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my first foam rc model

Started by bpbeni77, July 24, 2011, 02:21:23 PM

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bpbeni77

hi guys
i'm new to this so please excuse any mistakes i make.
Well i thought i'd post a few pics of the model. its not there yet but i think i'll be dome in a couple of days. Its made out of styrofoam and i've ordered the Flysky 9ch , 13" prop and a 3548 brushless with a 2200 4 cell. i'm wondering how to distribute the load from the motor mounts and the landing gear??
Please suggest improvements that i would be able to make too.

beni

bpbeni77

here are a couple more pics

bpbeni77

and the wings....
2200mm wingspan

roopeshkrishna

Beni...its a nice effort...i could see one thing..that all of the scratch build aeroplane is a flat faced one...!!!  may be due to the ease of construction,but we can make it in to a radial shape by just papering it...it can reduce the drag to some extent, and also gives a nice look to aircraft...its easy to fix a motor mount and landing gear to a model...first of all cut a piece of 4 mm balsa or 4 mm foam board (sun board),and place on the nose of the aircraft.mark inside the sheet with a marker pen.cut this shape with caution..after finish it's edge with 320 or 400 grit emery paper...then slice two more strips from same material, that you used, as in to a 2 to 3 inches long,and 1 inch wide.stick these pieces just inside the previously cut piece, and let to dry..after drying, fix the base of your brushless motor, or brushed motor, on to motor, and fix it on the face plate that we made..mark all four holes with marker..drill it...now you can buy some whine nuts or ordinary nuts with a flange to the size of the hole, and fix it with motor ...then drop some super glue, or epoxy only up to the lip of the nuts...let it dry..when dry remove the screws from flange and remove the motor...now time to fix on aircraft...make two cuts deep in to the fuselage up the strips that we fixed to the back side of the flange..apply some appropriate glue to the strips and insert in to the fuselage from nose to tail...apply little more glue just prior to the flange reaches the fuselage...

let it dry...
after drying you can fix your motor on it...its easy to fix a motor if you take care some care just before making the fuselage...a long strip of wood, reaching up to the tail from nose placed within the fuselage can hold the motor, tail plane and rudder...and yes the main wing...

cut out a small piece of balsa or scrap wood ( tomato box is ideal). take two thin bicycle spokes and shape it according to your need...fix two toy car wheel at the tips..jam it by some silicon tube..drill two hole to the wooden piece and insert the spokes in to them..apply little epoxy glue..and make a cutting just underside of the fuse lage and insert the wooden block in it by adding some glue...you can also reinforce its strut with fishing lines...
Phoenix.........

roopeshkrishna

there are many simple way to get a smooth finish over the styro and thermocol...then the aircraft will be smooth and good looking...

and i hope your power setup is too inappropriate...a 13 inch prop...ohhh...
Phoenix.........

bpbeni77

thanks a ton for the reply...a few questions..
how can i get a smooth finish on the aircraft? you had mentioned papering..does that mean sticking thin sheets of paper over the aicraft with fevicol?? how do prevent the paper from wrinkles? does the foam warp when you apply so much fevicol? any other ways to get a smooth finish?

i'll build the mounts like you said and put up a few pics. Should the wings be permanently attatched? or removable and if it is attatched how and where do i place the recievers and servos?

roopeshkrishna

Beni...when we make an aircraft from a kit, there must be all pre cut materials and instructions..but when we makes a craft from the scratch, we can choose our options..it may be anything that appropriate and worthy..there is no any restricted way to make an airplane or a boat or a car, if you are making from scratch..but make sure that all used materials are worthy for the purpose..flying an rc plane is just like learning to ride a bicycle..when we get the logic of flight..you can take any machine in air..but make sure our craft is under flight characteristics..and CG balanced..

fixing a wing permanently is not a good idea unless you make an option to access inside.we can fix the servos at tail tips but never forget that we have to add some counter weight to overcome CG balance..additional weight..?  bad flight characteristics...so fix the whole servos as near as possible to nose, and do not use any heavy metallic rods to link it..instead we can use a good quality thick fishing line to connect the control surface in bi-mode.so you will get a nice crispier response without any loose effects, even at loads..
Phoenix.........

roopeshkrishna

we can get a nice flight from our crafts by changing the angle of attack of the main wings..for that we can add a thin piece of foam or thermocol just under the wing at leading edge..a simple trial and error method can prove a best setup to the aircrafts.and can be use two or four nylon bolts and nuts instead of rubber bands from bottom to wings..some attachments with thin balsa sheet will hold the wing nicely in place..and remember..a slow flying aircraft is not meant for aerobatics..a fast maneuver from a light airctaft can break it in to pieces...
Phoenix.........

bpbeni77

thanks roopesh
i think i get the picture. I tried papering the aircraft with thin paper but the sheet wrinkles and doesn't form a smooth covering. I'll try something else.
I'll keep the cg and cp in mind and balance the whole thing before test flight.
i'll keep all the electronics under the wing and ahead of it.

hope i get a good finish

bpbeni77

i'll try and make an attachment to the wings from the two reinforcements running through the fuselage

Swapnil

@ bpbeni77:
Hey! Good start. If by '3548 brushless' you mean  Aeolian C3548 (790 kv) then a 13 in. prop is a good choice. I hope it's the recommended 13*7.

Swapnil

For getting a smooth finish, try brown packing tape. It is much lighter and smoother than paper.

bpbeni77

@swapnil
Thanks buddy , i'll try that out. I'm right now in manipur and i need to work with limited resouces....will try my best to find some brown tape around here.

Swapnil

#13
Packing tape is easily available in any hardware shop.

I can't see any dimensions in the 'plan' pic. Could you post details like lengths of chord (even nose and tail if possible), dihedral angle, target wing-loading etc.
In reply no. 2, you state the wingspan as 2200 mm. That's around 7.2 feet. If this is your first build, maybe the power setup is bigger than recommended to start with.

bpbeni77

i've built foam free flight gliders before. Its the first time installing an rc system though....

roopeshkrishna

Beni...have a nice flight...
Phoenix.........

bpbeni77

dimensions...
2200mm wingspan 5degree dihedral (40mm of each wing tip)
1400mm fuselage length.
chord 400mm approx at base
        300mm approx at 800mm on either side from base
high wing design with a puller prop sys.
will mount motor in the front.
tailplane...horizontal stabilizers 250mm chord length and 900mm span
rudder heigth 200mm
         base width 250mm
         width at tip 100mm

bpbeni77

thanks roopesh for all the advice..will keep you guys posted

Swapnil

Oh, good!
I was just trying to say that for a 1st electric powered plane maybe the plane size and power-setup are a bit large.

bpbeni77

wanted to make an FPV setup ....really long range on the same airframe. did'nt want the load carrying capacity to be too less.

Swapnil


bpbeni77

hey guys the papering is working!!! it looks much neater and i'm sure it'll aid aerodynamics too

sundaram

Hey beni Great going there. 2200 mm!!! Make it Large you have taken that seriously.  {:)} {:)}

For 2200 mm You have to seriously think about reinforcement as the load on the wings are going to be huge and especially for a Styrofoam.  Zonuna from Aizwal has been successfully making Styrofoam planes by just reinforcing them with bamboo, and skin with paper and fevicol and has been flying with glow engine on them.

For a cutting aerofoil on styrofoam people have been using hotwire bow.

The one we flew in Jhansi the aerofoil was purely sanded to shape with an electric orbital sander with finest grit paper.

After you give aerofoil shape to the foam now for the reinforcement part cut two to three 3-5 mm deep straight grove with Xacto blade on both top and bottom surface of the wing, in which you can insert thin bamboo strips/ carbon strip/ 1mm Glass rod/ even stiff fiber optic wires which can be salvaged from scrap fibre optic cable left behind by mobile and telcom guys.

Now since you may not be having a foam safe CA apply araldite or fevicol into the grove before you insert the reinforcement.

After you insert the reinforcements now you will have to protect the surface from damage by either using packing tape/ wider cello tape/ Easy tear paper tape or like zonuna can use fevicol and paper or thin layer of araldite and thin fabric. However when using paper in fevicol and Araldite with fabric you must watch the quantity as both adds up to the weight a lot. For that mater packing tape is the best bet since packing tape can be smoothened   by using iron on low heat or hot air gun/ hair dryer. It give a shiny smooth surface.

roopeshkrishna

Sundaram Sir..thanks for the guidance...
Phoenix.........

bpbeni77

updates on my model...