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-   -   Adding Weight (http://www.Wattflyer.com/forums/showthread.php?t=73657)

garyp1029 04-29-2014 06:41 AM

Adding Weight
 
If one has a plane which needs nose weight, is it a bad idea to simply add weight to the forward end of the battery itself. The plane is a Electrifly Super Sportster rxr. The battery takes up all the available space in the front compartment; there is no room for a larger battery, and the tail can not be lightened. The idea is to tape a washer(s) of sufficient weight to the top of the battery to balance the plane. If solidly attached, is there any danger in doing this? Thanks. Gary

CHELLIE 04-29-2014 07:44 AM

Quote:

Originally Posted by garyp1029 (Post 946812)
If one has a plane which needs nose weight, is it a bad idea to simply add weight to the forward end of the battery itself. The plane is a Electrifly Super Sportster rxr. The battery takes up all the available space in the front compartment; there is no room for a larger battery, and the tail can not be lightened. The idea is to tape a washer(s) of sufficient weight to the top of the battery to balance the plane. If solidly attached, is there any danger in doing this? Thanks. Gary

If you have to add weight, its best to apply the weight to the airplane, so its always there, applying the weight to the battery wont hurt untill you forget, and install a battery that does not have the additional weight added to it, a good place to add the weight would be to the boxed motor mount, i would epoxy the weight on.

http://www.towerhobbies.com/products...a1161b_550.jpg

fhhuber 04-29-2014 08:07 AM

If you need weight in the nose put it as far forward as you can. this might include using a brass "acorn" style prop nut inside the spinner.

The further forward the weight the less you will need.

solentlife 04-29-2014 09:52 AM

Quote:

Originally Posted by fhhuber (Post 946817)
If you need weight in the nose put it as far forward as you can. this might include using a brass "acorn" style prop nut inside the spinner.

The further forward the weight the less you will need.

Very true ...

But .... also take in mind moment arms and pendulum effect.

If you add a large amount to an extreme - you can actually create a problem. Yachts, ships really suffer this badly if poorly done.
What happens is the weight balances everything .. but in motion can create strong even violent pitching actions. Greater weight nearer the CoG actually softens this ...

So in extreme weight situations try to find why you need such corrective weight, try to make it work for you and not be a dead weight.

Nigel

Chucksolo69 04-29-2014 05:37 PM

Quote:

Originally Posted by garyp1029 (Post 946812)
If one has a plane which needs nose weight, is it a bad idea to simply add weight to the forward end of the battery itself. The plane is a Electrifly Super Sportster rxr. The battery takes up all the available space in the front compartment; there is no room for a larger battery, and the tail can not be lightened. The idea is to tape a washer(s) of sufficient weight to the top of the battery to balance the plane. If solidly attached, is there any danger in doing this? Thanks. Gary

Is this plane the 40" foam Super Sportster? This is really curious because I fly mine with an 1800 3S 20c Flyzone battery pushed all the way forward and the CG is spot on. I have no elevator down trim and she flies straight and true at half throttle. Remember, the plane is supposed to climb at full throttle and mine does so, although not severely.:tc:

garyp1029 04-29-2014 06:43 PM

Yes, that is the plane. I am using 1500 20C batteries and the plane seems SLIGHTLY tail heavy with the battery all the way forward, but the plane has yet to fly. I am new to electrics (the Apprentice is my first plane; the SS rxr is the second) but I remember from my nitro days (over 20 years ago) that if one was uncertain, it was best to go a little nose heavy. You may well be right. The el cheapo elevator clevis seems to be disintegrating, so before I fly I am going to replace both the rudder and elevator clevises with something more substantial from Dubro. As you know, the only way of adjusting rudder and elevator throws is by losening the rods at the servo end, a very unsatisfactory set-up. Gary

Chucksolo69 04-29-2014 09:38 PM

Yes, with 1500 it will probably be tail heavy. That's too bad about the clevises. Mine are rock solid. I also like the Dubro style connectors on the servos. Mine flies great.

solentlife 04-29-2014 09:47 PM

I have developed a liking for the screw type capture links. The rod passes through and you can adjust as you like and screw up the grubscrew ..

Just means on some models changing the rods as you need longer to reach the screw fitting ..

I avoid as the plague having adjustment inside the model .. preferring Z bends to servos in there.

Nigel

Chucksolo69 05-01-2014 09:00 AM

Quote:

Originally Posted by solentlife (Post 946866)
I have developed a liking for the screw type capture links. The rod passes through and you can adjust as you like and screw up the grubscrew ..

Just means on some models changing the rods as you need longer to reach the screw fitting ..

I avoid as the plague having adjustment inside the model .. preferring Z bends to servos in there.

Nigel

Yep, agree on all points.;)

road king 97 05-01-2014 06:02 PM

Most times Great planes is pretty close i would think about getting the cg correct with recomended parts used . Did you change the motor size or anything else on it ?

thepiper92 05-01-2014 06:37 PM

I like gold n clevises from Sullivan. I use their nylon push rods and you just need to thread in a metal rod and the clevise screws on easily. To adjust I simply just take off the control horn from the servo, and turn the clevise, or turn the rod itself to adjust the other clevise. To test, just put the horn back on the servo where it was, preferably with power on so the servo won't move when I unscrew the horn.

garyp1029 05-01-2014 06:47 PM

I made a mistake above--the battery is a Turnigy 1600, not a 1500. With the battery as far forward as possible, several checks show the plane needs almost exactly 1 1/2 ounce on the front of the battery to balance at the stated CG. I went to ACE hardware with my kitchen scales, weighed several large nuts, and bought 4 (the number of batteries I have) which, when added to the front of the battery) provides exact balance. I will permanently attach a nut to only one battery and test fly to see how the plane reacts. If all pans out well, I will then attach the nuts to the remaining batteries. Thanks for all the suggestions and ideas. Gary

solentlife 05-01-2014 06:53 PM

Quote:

Originally Posted by garyp1029 (Post 947009)
I made a mistake above--the battery is a Turnigy 1600, not a 1500. With the battery as far forward as possible, several checks show the plane needs almost exactly 1 1/2 ounce on the front of the battery to balance at the stated CG. I went to ACE hardware with my kitchen scales, weighed several large nuts, and bought 4 (the number of batteries I have) which, when added to the front of the battery) provides exact balance. I will permanently attach a nut to only one battery and test fly to see how the plane reacts. If all pans out well, I will then attach the nuts to the remaining batteries. Thanks for all the suggestions and ideas. Gary

May I suggest Self Adhesive Wheel Weights .. used by local Tyre fitters to balance your cars wheel ?

I have a pal with a Tyre shop .. he gives me a handful every so often. They are marked with the weight etc.

I would also suggest that weights are better fixed to the model not to the batterys. Imagine a crash and battery ... a weight on firewall is better than a weight fixed to covering of a LiPo.

Nigel

road king 97 05-01-2014 07:34 PM

I have had double sided tape come loose when using weights so i epoxy lead fishing weights in so they wont move around . You can mix buck shot with epoxy also . joe

solentlife 05-01-2014 07:50 PM

Quote:

Originally Posted by road king 97 (Post 947012)
I have had double sided tape come loose when using weights so i epoxy lead fishing weights in so they wont move around . You can mix buck shot with epoxy also . joe

True .. I usually put a thin smear of epoxy where I want a good adhesion of tape. Once cured - it provides a much better grab than foam .. especially if you make the epoxy patch larger.

In servo holes .. I pour in epoxy .. mix .. let it flow to fill the nooks and crannys .. smear it up the sides etc. It doesn't take much to create a flat excellent surface for servo tape to adhere to.

I would rather a weight come away from the foam than pierce a LiPo ...


Nigel

thepiper92 05-01-2014 08:06 PM

I feel tape alone is more or less for testing placement of weights, so it sticks enough to test cg, but can be moved around. Another good glue is canopy. I used it for making canopy on p47, and it adheres bombs and exhaust to canopy. I used it for gluing esc and receiver down as well. A strong hold but can be removed if I give a couple tugs. It's workable and doesn't stick to fingers, almost like standards white craft glue, plus it dries clear. I have yet to stick to foam, but from what I can tell, it wouldn't harm foam. It was a very good find and I suggest it to be a glue everyone should have for repairs and adhering parts. It is a tad runny tho, but can do wiped off with your finger, unlike ca glue and the like.

fhhuber 05-01-2014 08:21 PM

Attach the weight to the airplane... not to the battery.

You are limiting the batteries to being used in that one plane if you are weighting them for the plane.

solentlife 05-01-2014 09:36 PM

Of course if you really worry about wheel weights or similar coming away with just tape or glue ...

Drill a small hole through the weight .. epoxy a cocktail stick through the hole .. and then glue that and weight into / on the model. Or as my mate does - he passes a thin long self-tapper through with epoxy glue on - so weight AND threads are glued to model.

Nigel

kyleservicetech 05-01-2014 11:44 PM

Quote:

Originally Posted by solentlife (Post 947030)
Of course if you really worry about wheel weights or similar coming away with just tape or glue ...

Drill a small hole through the weight .. epoxy a cocktail stick through the hole .. and then glue that and weight into / on the model. Or as my mate does - he passes a thin long self-tapper through with epoxy glue on - so weight AND threads are glued to model.

Nigel

Way off track, just don't run a self tapping screw through your lead weight into your battery pack. :D :D :D

thepiper92 05-02-2014 02:16 AM

Nothing with a few breathing holes in your lipos :p>

propnut48 05-02-2014 08:18 PM

I also have the Super sportster and have never had an issue with balance. I have actually added a slight amount to the tail to make it a little more responsive.


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