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Need help choosing motors/batteries etc. for planes

#1
Hi all. I'm new here but I hope y'all can help.

I have several old planes I built in the late 1980's early 1990,s and built them stock using the motors that came with the kit. Because my planes are over 25 years old now (planes are near perfect condition though) the radios and motor systems are obsolete, so I need to replace all the "guts".

My question is, can you all recommend a low cost alternatives/upgrades to replace everything in the airframes? I need new motors, radios, (probably servos...? most of the planes use micro or mini servos), ESC's and receivers.

Because all the standards have changed drastically over the last 25 years I have no idea what modern motors and power systems I would need to directly replace the old equipment. I'd like to find a "primer" for understanding such systems so I can understand what type/size motors and battery packs work best with a planes's wing area and weight etc.

The planes I have are the following:

Midwest "Aero-Lectric"
Great Planes "Spectra" electric glider with Graupner folding prop,
Carl Goldberg "Mirage 550"
Great Planes "ElectriCub"
Midwest "Electric Hots".
Great Planes "Electro Streak" (unbuilt)
Sig Tri-Star (unbuilt)

All of these planes used the 550 or .05 size electric can motors and the ancient 7.2 volt 1300 mAh Ni Cad battery packs abd HAD (at the time) all up flying weights of 3 pounds or less.

I'm seeing how technology has made motors and batteries a lot more efficient these days so I need to know what motor systems and battery packs I can use as a direct replacement for these old systems in my still really good condition planes. I'd like to just buy one radio (probably 6 channel) with multiple receivers with ESC's and motors and battery packs that will work in all planes. Also a suggestion of a quick charger for these systems would be great too. I'm interested in doing this for the lowest cost possible, and expecting that most of what I need can be found at Hobby King.

Hoefully all these systems can also decrease the amount of weight and wing loading to allow the planes to fly slower than they did too, as I like very slow flying planes (with the exception of the Hots and Electro-Streak, of course, which were designed to be fast).

Thanks for reading. I can also be reached directly at "jim@smallartworks.ca"

Please let me know if you have any hints or suggestions for me.
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#2
First of all Do NOT just replace things because you want to upgrade but rather be selective and use what still works. Motors that worked before will most likely still work. The battery packs, 7.2V could be replaced with 2S Lipo packs, (7.4V). The radio gear is best updated. The servos do suffer from age and so replacements whilst not compulsory are recommended.

Battery chargers are a matter of opinion so just select a good balance charger.

Replacement motor selection is a complex question, my simple rule is for general flying I use 100 Watt per pound more for high performance and a little less for sedate flying. If you can select a motor to swing a prop the same as the plane was originally specified to use.

Servos could be reusable or as recommended go for a suitable size equivalent.

Radio system from HK I suggest the Turnigy iA6 2A as the performance is very good, can support 20 different models,is cheap as, and the receivers are quite inexpensive.

Alternate battery packs and ESCs are chosen for voltage & current required as well as the flight duration wanted.

As for the flying slower, weight is a factor but the main factor is the original design. Wing profile and area are selected by the designer for a flight/performance envelope and so making a plane lighter will slow it a little but not as much as you think. Making a plane slower and lighter by reducing the power available for flight is flirting with danger and could turn a great flyer into a real dog with which you will flight constantly just to keep flying.

I hope this helps!
 

Ron B

Posted a thousand or more times
#3
I am not sure but in addition to the above you will need to replace the esc's as they may not work with todays electronics
some one with more knowlege of the older electronics might be able to help here as I went from gas 42 yrs ago to electric just 3 yrs ago