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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: backwards engine running
26/03/2010 14:07:52
The fuel lines were inside the rocker cover because that was where the Lister had it's injectors.
 
A failed turbo induction-side oil seal is also a known cause of diesel engine run-away.
Thread: Demonstrating 2.4 ghz video downlinks at shows
25/03/2010 19:52:20
Clive,
 I don’t think so,
N=10log(10)*P(i)/P(ii)dB
 But then I could never count.
 When you mention 'antenna focus' are you referring to directivity or resonance?
25/03/2010 11:33:12
Timbo,
 I thought your installation would be robust.
 I wonder what modulation protocol is used for downlink?
It seems almost impossibly dirty, does it have type approval?
 I wonder if the downlink problem arises at the point before spreading and immediately after dispreading. If so, then thorough screening might be an option.
 Although the best option would be to bin it before Eric Bray finds out.
 (See his thread on the campaign for EMC).
Erfolg,
What does it mean?
 As a very loose comparison.
You are standing at a locked door outside a room.
 If you have the key can enter.
The room is hostile, standing upright presents an easy target but you have a very small 'footprint'(narrowband), by lying down (spreading) you become a small target but have a large 'footprint '(wideband).
 You can cross the room unseen by laying down and crawling.
 At the other side is a door, if you have the key you can exit the room and stand up safely (despreading).
 And yes, your world is in peril.
24/03/2010 20:24:01
How is this happening?
I've no experience of using a Video link, but if I may out of curiosity..
The video signal is 10mW=10db.
 The spread spectrum signal is 10mW =10db.
The RC spread signal uses a very wide frequency band, the width determined by the processing gain. The processing gain can be the region of 60db or expressed as a ratio of power  gain 1,000,000.
Wanted signals can be in the noise (10mW video signal unwanted) and the wanted signal should still be received, the unwanted signals are not seen.
The wanted signal/code is recognised/seen by the receiver and the data retrieved and processed by despreading.
How close was the receiver to the video transmitter and was it electrically isolated from the rest of the equipment?
Thread: Glow to Petrol Conversion.
23/03/2010 15:17:20
Martin,
I too had a misspent youth tuning Bonnies Nortons etc.
Recalling from memory initial trial settings were….
Methanol at 11:1 38 degree adv. Methanol at 13:1 34 degree adv
100 Octane 10:1 38 degree adv.
Not sure if this has any relavence on the current conversions.
23/03/2010 12:13:19
Believe me guys, a centre drill will do the job.
 If you must use a milling cutter a slot drill is better than an end mill.
An end mill is a profiling tool.
Also I remain to be convinced on the need to fit head shims but watch with interest.
Thread: backwards engine running
23/03/2010 11:56:02
Martin,
 Fully agree.  
An urban/rural myth.
Gardner even specified a range of optional fuel pump governor springs to compensate for altitude running to maintain output power.
Thread: Glow to Petrol Conversion.
23/03/2010 10:42:02
Doug,
Start the hole off with a small centre drill (Cronos or RDG tools) guaranteed not to wander if you take it steady and cheaper than a prop driver.
You can also get the magnets from ‘guysmagnets.com’  £3.61 for 20 post free. He also sells from ebay.
Thread: backwards engine running
23/03/2010 10:23:04
As posted above, I also fail to see how a 4 stroke glow engine is able to maintain reverse running.
I have heard several stories over the years of Diesel engines, automotive, marine and stationary, running backwards. Also of stationary engines installed in engine/generator sheds where the air vents became blocked and the running engine caused the shed to implode.
The problem I have with automotive/marine engines, perhaps I'm missing something, if the injection timing was advanced enough to 'back-rock' the engine then surly the timing in the reverse direction would be so retarded that the compression temperature would be insufficient to combust the fuel.
 Perhaps the long stroke of a Gardiner engine and its relative piston speed could maintain revolutions for a period.
The two stroke diesel, (certainly the TS3 (as mentioned above) and also the Napier Deltic) that utilised a blower(supercharger) for scavenging could only run in the 'forward' direction.
Thread: Age Profile Survey - the Results!
23/03/2010 08:11:35

Perhaps the under 16s are just not interested in surveys.

Thread: Glow to Petrol Conversion.
23/03/2010 08:02:02
Doug,
Just reposition the magnet (or fit another) on the driver to give the correct timing. Remove the original if fitting a new magnet.
As stated earlier, Neodymium fumes are toxic so take care if drilling the old one out. They are also very brittle.
Thread: backwards engine running
22/03/2010 18:50:02
Reversing Dynastarts were also fitted to marine outboard engines. Oil contamination of the brush gear and CB points tended to be problem, usually at the most inopportune moment as I recall.
Thread: Cox .049
20/03/2010 20:08:54

 
It works but the response is rather slow.
Closer lapping of the ‘barrel’ may improve things.
Might try a mark2 version sometime.

Thread: The April 2010 issue
15/03/2010 14:02:26
The tone of the article surprised me. Not what we, as readers, are accustomed to from the Magazine.
Thread: Glow to Petrol Conversion.
15/03/2010 13:55:03
Watching with interest.
A few comments if I may..

Doug, What about a small centre drill to start it off?

Mixture..At ¾ turn out thats not much oil per rev, almost a drought in the crankcase of a conventional 4 stroke.
 Gerry, Are you using synthetic oil or 2-stroke oil in the petrol mix?
 There is probably quite a fine line between insufficient oil for the bearings and an excess of oil clogging the exhaust valve stem if using the 2-stroke oil.
The compression pressure requirements for glow and petrol are quite close and if necessary retarding the ignition slightly for a test run rather than stripping out the engine and adding shim gaskets might be worth a try even on a new engine.
Satisfactory air/fuel(petrol) ratios for the ignition of 4 strokes seem easier to achieve than for a 2 stroke.
While it may be safe to reduce the oil content of a 2 stroke a 4 stroke will need a close eye kept.
Doug, Some before and after results on the new engine would be useful, also any ignition advance/RPM data would come in handy if possible.
Thread: Wankel engines
14/03/2010 14:32:50
The only common sense thing to do is to fit a proper engine in the Cessna and then send the Wankel off to me.
Thread: Diesel v Glow
12/03/2010 13:02:39
The actual ignition point of the CI engine is determined by temperature/pressure of the gas/mixture and our throttled engine controls the ability of the port to pass gas/mixture by combining the area opened with the elapsed time between opening and closing of the port, the 'time-area integral', ie. the point of maximum pressure/temperature within the cylinder is dependant on throttle position.
 Volume, pressure and temperature of the gas all change at the same time. The laws of Boyle and Charles are combined.
P(i)*V(i) / T(i) = P(ii)*V(ii) /T(ii)

Probably getting in to deep again.
12/03/2010 11:01:42
  Taking that the velocity of the gas through the port is to the piston speed as the bore area is to the port area. I assume that SPI is more effective in boosting long stroke engine performance 
 V (gas): S (piston speed)=D squared (bore): d squared (port).
Touching on ignition timing/compression radios and taking into account the above. On a throttled engine the ignition timing will be proportionate to compression pressures. ie. proportionate to the effective port diameter.
 All things being equal, if the compression screw is set for max RPM at full throttle then the engine should be responsive to the throttle and adjust its own ignition point/RPM accordingly.
 Currently, I only have two CI engines, a rather tired PAW 55BR RC that is happier running at full chat than throttled. The other is a home build. Neither have SPI (although inspired by this thread I may file the home build piston skirt and give it a go).

 

Thread: Engine use to charge flight batteries
11/03/2010 14:45:02

You just need to couple  a second brushless motor between the main brushless motor and the prop and wire it into the flight pack as a three-phase alternator.
 If you ignore efficiency losses you will have perpetual motion.
Thread: Diesel v Glow
11/03/2010 14:37:58
SPI increases the time available for induction by combining the areas open during the induction elapse time.
The more powerful engine at 1/16 confirms that SPI does work, there are sceptics.
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