Hi I had great pleasure of my Viper until lately when i can't make it takeoff anymore. If it's because of the extra weight i added in form of a centerburner, seperate bec, and a plastic triangle in the tunnel for the wires and heavier trailing link landing gear i don't know. I'll post some clips and photos so you can see what i'm talking about. I don't feel the thrust is as powerful as it use to be. Would an upgrade of esc and motor get the extra power and maybe som better batteries with higher C rating do the trick? I'm close to buying the Avanti S high performance instead. Thoughts?
Eflite Viper too heavy
- Thread starter jangodog
- Start date
AUW? I think i have an old test with my watt meter before the mod. Should tell the thrust/wattage.
BlockerAviation
Legendary member
I think the biggest question to be asked is how old/how many flights do your batterys have on them?
A little more info. My lipos are Turnigy 3300 60C and 3600 30C. But if i wanna upgrade to a bigger motor say 2150 kv should i then also upgrade the esc to a 80 or 100amp esc? And do i then need bigger amp lipos aswell? Don't know much about the rc stuff. And last sadly
the nose broke off two times so have to make some reinforcement for it to stay glued to the fuselage.
the nose broke off two times so have to make some reinforcement for it to stay glued to the fuselage.
A little videoclip of the wattmeter connected to the Viper.
CarolineTyler
Legendary member
I would guess that it's not the weight added but the restrictions in the airflow.
You could try cutting a couple of cheater holes in the underside ahead of the EDF to add a bit more air intake.
You could try cutting a couple of cheater holes in the underside ahead of the EDF to add a bit more air intake.
CarolineTyler
Legendary member
I don't own that aircraft myself so cannot provide drawings/pictures. Sorry.
quorneng
Master member
jangodog
Be aware that kV does not denote the power of a motor but only the rpm it will try to turn at for a particular voltage.
The power of a motor is limited by the maximum amps it can handle and that figure is set by its design which is normally given by the manufacturer.
How many amps the motor actually draws is determined by the voltage applied and the size and type of the load which is a fan in your case. A higher kV in an identical motor design and fan and on the same voltage will draw more amps and produce more power.
Was the motor already installed in the Viper? Do you know its specification?
It appears from the video you are drawing 60A at full power which is about as close to the 70A ESC limit of the ESC as you want to get. The power is peeking at 1350W.
These figures do suggest the battery and fan are still working close to their original figures which unfortunately reinforces the view that it is one or more of the changes you have made that have effected the planes performance.
Could you remove any/all of them to see if the performance is restored.
Does your Viper weigh more than 70 oz ready to go? With a 3300 mAh 6s the Viper should be closer to 66 oz.
Be aware that kV does not denote the power of a motor but only the rpm it will try to turn at for a particular voltage.
The power of a motor is limited by the maximum amps it can handle and that figure is set by its design which is normally given by the manufacturer.
How many amps the motor actually draws is determined by the voltage applied and the size and type of the load which is a fan in your case. A higher kV in an identical motor design and fan and on the same voltage will draw more amps and produce more power.
Was the motor already installed in the Viper? Do you know its specification?
It appears from the video you are drawing 60A at full power which is about as close to the 70A ESC limit of the ESC as you want to get. The power is peeking at 1350W.
These figures do suggest the battery and fan are still working close to their original figures which unfortunately reinforces the view that it is one or more of the changes you have made that have effected the planes performance.
Could you remove any/all of them to see if the performance is restored.
Does your Viper weigh more than 70 oz ready to go? With a 3300 mAh 6s the Viper should be closer to 66 oz.
Hi. The Eflite Viper comes stock with an 1850KV motor. OZ. guess you mean the weight? Haven't really weight the plane but will soon. The most heavy of my lipos the 3300mah 60C weighs 561 grams. I bought the smaller packs just because of the lower weight for lighter flight. As i mentioned before i added a Castle bec 10amp weigh 15g. A centerburner 40g. twin/bogey main wheels alu app. 55g. Some paint not mutch.
A plastic tunnel for the wires and last the nozzle intake very thin alu. 15g Yes i know it all adds up. i flew fine with the new nozzle and 2 single wheels. Here is a little clip of my lates fail takeoff
A plastic tunnel for the wires and last the nozzle intake very thin alu. 15g Yes i know it all adds up. i flew fine with the new nozzle and 2 single wheels. Here is a little clip of my lates fail takeoff
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leaded50
Legendary member
mAh difference or ESC want give any performance gain, as long it fits the motor who is there. You need an another motor (or another EDF) .
The viper is delivered with - 2860-KV1850 , 6S 70mm edf, that gives max. thrust approx 2200-2400g .
the 3048 motor is recommended with 65A ESC at 6S, even if lower than the orginally 70A in your plane, it dont give answers if you gain something, but that motor for EDF fits your edf.
If that 3048 motor would give you better performance, check sellers/producers specs. You can also compare thrust, watts, and max.amp between edf´s with this specifications (motors used) and then see whats the difference if can gain performance, and recommended ESC .
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I'm talking about this one: https://www.motionrc.eu/collections...er-system-w-3048-2150kv?variant=8121308250161
Haven't seen specs yet on it. But how is it that a bigger motor like the 3048-2150KV only requries 65A esc?
Haven't seen specs yet on it. But how is it that a bigger motor like the 3048-2150KV only requries 65A esc?
leaded50
Legendary member
its differences in kv... and sadly it isnt shure that motor is bigger, it depends if both are measured similar way (if is measure on outside or internal. Normally it should though. When check in the link you gave someone sais that it ESC get a little hot, and would change to a 70-80A. So the kit could been taking this in concideration, but producer of EDF make a unit, who can be used in many different planes, and recommendation given from the EDF..... is not on a specific plane, who also impact the power the EDF need give (and the more power it need press out, the hotter it get) Someone wrote in reviews they measured 1100g on this EDF there..... that must be wrong though, but.... IF correct, that gives less power thrust. I would say its not correct.
Check specifications on 70mm EDFs with both motor alternatives, then you see the differences, and if will give you any gain by change. Thats the only way.
telnar1236
Elite member
It doesn't look too much like you're restricting airflow from any of the photos, but I can't really tell. My guess would be the attitude at which your plane sits when on the ground during the takeoff roll. Trailing link gear is great for stability and durability, but you need to make sure the plane always has a nose-high attitude or it will get pushed into the ground and have trouble taking off, especially from grass fields like you seem to have. Most of the issues I've seen with changing out stock landing gear come from this. If I had to guess, that would be the culprit. In terms of weight, I'm guessing your changes are going to be a non-issue. I don't personally have the viper, but from what I've seen, it has excess power when stock, and I've heard of people flying it on 5000 mAh packs, so I doubt you have changed the weight enough to create an issue.
Another thing to try is recalibrating your ESC. I think for most e-flite planes you just plug in the Rx with the throttle on the Tx advanced to full, wait for it to beep, and then drop the throttle until the ESC gives the normal sequence to indicate it's ready. It's easy to accidentally recalibrate an ESC and not notice which can result in losses of performance. The last thing to check is the center-burner installation. Again, I don't know specifics, but most designs I've seen draw from the ESC wires, so it's possible there's some kind of short in there that is robbing you of power.
Another thing to try is recalibrating your ESC. I think for most e-flite planes you just plug in the Rx with the throttle on the Tx advanced to full, wait for it to beep, and then drop the throttle until the ESC gives the normal sequence to indicate it's ready. It's easy to accidentally recalibrate an ESC and not notice which can result in losses of performance. The last thing to check is the center-burner installation. Again, I don't know specifics, but most designs I've seen draw from the ESC wires, so it's possible there's some kind of short in there that is robbing you of power.
