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GeorgeInNePa wrote:

mwloveslm wrote:wow nice....ok....do you think it might be possible for us to see a top view? If it's not a problem for you.....

That's a pic of a broken one from Tuesday.

I'll get some pics of the competition boom tomorrow...

okay thank you! ahaha

I know it's a little late and all... but one suggestion is to get rid of the vertical piece near the testing wall, it's not really doing much more than keeping the base and the tube separate, right? My boom's have had some pretty weak tension members and I've gotten used to keeping it on the same jig I used to build it until we reach the competition, once we're there I either have the boom laying on it's side or it's on the testing wall and I use the bottom line to space them properly, and once the loading block's on there it doesn't go anywhere. From the looks of your member it might save you .25 or .5 grams

Other than that, it looks really nice! Thanks for the pic.

iwonder wrote:I know it's a little late and all... but one suggestion is to get rid of the vertical piece near the testing wall, it's not really doing much more than keeping the base and the tube separate, right? My boom's have had some pretty weak tension members and I've gotten used to keeping it on the same jig I used to build it until we reach the competition, once we're there I either have the boom laying on it's side or it's on the testing wall and I use the bottom line to space them properly, and once the loading block's on there it doesn't go anywhere. From the looks of your member it might save you .25 or .5 grams

Other than that, it looks really nice! Thanks for the pic.

A picture is, indeed, worth....a lot of words; thanks for providing, George. A nice piece of work!
iwonder is right about the vertical. Helpful in setting up on the wall, but that setup can indeed be done w/o it, and it just adds weight.
Hard to tell- is the tension member square cross-section or a dowel (round)?

Absent the vertical at the wall, the appearance is quite similar to ours. Differences are a 1/4 wide x ~1/32nd thick t-member, in hickory instead of bass, a slightly different treatment at the bolt block, and at the wall end of the tube. At our State tournament we saw a couple variations. The B-team that won was running a setup very similar to ours- machined tube, slightly different wall bolt block setup. Second place (who won regionals) was running rolled tube about the same diameter...low density (square x-section- end grain orientation) blocks at both wall and distal ends that the tube fits in to, bass t-member. Third place C-team was running something very similar to that. Second place C-team was running a larger diameter, rolled tube.

The question I'm not sure of the answer to is how far a tube approach can go, compared to a "conventional" design. Our boom kids were really limited on time this year. Both teams only built one regional and one state boom, and the only test outside of competition was one of the regional booms taken to 12.5kg. The design calculations suggest a B-version in the 2,000 range is possible. We'll see what can be done in the next few weeks....

Balsa Man wrote:

iwonder wrote:I know it's a little late and all... but one suggestion is to get rid of the vertical piece near the testing wall, it's not really doing much more than keeping the base and the tube separate, right? My boom's have had some pretty weak tension members and I've gotten used to keeping it on the same jig I used to build it until we reach the competition, once we're there I either have the boom laying on it's side or it's on the testing wall and I use the bottom line to space them properly, and once the loading block's on there it doesn't go anywhere. From the looks of your member it might save you .25 or .5 grams

Other than that, it looks really nice! Thanks for the pic.

A picture is, indeed, worth....a lot of words; thanks for providing, George. A nice piece of work!
iwonder is right about the vertical. Helpful in setting up on the wall, but that setup can indeed be done w/o it, and it just adds weight.
Hard to tell- is the tension member square cross-section or a dowel (round)?

Absent the vertical at the wall, the appearance is quite similar to ours. Differences are a 1/4 wide x ~1/32nd thick t-member, in hickory instead of bass, a slightly different treatment at the bolt block, and at the wall end of the tube. At our State tournament we saw a couple variations. The B-team that won was running a setup very similar to ours- machined tube, slightly different wall bolt block setup. Second place (who won regionals) was running rolled tube about the same diameter...low density (square x-section- end grain orientation) blocks at both wall and distal ends that the tube fits in to, bass t-member. Third place C-team was running something very similar to that. Second place C-team was running a larger diameter, rolled tube.

The question I'm not sure of the answer to is how far a tube approach can go, compared to a "conventional" design. Our boom kids were really limited on time this year. Both teams only built one regional and one state boom, and the only test outside of competition was one of the regional booms taken to 12.5kg. The design calculations suggest a B-version in the 2,000 range is possible. We'll see what can be done in the next few weeks....

The vertical is there to give two nervous 13yo girls one less thing to worry about. It made from very, very light balsa, so it doesn't add much at all.

Tension member is square cross section.

We're scheduled for the 9:00-9:50, so I'm on edge...

Totally understand (on the vertical)
GOOD LUCK! Can't wait to hear...

The boom weighed 10.49grams.

13100grams held.

1248.81 efficiency.

It sheared one of the "wedges" on the tension arm. The tube could have held more.

I'm happy! It probably won't win, but I'm proud of the girls!

GeorgeInNePa wrote:The boom weighed 10.49grams.

13100grams held.

1248.81 efficiency.

It sheared one of the "wedges" on the tension arm. The tube could have held more.

I'm happy! It probably won't win, but I'm proud of the girls!

A very respectable score; you should be proud of them- pass on my congratulations to them, please.
Do you know what your bare tube weight was?

Balsa Man wrote:

GeorgeInNePa wrote:The boom weighed 10.49grams.

13100grams held.

1248.81 efficiency.

It sheared one of the "wedges" on the tension arm. The tube could have held more.

I'm happy! It probably won't win, but I'm proud of the girls!

A very respectable score; you should be proud of them- pass on my congratulations to them, please.
Do you know what your bare tube weight was?

4.3g on my $9 Harbor Freight digital scale.

The boom weighed 10.6 on the same scale, for comparison.

Thanks.
"The numbers" definately indicate a tube at 1/16th wall, at that weight, could hold all, w/ a significant safety factor.
Hope that score holds up for a medal.

Balsa Man wrote:Thanks.
"The numbers" definately indicate a tube at 1/16th wall, at that weight, could hold all, w/ a significant safety factor.
Hope that score holds up for a medal.

We'll do some experimenting over the Summer for next year. We need to perfect our mount and work on a jig for aligning the holes.

I heard Shady Side just went over 1600 in the second time-slot...

ETA:
Ours was good for for 3rd, behind Shady Side and Strath Haven (13xx)...