Hi RC Enthusiasts,

Till date I was interested in scratch building of Depron and Thermocol (EPS) based RC Planes and was enjoying the Hobby. Of late I tried to introduce the hobby to my son who is eight years old. I first exposed him to the skill of flying through FMS simulator and Clear View simulator. Once I was confident that he has picked up flying skill sufficiently to fly a real model. I took him to the field and with my two 2.4 Ghz Futaba 7C and Futaba 6EX linked up with Futaba WTR-7 wireless buddy trainer system, I exposed him to flying. He is picking up fast. and he was enjoying flying with me and we venture out every sunday.

However since he is small and is not comfortable to the glare of the sky, inspite of a sun goggle and since the Models are all fast and highly responsive he was compelling me to build him a small slow flying model which he could fly indoor or in a house lawn. Inspired by http://www.youtube.com/user/tyoukogatalabo I took to Micro and ultralight flying also appart from my regular flying.

I am posting photographs of the model, which I have been very successfull and really happy with. Any one in the Forum who is into Micro RC please post your designs and achivements please. I see very little of Micro RC in the forum

Wow ! 

The closest I ever came on micro planes (I should not call this "close") is with a Kyosho Minium RTF.  When the fuse is dead, we (my brother and I) do plan to put the electronics into something built out of styrofoam plates or something like that, but nothing in the near future !

Thats a nice foam plate cut to the wing pattern. Can it take micro 3gm servos that Sai has @ RCForAll???

I've got exactly the same type of foam plates with me and built myself a foamy with abutting segments cut out of multiple foam plates. Built a bit heavy and am having to rebuild the fuse.

But this one looks cool with a neat polyhedral built in.

Any videos of this will be great.

Pls. let know of the feasibility of using 3gm servos for this type of plane.

Quote from: tg on January 07, 2010, 06:01:19 PM
Any videos of this will be great.

Pls. let know of the feasibility of using 3gm servos for this type of plane.

Specification of the Model are
Wing (Biofoam/Depron Plate) Span less the Poly hedral is only 10 inches.
Brushed 7mm motor 2.9 gms
Three channel 900Mhz receiver of Plantraco 0.9 gms
Home fabricated acctuators two numbers for elevator and rudder 1.1 gms
Bty 90mah 3.7V 3.0 gms
Propellor 2510 GWS.
Total weight 11.8 gms

It is not likely to take a 3 gms servo with the present configuration. Wing Span at 15 - 16 inches may take a 3 gms servo

Before painting the model, me and my son had done lot of flying but did not record it. After the day I have painted the model it has been very windy here and I am not able to fly it. On next oppertunity of flying I will record it and post it.

I am experimenting with a similar plane around 60 gms  but  with a difference I am looking at using a  discarded servo's motor  with the POT directly connected to aileron channel  to spin a prop ( inspiration from helis tail rotor ) ,
Works well on ground  as this motor spins the prop in both directions .

No Moving surfaces at all on this plane .

Should try it out  in air in a few days time .

Sai

Mr Sai,

That is a very very good Idea. does the circuit board inside the servo which controls the motor inside servo also controls the speed of the motor. In other words can the circuit be used as speed control for the motor apart from reversing the direction?

I had seen a similar design in http://www.youtube.com/user/tyoukogatalabo, where a micro flying wing was flying with two pusher motor whose speed control was put through elevon mixing and turning of the flying wing was by altering the speed difference between the motors and elevation was controled by increasing and decreasing the speed of both the pusher motors. The flying wing did not have any moving surfaces. If the servo circuit can control speed this can be very easily achived without the requirement of ESC.

Please post the photographs of your design once completed.

Hello everyone,

I am posting the vedio of the Micro flight here

Nice 

The flying field looks cool too, where is this ? 

Flying field is a Old Garrison Bunglow of the erstwhile British Raj,
presently our Unit Officers Mess at Jhansi.

Quote from: sundaramvelar on January 09, 2010, 06:49:35 PM
Mr Sai,

That is a very very good Idea. does the circuit board inside the servo which controls the motor inside servo also controls the speed of the motor. In other words can the circuit be used as speed control for the motor apart from reversing the direction?

I tried it out it works fine but the plane is a bit  difficult to control as the direction of air flow  does not reverse immediately like a servo   and the flow in one direction  is stronger than the other  so I made  a 100 gms out door 3 channel coro micro with 3.7 gms servos for the time being  .

But not given up on the idea  of a junked servo's motor  I think this will involve   some amount of thinking to put to practical use .

I was thinking  the variation could be used  to counter the torque roll  by having the stronger airflow opposing the TR and the  weaker  direction for turning in the direction of the TR , concept seems workable  but practical might be a different story

Sai

Mr Sai,

I think reversing of propellers may not be required to turn the plane. Only increasing and decreasing speed of the (counter rotating may require a counter rotating porps) propellers of one side inrespect to the other may be sufficient to turn the plane and simultaneously increasing and decreasing the speed of both the motors will provide required lift / fall in lift to control elevation. This can be achived by both the servo motors connected to alieron channel and elevator channel in elevon mixing mode.

"Now only problem is ESC for both the motors". If the knob of the POT in the servo is kept in the center of full traverse the servo motors will be idle in center stick and will turn in both direction with the stick movement on either direction.

Alternatively if the knob of the POT in the servo is kept turned to one direction. Then the motor will come to idle only when the stick is deflected to the coresponding direction fully. And when the stick is turned to the other direction the motor will now turn in only one direction.

However my question still remains. Weather the circuit inside the servo controls the speed of the servo motor corresponding to the amplitude of deflection of the stick? I need to try this to get an answer for myself.

However I think if the servo motors are connected through two of the 3 Amps 3.7 Volts Micro JST Micro ESC in ebay rcforallin shop in the alieron and elevator channel in elevon mixing mode will do the Job.  

Quote from: sundaramvelar on January 19, 2010, 10:06:26 PM
Mr Sai,


"Now only problem is ESC for both the motors". If the knob of the POT in the servo is kept in the center of full traverse the servo motors will be idle in center stick and will turn in both direction with the stick movement on either direction.

However my question still remains. Weather the circuit inside the servo controls the speed of the servo motor corresponding to the amplitude of deflection of the stick? I need to try this to get an answer for myself.

I have tried it out and it works perfect  with a centered POT  the direction of the prop rotation  is reversed  when  the stick is moved  left/right of the center . In  fact I thought of this idea  quite by accident , I had a  broken servo , I recovered the motor from it  thinking I might use it some time later  , saw one of the MODEL ART helis in a shop and found a motor stuck into the tail for pitch control . This got me thinking on using the motor , around the same time Nandakumar also told  me he had used a motor on his 20 g plane .
So put 2 + 2 and thought why not try.
The speed of prop rotation is also proportional  to the movement of the stick it works  fine  but the issue I have come across in this application is the prop pitch being fixed the air flow  is not the same in both directions . So control is a difficult , that is why the idea of using the weaker airflow with the torque roll  .

Will try it some time.
Sai

Mr sai,

I am inspired by the idea. Now i am also motivated to tryout such a design for a micro plane under 20 gms preferably a flying wing, Komet or a B20. I have two to three of defective gear servos from where I can recover the circuit and the motor even the gears can be used for turning a bigger prop for more slow flight.

I am looking at propeller rotation unidirectional only.

Are there any counter rotating propellers available under 3.5 inches? I have to search out.

Presently I am busy with converting electronics of the cheap two channel IR helicopter crashed to be used in a plane frame in a twin rotor pusher/puller configuration in a similar design. Only the two motors I am in search of since the motors of the heli are of different sizes. Will post design and concept if successfull.

Mr Sai,

I am posting photographs of the micro which I have constructed using a two channel IR heli circuit.

Specs
IR Transmitter of cheap Rs 700/- worth IR heli with tail rotor.
Receiver IR Receiver two channel one for main rotor motor and other for tail rotor motor. Battery 75Mah 3.7 V Lipo. Weight of receiver along with Lipo 3.2 gms
Twin pusher prop mounted on two 4 mm coreless motor connected to both the channel of the IR receiver. Two 4 mm coreless motor with the prop 2 gms approx.
(NO CONTROL SURFACES)
Total weight of the micro model is only 12.16 gms.

Both the channel motor speed is controlled by channel one (The throttle). Channel two controls the speed difference between the two motors (turning of the Heli is achieved by the turning of the tail by the speed change in the counter balancing of the tail rotor).

Intended method of flying in twin pusher configuration was by control of elevator by throttle control (Channel One) of both motor and turning control (Channel Two) by speed difference between the two pusher motors.

In Simple Chuck glider mode with all electronic but not switched on it glides very well.

However not satisfied with flight in the powered mode. In straight flight it glides very well but turning moment provided by the speed difference is not much, it turns slowly. Problem starts when it starts to turn in a direction. It is not able to recover from the banking roll in the direction inspite of input for other direction and it slowly spirals into a decent and lands.

My inference is in-sufficient dihedral for auto stabilisation. Any other improvement/ suggestions please?

Ok now my inference on the lack of dihedral was partially correct as since after providing sufficient dihedral the micro is gliding like a bird.

My other problem of lack of sufficient Yaw turning moment provided by the difference in speed of two pusher propellers is still prevalent. Closest circular loop possible by the micro is 16 Mtrs in dia. Because of such large dia of circle of turning though it looks very pretty, due to lack of sufficient range of the cheap IR Tx, the micro very easily goes out of range when you try to change and turn in opposite direction.

However the sound of the twin pusher propellers which is mounted in the middle of the 1 mm depron wing is accentuated and very beautiful. It is sounding like an actual plane.

I thing I will have to open the Tx and try some tinkering with electronics to see if the range of speed difference between the two pushers can be increased.

Before trying any thing with Tx I am going to paint the micro and record a good video and post.

More pics and video are on the way. Any suggestions and improvements by any one most welcome please.

nice plane looking forward for the video   

Here in Jhansi there was a sudden change in weather and there was sudden shower with thunder storm and hail storm. So no luck with flying so posting some preflight vedio and painted photographs

Very Nice Sir looks great , my focus is an out  door  micro in Coro so I am not going to get it too light , but I just got a GWS radio where the receiver is just 3 gms in weight :
http://cgi.ebay.in/ws/eBayISAPI.dll?ViewItem&item=110490963157#ht_1290wt_939

This 2.4 G radio is really good  and beats the IR radios any day.
Sai

Sundaramvelar, very nice build, as usual. I saw the video, she sounds great too.

Regarding your turning radius, I had a thought. I have a Chinese made 2 Ch twin pusher plane, which  uses the same principle for controls. One channel controls the on/off function for both motors. Port engine on / Starboard off = Aircraft turns to Port and vice versa. It has no other control surfaces. Exactly the same principle that you are using.

However, you will notice that the 2 engines are mounted close to the fuselage and not out on the wings. Also the engines are not parallel to the fuselage, but are mounted at an angle of 20 degrees out. Thus, when the props spin in unison, they cancel out each others torque / induced turn. When only one works, it provides a greater vectored thrust on the airframe.

Will these factors ensure a change in the turning radius on your little beauty?

Just a thought, as I mentioned earlier.

Cheers!

VC

I have EXACTLY the same plane (Blue) I bought form 2400 in 2006. I flew it only one day with two crashes. Mind you there is NO proportional thrust. One motor would 'Dead Stop' moment move the stick. The banking comes at the cost of nosedive if you don't adjust the Throttle (the only prop ch) right.

I am currently working on converting the Plane with Ailerons/Elevator and a single pusher brushless. Had a failed nosedive takeoff maiden which broke the Vineer motor mount.

Quote from: VC on February 10, 2010, 10:13:21 AM
Also the engines are not parallel to the fuselage, but are mounted at an angle of 20 degrees out. Thus, when the props spin in unison, they cancel out each others torque / induced turn.

Thanks for the compliment.

I think mounting the pusher at an angle outwards will surely increase the turning radius. I will surely try out this thanks Mr VC

Here is the video of the micro.

The range of the tx is still a major issue. It becomes non responsive once out of range. Turning radius was improved with Mr VC advice thanks. Although it flies for more than five min at a stretch, the initial vigour is lost after four loops, which is fast and it climbs rapidly (I could not record when it went into tall tree and was removed after lot of jumping and pulling branches). After a min of flight it is between half throttle and full throttle. Last part of video it hit the wall and fuse balsa broke into two.

Altogether a good attempt for a Rs 650 IR electronics. After repairing it I will be giving it to the exited kid in the video who is my neighbour and friend of my son has been troubling me for a remote plane.

Air frame was a major success but the IR Tx and Rx is still doubtfull if range is not increased.

I will continue using my 900Mhz Plantraco Tx and Rx which has good range for a micro for a similar air frame.

"After repairing it I will be giving it to the exited kid in the video who is my neighbour and friend of my son"

Lucky fella, who will destroy this work of art in 5 minutes flat. You have a big heart Colonel!

yupss,u really have a big heart!!
well to my knowledge the range of the IR tx & rx could be increased with few minor tricks
[http://www.rcgroups.com/forums/showthread.php?t=74227
&
http://www.rc-cam.com/microszr.htm]
i think using more power full batteries would help in that case[duracell 9v alkaline works gr8 for that purpose for both tx and rx]
if urs have a antenna[if i m right ,IR don't have but fm/am have] using a longer antenna would also help