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Engine basics => Engine set up tips => Topic started by: Robin_Holden on March 17, 2012, 01:51:23 AM
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Greetings guys.
Can I ask about the prop' used with the Retro Discovery 60 engine with a muffler please ?
It appears to be a 13.5 x 5.9 . [ Yatsenko ]
Can anyone tell me what RPM this turns at launch please ?
Sounds like this mill is packed with low down torque !
Kind regards from the Charente ,
Robin.
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Hi Robin,
I have been told that the rpm is set around 8000. There is also another prop with just over 6 pitch. I haven't even run mine yet.........
Bill
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Hi.
If the engine parametres are ok, it's not necessary (and often not even possible) to use tacho. Just start from rich setting and turn needle in untill rpm starts oscillating just before solid 2-stroke. Normally the good launch rpm is the oscillating mode or just a little leaner, depending of tank position.
When you're happy with run, you can fine-tune flying speed by tweaking the prop.
Lauri
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Hi.
If the engine parametres are ok, it's not necessary (and often not even possible) to use tacho. Just start from rich setting and turn needle in untill rpm starts oscillating just before solid 2-stroke. Normally the good launch rpm is the oscillating mode or just a little leaner, depending of tank position.
When you're happy with run, you can fine-tune flying speed by tweaking the prop.
Lauri
HI Lauri,
How do you tweak the wooden Rainbow props?
Thanks!
Bill
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Hi Bill.
I'd rather use Yuriys props, they are better than Rainbow's.
You can tweak them using heat & pitch gauge, just like carbon props.
Well, allmost. The important thing is, that to get good results, you must get the section of blade heat completely hot. Not just the surface. So you must heat patiently and carefully to avoid burning the surface. Wood gets soft at about 100 degrees (Celsius).
The Yatsenko props I tweak only from the root. This is usually enough, and it also makes a nice wash-out towards tip (if I reduce the pitch). If there is need to tweak from closer to the tip, be carefull not to alter the airfoil. then just hold something flat (like a 1/4" sq. piece of balsa) against the blade bottom when you tweak.
To tweak, I pre-set the gauge to desired pitch and clamp the indicator so that it stays in place. Then I heat the root of prop, and then quickly put it to the correct groove in gauge and twist to correct pitch. It's good to tweak a little too much first, and then to return to correct angle. Only that way they stay like that.
People are usually very sceptical about this.
Yuriy's props differ from Zinger, Rev-Up and other similar crap because his props has pretty and well thought airfoils. So it's not very wise to alter their pitch by removing material.
L
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Hi Bill.
I'd rather use Yuriys props, they are better than Rainbow's.
You can tweak them using heat & pitch gauge, just like carbon props.
Well, allmost. The important thing is, that to get good results, you must get the section of blade heat completely hot. Not just the surface. So you must heat patiently and carefully to avoid burning the surface. Wood gets soft at about 100 degrees (Celsius).
The Yatsenko props I tweak only from the root. This is usually enough, and it also makes a nice wash-out towards tip (if I reduce the pitch). If there is need to tweak from closer to the tip, be carefull not to alter the airfoil. then just hold something flat (like a 1/4" sq. piece of balsa) against the blade bottom when you tweak.
To tweak, I pre-set the gauge to desired pitch and clamp the indicator so that it stays in place. Then I heat the root of prop, and then quickly put it to the correct groove in gauge and twist to correct pitch. It's good to tweak a little too much first, and then to return to correct angle. Only that way they stay like that.
People are usually very sceptical about this.
Yuriy's props differ from Zinger, Rev-Up and other similar crap because his props has pretty and well thought airfoils. So it's not very wise to alter their pitch by removing material.
L
Thanks, Lauri. I appreciate the information.
I have not had much success here in getting any props for the DR .60.
Bill
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Bill, the mezjlik 12.5x5.2 3 blade like I use on the DS 60 might work on the retro-ask Randy sometime. I ran it stock pitch on the DS, it has alot of undercamber and seemed to act like it had more pitch than the 5.2