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Sach 4.2 3D Prop at 6,500 ft???

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Sach 4.2 3D Prop at 6,500 ft???

Old 12-16-2012, 01:10 PM
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Default Sach 4.2 3D Prop at 6,500 ft???

Hello All,

On one of our 3D competition planes we are running a Ralph Cunningham Sach 4.2 (69cc). The guys on the team can't come to an agreement as to which prop to purchase for the plane, so we were wondering what you guys had in mind.

Again, reminder that the aim is to 3D with the aircraft and the Air Force Academy is roughly 6,500 feet in altitude. As of now we have a spare 20x12 to get it in the air, but I don't think that's the right prop for the Sach.

Thanks!

Cadet Tyler V Brennan
United States Air Force Academy
Old 12-17-2012, 05:35 AM
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Default RE: Sach 4.2 3D Prop at 6,500 ft???

What kind of airplane?
What scale?
What does the engine weigh?
Finally what is the all up weight of the airplane?

Bob
Old 12-17-2012, 06:41 AM
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Default RE: Sach 4.2 3D Prop at 6,500 ft???

he said it's a Sbach .. asumeing he wants to fly 3D


not sure what engine your runing that's 69cc but my guess you'd be aroud 25 x10 xoar or 26 x10 .. need engine type to look up it's prop chart

for a example DA 60 sweet prop is mez 24X10 your cc is some what close to the DA but your motor might have differnt porting and compression so that will change things a littel

Old 12-17-2012, 08:31 AM
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Default RE: Sach 4.2 3D Prop at 6,500 ft???

ORIGINAL: zacharyR

he said it's a Sbach .. asumeing he wants to fly 3D


not sure what engine your runing that's 69cc but my guess you'd be aroud 25 x10 xoar or 26 x10 .. need engine type to look up it's prop chart

for a example DA 60 sweet prop is mez 24X10 your cc is some what close to the DA but your motor might have differnt porting and compression so that will change things a littel

I take it you did not read and understand all of his post... He stated that he intends to fly 3D with whatever aircraft it is, however the Sack's power plant is by today's standard heavy and not as powerful, so I thought with a little of his airplane information we might be able to lead him in an educated direction.

Bob
Old 12-17-2012, 08:32 AM
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Default RE: Sach 4.2 3D Prop at 6,500 ft???

Flying a Lanier Extra 87, looking at coming in at around 19-20 pounds ish. And the engine is a Sach... not flying an Sbach lol Think the weight of the engine is approx. 5 pounds.

Really just wondering what you guys thought would be the best prop for the engine at altitude.

Thanks!
Old 12-17-2012, 08:56 AM
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Default RE: Sach 4.2 3D Prop at 6,500 ft???

The manufacture claims a 24x10 is a good prop for that engine. Those old Lanier 1/4 Extra's came out between 22 and 28 lbs. unless you placed the airplane on a radical diet and the Sack's 4.2 with exhaust, ignition, and battery are close to 6 lbs. So your at 6,500 ft and want to perform 3D. I hope you come out as light as you stated or you may be disappointed.

Bob
Old 12-17-2012, 09:08 AM
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Default RE: Sach 4.2 3D Prop at 6,500 ft???

I was thinking a 24x10 as well. And this article http://www.rcuniverse.com/magazine/a...article_id=611has it with a DA-50 at 17 1/4 lbs. They ran Nimh and I will have Lipos. Trying to offset the weight of the Sach as much as possible. The DAcomes in at 3 pounds, so I think a fly weight of 20 with the Sach is reasonable.
Old 12-17-2012, 10:42 AM
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Default RE: Sach 4.2 3D Prop at 6,500 ft???

I do wish you the very best in your effort.

Bob
Old 12-17-2012, 04:52 PM
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Default RE: Sach 4.2 3D Prop at 6,500 ft???

I dont think that plane will 3D very well by itself let alone with that engine installed.
Old 12-17-2012, 06:50 PM
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Default RE: Sach 4.2 3D Prop at 6,500 ft???

Guess we'll see what our guys can do with it
Old 12-18-2012, 08:04 AM
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Default RE: Sach 4.2 3D Prop at 6,500 ft???

Hope to see some video of how it goes! [8D]
Old 12-18-2012, 08:32 AM
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Default RE: Sach 4.2 3D Prop at 6,500 ft???

Starting with a Menz 24x10. Will see how it goes and letyou all know.

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