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Capricorn - the ultimate flying boat.

Old 11-11-2015, 10:29 PM
  #2826  
Larry3215
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By the way, I used EPS/styrofoam for the floats on my mini Cap. They have another advantage in that they are lighter than the other foams. The only downside is they are also more fragile than the blue/pink foams. Ive broken those floats more times over the years than I ever did with the other foams. With all the glue Ive used to put them back together they probably are not really any lighter at this point.

EPO might be a good alternative to try.

As always, every choice you make in model design is a trade-off of some type
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Old 11-11-2015, 11:19 PM
  #2827  
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EPS (good old Styrofoam) comes in an assortment of weights. I've seen from 1 lb/ cubic ft to 4 lb/ cubic ft.

Considering that EPO is expanded in a similar manner to EPS, It probably also can be made in assorted densities. I've only seen it expanded into molded shapes, not the 4 ft X 4ft X 12 ft blocks you can get with EPS. (which get cut into the assorted sheet and block sizes)
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Old 11-12-2015, 10:46 PM
  #2828  
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I cut the floats for my (late) Capricorn out of foam packing supplied with my new TV.It was a closed cell type foam,but a bit flexible.It was only 25mm thick,so I used Gorilla glue to glue two pieces together.The bottom was covered with FG reinforced tape.No discernable wear,and no water ingress that i could detect.
Unfortunately,I don't know exactly what type of foam it was.I thought some sort op polypropylene.I do know it didn't take coloring with felt pen very well.
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Old 11-12-2015, 11:13 PM
  #2829  
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I have seen some molded packing that was EPO, though EPP is more common.
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Old 01-12-2016, 01:19 PM
  #2830  
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Default A bit of advice

Hi Larry

Just wondered if you wouldn’t mind answering a few questions that have come to mind before I get into building my Cap.

I have previously built an Aquarius which was a bit smaller than your Mini-Cap (which was over Year ago now).

I followed Leadfeathers Aquarius design ‘cos I was a raw noob and had not at that time, discovered the Cap (thread).

Is there an aerodynamic reason why the panels are joined in a Vee and not with the Flat bottom between panels like on the Aquarius ?

Most of the Caps have the motor on a pylon or pod out the front is this necessary for balance?


Would the equivalent of a Blue Wonder (Hobbyking or Turnigy 2730-1700) be sufficient for a Cap of size of the 85% version be OK for about 100W of power ? My type of flying would be stooging around rather than racing around. I see that my system would be similar to what DHC Beaver has indicated on the previous page.

I'll probably build mine out of Depron this time

A great thread very informative.
Geoff
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Old 01-12-2016, 05:41 PM
  #2831  
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Hi Geoff,

There isnt any real difference between the Aquarius and the Capricorn aerodynamically. I personally prefer the V joints because they are simpler and faster for me to do. Plus I dont use any carbon cross braces. Done correctly, I think the V joints are a bit stronger, but the differences are really pretty minor.

Leadfeather on the other hand prefers the flats for the following reasons:

The flats were added for the following reasons:

1) No gaps in the elevons required at the back. Better wing efficiency??
2) Easier to mount the sponsons
3) Easy to hook up the carbon cross braces to the bottom of the side flats.
4) Easy to build, no angle cutting required.
5) The center flat provides a convenient place to mount all of the guts. The battery is going on the bottom, all else on top.
Id say pick the one you think will work better for you as far as what you think looks best and will be easiest for you to build.

The one major difference between the Cap and Aquarius is the VT yaw. Ive tried the VT yaw thing several times and I dont like it at all - UNLESS - you also have a functional rudder.

The one thing I really hate about VT - with no rudder - is that you cannot steer the model when the throttle is off. Imagine comming in a little hot so you shut down the throttle. Then you realize you are about to crash into something, but now you cant steer unless you power back up - right into what ever you were about to crash into!

For me, a large rudder works better over all. Mostly because it lets you control the modle with the power off, but also because it saves weight and is faster/simpler to build. VT is cool though

If you want your Capricorn/Aquarius to fly slooooooowly and float like a feather, the single most important thing is weight.

Keep it light. Use little or no paint or covering. Use a small motor and small battery and small servos and dont beef it up unnecessarily.

As far as the motor being out front - thats mainly for balance reasons. How far our front it needs to go will depend on the motor and battery you use and where you put the servos, how heavy you build etc etc. I prefer my Caps with the CG further back than almost everyone else - but Im a bit odd

Your motor should work fine. Weight wise it is an excellent choice (will certainly need the extended nose for balance) as long as it can safely hit 100 watts for short bursts. I prefer motors with a lower kV - 900 to 1200 or so - so I can spin a larger prop. You get better thrust and acceleration with a larger prop, but I think you will be ok.

Good luck and keep us posted on how it goes!
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Old 01-17-2016, 01:02 PM
  #2832  
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Larry

Thanks a lot for all the information, I was thinking along most of those lines.

I will try to keep it light. When I built my Aquarius, I only used two different colour packing tapes in stripes top & bottom.

I actually have started to refurbish it, it seemed a shame not to give it one last 'phoenix' chance. The main wing is generally OK, servos and pushrods work fine and elevons Ok. Most of the damage was in the nose/motor mount area and sponsons, so I will try and "macgyver" a new way of mounting the new more powerful motor, where the old ones (twice) broke off. We all know that 'mods' always add more weight.
This refurbishment of course may not work 'cos my flying skills are still only noob.

I attach a pic of my bird. The sponsons and front end are now different.

Geoff
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Old 01-17-2016, 03:54 PM
  #2833  
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The rudder is a little small.... ...but at least it has one! I like it

Good luck!
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Old 01-22-2016, 08:06 PM
  #2834  
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Hi Larry : I am not only a newcomer here, but I am also new to electric's. I want to build your standard size, this one Capricorn y08m07d27.pdf

I have in my possession an Emax BL 2210/30 motor that I run on 3 cells using a 1500 LiPo pack. Would this motor be enough to power this Capricorn ?

Thank you.

Eddy
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Old 01-22-2016, 09:08 PM
  #2835  
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Hi Eddy,

That motor wont be ideal - the kV is on the hi side so you probably wont be able to spin more than a 7" prop on 3S packs.

That means relatively low thrust and higher pitch speed for the power its putting out. That means slower acceleration at low speeds and a little more effort/power needed to take off and climb etc.

It should still fly ok though. Lots of other guys have been flying Caps with similar motors.
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Old 01-22-2016, 11:00 PM
  #2836  
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Originally Posted by Larry3215 View Post
Hi Eddy,

That motor wont be ideal - the kV is on the hi side so you probably wont be able to spin more than a 7" prop on 3S packs.

That means relatively low thrust and higher pitch speed for the power its putting out. That means slower acceleration at low speeds and a little more effort/power needed to take off and climb etc.

It should still fly ok though. Lots of other guys have been flying Caps with similar motors.
Thanks Larry; I also have available to me a Turnigy SK 2830-750, which weighs considerably more at 59g. I think that this might be overly heavy, what do you think ? Of the two motors mentioned, which one would be more suitable ?


Eddy
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Old 01-22-2016, 11:12 PM
  #2837  
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Id start with the lighter one first and see how it does.
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Old 01-23-2016, 01:02 AM
  #2838  
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Thanks Larry, I will try the smaller one first. What kind of wing area am I looking at for this one Capricorn y08m07d27.pdf . Is this what you consider your Standard size ? I want to compare your Capricorn area to the previous plane that I had that motor in.

Thanks again for all of your help with this, it's much appreciated.


Eddy
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Old 01-23-2016, 02:54 AM
  #2839  
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I forget the exact area but its in the ballpark of 1000 sq inches. Probably a LOT more wing area (and a LOT lighter wing loading ) than any plane you would have had that motor in
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Old 01-23-2016, 03:33 AM
  #2840  
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Originally Posted by Larry3215 View Post
I forget the exact area but its in the ballpark of 1000 sq inches. Probably a LOT more wing area (and a LOT lighter wing loading ) than any plane you would have had that motor in
Thank you Larry, you are to be commended for starting, and maintaining this wonderful thread. It must put quite a demand on your time.

Thank you Sir.

Eddy
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Old 01-28-2016, 03:42 AM
  #2841  
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I have started my "build" of the regular size Capricorn, Capricorn y08m07d27.pdf , using the paper covered foam board from the Dollar Tree store. It's what I had available in the shop, and for strength I will leave the paper on. Since I live in the desert, and fly from a paved runway only, I am equipping it with skids, and not sponsons or floats. No water flights are planned. I don't know if this type of foam has ever been used in the construction of a Capricorn, and I expect it to come out on the heavy side, especially since I am using 100% hot glue in construction.

My motor is capable of about 130 watts. From every one here experienced in flying this aircraft, what is the maximum weight that I can expect to fly using this type of foam board on this motor ? I expect to slow fly mostly, and no wild and crazy stuff is planned .

Thank you all.

Eddy

Last edited by Eddy; 01-28-2016 at 06:53 AM.
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Old 01-28-2016, 06:52 AM
  #2842  
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Eddy,I built my original capricorn from that board,and found it to be much too heavy.If you soak off the paper,it'll save more than half the weight,at the expense of some rigidity.
You could get some strength back in it with a 2 or2.5mm carbon fibre rod across the back,just in front of the fin.
I'm building an 85% now from such board without the paper,and although the foam is floppier,it,s so much lighter.
A light Capricorn just flies much better.
I think your one might struggle with the 2830 if you leave the paper on.
I used a 3236 to get enough power to fly it properly.Unfortunately,that also meant more weight again,and a larger battery pack,more weight
On my 85%,I'm going to use a DT750 bell motor.I'm not sure of the kv rating,as it came out of my broken HK autogyro.But it seems to be able to swing a larger prop than a can type motor.
Please don't think I'm trying to discourage you in any way,just putting in my 2 cents worth.
I'll add some pics of mine when I charge my camera batts.All the best.
Hans.

p.s. I use brown Gorilla glue on this type of foam.
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Old 01-29-2016, 06:26 AM
  #2843  
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Thank you Beav, I will be making some really big changes.
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Old 04-15-2016, 08:11 AM
  #2844  
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Guday everyone ,its been a long time since I posted but as with everything somtimes life gets in the way ! My local hobby shop has sadly closed and as I can't resist a bargain i ended up with 30 sheets of 2mm depron next thing I built a 50% of a 85 % Capricorn.
1804 2800kv turnigy motor, 12 amp esc, 5x3 prop auw 155g (with 850 mw 2cell ) got excited did a taxi test half throttle and it went straight up, too much up trim . half roll and some minor repairs to do. Larry may not approve . photos to follow hpoe all are fit and well
Johne
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Old 04-16-2016, 02:28 PM
  #2845  
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Test flew this morning ,a bit too much breeze but I had to give it a go, our strip has been suffering lately from rabbit attack and it took a few attempts for the little cap to climb out of the holes but it did and to everyones surprise flew perfectly, the wind hardly affected it .
I did not think a capricorn that small would work but I was wrong . once again Larry your design is special. Forgot the camera so photos still to come .
stay safe Johne
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Old 04-17-2016, 01:12 AM
  #2846  
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Sadly,my 85% is no more.On the first flight,it was extremely nose heavy,and after straggling through most of a circuit,it crashed.
I glued up the broken bits,and replaced the motor with a smaller one,allowing a smaller 3s 1500 battery.
Very slow flight was nice,but a windgust blew it up on it,s side,and I lost control.This time,the crunch was fatal.
I think I'll go back to a full size for my next one.
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Old 04-17-2016, 02:13 AM
  #2847  
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DHC, sorry to hear about the 85%, I have half a shed full of crashed planes I find it hard to scavenge them for parts let alone throw them out, but when there is a new one on the building board and I need something well there must be a sacrifice. The new mini is using electrics from the first mini quad I ever built ,so that took some nerve to disasemble.
Good luck with the next one.
Johne
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Old 04-17-2016, 10:58 AM
  #2848  
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some photos of the mini-cap, that is a 1 ft rule it is sitting on.
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Old 04-17-2016, 10:05 PM
  #2849  
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That,s a cute looking Capricorn,John.
What,s the twisted material you,ve used for the elev/aileron pushrods?
Tell the dogs to stop playing up to the camera
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Old 04-18-2016, 10:21 AM
  #2850  
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DHC. thanks , the twisted rod is just a fibreglass rod from hobbyking, I bought a dozen lengths years ago and it makes good pushrods as the twists make the heatshrink hold on well , they also make it very stiff. as for the dogs I did not even realise the were in the shot till you pointed them out , they love helping out with the builds so thought they deserved some credit.
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