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 > Scratch and Kit Built Aircraft
Register Members List Wattflyer Extras Articles Search Today's Posts Mark Forums Read Social Groups

Scratch and Kit Built Aircraft Discuss and share your scratch built or kit built aircraft as well as building techniques, methods, mediums and resources.

Thank you for your support (hide ads)
Reply
 
Thread Tools Display Modes
Old 01-04-2014, 11:04 PM   #1
tobydogs
love to build!
 
tobydogs's Avatar
 
Join Date: Jan 2010
Location: nj usa
Posts: 2,844
Thanked 197 Times in 194 Posts
Club: rcrcc rockland county,ny
Awards Showcase

Outstanding Contributor Award 
iTrader: (0)
Friends: (13)
Default glow to electric weight gain,how much extra weight is too much?

hello builders of conversions,

so i placed everything into my rv 4-40 using the 4000mah 40c[a 3cell & 4cell]7cell count batteries and am shocked at how nose heavy these packs make this RV over the last RV 4-40 i built using 2 3cell 4000mah 20c packs to get 6cell. and a feather weight turnigy esc.

i also think the eflight power 60,and 100amp castle esc weighs a lot more than my cheaper hobbyking setup that failed and caused the fatal crash.

now i may have to scrap the location of the batteries that were easily accessible via a hatch in the cowls underside. if i leave them as is i will need to locate the esc at least 16" away from where i plug in the battery which is unacceptable,and the 3 esc to motor wires would also be 16inchs which would be ok. the Rx battery pack would get pushed to the tail area and basically out of reach except by a custom little hatch built in the tail section.

...........oh yeah,i forgot the reason for this post.the question is
so whats the weight gain others have added to their conversions?
.................................................. .................................................. ...
i really don't want to buy more batteries of lesser weight/mah/c rating,so right now I'm looking at relocating the batteries to be installed when the wing is off,change the rx battery out for either using the bec in the castle which i don't want cutting power to the motor if theres ever lvc ,or get a ubec like the castle 10 amp/6v. having to rework everything is annoying since i was building and figuring my design based on the previous RV-4 which i never weighed after completion and gain cg with everything pushed forward.
i would even consider moving the tail servos to the rear of the fuse and ditch the extra weight of those push rods.

sorry for the rambling i just need to go back and re-figure this bird a little.

narrow is the place to land...wide is the space to crash....choose the narrow way!
tobydogs is offline  
  Reply With Quote
Old 01-04-2014, 11:32 PM   #2
fhhuber
Super Contributor
 
fhhuber's Avatar
 
Join Date: Mar 2013
Posts: 1,550
Thanked 166 Times in 158 Posts
iTrader: (0)
Friends: (1)
Default

Currently you can actually come out lighter with electric than glow, gaining power and performance at a modest (possibly none) loss of duration.

It requires a bit of work lightening the parts of the struture designed to deal with the cyclic stresses imposed by the internal combustion engine, but its not hard once you know what to do.
fhhuber is online now  
  Reply With Quote
Old 01-05-2014, 12:04 AM   #3
JetPlaneFlyer
Super Contributor
 
Join Date: Mar 2009
Location: Aberdeen, Scotland
Posts: 3,979
Thanked 454 Times in 422 Posts
Awards Showcase

5kW  Outstanding Contributor Award  1kW 
iTrader: (0)
Friends: (7)
Default

I think you have way, wayyy too much battery and motor for a model of that size.

The 4-40 was intended for a 40-52 glow motor. The Power 60 is a 60 size (1700W) electric.. so far too big and heavy. A 800-900W power system would be tons of power along with something like a 5s battery in the 2600-3000mAh range.

I'm a great believer that you can never have too much power, but you certainly can have too much weight. You need a much lighter power system. You can move stuff around as much as you like but that wont make it lighter.
JetPlaneFlyer is offline  
  Reply With Quote
Old 01-05-2014, 01:18 AM   #4
Larry3215
Look out for that tree!!!
 
Larry3215's Avatar
 
Join Date: Mar 2006
Location: Gig Harbor, Wa USA
Posts: 6,714
View Larry3215's Gallery63
Thanked 688 Times in 667 Posts
Club: Kitsap ARCS & E-FLAPS
Awards Showcase

90 Minute Thermal Duration  60 Minute Thermal Duration  30 Minute Thermal Duration  4kW 
iTrader: (6)
Friends: (21)
Default

Originally Posted by JetPlaneFlyer View Post
I think you have way, wayyy too much battery and motor for a model of that size.

The 4-40 was intended for a 40-52 glow motor. The Power 60 is a 60 size (1700W) electric.. so far too big and heavy. A 800-900W power system would be tons of power along with something like a 5s battery in the 2600-3000mAh range.

I'm a great believer that you can never have too much power, but you certainly can have too much weight. You need a much lighter power system. You can move stuff around as much as you like but that wont make it lighter.
+100

Sorry

I think I need a signature.
Larry
Larry3215 is offline  
  Reply With Quote
Old 01-05-2014, 02:48 AM   #5
kyleservicetech
Dennis V
 
kyleservicetech's Avatar
 
Join Date: Apr 2008
Location: Wisconsin, USA
Posts: 7,357
Thanked 654 Times in 637 Posts
Club: www.racinercclub.com (I'm the newsletter editor)
Awards Showcase

Outstanding Contributor Award  3kW  2kW  100mph Speed Demon 
iTrader: (1)
Friends: (18)
Default

Originally Posted by tobydogs View Post
hello builders of conversions,

so i placed everything into my rv 4-40 using the 4000mah 40c[a 3cell & 4cell]7cell count batteries and am shocked at how nose heavy these packs make this RV over the last RV 4-40 i built using 2 3cell 4000mah 20c packs to get 6cell. and a feather weight turnigy esc.

i also think the eflight power 60,and 100amp castle esc weighs a lot more than my cheaper hobbyking setup that failed and caused the fatal crash.

now i may have to scrap the location of the batteries that were easily accessible via a hatch in the cowls underside. if i leave them as is i will need to locate the esc at least 16" away from where i plug in the battery which is unacceptable,and the 3 esc to motor wires would also be 16inchs which would be ok. the Rx battery pack would get pushed to the tail area and basically out of reach except by a custom little hatch built in the tail section.

...........oh yeah,i forgot the reason for this post.the question is
so whats the weight gain others have added to their conversions?
.................................................. .................................................. ...
i really don't want to buy more batteries of lesser weight/mah/c rating,so right now I'm looking at relocating the batteries to be installed when the wing is off,change the rx battery out for either using the bec in the castle which i don't want cutting power to the motor if theres ever lvc ,or get a ubec like the castle 10 amp/6v. having to rework everything is annoying since i was building and figuring my design based on the previous RV-4 which i never weighed after completion and gain cg with everything pushed forward.
i would even consider moving the tail servos to the rear of the fuse and ditch the extra weight of those push rods.

sorry for the rambling i just need to go back and re-figure this bird a little.
Properly setup, these electric power systems can easily match the power output and performance of a glow engine in the same model. Only, you've got shorter flying times. This model looks to weigh in at about 6 pounds or so. For good acrobatic performance, you'd need about 140 watts per pound of airplane, or about 800 Watts. Figuring about 60 amps on the motor, that translates to Power equals Volts Times Amp, or Volts equals Power/Amps. So at 800 Watts, that comes out to be 800/60 or about 13 Volts. That is a 4S LiPo territory. Running your battery pack at perhaps 15C, you'd need a battery of about 3000-4000 Mah, 4S LiPo.

I'm running those heavier, physically larger, lower voltage A123 cells in all of my models. Nice thing about these A123's, they do not have a fire hazard, and can be permanently installed in your model. They can be be recharged repeatedly in 15 minutes with a high powered charger. After 300 or 400 flights, they don't loose very much capacity. (I've got over 100 of them in my various models.)

"C" and what it is
http://www.wattflyer.com/forums/showthread.php?t=65869

Here's some more info on this subject.

Thread on 70 size glow engine conversion to electric
http://www.wattflyer.com/forums/showthread.php?t=45222

Hacker 6S2P A123 powered Models
http://www.wattflyer.com/forums/showthread.php?t=44686

Hangar 9 Kantana Model
http://www.wattflyer.com/forums/showthread.php?t=68844

Hanger 9 Twist 40 Model
http://www.wattflyer.com/forums/showthread.php?t=70548

AEAJR's Site on Electric Power
http://www.wattflyer.com/forums/showthread.php?t=18521

BEC Linear Current Rating
http://www.wattflyer.com/forums/showthread.php?t=63779

DennyV
Retired and the days are just too short, busier than ever!
kyleservicetech is offline  
  Reply With Quote
Old 01-05-2014, 03:15 AM   #6
Larry3215
Look out for that tree!!!
 
Larry3215's Avatar
 
Join Date: Mar 2006
Location: Gig Harbor, Wa USA
Posts: 6,714
View Larry3215's Gallery63
Thanked 688 Times in 667 Posts
Club: Kitsap ARCS & E-FLAPS
Awards Showcase

90 Minute Thermal Duration  60 Minute Thermal Duration  30 Minute Thermal Duration  4kW 
iTrader: (6)
Friends: (21)
Default

Forgot to answer your main question - every gas/glow to electric conversion I have done has come out lighter than the original design weight.

Here are a few ARF's Ive done that I have pics of. All came in under the normal gas/glow build weight - mostly due to savings in the power system. All had at least as good performance as the gas/glow originals.

Your power system weighs almost as much as my heaviest one - which was good for around 3000 watts and powered an 17 pound model!








Attached Thumbnails
Click image for larger version

Name:	standing(Large).JPG
Views:	124
Size:	119.1 KB
ID:	172762 Great Planes Ultimate 160
Click image for larger version

Name:	IMG_0236 (Medium).JPG
Views:	130
Size:	78.9 KB
ID:	172764 an old 89" span Super Cub
Click image for larger version

Name:	IMG_4438 (Medium).JPG
Views:	128
Size:	87.0 KB
ID:	172765 50cc 87" span KMP Yak

I think I need a signature.
Larry
Larry3215 is offline  
  Reply With Quote
Old 01-05-2014, 04:04 AM   #7
tobydogs
love to build!
 
tobydogs's Avatar
 
Join Date: Jan 2010
Location: nj usa
Posts: 2,844
Thanked 197 Times in 194 Posts
Club: rcrcc rockland county,ny
Awards Showcase

Outstanding Contributor Award 
iTrader: (0)
Friends: (13)
Default

gang,
i do believe you've talked some sénce into me.... i will research a lesser size motor with higher kv and use the 4cell 4000mah 40c battery alone cutting out the 3cell. this will allow me to use the battery box i built and possibly get a smaller esc.

today is my birthday,so might just as well use the money for the RV-4.

what eflight motor to buy and esc....i really do want vertical to be impressive. what set up will attain my goal and not break the bank. the power 60 on 7cells packs a huge punch in the greatplanes extra 300s at 64" wingspan.she really tears up the sky with no hurting handling and i know it weighs more than its glow equal since a bud at my field has one.he was very impressed with the power from electric as were other watching

the same goes for the hog bipe from sig....and it defiantly flys like a pig with added weight compared to another bud at the field who flys his pig with glow.

ill look into some choices and post back Sunday . have a great night and thanks for the input. stu

narrow is the place to land...wide is the space to crash....choose the narrow way!
tobydogs is offline  
  Reply With Quote
Old 01-05-2014, 04:23 AM   #8
fhhuber
Super Contributor
 
fhhuber's Avatar
 
Join Date: Mar 2013
Posts: 1,550
Thanked 166 Times in 158 Posts
iTrader: (0)
Friends: (1)
Default

Its a 40 size model... Power 32 will fly it for scale performance. Power 46 will fly it very well.
fhhuber is online now  
  Reply With Quote
Old 01-05-2014, 05:15 AM   #9
Larry3215
Look out for that tree!!!
 
Larry3215's Avatar
 
Join Date: Mar 2006
Location: Gig Harbor, Wa USA
Posts: 6,714
View Larry3215's Gallery63
Thanked 688 Times in 667 Posts
Club: Kitsap ARCS & E-FLAPS
Awards Showcase

90 Minute Thermal Duration  60 Minute Thermal Duration  30 Minute Thermal Duration  4kW 
iTrader: (6)
Friends: (21)
Default

Happy party/plane day!!

I think I need a signature.
Larry
Larry3215 is offline  
  Reply With Quote
Old 01-05-2014, 05:22 AM   #10
CHELLIE
Super Contributor
 
CHELLIE's Avatar
 
Join Date: Oct 2006
Location: Hesperia, So. Calif
Posts: 17,980
View CHELLIE's Gallery13
Thanked 2,072 Times in 1,983 Posts
Club: Chino Renegades RC Flying Club
Awards Showcase

Scratchbuilders Award  Scratchbuilders Award  Ambassador Award  100mph Speed Demon 
iTrader: (4)
Friends: (304)
Default

The power 32 motor will work great on 5 cells, you need to use 5 cells because its a low 770KV motor, a 12x6 11x7 or 9x9 prop will make it Haul @@s a 60 to 80 amp esc will work great, I dont think you need more than a 4000mah lipo. but to keep the weight down, I think I would use 3000mah lipos.

http://www.hobbyking.com/hobbyking/s...ontroller.html

http://www.hobbyking.com/hobbyking/s...ontroller.html

I may be getting Older, But I Refuse to grow Up I am Having to much Fun to Grow Up LOL
CHELLIE is offline  
  Reply With Quote
Old 01-05-2014, 05:32 AM   #11
CHELLIE
Super Contributor
 
CHELLIE's Avatar
 
Join Date: Oct 2006
Location: Hesperia, So. Calif
Posts: 17,980
View CHELLIE's Gallery13
Thanked 2,072 Times in 1,983 Posts
Club: Chino Renegades RC Flying Club
Awards Showcase

Scratchbuilders Award  Scratchbuilders Award  Ambassador Award  100mph Speed Demon 
iTrader: (4)
Friends: (304)
Default


power 32 motor on 5 cell lipo and a 9x9 prop

I may be getting Older, But I Refuse to grow Up I am Having to much Fun to Grow Up LOL
CHELLIE is offline  
  Reply With Quote
Old 01-05-2014, 06:22 AM   #12
tobydogs
love to build!
 
tobydogs's Avatar
 
Join Date: Jan 2010
Location: nj usa
Posts: 2,844
Thanked 197 Times in 194 Posts
Club: rcrcc rockland county,ny
Awards Showcase

Outstanding Contributor Award 
iTrader: (0)
Friends: (13)
Default

the weight of the RV by greatplanes is 5.5 to 6.5 pounds. i fear all up weight with the batteries will be 7+pounds.

research is showing the eflite power46 on 5cells would use a smaller prop than the 4cell option. seeing as the rv rolls very close to the ground ,the 14"prop is out. in fact a 12"apc e prop will be perfect. greatplanes says 11x6prop.

the motor weighs less and may be moved closer to the firewall, the esc can be a 80amp or still the castle moved forward inside the fuse. best of all the battery box will have space for cool air flow over the packs.

eflite power 46=$89, the 2cell 4000m 40c zippies to go with my 3cell 4000m 40c bats gives me 5cells,i'll need 4 of the at $20 each[that includes shipping]. this reduces the nose weight by 2 cells.and the motor will be lighter.

its late here,1:16am...i'll shift things around after church.

narrow is the place to land...wide is the space to crash....choose the narrow way!
tobydogs is offline  
  Reply With Quote
Old 01-05-2014, 07:40 AM   #13
solentlife
Super Contributor
 
solentlife's Avatar
 
Join Date: Oct 2010
Location: Ex UK Brit now in Latvia west coast - Ventspils
Posts: 5,023
View solentlife's Gallery47
Thanked 208 Times in 205 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: (8)
Default

My conversions albeit in the smaller sizes - have all been lighter than the original glow ... plus the advantage that I could move weight around better than when glow. Major weights then were engine, Rx battery and Fuel tank. The only part then that could be moved significantly was the Rx battery.

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 online now  
  Reply With Quote
Old 01-05-2014, 01:02 PM   #14
tobydogs
love to build!
 
tobydogs's Avatar
 
Join Date: Jan 2010
Location: nj usa
Posts: 2,844
Thanked 197 Times in 194 Posts
Club: rcrcc rockland county,ny
Awards Showcase

Outstanding Contributor Award 
iTrader: (0)
Friends: (13)
Default

i agree Nigel,my smalled 1/2a builds were all no gain as the smaller brushless motor automatically cut weight,and smaller battery made for easy balancing.

YIKES!!! chellie,you are a sweetheart to supply that video of the sundowner. i just watched it and ws amazed at its speed. i the checked out the spec's on the sundowner...60+wingspan and up to 7lb's flight weight.when i get home from Church the first order of business will be to order a new motor and a couple of 2 cell 4000mah 40c batteries to mate with my already existing 3cell pack to get five cells.I'm also considering using the turnigy 80 amp plush. they are in several planes and have been great to my birds like the towerhobbies uproar.

lastly,i am considering the power 60 and 100 cc esc for the wall queen f4u corsair,64 inch wingspan and weighs what a topflight fully sheeted kit would way...heavy!


Attached Thumbnails
Click image for larger version

Name:	march 130.jpg
Views:	21
Size:	145.9 KB
ID:	172766

narrow is the place to land...wide is the space to crash....choose the narrow way!
tobydogs is offline  
  Reply With Quote
Old 01-06-2014, 01:39 AM   #15
tobydogs
love to build!
 
tobydogs's Avatar
 
Join Date: Jan 2010
Location: nj usa
Posts: 2,844
Thanked 197 Times in 194 Posts
Club: rcrcc rockland county,ny
Awards Showcase

Outstanding Contributor Award 
iTrader: (0)
Friends: (13)
Default

i know absolutely 0 about glow motors and the weight of fuel. so if i could ask another question please. these are the spec's on the RV 4-40....when the manufacturer of kits give a 1/2 pound to play with does that include all up weight with fuel. i kind of wonder since fuel tanks come in different sizes and liquid isn't light. a guess is approx 770grams. motor with 10 0z filled tank

to go electric with all operating items like motor,rx,rx battery...ect...ect...it really adds up quick.

the added total weight of batteries,and speed control/motor=952grams[2 lb's]. this is on 5 cell 4000mah40c batteries using a power 46 eflite motor. i could use the built in bec with the castle esc since i trust it to work 4 servos and rx flawlessly.i', using the cc esc to eliminate the 147g rx battery.

total weight of RV-40 using the 7cell pack and the 60power motor.....way to much...lol. same as aboves list and the total is 1168g[2.5 lb's]

this why i asked the question.....it weighs a ton and i wonder how everyone else is coming in under spec weight of a build. stu



SPECIFICATIONS
Stock Number: GPMA0180
Wingspan: 54.65 in (1388 mm)
Wing Area: 631.6 in² (40.8 dm²)
Weight: 5.75-6.25 lb (2.6-2.8 kg)
Wing Loading: 20.9-22.8 oz/ft² (64.1-69.7 g/dm²)
Fuselage Length: 49.6 in (1260 mm)
Required: 2-stroke .40-.52 cu in engine or 4-stroke .48-.70 cu in (8.0-11.5 cu in); also required, 4-5 channel Radio with 5-7 servos (5-channel radio with 7 servos required to use optional flaps) Pilot figure not included.
Recommended: Pitts style muffler
Product Manual - Parts Listing - Accessories Needed

narrow is the place to land...wide is the space to crash....choose the narrow way!
tobydogs is offline  
  Reply With Quote
Old 01-06-2014, 03:08 AM   #16
kyleservicetech
Dennis V
 
kyleservicetech's Avatar
 
Join Date: Apr 2008
Location: Wisconsin, USA
Posts: 7,357
Thanked 654 Times in 637 Posts
Club: www.racinercclub.com (I'm the newsletter editor)
Awards Showcase

Outstanding Contributor Award  3kW  2kW  100mph Speed Demon 
iTrader: (1)
Friends: (18)
Default

Originally Posted by tobydogs View Post
i know absolutely 0 about glow motors and the weight of fuel. so if i could ask another question please. these are the spec's on the RV 4-40....when the manufacturer of kits give a 1/2 pound to play with does that include all up weight with fuel. i kind of wonder since fuel tanks come in different sizes and liquid isn't light. a guess is approx 770grams. motor with 10 0z filled tank

to go electric with all operating items like motor,rx,rx battery...ect...ect...it really adds up quick.

the added total weight of batteries,and speed control/motor=952grams[2 lb's]. this is on 5 cell 4000mah40c batteries using a power 46 eflite motor. i could use the built in bec with the castle esc since i trust it to work 4 servos and rx flawlessly.i', using the cc esc to eliminate the 147g rx battery.

total weight of RV-40 using the 7cell pack and the 60power motor.....way to much...lol. same as aboves list and the total is 1168g[2.5 lb's]

this why i asked the question.....it weighs a ton and i wonder how everyone else is coming in under spec weight of a build. stu



SPECIFICATIONS
Stock Number: GPMA0180
Wingspan: 54.65 in (1388 mm)
Wing Area: 631.6 in² (40.8 dm²)
Weight: 5.75-6.25 lb (2.6-2.8 kg)
Wing Loading: 20.9-22.8 oz/ft² (64.1-69.7 g/dm²)
Fuselage Length: 49.6 in (1260 mm)
Required: 2-stroke .40-.52 cu in engine or 4-stroke .48-.70 cu in (8.0-11.5 cu in); also required, 4-5 channel Radio with 5-7 servos (5-channel radio with 7 servos required to use optional flaps) Pilot figure not included.
Recommended: Pitts style muffler
Product Manual - Parts Listing - Accessories Needed
Just ran your numbers through www.motocalc.com. Motocalc indicates your setup should run well.

As for the numbers, Motocalc predicts following for the $89 E-Flite Motor, both based on a 5S 4000 Mah LiPo and a total model weight of 6 3/4 pounds.
1200 Feet per Minute climb rate
43Amps, 770 Watts into the motor, 570 Watts out of the motor (74% efficiency)
9700 RPM on a 12-6 Prop

As a comparison, the $115 Hacker A40-10L motor predictions:
2200 Feet per Minute climb rate
52 Amps, 900 Watts into the motor, 820 Watts out of the motor (89.9% efficiency)
8900 RPM on a 13X8 Prop.

I've got a Hacker A40-10L, those numbers are pretty close. As for the E-Flite motor specifications. Don't know, never used one.

The Castle Creations Switching uBEC's are pretty good. I've got several of them, but for models of this size and larger, I use dual receiver power, first, the ESC uBEC, and the second, the Castle Creations 10 Amp uBEC. These must be isolated from each other with two $2.50 10 Amp Shottky diodes. (I've got drawings and part numbers if desired.)

DennyV
Retired and the days are just too short, busier than ever!
kyleservicetech is offline  
  Reply With Quote
Old 01-06-2014, 04:13 AM   #17
fhhuber
Super Contributor
 
fhhuber's Avatar
 
Join Date: Mar 2013
Posts: 1,550
Thanked 166 Times in 158 Posts
iTrader: (0)
Friends: (1)
Default

The kit's list expected weight does not include fuel.

I can't say for sure how my RV-40 will turn out regarding weight yet... I haven't started the build. I have 8 other airplane kits in the build que before I will get to it. I have no predictions as to what changes I will make yet.

I generally come out 10% below kit's listed weight for the ready to fly model when I am not making any modifications other than glue choice.

When I start making modifications, keeping the same power system type (glow/gas/electric) I tend to come out even lighter.

Then there's the changes I make when changing from glow to electric...
fhhuber is online now  
  Reply With Quote
Old 01-06-2014, 04:15 AM   #18
hayofstacks
Super Contributor
 
hayofstacks's Avatar
 
Join Date: Jan 2012
Location: Utah
Posts: 1,463
Thanked 109 Times in 108 Posts
iTrader: (0)
Friends: (4)
Default

or 730 watts on 4 cells for an even lighter setup...
http://www.headsuphobby.com/Firepowe...otor-C-105.htm

slow stock prop reversal. it flies! easily! 543 watt dual motor bipe slow stick. push-me-pull-you. 242 watt 3 channel slow stick. 365 watt mini ultra stick. 415 watt mini contender. 810 watt ultra stick .25e. 220 watt alpha 450 sport (retired).
hayofstacks is offline  
  Reply With Quote
Old 01-06-2014, 04:18 AM   #19
hayofstacks
Super Contributor
 
hayofstacks's Avatar
 
Join Date: Jan 2012
Location: Utah
Posts: 1,463
Thanked 109 Times in 108 Posts
iTrader: (0)
Friends: (4)
Default

http://www.headsuphobby.com/Power-Up...otor-F-586.htm

hmmm 1000w on 5 cells and a 12" prop.

slow stock prop reversal. it flies! easily! 543 watt dual motor bipe slow stick. push-me-pull-you. 242 watt 3 channel slow stick. 365 watt mini ultra stick. 415 watt mini contender. 810 watt ultra stick .25e. 220 watt alpha 450 sport (retired).
hayofstacks is offline  
  Reply With Quote
Old 01-06-2014, 04:40 AM   #20
tobydogs
love to build!
 
tobydogs's Avatar
 
Join Date: Jan 2010
Location: nj usa
Posts: 2,844
Thanked 197 Times in 194 Posts
Club: rcrcc rockland county,ny
Awards Showcase

Outstanding Contributor Award 
iTrader: (0)
Friends: (13)
Default

thanks for the responses. so the 6.25 lbs of the RV spec listed above.....what does that include? glow motor,tank . will it be the target weight I'm supposed to achieve with motor,esc,batteries. it's going to weigh more than 6.25, i never did find time to go down and start changing weight ratios around.

by this weekend the eflite power 46 should arrive and with any luck the three 2 cell zippy 4000mah40c batteries i ordered from the USA hk warehouse will also arrive by next week.

one thing I'm also hoping for is after experimenting with weight relocating ,the battery box i built Will still be usable. it will be even more open for air flow to travel over the 5 cell compared to the 7cell fit.

when i get the smaller motor i can also build a battery mount out of standoff spacers and bring it in closer to the fuse. again offsetting some weight closer to the cg. have a good night all,i have work again after a nice week off. stu

narrow is the place to land...wide is the space to crash....choose the narrow way!
tobydogs is offline  
  Reply With Quote
Old 01-06-2014, 07:14 AM   #21
fhhuber
Super Contributor
 
fhhuber's Avatar
 
Join Date: Mar 2013
Posts: 1,550
Thanked 166 Times in 158 Posts
iTrader: (0)
Friends: (1)
Default

The expected weight listed on the box includes equipment equal to the radio (RX, servos, battery,extensions), engine and fuel tank as suggested in the instruction, using the glues and covering as recommended in the instructions.

Often it includes an allowance for lead weights expected to be used to get the airplane's CG correct.

The list weight will be based on having actually weighed one or more models that are ready for flight, except empty fuel tank.

************

While "more power is almost enough"... you can add so much power that the airplane is just unpleasant to fly because its too heavy.

I use 6 cell LiPo in .60 to .75 glow conversions... and have used 6 cell in a .91 conversion. 4 cell is usually just fine for .40 conversions.
fhhuber is online now  
  Reply With Quote
Old 01-06-2014, 07:24 AM   #22
Larry3215
Look out for that tree!!!
 
Larry3215's Avatar
 
Join Date: Mar 2006
Location: Gig Harbor, Wa USA
Posts: 6,714
View Larry3215's Gallery63
Thanked 688 Times in 667 Posts
Club: Kitsap ARCS & E-FLAPS
Awards Showcase

90 Minute Thermal Duration  60 Minute Thermal Duration  30 Minute Thermal Duration  4kW 
iTrader: (6)
Friends: (21)
Default

Part of your problem is your batteries. I know you said you didnt want to change them out, but you have a lot more battery than you need for that model = excess weight.

Your batteries are capable of putting out well over 2000 watts if they perform to spec. If your model weighs 6 pounds, then that works out to 333 watts per pound. Thats way way waaaay more than you need to fly that model very briskly. With that kind of power you could easily hand launch the model straight up accelerating all the way and it would be out of site in seconds

Its also waaaaay more potential power than your motor or esc can handle, so its kind of wasted.

The only reason to carry that much excess battery would be to fly long duration, but with this type of model you really need to think light weight.

Electrics can be a pain when your trying to figure out all these details,

I think I need a signature.
Larry
Larry3215 is offline  
  Reply With Quote
Old 01-07-2014, 03:53 AM   #23
tobydogs
love to build!
 
tobydogs's Avatar
 
Join Date: Jan 2010
Location: nj usa
Posts: 2,844
Thanked 197 Times in 194 Posts
Club: rcrcc rockland county,ny
Awards Showcase

Outstanding Contributor Award 
iTrader: (0)
Friends: (13)
Default

your right Larry,

I've down sized the power system and battery size,this should put me at the 6.75 pound range using the power 46 and 5cell batt. with the power 60 and 7 cell i was just around 7.25pounds and it felt real heavy i realized it would fly like a brick with huge power.

i may also trim a few hundred more grams relocating the tail servos to the rear of the fuse.eliminate the pushrods inside the fuse and if need be I'll get a 80 amp opto esc and a cc ubec. i have confidence the rv will be very close to the 6.5pound range with plenty of power.

what you said about duration is why i use the 4000mah40c batts. i get 10+ min flights on the hog and gp extra with out depleting the packs and having plenty of juice left for go around if i have to wait to land.

so for the rv4 i will give up some aerobatic performance for duration.besides,the rv4 isn't a super high aerobatic bird but more for scale flight.

I'm glad i posted this question as it helped a lot to make a few changes straight off. thanks again gang,I've hit the thank button to every post here as everyones suggestions have been helpful. stu

narrow is the place to land...wide is the space to crash....choose the narrow way!
tobydogs is offline  
  Reply With Quote
Reply

  WattFlyer RC Electric Flight Forums - Discuss radio control eflight > Electric R/C Airplanes > Scratch and Kit Built Aircraft

« Previous Thread | Next Thread »

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
Soldering wires together FlyWheel Electronic Builders Workshop 73 09-28-2013 08:24 PM
Avistar Glow to Electric conversion Help Achmed Sport Planes (Formerly I/C & Gas Conversion) 30 04-16-2013 09:37 PM
Extreme Flight Extra 300 EXP__Clean Sheet Doc Austin 3D Flying 5 01-05-2013 03:19 AM


All times are GMT +1. The time now is 06:05 AM.


Powered by: vBulletin
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright 2005 WattfFlyer.com
RCU Eflight HQ

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



Page generated in 0.57273 seconds with 72 queries