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Member postings for Simon Chaddock

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

Thread: Nostalgia
09/08/2008 02:06:00

I have the advantage that I don't have to rely on my memory. As soon as I go into the roof I will post some pictures of an original box, the plan (remember the little monogram in the shape of an aerofoil - Albert E Hatful?) and a complete original.

And I am STILL a little lad - in my head.

06/08/2008 22:47:00

Eric

In the 40's it would not have been an AOP9 - that was the last variant (1955 on) and was quite a bit different from the earlier AOP6. The war time Austers (1 to 5) were classified as liaison and observation aircraft.  The Auster 5 (a Lycoming engine) was built in the largest numbers and appeared in the civil market as the Auster Arrow as immortalised in the KK rubber powered scale kit of which I must have built dozens!

Why do the old have so much of useless information?   

Thread: Dead stick
06/08/2008 21:47:00
Without engine power there is a strict limit to the amount you can use the stick to control the plane, (particularly up!) hence the term "dead stick".
Thread: OS 26 going dead stick
06/08/2008 09:38:00

Hello Ted

"About 5 minutes" is a long time for something like an air leak or wrong mixture to take effect, so I agree with Simon that fuel shortage is the more likely cause.

How full is the tank after a dead stick? Remember when you are actually in the air (unlike  when on the ground) the fuel is sloshing about a bit so the clunk can be temporarily exposed with still quite a bit of fuel remaining. In addition at low throttle it will only take a couple of miss fires for the engine to slow down so  much that it stops.

I assume the OS is mounted conventionally in your Junior 60, upright & sticking out in the breeze? Is the position of the fuel tank OK relative to the carb?

Simon 

Thread: The August Grand Prize Draw
06/08/2008 00:49:00
Yes please - I have all the required bits ready & waiting.
Thread: The 5cc found!
06/08/2008 00:34:00

Hi

Yes Brian the effect is the similar with both coils but rather worse with the Gettig. Not surprisingly the spark with the Gettig is a bit weaker and thus more sensitive to a plug "wet"with excess fuel. The massive automotive coil sparked the tiny plug come what may! The advance /retard requirements are similar for both.

The whole carb body is a single piece - actually several machined parts but all bonded together with Redux aluminium glue! Only the needle, throttle barrel and float chamber are removable. 

I hope to make the new exhaust from 10mm annealed copper pipe as it needs a very small radius bend as it leaves the cylinder head. The existing pipes were fabricated from thin steel sheet formed into two halves and brazed along the seams. A technique well beyond my level of skill! 

03/08/2008 22:50:00

Hi

Things have been moving a bit slowly - house painting takes priority. It appears that my efforts to control the oil consumption have made the 5cc rather sensitive, you can set the needle to either to run nicely at low throttle( measured at 2450 rpm) or at full power and to make matters worse, starting requires a completely different setting.

The best starting method found so far uses the old motorcycle trick of flooding the carb by "tickling" the float but this really only works well when the engine is cold.

Today was the first run using the Gettig coil with 3 NiCd cells but before any more running I will have to add a silencer, not quite so easy with the bifucated exhaust. What would be nice would be some fancy pipes around each side of the head (a bit like those on the Bristol Centaurus!) joining into a silencer behind.

We shall see. 

Thread: Lubricating gear box
30/07/2008 16:48:00

Don't panic about a gearbox and a can motor.  Properly made thay can be much more efficient than 35%! It could even come close to the efficiency of a brushless unit, particularly if the motor & gear box are well matched to the prop. Remember its the overall efficiency - watts in to thrust - that actually matters.

Good gear teeth don't actually rub, they simply "roll" over each other so only light lubrication is required.

As for the extra volts of the Lipo I doubt if it will make a great deal of difference (carbon brushes always arc) so just use full power carefully. A 480 might indeed overload the gear box unless it was designed to take the load. 

Thread: Yesterday take offs today landings!!!
28/07/2008 23:25:00

Andy

Not to dampen your sprits too much but the addiction to flying has a down side. Sooner or later your blog will read "Crashed today!". It happens to us all but learn from it and you will find the addiction gets you going again. 

Thread: confusion
26/07/2008 00:39:00

Never mind Newtons Laws, flying has much more to do with Sod's laws:-

 "If it can - it will"

 "If it hasn't - it will soon"

 "If it has - tough!"

Thread: The 5cc found!
22/07/2008 23:10:00

I now have my Gettig HT coil.

/sites/3/images/member_albums/31957/S2400019.JPG


It is indeed very small and light but it has no indication as to which connection is which.

I assume the solder tags at each end are from the LT coil and the centre one is the HT. I guess the HT winding should show a higher resistance that the LT one.

Anyone any ideas?

Thread: Model 4 Stroke lubrication
19/07/2008 23:58:00

I believe this system could be applied to almost any 4 stroke, it just needs a new/modified back plate. I appreciate this might be beyond many users but it would be quite easy for the original manufacturers. Installation should not be a problem, two bit sof neoprene tubing and a small tank and with oil coating the cylinder walls UNDER the piston, leaner mixtures would no longer be the same hazard to engine life.

Well thats my theory.

As far as I know the contact points on the 5cc are tungsten. 

Thread: Electric Vulcan
18/07/2008 22:08:00
Not a great Depron fan myself but I bet going from 48" to 80" span has made it easier to mould the 3mm skin to the double curves. It will be one impressive model.
Thread: Model 4 Stroke lubrication
18/07/2008 21:40:00

Brian

As it was an example of 4 stroke lubrication I thought it was appropriate here.

Although the 5cc has additional components to provide positive lubrication to the main bearing, I believe just sucking oil into the crankcase and then blowing it back out could be applied quite easily to any 4 stroke with a fairly simple modification to the back plate. I am sure such a system would provide better lubrication than relying on oil in the fuel. An oil tank with a "clunk" feed could work for "full house" aerobatics.

I will post the new video of it running on '5cc found'.

The Gettig coil is quite a bit smaller, but just as expensive, apparently it only weighs 2.2 ounces. I hope it produces enough spark!

18/07/2008 16:42:00

This is the 5cc with a "flight" oil tank. Feed from the bottom, return to top. It holds about 20cc of oil. Note how the back plate has been repositioned with the return at the bottom of the crankcase (see earlier post). I have a miniature HT coil on order from Gettig in the USA and as soon as it arrives I will post a video of the engine running in its full flight configuration and its max RPM with my new photo tachometer!

http://www.modelflying.co.uk/sites/3/images/member_albums/31957/OiltankB.jpg

17/07/2008 17:22:00

Oily fumes are fine to lubricate things but just how many oily fumes will come out of a 4 stroke crankcase breather when the engine is only lubricated by oil in the fuel?

Maybe a bit of oil should be put in the crankcase before each flight. If it was vented only from the rocker cover(s) it would ensure oily fumes came up the pushrod tubes & you could do away with the oil in the fuel!

Just an idea. 

Fuel/oil is for two strokes! 

16/07/2008 22:36:00

Don't worry too muchPete.

It only takes a minute amount of oil to lubricate things adequately and the movement of the push rods and rockers is small and lightly loaded when compared to the main and big end bearings. Compared to full size, the total hours a model engine will be run is relatively small. As long as you don't damage it in a crash a good 4 stroke should out last a model several times over. The positive lubrication on the 5cc is a luxury as the engine was intended to run reliably for 24 hours non stop.

Thread: Very strange 747
16/07/2008 09:30:00

There was a proposal to re-engine the B52s with 4 big turbo fans in place of the current 8. I did wonder if that odd 747 was a mock up of a counter proposal to make use of the redundant B52 engines!!!!

Thread: Stripped plug thread
16/07/2008 01:05:00

Hi Shades

Helicoils are made in small sizes but you will also need the appropriate special tap to cut the new thread. It is larger diameter but the same thread pitch as the original. The helicoil is then scewed in with a special tool and it locks itself in place. The glow plug is screwed into the helicoil.

Neat and effective but I don't know if a helicoil & tap is made for a standard glow plug thread.

You could try a motor cycle repair shop. Stripping threads in aluminium bike engines is quite common so they usually have helicoil kits. 

Thread: Soft or Hard Brake ?
14/07/2008 11:45:00

Gary

Landing any higher performance glider needs a bit of skill.  They tend to fly so well that actually getting down at the point of your choosing is difficult. Pointing at the ground does no good as it just speeds up, unless you have some form of air brake which you can use as a "negative" throttle. Power right off but prop turning will certainly act as an air brake but remember it only takes a small amount of power for the prop to "keep up" with the air flow so that it will have little or no braking effect. You should only actually stop the prop when you want to glide as far (or as fast) as possible. 

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