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Richardmid1

rrProfessor

Leeds, England

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Anyone with live rpm readout on your tx, what does your rpm drop to in a full 12-13 pitch climb out?

60% of the time, it works every time!

08-09-2016 09:55 AM
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Four Stroker

Elite Veteran

Atlanta

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You can also do this with an MA Tach. For nitros the answer is the rpm droops magnificently. Say 2000 down to 1500. Some electrics may keep up as far as you can see it - a few seconds.

08-09-2016 02:48 PM
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Dawiev

Senior Heliman

Middle East

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Say 2000 down to 1500
Wow, that would not be fun to fly.

The key is a good governor, well-tuned engine, right amount of pitch and a smooth flying style. You cannot bang the sticks like an E.

No more that 100 / 150 drop.

08-09-2016 03:37 PM
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Richardmid1

rrProfessor

Leeds, England

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I guess it depends on the starting rpm. The lower within reason should hold rpm better.

60% of the time, it works every time!

08-09-2016 03:43 PM
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Four Stroker

Elite Veteran

Atlanta

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Well go to a field and ask the guys to blast off into the sky AT FULL PITCH and measure the rpm. You need a helper to actually watch the transmitter. 50% of the pilots will blast off at 3/4 throttle and swear it is full. At least with a nitro, it is an old wives tale that you can maintain 2000 rpm at 14 degrees pitch. Now at about 10 HP an electric can maintain the rpm much better until the ESC overheats and shuts down.

Now if you have 640 blades on a 105 you should do pretty well.

08-09-2016 04:06 PM
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Dawiev

Senior Heliman

Middle East

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If you want to fly a nitro like an electric, then.... get an electric!

14 degrees pitch? Even an E will struggle to hold that under the conditions you describe

I was very specific in the conditions required to maintain a good headspeed.

08-09-2016 04:27 PM
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Four Stroker

Elite Veteran

Atlanta

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I thought the OP got to determine the conditions in question:

"full 12-13 pitch climb out?"

Of course he did not specify what rpm to start with.

08-09-2016 06:58 PM
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Richardmid1

rrProfessor

Leeds, England

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I've only very briefly seen a friends nx7 at 1900 with rpm telemetry and was surprised how much the rpm dropped but you wouldn't think it by the engine sound. I can't remember how much it dropped exactly but it was a good 200-300 rpm. I think initially when giving full pitch the rpm drops a lot but after a couple of seconds it starts to climb again as the helis speed matches the air flow through the blades. I think an electric would do the same initially till the governor ramped the power in THEN it would hold more HS than the nitro in a continuous climb.

I'm still interested to hear some actual figures from people who have done such a test.

60% of the time, it works every time!

08-10-2016 06:05 AM
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ICUR1-2

Key Veteran

Ottawa, Ontario

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I dunno on a well tuned engine it will drop a couple hundred at most
Usually one tunes the engine doing a full climb out at full pitch to tune for power

spending time, paying attention

08-10-2016 06:15 AM
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Four Stroker

Elite Veteran

Atlanta

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Well with telemetry logging this is something that need not be speculated about. Measure it. Try whatever top end pitch suits your flying style. I know several guys who 3D and have 14 degrees top end pitch. If you blast off straight up 400 feet (AMA limit) at full pitch with a nitro and an electric, I think you will be very surprised.

All of my actual testing was on 90 nitros set up to do 3D at 12 degrees top end pitch. 2000 down to 1500. Now a 105 or 120 should be a little better.

A nitro does about 3~4 HP. An electric can do 10 HP for some seconds. So if set up properly it should not really sag for a climb out of 400 feet.

08-10-2016 01:03 PM
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Tyler

Elite Veteran

Chicagoland area

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A properly tuned nitro engine should drop down into the power and when fully loaded.

Also, full collective for 3d pop is suppose to only be used briefly to start and stop, not for long durations. Pilots with good collective and cyclic management get in and out of the pitch very quickly.

Enjoy things that money can buy IF you don't lose the things money can't buy.

08-10-2016 10:52 PM
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Four Stroker

Elite Veteran

Atlanta

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Yes of course. 3D is done with the kinetic energy stored in the head. But that was not the original question.

08-11-2016 02:12 PM
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ticedoff8

Key Veteran

Morgan Hill, CA. USA

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Two helis:
Trex 600E Pro with tri-blade tail and DFC head, 12S 3300mAh 60C battery. Programed headspeed is 1750 (low headspeed 3D).
Motor is a Scorpion HKIII-4035-530KV and CC Edge HV 120.

Trex 700N V2 with tri-blade head and tail.
Programmed headspeed is 1850 (normal headspeed).
Motor is a YS 120SR-X and Hatori pipe on 22% nitro

I use a TM1000 to downlink the data to my DX9 and log it to the SD card.

I don't see big changes when I hammer it.

My sig is not fit for public viewing.

08-19-2016 09:30 PM
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Richardmid1

rrProfessor

Leeds, England

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Is that time in seconds? Kind of irrelevant as we don't know what you were doing with the heli at the time. Also 1850 is low for a trex 700n v2 so it would hold better than if you ran 1950-2000.

60% of the time, it works every time!

08-19-2016 10:11 PM
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ticedoff8

Key Veteran

Morgan Hill, CA. USA

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Nice.
So, I should video it and match the time stamps to the log?

I'll get right on it.

In the mean time, DIY

My sig is not fit for public viewing.

08-19-2016 10:15 PM
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Richardmid1

rrProfessor

Leeds, England

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Or just record the full pitch climb out that I originally asked about?

60% of the time, it works every time!

08-19-2016 10:24 PM
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Four Stroker

Elite Veteran

Atlanta

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Well are we interested in 10 HP Electric OR 3 HP Nitro ? AND would 2000 be a typical hovering speed ? I thought we wanted to know how much sag there is from 2000 rpm with 12 degrees pitch in a full power full pitch NITRO climb out ?

But I am not the OP.

I am in fact an old guy who deliberately sets the top end pitch in idle up to maintain the same rpm from hovering to full power climb out. For a 600N this is about 9 degrees at 1800. This is optimistic and could be 1700 and 8 deg. depending on engine, fuel, blades and such.

I hear a lot of 12S bogging in tic tocs and ESC's are always shutting down. But of course this is because the guys I fly with are no damn good.

08-20-2016 03:03 PM
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