new to speed world

[HeliXXL]

So I recently won a 700 size regular 3D heli but I would like to build it more in line with a speed machine. obviously it is not a speed machine by design but I thought it would be a fun project and intro to the speed world. So I have a number of questions after reading some of the stickies. There is a thread regarding blades but I was wondering what other input people had on blade choice given all the new brands, designs, and options. Also what servos and power systems people are using and would recommend. I have always used a scorpion/castle combo in my other helis but I'm wondering what motor specs I should look for in a motor for 700 speed. Also would the fan on the castle 160 be of any benefit or is it pointless for this purpose and is a 160 big enough? As far as servos, there are so many choices in HV servos running in price from $99 to almost $200 each, brands like BK, MKS, RJX, SAVOX, etc. what should I be looking for in these servos and what have you guys had success with? I will be using a Vbar silver line for the FC so any suggestions for settings would be great too. I apologize if I am asking redundant questions, I've been out of the heli world for about two years except for an occasional flight so any and all help would be great!

[plankdriver]

All the servos mentioned are functional choices, since so many offer sub .12sec travel time, and over 150oz-in torque. To me is more important the servo with high control resolution, and does not need a flux capacitor to power then, that drives my preference to Futaba or MKS. Do your homework.

ESC: If you are going to 14S, then Castle will not do. Kontronik mostly dominates in that department, Hobbywing and YGE has good working alternatives. Otherwise the Castle 160 with a fan may serve your "initial" needs for thirst for wattage for quite a while. My motor of choice for the Castle160 and 12S setup will be HK-4530-540KV.

As for control the Vbar will work if your set up is spot on. If not...
The preference among very fast guys is been Bavarian Demon 3x and the good ol BeastX. 3Digi seems to work very well too.

Blades for speeds up to 140mph: DH711, Rail 716 F3c, Rotortech FAI tapered tip, and SAB speed will work well and nor break the bank. Above that, break the piggy for a set of X713s speed blades.

In the end what really matters is that components are balanced (motor-esc-batteries), your heli setup and program are tailored for speed and helps the machine fly easy, and that you practice a lot.

There are a lot of threads here that touch on that, but we always welcome specific questions; and although most of the speed guys fly for one or several companies, we do not subscribe to "my gear brand is the only one to have", but we rather point you to what will meet your
needs and gets you going fast, and faster.

Welcome to the brotherhood of speed!

What heli did you get, if I may ask?

Santiago
MHSFA

[LaDon]

Go with the 14s setup. There was an obvious difference power wise. Just my suggestion.

[HeliXXL]

Thanks for the tips! The kit I won is the KDS Agile 7.2.

[HeliXXL]

Is there a need for 470 oz of torque in a cyclic servo? Or would a regular servo with only 295 oz of torque speed around 0.049 at 8.4v frequency of 1520us/333hz work?

[K2Freak]

Is there a need for 470 oz of torque in a cyclic servo?

Nope.

would a regular servo with only 295 oz of torque speed around 0.049 at 8.4v (work)

Yes. Definitely. What servo is it that you are thinking of?

[HeliXXL]

I was comparing BK servos. Their standard hv servo has about 300 oz of torque while the 8000 series has like 470 oz. The RJX and savox seem to be in the same realm. I don't really have the dollars for $150 a servo right now.

[K2Freak]

Check out KST. Both up and comers, FWIW.

https://www.helifreak.com/showthread...=751437&page=5

[HeliXXL]

Awesome I will check them out.

[plankdriver]

For reference, I fly a 150oz-in servo in a 175mph class heli for 3 years. Zero issues.

Anything above 190oz-in is wasted torque. This is why I mentioned servo resolution is more important once you have enough torque, and then power economy.
Big torque servos require BIG POWER, keep that in mind because some BECs just cannot handle the power delivery.

FYI, the big Agile is a bulky heli aero speaking, but anything can be flown as a speed trainer.

-Santiago

[HeliXXL]

yeah i've been thinking of maybe trying to trade for a goblin speed or selling the kit and buying a speed machine.

[HeliXXL]

I have a castle 160 HV F on its way. Probably going to go with rail 716 speed main blades. What size tail blades are best or does it matter? Should I get 105 or 115?

[Justin Pucci]

Perfect setup! Be sure to run the castle with a cap pack on the front end to keep ripple low and go with rail 96's on the tail.

[HeliXXL]

Please excuse my ignorance but what is a cap pack and ripple that you are referring to? Also why the 96s on the tail? Just asking to educate myself. Thanks!

[K2Freak]

I'm no speed guy, but smaller tail blades is because you don't need the tail authority and level of compensation for speed that you do for 3D.

Cap pack is extra capacitors added right upstream of your ESC.

http://www.castlecreations.com/produ...-cap-pack.html

Roughly speaking, ripple current is variation in current that is not "clean" or doesn't happen right when it is supposed to. Here's a real description.

https://en.wikipedia.org/wiki/Ripple_(electrical)

[HeliXXL]

Awesome thanks for the info, I'll get one ordered. My ESC has already shipped. ordered it at about 10 am central and got a shipping verification at 11:30 am.

[Justin Pucci]

HeliXXL, take a look at my tech tip below:

https://www.helifreak.com/showthread.php?t=714548

The smaller tail blades are to minimize power losses to the tail rotor (more for the main rotor) since at these speeds, weathervaning plus light rate-mode control is sufficient to ensure adequate tail holding.

[K2Freak]

So, fwiw, small tail blades may be the only thing discussed so far that could limit you. I.e., go small enough, and you wont be able to tune it for other flight styles. Again, not a speed guy, but I suspect the marginal speed gain from dropping the tail blade size may not be as beneficial to you as the ability to tune your helicopter flight modes for all flying styles.

[HeliXXL]

I will probably get two sets of tail blades, one set of 95s and one set of 105 or 115. I should be able to set up banks on the vbar and simply select each bank with the gains and settings based on if I'm flying speed or gentle 3d. And switch tails if the 95s are holding well.

[HeliXXL]

Some speed aerodynamics related questions. So I read the thread posted by Justin Pucci and it was a very informative read. Also been reading in other threads and that has left me with some questions. They relate to blade pitch, blade stall and tip speed.

First how do i calculate tip speed? The way i calculated it is diameter×pi=circumference, cir×rpm (headspeed) = tip feet per minute ÷5280x60= tip speed in MPH. Is that correct? I have read that higher headspeed is better than greater pitch because more pitch at lower headspeed seems to equal RBS. Is this because of the separation of flow at the higher angles of attack at lower rotational speeds while flying at highspeed? Some have also stated that the limit of speed right now is blades and batteries/motors, what is the thought behind this? I apologize if this is the wrong place to ask I can move if need be.