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Author Topic: Omra Makara D Class  (Read 180211 times)

omra85

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Re: Omra Makara D Class
« Reply #550 on: March 23, 2008, 03:04:40 pm »

Hi Bill
Marts right, it's one of those things that you just pick up from somewhere, but forget that not everyone knows it!
You can also use a tight(ish) fitting 'O' ring.  It goes on the bit of the flexi inner between the collet and the start of the outer tube. Then, if the flexi comes loose and slides back, it is stopped from going all the way by the O ring/silicon tube.
Sorry it's a bit late!
Danny
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martno1fan

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Re: Omra Makara D Class
« Reply #551 on: March 23, 2008, 03:17:14 pm »

Yes it is as Danny says put between flex tube and collet ,it was sometihing i was told from day one and it stuck.Plenty of things didnt stick mind but there you go im glad it helped you,pitty it was too late for Simon .You would be surprised how many experienced boaters have forgotten to use a shaft saver and lost expensive modded props they spent a fortune on  ::) but it wouldnt be fare to name them  {-).
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Blagmeister

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Re: Omra Makara D Class
« Reply #552 on: March 25, 2008, 05:33:49 pm »

 ;D

OK, I am a very happy bunny now!

After an abortive Easter weekend where I couldn't get any testing in at all, I finally got a chance to try out the new trim-tabs today, and managed to run a bit more fuel through the engine.

What a difference!!!

I can now give it the full beans down the straight at Kingsbury without any noticeable porpoising or chine-walking and the hull is running much dryer at 3/4 throttle and above too.  It is handling a bit more consistently too albeit, as it is going much faster than before, it seems a bit more edgy although I did increase the rudder throw a bit too, which might account for that. Even though I didn't spin out in any of the turns today, [mostly because I was backing off for the corners - not like me at all!], it might need a turn fin but I will try reducing the rudder throw a bit first. [Andy Rennie seemed to think that a fin might be in order but if I can get away with it then I will]. The plug colour is smack on and throttle response just great. Starts easily, runs at tickover speed nicely, pulls out of the hole quickly and goes like a *******!!!

Oh, incidentally, the cooling louvres on the engine covers seem to be working beautifully: the inlet air side were all nice and cool and the outlet air side were quite warm which suggests a good transfer of air taking place in the hull. The only downside might be as Simon suggested that it gets a bit wet inside during racing but as I plan to try out that Bernoulli-induced drainage method, it shouldn't really matter. Danny did you try that method yet? If I recall you were going to.

My water-cooling pipes need swapping around a bit as I have them feeding the manifold first, but the concensus seems to run to the head first, which I will deal with tonight during the post-test stripdown.

Overall though, now really looking forward to Torquay. All I gotta do is find a bigger bag tank - 500ml only lasted about 25 mins at full chat!  Any suggestions gratefully received!

 O0

Cheers!

Phil
"Who's a happy bunny now then?"  ;D ;D ;D ;D ;D
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Bill D203

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Re: Omra Makara D Class
« Reply #553 on: March 25, 2008, 06:41:28 pm »

Well done Phil
I use a 1.5 litre tanks. I get bored before it runs out. I think its around 40/50 Min's running time. as I said I get bored 1st. The tank came from Hobby Store. Simon put me on to it and so far it has been very good.
Have a great time in Torquay. Can't stand riding in boats of any size so will not be there. I will however be going to Bristol. If you are comming to Stevenage Please Book in ASAP.
Any one Else out there who wants to come Stevenage on the 4th May PLEASE BOOK IN ASAP. See the OMRA site for details. If you like me cant get in, Nor can I. Send me a mail on this site and I will book you in.Bill
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martno1fan

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Re: Omra Makara D Class
« Reply #554 on: March 25, 2008, 09:59:09 pm »

Glad to hear you now have her running well any video?,two words though TURN FINS all monos need them to turn well my stepped vee will spin out easy at full chat if im not carefull reason is because i havent fitted any yet  ::) have some been made by a mate on a  cnc machine along with a few other goodies for my new build see new thread about to be posted ;D.
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Blagmeister

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Re: Omra Makara D Class
« Reply #555 on: March 27, 2008, 05:17:22 pm »

Another productive day today.

I took the bull by the horns after re-routing the cooling pipes yesterday and opening out the water jacket nipples so they are the same bore right the way through.

I have been contemplating how to get an effective self-draining system for a little while and have finally grasped the nettle and drilled yet another hole in my boat!  I had a good wander around the net regarding the Bernoulli-induced drain system and have had a pop at it.

I drilled a hole in the transom at 30 degrees adjacent to the trim tabs where there should be an even flow of water at pretty much any speed and then inserted a length of annealed [interior end only] brass pipe through the hole and glassed it in. I'll stick a loop of hose on this into the bilges and silicon it in place. Testing tomorrow to see how it goes!  Also made up a turn fin and bracket and fitted that too. It's adjustable for angle and will kick up if I clobber anything.  Hopefully it will mean that I can keep my thumb in it on the turns now!

I also beefed up the layup on the port quarter as it was very thin and was flexing enough to have cracked the paint and lacquer. Bilge paint to go over the top of that in due course.

More testing and tweaking tomorrow plus a drainage test.

Cheers

Phil
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martno1fan

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Re: Omra Makara D Class
« Reply #556 on: March 27, 2008, 06:32:55 pm »

Interesting personally id have done a flush fitting in the bottom of the hull instead,never seen it done that way before hope it works for you.Check this thread out on how to do it ,this thread is by Glenn who also frequents this forum  ;).
http://www.rcuniverse.com/forum/m_7215771/tm.htm
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Blagmeister

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Re: Omra Makara D Class
« Reply #557 on: March 28, 2008, 06:08:47 pm »

I went by this article Mart

http://forums.radiocontrolzone.com/showthread.php?t=223704&highlight=Miss+Dumas

In it you can see a number of designs of drains but they all use the same fundamental principle.  Proof of the pudding being in the eating I went testing again this afternoon and tried it and the turn fin out.

Both work well.

The turn fin means I can now navigate the Kingsbury bouys at full chat without lifting off or spinning out. In fact I tried to spin it today and couldn't what it will be like when the water is more lumpy is another thing however.

The water drain works too. Not ridiculously fast as some people claim it can be but it works. I chucked a litre of water into the bilges and then threw the boat in and ran it round for a while. Brought it back in and there was just a dribble in the bottom. No more than I would expect. The conclusion is that it must therefore be going somewhere and that must be out of the drain!

Thats testing over for me before the Chase Race. Just one final tweak to make and that is to file a flat on my shaft where the drvie dog set screw bites as it keeps coming undone and I lose drive.  I'll thread locker it in place too. Other than that its all ready for Torquay!

Cheers
Phil
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omra85

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Re: Omra Makara D Class
« Reply #558 on: March 28, 2008, 11:12:02 pm »

Glad everythings gone Ok Phil (and thanks for the webpage advice).
I've put my bailer lower down - on the hull, but as your's is working, who knows, maybe time for a rethink! Drag -v- function!
I've still to test my 'C', so it will have to be between the downpours tomorrow. Course with yeeeaars of experience - should be just a matter of a half a turn on the mixture and off we go .........  as if!!!!
Couple of tips for the chase event -
Startup on the harbour, warm engine up, stop, clamp fuel and wait. Fit prop that will drive boat but allow PERFECT thottling.
Carry minimum equipment into chase boat (possibly spare tranny ???).
On the water - keep going (a chase boat takes TIME to stop, turn round and pick up your boat - don't waste this time).
20 mph constantly for 8 miles is better than 40 mph for 20 seconds, then 2 minute 'break', then 40 mph for 20 seconds!!!
If you're not used to travelling fast in small boats, be prepared for the rush of wind and spray, the  watering eyes, the cap blowing off the back of the boat - and all the while 'controlling' the maniac model which wants to disappear over the horizon.
Remember, the course is 4 miles in a straight line - don't spend all your time adjusting a couple of degrees on the rudder - let it run!
Lets have FUN.
Danny

 
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Bill D203

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Re: Omra Makara D Class
« Reply #559 on: March 29, 2008, 08:58:13 am »

Hi Danny
Sounds like my idear of Hell :( Boats are not for me. Have a great day.
Bill.
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martno1fan

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Re: Omra Makara D Class
« Reply #560 on: March 29, 2008, 11:30:43 am »

Hey Phil im glad it works for you my thinking behind the flush ones is they dont cause any drag which will slow you down more than you think.Good luck with her first race as Danny says its not all about speed its the finnishing that counts but hey what do i know i dont race   {-).
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Blagmeister

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Re: Omra Makara D Class
« Reply #561 on: March 29, 2008, 06:35:32 pm »

Hi Mart

it does work but I think I could have done with a larger bore pipe as the speed at which it empties is not that fast. Having said that, as it's only in the water flow by a mm or so, I don't think it's slowing me down that much. To be honest, I am going for reliability this season and if it proves competitive doing that then I'll stick with it as is. If not then maybe I'llmuck about with it but first lets give it a race!

Danny,

I am really looking forward to the Chase Race and full size boats are very much my thing. In fact in Milford Haven where I sail regularly, and used to keep my own boat, I even used to help run a water taxi service during the holidays, ferrying the grockles across the Haven in big 25' RIBs!

Thanks also for the advice about running the boat. I was planning on warming it up on the hard before jumping into the big boat but good point about clamping off - I hadn't thought of that. I plan to be a bit circumspect as this will be the first time the boat will have been used in anger other than testing so it will be a baptism of fire for it! Lets hope it's not too lumpy and the weather holds fine. The forecast is good by the looks of it.... 

How did testing with your C go today? I take it you got over to Kingsbury or wherever between the showers?

Cheers

Phil
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bigtee

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Re: Omra Makara D Class
« Reply #562 on: March 29, 2008, 08:06:27 pm »

phil sounds like you are ready  :D :D :D :D :D

one question , why do you want to clamp it off ?

tony
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Blagmeister

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Re: Omra Makara D Class
« Reply #563 on: March 29, 2008, 11:11:21 pm »

Well Tony hopefully clamping it off it won't make my eyes water too much! :P

I was merely going by Danny's sage advice. Presumably clamping it off ensures the fuel pressure in the carb stays constant and ready to go at a swift pull of the starter cord rather than having to pull fuel back into the carb but I dunno! I am just bowing to the advice of those with more experience of these things than me!  As long as I have a bit of fun and manage to keep my bum relatively dry, I'll be happy!

See you a week tomorrow Tony!! :D

Cheers

Phil
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Bill D203

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Re: Omra Makara D Class
« Reply #564 on: March 30, 2008, 07:31:22 pm »

Here I go Agian :( :(
Been out today and the tail end of the Ex pipe has now broke off :( :( :(
What do I do to fix this prob???? I have, and would like to use a MHZ pipe but I am very worried its going to pull the head apart??
ANY IDEARS WELCOME
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martno1fan

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Re: Omra Makara D Class
« Reply #565 on: March 31, 2008, 10:17:16 am »

Wow thats a looong header what tuned length do you have from flange to wides part of your pipe?,where is the break i dont see it ?.
Mart
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Bill D203

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Re: Omra Makara D Class
« Reply #566 on: March 31, 2008, 11:26:55 am »

Hi Mart
The break was at the tail end of the tuned pipe where it comes out the back of the boat.  I am now thinking that I will have to bite the bullet and get a complete new set up from Bluefishy. I am peed  of with it now as I have run out of ideas what to do next. I have spoken to Tony this morn and he is going to have a look though his old stuff to see if has any thing to fit the bill.
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2772e

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Re: Omra Makara D Class
« Reply #567 on: March 31, 2008, 11:39:20 am »

Bill,

You could always get one like mine. Have had no problems at all with the exhaust, the only bit i havn't.

Phil is also running one?

BW

Simon
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Bill D203

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Re: Omra Makara D Class
« Reply #568 on: March 31, 2008, 11:44:42 am »

Morning Simon.
Lets see what Tony comes up with. How much was yours?
Not working?
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Bill D203

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Re: Omra Makara D Class
« Reply #569 on: March 31, 2008, 12:45:24 pm »

Here you go Mart
1 broken tail pipe pic
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martno1fan

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Re: Omra Makara D Class
« Reply #570 on: March 31, 2008, 02:50:41 pm »

never seen one break there before how is yours held maybe you need more flexability to stop any undue stress due to vibration?,you never saifd how long you had the tuned length set at?.Your header looks way long that why i ask,id say its no way near its optimum length unless the picture is decieving?.you can get some decent pipes on the net for a good price but you will have to wait a week  ::).if you can wait that long and you cant get one  local try these places

http://www.bonzisports.com/exhaust.html

http://www.bhhanson.com/hbprod6.htm

 a mate in states recently got this said it was good
http://cgi.ebay.co.uk/stainless-steel-water-cool-tune-pipe-full-kit-rc-boat_W0QQitemZ290210026496QQihZ019QQcategoryZ34058QQcmdZViewItemQQ_trksidZp1742.m153.l1262
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Blagmeister

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Re: Omra Makara D Class
« Reply #571 on: March 31, 2008, 05:21:40 pm »

Thats bad news Bill. :(

Simon is right. I am also running one of Andy Payne's designed pipes and I have to say its beautifully made.  Nice and quiet and seems to produce plenty of oomph. Together with the integral header and water-cooled manifold it was around £145.  I know it's not the cheapest out there, but then you get what you pay for I guess.... Seems like money well spent to me.

Incidentally, I have just acquired some 2litre bag tanks and I will be testing one out this coming weekend. They are brand new re-usable urostomy bags [nice!] and seem to be completely petrol proof and so does the integral 90cm big bore pipe that comes with them. They are 2-port with a shut-off valve at one end. Not sure about using the valve as it may get knocked shut when racing with the associated lack of go that would come with that eventuality!  I am sceptical if they are going to be robust enough and hopefully I have some IV bags on the way too so it will be the pick of the bunch that wins out.  If I have any left over and anyone is interested, then let me know when you see me next weekend.

Hope you get something sorted out Bill.

Cheers

Phil
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bigtee

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Re: Omra Makara D Class
« Reply #572 on: March 31, 2008, 08:10:34 pm »

bill have a look in the parts bin but i dont have a spare complete set up , plenty of bits  :( :( :(

i would go for either a sikk 2 " band from barry or go for the  ebay pipe that mart has put up , i have one of these for the cat and for the money they are very good , or go for one of andys as he will make it for you if you need some thing a little differant  8) 8)

can you book me in for the race please

D20 , 2.4 gig,, pace/ zenoah

many thanks tony  O0
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Bill D203

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Re: Omra Makara D Class
« Reply #573 on: March 31, 2008, 08:36:47 pm »

Thanks for looking Tony. Have booked you in for the 4th May.
Been in contact with Tony Stoddard and he has come up with the bits useing as he dose my MHZ pipe. I have fitted a big pipe clamp round the Ex pipe which now means no weight at all on the header pipe or tail end. I am going to get a new manifold. shepherd hook S/S pipe, and a w/cooled cuppling. Fingers crossed. Bristol is but 2 weeks on Sunday.  :-\ :-\
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omra85

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Re: Omra Makara D Class
« Reply #574 on: March 31, 2008, 08:40:56 pm »

Sorry to hear about your pipe, again, Bill.
I think it's a vibration problem, rather than a materials issue.  The pipes are quite a size and even with the smallest 21 size, I've always used some bracket to support the main section of the pipe, not just the front and back.  It's preferable to have a rubber mount especiaslly with noisier engines.  The header, if bolted solidly at the engine, needs to be a loose fit into the pipe to allow vibration to dissipate at the joint rather than be transmitted to the pipe. The stinger can either be connected to the transom outlet by a flexiible pipe or, if space is tight, the end of the pipe can go through the transom but is supported by silicone tube between the pipe and the transom (tight hole).
I've been lazy this time and just made a straight support bracket, but it quitens down when the boat is in the water.
The pics might help show the idea.

BTW Phil, I forgot that your carbs are higher than our rear induction nitro ones so you don't really need a clamp! Although your reasoning for having one (preventing back syphoning) sounds so good that I will 'steal' your theory and pretend that is what I meant all along (- you're never to old to learn ...).

Bring the "Quells" on Sunday  {-) :D

Danny


Edit - spent so long typing it - you've got the answer yourself O0
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