Gearboxes are new to me and I have no clue what I need. I have a 6V speed 400 Zagi motor, 20 amp ESC and four 8 cell KR-1700 AU stock Zagi battreys, some 5x4 Zagi props and some 5x5 props. I am looking for a power boost without breaking the bank (the most bang for the buck). Can I use any of these gearboxes, if so witch one? Also can I use the props I have or do I need to get a bigger prop. for the GB....Thanks....R.. http://www.hobby-lobby.com/gear400.htm Also if I use a GB will the 400 will the combo weigh less than a Retom 480 motor?

Yes those gearboxes will fit, but which ones correct depends on how big a prop you can fit on there.

The bigger the prop, the bigger the reduction ratio you need, but also the greater the chance of breaking props on landing.

These gearboxes will add about 1 oz, or around the same as the 480 would add.

A good compromise would likely be around a 2.33:1 ratio with a 7x7 prop. Less amps and better climb than stock.


Dean in Milwaukee

Someone please correct me if I'm wrong, but I though a Zagi was easy to stall, and very tough to recover.

Wouldn't a gearbox make it fly too slow?

"Someone please correct me if I'm wrong, but I though a Zagi was easy to stall, and very tough to recover.

Wouldn't a gearbox make it fly too slow?"



Its fairly likely that it would actually fly FASTER.

The stock zagi powertrain produces pitch speed in the low 70's, or almost twice as fast as the plane can go with the stock powertrain. This extra pitch speed is attained with the given power level by sacrificing thrust via the small prop.

Gearing down to a more realistic pitch speed, say around 50-55 mph, frees up power to spin a larger prop to create more thrust.

This extra thrust makes it climb faster, and gets it going again faster to help recover from stalls.

Think about it. If you have enough thrust, it won't stall at all, but will instead climb out.


Dean in Milwaukee

Well, right now I am running the retom 480 with a 5x5 prop. and I would like a little more speed (not much) and more power. Like I said I am new to gearbox use so how does this work, bigger prop spins slower = more power = less speed? How much do I need to prop. up and get a little more speed and for sure more power? I know burshless is "the way to go" but I dont have that much $$$$ Is there anything I can do? I just thought that a gearbox mite be the answer....Thanks,....R.. p.s. Dean in Mil, I can go with whatever size prop I need, as you know with the Zagi its just a question of cutting more foam away. Thanks for the help What about the MPY345 tward the bottom of the page? Also what prop?

The 5x5 is'nt a good mach for the motor and plane.

A buddy of mine had great luck using a dymond 480, which belive is the same motor you've got, with a 6x4.

His plane would fly on the level about the same as a stock zagi, dive a little slower, but climbed WAY better.

Flight times were about the same.


Dean in Milwaukee

I used the black can 480 with the graupner 1700 series 2.3 gear for quite some time in my zagi with 8 cells (stock packs) I used apc 8x6 sloflyer prop . It was faster than stock and cured the slow speed stalling. I used c/a glue to mount it to the zagi tray with the offset on top and the can in stock position (this keeps the prop from breaking)and does not affect pitch.This setup will be fast enough to give you a whole new set of problems Good luck James btw no need to trim elevons

Thanks all,

One of these days I'll put this Razor kit together.

John

O.K., so if I get a 2.33:1 gearbox, what size folder should I use,8x6, 9x6?.....R.....

8x6 will do fine and you do not need a folder unless you want to reduce drag for gliding . 9x6 is too big your speed will go in the toilet and I doubt it will help climb .The set up I recomend is tried and true . James

Randy
8x6 will do fine and you do not need a folder unless you want to reduce drag for gliding . 9x6 is too big your speed will go in the toilet and I doubt it will help climb .The set up I recomend is tried and true . James


James, I was planing on using the 6V 400 (lighter weight) for this set up, do I need to use the Retom 7.2v 480 insted? As far as the folder goes, I kinda like them because when you land with power off, it folds so it wont break. I can get the same gearbox and prop for the 400, will this work, or do I need to go with the 480 motor gearbox and prop? I gotta deside soon as I would like to order them by Friday. Thanks again for all your help,....R.....

Just put the gearbox and larger prop on the existing motor.

Well, I have a 6V 400 and a 7.2v 480, the 400 is alitle lighter, and the 480 is alittle heaver but with alittle more power. If I go with the 400 with a gearbox it would be the weight as the 480 with out a gearbox, so whitch one?? I have both.......R........

A zagi is a 480 in/sq wing.

An extra oz or three is virtually irrelevant.

Use the 480 with GB. More power, less amps.



Dean in Milwaukee

Thanks all, Looks like im going with a 480, 2.33:1 Gearbox and a 8x6 prop. Thanks again, ..R....