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Oct 31, 2009, 09:56 AM
GM

St330 easy fly cg & question on motor-prop options


Gidday Folks,

The Chinese manufacturer, Sheng-Teng Co., advised me the CG "should be 70mm behind the LE".

My Easy Fly is a RTF version and the only change I made to it is my own colour scheme (pics included) and where I position the LiPo to test stability. I have found that sticking to the 70mm position results in the glider tending to nose dive without elevator input with or without power.

I don't think I've had any problems with the stock servos but then again I am not knowledgeable enough to really know. Though I have had some hairy flights with wonky stability where my inputs sometimes seemed to have little effect.

I broke my prop shaft when she nosed over onto hard ground so I need to either use a prop attachment, fix the motor or replace the motor. My preference is to upgrade to a higher Kv motor from the stock motor which I have always found to be good in still/light-cool air but challenged above that.

My questions are:

1. What type/size motor can I upgrade to, while keeping the stock ESC, and which will fit inside the available nose shell space? I would like to be able to put the nose's cut-away foam back on to maintain the glider's original shape/profile, and I will upgrade the ESC if necessary.

2. Perhaps I'm better off having the broken prop shaft replaced on stock motor and changing the prop & spinner?

All advice and opinions are welcome, thanks in advance.
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Oct 31, 2009, 10:37 AM
Registered User
Nice paint, i like it.
I have been playing with CG and found that the best place is 75mm to 85mm from LE. Because I maiden my easyfly with CG at 70mm i nose land and the flight was terrible up and down.. very dificult to do an horizontal flight. With CG at 75-85 it flies very well.
I bought TP-2409-18 HERE for replace motor when needed. Fortunatly i didn't need to replace it. They also have some replacement shafts for the 2409 motor. The motor size is same as stock one (+/-). Who allready replaced for TP-2409 reports that power is similar.
Take special attention to the firewall because if it is loose or "semi-broken" you will get a lot vibration.

Take care
Oct 31, 2009, 12:56 PM
Registered User
SoMoney's Avatar
Thread OP
Nice Paint Job! I'm going to paint the botom of my EF black also and this gives me some great ideas on mixing it up.... You going to do an FPV conversion too?


MOTOR REPLACEMENT: If your going to replace the motor, I would advise you to buy a dremel.

http://www.harborfreight.com/cpi/cta...emnumber=92880
These are $29US at Harbor Freight. When shopping a Hobby grade dremel make sure its adjustable speed (1-2 speed dremels are a pain to work with imo)
THE DREMEL IS THE #1 TOOL YOU WILL EVER EVER EVER EVER NEED!

The motor mount/disc they use is made of flimsy balsa and cracks easily.
1. Go to a Hobby store and pick up a piece of thin ply
2. Place the original motor mount disk on the ply and trace a circle.
3. if you have a hack saw cut AROUND the traced area (dremel can do this to but be careful)
4. With the DISC CUTTER attachment cut away the ply wood until you perfectly match the motor mount.
5. Place the original motor mount over you new one to compare size.
6. With the Sand Paper attachment sand the ruff edges until you have a perfect match.
Last edited by SoMoney; Oct 31, 2009 at 01:04 PM.
Oct 31, 2009, 02:56 PM
Registered User
SoMoney's Avatar
Thread OP
Quote:
Originally Posted by Tarz
Take special attention to the firewall because if it is loose or "semi-broken" you will get a lot vibration.
Take care


I must agree with that statement. I unknowingly loosened my motor mount and had horrible vibration followed by my motor tearing loose from the nose section! My Current motor mount is hot glued and I also used strips of 3M packing tape pulled back against to body to secure just in case... The cowling over my electric motor is just for looks.
Oct 31, 2009, 03:56 PM
Registered User
Is the prop a 10x8 ????
Oct 31, 2009, 11:26 PM
GM

Thanks Tarz


Thanks Tarz, I'll look up the motor or an equivalent in Oz.

Quote:
Originally Posted by Tarz
Nice paint, i like it.
I have been playing with CG and found that the best place is 75mm to 85mm from LE. Because I maiden my easyfly with CG at 70mm i nose land and the flight was terrible up and down.. very dificult to do an horizontal flight. With CG at 75-85 it flies very well.
I bought TP-2409-18 HERE for replace motor when needed. Fortunatly i didn't need to replace it. They also have some replacement shafts for the 2409 motor. The motor size is same as stock one (+/-). Who allready replaced for TP-2409 reports that power is similar.
Take special attention to the firewall because if it is loose or "semi-broken" you will get a lot vibration.

Take care
Oct 31, 2009, 11:31 PM
GM

Thanks SoMoney


Thanks SoMoney, I appreciate the advice on the Dremel and the procedure for the replacement of the mounting board. Your photo is really helpful too, did you cut the top away and return it after placing the new motor? What is the motor you show, is the same one you showed in one of your posts way back in this thread?

Quote:
Originally Posted by SoMoney

I must agree with that statement. I unknowingly loosened my motor mount and had horrible vibration followed by my motor tearing loose from the nose section! My Current motor mount is hot glued and I also used strips of 3M packing tape pulled back against to body to secure just in case... The cowling over my electric motor is just for looks.
Oct 31, 2009, 11:36 PM
GM
SoMoney, RE: your question am I going FPV?

I'm interested in the freedom and new experience that FPV offers but it is too early in my piloting experience and budget to take that step. I have found the content of this thread to be fascinating and certainly an inspiration for future exploration.
Oct 31, 2009, 11:59 PM
Registered User
SoMoney's Avatar
Thread OP
Quote:
Originally Posted by gmeekan
Thanks SoMoney, I appreciate the advice on the Dremel and the procedure for the replacement of the mounting board. Your photo is really helpful too, did you cut the top away and return it after placing the new motor? What is the motor you show, is the same one you showed in one of your posts way back in this thread?

Yes, When I was bench testing my KDA2220L A22-20L 1000kv I found the 10x8 prop I was swinging puts out a lot of thrust! The motor tore away from the plane, the balsa motor mount went with it tearing the entire front nose section right off to where the mount sits.
Yes I cut away the top (that wasnt torn away) and returned it after with tape.
Nov 01, 2009, 07:38 AM
GM

St330 easy fly information - manufacturer's website, english manual & review


ST Model is the ST330 manufacturer. Their website is at: http://www.sheng-teng.com/

English Manual:

The ST Model website now has an improved English manual. Improvements include how to set the ESC for prop braking on page 4, a new flying speed spec on page 1 of 12 m/s, and better grammar than the first version which was truly awfull but this version is still quirky in parts.

There is also a much better English version at: http://www.modelflight.com.au/manual...structions.pdf . However, it is a translation of the very first version and does'nt have all the info of the ST Model website latest version (e.g. 4 pages v. 6 pages).

Review:

An Australian RC soaring club newsletter, edition dated April 2007, has a review of the ST330 with some interesting comments about upgrading the motor and prop combination. I have'nt found any other reviews of this glider except for the comments in this thread. Worth a look on pages 6 & 7 of the PDF: http://www.varms.org.au/images/stori...ivityapr07.pdf

Happy reading.
Nov 01, 2009, 07:58 AM
Registered User
Nice review... and the CG found in the review is same as i found in mine

Thanks gmeekan
Last edited by Tarz; Nov 01, 2009 at 10:19 AM.
Nov 01, 2009, 07:36 PM
Registered User
DayDream's Avatar
The 80mm mark worked well for me, thanks Tarz



I had my maiden fight yesterday and flew again today, and it was pitch perfect
the problem I'm having with this bird, as you were saying SoMoney, is the roll authority
I would like to eventually use the rudder channel for pan, but I found I needed the rudder it to keep the plane up right
Large wings and small ailerons give's the wind more say in the roll than I do.
maybe enlarging the ailerons could fix this problem.

The easy fly also seems to have a speed it like to fly at where it handles well, especially when you cut the power and do some gliding! the plane seems to lose some stability thou, when the prop is spinning.



SoMoney
Quote:
The motor. I dont think anybody is truly happy with their motor because this is a BIG BIRD and swings a BIG PROP! Try not to exceed 1200kv though as I have found the Easy Fly looses aileron authority at high speeds.

The next time I crash my Easy Fly or the motor mount loosens up I will replace my KDA2220L A22-20L 1000kv motor with a smaller AXI 2212 1100kv I have.
Too late! I already have a KD A20-22L on the way from HobbyKing.
I was hoping a 10X6 would have good thrust with less wash. and I have a mount seem cooked up to handle the bigger motor.
Last edited by DayDream; Nov 01, 2009 at 07:49 PM.
Nov 01, 2009, 10:36 PM
Registered User
SoMoney's Avatar
Thread OP
I think you'll be okay... I doubt you'll have the same issues as me....... It's possible my A22-20L is bad and pulling more amps than it's suppose too. The original ESC that came with the EF went up in smoke before I even hit the throttle on this motor so its definitely suspect..
Nov 01, 2009, 11:16 PM
Registered User
DayDream's Avatar
I have a 30Amp ESC out of my Trojan, and I have a less aggressive blade. also I don't plan on keeping it a full throttle for extended periods. guess I will find out in 10-45 days!
btw I was wondering what type of paint you used on you plane? just spray paint?
Nov 02, 2009, 10:51 AM
Registered User
DayDream's Avatar
I was thinking about it, and I had an idea on how to free up the rudder channel for pan but keep the extra control surface. so I thought I could just tie the rudder in with the ailerons. witch I think is a good Idea, a sort of auto rudder, unfortunately I installed a reversed servo in the tail. and the way I put the tail together it would be imposable to pull out the wire and just replace the servo.
so I either need some way or rewiring it or slicing it at the servo.



any ideas?


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