Author Topic: Starting Inverted Engines (Read 2204 times)

Garf · « **on:** August 08, 2009, 07:52:09 PM »

Over the years, I have had several planes with inverted engines. A lot of the older engines have problems starting inverted. I currently have a Nobler with a modified OS 35S engine that is the easiest starting inverted engine I have ever had. I'd like to hear about your experiences starting inverted engines.

Jim Thomerson · « **Reply #1 on:** August 08, 2009, 07:59:32 PM »

Fox 35, Squirt some fuel on the side of the piston, choke it four times, flip and fly. TD 049 on crankcase pressure, squirt fuel on side of piston, flip and fly. K&B 4011, at start of day, turn upside down, fill venturi with fuel, turn over, flip and clear the Rislone off the plug. From then on, choke twice, flip and fly. Of course you connect the gloplug.

Garf · « **Reply #2 on:** August 08, 2009, 09:15:50 PM »

I used to run Johnson engines inverted. Simply choking did nothing. Choke more and it floods.

Leester · « **Reply #3 on:** August 08, 2009, 09:37:32 PM »

I have found that the "Electric Finger" really helps.

Clayton Berry · « **Reply #4 on:** August 08, 2009, 10:34:07 PM »

I hold 'em vertical so the venturi actually drains into the crankcase. Thumb on the venturi, and a few partial rotations toward compression. A revolution or two, then return to horizontal with a battery attached. A bump, and then you're ready to go. This is with my ST 46, an OS 46LA, and an OS 35S. Results may vary.

Not that I've never had someone rush in at the last minute, flip the beast over and go at that propeller like a combat pitman. Thanks, Dick Houser.

Chris Gilbert IRL-1638 · « **Reply #5 on:** August 09, 2009, 11:46:45 AM »

I had real problems starting inverted motors up to about 2 years ago. Flooded or dry, and no in between that I could find.
And worse, the only advice I got was along the lines of "the secret is in the prime". Very helpful.

The situation got so bad I have an unfinished inverted motor model in bubble wrap, waiting to be finished.

Then I finally got my hands on a 2.5 cc syringe.

Now what I do is as follows:

When I get to the flying field, I burp the model inverted.

Typically the first start takes ~ 1cc before the motor will fire up, then continue burping it for a few cc of fuel, in 0.5 cc burps - after the first start it should start every time, first flick, with a 0.5 cc prime.

When I've proved that it'll start first flick I give it a final half cc prime and just turn to motor over a few times (no glow clip attached).

Then turn the model over and fuel up.

When I'm on the flight line I turn the motor over briskly for 10 or so flicks, signal the judge, connect my glow start and start the motor.

one or two flicks, works every time.

Garf · « **Reply #6 on:** August 09, 2009, 02:48:52 PM »

This OS S35 must be unusual. Hook up the battery, put the plane down on its wheels, finger over the venturi, 1/2 turn of the prop, 3 or 4 flips and it's usually running. I wonder if the stock S35 will do this?

Phil Coopy · « **Reply #7 on:** August 09, 2009, 05:08:06 PM »

I have found that when you are priming inverted that if you cover the venturi partly much like you do when getting a garden hose to squirt without a nozzle, the air jet will carry the fuel up into the port, ......then give it plenty of flips before giving it battery and is should start. I discovered this on a particularly hard starting inverted McCoy 35 on my Thunderbird II. Of course the electric finger thing works but they are hard on old bushed engines that don't have a hard washer between the crankcase and drive hub.

Phil

Matt Colan · « **Reply #8 on:** August 10, 2009, 08:05:31 AM »

For the first flight of the day with my Ares, I burp it to make it easier to start. I have to start the plane inverted, since I can't get my finger in it to prime it, so I have a little syringe that I use to squirt fuel in the venturi. I know how much to put in by feel, and 75% of the time, I have a 1 flip start.

James C. Johnson · « **Reply #9 on:** August 10, 2009, 08:39:07 AM »

This is an art... an electric starter works great and I use one these days because I put my "pride" in my pocket. It sure looks cool when you walk out in competition and Bam !!... the engine starts with one flip.. lines are perfect and and take off is fantastic..

I use the starter for the first start of the day, after that I seem to be able to get the engine to behave upright or inverted.. "the bump" is something that takes practice finding.. engines seem to start harder when it is cooler.. try starting an OS .10 FSR by hand when it is 32 degrees outside... upright !! Most of us don't fly when it is that cold.. but I have found the first start of the day to be the hardest sometimes... most of the OS engines I have, never have this problem.. when all else fails.. go to a hotter plug. Get the engine turning and "flipping over" smoothly before hooking a battery to it.. that is the key to a good start...

Jim

Phil Bare · « **Reply #10 on:** August 10, 2009, 03:00:11 PM »

Quote from: Garf on August 08, 2009, 07:52:09 PM

Over the years, I have had several planes with inverted engines. A lot of the older engines have problems starting inverted. I currently have a Nobler with a modified OS 35S engine that is the easiest starting inverted engine I have ever had. I'd like to hear about your experiences starting inverted engines.

Point the pointy end of the glow plug up, best way to start an inverted engine. :-)

Jim Kraft · « **Reply #11 on:** August 10, 2009, 07:31:51 PM »

What works for me on most engines is to hold your finger over the ventura, and pull the prop to TDC, and release your finger. You can hear the air/fuel being sucked into the engine. Two or three of these, and then just flip it a few times, hook up the battery, and start. Works great on Fox 35's.

Garf · « **Reply #12 on:** August 12, 2009, 11:42:27 AM »

Procedures seem to vary as much as the engines involved. I wonder how much the aftermarket ABC P&C I have installed has to do with the ease of starting this thing? I wonder if the stock engine would do as well?

Dave Adamisin · « **Reply #13 on:** August 12, 2009, 12:15:30 PM »

Quote from: Garf on August 12, 2009, 11:42:27 AM

Procedures seem to vary as much as the engines involved. I wonder how much the aftermarket ABC P&C I have installed has to do with the ease of starting this thing? I wonder if the stock engine would do as well?

The abc can't hurt but "in the day" an OS in contest shape always started on the first or second flip while on it's feet. We used to prime them buy putting the squeez bulb on the fill line with fuel in it and gently squeezing the bulb while flipping the prop. You kept on flipping untill the engine sounded "loose and a little wet". (DOH!! how technical is that). You hooked up the klips and signaled. Never had to feel for a bump because that wasted the prime and goofed up the start. Hit the prop smartly and walk to the handle...... and tried to not waste the good start.,.... The big OH.... you also need a fresh battery....

Brett Buck · « **Reply #14 on:** August 13, 2009, 12:31:58 AM »

Quote from: Garf on August 12, 2009, 11:42:27 AM

Procedures seem to vary as much as the engines involved. I wonder how much the aftermarket ABC P&C I have installed has to do with the ease of starting this thing? I wonder if the stock engine would do as well?

I started my bone-stock Fox first flip, inverted, thousands of time. It fit pretty good. The difference with the ABC/AAC is that they are pretty much *all* perfect fits and tend to stay that way. Very definitely hit-or-miss with anything else. A properly-fitted slug piston engine, at the right temperature, has essentially the same fit as an AAC. Hotter or colder, different story.

The ABC/AAC cylinder/piston assys are *much* more prone to starting with the battery off than just about anything else. It used to be a almost unheard of occurence, now its relatively common, once you get the technique of choking it down.

My technique is essentially identical to Jim Kraft's as described above. It's very difficult to flood the engine when it's inverted, and unless you master the "flip and aerate" trick, the problem is getting enough fuel into the engine to get it to start more than flooding it. The reason some people get hydraulic locks and the like is that to overcome the fuel dribbling out on the ground when you take your finger off, you keep choking and choking until you have too much. Once you get the intake stack filled with fuel, one more choke sends it all up the stack, runs down the shaft, and then into the cylinder - hydraulic lock. Excess fuel in the venturi just runs out onto the ground. The problem I always have with upright engines is if you choke it enough to get fuel up into the cylinder, it has too much in the crankcase to keep running once it starts. In fact, upright, I *never* choke the engine, I always just prime it and then aerate.

Brett

Bill Little · « **Reply #15 on:** August 19, 2009, 09:51:06 AM »

I always burp the engine before hand if at all possible. Otherwise I try to get the fell that Denny Adamisin talks about!

Wet and loose is the best way I can describe it, also. Hot plug and hot battery plus good fuel seems to do it pretty good.

The dumbest thing I remember was at Brodak's one year. I had the Geo Juno with the PA 51 and I had never had a problem with starting it. I had to do a NVA removal for some reason, and i was sure I had not changed the needle setting, but it wouldn't run! Dale Barry quickly just cranked the needle out and it started......... made me feel REALLY dumb!

Big Bear

john e. holliday · « **Reply #16 on:** August 20, 2009, 10:11:17 AM »

Seems that is happening more often now to us older folks. Kids have a way don't they? Have fun, DOC Holliday

NOEL DRINDAK · « **Reply #17 on:** August 24, 2009, 06:38:31 PM »

I've never had any trouble starting my inverted engines (usually first flip). My key is using the Bru-Line air filter (green). I fill the tank shortly before starting and overfill until fuel runs through the needle and drips off the air filter. The fuel that is left saturating the air filter is my prime. I flip the engine a couple of times to suck the prime up and into the cylinder (it seems to vaporize as it comes off the filter). I put on the glow driver and flip to start (with the big PA's it's easier to back flip the engine). If for some reason I lose the prime (like having the plane sit for a long time after fueling), I choke it for a couple of flips to saturate the filter and proceed as before. With this technique I've never found it necessary to take a plane off it's wheels to start the engine.

Yours in Stunt,

Noel Drindak

Brett Buck · « **Reply #18 on:** August 24, 2009, 10:02:16 PM »

Quote from: NOEL DRINDAK on August 24, 2009, 06:38:31 PM

I put on the glow driver and flip to start (with the big PA's it's easier to back flip the engine).

Not to mention a heck of a lot safer.

Brett

Mike Haverly · « **Reply #19 on:** August 24, 2009, 11:01:28 PM »

I'm using three different engines these days and am more surprised if I *don't* get a one flip start, at least on a warm day. LA 46, PA.40 and Ro-jett .40 all start about the same; choke 3-4 flips, flip through 6-7 times, back flip once, connect igniter, turn the prop to compression and back flip.

Garf · « **Reply #20 on:** September 06, 2009, 02:29:40 PM »

Does anyone have experience with the Brodak 40 starting inverted? I'd like to use mine in my next NoblARF. It seems easy to flood side mounted.

Jim Oliver · « **Reply #21 on:** September 06, 2009, 03:03:51 PM »

I have used one example of the B40 mounted inverted in an Oriental. I use a 4 oz. metal uniflow tank, and have a couple of layers of pantyhose material as an air filter. I fuel until I get a bit of fuel dripping from the venturi, then choke 3 or 4 blades, add the ignitor, pull through till I get a bump and then back flip to start. Many 1 or 2 flip starts............

Pretty much the same drill for my inverted PA 61 RE with header muffler.

Cheers,
Jim

Author Topic: Starting Inverted Engines (Read 2204 times)

Dave Adamisin