that at full rates. but it still rolls really slow. I hjad to reduce expo from 30 to 0 because i was using alot of stick for just normal flying
Oct 06, 2017, 11:15 AM
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JohnM's Avatar
Sounds like you are still much too nose heavy if you are having problems with roll rate. A wing of that size should roll like a drill bit.
What size motor is that and what kv?
Prop size?
Battery?
What is the weight without battery? Advertised is 170gm
Oct 06, 2017, 11:46 AM
Registered User
Quote:
Originally Posted by JohnM
Sounds like you are still much too nose heavy if you are having problems with roll rate. A wing of that size should roll like a drill bit.
What size motor is that and what kv?
Prop size?
Battery?
What is the weight without battery? Advertised is 170gm

1806 size 2300KV motor running a 6x4.5 prop on 3S 850mah .
Im really confused at which way to go ont he CG. I rebalanced the plane to balance on the CG mark, it flew like crap and i didnt have enough up elevator trim. Reset and put it back to about under an inch infront of the firewall, it flew much better but still needed lots of trim and fly holding up elevator to stop crashign into the ground.

unfortunualty when i came into landed, i bellow flopped it ont he runway and broke stabiliser and took a chunk out of 1 wing (easily repairable though)
Oct 06, 2017, 12:01 PM
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JohnM's Avatar
I am not familiar with this wing but is the bottom flat or does it also have an airfoil? Is the motor supposed to be mounted with any down thrust angle. With the motor at the rear, the motor angle should be up, I believe, correct me if I am wrong.
I would try launching it level under no power and check the glide path. Keep adding weight to the rear (near the center line, not the wing tips) until it glides well. With a delta wing, I would recommend adding a slight up trim (reflex) to both elevons in the neutral elevator stick position.
Oct 06, 2017, 12:11 PM
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JohnM's Avatar
That motor size is probably too small as well and is causing a lack of power.

From the Flite Test site:


FT MIGHTY MINI ARROW SPECS

Weight without battery: 6 oz (170 g)
Center of Gravity: 1.75 inches (44 mm) in front of rear firewall
Control Surface Throws: 12 ˚ deflection (elevator/aileron/rudder) Expo 30%
Wingspan: 29 inches (736 mm)
Recommended Motor: 2300 kv 2204 size motor
Recommended Prop: 6 x 4.5 prop
Recommended ESC: 12 amp minimum
Recommended battery: 800 mAH 2s or 3s
Recommended Servos: (2) 5 gram servos
Oct 06, 2017, 12:21 PM
Registered User
Quote:
Originally Posted by JohnM
That motor size is probably too small as well and is causing a lack of power.

From the Flite Test site:


FT MIGHTY MINI ARROW SPECS

Weight without battery: 6 oz (170 g)
Center of Gravity: 1.75 inches (44 mm) in front of rear firewall
Control Surface Throws: 12 ˚ deflection (elevator/aileron/rudder) Expo 30%
Wingspan: 29 inches (736 mm)
Recommended Motor: 2300 kv 2204 size motor
Recommended Prop: 6 x 4.5 prop
Recommended ESC: 12 amp minimum
Recommended battery: 800 mAH 2s or 3s
Recommended Servos: (2) 5 gram servos
Theres 2 recomendations for motors. the 1806 motor for slower FPV flight and 2204 for faster racing, but thats as far as they go. both motors are 2300kv so i dont get how one can be faster than the other without changing the prop.

However i now see it will effect the balance, as if your using the FPV motor which is smaller you need more weight in front (with FPV elevtronics) and with the larger rear motor with no extra fpx gear and it will balance.


I just dont get how im seeing different flight characteristings, the design calls for no thrust angle, the power pod is made from foam and a firewall glued directly to the firewall, normally in there other desings there is thrust angle but for the wing they say none is needed.

I am on the heavy side though, 170g with no electrnoics. flying weight is 325g, it hink most people are around 250g
Oct 06, 2017, 12:56 PM
Lifetime Member
JohnM's Avatar
The smaller 1806 motor may not be able to provide ample power (airspeed) for the higher AUW of your plane. Think V8 versus I4 engine. They can both provide high speed but the V8 has more low end torque.
You might want to try a 5x3 prop.


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