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Posted by: greggold
21-02-2024, 12:17 PM
Forum: General
- Replies (2)

Thanks to several posts on the PRCAC whatsapp, I now have seen an amazing comparison of major radio brands. This video is a big deal, given no comparison  of this quality has ever been posted, AFAIK. It was posted in Aug 2023.

The video: https://www.youtube.com/watch?v=LargnWPSX04

It was made by a Canadian blog: https://www.thelightersideofrc.com/shop

The comparison included Futaba, Spectrum, Frsky (tested with single band 2.4 Ghz rx, and a dual band rx (2.4 Ghz, 900 mhz)), Jeti (4 rx types), Radiomaster (boxer and Tx16s running elrs), JR, and an obscure radio brand, Powerbox.

The test was a severe one with txs and rxs at ground level, given that it is well known RC links improve when planes are in the air. When the rx was driven 1 km from the tx at home base there was a dip in the road, and within a further 500m all the radios had glitches except the Radiomaster at 250 mw and 100mw power, and the Frsky with dual band rx. After driving past this depression in the road many radios did not recover a signal on the gentle incline up a hill (Spectrum, Futaba, JR, Powerbox). The ones that did recover were Frsky (single band), Jeti (all rx types), and RM at 25mw power (see attached results).

At around 5km the top of the gentle incline up a hill was reached, and on the other side of this hill all the radios soon lost signal: Frsky at 5.7 km from base, RM (250 mw) 6.6km, and the RM 100mw and 25mw at 5.7 km.

RM/elrs was the clear winner, even though it was placed at a disadvantage because RM's (arguably) best feature - dynamic power - was not used in the test. In second place was Frsky Tandem dual band; its interesting that the difference between Frsky single band and dual band was apparent.  At PRCAC, I found that Frsky dual band (2.4 and 900) gave no control glitches while single 2.4 band rxs had glitches. I sold my Frsky Tandem X20 2 months ago.

RM's win is more remarkable because it is priced lower than the other big name radios, and compared to Jeti, Futaba and Spectrum, much lower.

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Posted by: greggold
10-02-2024, 12:36 PM
Forum: General
- Replies (4)

Quite a few people use this rx. I thought I would try updating the firmware on one of my models which had elrs 3.0.1, even though it worked fine, given that the current firmware is now 3.3.2. I always update using the wifi method, and wifi showed my rx was running a firmware called generic ESP 8285. I first updated to the latest elrs configurator v1.6.1, and I saw that there was a Matek "R24-P PWM" rx firmware available, so I decided to give it a shot instead of generic.

I flashed this Matek "R24-P PWM" and Configurator said success, but the result was the rx no longer connected to the tx. So I repeated the flash with Generic ESP 8285 6xPWM, and this worked perfectly and rx functioned normally. Btw, I used firmware.bin.gz and I did not decompress this .gz file before flashing, as I once found decompressing the file can cause a "insufficient space" error. I think its a problem that matek allows this confusing situation to persist, whereby a reasonable person would select  Matek "R24-P PWM" rather than generic firmware, yet find Matek "R24-P PWM" does not work on its Matek R24-P6 rx. 

I will repeat this update on another model I fly with this rx, as the procedure is very simple, I do not remove or disconnect the rx from the model, just power up the model with the usual lipo and wait to get the wifi going. It occurred to me I should remove the propellor or restrain the model in case of an unexpected motor run, which has never happened so far.

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  VTOL

Posted by: greggold
20-01-2024, 12:56 PM
Forum: General
- No Replies

VTOL (vertical take-off and landing aircraft) have been around for decades and have uses in the military of several countries. The best known is the osprey, and unfortunately it has an appalling safety record, and continues to kill pilots ands crews to this day, despite enormous resources devoted to fixing the problem. Its clear VTOL flight is hard, especially the transitions between helicopter mode and airplane mode.

In the last year there have been a number of VTOL RC planes arrived on the market, that use flight controllers and gyros to assist the complexity and sheer difficulty of piloting these planes. A leading RC guru has recently posted experiences (and complaints) about them, along the lines when you flick the switch to transition, they crash. It takes many hours of painstaking work to set up the flight controllers so they work correctly, and this is left to the purchaser. 

Painless360 and VTOL

https://www.youtube.com/watch?v=0FOFyaubeR4&t=462s
https://www.youtube.com/shorts/k-xFs6PgpCY

Today I was surprised to see a VTOL plane at McCoy for the first time - and it did not have a flight controller or gyro! I think many will guess who the pilot was. It made a brilliant flight with safe transitions and a safe landing ... hats off to Andrew.

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Posted by: greggold
15-01-2024, 10:43 AM
Forum: General
- Replies (1)

Elrs already has solved my radio signal problems for line of sight flying at McCoy field, but the elrs project continues to improve the radio link in order to achieve better long range (ie 20 km) signal quality for fpv. 

I (and I think other club members) do not need to upgrade to gemini. Normal elrs does the job, given the current level of radio interference at McCoy.

But gemini is amazing. You can now purchase a full featured elrs gemini tx by Jumper, or a gemini tx module that fits any tx that can run edgetx/elrs. Gemini rxs are available, indeed last saturday I noticed someone in the club is already using one.

To get a picture of gemini this website may be a good place to start,

https://www.youtube.com/watch?v=7NUzkUWB0Ls

You can buy the jumper gemini tx for AUD $271 from Aliexpress.

For more detail on gemini check the Bardwell review:  https://www.youtube.com/watch?v=PZVUGKmBD24&t=928s

Bardwell uses the betafpv gemini tx module (cost AUD 130 from Fpvfaster) in his tests. https://www.fpvfaster.com.au/collections...tter-black

What is very interesting is the finding in the flight tests that using the module in the switching mode (so the tx signal is sent polarised in 2 planes at right angles, one antenna at a time) caused a notable jump in link quality performance. Having gemini mode working both in the tx and rx is required for maximum benefit, but there was a difference with just tx in switching mode. 

I am very tempted to try this module, as there is fairly little time required to reconfigure everything on my tx and planes if you just use the tx module. 

here is another test of gemini
https://www.youtube.com/watch?v=FoSREiyDQDA

I predict in a year or two we will all be using elrs gemini.

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Posted by: greggold
03-01-2024, 12:51 PM
Forum: General
- No Replies

I do not fly with a gyro, however I noticed a post about how Volantex 40cm span models that have a gyro (and come with a basic tx) can also be flown with a RM tx that is 4in1 tx, or module. Bill Clark goes through how its set up for the Volantex 761 planes, its a little complex but probably a good idea for these models.  

The vid is called 
EdgeTX Setting up the gyro function in a foamy park flyer
Its shown for the volantex 761 6 rc airplane

https://www.youtube.com/watch?v=pjkv3Xsn6BI&t=92s

I took a screenshot of the details of settings that Bill showed on-screen, but the picture would not upload to this website (I have previously noted the website can be unable to accept uploads for a period).

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Posted by: greggold
29-12-2023, 12:19 PM
Forum: General
- No Replies

Recently I posted a question on RCG about dynamic power jumps that occurred in 2 flights. The resulting discussion cleared up a number of fuzzy understandings I carried about the RC signal. Now we have elrs, not only are there no control signal problems but the RC signal can be understood in much greater clarity.

You can read the long version on RCG #2431 and following:
https://www.rcgroups.com/forums/showthre...em/page163


Here is a summary of the discussion. The question was about dynamic power: why do we occasionally see a TPWR jump while the RQly remains normal? (see plots attached, where Edge plot 2 is a zoom view of plot 1).

I was perplexed because I did not have a clear understanding of my radio signal. In the discussion it became clear there are 2 sorts of packets in the radio signal, control packets going from the tx to rx, and simultaneously telemetry packets going from the rx to the tx (I kinda knew it but not the key details... a bit fuzzy).
A telemetry packet is 10 ms and a control packet is the same duration. The following calculations are for a typical airplane elrs setup of frequency 100Hz, telemetry ratio 1:32.
We can convert frequency units from hertz to millisecond (period), given that 100 Hz is 1000 ms or 1 second. If all the signal comprised telemetry packets, then telemetry would arrive at the tx at a rate of 1000/10 or 100 packets per second. But telemetry is only 1/32 of the signal. While the control packets are arriving at the rx at almost 100/sec,  the telemetry packets are arriving at the tx at a rate 100/32 or 3.12 per sec.

Jumps may be triggered by drops in RQly, OR by falls in TQly (also by falls in RSSI and RSNR). See
https://www.expresslrs.org/software/...ransmit-power/
for a full discussion.
TQly is the percentage of missed or faulty telemetry packets arriving at the tx.

When Landru did a plot of TQLY and TPWR on data from the plotted Edge flight
the cause of the jumps was revealed (plot attached). The TPWR jumps correspond exactly to drops in TQly. The drop in TQly percentage is 4% (to 96%) for the 50mw TPWR jumps, and 8% for the 1000mw jump (attached) - in the Edge 16 plots the TPWR is divided by 2. This explains how dynamic power jumps occur with normal RQly.

Until now I had no idea I should be checking on TQly in my write logs.

When reading about packet rate, or watching online gurus, it is essential that we always be clear which packets are being discussed, rates are different for the control packets going from the tx to rx, and the simultaneously transmitted telemetry packets going from the rx to the tx.

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Posted by: greggold
27-11-2023, 05:14 PM
Forum: General
- Replies (3)

In this video Michael Wargo introduces the major 3D aerobatic manoeuvres.

https://www.youtube.com/watch?v=8f-NFMy_UqE

The details of the manoeuvres are only briefly explained by Wargo, but the list and selections are good. A quick google search on each of these names provides several videos that illustrate/demonstrate each manoeuvre in more detail. For example, for knife edge spin, I like 2 of many google search suggestions :

https://www.modelairplanenews.com/5-easy...ge-spin-2/

https://www.youtube.com/watch?v=ifbNaHtZ5bw


Harrier
Knife Edge
Rolling Harrier
Hover
Hover with Torque roll
Snap Flip
Inverted flip
Pop top crankshaft
Waterfall
Knife edge spin
Flat spin
4 point roll
Blender

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Posted by: greggold
04-11-2023, 01:25 PM
Forum: General
- No Replies

Aloft Hobbies (the US distributor of Frsky) drew my attention to a new (to many) RC brand, Causemann GmbH & Co KG (actually its been around for years).

https://forum.alofthobbies.com/index.php...dium=email

Aloft are excited about the almost-circular flying saucer Alix model (photo attached).
Alix maiden:
https://www.youtube.com/watch?v=tCgKWp_VyUc

However I am looking at the Ozalis and the Sambah, which are 83 cm span 3D planes (3D planes are called shockflyer in Germany)
https://shop-rc.causemann.de/Der-unzerst...Sambah-EPP
Ozalis costs euro 25.50, and Sambah 27.90

Sambah: "Made from 5mm EPP RG20, this means you can achieve almost the same take-off weight as with a shock flyer made from 3mm Depron.""

This video of Ozalis has it fly with a 3S 450 mah 50C lipo, and weight of 203 gm

https://www.youtube.com/watch?v=BnlC839FzrY

The control link gear is sold separately
https://shop-rc.causemann.de/Anlenkung-S...etc-GFK-V2

This site shows some details of the pull-pull linkage arrangement, including how to adjust the thread tension.
https://shop-rc.causemann.de/5mtr-hochre...ngshot-HLG

Most 3D planes eg Twisted Hobbies use long pushrods for ele and rud that are supported by tiny plastic guides. For commanding up elevator, its better that you arrange the servo so it pulls on the pushrod to give up ele, because when you push with the rod there is some flexion even with all the guides. In theory a pull-pull arrangement with thread used in the Causemann planes avoids this issue to achieve more precise control. 

In my experience 80 cm 3D planes can be flown in local parks, although I already have a few, I may try an Ozalis or Sambah.

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Posted by: greggold
19-10-2023, 03:59 PM
Forum: General
- Replies (3)

In the time of lipo shortage, I tried a new brand from PhaserFpv:
GNB GAONENG 650mAh 2S HV 7.6V 120C XT30 LiPo Battery FPV Drone Racing Light Weight LiHV High Voltage

I have been using these lipos to power several 80 cm span 3D planes for some time, and I have assumed being 2S lipos that they should be charged to 4.2 v per cell, total 8.4 volts. I think they perform well.

I today noticed they have a nominal voltage of 7.6v! Until now I have never seen a lipo with a "nominal voltage of 7.6v".

I posted a question on RCG:
On the website it seems all the Gaoneng 2S batteries have a nominal voltage of 7.6v. There is no advice on what voltage they should be charged to. I would appreciate if anyone can explain this. Can they be charged like all other 2S lipos are charged?

Fortunately I received a good reply. The above battery is not called a lipo, its a LiHV, which can be charged to either 4.2v per cell or 4.3 v per cell. It looks the same as a normal 2S lipo, and it performs well.

Oscar Liang provides useful details on LiHV.

https://oscarliang.com/lihv-lipo-drone-battery-hvli/

I plan to check my chargers whether they accept LiHV batteries, or whether they can accept a charge to 4.3v per cell.

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Posted by: greggold
11-10-2023, 03:45 PM
Forum: For Sale
- No Replies

SOLD

I am selling all my Frsky gear so I can focus my attention on one RC protocol. All the gear I have is in perfect working order.

I prefer to sell everything in one bundle.

The Tandem X20 tx is on sale for $320. 

There are 5 Tandem R10 rxs, 2 of which are new and unused. The new R10s $35 each, the used R10s $25 each 

2 R9 Slim rxs each $30

FrSky S2F.Port 2.0 Protocol Converter  $15

FrSky STK Tool for S.Port products Upgrading and S6R/S8R receivers Configuration  $10

The total value is $550 if items are bought separately. The entire bundle can be purchased for $450.

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