3DHS 87" Extra 300 SHP
- Thread starter gyro
- Start date
Park_Aviator
Member
I've just about got my 87 ready to go. The only thing I am having some trouble on is getting my throttle servo set up. I have it directly behind the fire wall. The problem that I am having is getting equal travel in both directions. I am consistently getting like 60% on the closed side, and 51% on the open side. I am programming with a spektrum dx8.
I have not set up many throttle servos because I have messed with electrics mostly. I did read that you want as close to equal travel in both directions for a good transition but I just cannot get there. I am using a hitec 645mg servo with the standard phenolic arm and a threaded 2-56 rod with ball links on both ends. I can post pictures if it will help.
Also, I am running two A123's with two seperate switches and running in to two different channels on the receiver. Do I need some kind of batshare or anything? I do want some kind of redundancy. Ignition is on a seperate 4.8v nimh.
I have not set up many throttle servos because I have messed with electrics mostly. I did read that you want as close to equal travel in both directions for a good transition but I just cannot get there. I am using a hitec 645mg servo with the standard phenolic arm and a threaded 2-56 rod with ball links on both ends. I can post pictures if it will help.
Also, I am running two A123's with two seperate switches and running in to two different channels on the receiver. Do I need some kind of batshare or anything? I do want some kind of redundancy. Ignition is on a seperate 4.8v nimh.
gyro
GSN Contributor
Wade.
IMHO, having "perfect" linkage matters less and less with today's radios. You can program the throttle curve to fix a small linkage issue.
As it is, a gas engine isn't linear in throttle anyway, so I always program a curve to suit my taste.
Just get it setup the best you can mechanically, then use your radio to set the 0-25-50-75-100 points to be wherever you get the throttle/rpm you want for that spot.
For your batteries, yes, a battery share is highly recommended. Multiple options exist based on price range, but one of the easiest is a Fromeco wolverine switch.
-G
I've heard a lot of good things about the wolverine and badger switches from fromeco. What is the advantage of running one of these versus just using two standard receiver switches hooked up to two batteries and then hooked up to the receiver? Does it have something to do with the batteries being used in parallel or something like that. Please forgive my ignorance.
joshgluck
100cc
The wolverine is what I use and really like it. Quality setup for dual high voltage 2s Lipos. Charging jacks too as I charge the packs in place. One benefit of the batt share and isolation is that if a pack fails the switch will ensure that it doesn't cause a failure of the other pack so you get a true redundancy that you do not get from plugging two Batts into the rx the way you suggest.. Perhaps others can explain electronically why that is. I have 5 of these switches now, some flying and some waiting for builds, and I am happy with them. The only comment I have for improvement is the mounting screws are aluminum and are easily stripped so go easy and use a nut driver on the other side!
gyro
GSN Contributor
Please don't ever ask for forgiveness on this site for not knowing everything... THAT is a huge reason this forum exists; sharing knowledge and helping each other.
The problem with two batts going into the same rx, is they "fight" each other, and they also can short out each other. If one bat fails, it can cause a short circuit and drag the other batts voltage down with it. With a battery share system like we're talking about, smart circuitry detects a failure like that, and isolates it. The better systems also ensure the batteries are drawn from in way that drains them nearly equally.
robj
70cc twin V2
Yes..
basically you want the servo arm pointing at the carb linkage as much as possible. This'll help with the expo. Then adjust the endpoints. I added some expo at the bottom of my throttle curve, about 30%. It's mostly linear but as I have found with my two gassers, most of the power still comes in the first 3/4 of the stick.
http://www.rcgroups.com/forums/showpost.php?p=22992911&postcount=10574
Last edited by a moderator:
3dbandit
100cc
Gary hit the nail on the head.
As for your battery situation you have a few options.
Fromeco wolverine switch, Smatfly Batt Share, MPI Miracle Switch, and Down and Locked RC from TBM also makes a batt share.
My preference is using a powersafe spektrum reciever. It has a built in redundant battery system.
Last edited by a moderator: