Help~Electric 2-Stage Pre-Rotater Wiring

NoWingsAttached

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Attached is a photo my customer's electric double-motor, two-stage pre-rotator. For safety, a heavy-duty solenoid relay is used to isolate power to the electric starter motors when not in use, but that is not the question. You don't need a solenoid to run the motor(s), for testing purposes you can run the battery lead to the motor housing and bypass the relay.

The question is: How do you activate the two motors separately for two-stage starting, first low and then high? There is only one low amp switch (activation) wire going to the housing, apparently it energizes a relay inside the housing.

Thanks, Greg
 

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bugflyer

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Centrifugal switch in the arrangement?
Timer switch inside?
Just thoughts.
smiles,
Charles
 

NoWingsAttached

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So this thing is a 24V system?

Does anyone know what this dual motor contraption is originally from?
 

Vance

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So this thing is a 24V system?

Does anyone know what this dual motor contraption is originally from?
The starter looks like a typical geared Denso starter off some Japanese automobile.

A single geared Denso starter on twelve volts will spin my thirty foot diameter eight and a half inch chord Sport Rotor to 120 rotor rpm in no wind conditions.

I feel, based on your questions you should learn more about electricity before proceeding.
 

NoWingsAttached

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The starter looks like a typical geared Denso starter off some Japanese automobile.
Ah, great, now I know what I'm dealing with.

I feel, based on your questions you should learn more about electricity before proceeding.
Bless your little heart, I apologize for never having worked on an electric prerotation system previously, however I am quite well-versed in electricity as well as electronics. Now that you mention it, I actually am quite intimate with electricity. In 1972 I was electrocuted in the rain by one of the 600 amp, 14.4Kv primaries off a "Y" feed while rebuilding a distribution line on the northern coast of Nova Scotia. It's a great story, really, but I won't go into it here. I also have a patent on a photoelectric alignment device, and spent a good part of my professional life as manager of a huge data center at 56 Marietta Street, Atlanta, while at the same time being the Georgia Regional Manager of a multi-billion dollar telecom - meaning I had to know quite a lot about troubleshooting all types of electronic devices and 48v DC UPS power systems, etc.

**********************************************

The owner knows very little to nothing about the system, as the gyro came to him with jury-rigged wiring. The soft-start switch never worked and the safety solenoid at the bottom of the mast was fried. It was by-passed by the original owner first with welding rod which lasted a handful of starts each, then a stainless steel bar which also burned up after a few uses, and finally a soft steel bar which is how it came to my shop in need of work. So far as we know it never had two batteries.

The wiring from the DPDT panel switch to the starter was melted along four feet of 16AWG wire, and had melted several other wires in the harness. He and I both think that one wire from the switch to the starter went through the relay coil, as the "Lo" energizer, using that solenoid coil as a resistor before going on up the mast to the starter where it activated the integral relay inside the starter+ reversing gear housing. A second wire from the DPDT switch - the "Hi" - then bypassed the solenoid coil (resistor) and ran directly up to the starter, while the "Lo" exiter was still engaged and keeping the relay on the solenoid closed. But that's just a guess I came up with this morning after reading the posts here to help us out, and talking with him on the phone.

The solenoid used was a golf-cart thing that was probably rated 80 Amps long-time use, and 300 amps brief use, like 5-6 seconds. Which woudl explain why the thing is burned out.

I found a 500A battery disconnect solenoid rated at 200A long time use, which I believe should hold up to the long burn required of a prerotator. Not sure if I will need to add resistors to the "Lo" side exitation or not, but no way am I putting coat hanger wire coils in the loom of a customer gyro, LOL!

I'm just trying to help him get it back in the air without spending too much $$$. I might bring it to Bensen Days if it's ready and the weather looks like it won't rain, since all 3 of our trailers are open.

I really have to buy an enclosed trailer soon.

Good Fast Cheap 2.jpg
 
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All_In

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The schematics are just my designs for a soft start prerotator system. Someone had asked 8 years ago how you design one and I drew these up and tested the 2nd 24-volt system. It increased rotor RPM by another 60% with 29' blades to 140 RRPM using a very small starter motor we had on hand.
 
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NoWingsAttached

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The schematics are just my designs for a soft start prerotator system. Someone had asked 8 years ago how you design one and I drew these up and tested the 2nd 24-volt system. It increased rotor RPM by another 60% with 29' blades to 140 RRPM using a very small starter motor we had on hand.
BTW, spoke with Dan from SDU this weekend, I think we have the wire harness questions sorted out. Travis was supposed to ship out the starter relay that was missing on his YG2 some time ago, but it got away from him (and me, as a result). Sorry for the delay.
 

Vance

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Attached is a photo my customer's electric double-motor, two-stage pre-rotator. For safety, a heavy-duty solenoid relay is used to isolate power to the electric starter motors when not in use, but that is not the question. You don't need a solenoid to run the motor(s), for testing purposes you can run the battery lead to the motor housing and bypass the relay.

The question is: How do you activate the two motors separately for two-stage starting, first low and then high? There is only one low amp switch (activation) wire going to the housing, apparently it energizes a relay inside the housing.

Thanks, Greg
There is a solenoid built into the starter that should be wired to the starter switch.

That is what the small spade connector goes to.

Many aircraft electrical systems have a solenoid hooked up to the master switch.
 

All_In

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BTW, spoke with Dan from SDU this weekend, I think we have the wire harness questions sorted out. Travis was supposed to ship out the starter relay that was missing on his YG2 some time ago, but it got away from him (and me, as a result). Sorry for the delay.
Dan from SDSU, we are working with SDU & now SCSU so it gets confusing.
Thanks for pointing them to Travis. About to call Dan and find out what else I need to order. I'll let you know if I cannot find the parts and you may know where?
 

Boots

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Several gyros at our hangar has the
starter pre-rotators .. none have soft-start -(no reason to have it)
I use a starter relay so there’s no hot power wires going up the mast in flight. I loop the start wire to the positive post on the starter .
Only 2 wires going to the starter
1 ground and 1 positive from the relay60DED70A-C578-47D7-86AE-7469D45CB98C.jpeg
 

All_In

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Sorry off the topic... Greg what fuel pump should we use. They have me searching for a 43 psi to the throttle body? Is that correct seems high to me?
 

NoWingsAttached

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Sorry off the topic... Greg what fuel pump should we use. They have me searching for a 43 psi to the throttle body? Is that correct seems high to me?
John:
There is a Summit Racing Fuel pump by Carter which is 45PSI, although the ad on SR no longer lists the pressure rating. I bought one for a customer install and tested it, it was spot on. The stock tank-mounted pump runs 43 psi. You can't mount it outside of the tank because it has its own regulator and return, no way to mount any fittings or hoses to it. Tango Gyro has been installing the stock pumps in their fuel tanks with success, though all of my customers use seat tanks and there's just no way to use the stock pump w/o a lot of time and expense to mount a stand-alone sump for the stock pump. There is a regulator on the fuel rail and a return line, so you can mount just about any pump 43+ psi you want. In fact I know folks using 65 & 75 psi pumps on similar Yami EFI systems. Check your fuel rail for a return hose, the YG2 I have in the shop right now has one, yours should too. If so then you are all set. I'll look up the Summit P/N and text it to you today.
 
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NoWingsAttached

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Sounds like I should forget about trying to include any soft start capability and just wire this up as a straight-forward Electric pre-rorotator, or as I like to call them, "E-pro".

Shown below is the 200A continuous/ 500A momentary, relay I found on Amazon for $26.99 w/ next day Prime delivery. It only costs $7.00 more than the 80A/300A golf cart jobbie posted above - which is what was on this gyro when it arrived - and should outlast it while allowing for much longer pre-ro times w/o overheating and burning out.

I wonder what melted the leads to the relay in the first place? They are just coil power after all, maybe a 10A max draw is possible, nothing the 16g wiring shouldn't have been able to handle and certainly not the primary power. Things that make ya go, "Hmmmm."
 

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NoWingsAttached

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Several gyros at our hangar has the
starter pre-rotators .. none have soft-start -(no reason to have it)
I use a starter relay so there’s no hot power wires going up the mast in flight. I loop the start wire to the positive post on the starter .
Only 2 wires going to the starter
1 ground and 1 positive from the relayView attachment 1146758
Thanks, Boots!
 

NoWingsAttached

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There is a solenoid built into the starter that should be wired to the starter switch.

That is what the small spade connector goes to.

Many aircraft electrical systems have a solenoid hooked up to the master switch.
I like the stock Yamaha fuses and relays, they are especially useful for pushers (gyros), where the panel is far away from the engine. On this one I am working on today, we have the stock FI relay mounted to the stock engine starter motor relay located high at the mag end of the engine next to the starter motor, and a separate relay to switch the keyed power for all the other stuff, mounted together and running through a 6-position fuse box on the R side of the mast.
 

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Thanks, Greg!
 

NoWingsAttached

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Thanks, Greg!
Here are the Summit part numbers for the 45 PSI fuel pump and adjustable regulator.

CRT-P74028 FUEL PUMP - ELECTRIC IN LINE
$62.99


TNK-AFPR1 FUEL REGULATOR ADJUSTABLE
$87.99

If you are careful you can cut away the stock fuel line from the fittings and reuse them with braided or plain (rubber) fuel line, and you will also need at least one more. Dorman P/N 800-080 comes 2 ea./pack for about $11.00, available at Amazon Fuel Line Barb Quick Connect 5/16" - Amazon

Yamaha fuel systems all require 5/16" ID fuel hose & fittings, these parts fit.

For SS braided line use AN6 fittings and 5/16" ID hose.

I was told that a failed in-line high pressure FI pump will not allow back flow. Because of this I have been using check valves only on carbbed engines fuel systems using dual pumps. Some folks swear you need them, but so far I haven't heard of a single case where back flow has occurred through a HP fuel pump using a backup pump. If anyone knows differently, please post your experience.
 
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