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Oct 06, 2017, 01:03 PM
Registered User
Quote:
Originally Posted by JohnM
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.
what im failing to understand is why if i balance it at 1" from the firewall (making it more tail heavy) it flies much better. but if i go closer to the recomended 1.75" (i tried 1.5) its horrendous.

Should i add even more weight in the nose to get to the 1.75"??? from my understanding that once you get too tail heavy its garrenteed to crash but at 1" i was happily flying circuits and figure 8's although holding up elevator was making it difficult. It flew better aswell at slower speedstail heavy.

When i say slow, i mean not so slow its stalling, i can throttle back to below 50% and it still flies. and it glides fairly well and will land without suddenly rolling over.

when i say its slow i just mean that i dont think its flying very fast at full throttle so i have a tendancy to be sitting at high throttle not that theres not enoughs peed to keep it in the air
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Oct 06, 2017, 01:57 PM
Lifetime Member
JohnM's Avatar
A tail heavy plane will be difficult to impossible to control the pitch of the aircraft as it would be extremely sensitive to elevator movement. A nose heavy plane will require more elevator throw to change the pitch of the aircraft. It does not sound like added weight to the nose will help you.
If your CG measurement is accurate, then please try my no power glide test suggestion above .

Also, do you have another ESC to try. You may not be getting full throttle out of your SimonK ESC as it may have been software flashed to provide specs for a multirotor.
Oct 06, 2017, 09:56 PM
HZ Super Cub
Grauwulf's Avatar
Stick with it mate, the Arrow is an awesome little wing! I need to build another one at some point.
Oct 07, 2017, 02:16 AM
Registered User
The ESC is a minor issue at the moment, its like like its crawling by at full throttle. it has speed its just not as fast as i thought it would be but i am using the recomended motor for slower FPV flight. As much as i like the FT articles, they should be a bit more indepth about the motor setups. i cant see how changing from an 1806 2300kv motor to a 2204 2300kv motor without uping the prop.

The motors not getting that warm as far as i can tell so maybe i could go to 7x4 prop it is a tiny motor though.

also reluctanct to switch over to my 18a esc which is a YEP (which is used in my trex 250 currentlys shelfed) as it will reduce the weight in the rear.

Ill try a glide test, so do i just chuck it with no power and see what it does? if it noses to the ground its nose heavy? If it ??????? its tail heavy. I searched glide test and theres whole tone of posts with inconclusive information.

One thing i will say though, is its actually fairly easy to land (if i wasnt having to hold up it would have been much easier) i was able to fly it towards myself slow enough that i wasnt worried about flying into myself and get it to land on the grass not too far away from me (before i belly floped it on the runaway)

I did find my original setup guages (had to make new ones as thought id lost them) and it looks like maybe the angle on the elevon setup guages is different, the original looks to have more of an angle.

Now onto the servos, the were cheapy 2 servos 0.8kg torque, thats enough right>?

Going to buil another one but remove the paper from 1 side of the foamboard and see what kind of weight saving i get, i worked out that the paper could be 50% of the total weight based on a square i cut out and scales i used (whic are crap at low weights)

Ok that might work! if im right thats 42 grams less weight taking the arrow down closer at 283G. The target weight without battery is 170g which is quite difficult. Im sure even people using the DTFB or FT stuff struggled with that.

If i remove paper on both sides and tape on side i think maybe the way to go on this and use filimiant tape as strapping to reinforce the join :-) I think that will get my weight down.

Edit:

Ive started a seperate thread in the wing forum (didnt realise there was a dedicated forum to wings) . Thanks for the help ive got a few things to test out to hopefully get things balacned and trimmed out.

Normal posting will resume here soon
Last edited by bazsound; Oct 07, 2017 at 08:24 AM.
Oct 07, 2017, 06:58 PM
Registered User
Just realised im running a slowfly prop on this... would that possible hidner performer ? i know sf props are meant for lower KV motors to give more thrust. maybe the prop is flexing at high rrpm and that would explain the minimal difference between just over half throttle and full throttle.

ive ordered new props non sf this time .
Oct 07, 2017, 08:12 PM
Lifetime Member
JohnM's Avatar
How flexible is the slowfly prop? Do you have any other props to try?
Without a tachometer to check the RPMs of the prop, there isn't any way to confirm if you are getting full throttle from your ESC. I would swap the ESC just to rule that out.
Oct 07, 2017, 08:16 PM
Registered User
Quote:
Originally Posted by JohnM
How flexible is the slowfly prop? Do you have any other props to try?
Without a tachometer to check the RPMs of the prop, there isn't any way to confirm if you are getting full throttle from your ESC. I would swap the ESC just to rule that out.
Ive got some regular 6x4.5 props on there way

It looks pretty thin, i took a chunk out of my prop landing on tarmac.

Compared to my 1500kv motor on my profile yak, the 1806 is definatly spinning much faster. I do have another esc to try but again its low on the prioritys list.

The question still remains, would a slowfly prop show redcued performance on this kind of setup.
Oct 08, 2017, 02:22 PM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
Baz, a SF prop at these RPM's will defiantly twist and probably loose quite a bit of thrust.

However......

Wings are amazing bits of kit, walking speed to scare the out of you in the twinkle of an eye. Rolling like a drill bit or smooth and stable like a trainer, it's all there in one package but they do have a drawback.
Due to no tail moment or nice stabilising elevator to dampen things down changes to the C of G, incident angles (up-trim) or thrust lines have a far more marked effect. The wing itself will work like a huge brake because you can rotate it (increasing the angle of attack) very, very quickly, speed drops like a stone and she flies like a lead pig. Getting the balance between up-elevator, thrust and C of G will take more testing than a conventional lay-out. You have already found out how the amount of up trim required (creating reflex) varies greatly when the C of G changes.

Keep having fun.....

Paul

Oct 08, 2017, 02:27 PM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
PS, well done on the backwards prop. EVERYONE who ever flew a pusher does this, generally only once (OK, I can remember 3 times that I have done it) and you have got it out of the way in week one. One less problem for the future (wait until you do it after you have been flying the model for a few years and see how much head scratching and re-adjusting that you will do till the penny drops).
Oct 09, 2017, 02:43 PM
Registered User
So CG set to 1.75 " back from the firewall and elevons with a degree more of reflex, hand launched without a fuss. no sudden dive to the ground just calmy flew straight till i got the controls.

I used probably about half the availible trim and it was flying level, some aileron trim aswell.

2 5 minutes flights with no issues. landing was easy just glide in low throttle and when low enough cut power and pull uo to keeo level. sets down bice and soft
Last edited by bazsound; Oct 09, 2017 at 06:19 PM.
Oct 09, 2017, 04:48 PM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
Quote:
Originally Posted by bazsound
So CG set to 1.75 " back from the firewall and elevons with a degree more of reflex, hand launched without a fuss. down sudden dive to the ground just calmy flew straight till i got the controls.

I used probably about half the vailible trim and it was flying level, some aileron trim aswell.
Errr, totally incomprehensible, good or bad?????

Oct 09, 2017, 06:21 PM
Registered User
edited
Oct 10, 2017, 06:08 AM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
Quote:
Originally Posted by bazsound
edited
Thanks, I had had a beer but really couldn't decipher that......

Sounds good, like I say, wings are a bit of a delicate balance, too much of any thing (or too little) with a slightly off C of G and 'yer Butt gets bit......

But when you get it right.....


Oct 10, 2017, 07:48 AM
Registered User
Quote:
Originally Posted by PaulB
Thanks, I had had a beer but really couldn't decipher that......

Sounds good, like I say, wings are a bit of a delicate balance, too much of any thing (or too little) with a slightly off C of G and 'yer Butt gets bit......

But when you get it right.....


Ive removed 5g of weight for the next flight, unfortunatly the heavens just opened up so no flying today .... when i did the dive test it was pulling out of the dive so i guess that means nose heavy.
Oct 10, 2017, 10:43 AM
Registered User
My new props came so had enough time to set them up and briefly test,. TBH i cant tell much difference they actually seems a bit thinner than the SF props. they are mared 8x6E and the blades arnt as wide.

Anyway decided to look at throttle endpoints, increased from 120 to 140 and there was a definate increas in RPM.


Pretty confident this will take of vertical with easy. i sat it in my living and wacked full throttle, it lifted 4-5 inches before i cought it :-0


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