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Old Jul 27, 2002, 08:46 PM
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davidleitch's Avatar
Sydney Australia
Joined Feb 2002
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Will geared Phasor perform in hotliner?

I've been a bit unhappy(mainly my lack of flying skills) with the climb rate for a direct drive Phasor 30/3 on 10 x 6 and 10 cp 1700s in a 60oz hotliner.

I'm considering gearing it up @ 1.8 to one using the Velcom/Model Motor geaer box as sold by Espritmodel. I'd like to stay at 10 cells although I could go to 12 (just means a new battery pack).

When I run the figures through P calc it looks like this:


+-------------------+------------+----------+----------+
| | | | |
+-------------------+------------+----------+----------+
| Plane | | Spiro | Spiro |
| Unpowered weight | Oz | 30 | 30 |
| Cell type | | 1,700 | 1,700 |
| Number | | 10 | 10 |
| Motor | | Jeti 30 | Jeti 30 |
| Gear | | 1 | 1.8 |
| Prop | | 10x6 | 14x9 |
| Amps | | 30 | 48 |
| Thrust (static) | oz | 65 | 80 |
| Prop Pitch speed | MPH | 58 | 49 |
| Watts Out | | 272 | 250 |
| Power run time | M:s | 2:17 | 2:30 |
| Power weight | oz | 29 | 31 |
| AUW | oz | 62 | 64 |
| Watts/Lb | | 70 | 63 |
| Wing Span | inch | 69 | 69 |
| Surface area | Sq inch | 580 | 580 |
| Wing loading | ozs/sq ft | 15.4 | 15.9 |
+-------------------+------------+----------+----------+


Everything looks alright except the pitch speed. Is 49 MPH fast enough for this plane? Prop revs would be down under 6000. Does this matter?

Also any comments on the gearbox in question
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Last edited by davidleitch; Jul 27, 2002 at 08:53 PM.
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Old Jul 27, 2002, 08:57 PM
Tragic case
davidleitch's Avatar
Sydney Australia
Joined Feb 2002
5,875 Posts
Sorry
table didn't go so well first time.
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Old Jul 27, 2002, 11:02 PM
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Canada, ON, Ottawa
Joined Mar 2000
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Drop the prop size and add some cells. You will be much happier with more prop speed if I read that you have a Spiro correctly. Just watch you don't exceed the 20000 RPM limit of the Jeti motors.
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Old Jul 28, 2002, 08:46 AM
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Malaysia
Joined Jun 2001
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Hi David

Let me offer you a diff perspective.

My Elipsoid on 72~74oz 2.8M with 8 cell RC2400 , Mega 30/3(which is very similar to Jeti 30/3) 11x6 prop. And it will climb to speck height in less than 30 secs. Maybe about 750feet high.

I'm sure your setup will go faster than mine above given that you on 10 cell with 10x6.

My buddy have run Mytus 2.2M on 10 cell with Jeti 30/3 on 10x6. AUW about 70oz. Climb like crazy as well.
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Old Jul 28, 2002, 11:43 AM
"HE CRASHES"
GoodTill's Avatar
Hasbrouck Hts, New Jersey , United States
Joined Oct 2000
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My buddy has one in his Bandit
30/3 on 10 cp1300 and a 12/8 prop. He has unlimited vert at 90 degrees AUW 58 oz.

This would be the setup. You cant always go by the *calc programs. This is a little over the top, but you will only be on for a few seconds at a time.
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Old Jul 28, 2002, 01:16 PM
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Kyri's Avatar
England
Joined May 2000
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I have used my Jeti 30/3 in a Simba (2m glider) on 14 CP1700's and a RFM10x8 prop. Better to use the rfm prop because it is not likely to throw a blade.

With this setup, the initial launch needs a bit of lrvrl flight to build up the speed, and then the performance is vertical.

The Jeti on 14 cells is not comparable to a 10 cell F5B (which hass faster climbs) but its not far off. I have considered gearing my Jeti 2:1 and using between a 12x13 and a 15x15 with 14 cells. Thats just a guess, but it should perform well.

Regards

Kyri
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Old Jul 28, 2002, 10:08 PM
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davidleitch's Avatar
Sydney Australia
Joined Feb 2002
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Thanks all for the advice.

The existing setup flys the plane quite fast, but with not enough vertical. I ended up crashing on launch bad throw leads to roll (heading for trees so up elevator) leads to stall (95% no make that 99%) my fault (never stalled it on launch before). The other 1% more thrust would have helped.

The plane won't hold more than about a 30-40 deg climb without stalling although it has fast enough ground speed at the low climb rate.

Both the Bandit and Kyri's Simba have less wing area than the Spiro, and yet the Simba still needs a speed build up. I'm also a bit reluctant to run such a big prop and 14 cells on the Phasor because its over its rated spec. I'm sure its good for it, but I get nervous running stuff out of spec that I'm not really comfortable with.

Hmm maybe I should just bite the bullet and get a 50 Hacker. Cheapest option might be to learn to throw straight
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Old Jul 29, 2002, 12:20 PM
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St. Mary, Maryland, United States
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I'm running 11*6.5 Aeronaut blades on my Dymond Parabala with 10 cells and a Jeti 30/3. Climb is quite fast and strong, near 90 degrees initially and 60 degrees + towards the end of the charge. 10 second bursts are plenty for my particular hotliner style of flying.

Not sure what the Parabala weighs but it is fairly sturdy and goes real fast with the prop folded...

The RPM limit on the 30/3 is 15K NOT 20K so I would be reluctant to use 14 cells on a gearbox. A Mega 30/3 OTOH will take all you can throw at it, I run mine on 26 cells in an EDF.
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Old Jul 29, 2002, 01:30 PM
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England
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Chris,
Iwasn't sure what the rpm limits were for the 30/3, its good to know! I was unsure abou the 14 cells, so my rotor is Kevlar wrapped, and its so easy for anyone to do, with epoxy.
If buying new and wanting this much power, probably Mega is best. If wanting to push an already purchased Jeti, then wrapping the rotor is a good idea. Then, just make sure it doesn't stay too hot for too long (no good having magnets which are kevlar wrapped but demagnetised


Regards

Kyri
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Old Jul 29, 2002, 03:31 PM
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davidleitch's Avatar
Sydney Australia
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Quote:
Originally posted by Chris True
I'm running 11*6.5 Aeronaut blades on my Dymond Parabala with 10 cells and a Jeti 30/3. Climb is quite fast and strong, near 90 degrees initially and 60 degrees + towards the end of the charge. 10 second bursts are plenty for my particular hotliner style of flying.

Not sure what the Parabala weighs but it is fairly sturdy and goes real fast with the prop folded...

The RPM limit on the 30/3 is 15K NOT 20K so I would be reluctant to use 14 cells on a gearbox. A Mega 30/3 OTOH will take all you can throw at it, I run mine on 26 cells in an EDF.
Hi Chris

Any idea on the wing area of your Parabala? And I wouldn't mind a guess at the weight? I looked up the Parabala at the Dymond site and its listed but with no info.
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Old Jul 30, 2002, 07:58 AM
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St. Mary, Maryland, United States
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Quote:
Originally posted by davidleitch


Hi Chris

Any idea on the wing area of your Parabala? And I wouldn't mind a guess at the weight? I looked up the Parabala at the Dymond site and its listed but with no info.
I'll see if I can measure it tonight. I would guess the weigh is in the 60-70 ounce range. As far as I know the wing is 10 cell F5B leagle so it is pretty big.

The Parabala is a sturdy plane, hollow wing with lots a carbon in the spar, gap seals on the surfaces, metal inserts where the wing bolts go, and lots of kevlar in the fuse. I haven't owned any surprises etc. but I say the aerodynamics are similar, the airframe is probably a lot heavier. But then, it doesn't cost $800+!

Chris
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Old Jul 30, 2002, 06:29 PM
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OK, per my digital scale:

Fuse including motor and radio gear - 24.8 ounces
Wing - 21 ounces

Add to that the battery which for a 10 cell CP-1700 pack is about 16 ounces so it is 62 ounce RTF. Wing area is something around 540 squares, it is 2 meters and the average chord is 7.25 inches.
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Old Jul 30, 2002, 06:46 PM
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davidleitch's Avatar
Sydney Australia
Joined Feb 2002
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Thanks for info Chris

Hmm You are getting significantly better performance than me with slightly biggger prop but same size plane and power set up.

I'm not the world's greatest pilot but have had at least 15 flights and I definitely couldn't get anywhere near vertical without a stall on my setup.

Theoretically should be able to (thrust 60 oz plu compared to weight 60 oz and not much drag).

In any case I have decided to do 2 things:

1 Get the Velkom gearbox and try it (doesn't seem like anyone is actually using it in a sailplane with the Phasor). Should be no trouble even on 12-14 cells keeping the revs below 10K. I ordered the 2:1 ratio it is only $US40. I will post results eventually.

2 Get a Hacker. Life is short, I am sure the motor will last a lot longer than any plane I have. I have not seen many complaints about Hackers, or Kontronics.
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Old Jul 30, 2002, 07:03 PM
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davidleitch's Avatar
Sydney Australia
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Its also interesting to note that on the 10x6 and 10 cells the watts/lb is in 60-70 range. That would not normally be regarded as enough for really strong vertical aerobatics in a sports plane.

For instance I also run exactly the same power setup in a Multiplex Skycat. Completely different design (low wing EPP foam plane with undercarriage) 55 0z AUW, 450 sq inch wing area . Flys fantastic but definitely doesn't have unlimited vertical (will outside loop comfortably but not like a rocket, maybe good for one vertical roll).
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Old Jul 30, 2002, 08:31 PM
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Going up 1 inch in diameter and a 1/2 inch in pitch make 25% more power. Of course that assumes you battery construction and ESC can deliver nearly 50 amps. My ESC is a 70 amp Jeti and the cells are soldered end to end. I used to fly on 8 cells with the same prop, climb was not bad but not in keeping with the planes performance when going downhill. I went to 10 cells and now it is great.

I have started launching at 1/2 throttle. When tossing it by myself at full throttle it would pitch vertical and require full down elevator to get the nose down a bit at the start. Launching at 1/2 throttle, accelerating for a few feet then going to full makes it more managable.
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