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CL-415

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Old 12-02-2010, 04:30 PM
  #51  
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Default RE: CL-415

BM:
Is there a way to increase our wing size without screwing everything up?
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Old 12-02-2010, 08:02 PM
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Default RE: CL-415

Not by more than one rib bay.  The design of any airplane is a delicate balance.  Start messing around with any one part and other factors get messed up real quick.  Stability issues being a big one.

If your team hasn't gotten too far into the construction phase yet then cut your losses and get the plans enlarged by about 15 to 18%.  That will bump up the span only about 10 inches but the wing area will go up by the square to around 730'ish depending on your final enlargement value.  At this sort of enlargement only a few parts will need to be made from the next thicker sheet balsa.  The rest can stay as they are with no real penalty.  But with a 35 to 40% increase in wing area you'll have a bigger % of the model weight to work with as payload.  Also thanks to our old friend Reynolds and his numbers the bigger size will carry a somewhat heavier wing loading with grace.  So your max allowbable weight will be more than the increase in wing area would indicate.  You'll be able to build to a 7.5'ish lb overall weight instead of around a 6.75 lb weight that you'd expect for a 1.35 time increase in wing area.

If your airborne payload still won't fit within that sort of model to payload weight budget then you'll need to either make the payload lighter or dump the idea of using this design since you can't stretch it more than this without major structural changes to where it's a whole new design.  As it is jumping up by 1.18 would need stouter main wing spars, using the thickness in the tails that the scaling up indicates and likely you'll want to sheet the wing out to the motor nacelles to add a bigger measure of torsionaly stiffness.  For landing on water at this weight the bottom of the hull and half way up the sides would need to be sheeted with 1/8 medium to medium hard sheeting to withstand the impact of water landings.  As well the fuselage framing would need to be done using very hard higer density wood to retain proper strength in the parts that are only wider but not thicker.
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Old 12-03-2010, 04:37 AM
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Default RE: CL-415

The RCM Plans would be in the size range you recomend BM, although it's a 215,,these are the plans I enlarged for mine
http://www.rcmplans.com/index.php?ma...oducts_id=1739

There is also a free cl-215 CAD download here, It larger, but could be scale up/down easy in CAD
http://plans.am.free.fr/
http://plans.am.free.fr/plans/canadair.zip
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Old 12-03-2010, 04:52 AM
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ORIGINAL: SPS Aeronautics

We're thinking about using two pneumatics to open and close the nose doors. Any advice/suggestions on how to make it work? Here's the website: http://www.firgelli.com/products.php
Those are the electronic actuators I posted earlier,, not pneumatic

Plus/minus of each

Pneumatics,
pluses,
Water doesn't affect them cylinder can come into contact with water so mounting location options are somewhat easier

Minuses,
* number of open/close cycles is limited by how much air you can store
* pneumatics are less accurate as far as being able to control speed of doors opening and closing, they tend to slam open/close and not operate smoothly


Electronics,
Pluses
* cycles is virtually only limited to your operation time aka battery life cycle
* speed of operation is more controlled and predictable

Minuses
* Must be water proofed which is not that difficult really, just can't come in direct contact with water. so the mechanics/linkages are more complicated

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Old 12-03-2010, 06:33 PM
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Scaleonly4me: I think we have to go with the actuators you recomended as they save a lot of weight in comparsion to the pneumatic. We are going to use 2 to open and close the door, 1 for the front landing gear, and 1 for the rear landing gear.
BM: In response to the the wingloading. I talked to an aeronautic engineer today, and he said that more power produces more lift. I am thinking that if we just bulked up the engines a little bit, it should work...might not be enjoyable, but it sould work...What do you think
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Old 12-04-2010, 05:45 AM
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Default RE: CL-415

Well, honestly the actuator idea was only for the function of lifting/lower the nose of the plane if necessary, putting 4-5 of those where the might come in in contact with water could be catastrophic,,, one of those shorts your system in flight,, it's game over

If it were me I'd use a retract or programmable servo (to adjust speed) and rig a double push/pull linkage to operate the clam shell function keeping that servo well inside the dry area of the fuselage, and use commonly available R/C pneumatics for the landing gear which can get wet and not affect the radio gear.

Remember, with a float/sea plane your biggest concern is keeping the radio equipment dry
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Old 12-04-2010, 09:00 AM
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Default RE: CL-415

If you're worried about weight more than scale, make the wing longer.
With that Hershey bar wing, more span won't be all that noticeable.
This is a Goldberg Mirage.
Kit span is 54".
It will fly with a 76" wing also, with no changes to anything else.
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Old 12-06-2010, 08:37 AM
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Tall Paul: There is one thing that cant understand...The all up weight that the plan's provider gives is 2900 g (6.4 lb) however thecalculatedmax wing load of the plane is 5 lb...arewing-loadand AUW totally different or should i be worried?

SO4M: I agree with you about rigging the push pull linkage. however, pneumatics are so heavy...you have to have an air tank on board...Yes, the advantage about not having to worry about getting them wet is huge....
maybe we can use this...http://www3.towerhobbies.com/cgi-bin...?&I=LXET21&P=V ....it looks alot smaller and lighter than the pneumatics that we already own
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Old 12-06-2010, 08:47 AM
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Default RE: CL-415

Wing loading is usually AUW and all the wing area.
16 oz per sq. ft. is a somewhat heavy loading, but still reasonable.
Looking at your figures and desires, I'd say your airplane is too small.
For all the stuff you want to put in it, getting a reasonable wing loading might compromise the structure to get a reasonable loading.
The fuselage is going to be heavy.
Adding span won't hurt anything other than the scale thing.
How important is that?
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Old 12-06-2010, 08:58 AM
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Default RE: CL-415

The most important thing is that the plane can fly...if that means sacraficing scale...then i am ll for it...So your saying that if i increase the wing span that would help?
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Old 12-06-2010, 09:00 AM
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Default RE: CL-415

The most important thing is that the plane can fly...if that means sacraficing scale...then i am ll for it...So your saying that if i increase the wing span that would help?
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Old 12-06-2010, 10:53 AM
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Yes, and yes.
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Old 12-06-2010, 04:41 PM
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Default RE: CL-415


ORIGINAL: Tall Paul

Wing loading is usually AUW and all the wing area.
16 oz per sq. ft. is a somewhat heavy loading, but still reasonable.
Heavy?
16oz is between a trainer and a glider, a 40 size trainer is inthe 20oz range, a 40-60 size warbird is in the 30oz range.

I agree slightly larger would make it easier to squeeze everything in, but that size plane would fly fine in the 30oz range. And with those big flaps take off/landing speeds would be no problem.
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Old 12-06-2010, 05:16 PM
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Default RE: CL-415

These guys are newbies.
30 oz loadings are for experts.
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