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Post  John Goddard Mon Feb 04, 2013 7:11 am

ian1954 wrote:Hi John,

Just a few suggestions

1. Try a "proper" head that will take a plug with an idle bar.
2. Show your age and revert to spark ignition.
3. Be British and run diesel.

lol!

Liking it Ian but the object of the exercise was to prove to myself that these old thangs could be made to
perform (nearly) as well as modern stuff.

It'll probably end up with something else made in America but 50 years later strapped to the front.
Glow current draw - Page 2 Pictur43


Although I did find myself perusing the Progress Airworks site last week....
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Post  fredvon4 Mon Feb 04, 2013 7:23 am

John this is heavy for your use but I see a lot of ways to reduce the weight and suck power from your on board RX batt

Better yet at less than $8 it is a fairly cheap item that could be used on any of you craft


This lightweight on-board glow driver unit is ideal for model aircraft, helicopters and cars and features an LED on/off switch, a voltage regulator and all leads. Simple to install, a push of the button will ignite your glow plug and keep it on for 15secs. The unit will automatically adjust the output current to ensure the best working temperature for the glow plug.
Although it featues an input voltage range from 6v-12v, and power can be taken from the RX power supply, a 2s Lipoly power supply is advised.
Spec:
6v~12v Auto Sensed input voltage
Constant output voltage 1.4v, 6A max output.
On/off switch, also auto shutdown after 15s.
Short Circuit and over-heat protection.
High efficiency switch mode BEC
LED on/off display.
Dimensions:
Weight: 22g (inc all leads & switch)
Dimensions (BEC): 32mm x 23mm x 7mm

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=14840
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Post  John Goddard Mon Feb 04, 2013 7:56 am

Yep that'd be great Fred we could certainly do away with the LED and most of that cabling BUT

a pal has one and it switches off after 15 seconds and we don't think it has an over ride.

It's a little porky too once we stick a 2s on it.
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Post  John Goddard Mon Feb 04, 2013 8:51 am

Dearest Darling
Remember I promised not to spend any more money on ebay for at least a month............
Embarassed

This should do it....
http://www.ebay.co.uk/itm/150971269903?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649
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Post  dirk gently Mon Feb 04, 2013 9:33 am

Actually, the leads' resistance does make a difference. I bought a glow clip with battery holder online, but I couldn't start any engine with it. Quick measurement showed that the voltage drop on the leads was about 0.6V, which only left 0.9V for the plug. I replaced the stock leads with shorter and thicker ones, and now it works without a problem.
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Post  dirk gently Mon Feb 04, 2013 9:46 am


Actually, I'm a little bit suspicious about this. Is it a voltage converter? It seems it's going to drain your battery dry very quick.

I'm just wondering - do you need to apply full voltage to it? If it's only to help the glow plug maintain the temperature, perhaps only 0.5 or 0.75V would be enough? this would roughly divide the weight of the battery 4 fold.

Also, I'm not sure, I don't think the glow plug is designed for being constantly fed with current. I may be wrong, but this may have adverse effects on the longevity of the plug.
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Post  ian1954 Mon Feb 04, 2013 10:19 am

So, let me think about this.

You are flying super duper loop the loops with a 50 year old engine where RC was an afterthought or makeshift change.

The throttling is done by restricting the exhaust but not changing the fuel metering.

Throttle back (term used loosely - bung up the exhaust) and the plug is effectively "flooded", "cooled beyond the point of no return" or "generally stuffed". Not being a diesel, a quick dive (I have seen it happen occasionally but not guaranteed) will not restart it.

I have burned many plugs by leaving the battery connected because I was too lazy to disconnect when bench running/running in.

Not having had much experience of RC HairyBatTricks, only three line control line stunt (third being throttle) - Similar issues encountered (even by using a pukka RC throttle). However, control line stunts have a limited duration - length of lines - and are fundementally 2D - up and down (How hard can it be?) - so it may not be directly comparable with a spinning loop.

It was solved by using an RC Plug with an idle bar before I returned to Diesel (Yes, PAW - would you like to borrow one. Still being produced and a more than 50 year old design!).

It may be worth trying a head conversion with the RC idle bar plug. You could always test it first.



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Post  John Goddard Mon Feb 04, 2013 10:41 am

I doubt I could ever be accused of doing things in the correct fashion
Guys but I usually get there eventually.
I think the 'challenge' is equally likely to be fuel starvation as the glow
Being extinguished. I kid you not, on full rates the rolls were as fast if
Not faster than any thing (many) that I've flown. Allied to that it climbed
V quickly to over 200 feet not sure how many C/l (non I imagine) would
Go straight up for so long/ bear in mind the tank is not pressurised.

Yep the throttle Ian is literally that, the ring strangling the motor.
I've got several other ideas as well.
You'll notice on Ithe vid where I had the idle whilst walking over the field
Was too fast to place on the deck without it zipping away which is why I
Trimmed it down (poss too far) and left it there. I've probably going to
Program an 'idle up' on one of the switches to prevent that as well.
As for burning plugs don't forget they burn because they're glowing too long
Too old or too much voltage. The plug itself doesn't know if it's glowing because of
Electrickery or catalytic reaction.
Very Happy
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Post  Surfer_kris Mon Feb 04, 2013 11:26 am

John Goddard wrote:P.S.
Just so we're clear guys this isn't to start the thing.
I'll do that with the flight panel and M/C battery.
This is just to give the glow a little help once in
The air and the needle valve is swamping the glow
With fuel at lower revs during 3d type manoeuvres.

Why not do what people do on larger engines?
You put a microswitch that is regulated mechanically by the throttle arm (a disk type works better) to engage a separate battery at low throttle settings only.
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Post  John Goddard Mon Feb 04, 2013 12:07 pm

2 words Kris.
Weight and complexity
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Post  Surfer_kris Mon Feb 04, 2013 12:13 pm

Well, you can't get everything. If you want to have glow power you'll need to carry extra power for it, and a microswitch is about as easy as it can get (saving the plug from burning out at high revs).
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Post  Admin Mon Feb 04, 2013 4:40 pm

I see others answered your main question. I meant to get back to you earlier. I didn't check the current with my multimeter as my D cells for the Cox battery box were dead and I didn't have any laying around.

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Post  John Goddard Tue Feb 05, 2013 4:54 am

OK
You may take turns to shout 'told you so'........!

A single AAA sort of glows for a huge 22 seconds

and

Fanfare

An AA for 1 min 20 seconds

I think there's a drawing board I need to return to some where.......
Embarassed
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Post  warrenlead Tue Feb 05, 2013 5:19 am

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Post  John Goddard Tue Feb 05, 2013 5:29 am

Cheers Warren
Very Happy
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Post  ian1954 Tue Feb 05, 2013 8:52 am

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