tacho question

[adwb]

Hi, this is maybe not the right forum but I hope someone with experience will look here,or repost to another forum,
I have a model E006 digital mini tachometer made by hobby taiwan corp which is widely sold by hobby shops here in the UK.
It is for a hele great because you can clamp it to the boom and read the head speed from a distance while the hele is hovering.
My problem is that once my blade speed gets over 600 rpm the readings stop increasing and in fact will go back to zero as the head speed increases.
If I assume the unit is not faulty,
1 could this be caused by the fact that the blades I have in my raptor are wood with a white cover?
2 Is there any way to test a digital tacho to see if it is ok?
regards
Alistair

[Kwickkwack]

Just a thought, are you testing this indoors or outside, some flourescent lamps can give you a false reading when checking indoors.

[adwb]

Just a thought, are you testing this indoors or outside, some flourescent lamps can give you a false reading when checking indoors.

all testing out doors under a dull over cast sky which I though was the problem but the sun was out just now and the same happens.
Alistair

[timmmy]

i have one of them.if you have selected two blade and clamped it to the boom and the battery is ok then it shud just read it. if it says 125 thats 1250 if i remember right il have a look at it for ya but i can remember it doesnt say 1800 for instance.

[adwb]

Thanks Timmmy,
thats the right tacho, and yes the reading is x 10 so 180 = 1800 but what is happening is that above a certain speed it stops reading and reverts to 0 [zero] until you decrease the revs.
All very odd and I can't work out why.
what I have is pitch curve set at all points to give me zero pitch so she can't lift
All throttle curves at o% so at idle, then set the throttle lever on the tx to half throttle and start to increase the percentage of the point 3 throttle curve, as the revs and head speed increase so does the tacho reading but at about 90[900]rpm it gives up and returns to zero reading, if I decrease the throttle then the rev reading returns.
regards
Alistair

i have one of them.if you have selected two blade and clamped it to the boom and the battery is ok then it shud just read it. if it says 125 thats 1250 if i remember right il have a look at it for ya but i can remember it doesnt say 1800 for instance.

[Kwickkwack]

Daft question I guess, but you have got the reflective tape in the correct position on the blade so it passes directly over the light sensor

[adwb]

Durrh what reflective tape?? There was none with the tacho, was there suposed to be Or should I have bought some?? there is no mention of any in the instructions for the tacho
Alstair

Daft question I guess, but you have got the reflective tape in the correct position on the blade so it passes directly over the light sensor

[timmmy]

na you dont need any tape mate,if its set on the two blade prop function then the only thing i can think is it may be faulty or try a different place along the boom maybee? or is the battery running low or did you plug it into your rx.

[David Drew]

I have a digi tacho & when I tried strapping it to the boom I got nonsense on the readout. I don't think they like the vibes!

Try putting it on a screwdriver planted into the ground or buy an optical one.

[timmmy]

myns always worked ok strapped to the boom as far to nose end as it will go.but i think if it just drops off at 900 maybee is how or where its mounted,could try putting it on a brush handle or something so your not near it while its spooling up

[David Drew]

Honestly Timmmmmmmmmmmmmy, I tried real hard with my digi.

To get a good reading you have to be real close to the heli - scary - so I gave up. Bought an optical. Just so much better!!!

[adwb]

oh well, looks like I will be buying a optical tacho then, 1 last try tomorrow with some silver cooking foil on the underside of the blade if it will stick??
and I could try the screwdriver in the ground route but it is supposed to work on a boom.
looking at the picture on the destructions it is only about 50mm to the boom clamp.
if it's too far forward won't it "see" the paddles as well?
would that then be a 4 blade setting?
Oh so many questions and no answers
going to get a glass of red stuff and chill
thanks
Alistair

[helihead]

i agree get the optical tacho its accurate and you dont have to worie about the batterys or the extra tail wight you will be adding to the heli also you can use it on all your helis without hassle.

[David Drew]

oh well, looks like I will be buying a optical tacho then, 1 last try tomorrow with some silver cooking foil on the underside of the blade if it will stick??
and I could try the screwdriver in the ground route but it is supposed to work on a boom.
looking at the picture on the destructions it is only about 50mm to the boom clamp.
if it's too far forward won't it "see" the paddles as well?
would that then be a 4 blade setting?
Oh so many questions and no answers
going to get a glass of red stuff and chill
thanks
Alistair

That's why I gave up. Just go optical now and save a whole load of trouble

[adwb]

Whoopee it works, thanks Timmmy your comment re close to nose made me look at the tiny picture on the destructions and it is shown there close to the end.
You have to watch for the paddles or set it for 4 blades if they also pass over the tacho's eye.
I tried it again after at the balde tips and again it did not like it, figures drop off to zero once you get to 90.
thanks again
Regards
Alistair

myns always worked ok strapped to the boom as far to nose end as it will go.but i think if it just drops off at 900 maybee is how or where its mounted,could try putting it on a brush handle or something so your not near it while its spooling up