Originally Posted by Geomorph

Did you glue anything in between any of the three plywood layers?

The only thing between the plywood layers is some yellow wood glue, and not alot at that.

Is the vertical bulkhead at the front end of the boom from the same sheet of plywood the mount pieces came out of? If so I can pretty definitively say you got plywood that is too thick as you can see that it's likely 2x the thickness of my bulkhead from the second pics in both my posts.

I just love a good mystery!

I just dug up the plywood 'skeleton', and yes indeed the bulkhead and wing hold-down pieces came out of the same bit of plywood. I don't have an accurate ruler handy (just a yardstick) but it might be a little over 1/8". Also the tabs did not fit easily into the slots, which also points at slightly (but nowhere near 2x) thick ply.

If I remember I'll take the plywood skeleton to work tomorrow and see if I can get a better measure of it's thickness -- that might very well put this mystery to bed!

Movie night tonight (sadly the movie wasn't great, but the company was good) so further work on the Gambler will have to wait until tomorrow .

-Rick

Originally Posted by Geomorph

Right at 8.5mm thickness for just the plywood layers.

Curiouser and Curioser. My plywood appears to be pretty much right at 1/8". On the metric side it appears to be just shy of 3.5mm, this is with a ruler though rather than a caliper, though. Even at 3.3 that's more like 10mm thick for 3 layers vs the 8.5mm you measured on yours. Perhaps enough to explain the mystery?

-Rick

Possibly my most recent batch of 3mm plywood was a bit thick from the factory. Sand down to flush with the pod's balsa and you should be fine. I'll check my other kits.

Regarding the Kevlar stitching, I've also seen hard launchers reinforce the front sheeting at the dihedral break with more 0.75 oz fiberglass. I did this on one of my wings that I brought to contests and shows just for safety.

Thanks, Allan. My piece of plywood appears to be exactly 1/8" rather than 3mm.

I hate that the wood industry often sells plywood by "nominal" thickness... then substitutes the next smaller metric measurement (3mm instead of 1/8, 6mm instead of 1/4 etc). If it's metric wood, just label it metric!

I fear I have installed mine a little askew, so I'm thinking of just cutting out the old hold-down block and creating a new one, maybe CA-reinforced balsa with 4-40 a threaded insert?

-Rick

In this case I purchased 3mm European birch plywood. If it measured 1/8" that's why it's too thick. Strange.

Not sure what you mean by askew, but as long as it will hold the wing square to the boom, you're probably ok.

So I'm really new to the DLG scene in general, and I was looking this past month at getting a good entry level DLG that I can mess around with. I attended a nearby swap meet a couple weeks ago, and lo and behold there was a Gambler+ for sale! I knew that it would be perfect for my skill level, and it actually looked to be in very good condition, so I picked it up sans battery.

Once I got home, I realized that it was quite a bit tail heavy with a single cell 700mAh LiPo, so I had to add 3/4 oz of ballast, bringing the AUW to 7.7 oz. A bit heavy compared to a lot of the weights I've seen in the Gambler threads, but it flew fine during the test flights. Unfortunately, I fly in a cemetery, and I had the misfortune of javelin launching it into an unrecoverable turn downwind, straight into a headstone. The damage was actually somewhat less than I expected! There's a chunk taken out of the nose, the main fuse former is displaced, and the left LE is crunched near the peg, but nothing unfixable.

While I'm repairing the Gambler, I think I can move some of the gear forward so that I can take out some of the ballast. I may also do some work on the control linkages because the L-bend setup takes a lot of carbon rod length that could be used to move the servos forward. My main question is, how do I repair the nose block and not make it heavy and/or look terrible? I'm pretty new to balsa construction at this size, although I do have a lot of tools that I used to use for balsa free flight models. Thanks guys, really appreciate the help!


(Pics below to show the damage is no April Fool's joke! )

You could switch to string-spring controls and entirely get rid of those control rods. That would help your CG too. I was once suspicious of spring-string controls, but tried it and am convinced it's the way to go for rudder and elevator.

The nose block from F1 forward is a solid block of balsa that is just glued in and probably covered with fiberglass and epoxy, you could either cut that entire block off and rebuild or just use filler, sand to shape and redo the fiberglass and epoxy coating.

Ernie

Thanks for the tips guys! I should have posted an update here way earlier, but I just got to a point where I need your expertise again! I ended up getting the wing repaired and just left the nose as it was since it didn't seem to be affecting flight characteristics. The repairs have lasted for the duration of the summer, and I've gotten a few more good thermal and slope flights in. However, I recently broke the pod-boom glue joint on a hard launch (whoever built/repaired this area seems to have used polyurethane glue instead of epoxy or CA ) and I figured that I may as well remedy some of the issues I've been having by building a new pod and removing excess weight at the tail.

To this end, has anyone built a slimmer pod for their Gambler? Since I've also started building a MiMi 1m DLG, I was thinking about adapting the MiMi's pod design since it has a smaller frontal area and is a better fit for the small 5-gram servos and lipo I plan on using. I am also thinking about lengthening the MiMi pod design to avoid having to add excess noseweight, although this depends on whether I can get the tail section's weight to something reasonable. Originally the complete tail including boom, tail feathers, and pushrods was around 28 grams total. I've already gotten it down to 19 grams by removing nearly all of the carbon reinforcement, the pushrods + external guide tubes, and the rudder and elevator. The elevator alone somehow weighed 4 grams! I will be switching over to pull-spring as 2400RDR suggested as well. I'm guessing that the new finished tail section will be between 20 and 25 grams. Does anyone think is this a good weight or will I need to resort to a longer pod/more noseweight/shorter tail?

Looking at your photos, the primary reason your tail is heavy is the person who built yours put push rods on the outside of the boom with sleeves instead of just running the push rods inside the boom as the kit was designed. Pull-pull would resolve this. Be careful removing the push rod tubes (use acetone to dissolve the CA). You don't want to scratch/score the boom and create weak points.

As you can see the pod is a simple slab-sided affair (to keep it light). If you want to build a thinner one that would be fine, although remember any weight you take off the nose has to be matched 4:1 in the tail.

Originally Posted by Aer0naught

Thanks for the tips guys! I should have posted an update here way earlier, but I just got to a point where I need your expertise again! I ended up getting the wing repaired and just left the nose as it was since it didn't seem to be affecting flight characteristics. The repairs have lasted for the duration of the summer, and I've gotten a few more good thermal and slope flights in. However, I recently broke the pod-boom glue joint on a hard launch (whoever built/repaired this area seems to have used polyurethane glue instead of epoxy or CA ) and I figured that I may as well remedy some of the issues I've been having by building a new pod and removing excess weight at the tail.

To this end, has anyone built a slimmer pod for their Gambler? Since I've also started building a MiMi 1m DLG, I was thinking about adapting the MiMi's pod design since it has a smaller frontal area and is a better fit for the small 5-gram servos and lipo I plan on using. I am also thinking about lengthening the MiMi pod design to avoid having to add excess noseweight, although this depends on whether I can get the tail section's weight to something reasonable. Originally the complete tail including boom, tail feathers, and pushrods was around 28 grams total. I've already gotten it down to 19 grams by removing nearly all of the carbon reinforcement, the pushrods + external guide tubes, and the rudder and elevator. The elevator alone somehow weighed 4 grams! I will be switching over to pull-spring as 2400RDR suggested as well. I'm guessing that the new finished tail section will be between 20 and 25 grams. Does anyone think is this a good weight or will I need to resort to a longer pod/more noseweight/shorter tail?

FYI, I've been out of stock of kits for most of the summer. I've had some significant life events that have slowed down my hobby time. I have another partial batch on the work bench that should be ready later this fall.

Originally Posted by Allan Wright

Looking at your photos, the primary reason your tail is heavy is the person who built yours put push rods on the outside of the boom with sleeves instead of just running the push rods inside the boom as the kit was designed. Pull-pull would resolve this. Be careful removing the push rod tubes (use acetone to dissolve the CA). You don't want to scratch/score the boom and create weak points.

Yup, that's exactly what I've done so far! I don't know if I'll be saving too much because the pushrods were carbon and not music wire, but if I can end up removing even 5 grams from the tail I'll be more than pleased. One problem with pull-spring that I'm going to have is that the interior of the boom near the rudder seems to be blocked by some kind of repair job, which means that I would have to drill the hole for the rudder string in front of the LE of the rudder, probably under the elevator pylon. Would it be best to stagger the holes for the rudder and elevator strings to minimize stress risers, or does it not really matter?

Originally Posted by Allan Wright

As you can see the pod is a simple slab-sided affair (to keep it light). If you want to build a thinner one that would be fine, although remember any weight you take off the nose has to be matched 4:1 in the tail.

I think I've come to the same conclusion. When I actually compared the cross-section of the original Gambler pod to the MiMi pod, they seem to have pretty much the same exterior dimensions, nullifying my main rationale for trying the MiMi design. I will probably just stick to the original pod design, with perhaps a tiny reduction in width and/or height to fit my servos. No point changing what ain't broken!

Also, I just wanted to say, thanks for your input, Allan! It's so great to see a designer that continues to take the time to provide tips and manufacture kits many years after a plane's inception. My hat's off to you!

Originally Posted by Aer0naught

Would it be best to stagger the holes for the rudder and elevator strings to minimize stress risers, or does it not really matter?

yes, and maybe a wrap or two of kevlar thread fore and aft of each hole to prevent splitting. Be sparing with the CA there.

Originally Posted by Aer0naught

Also, I just wanted to say, thanks for your input, Allan! It's so great to see a designer that continues to take the time to provide tips and manufacture kits many years after a plane's inception. My hat's off to you!

Thanks! I'm just a guy in his basement with a laser. The only way in which I can ACTUALLY compete with the big manufacturers is to provide a better level of customer service and work in a product niche too small for them to be able to make a profit in and crush me. That's why my product line is so seemingly random.

FYI for those waiting on kits. While working on the next batch last night my laser blew up a stepper motor. Since the laser is 2003 vintage, it's going to take a bit for Epilog to come up with the replacement part. I think they might have to (gulp!) custom order it. I'm sure that won't be cheap.

Anyways another hiccup in the process. I'm working on it!

That sucks to hear. But this fine plane is worth the wait.