Hello-

I changed the prop on my Tower 46 engine from a Master Airscrew 11x5 to a wood 10x6 and the engine started to run in reverse. I've never experienced this issue before. The engine ran forward again after I changed back to the 11x5 prop. Any explanations for what may have happened here?

Bjfrankl

I have an engine that will always start backward. The solution I have come to on this particular engine is to start it backward- at that point, it always starts correctly.

One question- do you hand-flip to start, or use an electric starter?

I use an electric starter, but we tried hand starting the engine and it did the same thing. The engine has never done this for me before. I changed the prop and it started to run backwards.

Bjfrankl

The electric starter should have enough power to overcome the engine wanting to start backward. I used to own a tower .46 and I didn't have any trouble with that particular engine.

The engines starts backwards because it's overprimed, or a bit flooded. To avoid it happening adjust your priming procedure so that you aren't getting so much fuel in the cylinder.

Here's what I do:
- Without the glow starter on the engine open the throttle wide open.
- put your finger over the air intake in the carb, or over the exhaust outlet on the muffler if you have a cowled engine.
- Flip the engine counterclockwise until you see fuel pull up and start to enter into the carb.
- Flip it over a few more time to move the fuel into the cylinder.
- close the throttle to idle and put the glow driver on the glow plug
- start the engine.

If it still runs backwards reduce the number of turns you flip the engine after fuel enters into the carb. If the engine doesn't fire when you flip it increase the number of times you flip it

Hope this helps

Ken

I have to agree with RCKen here...the only way to overcome this, is by learning how many times to flip the prop when priming. Yeah when I'm lazy the day I don't count how many times and then the engine usually starts in reverse. However what I have also found works when you have already started up your engine and it is in reverse, is to "play" with your throttle...A lot of times you will get lucky and the engine will "throw" itself round and spin correctly.

If the engine is running backwards, first try rapidly pushing the throttle open. The engine will either sputter and then turn around, or it will sputter and die. If that doesn't work, and the fuel line is accessible, pinch the fuel line off while the engine is running backwards. Again, the engine will reach a point where it will turn around or it will burn off the over prime.

Brad

are you sure you did not fit a pusher prop?

I find any engine will sometimes run in reverse. I blip the throttle a few times and it corrects itself. No biggy

Your wooden prop was lighter thus having less flywheel effect. When the engine fired there was insufficient stored energy to carry it over the the next compression stroke and it kicked back reversing the rotation.

NB Lots of people make use of this quirk and by flicking the engine BACKWARDS get it to start running forwards.

I have a OS 46ax that will start backwards if it is over primed. I found that I only need to pull the fuel up till I see it hit the carb and its ready. If I turn the prop anymore it will start backwards.

You can also try lowering the the throttle trim to the point that it sputters and turns around. I've seen other techniques that I'm not so comfortable with.

I've got to say that I've never seen this problem when using an electric starter.

I seen this with a electric starterfrom when one of the jokers at the club swapped the positive starter lead on tothe negative of the battery for a laugh.

Now that's funny, I don't care who you are!

I have an OS .46 ducted fan engine that ran backwards. It had to be returned to Tower hobbies to be refurbished.
The engine never ran backward again after being repaired.


Henry

What he said,, You can use a heavy spinner to help you out if you are not use to running
a low rotational mass. This will slow down your spool up time but if you are not 3Ding it does not matter.

cheers Tim

I think the prop is the cause of my problem. I'm thinking that I purchased the wrong prop. The engine no longer ran in reverse when I installed the original prop back on the engine.

Bjfrankl

If that is what you think... read all these good posts again. If you still think it is the prop, have a nice day.

Please read post #9 and #15 and remember your physics class and you will see what is happening.
Always look for the cause and effect.
Cheers
Tim

Kmeyers

I said that the prop is the cause because that is what the MANUFACTURER figured to be the cause (I called the manufacturer after I created this post). They suspected that I put a pusher prop on the engine. Yes, I inadvertently purchased a pusher prop. I put my original prop back on (not a pusher prop), and the engine ran fine.

Bjfrankl

in that case post #8 would be the correct assessment... LOL

sometimes the simple things can create havoc

If this is the case the engine always ran fine.

It never did run backwards like your first post suggests. It ran in the correct directon but pushed air in the wrong directon while doing so.

You had it on the wrong end of the airplane for the prop you used.

You should apologize for wasting our time with this thread.

Do not get pissy with me for your mistake.

kmeyers-

I posted this thread because I didn't know what was wrong. That's why they call this the beginner's thread. I found your initial response quite inappropriate especially since I am relatively new to this hobby. I happened to speak to the manufacturer and we determined that the prop was the cause, so I posted that the prop caused the issue. Had I known this beforehand, I wouldn't have posted this thread in the first place.

Hey Meyers,

Easy on the newbies. Who died and made you the authority around here? You made a wrong call mate. If you don't understand a problem, ask more questions. Don't get snotty with folk.
I notoiced you had nothing positive to add to the thread in the first place, next time go visit www.shoooooosh.com for a zip it.

The individual asked a question and and looked to more than one resource at the same time. Thats not a crime.</p>

[Another one filed under AH]</p>

</p>

Keep it civil, Kmyers. As TimBle said, he's new at this, just like you were one time.


For bjfrankl, running backwards means that the engine is running clockwise (from the front) where it normaly would run counter-clockwise (again, looking at it from the front). My OS 75 and all three of my OS 1.20's will start up running backwards if I am not careful with how I start them. But, as TimBle said in a previous post, a little twitching of the throttle stick usually gets them running in the right direction, as they will sort of back-fire then get turning in the right direction after a few tries.

CGr.

WQW!!! glad I didn't post in this thread....[][][]