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Looking for a Mentor

osanbob

Junior Member
#1
First of all thanks to anyone who is willing to help. I have a hobbico Superstar Select (Trainer/GLOW). I have placed the stats below to show which kind of plane I am talking about.
SPECS: Wingspan: 60"
Fuel Tank: 10.5oz
Wing Area: 660 sq. in.
Wing Loading: 19oz per sq foot
Fuselage Length: 50"
Weight: 5.5lbs
Center of Gravity: 3 - 3.5" (71 - 89mm) from leading edge of wing measured at the fuselage side Airfoil: Flat-Bottom High-Wing
REQUIRES: Engine: .35-.46 (2-stroke)

I have had this plane for a couple years and I have only run up the gas motor once. I really did not enjoy messing with the fuel and starting the motor. I have seen a quite of few folks switching over to electric. I dont beleive it is to difficult but here is part of my problem. I live in Korea and actually there are not but a few hobby shops and to find someone who speaks english enough to mentor me through this task are few and far between.

I am looking for someone that can give advice and work with me until my project is done and to be able help me understand what types of motor mounts to use, pushing the firewall out to the desired depth, which motors would handle a 6 lb plane. The plane came with everything. All I needed to do was to buy fuel and mount the wing. All servos were mounted, reciever, battery pack for the reciever and servos. I would like to use everything in place if possible. I am willing to take close up pictures and measurements to better describe the task if someone chimes in.

Any help is greatly appreciated.

Thanks guys/gals

Osanbob
 

FlyingMonkey

Stuck in Sunny FL
Staff member
Admin
#3
The standard conversion tip for going from glow to electric is as follows...

Use 75 W/lb. for mild sport models and trainers. Use 100 W/lb. for nonaggressive aerobatics. For aggressive aerobatics, use 125 W/lb. and you can use 150+ W/lb. for 3D and wild flight modes.

So, you could use the easy conversion of 100 watts per pound. For a 5.5 pound plane, you would want at least a 550 watt motor.
 

pgerts

Old age member
Mentor
#4
Sorry that you dont like the glow but I do understand you.
First question : is this your first plane or do you fly electric RC planes?
If this is your first plane you really need help with the flying/training more than converting the plane to electric.
If you find someone to train you they will also help you with your glow engine. There are more flying time with a glow model if it is your first plane and you have not got some batteries and charging equipment to charge on the field.
You only need a bottle of fuel, a charged "glower" and a charged receiver battery or two. The 40-engines are normally very easy to start if you know how to do it - a mentor will do it for you.

Those 40-trainers are not so smart to convert to electric if you dont know how to build. You need a battery place where you can replace the battery without disassembling to much of the plane. A 4 or 5 cell 4000-5000 mAh battery will not normally fit where you have your tank today. If you have a smaller battery you might have problems getting the CoG right.

I have a similar conversion of a 40-trainer to electric
using this motor http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=16231
and this controller http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=18010

I stripped almost all of the fuse from the covering and made a lot of light holes in the back to make the plane lighter and better suited for electric. A lb less wieght does a lot to the speed (low) as i am using a less capacity high C battery.

I also converted a 40-trainer from electric to glow and it is one of my favorite planes in that size and category.
 

osanbob

Junior Member
#5
Hey thanks. This is exactly the type of help I needed. I did watch the video from your earlier post. That is actually why I started thnking about converting. They made it seem so easy. Maybe that is my real problem is that I am making it hard. Thanks. Look forward to talking with you about other items I am sure I will run into.
 

osanbob

Junior Member
#6
Thanks for the reply and the great info pgerts. I actually have flown both electric and gas in my past. My father who was really into the hobby got me started. I just never have been comfortable with the gas planes. The engine on this one really was not bad starting. I think it is just a personal "nervousness" about the spinning prop and trying to make the adjustments. On the electric, I know can hurt you just as bad but I knew that I am not a half inch from the prop at full speed trying to peak it out. I think I am going to take your advice about getting rid of some of the extra weight and then recover. I have been able to get the engine and the fuel pod out with any disruption and I am counting the grams that I will need to replace to readjust the CG. One of the questions I will have for anyone listening is how do you match up motor to speed controller to batteries. From the earlier advice from flying monkey he showed that I will need at least 550 watt sized motor. Right now I am thinking that I will remain right about the same weight so if I needed a 550 is that they same for brushed or brushless? What size battery would I need to run to get 15 minutes out of it? I guess I should go ahead and ask now, on the controller, I see 8amp, 15 amp 20...30..what is the equation to match all this up? Sorry about asking so much but I want to do it right and with me having to order everything and not being able to sit and talk at a store I guess I am just trying to have someone say the best way is. Thanks
 

pgerts

Old age member
Mentor
#7
.. is that they same for brushed or brushless..
I do not imagine that anyone is considering any brushed motor in that size today unless you really need the weight for a special glider start. All standard motors today are brushless.

The specifications for the motor tells the voltage needed.
A smart way to look at it is to aim att no more than 50 Amps for "normal use". Better to get more cells and higher voltage up to 8 cells when you start to increase the current to more amps. Special applications might have a lot more than 50 amps.
It is no problem to use a speed controller with 70 or more amp rating to a motor specified for 50 amps.

Example 550 W is 55A at 10V but i would preffer 4 cells with 14 volts for this power setup.

The flight time 15 minutes states a battery with a capacity of 140 wh... But you are never using 100 % power on a trainer, more like an average of 25% making 35Wh. 4 cells gives 35/14 approx 3000 mAh capacity.
On a windy day you will use a lot more power and get less flying time.

There is a completely different calculation on another type of plane like a ducted fan or a 3D.

As for glow - there are ways to avoid the spinning prop at full speed - never adjust the needle at full throttle, make it at idle and then rise the plane and give thottle.
Another thing is to move the needle to a safer place away from the prop like most OS LA engines have. As you say - the electric propeller is not less dangerous as it has a lot of power and is normally a lot sharper.
 
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osanbob

Junior Member
#8
Thanks for the help. I am taking all the notes down. I found a program today that helps and it is backing up the equations you are teaching me its called motocalc. Not sure how good it really is but it is matching what you are saying about motor size, batterys and ESC. You guys probably dont need this becuase you already know this stuff by heart.
 

pgerts

Old age member
Mentor
#9
Motocalc is an old and very good tool to use together with experience.
Different pilots have a lot different styles of flying so energy consumption is really hard to calculate other than when you are using 100% of power.
 

Ak Flyer

Fly the wings off
Mentor
#10
Different pilots have a lot different styles of flying so energy consumption is really hard to calculate other than when you are using 100% of power.
Exactly. That's one of the hardest and best part of building this stuff. There's a million ways to do things and no perfect answer. You can tinker and play with the numbers until you get what you want, then find out a little later that you want something different. All part of the fun.
 

osanbob

Junior Member
#11
In one of the reponses above it was said twice now that my motor should be approximately a 550 and good advice about the 4 cell was given. However, I still have a question becuase it was said that there are many ways to accomplish this. I know that more power is better than not enough but what are the limits. When I went through the motocalc it gave me a lot of examples of motors in the 600-800 size. I understand I need more battery and it also said I should use a 4 cell 3200. With all this said I am leaning towards more power becuase in the advice section it talked about grass and short strip take offs. I need to deal with short runways and none are paved. So its dirt, gravel, grass and not much room. Can I get your thoughts? The weights are not much different but am I creating a different problem by doing this. Trying to settle on Motor, ESC and battery setup so I can order from the states. Thanks guys.
 

pgerts

Old age member
Mentor
#12
You did not check my link http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=16231 to my setup for a similar 40-trainer - lifts the plane in a few meters in grass on half throttle or less ;-).
The problem might be that you might rip off the firewall if it is not secured ;-) I did - have to reinforce with fibre glass/epoxi or aluminium corners.
4 cell or 5 cell will work. I am using only 2500 mAh but it is no problem with 4000 if you balance the plane according to the battery weight.
As you can read on the bottom line - i dont like heavy planes for my type of flying (close, low and and slow in the turns).
The vid is a friend of me but the flying is a little similar except for med flying more inverted and immelmans etc.
http://www.youtube.com/watch?v=6xc_abTd4Z0&list=UUgKDtta9uTjFjtqvnK6WUYA&index=1
Go on to 5:30 where the flying starts - the time before is starting the glow engine ;-)
 

osanbob

Junior Member
#13
I have only been comfortable with slow more to scale flight rather than speed racer myself. So I hope to end up with this project a good looking trainer converted to electric with enough power to take off in my close quarters. I think I am going ahead and order my motor and esc this weekend and order my batteries in country. They seem to be pretty easy to get ahold of but the selection of motors on hand in the local hobby shop is sparce. Thanks for the help, I will be updating my progress and asking for more help I am sure. Thanks
 

osanbob

Junior Member
#14
Sorry guys new question and it may be really lame but I need to ask. If I decided to purchase a new DX8, will it work with my older servos. I have an old (at least 8 years) futaba 4 channel (skyport) Radio and reciever with S3003 servos. Is it as simple as buying a new Radio and reciever box and just plugging in the servos? The receiver I had in the plane had its own battery since I did not have an electric set up. From what I see now I need to run my radio gear from the 4 cell I am using for the motor. Thoughts. As always thanks a million for your advice.
Osanbob
 

osanbob

Junior Member
#15
for those of you that have been monitoring I am getting ready to start taking pictures of the transformation if you are interested. I am loving finding something to take my mind of of work. In my current job it seems that I am always working and but this focus is making me take some time for myself. Appreciate all the help in keeping me going. Thanks mentors!

Osanbob
 

pgerts

Old age member
Mentor
#16
Old servos are just fine with the DX8.
There could possibly be an issue with some receivers.
Normal older receivers are fine and you dont have to worry at all.
Some high end receivers are copatible with faster new digital servos and you might need to look in the manual how to setup your Tx-Rx combination to be in the "slow mode".

WE WANT PICTURES! of the transformation.
 

Ak Flyer

Fly the wings off
Mentor
#17
It is a plug and play with the receiver and the DX8 will work perfectly. You do need to make sure that you are sending a regulated power source to the receiver/servos. If your esc has a bec then you are okay, as long as it will provide enough amperage to drive all the servos in your trainer. If it doesn't or it has a low amp bec then you will still need the extra battery for the radio gear like it had before. I would also make sure it is a 4.8 or 5 volt bec as some older servos don't like 6 volts. Look up your servos and see if they have a 6.0 volt rating.
 

pgerts

Old age member
Mentor
#18
.. I would also make sure it is a 4.8 or 5 volt bec as some older servos don't like 6 volts. Look up your servos and see if they have a 6.0 volt rating.
Have you had any problems?
I am a bit lazy and forget to charge my Nixx when i am going to fly my old glow planes.
I have been using my indoor 2 cell lipo directly to my spectrum and orange rx the last 2 years with older Hitec, Futaba, MPX and China servos without any problems. I have not seen any "normal" servos that wont run on 5 cell nixx and the voltage for a nixx directly from the charger might be 1,6 volt * 5 gives 8 volts almost same as 2 cell Lipo.
 

Ak Flyer

Fly the wings off
Mentor
#19
Have you had any problems?
I am a bit lazy and forget to charge my Nixx when i am going to fly my old glow planes.
I have been using my indoor 2 cell lipo directly to my spectrum and orange rx the last 2 years with older Hitec, Futaba, MPX and China servos without any problems. I have not seen any "normal" servos that wont run on 5 cell nixx and the voltage for a nixx directly from the charger might be 1,6 volt * 5 gives 8 volts almost same as 2 cell Lipo.
I run all my nitros on 6V NiMh 2000 packs. I haven't run into any problems, but I talked to enough guys who have had servos lock up to put the fear in me. I would sure hate to lose a plane to that, know what I mean? I shattered my four star and it's taken so long to find time to repair it that I'm not wanting to take chances.
 

FlyingMonkey

Stuck in Sunny FL
Staff member
Admin
#20
Thanks for the help. I am taking all the notes down. I found a program today that helps and it is backing up the equations you are teaching me its called motocalc. Not sure how good it really is but it is matching what you are saying about motor size, batterys and ESC. You guys probably dont need this becuase you already know this stuff by heart.
By heart? Not likely... not me at least. I use any and all tools available. Usually you pick the motor for the plane, then you pick the battery and speed control for the motor. Most places selling the motor, will list the specs, and often recommend the accessories needed to go with it.