new learner needs help!!!

[ccwee]

hi,

i'm a new RC learner now taking over a project of making a ducted fan liked flying craft. however i can't make it fly in a controllable manner and would like to seek for advice.

below are the descriptions about the flying craft

fuselage:
1. material: plywood
2. control surface: 4 pairs (8 pieces) below the fuselage body
3. weight: 750g (body+electronics)
4. shape: doughnut shaped (diameter 30cm), with one propeller (13 inches, pitch 7) on top, 4 pairs of flaps below

electronics:
1. 4 JR DS 3301 servo motors to control the 4 pairs of flaps
2. 1 Futaba GYA 350 gyro
3. 1 Hacker B40 12L+4.4:1 brushless motor
4. 1 Hacker Master 40-3P controller
5. 1 Sanwa RX-611 40MHz 6 channel receiver
6. 1 Basic Stamps 2 (mix the gyro ouput and receiver output to control the 4 pairs of flaps)

The motor is able to lift the flying craft up and my task is to make it stable during the flight. however i need to clear some doubts before i can move on.

1. the flying craft is powered by a big power supply device at 13V 14A, is the motor being over driven? if i want to change to battery power supply, how to choose a suitable battery?

2. when it flies, it always tilt forward or sideward, what's wrong actually? how to stablilised it? i don't have pitch control, the 4 pairs of flap below are the only control surface i have.

3. should i change a lower pitch propeller instead? my primary goal is make it hover with counter torque balanced by the 4 pairs of flaps, is there any tecnique that can help to achieve this?

4. the gyro is used to sense any rate changes about the vertical axis, my control algorithm incooperate with BS2 works well when the craft is moved manually, but still haven't test for actual flight. any comment on this?

hope to get the reply asap as i need these info and advice urgetly, u can either reply me in this post or email me at kakiawee@hotmail.com. your kindly helping is appreciated. thanks

[Super-Hornet]

Do you have picture of your EDF craft?

It sounds like u are creating an airplane that can hover (can't remember the name for that plane) or u are creating a hovering craft for single personnel... like those jetpack.

Super-Hornet

[ccwee]

ya, it's something looks like the Cypher. the only different is that i have 4 pairs of flaps at the bottom of the fuselage but Cypher doesn't. i'll try to upload the picture of my flying craft

[PhiBeR]

Hi Wee,

Wenwei here, u meet me at Hall 15!
Please post more pics of ur setup so that we can give some comments!
also, u dropped a set of notes in my hall, let me know when u
wanna pick it up!

[Tele]

hi from what you have given us it very hard to make a judgement on what could be wrong. pic speak a 1000 words.

but my inital thinking is that this craft has no stability factor.
ie a plane has the stability of its wings to keep it up a heli has the stability of the momentum of the blades to keep it up ..this craft has no stability...if the body of the craft was spinning it may help or alternativly if you can hang some weight below the craft then it will have a centeral balance point from which to act and control it would act like a pendulum and centre the craft at 0 input. other wise you will need constant input on a very fast scale to keep this thing steady in the air. ( like balancing a marble on a light globe) as most things do not want to fly!

I hope this helps
looking forward to some pics

cheers doug

[PhiBeR]

I've seen the pics..
Let me see how to describe it..

Looks like a big ducted fan flying ufo..
Hacker motor in the centre with a 1070 APC prop..

kinda like a big donut with motor in the centre..
The control flaps are vertically down..

/ | \
|-o-|
\ | /

Looks something like that from the top.. visualise the prop blades..

[ccwee]

hi,
these are the pictures of my project

[ccwee]

another

[ccwee]

bottom view

[ccwee]

last

[Super-Hornet]

U might want to have 2 propeller running is opposite each other to cancel off the rotating effect.

If u look at Cypher design, it is actually consist of 2 propeller spinning in opposite each other.

If not, they u really need a flap at the bottom and the flap must be big to counteract it.... just like those 3D profile airplane.

Super-Hornet

[Art]

erm...where shall this thread be?!?!?heli or planes?!

[ccwee]

Originally posted by Super-Hornet
U might want to have 2 propeller running is opposite each other to cancel off the rotating effect.

If u look at Cypher design, it is actually consist of 2 propeller spinning in opposite each other.

If not, they u really need a flap at the bottom and the flap must be big to counteract it.... just like those 3D profile airplane.

Super-Hornet

hi super hornet,

the 4 pairs of flaps at the bottom are to balance the spinnig torque. that's what i'm trying archievefin this project. you mentioned about the control surface, how to find out the relationship between the control surface and the balancing? some ppl said this is kind of 'mission impossible' to balance the couter torque simply by using the flaps, but theoretically it's feasible.......the problem is just how to archieve it. currently with my control algorithm, i'm quite confident that it can work, however, i'm not very sure about the mechanical design which might burden the control scheme.

like what TELE said, i wish to put the battery below the fuselage to give the centre balance, but i'm not very sure about how to choose a suitable battery......could you please advice on this?

[Super-Hornet]

OK...

Using flap to counteract the rotation is possible... Just like those 3D plane. One thing for sure is that u need total wide surface area to have sufficient air flow to counteract it. How much surface area... not sure.

Your tilting or sliding at one side could be due to:
Your propeller too high and between the propeller and the doughnut is not shielded. What u need is like thos ducted fan design where the airflow from propeller is guided straight downward without any air flow leakage.

Using flap to counteract the rotation is possible but it is going to be difficult. Ask those 3D airplane flyer on how does it feel when doing hovering. Is it difficult?

Easier way would be using counter-rotation blades.

[ccwee]

Originally posted by Super-Hornet
OK...

Using flap to counteract the rotation is possible... Just like those 3D plane. One thing for sure is that u need total wide surface area to have sufficient air flow to counteract it. How much surface area... not sure.

Your tilting or sliding at one side could be due to:
Your propeller too high and between the propeller and the doughnut is not shielded. What u need is like thos ducted fan design where the airflow from propeller is guided straight downward without any air flow leakage.

Using flap to counteract the rotation is possible but it is going to be difficult. Ask those 3D airplane flyer on how does it feel when doing hovering. Is it difficult?

Easier way would be using counter-rotation blades.

wow, super hornet, thanks for your prompt reply~~~ help me alot~~ ^_^

so, i actually have thought about duct the air flow, but my properller seems to be too long.....i not sure about how to choose a suitable propeller.....somebody told me that for hovering only, low pitch and long propeller is needed....is that true? i can't find any info about matching of propeller with my Hacker B40 motor, i have tried a 1080x4 propeller, it simply can't lift it up......headache....

one more thing is the battery......below are the spec of the
controller and motor

controller: 40A, 6-12/4 cells, 10cells for 4 servo, 8 cells for 5 servo
motor: 15 to 35 amps, good in 7.2V to 19.2V

does this mean 10 cells is good enuogh for my flying craft? how much voltage can 10 cells provide? what battery you normally refering to when you talk about 'cell'? LiPo? NiCd? or else? what does it mean by mAh? how to interprete the mAh value?

thanks again for your help, have a niceday~~~