Engine size needed
- Thread starter Chuck Ray
- Start date
I’ve not touched a glow engine for some time. My recollection 15 size engine is a bit small for a 5 pound plane. I’m thinking a took a 30-40 size engine is more appropriate.
Here are some guidelines that may help. It’s the total flying weight of the plane that you need, including motor and battery.
• 50 to 70 watts per pound is the minimum level of power, good for park flyers and lightly loaded slow flyers.
•70 to 90 watts per pound is perfect for trainers and slow-flying aircraft.
•90 to 110 watts per pound is good for fast-flying scale models and some sport aerobatic aircraft.
•110 to 130 watts per pound is what you want for advanced aerobatics and high-speed aircraft.
•130 to 150 watts per pound is needed for lightly loaded 3D models and ducted fans.
•150 to 210+ watts per pound gives unlimited performance for any 3D model.
TheFlyingBrit
Legendary member
Turnigy G46 Brushless Outrunner 670kv (.46 Glow)
Battery: 4~5 Cell /14.4~18.5V
RPM: 670kv
Max current: 40A
No load current: 10V/3.9A
Current capacity: 55A/15sec
Internal resistance: 0.04 ohm
Weight: 303g (not including connectors)
Diameter of shaft: 6mm
Dimensions: 76x50mm
Required;
60A ESC
4S~5S Li-Po / 12 ~ 16-cell Ni-MH/Ni-Cd
12x8 ~ 14x10 prop
Suitable for sport and scale airplanes weighing 4 to 7 pounds (1.8–3.2 kg).
Battery: 4~5 Cell /14.4~18.5V
RPM: 670kv
Max current: 40A
No load current: 10V/3.9A
Current capacity: 55A/15sec
Internal resistance: 0.04 ohm
Weight: 303g (not including connectors)
Diameter of shaft: 6mm
Dimensions: 76x50mm
Required;
60A ESC
4S~5S Li-Po / 12 ~ 16-cell Ni-MH/Ni-Cd
12x8 ~ 14x10 prop
Suitable for sport and scale airplanes weighing 4 to 7 pounds (1.8–3.2 kg).
Hai-Lee
Old and Bold RC PILOT
The old conversion formula for gas to brushless was to multiply the engine size expressed in cubic inches by 2000 and the result was in watts.
So .1 cu in would be a 200 watt motor and so the bird was defineitely no speed machine.
To match Kv determine the maximum revs of the original motor and divide by the battery voltage you intend to use. So a motor that rev'd out to 12,000 rpm would translate to a 1000Kv using a 12 volt battery pack.
This would all allow you to use the original spec propeller.
In this day and age of ridiculous power houses the old rules just allow you to know what could be considered as the MINIMUM motor power that you should use.
Have fun!
So .1 cu in would be a 200 watt motor and so the bird was defineitely no speed machine.
To match Kv determine the maximum revs of the original motor and divide by the battery voltage you intend to use. So a motor that rev'd out to 12,000 rpm would translate to a 1000Kv using a 12 volt battery pack.
This would all allow you to use the original spec propeller.
In this day and age of ridiculous power houses the old rules just allow you to know what could be considered as the MINIMUM motor power that you should use.
Have fun!
Hai-Lee
Old and Bold RC PILOT
Been a little busy in preparing case against local club . Managed to file at the supreme court last week.
The club is ruled by an untrained knowitall who can't handle someone with knowledge. Sadly for him he overstepped the legal line.
Not been flying for about 6 months now but still teaching and helping my students.
I have been on the forum but mostly just observing as I spent my time doing legal research.
Hope to get back to it in the next 6 months or so.
Have fun!
2nd question if you don’t mind.
What size servos? I need rudder and elevator which can be standard size because there is plenty of room.
I haven’t done ailerons before. I was thinking of a central server 2 L linkages.
Thoughts?
slowjo
Master member
also individual adjustments/centering
