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Member postings for GrahamWh

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

Thread: Warbird engine start-ups
17/12/2014 09:47:07

Thanks Tom, that was great.

Thread: Four stroke crankcase venting
13/12/2014 17:26:59

You are probably right Phil. But the weather is no good for flying so the tinkering itch gets stronger until it has to be scratched!

Gonzo, I did notice that reference in the text on the Just Engines site from which I bought the engine, thanks for the link. I thought that perhaps there was some clever timing involved rather than just fancy advertising, but in reality having opened it up when I replaced the bearings recently I saw that the nipple is set into a hole near the top of the camshaft chamber which is always open to the rest of the crankcase, so no special timing. Indeed when the prop is pushed round it breathes in the same way as the old surpass and the ASP FS61.

I will update this thread after testing the engine so others may learn from my mistakes, or success as appropriate!

Interesting ideas re the reed valves in a twin Bert. I wonder if it's been done before. I noticed an ad in a 70's or 80's mag for a four stroke with a cambelt and thought that was weird, then saw recently another manufacturer is doing that again!

13/12/2014 09:57:51

Phil the modification just makes the ASP70 run the same was as the OS 70 surpass I have. The oil bypassing the piston ring will lubricate the bottom end in the same way that the surpass does, and all the four strokes before this crankcase-inlet manifold link was introduced. Indeed, some sizes of the ASP four strokes still use the old system.

12/12/2014 22:25:17

I have had another thought on the venting issue. Considering the venting on my ASP70 in which the crankcase is vented to the inlet manifold, then I think what is happening during the 4 strokes of the piston is as follows:

1. Compression stroke, piston going up, vent sucking fresh mixture from intake manifold and into crankcase. (Of course there isn't such thing as suction - it's atmospheric pressure pushing the other way etc...)

2. Power stroke, piston down, vent expelling mixture from crankcase into intake manifold but can't go to inlet as valve closed, so is forced down through carb the wrong way, and out into the surroundings - WASTED FUEL.

3. Exhaust stroke, piston up, vent sucking fresh mixture from intake manifold and into crankcase (same as in 1)

4. Intake stroke, piston down, vent expelling mixture into intake manifold, mixture being sucked into cylinder head via open intake valve, any short fall (due to compression of mix in crankcase) being met by production of fresh mixture from carb.

(The above is not giving much thought to the mixture's compressibility and its effect may depend on engine speed.)

Anyway, I had been considering the effects of fuel mix in the engine causing rust, but I now realize there is a real possibility of fuel waste in the power stroke.

I have changed my ASP70. I've removed the vent nipple on the inlet manifold and blocked the hole with a small bolt and fiber washer and am venting the crankcase to the air. For the last 6 months I have found that a 6 min flight leaves me with half a tank of fuel. I shall see over the next month or so (if weather allows!) if the new arrangement saves fuel. Of course I'll have to re-set the mixture screws to get the engine running right after this adjustment, but I'll fly the same flight pattern at about the same speeds and report back.

 

 

Edited By GrahamWh on 12/12/2014 22:26:48

Thread: Has anyone else noticed the site being extra slow?
22/11/2014 21:11:02

Thanks Ken - I get it now.

Maybe site speed depends on number of users? Fast for me again now - 21:10 Saturday

19/11/2014 20:15:43

Oh dear, since reading this then posting I am eating my words - the site is now slow - every time I click on a link it takes ages to load up the new page!

Watched kettle and all that?

Edited By GrahamWh on 19/11/2014 20:16:58

19/11/2014 19:54:52

Been fine here, though I have had a problem with my computer being slow generally. Solved it by altering firewall settings to not allow explorer.exe (not internet explorer) from connecting to the internet. Rogue programs seem to like using windows explorer to link to t'net in the background bringing other stuff to a crawl. Everything fine since then. Might be worth a try Robin. I'm using internet explorer.

Ken - what does the ..ne.. stand for in your signature, I've never understood that bit?

Thread: 4 stroke throwing prop
18/11/2014 19:15:54

I would add when you check that there is not a build up of carbon in the head, also check that the cylinder head shim is still there. If it isn't replace it as the compression would have been too high.

Thread: motor cools down gets stiff then is ok see note
16/11/2014 17:18:04

I get a similar effect with my electric planes when I disconnect the battery from the esc. Although they are set to have the brake off, the prop is stiff to turn for some time. If I disconnect the leads from the esc to the motor, the prop is fine again. It seems the esc still has enough charge in it's capacitors to think, and decides it is now going to provide breaking - even though it is no longer connected to the battery! Very strange, but I assure you it happens!

Thread: What are your special model flying moments from 2014?
13/11/2014 22:49:49

Taking my son to Weston Park show, next would be maidening my Flair pup.

Thread: First Radio
13/11/2014 22:46:28

I think the most common radio at the club I go to is the DX6i. Learners and very experienced fliers use it. There's a couple of 7's and 8's and even some old 35MHz jobs! One guy has a Taranis - it keeps chattering to him.

Thread: Wiring for a one battery set-up
12/11/2014 16:44:22

If the leads from the battery to the ESCs are long you will need to add capacitors at the recommended intervals (I think every 20cm but this may not be right). If you don't, the capacitors on the escs may burn out due to high ripple currents in these wires. I think it is 3000uF you have to use, rated above your battery voltage (say 50v to be safe), but you'd need to check by searching this forum or t'net.

Thread: The heat can do damage!
09/11/2014 20:06:00

I hardly ever check for warpage. Just don't think of that - thanks ZK.

Thread: Glue advise
09/11/2014 16:41:33

I did one with epoxy and waterproofed it with some epoxy resin I had for a canoe project. It is very strong, the finish looks like varnish yet the epoxy did not swell the grain in the ply wood like varnish would have done (varnish would therefore have needed 2 or 3 coats to get smooth).

Thread: very new
08/11/2014 21:43:56

I would suggest you don't bother with any transmitter that is not programmable - expo is very useful for taming any plane. The DX6i is available by itself for around £80 (search on google), and compatible receivers such as the Orange DSM types for around £10 (Hobby King). Also make sure it is 2.4 GHz - it cannot interfere with other models that way.

I got my son a cheaper transmitter but regretted it, he needed expo to steady his trainer. I ended up getting him a DX6i and we sold the other on ebay. Some of the guys in the club who have been flying for decades use the DX6i, so it is a tranny that will do you for more advanced models too. There are other good cheapish ones too, but I would recommend you only get programmable ones - you may regret it otherwise in a few months or so.

 

Edited By GrahamWh on 08/11/2014 21:52:32

Thread: Flycatcher
08/11/2014 21:35:42

Linds, would it not need more down thrust rather than less with the motor as a pusher so the line of thrust runs closer to the centre of drag? A bit like the Hobby King Bixler and other high engine pushers?

Edited By GrahamWh on 08/11/2014 21:54:12

Thread: Brian Taylor 71" Mossie electric conversion?
07/11/2014 10:37:14

You may need to put smoothing capacitors in the leads from the batteries to the ESCs in that case John at whatever the recommended distances are - every 20cm?

Thread: Four stroke crankcase venting
06/11/2014 13:19:10

Thank you for the various replies chaps. I can imagine a very long breather pipe causing some reduction as power as the piston tries to go up and down for a normally vented engine, but making a short tube and having it go into a larger diameter one with an unsealed union would overcome this.

For me the issue is the fuel getting into the crankcase as the piston goes up. I disagree with your view Shaunie that fuel would not be sucked in - as the piston goes up the pressure in the crankcase would I think be below atmospheric, and as the inlet valve would be closed the pressure in the carb and inlet manifold will be returning to atmospheric, so there wouId be fuel mixture pasing into the link tubing to the crankcase in the ASP's system. I may try converting the ASP temporarily by blocking the inlet manifold hole with a suitable small bolt and venting the crankcase breather. Has anyone actually done this conversion on a four stroke with the crankcase breather connected to the inlet manifold?

Edited By GrahamWh on 06/11/2014 13:29:32

Thread: Motorcycle transportable model
06/11/2014 13:07:37

With a 2 piece wing (as one end of each wing is bigger than the other) a box could be built that would house the front of a fuse and the widest ends of the wings, with the rear of the fuse and the tips halves of the wings poking out the back, and the box could be strapped to the rear of the seat or a luggage rack/pannier. The box could be lined with foam suitably cut away to safely hold the front parts securely.

There would be room for a few lipos so a small (50"?) electric plane would be okay.

Thread: Am I jinxed?
05/11/2014 18:43:15

Sorry to hear that Steve. Time to get a TV and DVD player sorted for the bedroom then.

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