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CEF speed contest Design Discussions

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Mad Re: CEF speed contest Design Discussions

Post  navion34 on Sat Jan 25, 2014 1:56 pm

Of course, The famous CAUDRON,
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Mad Re: CEF speed contest Design Discussions

Post  roddie on Sat Jan 25, 2014 3:44 pm

OVERLORD wrote:Good work Roddie, very precise and clean.

I am struggling making a cowl at the moment. It should end up with something like this:

CEF speed contest Design Discussions - Page 20 Caudro12

Thanks for the compliments.. and Please excuse this suggestion Lieven... but I always try to envision a way to make pseudo-parts for my models by using things you might find around the house.. and I thought of one for your cowling... Cleaning products come in containers that are already chemical resistant.. and many are "oval" shaped as well. What came to my mind was an "under-the-rim" toilet cleaner bottle...  Reading ...  Laughing really!!... Look at it's profile... I think you could make that work... cut a slot for the glow-plug clip.. and a hole for the needle-valve... and you have your totally enclosed Caudron engine cowling! Close enough for "stand-off-scale"!

CEF speed contest Design Discussions - Page 20 Toilet10

If your fuse is already built.. you will need to "fair-in" to the cowling.. and find the correct size bottle. My F8F-2's cowling is made from the cap from an automatic-air freshener cartridge...

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Mad Re: CEF speed contest Design Discussions

Post  OVERLORD on Sat Jan 25, 2014 4:34 pm

The idea crossed my mind Roddie. For weeks, each time I'm in the shower, I look at the bottom of the Head & Shoulders shampoo bottle.
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Mad Re: CEF speed contest Design Discussions

Post  roddie on Sat Jan 25, 2014 4:54 pm

OVERLORD wrote:The idea crossed my mind Roddie. For weeks, each time I'm in the shower, I look at the bottom of the Head & Shoulders shampoo bottle.

Here's a "Prestone" de-icer trigger-spray bottle for comparison with an engine...

CEF speed contest Design Discussions - Page 20 Presto10
CEF speed contest Design Discussions - Page 20 Presto11

EDIT 1: You could possibly set the engine back 2-3 inches and run an extended shaft in a 1/8" RC car bearing in the nose. (I've always wanted to try that with a P39 Airacobra model.) It would really help with balance on the Caudron.. but you'd have to check the contest rules for model "length".. and where it's measured from.

Edit 2: Here are the bearings you could use. A 1/8" dia. rod of "x" length.. threaded 5-40 on each end, would give you an extended prop-shaft to run in the nose-bearing. You could mount your engine back near the wing.
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Mad Re: CEF speed contest Design Discussions

Post  roddie on Sat Jan 25, 2014 8:24 pm

I wasn't satisfied with my 1/32" ply cowling supports, so I cut them back and installed .005" Brass tabs. I wrestled with this method in my mind a bit...  Huh...  before hacking away... The new Brass tabs do work well, and support the inner-rear flange of the cowl with a "spring-like" force. The cowling lines-up real nice. It is secured to the nose with #2 wood screws, to the top and bottom fuse rails.. which are 1/4" sq. Spruce.

the 1/32" ply supports... shown; before cutting back

CEF speed contest Design Discussions - Page 20 1-24-122


the replacement Brass support tabs in place

CEF speed contest Design Discussions - Page 20 1-25-112

Brass tabs "spring-lock" against inner cowl flange.
CEF speed contest Design Discussions - Page 20 1-25-113

I need to finish drilling top/bottom cowl mounts, and locate hole position for the needle on the inboard side. Then I will be able to start with finishing. I think...
CEF speed contest Design Discussions - Page 20 1-25-114

Thanks all.. for the nice comments. I am enjoying building this model.
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Mad Re: CEF speed contest Design Discussions

Post  OVERLORD on Sun Jan 26, 2014 4:35 am

Thanks Roddie for checking that out.

During the last 2 weeks I made a jig for forming balsa sheets to the desired shape:

CEF speed contest Design Discussions - Page 20 Imgp7214

a piece of plywood at rear end of the cowl and 1 fwd where the noseblock will be and a 3rd one in way of the firewall where the cowl changes shape. All fixed to a screw and positioned at the required distances.

CEF speed contest Design Discussions - Page 20 Imgp7215

I soaked 2mm sheets in water for at least 1 hour and pinned it around the former, then let dry on the radiator. I first wrapped cling film around the plywood so it won't soak any water from the sheeting.

CEF speed contest Design Discussions - Page 20 Imgp7216

I then glued both right and left pieces together.

CEF speed contest Design Discussions - Page 20 Imgp7217

CEF speed contest Design Discussions - Page 20 Imgp7218

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Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Sun Jan 26, 2014 7:05 am

Beautiful work Lieven.

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Mad Re: CEF speed contest Design Discussions

Post  ebeneezer on Tue Jan 28, 2014 11:20 am

Wow, thats some really good work. now filed into my memory banks. If we do this again next year, I will choose something with a cowl to hide the engine. Especialy now I've seen how to make a good cowl. Now I'm thinking a Gee Bee R3. By the way, the reason I'm posting is I now have my Nitro and APC 4.75x4 prop, thanks Ebay. My newly assembled speed engine had  better look out !!!. 
 Very Happy Flying
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Mad Re: CEF speed contest Design Discussions

Post  getback on Tue Jan 28, 2014 4:55 pm

Very impressive work Roddie and Lieven I have been keeping up with this building thread and am inspired by the wonderful , hard , work that is going into this project that pays with only pride! some have forgotten about that  Friends/Meeting  damn I sound like SD now ....only funning of coarse it takes us all to make a difference . nice to get to learn some tricks and have a good time too.
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Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Tue Jan 28, 2014 6:27 pm

So here's one for the mathematicians in the crowd. How much of my 18% fuel do I mix with 16oz of 35% to get 30%????

The scratching my head Jim.
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Mad Re: CEF speed contest Design Discussions

Post  roddie on Tue Jan 28, 2014 10:44 pm

JPvelo wrote:So here's one for the mathematicians in the crowd. How much of my 18% fuel do I mix with 16oz of 35% to get 30%????

The scratching my head Jim.

Well Jim................. 1st of all.. that's a LOT of fuel... Do you really need 16oz of 30%?? (maybe.. if you're doing some hard-core test-runs...) If a 1:1... 25/35% gives you 30%... (correct?) then I would think a .75:1... 18/35 would yield close to 30%...? There's a thread on this somewhere, with a formula for calculating exactly.. but I don't think I'm too far off. (I'm willing to bet that "stated" nitro content can vary up/down within a percent or two with "any" fuel blend...) "Damn it Jim"... (to quote "Bones"...Deforest Kelley-Star Trek) Now I'm scratching "my" head!!  Huh... 

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Mad Re: CEF speed contest Design Discussions

Post  OVERLORD on Wed Jan 29, 2014 2:22 am

Jim,

I do not know the exact formula to get there but I did some triel and error and came very close.

I started with 1 liter of each:

1L or 100 cl of 35% = 65 cl fuel and 35 cl nitro
1L or 100 cl of 18% = 82 cl fuel and 18 cl nitro

To make it short, when you add 42% of your 1 liter quantity of 18% fuel, you end up with a quantity of fuel with 30% nitro:

65 cl + (82 cl x 0,42) = 99,44 cl
35 cl + (18 cl x 0,42) = 42,56 cl

this makes a total of 142 cl = 1,42 l

When deviding this gives:

99,44 / 1,42 = 70,02% fuel
42,56 / 1,42 = 29,97% nitro

So you need to add 42% of 16 oz of your 18% fuel to end up with 30% fuel

Hope this helps.

Lieven
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Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Wed Jan 29, 2014 6:48 am

Thank you both Lieven and Roddie. I will mix some fuel and get some runs in this weekend!

Jim
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Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Thu Jan 30, 2014 6:22 am

CEF speed contest Design Discussions - Page 20 JY7S3dp
CEF speed contest Design Discussions - Page 20 86oHeoE
CEF speed contest Design Discussions - Page 20 AV2T37W
Should have them in the air Saturday.
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Mad Re: CEF speed contest Design Discussions

Post  getback on Thu Jan 30, 2014 6:39 am

Looking good there Jim , you build racers ? Is that  a back up plan or just a lot of spare time, Good luck on the trial runs! I have been having some issues with weather to go w/ or w/out a on board tank, and that's holding up the engine mount I am going to do something today so I can get my CG right  Cool
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Mad Re: CEF speed contest Design Discussions

Post  roddie on Thu Jan 30, 2014 9:21 am

Congratulations Jim! Both models look AWESOME!! The side profile photo looks like it won the contest already!!! BEAUTIFUL!

Best of luck on Saturday! I hope the weather cooperates for your test flights.

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Mad Re: CEF speed contest Design Discussions

Post  duke.johnson on Thu Jan 30, 2014 9:31 am

Really nice work Jim! I need to get going again, the contest deadline is coming up fast.
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Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Thu Jan 30, 2014 10:09 am

Thanks guys,

People in other parts of the country won't like this but if the temps stay below 80 on Saturday it should be fine.

Jim
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Mad Re: CEF speed contest Design Discussions

Post  navion34 on Thu Jan 30, 2014 11:48 am

Very good job. Congratulations !!!
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Mad Re: CEF speed contest Design Discussions

Post  Cribbs74 on Thu Jan 30, 2014 12:05 pm

Excellent work Jim. Very impressive.
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Mad Re: CEF speed contest Design Discussions

Post  crankbndr on Thu Jan 30, 2014 12:44 pm

Nice work, what ya got for power? I did the fuel problem and came up with add 7 oz 18% to bring the 35% down to 29.8%.
I might have got lost in the black hole of math.
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Mad Re: CEF speed contest Design Discussions

Post  OVERLORD on Thu Jan 30, 2014 2:48 pm

good looking planes, Jim, will you make a video on saturday?
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Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Thu Jan 30, 2014 7:15 pm

crankbndr wrote:Nice work, what ya got for power? I did the fuel problem and came up with add 7 oz 18% to bring the 35% down to 29.8%.
I might have got lost in the black hole of math.
Both engines are black widow cylinders with killer bee cranks. The back plates are bored as big as you can go and still have a Reed seat and enough meat to hold the spray bar. Fine thread needle valves so I can run bladders , Mylar reeds. The Mustsng has an old glo-bee head and the corsair has a galbreath/Nelson plug combo. Performance is identicle between the heads, about a 1500 rpm gain if memory serves. Last time I ran the Mustang engine it held 22k with 18% and an APC 4.75x4. The corsair is 500-700 rpm behind it. I will bench run with 30% tomorrow, if I can figure out how to brew 30% lol! 

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Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Thu Jan 30, 2014 7:17 pm

OVERLORD wrote:good looking planes, Jim,  will you make a video on saturday?
I will video Saturday but I won't post them, I don't want to "show my hand" just yet. It is a competition after all!

Jim
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Mad Re: CEF speed contest Design Discussions

Post  roddie on Thu Jan 30, 2014 8:39 pm

JPvelo wrote:
OVERLORD wrote:good looking planes, Jim,  will you make a video on saturday?
I will video Saturday but I won't post them, I don't want to "show my hand" just yet. It is a competition after all!

Jim

Will you be test flying on Saturday with your Son? Has he flown his "Mouse Racer yet? I hope all goes well... I know you are concerned about "nose-overs" when landing. Do you plan to "hand-launch" over a soft grassy flying area; just to log preliminary lap-times? You could save the "paved-circle" for the official flight.

My test-flights will be un-assisted "stooge" launches (as usual)... and I plan to scout-out an area where a R.O.G. is possible... with some kind of adjacent "soft" (forgiving) surface is present... maybe along the perimeter of a parking lot with no curbing. I might just find a grass field... and  make-up 15-20 feet of cardboard "radius" runway segments to launch from, for my first tests.

It's been consistently below freezing here in New England for the last week or so... and it could "stay that way"... well into March. It's just as well... because my airplane entry isn't even painted yet... I'm EXTREMELY envious of your weather there in AZ!!!!!!!

All the Best!

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