E7 Build

[colemn615]

Well, I got a-hold of a used E7 with RJX Servos. I currently run them on my E5s and really like them.

I have already started ordering parts. I took advantage of the memorial weekend and all of the 10% discounts on a lot of sites.

So far, I plan on swapping out the main gear to E7se, I also went ahead and purchased the 11t spur gear to speed up the tail if I want.

I plan on running 1900 on idle-up 1 and 2050 on idle-up 2. I want to make sure that I have a motor strong enough to handle those speeds at full pitch but not so much that I need to unload a ton of money on a motor. I fly sport only, well to the best of my skills haha.

As of right now.

• Cyclic - RJX FS0521 HV
• Tail - RJX FS0521THV
• FBL Controller - iKON
• Main Blades - 696 Rails (to be purchased)
• Tail Blades - 106 Rails (to be purchased)
• ESC - Castle Ice 120 (to be purchased)
• BEC - Castle Pro
• Motor - Not sure yet but with my flying style I don't need a ton of power I was considering 750mx 520kv with 12t pinion

I will be running two 6s 4500 40c packs.

I also went ahead purchased the Synergy key chain style canopy mounts. I ordered the Fusuno Rocket canopy as well since it's so easy to see on my E5s.

[halfcab]

May I suggest the 716 main blades, especially at your target head speeds and flying style, plus they auto better then the 696.

I do not agree with your choice of BEC, yes it's cheep and will work. Have you looked at Western Robotics.

[colemn615]

Originally Posted by halfcab

May I suggest the 716 main blades, especially at your target head speeds and flying style, plus they auto better then the 696.

I do not agree with your choice of BEC, yes it's cheep and will work. Have you looked at Western Robotics.

I have considered the 716s I don't really know the advantages of increasing the size.

As far as the BEC, I went ahead and ordered it but if I didn't trust it in the end I would just run off of a flight pack.I was unsure what size of flight pack to get. Why don't you trust the BEC I picked out? The WR ones are really expensive and I have heard of failures on those as well.

[flyalan]

Congrats.
Let me guess. You ordered a new canopy :-)

I would suggest the Castle Talon 120. Won't need a BEC. I would add the fan but I know from experience they can handle excursions above 120amps without issue. The Talon does not have logging but I do not see that as an issue

Cheers
Alan

[Digger1973]

3 yrs with my wr super bec pro. It has been on my electric and gassers. Bang for the buck I would recommend one.

[Thunder Fighter]

I always use a separate Lipo pack for my Rx on my bigger Heli's as I feel it's more reliable. With the telemetry on my Jeit I will never try and fly with a flat pack and I think that was the main reliability issue in the past.

Size of the pack will depend on how power hungry the servos are, I find a 2200mah pack on a 700 is a good size to start. If you have efficient servos (Futaba BLS for example) you will get plenty of flights from it, some of the HV coreless servos use more energy so you may end up with only 4 to 6 flights before needing to recharge it.

My e5 stretch has fairly efficient MKS BL servos and draws 125mah per flight so I have downsized to a 1300mah (45C) pack as I should be able to get 6 flights with 40% remaining in the pack. The high C pack is needed when you go to smaller packs to be able to supply the peak demands of the servos, with a 2200mah pack a 20C should be adequate.

For sports flying I would even suggest the 716 F3C blades as they track very well, giving good stability and give even better autos. They can still do 3d ok, but are great for Sports flying. I used them in an F3N (3d) comp recently and they were great.

//Dennis.

[Rodney Kirstine]

I've been using a CC BEC Pro on my E7 for over a year now and haven't had any issues with it. I have it wired to one of the 6S packs, though, instead of wiring it with 12S input voltage.

[Digger1973]

I don't wire my bec into the flight packs. Instead I use a seperate pack and just use the bec to regulate voltage as my savox are only rated for 6v. It does give me options to use whatever I want for a rx pack though.

[colemn615]

I have heard that the Rjx servos are pretty power hungry. Besides LIFEs on planks I have never used a receiver pack.

How well do they hold up to the 8.4 volts that I plan to use on those servos?

[Thunder Fighter]

LiPo's hold up very well. Testing yesterday I was measuring less than 0.3v drop when doing the Vbar brownout test, i.e. Fast Pitch pumps with the collective acceleration set to 100, with blades on.

I did the test with the pack sitting at 7.61v just above my 3.8v per cell telemetry warning (roughly 40% remaining charge) and saw drops to 7.35v with sustained pitch reversal. This is a worst case setup as I would have received voltage warnings on the flight before this and recharged and even Mikado says this test will show any weakness in your system supply.

This test was done with a small 1300mah 45C pack and shows that I will always have at least 7.4v available to my servos, Rx and FBL unit so will not see any real servo performance issues from flight to flight. I still remeber that Ray Dahl set Kyle's HV servo system back to LV on one of his Heli's and Kyle did not notice the difference even doing his Competiton training. So I don't think there is any way the majority of us would be able to pick up a 0.01sec change in speed between 8.4v and 7.4v.

Now the 0.3v drop is an average reading via my telemetry, there may be peak drops lower than this so it is always worth doing this test when setting up a Heli with either a BEC or an Rx pack to confirm the Rx will not suffer from a low voltage condition. You can find more info on Mikados Vstabi web site.

//Dennis.

[Rodney Kirstine]

Originally Posted by colemn615

I have heard that the Rjx servos are pretty power hungry. Besides LIFEs on planks I have never used a receiver pack.

How well do they hold up to the 8.4 volts that I plan to use on those servos?

FWIW, the E7 that I have the CC BEC Pro on has been running RJX servos the entire time.

[colemn615]

Yeah, I can understand where people are coming from with the CC BEC Pro. There has been failures but really all makes and models have failures. The most insurance is to use a flight pack but I was hoping to shave some weight. Maybe I shouldn't and should just get a flight pack.

Anyway, I was surprised no one complained about my motor choice.

As far as my flying style. I would like to eventually do 3d but that is probably a ways out.

[Grimmy]

I know it's added weight, but with a flight pack, you can move that around to help get your CG right. I use this for my flight pack:



Plus I can use that lipo in my Futaba 14SG as well if I needed too. I have a couple of these lipos just for this purpose.

[horigan]

I've had great performance with my BEC Pro on both my helis for years on 6S.

Be sure to get an SE pinion to go with the main gear. The slant angle is different.

[colemn615]

Originally Posted by horigan

I've had great performance with my BEC Pro on both my helis for years on 6S.

Be sure to get an SE pinion to go with the main gear. The slant angle is different.

I have already picked up the 12t pinion in anticipation of the 750mx motor.

[colemn615]

Well I got a bunch of goodies in today.

• Canopy
• Synergy Key Chain Canopy Mounts
• 121t Main Gear
• 12t E7se Pinion
• 11t Spur Gear
• RJX HV Tail Servo

I did notice that man it's hard to mount that canopy. I think I should replace the 21mm canopy mounts up front for the 17mm version. I had a few issues with that canopy in the beginning on my E5 but they went away once I had some wear and tear on the canopy.

[Grimmy]

Get some magnetic for the front and use the key chain style for the rears. I think the magnetic are from the Trex700 nitro:



Work great! Might take a little stretching at first but it will get better. If you would have told me I have a spare set of key chain mount there were an impulse buy, but I don't plan on using any more. Then again you're not answering any of my PMs so it wouldn't have mattered. Good luck with the build!

[colemn615]

Yeah, I reverted back to the front magnetic mount and gear key chain.

So I checked and I believe the spur gear shaft has a slight bend to it. I can see the nylon nut wobble just a bit.

Since I found out that the 11t spur gear requires the new frame I don't know if running on 106s will hold the tail.

My planned headspeeds are 1900 idle1 and 2050 idle2. I would prefer not to unload 160 bucks on new frame sides.

[halfcab]

New frames are not required, long-gate the three trans bolt holes per side.

[colemn615]

Just get a really tiny file and file away?

How do I tell if I have really good mesh?