Infinity Grip starter pushbutton question
 

After some research and some sitting in the plane, I figured out it's going to be awkward to work the throttle, engage the starter, and hold the stick all the way aft (taildragger) without a third appendage. I've revised my design to the Aeroelectric option that allows for a pushbutton starter and I want to use the green button to the left of the 4-way hat. This button is rated for 6 amps. My starter circuit is 7 amps, according to the Z11 drawing. Am I going to need to install a relay for this circuit that will be engaged for one to five seconds or can I get by with a 6 amp switch on a 7 amp circuit? Is there a source for a slightly uprated version of that microswitch?

Is any motion of the throttle necessary? On the Piper Warrior I learned on, the trick was to engage the starter and in a quick motion, open the throttle up, then pull it back as the engine caught. If my setup is right, will there be a reliable 'start' position for the throttle so I can hold the stick with my right hand and engage a panel-mounted starter button with my left?

thanks,
-John

You have options...
 

My buddy and I both have an RV-7 and we both have the Infinity grips. His is flying and mine is under construction. He found that he can work a panel-mounted starter button with the left hand while working the throttle with the right. That leaves his knees to hold the stick back while starting. You will need a hand free to work the throttle, especially on hot starts.

I opted for the starter button on the stick, as I'm not really comfortable holding the stick with my knees. It just wasn't comfortable for me, and we'll leave it at that.:rolleyes: We'll soon see how this button placement works out.

Regarding the amp load, my schematic is out in the shop and it's too freakin' cold for me to go out there right now. But I seem to remember doing the current calculations, and the switch and 20 AWG wire supplied with the grip were going to be adequate for engaging the starter solenoid. I'll need to double check that, though.

I'm using the green button on my Infinity grip for my starter. I don't have my wiring charts in front of me, but I recall it was a pretty light load from the switch to the starter solenoid to close the relay and engage the starter. I didn't add an any other relay in addition to the starter solenoid.

I'm sure you've already taken this into account, but just in case... Be sure to follow the Aeroelectric schematic with regard to the starter disable portion of the diagram. You don't want to bump the switch and accidentally engage the starter while in flight!

FWIW, I really like having the starter button on the grip. It almost feels like I'm forgetting something because I no longer need a third hand when starting the plane.

I have a starter button on the Infinity grip that directly powers the starter relay, and no problems in ~700 hrs.

There have been past threads on whether putting the starter button on the stick is a good idea or not. Its definitely not a good idea if the button is always "hot", due to the potential to accidentally bump it. Mine is wired so that it doesn't work unless one of the ignition switches is on, and is disconnected when there is oil pressure (ie the engine is running). Other have discussed putting a disconnect switch on the panel.

Doing it again I'd probably put the starter button on the panel, just to simplify things. If you install a primer system there is actually not much need to work the throttle during startup. Just open it slightly, prime, and hit the starter. The Cherokee technique you mention makes use of the accelerator pump in the carb, which squirts a substantial stream of fuel into the intake manifold if the throttle is moved rapidly (if you try this with the carb removed the fuel will shoot several feet up into the air). This can be a bit of a risky proposition because if the engine isn't immediately started, that fuel will drain back down to the airbox, creating a fire hazard. Jockeying the throttle also increases the risk of having the engine start with the throttle wide open. If that happens you may find that full back elevator is not enough to keep you from nosing over in an RV. My understanding is that the accelerator pump is actually meant to provide smooth engine acceleration, not as a substitute for a primer.

If you've got fuel injection its pretty much the same deal, except the injectors do the priming.

Hindsight being what it is, I would put a starter button on my Infinity grip and move the rudder trim switch to the panel if I was doing it again. In my case, Vertical Power prevents the starter switch from being "hot" when you don't want it to be.

From Allan: ...I have a starter button on the Infinity grip that directly powers the starter relay, and no problems in ~700 hrs.

There have been past threads on whether putting the starter button on the stick is a good idea or not. Its definitely not a good idea if the button is always "hot", due to the potential to accidentally bump it. Mine is wired so that it doesn't work unless one of the ignition switches is on, and is disconnected when there is oil pressure (ie the engine is running). Other have discussed putting a disconnect switch on the panel...

=============================
This is a good way to do it (using oil pressure). The only exception is if you use an engine pre-oiler. I did a flight test by shutting down the engine in flight to determine if the oil pressure drops quickly enough to use the starter. Yes it does (for me).

In my HR-II, I am adding a relay in series with the starter contacter that is enabled when the master switch is in the "batt" position, thus allowing cranking only in this position. Once running, the master switch is set ot "alt" and stays there for the remainder of the flight, thus preventing accidental activation of the contactor. I have the starter switch on the stick grip.

I won't have an oil pressure switch on the HR-II. In the relentless drive to simplicity, it has been elimated and replaced with the oil pressure sensor used on my engine monitor. Ditto the hobbs meter.

V

Can't answer about a switch source but, I did use a relay and it does take a bit of mind work to wire it up but nothing that you can't do. If you can build an airplane the relay is easy.

I used 2 infinity grips and installed an isolator switch so the button is only activated for the stick I chose. This averts the chance of a careless or curious passenger hitting the switch by mistake. I need to mind my own hands.

Jekyll
7A

Don't have a tail dragger, but do have an Infinity stick and having a starter button on the stick sounds cool.

I'd probably switch to a solid-state solenoid for the starter circuit. They require less current to toggle. The Kelly E-Drive starter has a built-in solid state solenoid.

Another way
 

I have the starter wired using the pinkie switch, on the Infinity, and an ON-ON-(ON) toggle on the console/panel, using a remote relay.
When the toggle is off, all starter switches are non-functional. When the toggle is ON, in the center position, the starter is armed and the pinkie switch will work. Or, you can use the toggle momentary (ON) to start, in case the pinkie switch fails.
When the toggle is in the center "armed" position, a red idiot light is illuminated so you know it is armed. I only put the starter switch on the front Infinity grip. The same switch on the rear stick works the rear seat map light.
This is extremely easy to wire up using a $4 relay. I'll be glad to share the wiring diagram with you. (George Meketa originated this set up and it works great.)

Just a note on simplicity...
 

Let me say up front... I have nothing against having start on the stick.

That said, frankly, I don't find it a big issue not having it. I go to the panel to start now, and did on the SuperCub I rented earlier. Granted, I have a carb, so hot starts have not been an issue. I can't speak to FI applications.

Again, nothing against it if you want to do it. Just one more way to customize if you want to, but don't think your plane is going to bury the prop in the asphalt if you don't.