Choosing the right RC motor with specific requirements like being light, powerful, and having a 5:1 gearbox for narrow installation conditions can be a bit challenging, as it requires finding a balance between these factors. However, I can provide some general guidance on what to look for and recommend a few options that might fit your criteria.

Tenshock EDF 1515-15T-3770KV with Micro Edition 5:1NL is the ideal choice for your glider

Size and Weight: Since you mentioned narrow installation conditions, the motor should be compact and lightweight. Brushless motors are often preferred for their high power-to-weight ratio.

Power: The motor should provide enough power to meet your requirements. Brushless motors are known for their efficiency and power output.

The high quality Reisenauer  5:1 gearbox ensure that the motor  is durable and trustable solution for your model

Data:
Weight: 107g
Pole: 4
Motor Ø: 28,0mm
Motor lenght: 60mm without shaft + shaft 17mm
Shaft Ø: 6,0mm
Hole circle: 14mm, 3xM2,5
Lipo: 2-4
rpm/V: 768 measured with timing 6°
Electricity max.: 60 amps
max. power: at 11,1V 660 watts, at 14,8V 850 watts
Timing: 6-10°
Frequency: 8-12khz