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Sep 28, 2019, 02:14 AM
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Quote:
Originally Posted by aeromodel03
Kiwidavid,

Your formulas are Ok for a first order type assessment provided that the pitch/diameter ratio is less than about 0.65. Beyond that they break down.

Thrust per Watt is a kind of ratio that obscures other factors. Look at the thrust formula. Decreasing rpm also decreases thrust. So does decreasing diameter or pitch. Hence there is a trade between Thrust/Watt and absolute thrust & power. - the greater the ratio the lower the thrust.


If your interest is in maximizing hover time you might find an article on that subject on my website under design and analysis notes.

https://rcaeronotes.wordpress.com/de...nalysis-notes/
Thank you so much for your comments and in particular the excellent links you have provided. I shall look forward to going through those in detail.
Yes it's a very basic set of formulas I'm using for a quad calculator which is returning good results over a range of craft. The Thrust/Watt formula I had hoped would show what I had always believed was the correct approach to follow - large diameter, slow revving props of low pitch.
I shall read your papers and hope to have a better understanding of maximizing performance rather than throwing more horsepower at it.
Thanks again.

Best regards,
David
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Oct 20, 2019, 09:14 PM
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Quote:
Originally Posted by vollrathd
Have you checked out www.motocalc.com? Free for 30 days, $39 gets you a lifetime license. Check out the Motocalc's "Opinions" tab after entering in all of the motor/model/propeller/battery data on your model.
Hey I checked it out, not a fan of the interface still but it’s leagues above drivecalc in that area and I like the wizard quite a lot, and i was able to transfer the information from ecalc to it, however something is seriously wrong with motorcalc.

As the throttle increases, the speed and rpm increase, but the power draw goes down and flight time goes up, 100% throttle gave the longest flight times in motorcalc no matter what I did.
Feb 02, 2020, 06:37 AM
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Quote:
Originally Posted by athiril
Hey I checked it out, not a fan of the interface still but it’s leagues above drivecalc in that area and I like the wizard quite a lot, and i was able to transfer the information from ecalc to it, however something is seriously wrong with motorcalc.

As the throttle increases, the speed and rpm increase, but the power draw goes down and flight time goes up, 100% throttle gave the longest flight times in motorcalc no matter what I did.
Probably something with Your input ... sorry ... It's the problem with such calculators, difficult to find correct input and the result become rubbish.

Some others experience with Motocalc
https://www.wattflyer.com/forums/showthread.php?t=61014

My experience for small motors and propulsion systems, bench test it's the only way at the moment. What could have worked
is if the motor/ESC/prop producers had taken e.g.Motocalc and feed it with their true data and made it available for the public,
then we might be able to get a bit better results.
Feb 22, 2020, 12:13 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
Thread OP
Three threads added to opening post, all three by topicstarter aeromodel03/Bill
  1. APCE Propeller Thrust Nomogram - RCG
  2. Excel programs for estimating model in-flight performance- RCG
  3. APCE Propeller Static Thrust & Power Nomograms - RCG
Prettig weekend Ron
Last edited by Ron van Sommeren; Apr 19, 2020 at 06:30 PM.
Apr 07, 2020, 01:30 PM
Registered User

DR1 87" 12lbs Lipo 6cells original reduction drive22/10


Can someone help me here? I am limited by my own inability to deal with computers and programs. I have an AXI 5340/24, Version 1. I know this motor will likely work because of the KV 197. What I need to know is the projected airspeed, electrical amps, RPM with the following props: 22/10, 24/10,28/10. I would prefer operating in the vicinity of under 40 amps and will use 6 l ipo cells. This airplane flew beautifully with a belt reduction/aveox drive at less then 1000 watts until the motor threw a magnet. I will, with your help pick the best combination. Thank you for any help or suggestions you may have. Stay Well out there!
Apr 07, 2020, 01:58 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
Thread OP
Better start a dedicated thread for your project Al, that way more people can view/help/answer you.
This thread is intended for compiling and discussing e-flight calculators and data, not for designing an actual power system.


Prettig weekend, en wees voorzichtig, Ron
• Without a watt-meter you are in the dark ... until something starts to glow •
• e-flight calculators • watt-meters • diy motor tips&tricks • Cumulus MFC •
Apr 07, 2020, 01:59 PM
Registered User
Fourdan's Avatar
Quote:
Originally Posted by Al Gross
Can someone help me here? I am limited by my own inability to deal with computers and programs. I have an AXI 5340/24, Version 1. I know this motor will likely work because of the KV 197. What I need to know is the projected airspeed, electrical amps, RPM with the following props: 22/10, 24/10,28/10. I would prefer operating in the vicinity of under 40 amps and will use 6 l ipo cells. This airplane flew beautifully with a belt reduction/aveox drive at less then 1000 watts until the motor threw a magnet. I will, with your help pick the best combination. Thank you for any help or suggestions you may have. Stay Well out there!
Hi
Maybe an Axi 5330-24 ?
Louis
Apr 19, 2020, 06:19 PM
Registered User
Louis,
My apology, it is an Axi 5330-24. to run on 6s/4000mah.
Al Gross
Apr 20, 2020, 07:30 AM
Registered User
Fourdan's Avatar
Hi
I have predicted the points for an AXi 5330-24 Kv 197
(with freeware Scorpion Calc starting with the S 5030-220 # 168)
Kv 197 rpm/V
Io 1.5 A
Rm 57 mohm
weight 650 g
6S
3 props with coeff 0.85 and 1.0
22x10
24x10
28x10
Attached screen shots
Louis
Apr 20, 2020, 06:06 PM
Registered User
Hi Louis, Exactly what I needed when working with 6 cells instead of 10 cells. You helped me hugely! I have the meters, just needed some confirmation.! Al Gross
May 22, 2020, 04:39 AM
Registered User
Hi,
Just tried to download Scorpion_Calc_v377.zip and I get a warning message "Failed - Virus detected". I think this is the first time I've seen Windows Defender give such a warning. I'm assuming it is safe but how do I get it to complete the download?

Best regards,
David
May 22, 2020, 05:51 AM
Registered User
Fourdan's Avatar
Hi David
Scorpion Calc is developped under VB6 since 2007
My PC is protected by Avast Premium
Many many downloadings without problems
v3.77 was downloaded 39 times : no remark
I suggest you to force the downloading
Best regards
Louis (author of SC)
May 22, 2020, 05:54 AM
Registered User
Quote:
Originally Posted by Fourdan
Hi David
Scorpion Calc is developped under VB6 since 2007
My PC is protected by Avast Premium
Many many downloadings without problems
v3.77 was downloaded 39 times : no remark
I suggest you to force the downloading
Best regards
Louis (author of SC)
Hello Louis,
Many thanks for your prompt and reassuring reply.
I will see if I can turn this embedded protection off for the download.

Best regards,
David
May 22, 2020, 07:04 AM
Registered User
Hello Louis,
Just for the record I have attached a screen shot of what Windows Defender thinks is the problem. You're not alone and others are reporting that continual changes in the Defender's virus profiles is causing these issues and making their software appear dodgy.
Microsoft has a submission process if you require it which should highlight problems with their profiles wrongly assuming it's a virus-
https://www.microsoft.com/en-us/wdsi/filesubmission

Best regards,
David
May 23, 2020, 03:42 PM
Registered User
Fourdan's Avatar
Hi David
I hope you have succeeded in the downloading
For information
The freeware Scorpion Calc v3.77 (zipped) is also available on the ScorpionSystem official website
Best
Louis


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