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Old Nov 10, 2007, 10:07 AM
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To offset or not to offset - That is the question!

I have a 3.4M Ventus 2C sailplane that is set-up for aerotow, but we no longer have a tow plane at our club.

I have been thinking of converting it over to electric self launch. Now, I presume 2 degrees down and 2 right is a good angle, but since we only use these motors for climb, does it really matter much?

Inquiring minds want to know.
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Old Nov 10, 2007, 10:14 AM
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Greeley, Colorado, USA
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No, it doesn't matter much. Generally, no need for any right thrust at all. A little downthrust is beneficial, but not necessary.

Just install the motor for the best fit of the spinner to the fuselage. If that can include some downthrust, great. If not, don't sweat it.

Good luck,
Lenny
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Old Nov 10, 2007, 01:03 PM
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Fairlie, New Zealand
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I don't put side thrust in mine at all, but if it has a reasonable amount of dihedral (which yours doesnt) then having no downthrust can make for an unusual climb - you have to hold in so much down elevator that it can tuck easily. For that reason, I put in as much downthrust as the fus will take.

Nick
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Old Nov 11, 2007, 06:56 AM
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I've found that at least 4 degrees is needed for the reasons stated by Nick.

Hugh
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Old Nov 11, 2007, 11:46 AM
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I agree. 4 degrees is not too much, usually I have to push down elevator during climb anyway.

Put a Cyclon Elite18 and a 5S LiPo in your Ventus, and go vertical Remember to buy a 18x11 Graupner CAM folder for it. Then be prepared for 500 meter in some few seconds if you dare to keep WOT...
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Old Nov 11, 2007, 06:02 PM
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Dartford, Kent, UK
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Yes, I think (without checking) I put in 4 degrees and then added extra shims to increase the downthrust further. I hand launch with slight up-elevator, releasing it almost immediately and then make slight adjustments to the elevator as needed.
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Old Nov 12, 2007, 08:17 AM
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We've been flying 2-meter (Gentle Lady, 2X6, etc.) sailplanes with Park 400 outrunners this past season and found that somewhere between 4 and 6 degrees of downthrust makes the climbout easier. If you get the downthrust right there's less need to re-trim between climb and glide. Holding down elevator isn't hard in the early part of the climb, but gets trickier the higher you get, so a hands-off climbout is a plus.
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Old Nov 12, 2007, 09:21 AM
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United States, IN, Indianapolis
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Ed,

Take this with some salt, but if it were me, I'd be hesitant to chop up the nose of that nice scale saiplane. Instead, I'd go for a power pod type option on that one (normally I'd say put the motor in the nose, but on that nice glass scale job, I'd be hesitant to, even if the tow plane in the club has disapeared).

There is a nice power pod sold by a few vendors, else you could make something.

Ryan
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Old Nov 12, 2007, 09:57 AM
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Thanks Ryan, but no power pods for me. If I go electric it will go in the nose.

If we ever get a tow plane back, I can put a release under the nose using a capture pin working through a slit in the fuselage.

I am not a purist when it comes to scale sailplanes. When it is up 500-1500 feet, the prop will not be noticeable. I can live with it.
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Old Nov 12, 2007, 10:07 AM
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rdwoebke's Avatar
United States, IN, Indianapolis
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I'm no purist either. Good luck with the mod. I'd suggest down thrust for sure. Probably on the order of what guys are suggesting here.

Ryan
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Old Nov 12, 2007, 10:35 AM
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Marietta, GA
Joined Jun 1999
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Aeronaut has some white blades that will help with the appearance, and if the nose is removed with a bandsaw, it would be easy to put it back on if needed in the future.

As to thrust offset, definitely some down, but you'll need to fly it to see how much is needed.
..a
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Old Nov 12, 2007, 10:42 AM
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Thanks guys. You have been most helpful.

I don't know if or when I will make this mod. I have plenty of other planes to fly, so there is no urgency to this. I just think it is a shame that this one will sit, unloved and unflown due to the lack of a tow plane and I don't have a slope suitable to fly it.

We will see.
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Old Nov 12, 2007, 11:04 AM
I'm all about that bass
rdwoebke's Avatar
United States, IN, Indianapolis
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Quote:
Originally Posted by aeajr
I just think it is a shame that this one will sit, unloved and unflown due to the lack of a tow plane and I don't have a slope suitable to fly it.
That plane can't be flown at Cape Cod? On the simulator, Cape Cod seems like you could fly just about anything there.... Seems to have a nice huge green landing zone too. Of course, a computer program might not reflect real life... :-)

Ryan
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Old Nov 13, 2007, 12:28 AM
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Maybe you dont need to cut the nose (well, no too much ) Take a look at pictures.
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Old Nov 13, 2007, 03:58 AM
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Quote:
Originally Posted by roblej
Maybe you dont need to cut the nose (well, no too much ) Take a look at pictures.
roblej,

Which Hyperion is that? 3025 - X is all I could make out (the light shine blurs the actual number). I can kinda make out a 12 . What prop size too
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