Hey,
i will get into gas and nitro eventually and wanted to know which engine to buy.
I will me making trainer and scale type aircraft from corro as sanjay sir makes.
Please tell me what are the factors that go into selecting a engine?
regards,
           Prabal

1. Power requirement
2. Desire
3. Budget
4. Glow? 2 stroke? 4 stroke? Petrol? Diesel? Wankel? Turbine? 
5. Ease of availability

Come on Prabal.
Such an open ended question can only get
A. No response
B. Everyone suggesting whatever they think right, without any correlation to your requirements.

My suggestions:
1. Mills 0.75
2. Cox 0.049
3. OS LA 0.10, 0.25, 0.40
4. Sharma engines

ok guys! lets get specific!
1) the engine should be able to suffice plane of 2 kg.
2) Budget not above 6000
3)No idea. i think a 2 stroke would do d job.
4) Should be available at online store.
Also mention requirements in addition to engine ( accessories...)

Go with the os 46 ax / os 55 ax , both will be good enough . Two strokes will give you more power but are not as fuel efficient as the four strokes . Two strokes also are easy to maintain and tune .

@prabal276,
Answers to your questions are easily available, if you take the trouble to search.
Eg, OS46 available at RCDhamaka for Rs5599.

As regards accessories, if you are an aeromodeller, you can easily think of everything without asking.
Lets try.

Engine mount
Mounting bolts, lock nuts, thread lock
Pushrod and clevis for throttle
Fuel tube
Fuel filter
Clunk tank
Fuel pump (squeeze bottle, manual, electric)
Fuel
Glow booster / clip / battery
Power Panel
Power supply
Glow plug spanner
Prop
Prop wrench
Spinner
Chicken stick/finger guard
Electric starter and power supply
Rag, to stop engine when it starts backwards
Rag and Colin to clean fuel residue off the plane
Helper to hold plane while starting etc
Fire extinguisher
First aid kit, at least band aid
Ear muffs
Insurance
Permission to fly
Experience.

I'm sure you could have thought of all this yourself.
So I'm curious about why you posted this query.
You're not alone.
Lots of guys post queries for which answers are readily available with a little effort.
Regards.

@prabal276,
Aah, must apologize.
Just noticed in your profile that your  RC skills level is 'ADVANCED'
It is therefore not proper for an 'intermediate' guy like me to offer you advice!
Regards, once again.

that must be by mistake.
it should hang around in the beginner category.
The only thing i know about gas and/or nitro is that they work on fuel.....

 i Know that i can search rc bazaar and dhamaka but i was confused with which engine to go with. I dont know the importance of cc and other things in selection. I am not so experienced and never have seen a real rc engine ( not counting photos). Nor i have time to research. S.a '1 are going on right now( i am in class 9). i can only have my computer on for 3-4 mins every day...(sometimes more)

On the net when i searched on electric power ; lot of instructions were present. When i search for gas, there are none and even if there are they expect you to know the terms of every bits and pieces.
Cant it be like=
To fly a plane of xx kg, you need a engine of specs xxxxx
and in addition to that you need: x y q in which x=blah blah y=blah blah q=blah blah.
when you get your engine you have to get it started by :
1)hfgd
2)nfgt
3)fghgf

AN EXAMPLE:

ASP S46 AII

SPECIFICATION:
Bore: 22.25mm
Stroke: 19.28mm
Displacement: 7.49cc (How does it matter?)
Output: 1.30kw/17,000rpm (what is this ?)
Practical rpm: 2,000-17,500rpm ( now what is PRACTICAL rpm)
Weight: 412g

REQUIRES:
* Glow plug GP1 ( what is a glow plug?)
* Propeller 10x6 ( why this specific prop.?)
* Glow Fuel
Regards,
          prabal

Prabal you better finish your sa1 then you can research with a free mind. If you research now you will not be able to concentrate on your studies because you will be thinking about rc 90% of the time.

youre right....
only 2 are left! last on 24. It's math
what about you??

For a 2 kg airplane a os 46 ax or a 55 would be sufficient. Starting , running and maintaining a nitro is no rocket science.
1 - get a engine
2 - get a engine mount
3 - secure the engine to the engine mount , with proper hardware.
4 - run the fuel tubing , for both the engine and fuel tank .
5 - get a glow plug igniter
6 - make or buy nitro fuel .
7 - get a suitable propeller (make sure its for nitro)
8 - secure the prop to the engine .
9 - prime the engine (this will get the fuel inside your engine)
10 - place your glow plug boster on the glow plug .
11- flick the prop , your engine should start .

ok.
thanks. will check everything on 24 sept.

bump .
Did you settled on any ?
What bout sharma diesel ?

not right now.
Sticking to electric

Generally the simplest way to select an engine is to see the designer's recommendations!

If you are doing your own design, it would mean you have enough experience to also select an engine

Nonetheless, a good starting point is to select a prop! This would of course be based on the model

eg for a trainer, you would want thrust ~= model weight, power about 80 - 110 W per pound (depending on high wing trainer or shoulder/low wing trainer)

For a 3D model, thrust > 1.5 model weight, power about 250 - 300 W per pound

Use RC Tools or any other RC Calculator to determine the rpm, thrust, and power needed for various prop sizes. Having selected the prop, then based on the RPM, and Power, look for an engine that will be able to swing your selected prop at the RPM needed

This, BTW, is he same procedure I use for selecting an electric motor too 

Remember, for a slow flying trainer, select a prop whose diameter will give the required thrust, and pitch will give the desired speed. Note that the effect of diameter on wattage and thrust is much more than pitch

e.g.

a   10*6 at 10,000 rpm @ 30 deg C: 1.2 kg thrust, 300 W
an 11*6 at 10,000 rpm @ 30 deg C:1.75 Kg thrust, 440 W
a   10*5 at 10,000 rpm @ 30 deg C: 1.2 Kg thrust, 250 W

thank you for the detailed explanation sir!!

maybe wrong place to ask that which could give more flight time a engine or electric on same plane. Like a trainer

Quote from: Tanmay.mathur on March 30, 2016, 04:44:15 PM
that which could give more flight time a engine or electric on same plane

engine runs on fuel
and electric system depends on the lipo battery Mah.
I do not think that your question can be answered as the power sources are different.
(If you understand what i want to say. to compare time; both of the power systems should run on the same fuel/energy source so that output results can be calculated.but that's not possible! so you cant tell)
Regards

.
(text removed)

Prabal,

When one buys an engine, it is quite some time before one considers selling it, unlike electric motors. The average love-life of an engine, imo, is about 3 planes. If I were in your place, I'd buy an engine that is a known and recommended one, starts up easily (they just do not start as easily as electric motors), is easy to tune, so I can use it on atleast 3 builds before I decide to move on to something else. So I'd think the other way round, get a reputed engine s.a. OS/TT/ASP (in that order) and choose my builds around those engines.

As for the power metrics, the rule of thumb is a 0.46 c.i. with the right prop combo will churn out about 746 watts (1hp). It does largely depend on the prop chosen.

In elec setups, the power generator and energy transformer are different, battery and motor respectively, and so one has a rather versatile control over selection. With fuel engines, the power generator and energy transformer are the same unit so the prop heavily decides how the engine is going to convert fuel combustion to thrust.

Flight time, ball park comparison, yes engines give longer flight times, and are RTR the moment fuel is refilled. There are more variables in the equation for sure, but that would be a typical answer.

All in all, fly with guys who are into engines, talk, discuss, communicate and learn, experience is the key here.

Thank you girish sir for your advice!
i am not getting into engines anytime soon now. my field is too small (Railway ranji ground) and there are joggers out here.
I do not have the resources to visit bhondsi.
So no engines for me.

Okay sir got your point.
What are your opinion about toki for beginner