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Member postings for Nigel R

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

Thread: Spektrum Service UK
12/08/2020 09:20:32

That's nice and quick, well done Al's.

Thread: Painting glow engine blocks?
12/08/2020 09:06:22

Hi all

Perhaps someone has done this before.

I have several engines (some old style Irvine 46s and OS 46 SFs) I am tidying up as a bit of a background project. One or two of them have discoloured aluminium.

Has anyone used any paint, successfully, on engine blocks?

I did think initially of the usual automotive answer, Hammerite, but is it resistant to glow fuel?

Thanks!

Thread: Orange Rx
12/08/2020 08:41:20

None with Futaba, but three with Spektrum DSMX. Been faultless.

As above, I find them just right for foamies.

Thread: Aeromaster
12/08/2020 08:38:46

I got the legs mounted to the fuselage, then wrapped and soldered last night, before the muse left me:

20200811_221428.jpg

Then I watched the lightning storm for a bit. Quite spectacular, unusual for this country, clear sky between myself and the storm cloud which was some miles away; the sky was lit with continuous yet silent flashes.

Edited By Nigel R on 12/08/2020 08:39:23

11/08/2020 09:54:24

Never used GRP sheet before, must try some.

Made a start on the U/C:

20200810_222229.jpg

20200810_222248.jpg

Another job for the K&S bender.

I'm using an 8g rear leg and 10g front. As far as I could make out that was what the original Aeromaster used. My U/C has a little less height than the Aeromaster plan shows, but I am using bigger wheels, overall, should be the same, if my sums have come out right.

The next job there is to clamp the thing in place and get it wrapped and soldered, before cutting off excess lengths and dressing the axles with a washer and a flat for the collet. Then I can finalise the exhaust mounting bracket.

Thread: What has happened to i.c. engines?
10/08/2020 14:11:13
Posted by kc on 10/08/2020 14:04:03:

At first glance I thought the mention of thumbscrews was for the purpose of persuading the lawmakers to be sensible,

well now that's an entirely more entertaining prospect! devil

Thread: Aeromaster
10/08/2020 13:19:14

Whoops, nearly forgot. Sorted out control horns.

I like the SLEC "big" control horns. They have a decent size base, and a pair makes a good horn for closed loop. My "engineered" answer to attaching the things is a pair of M2 x 15mm bolts:

20200810_112851.jpg

With the elevator I just screw into the spruce joiner, and as usual add a drop of cyano to harden the threads up.

Thread: What has happened to i.c. engines?
10/08/2020 13:09:53
Posted by kc on 10/08/2020 13:01:32:

ic pilots could use the same hatch catches or magnets if they choose not to adulterate their model!

Apologies for continuing the thread drift.

Nylon thumbscrews hold wings on and require no tools to operate.

Sold at modelfixings, of course

 

Edited By Nigel R on 10/08/2020 13:10:50

10/08/2020 13:08:17
Posted by Barrie Lever on 07/08/2020 12:18:06:

The World is your Oyster.

Regards

Barrie

Well said.

Thread: Aeromaster
10/08/2020 09:16:58

Another grab bag of small jobs this week.

Just Engines did not have the turbo header in stock, so I ordered an OS header and a JE flex pipe, and opened out the cowling:

20200808_224447.jpg

20200808_224500.jpg

20200808_224518.jpg

JE also sent a neat metal bracket to hold the flex pipe at the rear, yet to be mounted as I want to get the U/C fitted first, don't want the two things fouling each other.

I also did some other cowling jobs, mainly opening up around the motor, and making needle valve access, plus started fuelproofing.

Then took a break from the front end, to get the tail end attached and lined up:

20200809_223909.jpg

That went fairly well. Need to do a touch of fettling around the front of those blocks, put some filler in at the tailplane/fin leading edge and get the control horns on.

Small steps forward.

Thread: Biplane build required
06/08/2020 14:32:09

Simple answer - no struts!

06/08/2020 14:01:04

I'm aiming for just three wing bolts and one servo plug on my current build. I think that's probably an ok level of faff.

I did consider going with elastic bands for the wings, they're also low on faff.

Thread: How much have you spent on modeling in 2020?
06/08/2020 13:57:33

Twenty quid a week would cover my normal outgoings, fuel & build costs, etc. I keep track of the major outgoings, big lumps like a TX or engine, because, household budget and all that - there have been none this year.

Bought a couple of second hand four strokes and sold some two strokes that I am unlikely to use (with more to sell yet) as the writing's now sadly on the wall for the two strokes at our club site * probably a net zero there.

* PS still looking for a second 40 surpass if anyone is selling.

Thread: Is this Power Supply Suitable?
06/08/2020 13:14:28

Just to further muddy the waters, I have had two 4 button chargers (both from one well known UK electric flight supplier) both with built in 80W AC supplies.

Both were supplied with a very poorly made and undersized PSUs which failed. The units claimed to be 80W but having seen branded laptop 50W supplies which were far larger and heavier I struggle to believe the claims on the PSU. And these were not particularly cheap units.

With a quality branded laptop supply they continued functioning... until the output FETs failed (catastrophically) in one case, and on the other, the screen or CPU died...

Thread: Biplane build required
06/08/2020 08:34:48

Airmeister...

**LINK**

Thread: Is this Power Supply Suitable?
06/08/2020 08:33:17
Posted by Steve J on 06/08/2020 08:30:45:
Posted by EarlyBird on 06/08/2020 07:07:26:

Because of this example I have come to the conclusion that the forum should not advocate using any equipment in a way and for a purpose for which it was not intended. Simply because there are people out there who are a danger to themselves.

I am glad that my ancestors didn't adopt this philosophy. "You be careful with that sharp rock!" "Why do you have to burn up your meat on the fire?"

PS Society of Model Aircraft Engineers ring any bells?

Trick is to take small enough steps each time that failure is a manageable quantity.

With some folks, diving right in with mains electricity... maybe not a 'small enough step'.

06/08/2020 08:31:03
Posted by EarlyBird on 06/08/2020 07:07:26:

This is a perfect example of someone with little knowledge, one assumes, selling what can only be described as a dangerous open framed PSU.

Seems perfectly compliant with most of its local regulations! devil

Thread: Use Venturi effect for cooling air?
06/08/2020 08:17:51
Posted by Richard Clark 2 on 05/08/2020 16:59:17:
Posted by Nigel R on 05/08/2020 11:10:17:
Posted by Richard Clark 2 on 05/08/2020 03:30:44:

Unlike an IC engine an electric motor and the ESC should run no more than 'warm' as the efficiency is greatly reduced if it is hot. You are not trying to make a room heater.

And carrying that heat away with a strong airflow merely 'disguises' the heat caused inefficiency as the motor is still generating the heat you are carrying away.

So if the motor and/or the ESC is getting hot enough to need a lot of cooling you should look at the suitability of the motor, the prop size, the number of cells relevant to the prop size, and so on rather than trying to improve the cooling.

 

I'll keep an open mind.

I have several questions:

1) Can you explain how an ESC efficiency drops with temperature?

2) Can you explain how a strong airflow "disguises" this proposed inefficiency?

3) Can you explain why "number of cells relevant to the prop size" is a measurement worth investigating?

4) Can you explain why the power train design should be assumed to be at fault?

Here goes. I have numbered your questionw so it's simple to connect question and answer.

1) Unless 'superconducting' (Google is your friend) every electrical circuit has 'resistance' to the passage of electricity. This means the circuit wastes some of the electrical in heating itself which i not what you want.

2) The inefficiency is not "proposed", it is real and measurable. Having hopefully accepted 1 above it follows that passing the generated heat along to something else, in this instance the air has not stopped this heat being generated in the first place.

3) Given a fixed voltage (number of cells) and full throttle a given prop will cause a fixed load on the motor. You can s reduce this load (and thus heat) by using a smaller prop or less cells. And vice-versa of course.

4) It's not a fault it's the laws of the universe (as so far discovered). Some people understand them better than others so designs vary in competence.

Edited By Richard Clark 2 on 05/08/2020 17:18:25

hi richard

1) hasn't answered the temperature related efficiency question

I mean, I'll state my POV; heat relates to power relates to I2R(approximately, because reactance etc), so at any given sensibly sized ESC the current will not affect junction temperature within ESC until a point on that curve where the power dissipation begins to rise rapidly due to nature of second order curve. Maybe you have a more sophisticated understanding, hardware isn't my speciality.

2) hasn't answered why you say it 'disguises' the inefficiency

Again, my POV, you just need to cool the device a certain amount. If you need X amount of cooling - in our case facilitated by airflow - to maintain a low enough junction temp that your ESC operates "efficiently" then, well, er, so what? Airflow isn't disguising anything; it is just a means of achieving an end. Again, maybe you can help me understand what I'm missing here, but this is the basic process the hardware guys at my work operate with.

3) ok - but that means that the ESC isn't sized correctly for the current

4) ok - but again means that the ESC isn't sized correctly for the current

Your example in the second post appears to concur with my reply to 3 & 4 above, as things relate to the ESC, ignoring the motor aspect of your setup.

Edited By Nigel R on 06/08/2020 08:19:41

05/08/2020 16:23:46

"Cooling does not impact on the ESC's working efficiency for a given duty"

Well, given that if you force cool the device it's junction temperature will drop thus leading to reduced drain/source resistance, I would disagree, but I was rather hoping for richard to explain his 'efficiency is greatly reduced' and 'disguises inefficiencies' statements, and why any of that meant examining the surrounding powertrain would be needed.

05/08/2020 13:55:02

I believe you'll be more than ok with what you already have. Just make sure the air must go right by the motor and the ESC. Battery is less important. You may need the odd baffle around motor or ESC.

I have a very similar powertrain on a 3547 size motor (not the one I posted earlier in thread) putting out 750W (ish).

The inlet is a narrow scoop by prop on underside of cowl area.

A slot in firewall allows air through. The ESC is right behind the slot.

The outlet is a simple square hole in fuselage, not even a ramp on this one.

Hope that helps.

BTW the Wayfarer is a nice looking design.

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