Molded Supra

[Soarkraut]

I recently purchased a new molded Supra from Kennedy. I got the 2.4, kevlar front end..
Some one advised me to glue in the Ballast tube, glue it as a structural fuselage component.(not just so it stays put)
There are no factory recommendations, none that I can find.Nothing on the web, nothing I have found this far. :confused:
Could some of the experts out there comment on this ??

Pete in Delaware

[peterkim2]

http://www.hilaunch.com/Supra%20Inst.htm

[aeajr]

peterkim2, I see no reference to the gluing of the ballast tube or its use as a structural component at the link you posted.\


Pete, I have a molded Supra, but mine is an earler version.

I have heard the same as you, that there is great benefit to installing the ballast tube permanently. And, that it should be done with extra attention on the 2.4 friendly to use it to provide extra structural integrity.

Since I did not build mine, I got it used, I can't tell you what that means exactly but I would think that it means you need to be sure to glue the inner end of the tube so that it is bonded within the fuselage rather than just supported.

I have heard, but can not cite documentation, that the 2.4 fuse is strong, but not as strong as the carbon fuse. If you have a tendency to land hard on the nose that the 2.4 will be more subject to cracks or breakage. Bonding the ballast tube adds to the strength.

Wish I could be of more help but that is as much as I know.

One other thought, I don't have a nose skeg on mine. I have a mid skeg. Not quite as pinpoint accurate as the nose skeg but I feel it puts less stress on the nose and front of the fuse. I have mid skegs on all three of my competition planes.

Congratulations on getting your Supra. You will love it!

[DProseus]

Pete,

I have Supra #460 and glued my balast tube in. I am not sure how that improves structural integrety as the tube is held by only two points. One is a metal bracket in the aft end of the pod that really is not easy to glue and the second is the bulkhead where you insert it. I glued it there with Goop. If you have epoxied the tail boom to the pod properly, your fuse should be adequately strong.

I would want the balast tube securely fixed in some manner so all that weight will not shift, especially during a hard landing (dork).

Dick

[tonyestep]

The ballast tube won't make the plane's structure stronger. However, the tube's points of attachment can get some heavy loads.

If you have ballast in the tube and you land abruptly, the resulting forces are like a hammer-blow on key spots in the tube. First, the ballast will bang up against its retaining pin. Then the pin will pull the tube forward. Talk to your buddies and you'll hear plenty of stories of the pin being torn out and/or the tube popping free and sliding forward.

The way to defend against this is to spread these loads over as wide an area as possible. A fat retaining pin, well anchored at both ends, and several points of attachment for the tube, will keep everything intact on a hard windy-day landing.

[will_newton]

glue it in if you intend to use it. if you never plan on ballasting, then don't bother installing it.

does it NEED the tube installed or risk the certain death of your plane?

no.

[Robglover]

I've currently got 3 Supras and have built several more for others. I prefer a removeable ballast tube. It can be made to work well either way.

[slozuke]

Why would you NOT glue it in? If you don't need ballast, simply remove the BALLAST from the tube and viola, it's empty! Need ballast? Put it in!
Why remove the whole tube? Weight savings? Oh, that will make a difference. You aren't going to use the space for anything anyway so what's the purpose?
Do you remove the bed of your truck just because you're not carrying anything in it?
I glued mine in to make it the most secure to handle the load of ballast on hard landings. Both my Supra and AVA use the same ballast system. Simple.

Brian

[jtlsf5]

Why would you NOT glue it in? If you don't need ballast, simply remove the BALLAST from the tube and viola, it's empty! Need ballast? Put it in!
Why remove the whole tube? Weight savings? Oh, that will make a difference. You aren't going to use the space for anything anyway so what's the purpose?
Do you remove the bed of your truck just because you're not carrying anything in it?
I glued mine in to make it the most secure to handle the load of ballast on hard landings. Both my Supra and AVA use the same ballast system. Simple.

Brian

Brian,
Working on a Supra with a glued in tube makes any modification/repair almost impossible. There is virtually no way to do anything without significant de-construction. I've flown both my Supras with the ballast tubes not glued in, and the tube anchored via hold down bolt to a block that is glued to the underside of the angled plate that the tube slides through. Very secure, yet removable for dealing with antennas (some of us still use 72 ;) ), changing out a wire harness, etc. One of my Supras is from before the alignment rings were included. Still rock solid, and this plane was flown for 10 rounds with a load of ballast at the first Soaring Masters.

I also find that the tubes are fine for their purpose, but aren't a significant structural element. Gluing them in may help a little, but not enough to offset the problems noted above.

JT

[Robglover]

Brain -

The ballast tube weighs something. Not much, but it's heavier than not having it in the plane. Light is good, sometimes. It's easier to lose 10 5 gram weights than it is to lose one 50 gram weight in a model airplane. The ballast tube is an easy way to lose a few grams.

It's easier to add weights to the tube if the tube is out of the plane. I can walk back to my van in the pit area, grab the tube, add whatever weights I think I need, and walk out to the staging area to add the tube with weights to the plane. I'd prefer to avoid wandering back through the pits at a large contest with a fully assembled unlimited plane whenever possible.

I've had occasions where I needed to get into the fuselage aft of the bulkhead for repairs or modifications to the towhook or wiring harness. If the ballast tube is out then I have another hole to work through.

I've never had a problem with the removable tubes moving in flight or due to a hard landing.

If you want to keep mounting your ballast tube permanently in your Supra you have my permission to do so. I'll try and get over it. I'm going to keep on doing them the way I've been doing them, sorry if it causes you any grief. I don't currently have a truck, but I do remove the seats in my minivan most of the time because I haul stuff like model airplanes and bicycles around a lot.

[slozuke]

You have a good point Jim! I haven't had the mis-fortune to need to do repairs so I've never looked at it from that point of view. As far as grams and walking distances, to each his own I guess.
But thanks for your permission Rob, I'll sleep better now. :rolleyes:

[will_newton]

a few more posts and this thread is going to turn into, "Where you can stick your :censored: ballast tube when you're not using it and will it fit up there sideways"

:D

[aeajr]

a few more posts and this thread is going to turn into, "Where you can stick your :censored: ballast tube when you're not using it and will it fit up there sideways"

:D

Having a stressful day, are we? :rolleyes: