Aruba

Hello all,
Do any of you have pictures of you throttle and choke hookups,
I'm trying to figure out how to do it.
The engine is going into a H9 1/3 Cap.
BTW this is my first gasser.

Thanks,


John

Giant Scale

Aruba,
Check out the users gallery on www.rcshowcase.com
they have a lot of pics of installations. Did you do a search on this forum, I seem to remember seeing some installs for this engine and plane combo.

rctom

I am using two microservos, one for throttle and one for choke, with a bisson mraparound muffler.

TF

VinceL

Speaking of the conections to the carb for the ZDZ 80, I have a question. I haven't owned a gas engine before with a choke plate that needed to be servo operated. The choke on the ZDZ 80 carb has a major detent that it snaps over on the way from open to closed. Does this need to be altered somehow to allow the servo to operate the plate smoothly? It would seem that there is enough resistance to put most standard servos in a stall situation. If it needs to be altered to operate smoothly what is the process to do so?

Antique

My Feedback: (4)

If you don't want the detent it can be removed..Take the screw out of the center of the choke plate.. pull the shaft out of the carb..The detent is a small spring with a small ball that fits into a depression in the shaft.Put the shaft back in without the spring and ball....

VinceL

R/C,

I have read numerous times that one really shouldn't fool with the screws in these plates. All of the ones I have seen on other engines are peened over to keep them from vibrating out. I don't remember if the Bing on the ZDZ is like this or not though. I have been told that if you remove the screw and reinstall it that it may come out later on and be ingested with catastophic results. How do you secure the screw after you reinstall it or is this something I really don't need to worry about? Is a drop of loctite going to do an adequate job?

Buzzard Dave

I too would like to know if these screws are in danger of falling out.

i did unscrew mine on my ZDZ40 to solder over the hole in the choke plate (then again to unsolder it). so far it hasn't budged - but is it likely to?


David Soniat - tampa, fl

Antique

My Feedback: (4)

Some are peened over, some have one way bumps on the screw, some have lock washers..If in doubt use a small lockwasher and Loctite..I use green 680 shaft and bearing mount Loctite..The screws are cad plated brass..The head will twist off before the Loctite lets go...The more common types of Loctite should work almost as well....

Giant Scale

Hey guys I had a couple of thoughts. I noticed that some of the throttle installs are using all metal pushrods and servo's right near the engine. I always thought this was a sure way to induce RF noise into the system. Everything I read says to use non-metallic pushrods. [Hey Roger..now is a good time to plug your fiber-optic servo extensions...just kidding :-)] I have both my choke and throttle servo mounted in the fuse behind the wing tube and used nyrod type pushrods. I did not notice a detent on the choke it seem to work fine with a standard servo. I'm using a hitec 5945 on throttle which seems to provide rock solid throttle control. My concern with using a standard servo on throttle was the holding power since I am not using a return spring on my throttle arm. VinceL the choke can be operated manually with a rod but the servo for me is more convenient.

Diablo-RCU

My Feedback: (1)

Holding power on the throttle?
Even if you left the spring attached, the load on the throttle servo on a gasser is next to nothing. I use a 42 oz-in servo with good centering and reliability. Even a mini servo has plenty of torque for the application.

rctom

In the installation photo from my earlier reply, if you look closely you may see that the engine is not connected electrically to the pushrods, there is a plastic connector in between. This is the most important thing, insulate the pushrod from the high voltage electrics.

Re: the detent and servo strength. I am using HS81 servos for both choke and throttle. These are 23 oz. micro servos. They aye plenty strong even for the choke with detent in place.

I like the detent, because it assures that the plate is fully open or fully closed. It also gives a nice solid "clink" when it moves, which sounds neat and attracts a lot of attention.

I adjust the choke servo by getting it close to correct mechanically, then I put it in either open or closed position and use atv to get rid of any buzzing. THis tells me that the choke is at full travel and the servo is also, so there is no binding or excess current draw. Do it at both ends of travel.

If the choke plate screw comes out while the engine is running you can kiss that engine off.

TF

Forgues Research

My Feedback: (7)

That's funny, yes with the Fiber Optic extensions you can do it with no worries

Forgues Research

My Feedback: (7)

Vince,
The detent you speak of should not pose any problems. But one should use a good servo on the choke and the throttle.
We tend to think that we can easily use elcheapo servos for these, but the throttle servo is used as much as any control on the airplane and you do need precision on the throttle.

Giant Scale

rctom,
I was not referring to your pic when I made my comments, I have seen this type of install in other planes. Look at the attached pic. All I'm saying is that from what I've read this type of install is a not recommended. Roger can probably give a better explanation than I can but I was always under the impression that radio components(servo's,batteries..etc) were to be kept away from the ignition system. Notice in the pic that the engine is soft mounted, RC Showcase does not recommend soft mounting ZDZ engines. But the gentleman who installed this engine did so, I guess for him that was the right way to do it. It's your plane and you can do what you want.
Diablo maybe holding power was not the correct term. The butterfly on my ZDZ turns rather easily, what I wanted to avoid was using a servo that could not hold the throttle position or wandered. Correct me if I am wrong but I thought that when doing 3D maneuvers, such as torque rolls, throttle management and precise throttle control were important. I just didn't feel that I could get this with a standard torque servo and the throttle on my ZDZ. This is just my opinion and I may be wrong.

Forgues Research

My Feedback: (7)

Your right in keeping the radio gear away from the engine/ignition setup. The only reason I get away with it is because I use the Fiber Optic extensions, sorry if this sounds like a plug again, but it does work.

I only use a digital servo on throttle and choke for its holding power. If you have a spring return on your throttle, then the digital is a very good idea because of the holding power .

bpryor

My Feedback: (45)

Everyone is correct that the throttle servo is not the place to cheap out. It is not the power that is important, it's the precision and speed. Diablo is correct that a top quality mini servo should be fine for the throttle, even with the spring, whether analog or digital. My favorite happens to be the Multiplex Micro digital(Roger ought to like that). Very fast (.07 transit), excellent precision and power and it weighs about an ounce. I've only used the older Mc2 versions of the servos, I'm not sure how the new ones compare.