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RASA Prop Sizing for Neu Motor

Old 10-13-2009, 11:07 PM
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twoturnspin
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Default RASA Prop Sizing for Neu Motor

I have recently switched in a RASA 21x16 folding prop with a Hacker C50 14XL (1100kv) motor on an Integral and am very happy with the performance. It draws the came current as an APC 20x15 and delivers the same RPM (62 amps for 5800 RPM) but has signifcantly more thrust. My 2.0m new pattern plane (Tempest) is going to use a Neu 1515 3.5D which is a 1200kv motor with the same 6.7 reduction in the gearbox as the Hacker and I would like to use a RASA but am unsure which one. They have a folding 20x15 or a solid 20x15 which I thought might be good, anyone have thoughts on this please?

Incidentally, the only issue I am having with the RASA on the Integral is that the braking effect is reduced and I need to fiddle with the Spin 99 settings to get better downline braking with this. Has anyone got experience with this and able to pass on settings please?

Simon
Old 10-14-2009, 12:07 AM
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Default RE: RASA Prop Sizing for Neu Motor

Problem with the rasa (folding)prop is that you can not deduct the load from its size. The MAG 6, 21*16 is narrowbladed, the MAG 5, 20*16 is wider bladed and probably a heavier load than the 21*16. The MAG 1 21*15,5 is also a heavier load, a wider blade than the MAG 6 and the blade goes more to the hub than the MAG 5 and 6
Old 10-14-2009, 07:51 AM
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Default RE: RASA Prop Sizing for Neu Motor

Hi Simon

I don't know the exact loads with a Hacker, but here is my experience in order from lightest load to heaviest

21x14.5 - about 65A on a Pletty
21x15 - 70-75A
20.2x16 - 70-75A
20.2x17 - 80-85A
21x15.5 - about 90-95A on a Pletty

I have never used the 21x16

Sorry, I always forget the Mag #'s!

Can't comment on the Jeti either, but with the Schulze I use as much brake as possible and have a switch to activate it when needed. Maybe thats a solution for you?
Old 10-14-2009, 12:28 PM
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Default RE: RASA Prop Sizing for Neu Motor


ORIGINAL: twoturnspin

Incidentally, the only issue I am having with the RASA on the Integral is that the braking effect is reduced and I need to fiddle with the Spin 99 settings to get better downline braking with this. Has anyone got experience with this and able to pass on settings please?

Simon
When I was there, I think we set GlennO's brake to 30% and 50% (maybe final was 60%) and it was ok. I have my Comp set at 50% cause that's all it will let me do.
Old 10-14-2009, 01:20 PM
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Default RE: RASA Prop Sizing for Neu Motor

ORIGINAL: can773

Hi Simon

I don't know the exact loads with a Hacker, but here is my experience in order from lightest load to heaviest

MAG 2: 21x14.5 - about 65A on a Pletty
MAG 3: 21x15 - 70-75A
MAG 5: 20.2x16 - 70-75A
MAG 7: 20.2x17 - 80-85A
MAG 1: 21x15.5 - about 90-95A on a Pletty

I have never used the 21x16 (MAG6, for Hacker)

Sorry, I always forget the Mag #'s!

Can't comment on the Jeti either, but with the Schulze I use as much brake as possible and have a switch to activate it when needed. Maybe thats a solution for you?

Simon, hope you don't mind if I throw in a question in your thread concerning RASA props (I have added the MAG numbers as compensation):
if one is flying with the props still able to fold, can you use a brake? I am afraid that when the prop slows down, it will fold and hit the fuse.
I am flying with Jeti/Pletty combination but haven't used the brake setting yet for this reason.

Volkert
Old 10-14-2009, 01:26 PM
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Default RE: RASA Prop Sizing for Neu Motor

Volkert,

They wont fold with the brake, I run my blades quite loose and have never had them hit the fuse.
Old 10-14-2009, 03:56 PM
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Default RE: RASA Prop Sizing for Neu Motor


ORIGINAL: wagen017

ORIGINAL: can773

Hi Simon

I don't know the exact loads with a Hacker, but here is my experience in order from lightest load to heaviest

MAG 2: 21x14.5 - about 65A on a Pletty
MAG 3: 21x15 - 70-75A
MAG 5: 20.2x16 - 70-75A
MAG 7: 20.2x17 - 80-85A
MAG 1: 21x15.5 - about 90-95A on a Pletty

I have never used the 21x16 (MAG6, for Hacker)

Sorry, I always forget the Mag #'s!

Can't comment on the Jeti either, but with the Schulze I use as much brake as possible and have a switch to activate it when needed. Maybe thats a solution for you?

Simon, hope you don't mind if I throw in a question in your thread concerning RASA props (I have added the MAG numbers as compensation):
if one is flying with the props still able to fold, can you use a brake? I am afraid that when the prop slows down, it will fold and hit the fuse.
I am flying with Jeti/Pletty combination but haven't used the brake setting yet for this reason.

Volkert
I have been using the 21x16 folding for a while now and have been very happy with it. In Portugal i spoke to Manfred Greeves (i think this was the fellows name) about the prop and the possibility of it folding, he assured me it would not be a problem. He also advised me that not to tighten the blade holder (part that grips the blade) too much, leave them reasonably free. Probably helps tracking too.

Simon, i have yet to play with the breaking. It still is currently set on the same settings as i had on the 21x14 APC. It is faster in the down line with the RASA and probably could do with some more breaking

We'll see

Chris
Old 10-15-2009, 02:34 AM
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Default RE: RASA Prop Sizing for Neu Motor

Thanks for the thoughts guys, much appreciated. Interesting comments on tightening the blades Chad and Chris, I did mine up as tight as they would go as I was afraid they would hit the fuze! I'd better loosen them off a bit. I'll wind the brake setting up and see what that does for the downlines, I'm sure it will work out as Jason suggests.
Thanks especially to Hans, I did not know that detail about the loadings on the props and will keep it in mind.
As for the Neu motor, I'll have to experiment a bit. I'll start with a APC 20x13 and work out the loading and then work my way into a something like a RASA 21x14 or so. How does that sound to you guys?
Simon
Old 10-21-2009, 06:12 PM
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Default RE: RASA Prop Sizing for Neu Motor

Hi guys,
Just an update on my experience with the RASA MAG 6 (21x16):
1. I loosened the blades off like Chad and Chris suggested and it worked fine but I didn't notice any difference between the blades being tight and loose, probably less vibration if they aren't tracking I guess.
2. I wound the Spin 99 brake up to 60% after trying a couple of different settings and it worked much better in braking downlines. (You were right Jason)
3. I ran up a APC 21x14 and found that it drew about the same load as the MAG 6 but the MAG 6 was quieter, faster and had more torque.
4. Biggest difference in performance was using new batteries - incredible! Check out the measurements below, it will be interesting to see how the batteries decay over time.

(All flights on an Integral, Hacker 14, Spin 99. Measurements by e-Meter on the ground)

Using Hyperion 16C packs that have had ~ 80 flights each:
APC 20x15 - 35.9V, 61.1A, 2190W, 5730RPM
APC 21x14 - 36.4V, 61.2A, 2230W, 5730RPM
RASA MAG 6 21x16- 36.1, 61.1A, 2200W, 5730RPM
(RPM shows the same for all three but I guess the e-Meter rounds in some fashion)

Using Rhino 20C packs that were new:
APC 21x14 - 39.2V, 69.7A, 2735W, 5865RPM
RASA MAG 6 21x16- 38.9, 71.0A, 2758W, 5865RPM
RASA MAG 6 21x16- 39.1, 71.5A, 2798W, 6075RPM

I loved the power arising from the new packs but it messed my schedule around due to me not reacting fast enough to the increased pace. I guess I'll have to mortgage the house to buy more packs (and then start attending F3A Anonymous after my divorce)!

One of our Pattern Jedi, John Payne, popped the MAG 6 on his Hacker powered Tempest and reckoned he got 5-10% better performance from the RASA prop. I trust his judgement and that's a pretty good improvement if you ask me.

I'm convinced and happy to pay the extra money for these props. I plan to have my Tempest (with a Neu 1515 3.5D 1200kv) in the air next month and will continue to look for a suitable RASA prop for it. Still not sure what one to choose, I have been unsuccessful in finding anyone who is running a RASA on a Neu setup but very much appreciate the info detailed earlier in this thread.

All the best, Simon
Old 10-21-2009, 08:50 PM
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Default RE: RASA Prop Sizing for Neu Motor

Simon,

I might be stating the obvious but why don't you ask Steve Neu or Rasa directly?

Cheers
Jason.
Old 10-22-2009, 01:52 AM
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Default RE: RASA Prop Sizing for Neu Motor

Hey Jason,
I've written to Steve Neu but no reply as yet.
I can't find RASA directly so I wrote to Plettenberg who seem to be one the agents for RASA in Europe but they said the couldn't help with a Neu motor (not surprisingly).
Not the end of the world, I'll start with an APC 20x13 and keep researching a suitable RASA prop, doesn't sound like this combination is very common.
Simon
Old 10-22-2009, 06:22 AM
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matt13
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Default RE: RASA Prop Sizing for Neu Motor

Twoturnspin,
could you post a few pictures of your Tempest, the only photos I've seen of it so far have not had much detail. Matt
Old 10-22-2009, 08:06 AM
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Default RE: RASA Prop Sizing for Neu Motor

Simon,

Directly email Manfred Greve Jr., he is the designer of the RASA props and can probably provide you with more information regarding various setups for other motors.

I will PM you his email,
Old 11-08-2009, 02:12 AM
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Default RE: RASA Prop Sizing for Neu Motor


ORIGINAL: matt13

Twoturnspin,
could you post a few pictures of your Tempest, the only photos I've seen of it so far have not had much detail. Matt
Here's a few pics i have....more to come soon.

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Old 11-12-2009, 02:43 AM
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Default RE: RASA Prop Sizing for Neu Motor

HAHAHA! nice havvies!!!


Where are you guys getting the RASA's from in AUS?
Old 11-26-2009, 04:48 AM
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Default RE: RASA Prop Sizing for Neu Motor

"Manfred Greve Jr., he is the designer of the RASA props"

Is this a true statement? It might be the case for his folding props but the one piece versions are a definite APC copy.

IMHO the Rasa appears to be a direct copy of the APC E series props. The only difference being the APC logo is missing and they are carbon instead of fibre reinforced plastic. Rasa has even copied the metric and imperial prop size dimensions embossed into the prop.

Having said all that, the Rasa is only 2/3 rds of the weight of an APC....

Cheers
Jason.
Old 11-27-2009, 10:03 AM
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Default RE: RASA Prop Sizing for Neu Motor

I was strictly speaking regarding the folding blade props. Manfred does not make the props just design them. Since the singles are apc copies he doesn't have much in the way of design work to do
Old 11-27-2009, 03:07 PM
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Default RE: RASA Prop Sizing for Neu Motor

G'day Chad,

So I take it that APC have granted Rasa permission to copy their props?

I must say that they do seem to be very nice props and well balanced out of the box so to speak.

Cheers
Jason.
Old 11-28-2009, 10:45 AM
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Default RE: RASA Prop Sizing for Neu Motor


ORIGINAL: tonye5797

Here's a few pics i have....more to come soon.

Drooooooooooling
Old 12-23-2009, 02:55 AM
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Default RE: RASA Prop Sizing for Neu Motor


ORIGINAL: JAS


ORIGINAL: tonye5797

Here's a few pics i have....more to come soon.

Drooooooooooling
A few more......
Ready to maiden in the new year

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Old 12-23-2009, 02:58 AM
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Default RE: RASA Prop Sizing for Neu Motor

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