Wattflyer RC Network: RC Universe :: RCU Magazine :: RCU Forums :: RCU Classifieds :: RCU User Reviews :: RCU YouTube
Home Who's Online Calendar Today's Posts RealTime Post Spy Mark Forums Read
Go Back   WattFlyer RC Electric Flight Forums - Discuss radio control eflight > Electric R/C Airplanes > Beginners
Register Members List Wattflyer Extras Articles Search Today's Posts Mark Forums Read Social Groups

Beginners New to e-power flying? Get the low down in here from experienced e-power RC pilots!

Thank you for your support (hide ads)
Reply
 
Thread Tools Display Modes
Old 11-05-2018, 04:09 PM   #1
aquavit
New Member
 
Join Date: Nov 2018
Location: UK & Hungary
Posts: 1
Thanked 0 Times in 0 Posts
iTrader: (0)
Friends: (0)
Default Returnee to EF with a lot of questions

I was a regular flyer around thirty years ago, mainly slope soaring but graduated to electric flight as the hobby first started to establish itself. Other aspects of my life took over and I fell out of the habit, but retained most of my airframes and electronics. I am now wanting to re-start the hobby and would like to utilise what I have wherever possible. I understand that things have moved on a lot since I last flew so would like some advice on what I can hope to achieve.

First off, my transmitter set-up looks to be outmoded, I have a JRX347, which of course is 35Mghz, on firing it up I discovered that it is not responding with control surfaces juddering and no answer to my control commands. I therefore intend to replace this, probably with a Hitec Flash7 combo as I have a fair few Hitec and JR micro servos that I'm guessing I could still utilise.

The bigger issues though surround my airframes and the batteries/motors and ESC's that I have. It seems Ni-Cads are now out of fashion!

Airframe No.1 is a Graupner Cherry ii which I flew extensively before my sabbatical from the hobby. I would like to get this airborne again as my first step to flying rehab. It's powered by a Graupner Speed 700 BB Turbo (I think) 9.6V through a "Mini Switch 40" speed controller and 10 cell NiCad pack. Ideally I would like to keep everything in the airframe and just swap out the battery pack for the latest tech.

Airframe No. 2 is a Multiplex TwinStar, also extensively flown, powered by 7 cells and has a Picos micro Rx/ESC. Again, ideally just swap the battery pack.

Airframe No. 3 is a part built Graupner Match which I would like to complete and get airborne. The motor is a Graupner Speed 500 BB Race VS, ESC 7.2V, ESC is a Jeti JES 350 Eco - this is marked "6 - 12 cells NiCd" but can I assume any type of battery would be ok with it?

To summarise, it seems I need to upgrade my radio gear, replace obsolete NiCad's with newer battery technology and acquire a suitable charger for these (would prefer an AC/DC dual charger). I'm hoping I can utilise my existing ESC's and servos so advice on which is the best way forward would be greatly appreciated.
aquavit is offline  
  Reply With Quote
Old 11-05-2018, 11:57 PM   #2
quorneng
Super Contributor
 
quorneng's Avatar
 
Join Date: Jul 2008
Location: Cheshire, UK
Posts: 1,783
Thanked 87 Times in 83 Posts
Club: A lone flyer!
Awards Showcase

Scratchbuilders Award  Scratchbuilders Award 
iTrader: (0)
Friends: (6)
Default

aquavit
Note A 10 cell NiCd is a nominal 12V but I assume the 700BB turbo is ok with that.
A 3c LiPo (11.1 nominal) would be a reasonable replacement. The slightly lower nominal voltage should not be much of a problem as LiPo maintain their voltage better under load.
LiPo have about twice the power density of a NiCd so it will have twice at least twice the capacity for the same weight or any combination down to 1/2 the weight for the same capacity!
If everything else still works it would be just a simply battery swap but be aware the old brushed speed controller won't necessarily be correctly set to cut power to the motor to protect the LiPo. Discharging a LiPo below 3V per cell under load will seriously damage it.

A 2s LiPo is almost a direct swap for a 7 cell Nicd so the same things would apply.

The logical conclusion is to go the 'whole hog' and use a brushless motor and ESC. Brushless motors are considerably lighter and more efficient too.

Just as a guide I too went from brushed speed 480 and 7 cell NiCd to a brushless motor and 3s LiPo. Only 1/2 the motor battery weight yet with 1/3 more battery capacity and more full power thrust giving the plane a significantly better thrust to weight ratio. Easy aerobatics and the effective flight duration rose from 5 min max to 10 min plus.
A "no brainer" really.
quorneng is offline  
  Reply With Quote
Old 11-06-2018, 12:38 AM   #3
Don Sims
Administrator
 
Don Sims's Avatar
 
Join Date: Sep 2005
Location: Middle Tennessee
Posts: 12,060
View Don Sims's Gallery114
Thanked 412 Times in 401 Posts
Awards Showcase

WAA-08 Pilot  Globetrotter Pilot 
iTrader: (3)
Friends: (40)
Default

Welcome back.

Take care and thanks for posting at WattFlyer!!

Don
Don Sims is online now  
  Reply With Quote
Old 11-06-2018, 02:11 AM   #4
Stick Dude
Member
 
Stick Dude's Avatar
 
Join Date: Oct 2018
Location: Dfw Texas
Posts: 153
Thanked 4 Times in 4 Posts
Club: Ill try to become a member of a local rc club...
iTrader: (0)
Friends: (1)
Default

Im new for e flight, I learned on my foamy, and actually succeeded! Only thing that spooks me is the lipo batteries, I heard horror stories about burnt down houses during charging? and explosions? So I will need to research those nasty little thing thoroughly!
Stick Dude is offline  
  Reply With Quote
Old 11-10-2018, 12:13 AM   #5
AEAJR
Community Moderator
 
Join Date: Aug 2005
Location: NY, USA
Posts: 5,781
Thanked 394 Times in 353 Posts
Club: Long Island Silent Flyers
Awards Showcase

WAA-08 Pilot  Outstanding Contributor Award 
iTrader: (0)
Friends: (10)
Talking

Originally Posted by aquavit View Post
I was a regular flyer around thirty years ago, mainly slope soaring but graduated to electric flight as the hobby first started to establish itself. Other aspects of my life took over and I fell out of the habit, but retained most of my airframes and electronics. I am now wanting to re-start the hobby and would like to utilise what I have wherever possible. I understand that things have moved on a lot since I last flew so would like some advice on what I can hope to achieve.

First off, my transmitter set-up looks to be outmoded, I have a JRX347, which of course is 35Mghz, on firing it up I discovered that it is not responding with control surfaces juddering and no answer to my control commands. I therefore intend to replace this, probably with a Hitec Flash7 combo as I have a fair few Hitec and JR micro servos that I'm guessing I could still utilise.

The bigger issues though surround my airframes and the batteries/motors and ESC's that I have. It seems Ni-Cads are now out of fashion!

Snip...

To summarise, it seems I need to upgrade my radio gear, replace obsolete NiCad's with newer battery technology and acquire a suitable charger for these (would prefer an AC/DC dual charger). I'm hoping I can utilise my existing ESC's and servos so advice on which is the best way forward would be greatly appreciated.
Welcome back to flying.

I too was an active slope soaring pilot. Have not flown that much recently. Most I fly electric launched gliders and pure gliders with a mixing in of small electric airplanes. But thermal soaring is my main passion.


35 MHz? You must be in the UK. No one flew 35 in the USA.

2.4 GHz is pretty much the standard today. No more frequency control issues and the receivers are tiny.

If I recall right, the Hitec Flash 7 is a module based radio. You can update it with a 2.4 GHz module if you wish. Then you can change over over time as you switch back and forth between 35 and 2.4. I do that with my Futaba 9C Super.

All of my active planes are on 2.4 GHz but I still have some on 72 MHz. I still have two 72 MHz channel modules for these radios.

If you want to learn about electric flight I would suggest you visit here:

EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC POWERED FLIGHT
www.wattflyer.com/forums/showthread.php?t=31368

A 3 cell lipo pack is nominally 11.1V but it 12.6V at full charge. About 4X the energy density of NiCd. So the little bit of voltage you give up on the 3 Cell pack you more than make up in weight savings.

One thing to note about LiPo batteries is that they don't like to be run down too far. If you get down to under 3V per cell, resting voltage, they can become problematic. And if you get them below 2.5V they will start taking damage. If you run a LiPo pack down to zero, like we used to do with the NiCd packs, you can probably throw that LiPo pack away.

Where the old BEC and low voltage control part of the ESC was there to insure that there was enough power to run the receiver and servos, it now serves a larger purpose of making sure we don't run the batteries too low so we don't damage them.


Just keep asking questions.

Read the book at the link.

We will be glad to help.

Long Island Silent Flyers
www.lisf.org
Eastern Soaring League
www.flyesl.org
AEAJR is offline  
  Reply With Quote
Old 11-10-2018, 12:24 AM   #6
Jack_Hammer
Member
 
Join Date: Oct 2018
Posts: 23
Thanked 1 Time in 1 Post
iTrader: (0)
Friends: (0)
Default

[QUOTE=Stick Dude;1015570]Im new for e flight, I learned on my foamy, and actually succeeded! Only thing that spooks me is the lipo batteries, I heard horror stories about burnt down houses during charging? and explosions? So I will need to research those nasty little thing thoroughly![/QUOTE

Kinda silly to give such credence over something that happens less than. 000000001% of the time; and of that 00000001%, its usually stupids fault. After all I've never heard of an Amazon, Hobby King, freighter or UPS truck burning up in a freak lipo fire.

I've dropped lipos, crashed em and dented em, none of which have ever caught fire. I've had one puff up after a bad crash and dent. Threw it in the bucket of water for a day or two (outside) then disposed of it.

Follow the standard charging, operation and safety procedures and you'll be fine. You're not playing with nitroglycerin.
Jack_Hammer is offline  
  Reply With Quote
Old 11-10-2018, 12:30 AM   #7
AEAJR
Community Moderator
 
Join Date: Aug 2005
Location: NY, USA
Posts: 5,781
Thanked 394 Times in 353 Posts
Club: Long Island Silent Flyers
Awards Showcase

WAA-08 Pilot  Outstanding Contributor Award 
iTrader: (0)
Friends: (10)
Talking

Originally Posted by aquavit View Post

snip...

Airframe No.1 is a Graupner Cherry ii which I flew extensively before my sabbatical from the hobby. I would like to get this airborne again as my first step to flying rehab. It's powered by a Graupner Speed 700 BB Turbo (I think) 9.6V through a "Mini Switch 40" speed controller and 10 cell NiCad pack. Ideally I would like to keep everything in the airframe and just swap out the battery pack for the latest tech.
10 Cell NiCd is 12V. You can replace that with a 3 Cell lipo. Probably something around 3000 mAH would be appropriate size. 30C or better would be my recommendation.

The motor should take that fine but I don't know anything about the Mini Swit ch 40 Speed controller.

Before you start swapping ESC and stuff, tell me the wing span, weight (without the NiCd) and they type of performance you expect. I don't know that plane.

Finding an ESC to run a Speed 700 might be a problem as that stuff is not used much anymore. I don't even know if they make large ESC for brushed motors anymore. Motors are pretty much all brushless now. Smaller, lighter and much more powerful than a Speed 700.


Originally Posted by aquavit View Post
Airframe No. 2 is a Multiplex TwinStar, also extensively flown, powered by 7 cells and has a Picos micro Rx/ESC. Again, ideally just swap the battery pack.
7 Cell is 8.4V. you can replace that with a 2 cell 7.4 V pack. Again the drop and voltage should be covered by the reduce weight. What was the capacity of that 7 cell pack. I would go for a lipo with 2X to 3X the capacity of the NiCd pack.


Originally Posted by aquavit View Post
Airframe No. 3 is a part built Graupner Match which I would like to complete and get airborne. The motor is a Graupner Speed 500 BB Race VS, ESC 7.2V, ESC is a Jeti JES 350 Eco - this is marked "6 - 12 cells NiCd" but can I assume any type of battery would be ok with it?

snip ...
Don't know that plane. I would stop the build and convert to modern components Again, I don't know the plane so wing span and all up weight, without the NiCd would give a starting point for the new power system. Also what type of performance you would want. Gentle Flyer? Sport plane? All out competition aerobat?

Read the chapter on sizing your power system. I would recommend a minimum of 75 watts per pound with sport planes and more typically we would power them at 100 watts/pound or higher.

Even my gliders are over 100 watts per pound for fast climb to soaring height.

At around 130 watts/pound they can climb straight up!

At around 175 watts/pound you can hover the plane on the prop.

Today's brushless motors are 2 to 3X as efficient as the brushed motors and they do it at 1/2 the weight.


Again, look through the book I suggested on Wattflyer.

Long Island Silent Flyers
www.lisf.org
Eastern Soaring League
www.flyesl.org
AEAJR is offline  
  Reply With Quote
Old 11-10-2018, 10:15 AM   #8
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 11,662
View solentlife's Gallery47
Thanked 565 Times in 555 Posts
Club: Founder Member Ventspils RC Club. Ex Waltham Chase and Meon Valley Soaring.
Awards Showcase

Scratchbuilders Award  Scratchbuilders Award  Outstanding Contributor Award  125mph Speed Demon 
iTrader: (0)
Friends: (19)
Default

Above replies have good info ...

My view ? Brushed motors are OK - but given that Brushless motors are far superior and brands such as RCTimer and Turnigy are so cheap ... worth swapping over ...
But of course then the ESC has to be changed as well to power a Brushless.
LiPo batterys as well and you have power systems that make literally anything you can throw in the air fly !!

I would suggest a scroll through sites such as Hobby King ... MotionRC ... RCTimer etc.

As regards radio ? The choice of radios today is huge. Budget full action radios from $50 up to whatever you want to pay.

I was a JR fanatic and on return to the hobby bought 9x radio ... used my old JR servos but soon understood that those top line servos from the 80's were very slow compared to even the cheapest today. RX's from those days were huge compared to todays ... and prices ? I can now buy a bagful of good servos for same money I paid for one servo of the 80's.

I really do advise going through sites online and see what is available today. Look at models similar in size and see what set-ups they use ... It is pretty certain that you will change over to modern gear .... part by part or even a full model at a time ?

AND Wattflyer is the place to be to help ..

Nigel

222kph PKJ,EDF Concorde, Mini4,Mig3,T45,PKJ twin,ME109,Edge540,Cessna182,Skymaster Biplane,F15,F16,Badius,Ultimate,SE5,Qbee10,450 Heli,V911,J3 Cub Founder 9x forum: http://groups.yahoo.com/group/Flysky_RC_radio/
- Subscribe my Youtube: "solentlifeuk"
solentlife is offline  
  Reply With Quote
Reply

  WattFlyer RC Electric Flight Forums - Discuss radio control eflight > Electric R/C Airplanes > Beginners


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Glue Questions dereckbc General Electric Discussions 14 03-01-2017 08:35 AM
First flight with the new Dx6 - Questions woodmangler Beginners 10 07-25-2015 10:50 PM
A few questions about a possible project maxmwill Scratch and Kit Built Aircraft 6 06-27-2015 10:04 PM
HITEC customer sevice is very good,very helpful to talk to asking questions. tobydogs RC Radios, Transmitters, Receivers, Servos, gyros 2 10-02-2013 01:44 AM
Newbie With Questions......Sorry!! SNIPERWOLF Beginners 10 01-25-2011 01:56 AM


All times are GMT +1. The time now is 01:50 AM.


Powered by: vBulletin
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Copyright 2005 WattfFlyer.com
RCU Eflight HQ

Charities we support Select: Yorkie Rescue  ::  Crohn's & Colitis Foundation



Page generated in 0.09712 seconds with 33 queries