How to add ballast to fibreglass floats?
 

I have a set of Maxford USA fiberglass floats on my CG Piper cub, the CG needs to be moved forward to get it to balance, I flew the cub once and it was too tail heavy but flew fine except for the CG.

What will be the best way to add ballast to the front of the fiberglass floats to get the CG to move forward.

Thank you in advance.

Perhaps its a little late now but a common method I have used on quite a few of my float planes is to simply drill a hole on the top deck in the bow even slightly in front of the propeller. Then if it is hollow there just bundle up your weights and insert then epoxy to the internal structure. finish up with a small patch of monocoat. Quick and easy also easy to make adjustment later.

Adding weights to the float is a much better method since it allows quick change between floats and wheels with out the need to rebalance assuming the airplane was already balanced on wheels. With most twin float conventional designs changing from wheels to to floats will require some forward weight if the step is located at or just behind the CG where the airplane flew well on wheels.

John:cool:

http://www.rcuniverse.com/forum/atta...mentid=2142235

Can you easily move the battery to the front and mark where it was so it ca be moved back with wheels on? Or add some weight to the firewall in a way that it can be easily removed when going back to wheels.
You can always epoxy some weights to the tops of the floats but that usually looks terrible. A more detailed way would be to cut and fashion a removable hatch on top of each float between formers, build a box inside ,add the weights and seal it up.

Huh, sorry Brian that is decidedly not what I said. I doubt you even read my post! I answered CARS11 question in my very first sentence with one quick and easy method to add weight to the 'Floats Bows'. Then in my second paragraph when on to explain how to position floats and by adding weight only to the floats one will never agine be bothered rebalancing every time one makes the switch.

John

Get a dive bag, its got real lead shot in it.

Figure out how much weight you need. I tape a small paper cup to the front and add lead shot till it balances.

If you don't have one, make a hatch or drill a hole that you can patch up later.

Mix the lead in two equal batches with 30 minute epoxy, you'll need a little less lead to make up for the weight of the epoxy.

Pour it in and stand the floats on their nose till it cures.

Patch the holes.

Fixed it for you John. Hope you feel better!

http://www.rcuniverse.com/forum/atta...mentid=2142448

Daughter came with me to the float fly early in 2015.

John, to answer your questions, yes the cub has flown on wheels a few times before and the step is just past the CG also the floats are hollow, I was about to just glue some of the ballast strips to the front of one of the floats since I didn't get a response for over a week.

I like John's and BH's recommendations to cut a round hole on top of one of the floats to epoxy the necessary amount of lead inside the float, will a 1/2 inch hole be big/small enough?

Hey Carlos perhaps your daughter will soon be a future float flyer with you. What a wonderful way to enjoy your float trips.

Yes a half inch hole is likely plenty and I have done some even slightly larger. What is really going to drive the hole size is how creative you get and how much as well as what type of weight you are going to use. I have used lead shot in baggies then ca or epoxied in and used tire weights halved or quartered even in a pinch a steel bolt or two. Its really up to what ever is handy.

As posted before I have never used much more than maybe two or three ounces for the typical size and type airplane such as yours. That may sound like a whole bunch but remember whatever it takes to balance it that with the moment arm so much further forward that it takes far less weight to acheve that original balance point than just around the firewall.

I hope this helps a little and you have good success and love it as much as I do:cool:

John

Yes indeed, it would be nice to have her fly float airplanes at the events with me :)

Yes, all this will help me get the cub balance forward, I will be doing that this weekend and will post some pictures of the process.

Thank you to all that replied to my question.

I finally added the ballast to the floats or float ( left one ) it took around 5 1/2 ounces, the Cub now balances right on the center of the spar with a tad of nose down.

Cut a 3/4" hole on the front top, dropped in the pieces of lead and added 5 min Epoxy and left it standing for about an hour to dry, so far the ballast is not moving, the last thing to do is to close the hole with monokote film.

Will post some pics this weekend.

Was the right side heavy to begin with?

I don't believe so but the OS 70 four cycle is hanging of the right side of the cowl, It may not make any difference to have added the ballast to the left float but just in case :)

Some guys are more anal than others,, after all , it's a model airplane,, not a Swiss watch,, right? ;)

I suppose so, I always say "its just a model airplane, fly the heck out of it " :)

Excellent Cars and yes ballasting only the left float with a side mounted engine is good common since and I have several like that. Now by balancing with the lead in the very tip(s) of the float you will not have to re balance the airplane when you go back to wheels each time.

Enjoy

John

Thank you for all the help John.
Our first float fly is at the end of April, I wanted to be ready ahead of time.

Add the weight to the nose of you plane since it will take less there than on your floats or about the same . joe

..

Sorry Joe you have that exactly backwards. The further forward any ballast added will reduce the required amount of ballast. The bows of the floats on any proper twin float installation is even further forward of the propeller. Adding ballast back in the airplane will only increase the amount needed.

Also if one still wants to add ballast to the airplane only it will increase the amount of ballast needed as well as loosing the ability to quickly change back and forth from floats to wheels easily without rebalancing every time. If that is what one wants but I don,t believe it was the case with this OP.


John

Not sorry for me but i have installed around 40 or 50 sets of floats from half A models to 1/3 cub 4ft EDO scale floats and not one made the airplane tail heavy ,not sure why his are but i think i would look into that first. The way i look at weights in the tip of the floats is much more damage it could do if you ever dig one in or weight shifting unless its epoxied in place .

BTW i think i know a little about flying off of water since i have only flown off of water for the last 20 years . .lol joe

Sir I have no intention of engaging in a 'Battle of the Bios'. That serves only to discredit both parties.

However back to the subject. The 'Bows' is the key word here and if one assumes the ballast is placed in the bows which are forward of the propeller in the op's airplane and as I recommended Then your statement above is incorrect. In fact quite the opposite is true. The further forward the ballast is placed will in effect reduce the required amount of ballest.

John

If the planes CG was ok to begin with then adding floats should not have changed that so either its the floats making it tail heavy or the plane is . You get it ? You said yourself the float tips stick out further that the prop and your reasoning for putting weights there ? Whats wrong with this picture kinda thing ? take a look http://www.seaplanesupply.com/faq.htm

Joe, not sure why you're arguing so hard,, this statement is wrong, since the float extent out further than the fuse, it will take less weight to balance adding to the floats, can't dispute the physics of that.

Arguing whether a plane should be nose or tail heavy after adding floats??? That's a completely different conversation,,, well that would depend on the float's design of course. But it's been my experience, that since most of the mass of the float is forward of CG, Yes it tends to make them nose heavy more often. But things like water rudder linkages, extra mounting hardware for the rear float struts can shift the CG back too, there's never one answer for every design.

Why the plane needed nose weight is irrelevant to his question on how to best balance it