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Member postings for PatMc

Here is a list of all the postings PatMc has made in our forums. Click on a thread name to jump to the thread.

Thread: Wiring a Twin
12/10/2018 22:50:53
Posted by G-JIMG on 12/10/2018 22:28:38:


Regarding connecting the batteries in parallel; it's not recommended because if the voltage is different (more that 0.03V per pack) the current transfer from the high voltage pack can be huge and end up damaging both batteries.

That's baloney, there's more chance of one battery failing before the other & causing an unexpected single motor spiral dive.

What does George's guarantee cover if your model is written off due to one ESC failing ?
A replacement ESC ?

Personaly I'd go with parallel batteries & 2x 45A - 60A opto ESCs installed in the fuselage with extended ESC to motor leads. There must be plenty of room in the fuselage to allow for adequate ventilation for batteries & ESCs.

Thread: Returning old timer.
06/10/2018 21:12:51

It could be viewed as a scale like feature in the same way as retracting tip floats etc might be, Percy.

Thread: Electric Junior 60 Watts Per Pound
06/10/2018 11:22:35

Keith, Doculam is heat activated self adhesive film.

06/10/2018 00:09:33

Hi Dave, thanks for the explanation.

I did some tests about 5 or 6 years ago with a scaled up by 10% vintage APS Frankenstein that came up with similar results to yours, albeit they ended abruptly after only 4 or 5 flights & I only kept record of one flight, though it was typical of the rest.
Frankie had previously flown with ic power, was later converted to brushed can 480 motor on 7 cell nicads finaly upgraded with a 2200KV BL inrunner with an inefficient 2.3:1 gear box using Etec 2500 3s lipos of around 7C rating.
The tests consisted of full power climb out for 60 seconds then stooging around at cruise power for about 15 minutes (with a few mild aerobatics thrown in to break the boredom) then landing, the model had an altimeter on board.

The record I did keep :
Weight : 35 oz , wing area 430 sq ins, wing loading 11.8 oz/sq ft.
Power : 9x4.5 prop; 8.85v, 10.2A, 90Watts, 7500rpm @ WOT.
Flight : Max altitude 374 ft in 60 secs, 16 minutes total flight time. Rate of climb 6.3 ft/sec. Battery recharge took 1064mAH.

So that's about 41W/Lb @ WOT & average of 5A current during the flight. It would be difficult to estimate the average watts taken as the voltage would have gone up considerably during the cruise phase.

The tests ended when the rattley GB fell to bits during the last flight teeth 2 the models been in storage since then. Frankie's overdue a refurb, new motor with decent lipos, probably will be recovered with tissue over doculam as per my Amigo glider, so should lose a few oz as well.

frankie.jpg

05/10/2018 20:36:55
Posted by David Mellor on 05/10/2018 17:48:20:

So..... how many Watts Per Pound does it need to fly???

The answer - based on 9 flights of 15 minutes duration each (using 3S 1500 mAh Zippy compact Lipos) - is 48 Watts in total.

Since the weight is exactly 2.5 pounds, the Watts-Per-Pound figure is just 20 Watts-Per-Pound, based on two hours and 15 minutes of flight time this afternoon. That figure includes ROG and climbing to about 300 feet for cruising at the Junior 60's famous "single speed".

I don't understand your maths here, David. Where does the 48 Watts total come from ?

Thread: Futaba Receivers - any alternatives ?
05/10/2018 12:35:43
Posted by Rich too on 05/10/2018 06:37:31:

The LMA recommend specific RC layout/systems for larger aircraft, why doesn't that apply to smaller aircraft?

Because it has no more weight than an opinion of one organisation.

Thread: TX talking to 2 RX's in different models at the same time?
04/10/2018 22:31:08
Posted by Bob Cotsford on 04/10/2018 11:14:21:

The receiver number is independant of the model number so it's possible to have two model definitions using the same receiver number. The latest version of OpenTX will warn you if you try to use a receiver number that's already in use, earlier versions didn't warn you.

Bob, if you simply copy a model to a spare slot, as I described in my last post & as Tiger's clubmate did, there's no warning that the same Rx number is now used by both copies.
The warning only appears if you try to change an existing Rx number to one already in use.

04/10/2018 20:38:01
Posted by TigerOC on 04/10/2018 10:11:13:

Just to clarify; this is the Frsky Taranis thread so I assume it's safe to assume I am talking about this equipment.

Oops, I read the OP via "latest posts" & didn't notice the it was an Frsky topic before replying. blush

When I'm creating a new model in my Taranis I often just copy a similar layout model to a spare model slot, change the Rx number & bind the new Rx then tailor the control throws etc to suit .

Of course if the Rx's are D8 mode there is no model match function.

Thread: The Accidental Lightning Pilot
03/10/2018 23:21:13

This link is a blog by Taffy Holden's grandson, I think the story in link in the OP was copied from this blog. But the blog also contains a Youtube video of Taffy during a visit with his family to Duxford to see Lightning XM135 in 2013 about 3 years before he passed away.

IMO this Youtube video is well worth watching.

Edited By PatMc on 03/10/2018 23:22:05

Thread: TX talking to 2 RX's in different models at the same time?
03/10/2018 22:58:24

Depends on if his gear has "model match" (or similar) or not. Or even if he has bound both Rx's to the same memory.

Thread: Funfly Electric Motor
03/10/2018 11:46:29

IMO Nigel's advised package is spot on, though if you have enough ground clearance for a bigger prop this 700kv version of the same motor would give better vertical at the expense of all out speed. BTW ignore the max power figures in both motor descriptions, they don't tally with the max current & voltage range.

The 4-Max motor has several disadvantages compared with both HK ones, it would only take be able to use 3s lipo for the same dia props (which means lower potential power) or, on 4s, would have to use a smaller prop to stay within current limits. Also the motor shaft is at the "wrong" end, requiring use of the bolt on prop driver which can be troublesome if it's are a fraction out of true centre & it means ensuring clearance for the 5mm shaft that's projecting into the firewall mount.

Thread: Futaba Receivers - any alternatives ?
02/10/2018 23:06:35
Posted by Erfolg on 02/10/2018 20:25:29:

John, not meant to be political, beyond stating how the EU operates.

No, you're stating how you think the EU works. sad

Thread: When modelling money saving goes too far...
02/10/2018 23:04:04
Posted by The Wright Stuff on 02/10/2018 09:20:16:

Visiting at the weekend, I couldn't help but notice streamers of used masking tape dangling from the ceiling. "It's expensive stuff", he enthused, "you can dry it out and use it over and over again"...

Sigh!

What does he do with used bog paper ? devil

Thread: Funfly Electric Motor
02/10/2018 23:00:35

Any of the motors in this HK page should be suitable, just a question of balancing a lower kv one with large dia prop for better climb rate or a a higher kv with smaller prop for speed.

Thread: Ebay sellers...
01/10/2018 19:17:51
Posted by Paul Marsh on 01/10/2018 19:04:23:

This person is in Cloud Cuckoo Land, wants £500 for a tatty airframe, which may go for £20 in a swapmeet. Says there is an engine for it, a valuable MDS!!! laugh

V4AAOSwGHdboVkO

Strange, question according to this thread it's in the proccess of being electrified.

Thread: Crow braking with a DX8
01/10/2018 11:24:53

My experience has been the same as Steve's, on very model I've used spoilerons (without coupled flaps) the nose has risen as the spoilerons have been deployed. The good thing about this is that if the model is going to land short when they're deployed you still maintain flying speed if the ailerons are dropped back to normal in order to stretch the glide.

Edited By PatMc on 01/10/2018 11:26:12

Thread: Transmitter Stick Length and Tension
30/09/2018 18:32:56

Back in the 1970's when model helis were a bit of a noveIty, I remember talking to a couple of guys who were competent FW flyers but just learning to fly helis. They reckoned that they found it easier when they'd removed the springs, dunno if they'd retained the ratchet on throttle.

Thread: Crow braking with a DX8
30/09/2018 18:14:18

Frank, IMO ail diff suppression only partialy restores aileron function, CAR is generally more effective. On a small aerobatic glider like the MT Lightning I wouldn't use ail diff anyway, it achieves little & slows the roll rate.

30/09/2018 16:59:10

David, spoilerons don't actually allow the model to slow down more than they would if not used, in fact they increase the stalling speed. However they do increase the descent rate and angle making it easier to land in a tight area. They also make the aileron function less effective, I always program for coupled ail + aprox 50% rudder (CAR) to switched in for the landing phase when I use them.

Thread: Turnigy SK3 3536 1050 rpm/v current rating confusion
29/09/2018 22:32:23

BEB, the price difference doesn't account for the differences in current & power ratings or a few other anomalies in the respective listings.

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