Easy change balance weight for CG
04-08-2005, 10:39 PM
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Easy change balance weight for CG
I have a H9 Twist that is new. I set it up as manual states with CG forward. I am not yet ready for full 3D set up.
It took several of 4 oz stick on weights to balance. I just epoxed them to bottom of firewall.
So, when time to move the CG backward I have choice to go in steps or all at once.
Changing the amount of weights in steps requires possible removing and re epoxy of some of the weights several times.
(yea, yea, yea I'm lazy)
I am trying to think of way to make weight changes easy yet assure they will not fall off in flight.
This idea could be used on different planes also.
How about some different ideas to do this?
1. Some kind of 'box' to hold different amounts of weights.
2. Drill the weights to screw to the firewall. May take blind nut of back side of firewall.
3. Screw velcro to the firewal and wrap the weights.
Others?
It took several of 4 oz stick on weights to balance. I just epoxed them to bottom of firewall.
So, when time to move the CG backward I have choice to go in steps or all at once.
Changing the amount of weights in steps requires possible removing and re epoxy of some of the weights several times.
(yea, yea, yea I'm lazy)
I am trying to think of way to make weight changes easy yet assure they will not fall off in flight.
This idea could be used on different planes also.
How about some different ideas to do this?
1. Some kind of 'box' to hold different amounts of weights.
2. Drill the weights to screw to the firewall. May take blind nut of back side of firewall.
3. Screw velcro to the firewal and wrap the weights.
Others?
04-09-2005, 02:24 AM
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RE: Easy change balance weight for CG
Didn't your weights come with double sided adhesive tape ? If it isn't working or is hard to remove I would try using shrink wrap after fiquring out how much you need to use and then secure it to the fuse some how.
good luck
good luck
04-09-2005, 10:29 AM
#3
RE: Easy change balance weight for CG
I've had problems with the double-sided tape lasting and epoxying the weights to the firewall are awkward when you want to remove the weight. I prefer screwing the weights to the firewall. I know they'll stay there until I want to adjust the CG.
Mike
Mike
04-09-2005, 10:36 AM
#4
RE: Easy change balance weight for CG
Have you thought about having your battery as far forward as possible when doing your initial balance, then shifting your battery back and/or using a larger battery when you want to change the CG ? Your battery weighs a couple of ounces and if need be you can use an extension on the battery to get it all the way in the tail if you wanted to.
It seems it would be easier to move the battery, especially if you use adhesive velcro strips, than undoing the weights.
It seems it would be easier to move the battery, especially if you use adhesive velcro strips, than undoing the weights.
04-09-2005, 01:53 PM
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RE: Easy change balance weight for CG
I have the battery as far forward as possible. And, as you say it only weighs about 2 oz. I had to put about 16 of the 4 oz weights to make it balance ok. So the battery is only a small part of the solution. And you still have to secure the battery. So, possible best to have simple system to quickly change balance weights.
On another plane I had used the sticky side weights. They all came loose in the air, chipped the prop. I didn't know this until landing. I thought it handled quite a bit different. Lucky to get it down safe in high gusty winds.
Good thoughts guys, thanks.
On another plane I had used the sticky side weights. They all came loose in the air, chipped the prop. I didn't know this until landing. I thought it handled quite a bit different. Lucky to get it down safe in high gusty winds.
Good thoughts guys, thanks.
04-09-2005, 02:44 PM
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RE: Easy change balance weight for CG
dubro has a brass filled 3oz spinner nut - it will fit under a larger spinner - that would give you at least 4 or more oz at the very front - I have a twist with a magnum 52xls with a 1oz dubro spinner nut, my battery is in the fuel tank compartment - no other added weight.
04-09-2005, 07:25 PM
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RE: Easy change balance weight for CG
I have a Simple Staggerwing. It was designed for the OS .10, so when I installed a Norvel .074, it came out light in the nose, so I moved the tank back far enough to GOOP the battery to the backside of the firewall. I refuse to ad dead weight to my planes. Get creative and I'm sure you can eliminate most, if not all need for added nose weight. Do you have sheet tail surfaces? Sheeted fuselage? An ounce lighter tailwheel saves 4 ounces at the nose...
04-09-2005, 07:34 PM
#8
RE: Easy change balance weight for CG
ORIGINAL: fastplane
I have the battery as far forward as possible. And, as you say it only weighs about 2 oz. I had to put about 16 of the 4 oz weights to make it balance ok.
>DuBro makes crankshaft weights in 1 oz and 2 oz sizes.
>They fasten to the engine in place of the washer under
>the prop nut. These weights will USUALLY fit under a
>2 1/2" spinner, possibly smaller depending on the spinner
>shape. A 2oz weight on the end of the crank is worth about
>6 oz on the firewall.
>
>The other thing you can do is use SIG weights. They have
>a hole already in them and you place them
>between the bottom of the motor mount and the nut attached
>to the engine mounting bolt. Again, It gets the weight forward
>of the firewall so you use less weight.
So the battery is only a small part of the solution. And you still have to secure the battery.
>Securing the battery is the easy part. Use strip, self adhesive
>velcro. One adhesive strip you adhere to the battery, then
>velcro the 2nd piece to the piece on the battery. Peel the
>backing away from the 2nd piece and press against a suitable
>surface. When you want to move the battery, just un velcro
>the battery from the piece stuck on the plane. Put a new 2nd
>piece on and repeat in the new location.
So, possible best to have simple system to quickly change balance weights.
On another plane I had used the sticky side weights. They all came loose in the air, chipped the prop. I didn't know this until landing. I thought it handled quite a bit different. Lucky to get it down safe in high gusty winds.
Good thoughts guys, thanks.
I have the battery as far forward as possible. And, as you say it only weighs about 2 oz. I had to put about 16 of the 4 oz weights to make it balance ok.
>DuBro makes crankshaft weights in 1 oz and 2 oz sizes.
>They fasten to the engine in place of the washer under
>the prop nut. These weights will USUALLY fit under a
>2 1/2" spinner, possibly smaller depending on the spinner
>shape. A 2oz weight on the end of the crank is worth about
>6 oz on the firewall.
>
>The other thing you can do is use SIG weights. They have
>a hole already in them and you place them
>between the bottom of the motor mount and the nut attached
>to the engine mounting bolt. Again, It gets the weight forward
>of the firewall so you use less weight.
So the battery is only a small part of the solution. And you still have to secure the battery.
>Securing the battery is the easy part. Use strip, self adhesive
>velcro. One adhesive strip you adhere to the battery, then
>velcro the 2nd piece to the piece on the battery. Peel the
>backing away from the 2nd piece and press against a suitable
>surface. When you want to move the battery, just un velcro
>the battery from the piece stuck on the plane. Put a new 2nd
>piece on and repeat in the new location.
So, possible best to have simple system to quickly change balance weights.
On another plane I had used the sticky side weights. They all came loose in the air, chipped the prop. I didn't know this until landing. I thought it handled quite a bit different. Lucky to get it down safe in high gusty winds.
Good thoughts guys, thanks.
04-10-2005, 08:17 AM
#10
My Feedback: (15)
RE: Easy change balance weight for CG
I use Campy layout but I will ad I also use "industrial strength velcro , you can get 5ft length in a small box at Walmart for a great price .
IN addition If I have a choice of adding weight , I will go to a bigger battery first before going to dead weight .
IN addition If I have a choice of adding weight , I will go to a bigger battery first before going to dead weight .
04-10-2005, 08:52 PM
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RE: Easy change balance weight for CG
I also have a twist 3d what i did is put the reciever and the battery as far forward up against the wall of the fuel tank, One on top of the other with 1/4 in foam in between and compressed it down with the wing. That will hold most of the weight up front, on mine i had to add a 2.5 oz brass spinner nut to hold on the prop then put on my regular 2 1/4 in plastic spinner to cover it up. I still needed 3/4 of an oz more weight to balance at 4 1/4 inch from the leading edge. To solve this i used 1/4 oz lead self adhesive weights that come in strips of 8. i cut out 3 of the eight leaving them attacted together dont take the paper backing off the lead. i drilled a hole in the middle square and used a small screw and lock nut to hold the lead in place on the plane . I drilled a small hole on the very front of the balsa by the prop this is to get most of the weight torward the front this equalls less weight. (Not on the firewall, farther forward ) install the lead on the inside wall, this way you can add more weight or take weight off by simply unscrewing the screw and putting a bigger strip of lead. If you need more weight put another screw on the other side and do the same thing to level out the weight from right to left. By leaving the paper off the lead you dont have to worry about it sticking to the wood. I hope this answers you question. This was the best way i found to add and remove weight to alter the cg.
