I have a Tower Hobbies tach and noticed I can get a better reading from in front of the prop, rather than behind it. I know from a safety standpoint you shoud keep yourself behind the prop. Is it becaues of the curve of the blade on the front as opposed to the flat blade surface on the back? Or am I totally off, maybe it's just the amount of light getting through the prop? What do you think?

Mostly it depends on where the sun is and where the clouds are. The tach is looking to count the number of times the prop breaks the light source. Sometimes I get a better reading from the front and sometimes from the back. It depends on the time of day and time of year which changes the angle of the sun. Just make sure the plane is held in place with a secure rope before you start.

What about on overcast days?

Just so you're pointing towards a bright area (As opposed to a group of trees).

The tach doesn't have to see Sunlight, but it needs to see daylight (Not indoor lighting)

Actually I usually find it easier to get a reading on overcast days than bright days.

And if you feel secure about standing in front of a prop with the engine running at full throttle, even with the plane tied up, search around for the post from teh guy who had his whole firewall come off. He TRIED not to catch the engine but didn't have much luck.


Andy

I don't think I want to read about that incident, I'm eating.

The color of the prop also matters, depending on the lighting situation. If you have a black prop, you can try painting some white stripes on the back of the blades. If it's a grey prop, try white or black paint.

I'm not sure the tachs pick up blocking the light, so much as changes in the lighting. If your back is to the sun, you might be counting "reflections" as opposed to shadows, for example.

I was thinking about using a tach to know if my engine is dead

Do they specifically make a sensor to know if you're dead stick?

I was hoping the tach could give me more info than if the engine is dead or not, but then again I don't know if it can't give me that kind of info.

Sorry to intrude on thread

Normally you are supposed to listen to your own plane and keep it in close enough so that if the engine quits, you will hear it slow down and then stop. There is a new computer that you can mount in the plane that uses sensors on board that will transmit all kinds of data such as engine rpm, altitude, speed, ect. to a box that is mounted on your transmitter but I just see it as another distraction from watching your plane and paying attention. [8D]

I always thought the best remote sensor to tell when the engine was dead was that the plane responded very sluggisly or not at all to throttle inputs....


Andy

Yep, Andy has it nailed. If you suspect you are deadstick, increase throttle and pull the nose slightly up. (I mean just a little, a few degrees). It should become pretty obvious if you're engine is running or not.

When in doubt, turn immediatly towards the field. If you're in doubt, you're probibly also far from the runway, and it might be a good time to do a low- to mid-level pass down the runway. And if it turns out the engine is dead, you're at least now gliding in the correct direction.