1/6 Piper Cub (Svenson) in Corro

Started by sanjayrai55, March 21, 2016, 08:49:37 PM

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sanjayrai55

#50
Supports for the hinges on the struts


Tanmay.mathur

Sir how do pipers handle in the wind?
Regards,
Tanmay mathur

sanjayrai55

Nothing much to do with Pipers. More on weight, size etc. of model

However, the few I have seen flying (models, not full size) did seem to have a tip-stall tendency

Tanmay.mathur

So which do you prefer for beginner- oshkosh trainer or piper. Both as 4ch.
Regards,
Tanmay mathur

Tanmay.mathur

Regards,
Tanmay mathur

sanjayrai55


sanjayrai55

#56

flyingboxcar

I see you have apprehensions about strength of the wing with that 12mm balsa spar. The best way (in terms of weight addition etc) to overcome the situation is to use functional wing struts. Those would not only look scale but also serve to provide you the required strength. Make the struts out of suitable dia wire and clad them with balsa. You can solder on metal plates at the end with suitable hole through which you can screw/bolt the struts to fuse and wing hard points  
If you are really into scale you should be here. www.rcscalebuilder.com

sanjayrai55

I am making them :D

Part of the plans, and were in fact the first materials I checked before starting. I will be using 8 mm Aluminium Tubing

But, I still have apprehensions  :D :D.

And Captain, thanks so much for the support  :thumbsup:

sanjayrai55

#59
Actually post # 50 mentions it

And, in continuation:



Hinges for the wing Struts:


sanjayrai55

#60
Hinges fitted into the balsa block already glued in. The wire strut support will fit into the ply piece already glued in the wing inner


sanjayrai55

#61
Closing up the wing


sanjayrai55

#62
Wing completed




sanjayrai55


sanjayrai55

#64
Checking wing incidence and likely CoG position




K K Iyer

Sir,
I fear that this thread may convert me into a Coro builder!
Please share expected wing loading and proposed power.
Did you consider spar made of 'baten'? (As in Windows), instead of balsa?
Regards

sanjayrai55

#66
Iyer sir, never fear. Convert  :D :D

Here are the specs from post # 1


sanjayrai55

As per the designer, weight is 1700 gms + RC equipment, ie 4 standard servos + Rx Battery, Rx, wires etc. Say 300 gm approx giving a total weight of 2 Kg

Wing Area is 46.4 dm2

So a wing loading of about 43 g/dm2

In the write up, the designer recommends a 19 to 25. I'm not so interested in speed. So I'm using a Turnigy G 15 - 950 KV with a 12*6

RC Tools shows:

12*6
30 deg. C
9000 rpm
Static Thrust 2.01 Kg
453 Watts
Flying Speed 51 mph (about 80 KmPH)

Which should be OK.

The motor specs:

Spec.
Battery: 3~4 Cell /11.1~14.8V
RPM: 950kv
Max current: 34A
No load current: 10V/2.0A
Current capacity: 42A/15sec
Internal resistance: 0.03 ohm
Weight: 152g  (not including connectors)
Diameter of shaft: 5mm
Dimensions: 73x35mm

Required;
45A ESC
3S~4S Li-Po / 8 ~ 12-cell Ni-MH/Ni-Cd
10x6 ~ 13x6.5 prop



Although it says max current 34 A, a 13 X 6.5 Prop will draw over 50 A at full throttle. So I'm going with this

In normal cruising, with a weight of 4.4 lbs, I do not think the wattage will exceed 250-280 W

I am most interested in hearing your views!

asinghatiya

 :o THIS IS beautiful sir!

Wait for me, will do its maiden  ;D
:-)

sanjayrai55

Thanks Arvind. Waiting.............. :giggle: :giggle:

rastsaurabh

It will be good get-together again.

sanjayrai55

We all wish so Saurabh. But Bangalore to Gurgaon is indeed further than Noida to Gurgaon  :) ;) ;)

prabal276

When will this bird fly?
Regards
P.s - excellent build sir!

sanjayrai55

It will take another week to 10 days to get ready I figure

sanjayrai55

Been reading more about the dreaded tip-stall

Seems quite common with Piper Cubs!

The flat bottomed wing means on power there is a tendency to climb (ballon). On aileron turns, at lower speed, the inner wing half will turn slower than the outer. So the outer will tend to rise... progressively....and lead to a spin  >:D

Seen it happen to some of the better fliers on our field too, and yes, on the Piper Cub  >:D >:D

Well, I'm not that good a flier, so this is what I'm planning:

1. Turns will be rudder-aileron co-ordinated - start with rudder eg left rudder for a left turn, add a little left aileron to complete the turn, release rudder, right aileron to level wings
2. Will put about 3-4 mm aileron reflex. Barn door ailerons only about 1/3 of the span, hope it will act as washout
3. For landing, will have to "fly it in"under power
4. Will use 2:1 differential aileron

Would appreciate suggestions from the seniors on this