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Member postings for Dickw

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

Thread: Unisens-E Graupner telemetry sensor
05/07/2017 15:04:40

Both the SM lead and the Jeti lead mentioned in the instructions are USB to serial conversion leads - i.e. there are electronics in them. The others probably are as well, so you need more than a USB lead (modified or otherwise).

Where abouts are you based? There are several options for connecting leads in the instructions so you may be able to borrow one locally to do the update.

Dick

05/07/2017 13:33:51

According to the UniSens-E instructions it should be possible to connect it to a PC using a variety of third party cables including the "Graupner USB interface no. 7168.6"

Section 11.1 of the instructions details options and how to.

Have you found the English instructions:- https://www.sm-modellbau.de/Bedienungsanleitungen

Dick

Edited By Dickw on 05/07/2017 13:37:06

Thread: Balancing two lipos in series.
29/06/2017 14:20:58
Posted by Braddock, VC on 29/06/2017 09:45:36:

Last night, after finished charging, battery voltages were as follows:- goosed battery 8.39, other battery, (after a quick spin of the starter to see what the revs were like) 7.71.

This morning voltages were 8.34 and 7.71 respectively.

Looking at these voltages suggests that the "goosed" battery is fully charged, and the other battery is nearly flat.

Your discharge capacity values seem to confirm this.

Looks like the problem might be in the charging - are the balance leads OK on both?

Dick

Thread: Volunteer Pilots Required
27/06/2017 10:05:27

It sounds fun but I don't have a model with a buddy-box radio and I already have a prior engagement that day. However, this post will at least keep it at the top of the latest posts list.

hope the day goes well Brian.

Dick

Thread: create a 9s
25/06/2017 12:28:58

Once you go over 6s finding an ESC can be a problem, but there are many available if you look hard enough. They are often labelled "HV" as well as giving the cell numbers.

Using 5s plus 4s to make a 9s pack is OK, and I have several such packs myself, but it is best to match the capacity and C rating of the packs to avoid problems.

Dick

Thread: Use of ailerons for braking.
13/06/2017 12:55:50

With a heavy 2 servo 2m wing soarer I use ailerons up at about 45 degrees to act as spoilers for landing. Having both ailerons up reduces the chance of tip stall and allows a much slower, nose up, high drag approach. You will need to use some elevator compensation but if this can be added with a mixer then you can foget about that after a few experiments.

Experiment high up ( 2 mistakes high!) to start with so you can judge the elevator compensation required and to find out if you still have effective alieron control. If you can reduce, or reverse, aileron differential while the ailerons are up that will help with lateral control.

Dick

Thread: Prop Size Selection
24/05/2017 16:28:21

Seems a reasonable approach at first glance, but once you get beyond a 9,9 x 9.9 the extra numbers could get a bit unwieldy.

Anyone for a 185220?

Dick

Thread: What kv?
24/05/2017 16:06:47

There isn't really a simple way so it comes down to experience and or motor calculation software.

Your 2500kv motor will try to turn at 18,500 nominal on 2s but to get anywhere near 18,000 rpm on a 7x5 prop would need in excess of 200 watts, so at least 30 amps on 2s, once the plane had gained speed in flight. Static it would probably be closer to 40 amps.

Not sure if your 1818 is up to that.

Turning a prop faster requires more power so if you used a 4800 kv motor you would be well in excess of 100amps on 2s before your 7x5 prop got anywhere near 30,000 rpm. Some racing competition classes run props at 35,000 rpm but the props are specials designed for those rpms.

You need to pick a kv so that the motor can reach around 80% of the nominal rpm on your chosen prop and battery volts. If you want about 10 amps on a 7x5 and 2s then try something like a 1600 kv motor weighing about 20 to 25 gms.

Dick

Thread: Prop Size Selection
24/05/2017 12:48:30

He does mean 4 inches and not 4 degrees.

A 6040 is a normal 6x4 etc.

Dick

Edited By Dickw on 24/05/2017 12:54:40

Thread: ESC or Motor issue? Pulsing, stuttering?
22/05/2017 10:00:47
Posted by Keith Newman on 21/05/2017 20:10:29: .........

Mega Motor 22/30/2 Brushless Motor
Saker 80amp ESC
4s 3200mAh Lipo
APC Electric 10 x 6 Prop

Anyhow, i forgot to test it with a 'watt-meter'
.............

I used to use that motor in an RC combat model with an 80A Hyperion ESC. It would pull in excess of 60 amps static and around 40 to 50 amps in flight on a 3s Lipo and a 9x5 prop.

I think 4s and a 10x6 is pushing it a bit.

I think there was originally a different version of this motor available with a lower kV (1770), but the current spec is here and the cell numbers mostly refer to NimH cells.

Dick

Edited By Dickw on 22/05/2017 10:02:32

Edited By Dickw on 22/05/2017 10:03:46

Thread: Operational Guide, All Models and Radio Control
13/05/2017 10:36:22
Posted by Capt Kremen on 12/05/2017 23:21:24:

Everyone so far ... YES, you are all quoting the (exact) texts that I'm reading from too but just where is the document entitled 'Operational Guide, All Models and Radio Control' that keeps being referred to?

If it is not a specific stand-alone document, then why is it inferred as such?

........

'Operational Guide, All Models and Radio Control'

As others have pointed out, this is in what is just a summary check list following up the main document, and these words are intended to refer to specific sections of the Members Handbook.

I don’t think it has caused any confusion in the past, but I agree it could be written better and now that it has been pointed out it probably will be updated.

I went to our BMFA Area meeting this week on behalf of my club and we were informed that a new Members Handbook will be issued very soon, so it may be prudent to wait and see if the section headings change before changing any references to them.

Dick

Thread: Where is the heatsink?
11/05/2017 10:54:06

You don't say what ESC you are using, but I do have some ESCs where the flat label side is indeed a heatsink.

In your case it sounds like the ESC is rated OK for the power of the motor, but the BEC circuit is struggling to meet the power requirements of the servos. You could try a cooling airflow over the label area and see if that helps. Alternatively a separate BEC or an ESC with a higher rated BEC might be needed.

Dick

Thread: Binding Spektrum RX's
07/05/2017 10:26:14

Chris

You can bind multiple Rx to the sme model memory and use at the same time, but the Rxs need to be the same types, i.e same protocol and data rates. I don't think the number of channels is an issue unless that affects the Rx "type" regarding the other factors

It is a common issue in the F5B comps I fly where 2 Rx are required - one in the air and one on the ground.

Dick

Thread: How to connect a solenoid to a receiver?
04/05/2017 14:32:55
Posted by Sam Taylor 1 on 04/05/2017 12:34:58:

Dick, that is the exact one I've got! I bought it because I needed a 6V pull action solenoid. I had no idea that it was a 'latching type' with complicated wiring.

​I haven't yet proved that the solenoid actually works. Connecting the pos. and neg. terminals of the battery and the solenoid does nothing, and connecting to the pos. of the battery to the neg. of the solenoid and vice versa does nothing either. I don't know very much about electronics, but I know that just connecting the solenoid to the battery won't make it work.

The purpose of the solenoid is to hold back a latch. When the solenoid pulls in the latch is released, letting the glider wings fold out. Because of the radial force, I picked a solenoid rather than a linear servo. If there are pull action servos, which can withstand some radial force then this could be a suitable option.

Sam

It should work when connected to the battery.

Red wire to battery positive and black to battery negative for a few seconds should make it move one way.

Black wire to battery positive and red wire to battery negative for a few seconds should make it move the other way.

If you leave it connected too long it could overheat and burn out.

Dick

04/05/2017 14:27:19
Posted by Ben B on 04/05/2017 13:24:47:

The Dr Mad Thrust switch would activate anything up to 12W so should be fine for a solenoid but as said your latching solenoid requires a relay circuit to swap the voltages. You'ld need a Dual pole dual throw switch

......

In your installation the "motor" would be replaced by the solenoid and you would switch the battery supply to "A" using the radio switch.

Unfortunately this solenoid is designed for short pulse operation only. It seems to be 5W power on 6v supply, and if I read the data sheet correctly that limits it to a max pulse length of 1 minute.

It looks like Sam might need an ON/OFF momentary switch as well as polarity reversal.

Dick

04/05/2017 12:14:38

Sam

I think what you have is this "latching" solenoid, and the instructions for it are here.

This device seems to require a single pulse to move it to a locked position, and a reversed polarity pulse to move it back again. That is going to need more than a simple RC switch to operate. Any ideas anyone?

Dick

Gary beat me to it!

Edited By Dickw on 04/05/2017 12:15:14

04/05/2017 11:09:04
Posted by Sam Taylor 1 on 04/05/2017 10:54:20:

I was under the impression that without a switching circuit of any sort, the solenoid won't move when I touch the red and black wires to the pos. and neg. terminals of the RX channel I want to use?

The pos and neg terminals on the RX are permanently energised, so should power your solenoid. Does the solenoid work if you connect the red and black wires to a battery? If so, it shoukld also work on the pos and neg of the RX.

Thr RC Switch comes with a connection diagram - a copy here.

Dick

Thread: Warbird Replicas Spitfire LF mk IXc
29/04/2017 18:19:22

opps, double post!

Edited By Dickw on 29/04/2017 18:19:48

29/04/2017 18:18:43
Posted by onetenor on 28/04/2017 19:13:56:

What a wonderful experience .I would love to do it too butt couldn't afford it .Apart from which my O.W. would divorce me if i spent that much money on what she would probably call my "Stupid Hobby " well done that man . John

I am very lucky because it was actually my wife who came up with the idea, researched it, arranged it, and paid for it as a present for a special birthday (not my 21st unfortunately!).

Many thanks everyone else for your good wishes and offers of support. I will post here again when I eventually get going. I don't anticipate any problems with the build, but the finish is a different matter and there are so many great photos in this thread I might be ashamed to show mine.

Dick

28/04/2017 10:37:47

It is a long time since I attempted a scale model so this is almost a new venture for me, but I have just collected a Spitfire kit from Warbirds. The plan is to try and replicate MJ627 which was converted post war into a 2 seat trainer version and is now based at Biggin Hill.

I want to build it in the 2 seat version because that is me sitting in the back seat in the photo, taken when I had the great good fortune to have a flight last year.

Richard has already supplied me with some extra parts, a special set of decals, and lots of good advice, so failure in the attempt will be entirely down to me.

I am in no rush and will probably build it over the winter, so don't expect any immediate updates, but wish me luck.

Dick

20160920_144328.jpg

Edited By Dickw on 28/04/2017 10:44:07

Edited By Dickw on 28/04/2017 10:44:35

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