RC India

Hey guys , I started construction of a TopFlite School Master from plans. Using Japonica as a substitute for balsa.

I posted a build log on RCUniverse

http://www.rcuniverse.com/forum/scratch-building-aircraft-design-3d-cad-174/11584836-top-flite-schoolmaster-scratch-build-log.html

Pls. Do comment on how it has turned out so far.

N.B. The plane is made completely from Japonica(Dhupi Pine)
Regards

Yashodhan Pasari

Why didn't you post your build log here? I don't want to go to RCU specially to see your build.

Ok shall post it here no issues

Great  :thumbsup:

Look forward to viewing this build  :thumbsup:

Hey guys, i started work on a Top Flite SchoolMaster. I decided to use only Japonica aka Japanese Cedar because of its low cost on ready availability in here.
Japonica is around 1.5 - 2 times heavier than balsa and slightly brittle.
It can be cut using a 'Box Cutter' or a fine tooth 'Hack Saw'.( Hobby Knife NOT recommended)
I spent around INR 500 on the wood for the entire model.

I made a few modifications to the actual plans:
1. D - Tube Construction instead of a Fully Sheeted wing
2. Addition of two Spars to the ribs to impart a bit more strength.
3. Conversion to electric
4. Using solid Japonica for the Horizontal Stabilizer instead of a sheeted construction.

Fuselage:

Started of by sticking additional strips of japonica to the main sheets to get the correct width of the fuselage.

(http://www.rcuniverse.com/forum/attachment.php?attachmentid=1907195&d=1376320323)

Rough cut the fuselage sides using a hacksaw for sanding into shape  ;D

(http://www.rcuniverse.com/forum/attachment.php?attachmentid=1907196&d=1376320343)

Added a template cut from plans to the pinned together sides for final sanding of the Fuse sides

(http://www.rcuniverse.com/forum/attachment.php?attachmentid=1907198&d=1376320367)

Final result after sanding.

(http://www.rcuniverse.com/forum/attachment.php?attachmentid=1907200&d=1376320449)

Sorry no pictures of the actual fuselage build. Was too engrossed in building the fuselage and forgot about pictures.  :( ??? :banghead:


Applying top and bottom sheeting (Had to apply Elastic Bands to hold the sheets in place due to the low flexibility of Japonica

(http://www.rcuniverse.com/forum/attachment.php?attachmentid=1907201&d=1376320494)
(http://www.rcuniverse.com/forum/attachment.php?attachmentid=1907202&d=1376320499)
(http://www.rcuniverse.com/forum/attachment.php?attachmentid=1907203&d=1376320504)

Final pics of the fuselage (Currently fit with an E Max 2215/09 Motor with 10 x 4.7 Prop)

(http://www.rcuniverse.com/forum/attachment.php?attachmentid=1907206&d=1376320581)


Wing:-

The Wing was where the most number of changes were made because it was fully sheeted,which I converted to a D Tube style construction and added spars.


Basic Assembly (Sorry for poor quality of pics)

(http://www.rcuniverse.com/forum/attachment.php?attachmentid=1907208&d=1376320725)
(http://www.rcuniverse.com/forum/attachment.php?attachmentid=1907209&d=1376320754)

After Application of the Sheeting and Cap Strips

(http://www.rcuniverse.com/forum/attachment.php?attachmentid=1907210&d=1376320804)
(http://www.rcuniverse.com/forum/attachment.php?attachmentid=1907211&d=1376320811)


I shall be using 4mm Carbon Fiber tubes Epoxied into place as the wing joiners
Covering of the model shall be done using BOPP Film that is adhered onto the wood using contact adhesive and shrunk using a normal household iron.Will paint over it using Enamel Paints to a Nice Colour Scheme after the first test flight.


Horizontal and Vertical Stabilizers and wing joining an covering shall be posted by the end of the day, only clicking of pictures os left

Pls. feel free to comment on the Model, and how the build is coming along. I am open to suggestion, criticism etc.

It sure looks wonderful!  {:)} {:)}

1. What are the model specs i.e. Wingspan, Overall length, wing chord and area, and expected All Up Weight

2. The plans: could you post them, or a link to them  ;D

Wingspan is 39"
Chord is 7.5 Inches
Weight: not really sure yet,
fuse length :29 Inches or so
originally designed as 1 Channel (Rudder) with a Cox 049

I've made it 3 Channel and electric.

will post the plans by end of day today

How did you get the sheets? What are the dimension, cost, availability etc.... do spend time on these as sourcing materials for builds can be problematic.

There is a local source for Japonica., there are no fixed prices or dimensions, sheets will vary from thickness to thickness. Sheets cost 35 on average. Its known as "Dhupi Pine" locally

Good effort using Japonica.
Pl post all up weight when complete. If not too heavy, we can also follow your lead.
Used to be a kit from IHC called Schoolboy or Schoolmaster.
Schoolboy 36" Ken Willard plan available for free download at outerzone.co.uk

Thank you sir..The school master is also by the same gentleman. There is a larger kit known as the HeadMaster as well (48" span) and a School Girl (Bipe) both designer by him.

I have been using my cell phone or tablet since the start of the post so havent been able to upload the plans for the same. Will upload plans at night. 100 %

Still,for the sheets you are using, what are the approx dimensions - especially the sheet thickness

On average sheets were around 37" long and 2 3/4" wide, and nearly 1..7mm thick. Rule of thumb is to sand the sheets a to not just achieve smoothness but also more or less identical thickness. (lay them side by side, sand the thicker sheets first, then sand all of them together 2-3 sheets at a time). Japonica is a lot more forgiving than balsa when it comes to cutting it because its a bit hard. And it has a number of extremely hard knots here and there, so one has to be patient to get through those (fine tooth hacksaw works the best), also its a lot more brittle than balsa so cannot be bent to much.

I used a steam iron with the steam on MAX to bend cap strips for the upper surface of the wing. Then used rubber bands to hold it in shape)

And yes I forgot, one can use CA liberally. Because of the woods hardness, u can sand those areas smooth without gouging a surrounding area as is with balsa.

As for the plans

http://www.rcgroups.com/forums/showthread.php?t=749222

I downloaded them from here (Tiled and stuck them using GLUE STICK since it's a lot better than cello tape.) You should print out two copies of smaster A-E ( one as template other for construction)

AUW including all electronics is  730 gms. around a 120 gms. heavier than the weight recommended for balsa. Fairly good IMO.
I would like the more experienced builders to comment on the weight of the model.

Maiden will be done this sunday.

post a pic of the completed model .

weight is on the heavier side but should not be an issue
if you built straight and put in adequate downthrust.

keep the speed up on maiden .

will do so by tomorrow. i gave it two washers on each screw to give it down thrust.

@Yashodhanp
Not enough info in your pm to comment.
I gather that it is 39"span 7.5" chord, 2 sqft area, 730 gms.
In effect 12.5 oz/sqft.
It wont be difficult to fly as the wing cubic loading is under 9.
But you did not say which motor, prop and battery.

motor : emax gt2215/09
prop : 10 x 4.7
battery :  3S 2200mah

@yashodhanp,
Power will be more than enough. May not need over half throttle.
My estimate is 25kmph stall speed, 70kmph level top speed.
You could later try a smaller motor.
She will fly, as long as (like Saikat says) you built it straight.
Best of luck.

Yup, it is fairly overpowered. Will fly at half throttle or less

Maidened it this sunday, Good flier ,but a few modifications will need to be made. video coming soon.


 It Needs a smaller power system the current one is consuming a LOT of power and giving poor flight times. And also landing gear will be changed to a wire type to absorb more shock.

Dear friend,
I would advice you to use a diagonal grain sheet for the top and bottom sheeting of the fuselage.  Use them on one side on the top and the cross diagonal at the bottom.  This gives more rigidity to the fuselage structure. 
Best wishes

Can you please tell me where can I buy Japonica.... have been looking for it for long.  Its ideal for making covering sheets and spars... long ago Arora models of Calcutta (Kolkatta) used it for all their models).
Regards
Shobhit 09455380339