Hi friends i want to know thrust of ASP S21A becuses my plane weight is about 1200gms 

The suggested prop is 8*6
The max rpm is 19000, but that would be under ideal conditions, with a high nitromethane percentage

Assume 14000 rpm

For an 8*6 that means:

Static Thrust: 0.96 Kg
Power: 337 W
Estimated Flying Speed: 128 Kmph

This will be adequate for your 1200 gram model, if it is a trainer, or sports model. If it is for extreme aerobatics or 3D it is not enough

Same doubt, my plane is weighing 1000g without powering system(battery, motor and esc) rest all including servos. Weight is approx 1000g which engine should I go with .?
By amount the plane weight will increase if I install engine tank extra engine servo .?

What is the model size, and type? As an advanced flier this is a strange question coming from you

sanjay sir, he wants to know, can this engine be 'trust'ed if you look carefully

it would be great if i get my answer...

I'm new to Nitro planes always have used electric planes.. switching from electric to nitro engines.

Repeat:

What is the model size, and type?

As an advanced flyer, whether electric or nitro,you know it is of less importance than the type of model in power unit selection

Gusty Saheb, I wonder if he "trusts" us 

Question 1 more time, it will be great if some1 reply properly
"Same doubt, my plane is weighing 1000g without powering system(battery, motor and esc) rest all including servos. Weight is approx 1000g which engine should I go with .?
By amount the plane weight will increase if I install engine tank extra engine servo .? "

"Advanced" yup i'm advanced. My hobby is Nitro car not plane though i fly planes but only electric. Going now to nitro.  
I'm a car lover  please read my profile before commenting 

There can be no complete answer with the data you have provided, which is incomplete

If you were electric, which power system would you use? It could weigh 200 grams to 600 grams for a 1 Kg model. eg, a glider would need 200 W and you could manage in 200 grams (Motor, Battery, ESC) A 3D model would need a motor with a thrust of over 1.5 Kg, weighing about 150 grams, ESC about 75 grams, and battery for 10 minute flight about 300 grams.

Similarly, you could select an engine from a 0.10 (about 300 grams) to a 40 (about 600 grams)

Therefore provide full specs of your model along with photos for any meaningful sort of reply. If you give incomplete information after 2 reminders it is weird to say that you are not getting a reply

Overall weight excluding battery motor and esc: weight 990g.
wing: 1442 mm

You have not mentioned the type of model 

Assume it is a high winger trainer:

The approximate weight with a motor/battery/esc set-up will be 1.3 - 1.4 kg

If I use a 10*6 prop, and a Motor KV of about 1000, I get :

At 9000 RPM,
Static Thrust (on the ground) 0.97 Kg
Required Engine Power: 219 W
Est. Flying Speed: 82 Kmph

So, let's see what we can get for this:

Look at http://www.hobbyking.com/hobbyking/store/__18228__Turnigy_D3536_8_1000KV_Brushless_Outrunner_Motor.html

Turnigy D3536/8 1000KV Brushless Outrunner Motor


Spec.
Battery: 2~4 Cell /7.4~14.8V
RPM: 1000kv
Max current: 30A
No load current: 1.7A
Max power: 430W
Internal resistance: 0.052 ohm
Weight: 102g (including connectors)
Diameter of shaft: 5mm
Dimensions: 35x36m
Prop size: 7.4V/11x5 14.8V/10x6
Max thrust: 1160g
 

We'll use a 3S Battery, and a 10*6 prop.

At maximum power it will draw about 300-330 W and 30 A

This will suit the model well

Battery selection:

Average current draw: 20 -22 A
In 10 minutes, it will use about 200 A-min
or 3330 mAh - so use a 3000 or 3300 mAh Lipo of 3S

Weight of motor: 102 gm
Wt. of ESC (40 A): 36 gm (http://www.hobbyking.com/hobbyking/store/__24562__HobbyKing_40A_ESC_4A_UBEC.html)
Wt. of LiPo (300 mAh): 239 g

Total: 277 g

If you use an engine:

Look at the ASP 21A exampled below

Weight 233 gm (http://www.hobbyking.com/hobbyking/store/__8990__ASP_S21A_Two_Stroke_Glow_Engine.html)
120 cc Tank w/ fittings: 60 gm

Total: 293 gm
 
So in conclusion, the weights are practically the same. The cost of the Engine would be slightly cheaper (you would need at least 2 LiPo's) and the operational cost would also be similar (a Lipo lasts about 100 charge/discharge cycles - hopefully ) and you can mix your own fuel

The main advantage of the electric in this case would be less hassle - no starting paraphernalia, no mess to clean up later; and less risk of reaching the field after a long drive and finding your engine won't start 

Thank you for such a great reply. 

Anytime 

Please note the calculation is based on the assumption it is a high wing trainer

Further, if you are going to buy engines or motors, go one size higher: you will have more versatility

eg go for a 25 instead of a 20 engine,
and a 3536-1250 instead of a 3536-1000 motor

High winger trainer. i have build it.
well for a high winger trainer 25 size engine plane will 9g avionics servo work.?

You can use 9 g for the Ailerons, but I suggest higher torque for the Elevator & Rudder - especially if the rudder is linked to a tail wheel or nose wheel steering. You could use 17 g servos for the Rudder/Elevator. Remember, Metal Gear Servos will give a little higher torque and increased longevity, and IMHO are well worth the extra money

Which model is this? The suspense is killing 

As said, sir the model is made by me only. Wings are expert, from vortex-rc. And fuselage is of balsa self made

Vortex RC wings and balsa fuselage?   

I would suggest you stick to an engine size 0.15 to 0.10 for your model. Your ASP 0.21 is bound to be way more powerful for your model.

Some pictures of the model would be appreciated.

Sandy sir, the weight? Will be 1.3-4 Kg.

Also has a 56" span

Sanjay Sir Vortex RC wings are foam wings with sheeting more akin to a glider wing profile. bound to have good glide characteristics if well balanced on CG. Further does not have reinforcements and is relying on the sheeting for strength. So I would recommend a 0.15 which will restrict the AUW to 1.4 Kgs and will do well with a 56" span and a good glide characteristics.

My cloud dancer 1.35 wingspan on ASP 0.25 around 1.5 Kg AUW is a missile in air. I doubt a foam wing can take that level of stress in air.

Sandy sir, your point is correct - but a 15 is too marginal. It will give max 200-250 W - not really enough: the engine will always be running at full or near-full throttle This is why I had suggested a 20. At the same time, if a person is going to buy an engine, I would always recommend a 25 rather than a 20, simply because there are many more models available for that size, the cost is practically the same, weight marginally more, and you do not always have to run on high throttle - fly on lower throttle!

A 20 is what is needed by my calculations as listed above. Even the simplistic formula of 100 W/lb for the 1.4 Kg model gives 308 W