calvino

I am wondering if a formula exists to find an equivalent nitro engine to an electric motor???? Even if there is a chart that would be nice

Ed Smith

Try here.


http://joshmadison.com/software/convert/

Ed S

calvino

neat, what function would I use on it???

sharpshooter223

that wouldnt tell you a nitro engine size for an electric motor size, that is just units of measurement conversions

calvino

ok, thanks though. Just currious

Ed Smith

It converts watts to horsepower, Or horsepower to watts. SO, if one is known or specified the other can be determined.

Ed S

iron eagel

easy...
750 watts=1hp
check out the hp rating of your glow engine and that tells you how many watts...

For example 1/2 hp = 375 watts
2 hp = 1500 watts

to figure watts the formula is volts X amps =watts
11.4 volts at 30 amp = 342 watts
batteries are in mill amps/hr
2000 ma = 2.0 amps

TLH101

My Feedback: (90)

Only problem is most glow motors are HP rated at unusable rpm, or just a"SWAG" number.

iron eagel

There is a plus to this problem, if you size your electric motor given the glow claims, you should have enough power for your plane...

Campy

My Feedback: (1)

As a GENERAL "rule of thumb" use the following (weights are ready to fly with batteries):

Get an electric outrunner with the following:

For sport flying 60 - 100 watts per pound of model weight.

For mild aerobatics 100 - 150 watts per pound of model weight.

For 3D 150 watts +++ per pound of model weight.

As I said, this is a general rule of thumb. The design of the plane and the airfoil of the wing will have a big influence on the watts needed. For instance, a Telemaster will fly very nicely on 60 - 75 watts per pound, MOST trainers will need 75 - 100 watts per pound.

United Hobbies (https://www.unitedhobbies.com/UNITED...?idCategory=86 ) has the watts available on a lot of their motors.

For the majority of 40 size planes I have excellent luck with the TowerPro 3520-6 and 3520-7, a 4s lipo, 60 amp ESC and a 12x10 or 13x8 e-prop. That normally produces around 650 watts and pulls about 48 - 50 amps.

TLH101

My Feedback: (90)

Well, OK, that never ocurred to me.

calvino

Thanks, just currious as I have a delta wing airplane and wanted to know what glow engine would power it as I was currious if it was cheaper/more powerfull than a brushless setup (even though UNITED HOBBIES, hear great only great things about what they sell, has a complete brushless outrunnner (ESC, motor, and prop) for $20 minus shipping.). Just currious, thanks for all the stuff.

sharpshooter223

yea, i would also like to know conversions for converting to glow

Ed Smith

I do not know what "SWAG" is. It is a fact of life that the max HP of a two stroke glow engine is reached at a fairly high RPM. To reach this high RPM smaller props are necessary. Whether the the smaller props are usable is a decision made by the user. Maximum HP is maximum HP. I cannot see any manufacturer quoting lower HP figures than the engine is capable of. It is incumbent upon the user to get an understanding of the relationship between Torque, HP and RPM.

Ed S

da Rock

Nowadays, look at the electric model you want to convert and then look for a similar glow powered model. Size and weight are the important parameters.

Keep in mind that if the model was designed for electric, it might not be robust enough for glow.

calvino

yeah, my plane is foam so, it may not be strong enough for a vibrating, oil spitting glow engine. It will probabaly be an electric for noise, ease by a total novice...

iron eagel

Da makes a good point about the structure of airframes verses power here. You can convert a glow to electric power but it is not wise to convert an electric to glow without extensive modifications to withstand the vibration of an IC motor.

One of the real neat things about electrics is, with minor modifications you can convert some "old time" rubber band and 1/2 a powered models to electric.

sharpshooter223

where there is somebody with no life whatsoever outside of planes, there is a way. i can see many electrics being able to be modified to glow, but what i was thinking of were the balsa build up kits not foamies, i dont really care for them. but when an engine doesnt tell you hp, how do you find it.

sharpshooter223

if it is foam then it is already made for electrics, why do you need a conversion for that?

da Rock

You don't find it. It isn't available. What you do is very similar to the technique of estimating used for the electric>IC "conversion". If the ultimate goal is to fit the engine to an airframe the look around at what engines are in what airframes. Match 'em up.

If all you want is some number, you're not going to get the true number unless you've got the lab equipment and know how to use it. That'll start with some weather recording tools and go from there.

Want someone to describe the entire process for you?
Build a small dynomometer that suits the engines you're going to test. (Or find and buy one that's suitable. Don't know of any myself.)
Record the weather for correcting the findings.
Run the engine and record the output.
Figure the torques generated. Correct it for the atmospheric conditions that matter.
Compute the hp's from the torques.

iron eagel

Campy's rule of thumb is perfect for what you are trying to do. look at the weight and desired performance and size your motor by that.
The same "rule of thumb" works for either foam or Balsa construction.
If you are near the edge of performance of a motor, go to the next larger size and you should be safe.

calvino

My consideration of an IC for my engine was out of curriousity... Does anyone know what a .069... would even work in as most planes require a .40-.50 on average. Thanks for the info, I guess you could find out what a plane would require by looking at planes with the same weight... Anyone ever built a nitro foamy??? probabaly not atempted due to vibration... Thanks though, mini t

iron eagel

An .069 would work in what is labeled a 1/2 A plane, check out that forum for more info, the herr engineering 1/2 A planes such as Chreokee, Cub, Mustang, A6 or Pitts sold by Sig would hold it.
As far as a foam aircraft with an IC motor yes it has been done although it required mods to the firewall and fuse to dampen the vibration.

sharpshooter223

there are many .40-.50 planes, but there are many electric sized aircraft that are great with small engines of the sort. i think 1/2a means even smaller engines though.

iron eagel

1/2 A typically refers to airplanes that fly on .10 engines or less. His .069 will fit in just about any 1/2 A kits Sig makes, there are others that would fly on his .069.
It might be a bit small for the Pitts, though it would be perfect in the Mustang or Cherokee..