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Author Topic: 1/8 scale hydroplane 'Atlas van Lines' build  (Read 41323 times)

martno1fan

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #25 on: July 19, 2009, 04:38:43 PM »

Yea stinger drives are ok for easy adjusting but from what im told the strut is still the best for speed  ok2.That said the extended type are suposed to be very good compaired to the standard ones.
Mart
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Ramon

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #26 on: July 20, 2009, 10:37:23 PM »

Hi  again guys, finally found a bit of time to put on a further update.

Following on the lower sponson skinning was finished off before turning it back on the jig and taking stock of the insides. Lots of clamps need for this as well as weights as you can see but it all went well. Glue used is Titebond 3 - this has been used for the entire build except the engine area. Excellent glue, very quick grab time, but not easy to sand.





Back on the jig it was time to establish the fuel tanks and radio gear. The tanks are made from SWMBO'S hair 'stuff' aerosols. Marked 200ml they actually hold 250ml each. I got the caps off using a crude cutter piercing the top in stages. I had previously tried prising it off but this left the top distorted and flimsy. A couple of ally caps were turned and fitted with brass nipples. The feed system is the R/H tank is pressure fed from the exhaust, clunk weight in R/H side feeding to the L/H tank then clunk weight pick up for the engine feed. This was based on info gleaned off the forum and the guys at the lake. My main concern was that tanks from tinplate may rust on the inside and though I have made countless tanks over the years for aircraft have never had this problem. However I have had - despite intense cleaning methods - residue of flux turn to wax like deposits that will clog the needle valve with annoying ease. Thing was those tanks were easily removed to sort the problem out and these weren't going to be hence the choice of 'drawn ally' aerosols. These 250ml were the largest I could get in the available space so how long an OPS-60 at full chat will last on half a litre remains to be seen. 







The ally caps are glued on using 'JB Weld' and the tanks are held at this point, supported in the middle by a band of insulating tape and 1/32 ply and at the rear by a button of 'silicone' May be a bit overkill but they're in there for the duration so wanted to be sure. At first the tanks were going to be totally 'buried' but I have decided to make small hatches over the front ends to access the nipples so these at least can be 'got at' for cleaning if neccessary.

The radio gear sits in front of the engine - weight in front of the C/G - with the rudder servo remote in another box aft, the servo lead running through the black tube seen on the earlier pics.
This was done as an effort to reduce the weight at the rear and to give a short and rigid pushrod to the rudder.

A little bit more then a bit later!

Mart - it is going to have transom mounted strut but with the prop close in - about 11/4" overhang. This is how the drawing is set up. However - having followed a lengthy discussion on this matter on R/C Universe provision has been made to retro mount the strut brackets inside the strut coming through the bottom skin. This would give a submerged drive with the prop position just under the transom.

I can still use the flex shaft for both - obviousy I will have to shorten it but the angles involved look very close to each other. Remember chaps I have no idea how these thoughts will pan out this side of things is my steep learning curve but I am going to enjoy myself doing it - Andy, You can't wait to see it goooo have a guess how I feel.

Ian, I notice I made a complete boo boo :embarrassed:
Quote
Again I think I have looked at this from an aircraft perspective - to counteract torque the side thrust is normally set to the left.
I did mean the aircraft turns left with torque - side thrust to the right - dyslexic brain again

Bye for now - Ramon

BTW I have not forsaken the Huntsman. It's just that the weather has not been suitable for spraying enabling me to make quite a bit of progress on this one :-))
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ids987

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #27 on: July 23, 2009, 03:29:30 PM »


Ian, I notice I made a complete boo boo :embarrassed:I did mean the aircraft turns left with torque - side thrust to the right - dyslexic brain again

Hi Ramon, Maybe you could think of it as an aircraft with a pusher prop  :}


These 250ml were the largest I could get in the available space so how long an OPS-60 at full chat will last on half a litre remains to be seen. 

I'm thinking 5 - 10 minutes ballpark.....

Ian
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Ramon

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #28 on: July 23, 2009, 04:26:11 PM »

Really - REALLY ? is that each bottle?? Hell I've lead a sheltered life - my OS 35 aerobatic models would do a seven minute flight on 90cc and that was running rich!!!! {-)

Seriously I didn't expect much - I can't remember how big a tank I used all those years ago but it was home made. Memory says (hmmmm?) it lasted a lot longer so must have been quite a bit larger. I was only using the X type Graupner props in those days - guess the revs are much higher now eh?

That said at this stage I am only intending to get the best out of this on straight running - just seeing it go will be buzz enough.

Thanks Ian - should have thought of the pusher - nice one

Ramon
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andyn

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #29 on: July 23, 2009, 04:52:07 PM »

Yep I'm afraid so, mind you at least you don't run multi's, in three quarters of an hour a 3.5cc will drink 1.5 litres, a 7.5cc will drink 2.5 litres, and a 15cc will drink 3.5 litres. thats about 20 a race for a 15...
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ids987

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #30 on: July 23, 2009, 05:06:11 PM »

Really - REALLY ? is that each bottle?? Hell I've lead a sheltered life - my OS 35 aerobatic models would do a seven minute flight on 90cc and that was running rich!!!! {-)

Hi Ramon, My CMB 45 uses at least 2 litres in 1/2 hour. I think the OPS 60 should burn slightly less, but not that much less.
I seem to remember that my old OPS 60 used to go about 20 minutes on 1 litre. That was in a mono, but before I found a pipe that worked properly with it. RPM and load make a difference. Pipe pressure tends to waste a bit of fuel - unless you use an interim tank for the pressure, as it can atomise fuel out of the tank and blow it out of the exhaust, but sometimes it's needed. Nitro makes a difference. More nitro = richer mixture.
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Ramon

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #31 on: July 23, 2009, 11:40:15 PM »

Well that's it then - back to rubber power free flight models it is !!!!!!!!!! ok2

No, not really but I can see this is going to use a lot more fuel 'per go' than I've been used to up to now!

Quote
..........unless you use an interim tank for the pressure, as it can atomise fuel out of the tank ...............

Would you mind explaining this a bit more in depth Ian please. Pressure fed fuel is a new method of fuel feed to me - I never had much success with it with the type of aircraft I flew but the engines had good suction with relatively much smaller venturi's so very rarely required it.

Following on from my last post on the fuel tanks themselves and Mart's comment about using  ally 'drinks containers' - I have had an email from someone following the thread to say that a friend of his had had touble with the fuel reacting with the ally and causing gumming up resulting in damaging a K&B 67. I replied that I thought it might be a coating that may be applied being disolved by the nitro. Just a thought. Yesterday I saw one of these bottles for the first time and and confirm that that it did have such a coating. I did check the aerosols leaving 5% fuel in them for some time as well as cellulose thinners neither seeming to have any effect but I do think if these (drinks cans) are used this is a warning that should be given due consideration.


Here are another few pics bringing the build closer to its current status




These shows the front end and rear radio gear box positions. The central ply plate at the front is removeable. I intend to bolt lead weights to this as a trimming aid if the C/G needs to be adjusted.


Here is the set up at the stern. The strut brackets will be shortened (to the line just visible) and redrilled, the ply plate insert is reinforcing if it's decided to later mount the strut from underneath


All the stringers are in place and the insides epoxy coated. The blue foam is from Marts idea of using 'pool noodles'. It's near ready for those top skins.

That's it for tonight - thanks as always for your input - Ramon


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mook

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #32 on: July 24, 2009, 11:04:03 AM »

I'm loving this build     O0   ;D
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andyn

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #33 on: July 24, 2009, 01:12:41 PM »

Pressure feeding is basically using the pressure from the pipe to pressurise the fuel tanks. This keeps the flow going to the engine. To do it with your tanks, you would have to take the pressure pipe via silicon tubing to the top tube on one of the tanks, then the lower on that tank to the upper on the other tank, then the lower pipe on the second tank to the engine. What I'm hoping to eventually do with my 3.5cc multi is to use a Novarossi Exhaust Cooler, which supposedly cools down the exhaust gasses travelling into the tank, which should increase run times. Might be worth a try on this thing too.

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ids987

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #34 on: July 24, 2009, 01:31:24 PM »

Pressure feeding is basically using the pressure from the pipe to pressurise the fuel tanks. This keeps the flow going to the engine. To do it with your tanks, you would have to take the pressure pipe via silicon tubing to the top tube on one of the tanks, then the lower on that tank to the upper on the other tank, then the lower pipe on the second tank to the engine.

Hi Andy, I could be wrong, but I think Ramon knows what pressure feeding is, and how it works. I think he was asking me to explain what I meant by a pressure tank.

Hi Ramon,

Following on from the scenario Andy has described, and in the case of your install, a pressure tank would be a third - small fuel tank. This tank is left empty. You connect the pressure feed from your tuned pipe (I hope you're using one ?) to the vent tube of the pressure tank. The pickup side of the pressure tank connects to the vent tube of your first tank. The idea is; when you go from full throttle to part throttle, the pressure in the tank is temporarily higher than the pressure in the exhaust. If there is fuel around the vent pipe area, it can be blown back to and out of the exhaust. Similarly with any fuel atomised from the main tank to the exhaust. With a pressure tank in between, the fuel passing backwards will just collect in the pressure tank - until the pressure pushes it back to the main tank (through the fuel pickup of the pressure tank). Hope I've explained that well enough. Let me know if not, and I'll try to do better.
My OPS 60 was a bit iffy running on suction feed alone. Coupled with the fact that you are planning to cross-feed from tank to tank, I think you will need to use pressure feed one way or the other. Of course, in a cross-feed install, the first tank becomes a pressure tank once it has emptied into the second tank......

Ian
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ids987

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #35 on: July 24, 2009, 01:52:43 PM »

Hi Ramon,

With regards to the fuel and containers, I did wonder about aluminium and nitro. If anything in the fuel is going to cause corrosion, it is usually nitro, or at least its by-product - nitric acid. It will eat through brass pickup tubes in fuel tanks - given time. Usually that is minimised by draining tanks after play.
I guess coated cans add another variable. If the coating doesn't even go "tacky" after exposure, I guess it will most likely be ok....
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Ramon

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #36 on: July 24, 2009, 10:49:27 PM »

Hi  Ian - yes got that and can see exactly what you are saying. :-)) I don't suppose this 'chamber' has to be too big so will fit something in the system. This is a new concept to me - the pressure feed I have 'dabbled' with unsuccessfully in the past was in search of obtaining a good consistent engine run throughout a flight. It is accepted that the key to a good aerobatic model is the need for a motor that is totally consistent. This is not top end performance - most engines (all glow two stroke that is) were run on the ground just off the 'break' into the 'two stoke' rev band. (Technically incorrect the rich running with the needle out from it's max setting was always referred to as four stroking.)  Hence the term [good 'four-two' run] characteristics of some engines.
Tanks played an important part in trying to obtain this consistancy and most were run on a 'uniflow' basis. Some (including myself) did  try to 'improve' this using pressure but without much success. Very much a 'horses for courses' situation. My first experience of pressure feed goes back to Army days! - 1967 when I bought in Singapore a Super Tigre G15 'speed' motor - enormous venturi fitted with a plastic insert for suction feed - but even with this it would only run using pressure.
The engine will have a tuned pipe though regretably not an OPS original. I was recently given a 60 size pipe by someone who was a keen R/C aerobatic flyer (BIG difference from control line I might add) Whether this pipe will be suitable to get the best from the engine I don't know but at this early stage it will have to act as simple 'exhaust chamber' at the least. Perhaps when the boat is up and running I will search out something more suitable if it proves otherwise.
Couple of pics here, perhaps you would cast your eye over them and tell me what you think. The red lines show positions of three baffles. (You cannot see through the pipe end to end).



That nitro is corrosive is without a doubt but I was always under the impression that the acid (nitric) is as a result of the combustion. The more I think about this the more - when you consider the mount of ally that comes into contact with the fuel in most setups - pipework?, filters, engine itself - that I would think the real culprit in this gumming up is something like the coating
reacting/dissolving as already said. It's very unlikely that I shall use anything more than 5% - 10 at the very most.

Thanks again Ian and for your help too Andy it's all grist etc.
Glad you are enjoying it Mook.

Regards - Ramon
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martno1fan

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #37 on: July 27, 2009, 07:01:59 PM »

Ramon i thought you might like to see this  :-)).
Mart
http://vimeo.com/4157234

http://vimeo.com/4156979
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Ramon

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #38 on: July 27, 2009, 07:58:05 PM »

Ah Mart, you really are a wind up merchant!!  ;)

Just tried again to download Flash Player again but still to no avail  {:-{- I get right through the installation process until it says - if installation is successful you can see the video above (or something very similar to that ) No video! just two white squares with the small red crosses in them.  Tried the trouble shooting and followed that through but still can't get these files to open - just keeps telling me to install Flash Player! So - I still can't watch it - Dammmmm! Keep it on hold for me - I'm just going to have to get this bl---y thing fixed!!!!

Got the rear hatch done today and the fins mounted - it's getting there. The weather looks abysmal for painting the Huntsman for the next few days so I'll stick with the hydro - at this rate it'll be finished first.

Any comments on that tuned pipe I've been given anyone - is it going to be suitable? What effect will the long parallel part have?

Regards for now - Ramon
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martno1fan

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #39 on: July 28, 2009, 12:41:57 PM »

OOPS forgot you couldn't watch these links  %),might have to do you another dvd sometime lol.Sorry i cant help with the pipe thing im not a nitro guy to be honest.Im hoping to get some hardware installed onto my hydro soon and then ill swap the motor from the wooden zipp and try it in her to see how she compairs.I have a few hulls to build before that so it might take me a few weeks till shes ready.
Mart
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ids987

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #40 on: July 28, 2009, 04:47:09 PM »

Hi Ramon,

Sorry, haven't had the opportunity to write on here for a few days.

I think you are right - in that (at least in our applications), nitric acid will only be liberated in significant quantities under combustion.
I have definitely experienced more than one fuel tank though - where the brass fuel pickup has corroded to the extent that it pulls up more air than fuel. Not sure whether that is the corrosive effect of the nitro itself, or the nitric acid passed back via the pressure feed. I would agree that this probably has little to do with the gumming up though.

With regards to the Hattori type pipes. Are those the ones where the end of the divergent cone is closed by a flat disc - with the stinger in the middle - rather than a convergent cone ?
I haven't used that kind of pipe myself, but I believe they work. I suspect they would be more peaky than conventional pipes, and therefore possibly unusable on engines with very high timing. The OPS is milder than a lot of modern engines though, so it may be ok. The OPS pipes themselves work ok, but are not the bee all and end all, and even the OPS "quiet" pipes are not at all quiet by todays standards. Here again though, the OPS engines probably have a bit less tendency to noise generation than some.

Pressure feed in boats was also (I think), introduced to try and aid in getting a consistent mixture and running. In some situations, it does help to give a more consistent top end mixture than suction feed, but can make throttling problematic. It seems to be carb dependent, and probably on how quickly the pressure falls off after closing the throttle. But hey, hydros aren't meant to go slow are they ?
In the world of multi racing now, almost everyone who wants to be competitive runs a float chamber. Don't think I've ever heard of one in a hydro though.

Keep it coming !

Ian








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ids987

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #41 on: July 30, 2009, 06:13:04 PM »

Hi Ramon,

Sorry, thought I'd better post back as I appear to have been talking rubbish in my last post. I also failed to read / interpret your questions properly.
I think it's fairly evident that the pipe in the photo is not the kind of pipe I was thinking of.

I'm pretty sure that the pipe itself will be a conventional dual cone type of pipe. The long parallel section is mostly silencer. The plates you have marked are silencer baffle plates behind the end of the pipe itself. Kind of like this (c/o Dave Marles / Prestwich) - except that your silencer section is wider, and extends from the join between the divergent and convergent cones:





The front / divergent cone of the pipe appears to be quite long, so it is likely to be best suited to an engine with relatively mild timing (an engine with shortish exhaust -> transfer blowdown period - favouring torque / reliability over out and out power / RPM). Very much what you would want from an engine / pipe combination in an aerobatic model - not that I know much about those. It probably won't get the very best out of the OPS, but it should work to some extent. The perforated plate silencers can work quite well, but it depends on the implementation. If the holes (or the total area of the holes) are / is too small (and I have seen / owned some which are), and the pipe presents too much back pressure, much of the function of the pipe will be dictated by the silencer.

Ian
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ids987

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #42 on: July 30, 2009, 06:22:34 PM »

Duplicate post...
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Ramon

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #43 on: July 30, 2009, 09:13:03 PM »

Ian, - just seen your posts - again many thanks, will digest and come back to you a bit later

Ramon
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Ramon

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #44 on: July 30, 2009, 11:11:32 PM »

Hi again,
Not sure where to begin here Ian, my knowledge of pipes is so limited. Beyond the basic working principle it's all so much a mystery. It seeems to me that the variables are so great - timing - nitro - torque band - revs - etc etc it's difficult to even comprehend where to begin!

However let's take the pipe in question. Sorry I can't provide a sketch but I'll do my best to describe it :-

Looking in the inlet end there is no convergent cone but a flat plate baffle with a central hole about 1/2" diam. Beyond that is another flat baffle with an offset hole that has a tube - as far as I can tell about an inch long - pushed through it. That's as far as can be seen from that end. From the outlet end again another flat baffle with another offset hole and another piece of tube this time about 1-1/2" long. The divergent and convergent cones are separated by a parallel tube approx 6-1/2" long with the first baffle positioned approx 3" past the limit of the divergent cone and the distance between the two outer baffles about 2"

I think I understand what you are saying regarding timing - the aerobatic engine would definitely be more set up for max torque at lower rev banding so from that I think that it's unlikely this pipe will act as little more than an expansion chamber.

As said this was donated by a well meaning friend and at this stage will have to suffice in the short term until something more suitable can be obtained (especially as I've just milled a posy clamp to hold it on with!) However if anyone out there reading this has a redundant OPS60 pipe or something simarly suitable lurking under the bench that they would consider parting with I would be most pleased to hear from them.

Not much done on the boat though the fins are now finished and fixed - having a couple of days getting the metal work sorted and a short break on bits for rebuilding that other OPS.

Thanks for your time again Ian
Back soon
Regards - Ramon

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ids987

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #45 on: July 31, 2009, 02:31:50 PM »

Hi Ramon,

Aahhh, my initial guess/assumption about the pipe design was actually correct.
The flat plate with the 1/2" hole in the middle functionally replaces the convergent cone. Everything behind that is basically the silencer. The convergent cone which you see is the end of the silencer section. It does not function in the same way as the convergent cone in a conventional tuned pipe.
The long front cone still suggests the same thing as in my last post (as does the intended application of the pipe) - that it is designed for use with a relatively mildly timed engine - which will tend to have a broad power band.
Going back to the other end of the pipe, the convergent cone in a conventional pipe acts as a reflector - reflecting the pressure wave back towards the engine. As it reflects the wave from different points along the cone, it tends to "blur" the arrival of the pressure wave back at the engine - spreading it over a longer duration. This, in turn, has the effect of broadening the powerband slightly. Replacing the cone with a flat plate, will tend to strengthen, but concentrate the reflected wave - giving a bit more of a kick when the pipe comes in, but across a narrower powerband. As our example "mild" engine will generally not come on pipe very hard, this may well give it a bit of a useful boost.
I won't waffle any more on my theories as to why (unless you want me to), but on the whole, I don't think the engine and pipe combination will have the best synergy, but there is always an element of "suck it and see" in tuned pipe selection.
The silencer section sounds fairly conventional. The pipes you described - linking the expansion chambers, may either be open ended, or closed at the end with radial perforations along the length. Either way, the functional model is not too dissimilar to the perforated plate example in the photo I posted. The main objective is to lose as much of the sonic energy as possible - by allowing the gas to expand, breaking the direct (straight through) path, and making it change direction several times - without posing too much resistance to the actual throughflow of the gases. I suspect that it will be substantially quieter than a good few pipes I've seen / owned / still own.

Ian
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Ramon

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #46 on: August 01, 2009, 08:26:49 PM »

Well Ian, just goes to prove you learn something every day. I would never have considered that the baffle would act as the convergent cone.

Thanks for your PM but (typically for me) replied in the wong manner so had it sent back today.  :embarrassed:
Sent you another tonight so hope you get that ok.

Still waiting for a decent break in the weather to get some paint on the Huntsman so have continued making parts for the OPS. Nearly there on that so will update the thread in a day or so.

Thanks for taking the time to explain things again. I for one wouldn't mind some expansion on the subject - I don't feel that that would be exactly off topic just a slight, albeit relevant, digression.
I think I understand the principle and also think I can see how the wave lengths attune to a certain point in the rev band but how do you know where and when? How do you choose a pipe for instance other than eg 60-90 size. Wouldn't this have to be more specific to an engines performance rather than capacity? Aaagh! so many questions for this well worn brain to cope with. %%

Regards - Ramon
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Ramon

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #47 on: August 02, 2009, 11:28:51 PM »

Hi guys, Not much to report on the hydro but as I was tinkering with the OPS bits today I was musing - as you do - on past posts regarding pressure feed.

Ian, your comment
Quote
In the world of multi racing now, almost everyone who wants to be competitive runs a float chamber.

If the float chamber works as I imagine - exhaust pressurises fuel tank, chamber fills up, float rises and momentarilly cuts off supply, engine draws fuel, float drops then cycle repeats - Surely the pressure on the fuel is cut off from the engine by the float chamber. If this is the case is not the engine then working on suction? or does the F/Ch act as as kind of pressure regulator ''allowing a bit of pressure through'' each time. With the large bores of the carbs on these type of engines I would have thought that suction feed alone would be difficult to maintain.

Just a thought - ??????????         

Regards - Ramon                         
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andyn

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #48 on: August 03, 2009, 11:55:47 AM »

The main fuel tank is pressurised from the exhaust and this forces fuel into the float chamber. When the fuel reaches a preset height, the float valve maintains that fuel height until the main fuel tank is empty.

Float chambers are great, there's nothing to go wrong in them %)
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ids987

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Re: 1/8 scale hydroplane 'Atlas van Lines' build
« Reply #49 on: August 04, 2009, 12:44:37 PM »

Hi guys, Not much to report on the hydro but as I was tinkering with the OPS bits today I was musing - as you do - on past posts regarding pressure feed.

Ian, your comment
If the float chamber works as I imagine - exhaust pressurises fuel tank, chamber fills up, float rises and momentarilly cuts off supply, engine draws fuel, float drops then cycle repeats - Surely the pressure on the fuel is cut off from the engine by the float chamber. If this is the case is not the engine then working on suction? or does the F/Ch act as as kind of pressure regulator ''allowing a bit of pressure through'' each time. With the large bores of the carbs on these type of engines I would have thought that suction feed alone would be difficult to maintain.

Just a thought - ??????????         

Regards - Ramon 
                        

Hi Ramon,

That is exactly what it does. usually you set the height so that the fuel is about level with the spraybar - what you might call a neutral position. The main point is that it gives a consistent mixture. Because it changes very little, you adjust the needle accordingly. Without a float chamber, there is a tendency to run rich in parts of the course - and lean in others. Add to that the overall level change from full to empty. You then have to try and set the mixture so that it never goes lean - meaning that it spends a lot of the time running rich. Smaller tanks will not be as susceptible to this, but with big tanks, it is a real problem. Both the moving mass of fuel, and also the level change between full and empty.
More on pipes later. I'm off work this week with the kids away - up to my eyes trying to demolish and rebuild the kitchen before they get back
I'll drop you a PM a bit later as well.

Ian
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