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Member postings for Brian Parker

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

Thread: Extending leads - battery or ESC?
06/04/2012 20:46:20

Is not the problem one of impedance?

We have a lot going on in the input side of the circuit.

Capacitive Reactance reduces with frequency whilst the equivalent series resistance (ESR) of the capacitor increases with frequency. By increasing the cable length we are now altering the inductive reactance.

Our circuit contains capacitance, inductance and resistance (ie impedance) all opposing current flow.

The capacitor is the weakest link.

Glen your luck could run out.frown

Thread: Woo who (3)
13/02/2012 16:20:13
Peter,
Ford produced a special jig to enable accurate grinding of the valve stems if the clearance needed increasing. The stem was mushroomed and if I recall correctly ran directly on the cam, not via a tappet.
Problem was that the split guides were easily knocked out from the top using the special tool but not quite so easily refitted from below.
I believe the early V8 engines used the same method.
Very crude by today’s standards.
I was introduced to motor vehicles at a very early age….all so long ago….but what a variety!
13/02/2012 13:37:25
Adjusting the tappets’ goes back to the time when the valve clearances on many side valve engines were set by means of an adjustable tappet type cam follower, the adjusted tappet acting directly on the valve.
A true cam follower is shaped to accurately follow the cam profile. A flat faced ‘cam follower’ is a tappet.
To be pedantic, you can only adjust tappets when you have an engine with adjustable tappets otherwise you just set the valve clearances.
It could be a lot worse, how about a single cell battery.
Thread: Woo who?
18/11/2011 14:21:28
Even if we can’t agree on the correct spelling for Carburetter/ Carburettor, it’s necessary to distinguish between Mass and Weight.
Consider this, If a can of fuel of mass ‘M’ is suspended on a spring balance in a true free falling aircraft the spring balance will record zero weight, the fuel is apparently weightless.
Thread: Anyone point me at a kit or plan for an Avro 504 - .60FS motor?
06/11/2011 18:18:29
Thanks Steve,
I’ve had a look at your Blog and I am following Mick Knights build in M.E.
06/11/2011 12:14:29
Steve,
That’s 547 components left to go before you start tapping 10 and 12 BA.
It could go up.
I’ve Eric Whittles build notes and also have had the A1 size drawings from Hemingways for some time but lack the courage to make a start.
Good luck with the project.
06/11/2011 09:00:50
Candidate for the Whittle V8 perhaps?

Edited By Brian Parker on 06/11/2011 09:06:41

Thread: 6EXA 35mhz.
11/10/2011 12:31:19
Thanks Guys, after reading this thread and looking at the hack modules on the Giant Cod site I have resurrected a Futaba 6EXAP.
The 35MHz 6EX had a RF fault and was gathering dust under the bench.
I decided to test the 2.4GHz FrSky V8 conversion (hack) module.
It (and a receiver) arrived this morning. Just 3 cables to disable, 3 wires to solder and 2 holes to drill. Half an hour later and after binding to the FrSky receiver, a successful range test was completed.
Just need it to stop raining for a flight test.
The instruction sheet states CE compliance.
I’m a Sprektrum convert but If you are on 35MHz with a Futaba 6EX then at £11.55 for the module and with receivers starting at £10.78 then this is a budget way into 2.4GHz.
Thread: Jittery 35meg set
03/10/2011 19:46:17
The transmitter has a RF/ modulation fault.
Check the crystal holder’s soldered joints and associated PCB tracts.
A couple of years ago I was gifted a faulty 6EX that produced similar results.
The RF was not as modulating as expected when tested.
Couldn’t correct the fault.
 
It’s still under the bench gathering dust.
Thread: Is balancing all that necessary?
14/09/2011 20:13:49
Efrolg,
I actually said that an out of balance prop will have a detrimental effect on the engine. We are in agreement.
14/09/2011 19:30:11
It doesn’t matter where you position an out -of -balance prop in relation to TDC, it’s still an out of balance prop and will have some slight detrimental effect on the rotational balance of the engine.
Vibration in single cylinder engines is caused by the inertia of the accelerating reciprocating parts (piston ,rings, gudgeon pin and the top half of the connecting rod). The only way to truly balance a single cylinder engine is to neutralise by introducing equal and opposite reciprocating forces.
This is not practical, so a balance factor is used (as a compromise) when calculating the counter balance weight to achieve smoothness at the most appropriate RPM.
Thread: TT 54 propeller thread is anticlockwise to unscrew!
10/09/2011 16:39:23
Peter,
Yes, I was not denying the harmful effects of detonation and have indeed seen pistons from petrol engines with holes in their crowns.
10/09/2011 10:50:42
Peter,
In full sized engines, the ignition process is influenced (smoothed) by slower moving (cooler) boundary-layer gasses.
Under certain rare conditions are these boundary layers absent from small glow engines
Also at maximum rpm a degree of valve bounce is probably influencing the process.
09/09/2011 19:46:08
All interesting stuff.
But, as I understand it.
Detonation in an IC engine occurs after the normal ignition point, creating localised uncontrolled high pressure pockets around the combustion chamber, the piston is already on its downward journey.
This causes the engine to ‘ knock ‘ (this is actually the engine resonating or ‘ringing’ but will not stop the engine unless it is so severe as to destroy the engine.
An engine at high rpm will not detonate simply because there is insufficient time for it to take place.
Pre-ignition is the ignition of the fuel before the normal ignition point and can take place if the engine combustion chamber is severely overheated.
This will cause the engine to run even hotter and could stop the engine and possibly to even run backwards instead of stopping .

Edited By Brian Parker on 09/09/2011 19:46:26

08/09/2011 20:34:13
For a locknut to work correctly the locknut (outer nut) must be torqued against the inner nut at a higher torque than the inner nut is torqued to the prop.
For plain hex nuts, the locknut should be thinner than the main nut in order to effectively ‘lock’ the threads.
It will not loosen.
You won’t get sufficient torque using an adjustable spanner only ‘gashed’ knuckles and a rounded nut.
Thread: Hobby Lathe
12/08/2011 12:53:45
Actually I understand that the Myford name, drawings, rights etc. and most spares have been acquired by RDG tools of Hebden Bridge, Halifax.
The end of an era and the beginning of a new.
Thread: heat treating aluminium
25/07/2011 21:03:00
Tim, just let it age.
Most common aluminium alloys will temper/harden if left for a period of days.
But maintaining it at just above 100 degrees for a few hours will speed the ageing process to a few hours.
23/07/2011 20:52:52

Depends, but this has worked in the past..
Harden by boiling in a pressure cooker (above 115 degrees) for five hours.
Or try age hardening by resting for 5 days (the aluminium that is, not you).
Thread: Engine stops in negative G
20/07/2011 12:04:14
Noticed this thread.
It reminded me of Beatrice ‘Tilly’ Shilling OBE.
‘Tilly’ developed what was officially known as the R.A.E. ‘restrictor’ and thus solved the problem of the early SU carburettor equipped Merlin engine cutting out under negative ‘g’.
‘Tilly’ and her team travelled around the WW2 bases fitting the restrictor. This restrictor was universally (and unofficially) affectionately known as ‘Miss Shilling’s orifice’.
Tilly apparently was quite a character, she lapped Brooklands at over 100mph on her racing Norton and worked on the Blue Streak missile, but her attitude to the ‘Establishment’ prevented her reaching high office.
Tilly died in 1990.
Thread: Loverrly legs
07/07/2011 19:40:57
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