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Capricorn - the ultimate flying boat.

Old 12-20-2007, 02:33 AM
  #151  
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Originally Posted by leadfeather View Post
These posts are all blanks on my computer too, no pics.
Same here, no pics. I understand that there is going to be new photo software here soon but my approach has been to resize pictures to 800 by 600 pixels and I use Google's Picasa to organize all my pictures. It is free and will export pictures for you at any size that you only have to setup once. I have had no problems at all since I started doing that...

RM
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Old 12-20-2007, 08:21 AM
  #152  
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Bob,

When you up-load pics are you using the first option at the top of the upload window?

Upload File from your Computer

Or are you using the second option 1/2 way down the page

Upload File from a URL

If your using the second option and putting in a link from a file on your computer, that could be the problem. The software cant find the file when your not on-line and maybe not when you are.

Try the first option at the top of the upload page - or just e-mail them to me and I'll give it a try.

I PM'ed you my e-mail addy.

Larry
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Old 12-20-2007, 08:26 AM
  #153  
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Originally Posted by RocketMan View Post
Thanks Larry, those last two messages are very valuable! I have been trying to figure out why my E-Starter behaves the way it does and now I realize it desperately needs some down thrust (it immediately goes near vertical on full throttle).

On my Cap I think I am going to be able to get the motor mounted quite close to the 'V' because I am planning to use a GWS stick mount. Perhaps I will start with no up thrust and then put shims between the motor and the mount if I need it.

RM
Dont forget - you need to have the CG fairly close first. A nose heavy condition can cause the same thing to happen.

Also, planes like the e-starter are designed with extra positive pitch stability. The net result is that as speed increases they will always climb unless you re-trim.

Do the test where you fly at hi speed - trim the elevator for hands off flight at full throttle so its not climbing or diveing.

THEN chop the throttle and see what it does. Thats a better indication in your case I think

Larry
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Old 12-20-2007, 08:40 AM
  #154  
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Try this trimming chart. Its designed for patern planes but is good for any flying machine.

It takes you thru thre entire routine

Larry
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Old 12-20-2007, 08:57 AM
  #155  
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Originally Posted by paulhealey View Post
hi folks!im currently flying a gemini,well still trying to get it set up properly!there is just no one in the uk that flies them.Anyway i do fly it and it flies ok,but why do i need lets say 5mm up elevator and 3mm up aileron trim,for straight and level flight?the instructions show neutral surfaces.i tried this but crashed.The c,g is as robbe recommends.
larry can you tell me what you mean by 'c,g being close to neural'?what does neutral mean?
Now where can i find some 6mm depron?
All flat plate wings (no airfoil) will require some UP trim to fly level. The exception to that is if the cg is way back. In that case it will fly with the wing UP without up trim. It will also be less stable.

I've never flown a Gemini, but your situation could be several things.

Have you tried the test I described above? Fly at full throttle, trim for level flight, then chop the throttle and see what happens. Your thrust line may be off. I seem to recall some people having that problem.

Next is CG (actually you should check CG first) - How does it fly inverted? Does it take a lot of "down" elevator stick to hold it level when its upside down? For most people, a little down is about right.

Thats what I mean by "neutral" CG. A perfectly "Neutral" CG location is where the plane will fly up-right AND inverted with no elevator stick changes. You fly along level hands off, then roll inverted and it still flys level hands off.

Keep in mind that when the CG is that far back many (if not most) planes will be far more dificult to fly. They will be on the edge of being unstable in pitch - or down rite nasty unstable in pitch in some cases.

The Capricorn is more forgiving of having the CG way back than many planes, but it still gets "pitchy" when the cg is further back. I happen to like it that way because it will do very tight loops and flips. Unless your used to flying a tail heavy 3D plane you might want to keep the CG a little more forward so you need some "down" stick to hold level when inverted.

The aleron trim you have is probably caused by the torque from the prop. Are you running a larger prop than they recomend?

The Gemini is a lot smaller span than the Capricorn and prop torque can have quite an effect requireing some opposite alieron trim to counter act it. It might also be agravated by having too much or to little right thrust on the motor stick.

This design has a lot of built in "dihedral" in the outer panels and any sideways crabbing flight will induce a rolling moment - again needing aileron trim to correct.

The Gemini is a lot smaller (about 1/4 the wing area) and flys faster so any trim, torque, CG or thrust errors are far more noticable in flight.

Try going thru the trim chart above, make any necessary changes, and see how it goes.

Larry
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Old 12-20-2007, 08:59 AM
  #156  
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For 6mm Depron in the UK, I dont know.

You should have it easier than we do - its made somewhere in Europe and we have to import it

Larry
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Old 12-20-2007, 09:04 AM
  #157  
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Originally Posted by paulhealey View Post
hi folks!im currently flying a gemini,well still trying to get it set up properly!there is just no one in the uk that flies them.Anyway i do fly it and it flies ok,but why do i need lets say 5mm up elevator and 3mm up aileron trim,for straight and level flight?the instructions show neutral surfaces.i tried this but crashed.The c,g is as robbe recommends.
larry can you tell me what you mean by 'c,g being close to neural'?what does neutral mean?
Now where can i find some 6mm depron?
I just took a closer look at the pic you posted. It looks like you spinning a fairly large prop. Thats probably the reason for the aileron trim you need.

Does it roll with throttle changes? One way when you throttle up and the opposite way when you power off?

The only fix is to A) live with it or B)get a motor with a higher Kv so you can spin a smaller prop or C) run higher cell count so you can spin a smaller prop with the same motor.

C will add more weight (possible CG problem) and you may not have room for a larger pack.

Larry
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Old 12-20-2007, 01:07 PM
  #158  
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Thanks for replying larry. so a flat 'wing' must have a small amount of up trim to fly?The trouble is my model on water or grass wants to lift off when it gets to a certain speed,it can catch you out.it would be nice to lift off, when I want to lift off and not when it decides to.i 'd like to control the model rather than it controlling me.im sure you know what i mean.
I flew inverted today with long passes and it does need a touch of down elevator,so i guess its at optimum c,g.
thanx for posting the trimming chart im gonna read it then get the gem out and run through the various thrustline tests.cheers
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Old 12-20-2007, 09:29 PM
  #159  
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"Trimming" a plane can be time consuming.

I rarely do the whole thing all the way to optimum for a model unless there is a bad habit Im trying to correct.

Im usually too interested in just flying to spend the time. Once I get it "close enoug" I stop.

It is worth doing to.

Part of the problem is that some models are more prone/sensitive to certain things than others. So its always different for every plane.

On top of that - every thing you change effects something else.

You can go thru the entire list and change one thing towards the end. Now you have to start over because THAT change effect the earlier settings.

The final thing is that your never going to get it all perfect in all aspects of flight.

Trim a plane for ideal 3D flight and it wont do so well in patern. Trim for hi speed and low speed suffers etc.

I think its fun playing with the different aspects of the theory and seeing how it works out. It makes working on new designs and solving "mystery problems" a lot easier, but its mostly just for the fun

Larry
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Old 12-21-2007, 01:04 AM
  #160  
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Default Maiden

I maidened my Capricron just before sun down today. It flew beautifully. I had to make a few minor adjustments to the pitch trim and that was it.

Rolls, high alpha, inverted, tight tight loops, rise off water from a large puddle it did it all...easily

A few things really impressed me. This thing will fly incredibly slow, probably slower than anything I've ever flown. It flies inverted very easily. I can do flat rudder turns in about a 6 foot circle. It is a nice combination of easy to fly yet very maneuverable.

Below is a picture of my build. I used 1/2" foam for the center section. I didn't raise the thrust line since there is ample prop clearance anyway.


It's big, it's kinda homely, but it flies really really nice. Two enthusiastic thumbs up. Thanks for a great design Larry!
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Old 12-21-2007, 01:17 AM
  #161  
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Originally Posted by leadfeather View Post
I maidened my Capricron just before sun down today. It flew beautifully. I had to make a few minor adjustments to the pitch trim and that was it.

Rolls, high alpha, inverted, tight tight loops, rise off water from a large puddle it did it all...easily

A few things really impressed me. This thing will fly incredibly slow, probably slower than anything I've ever flown. It flies inverted very easily. I can do flat rudder turns in about a 6 foot circle. It is a nice combination of easy to fly yet very maneuverable.

Below is a picture of my build. I used 1/2" foam for the center section. I didn't raise the thrust line since there is ample prop clearance anyway.


It's big, it's kinda homely, but it flies really really nice. Two enthusiastic thumbs up. Thanks for a great design Larry!
That looks great leadfeather! I am hoping to maiden mine on the weekend (in the snow and ice, not water) but Christmas activities seem to be getting in the way...

I'm curious where you ended up with your CG (how far back from the leading edge?) and where you placed your battery.

RM
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Old 12-21-2007, 01:50 AM
  #162  
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My CG is back about 9".

I stuck the battery on the bottom of the center strip with velcro.

Just behind the battery is an access hatch for the esc and Rx.

In my build, I didn't do any mitering of the wing joints. The fuse and fin was used to closed up the gap in the center joint. The sponsons and extensions closed up the gaps on the outer wing panel joints....saved a lot of work this way.
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Old 12-21-2007, 02:05 AM
  #163  
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Thanks for that. I have been trying to get the CG at 7" but I think it is impossible so I am glad that you were ok at 9" which is likely the best I can do. I can hardly wait to fly it!

RM
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Old 12-21-2007, 04:57 AM
  #164  
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Congrats Leadfeather!

That 1/2" blue foams looks like its working out very well.

What is your all up weight?

It looks like you didnt add any extra bracing/straping/carbon along the front edge of the wing. Do you think its going to hold up ok?

One thing you guys are doing differently - on mine the motor mount extended forward a few inches. By mounting the motor back flush your battery will have to mount more forward to get the same CG.

Good job!

Larry
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Old 12-21-2007, 05:11 AM
  #165  
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Originally Posted by RocketMan View Post
Thanks for that. I have been trying to get the CG at 7" but I think it is impossible so I am glad that you were ok at 9" which is likely the best I can do. I can hardly wait to fly it!

RM
Im at about 10" back on mine now - but thats on the edge of too tail heavy for most folks. It wants to climb when inverted just a tad.

The key when your first starting flying this model is go easy on the throttle. Like Leadfeather says - it flys super slow and likes it that way.

Most of the guys who have had "events" on the maiden were flying at full throttle from the get go. It can get very wild at full throttle and full speed.

I think that if you limited the power and throws this thing would make an excelent primary trainer. It is super stable if you take it easy, but can get wild when your ready

Larry
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Old 12-21-2007, 05:13 AM
  #166  
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Oh wait Leadfeather - dont tell me you broke the tradition?

No crash? No trees, fences, dogs, raindeer or fire hydrants? No "events" of any kind?

Good job!

Larry
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Old 12-21-2007, 05:33 AM
  #167  
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Originally Posted by boberos View Post
Thats weird, larry,

Post 131 a pic of approach to land.
Post 132 Banked turn
Post 135 just after T.O.
Post 136 Taxiing

The pics appear on my computer screen; quite large in fact. Am I the only person that can see them?

Bob
Bob sent me the pics of his Capricorn. The file names were odd, that may have been the problem.

It looks great!

Larry
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Old 12-21-2007, 12:20 PM
  #168  
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The 1/2 blue foam is good stuff. It is thick enough to sand the leading edges round. It is much stronger than the 1/4" foam. I think it wiillhold up fine, time will tell.

I put the motor the three inches forward, but I also brought the foam out to that point to make it look better (IMO). The cg I quoted, 9", would be from the leading edge location per the plans.

I'll weigh mine later and report back. It is not very heavy.

No trees, no crashes; I'm not sorry to break that tradition! It was a stellar maiden flight. Two flying buddies got to fly it too. It is so easy to fly they were doing aerobatics within several seconds of taking the stick.

Originally Posted by Larry3215 View Post
Congrats Leadfeather!

That 1/2" blue foams looks like its working out very well.

What is your all up weight?

It looks like you didnt add any extra bracing/straping/carbon along the front edge of the wing. Do you think its going to hold up ok?

One thing you guys are doing differently - on mine the motor mount extended forward a few inches. By mounting the motor back flush your battery will have to mount more forward to get the same CG.

Good job!

Larry
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Old 12-21-2007, 02:57 PM
  #169  
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Here are some details for my Caricorn as seen in the above pics.
The other mod was to add a bamboo skewer between the the floats to prevent fuselage cracking at the dihedral joint.

For the 85% Capricorn:

Control surface Deflections using elevons with a 2" chord.
Low rate 3/4" up & 3/4" down
High rate 1" up & 1" down

Mine flys fine with a 400XT & 3S1200 lipo but needs a 9X4 prop to get unstuck from the grass.
I just weighed mine; 18 oz ready to fly.

Changes for next one.
5 gm servos instead of current 20 gm ones. (Will probably switch servos when next batch arrives, for a saving of 45 gm or 1 1/2 oz.)
Attach floats 1 1/4" farther fwd. Remember I attached these ones assuming a 40%
C of G. Nice thing about foam is that I already cut 1" off rear of step so that it is now near my 28% C of G. Step should be very close to C of G.
I might build it about 5% smaller to reduce drag & increase speed. I don't expect much of a weight saving from using less foam.

All panels are 7" wide so you need a piece of FFF that is 28" wide & 23 1/2" long plus 6" on the other side of the fold.. The natural fold in the FFF serves as my L.E. & it folds 6" back from the L.E. (Inverted KF wing)
I kiss cut the foam at the dihedral breaks so the original skin serves as the outer side of the fold. On the inner side I de skinned 1/2" back from the fold & glued a 3/4oz fiberglass tape with thinned Aileenes Tacky glue.
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Old 12-21-2007, 05:22 PM
  #170  
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My AUW is 20 oz without the battery. I have a bigger motor and esc than required (cause thats what I had on hand), with the correct components I could easily save 2 ounces.
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Old 12-22-2007, 12:15 PM
  #171  
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I flew again on Friday just before sun down. I really enjoy flying this design. Easy to fly, forgiving yet highly maneuverable.

It is the easiest plane to do outside loops I've ever flown. Loop after outside loop. Easy to do, tight, and tracks dead straight.

I used a 150 watt motor on my build. On a fresh battery I was able to hover. Just barely but it did it!

I flew with an 1100 and 1300 mAh, 3s batteries. I like the lighter battery best. Flight times with the 1100 are plenty long. I didn't time it, but I would estimate at lest 15 min of mostly aerobatic flying. Just floating around level requires very little power.
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Old 12-23-2007, 07:26 AM
  #172  
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Originally Posted by boberos View Post
Here are some details for my Caricorn as seen in the above pics.
The other mod was to add a bamboo skewer between the the floats to prevent fuselage cracking at the dihedral joint.

For the 85% Capricorn:

Control surface Deflections using elevons with a 2" chord.
Low rate 3/4" up & 3/4" down
High rate 1" up & 1" down

Mine flys fine with a 400XT & 3S1200 lipo but needs a 9X4 prop to get unstuck from the grass.
I just weighed mine; 18 oz ready to fly.

Changes for next one.
5 gm servos instead of current 20 gm ones. (Will probably switch servos when next batch arrives, for a saving of 45 gm or 1 1/2 oz.)
Attach floats 1 1/4" farther fwd. Remember I attached these ones assuming a 40%
C of G. Nice thing about foam is that I already cut 1" off rear of step so that it is now near my 28% C of G. Step should be very close to C of G.
I might build it about 5% smaller to reduce drag & increase speed. I don't expect much of a weight saving from using less foam.

All panels are 7" wide so you need a piece of FFF that is 28" wide & 23 1/2" long plus 6" on the other side of the fold.. The natural fold in the FFF serves as my L.E. & it folds 6" back from the L.E. (Inverted KF wing)
I kiss cut the foam at the dihedral breaks so the original skin serves as the outer side of the fold. On the inner side I de skinned 1/2" back from the fold & glued a 3/4oz fiberglass tape with thinned Aileenes Tacky glue.
I didnt realize this was the 80% version.

Looks to me like the fanfold foam works very well for this application. Especially doing the fold over at the front (KF section). Im not so sure the Klien Folgleman effect really contributes much to the airodynamics at these scales, but the structural advantages are very usefull all on thier own

I am not a fan of the skewer between the sponsons, although Jed (and others) has been doing that succesfully from day one on all his.

I prefer the brace piece running down the bottom of the center V. It allows for some give when runniing over rough ground or water and provides a little shock absorbsion effect on rough landings.

Nice job!

Larry
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Old 12-23-2007, 07:35 AM
  #173  
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Originally Posted by leadfeather View Post
I flew again on Friday just before sun down. I really enjoy flying this design. Easy to fly, forgiving yet highly maneuverable.

It is the easiest plane to do outside loops I've ever flown. Loop after outside loop. Easy to do, tight, and tracks dead straight.

I used a 150 watt motor on my build. On a fresh battery I was able to hover. Just barely but it did it!

I flew with an 1100 and 1300 mAh, 3s batteries. I like the lighter battery best. Flight times with the 1100 are plenty long. I didn't time it, but I would estimate at lest 15 min of mostly aerobatic flying. Just floating around level requires very little power.
This thing does some cool inverted spins. With just a little power you can get it to hold altitude and with more it will climb. I like doing slow blenders and low low flips and outside loops. I like hearing the gasps from the peanut gallery when I almost dont make it

I think my favorite manover is still the speed skater turns with it tipped up on one sponson. Those look soooo cool on smooth glassy water.

My latest fun thing is to do a vary slow decent in a very tight turn/spin with some power on. Go all the way down and "land" on one sponson while you continue turning on the ground with one side raised up, then take off again - all without ever touching the other sponson. Ive only managed to pull it off 2 or 3 times, but it sure is cool.

I call that my short field landing approach

Larry
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Old 12-23-2007, 02:49 PM
  #174  
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Hi Leadfeather,

You mentioned in post 170 that you are using a 150 watt motor.
That sounds perfect. What make & model of motor is it?

Thanks,
Bob
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Old 12-23-2007, 05:25 PM
  #175  
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Hi Bob,

I bought the motor off of eBay some time ago. Small company from Hong Kong was making them. No longer available on eBay...I just checked. Too bad it was a good motor; good power to weight, low cost.

I think there are lots of good choices for motors. For the Capricorn you can probably get by with a cheap combo like the one available from Grayson Hobby since you won't be running it hard most of the time.

Dan


Originally Posted by boberos View Post
Hi Leadfeather,

You mentioned in post 170 that you are using a 150 watt motor.
That sounds perfect. What make & model of motor is it?

Thanks,
Bob
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