Let see if I can rebuilt the thoughts I had for post #299.
Now if I was to design this I would have had a carry through spar (structure) from the very beginning. Time and time again you and I have seen where the wings will crush the fuselage. In the early production runs we had seen where the bulkhead had popped just moving around the model in our hands. You asked for some glass structure over the bulkhead to encapsulate the bulkhead. The second run had a very thin web added (left uncut). This web was so thin that it was easy for it to flex (straighten) again allowing the bulkhead to pop. I think you then asked that the area where the canopy cut out would normally occur be left intact and have the same weight as the rest of the fuselage. This is what we have now. I have said this is a move in the right direction. As when I now flex the wing the wings actually flex rather than the fuselage distorting popping the bulkhead.
It appears that TJIRC is very receptive to the customers request. This is good, but the end product needs to be looked at as a whole. How does the change effect the whole? I don’t think TJIRC did this. The structure had a flaw they did make an attempt to correct the flaw at your request.
Now what should have been done, is that the TJIRC should have looked to see if the new structure that the customer (you) requested had any effect on existing structure. It did, I’m showing where the extended web is keeping the canopy from seating properly as the web interferes with the canopy hold down pins. The hold down pins are mounted to the canopy far enough away from the leading and trailing edge to allow the pins to flex over the lip of the canopy opening.
This need for pin flex is why the pins are so long. One can reduce the need for so much flex by putting the pins on a 0.25 mm to 0.50mm offset (shim) when glueing them to the canopy. This would allow the pins to be mounted closer to the canopy lip. Resulting in less of the fuselage web needing to be removed for the pin clearance.
Like I said I'd try to make a rigid carry through structure tying the spars together. To flatten the canopy area to make this feature would require adding material to the molds. I assume this is off the table as it would be too expensive to retool. So rather than having the end customer remove much of the newly added web. I’d take the material that is currently used to make the canopy area web and concentrate it over the bulkhead in a band that is about 20mm wide and about 6 times thicker. Have this thick rigid arch’s anchors spread over the area where the spars will be added. This modification would not need any changes to the molds. It should take as much material (weight) as we now use in the full coverage web. It would still allow for the as is canopy pins. There would need to be an adjustment made to the bulkhead laser cut file. While making that adjustment I'd remove the center hole in the bulkhead. (Maybe leave a small hole for the ESC wire to come back to the RX).
Now I wish I was as good a pilot to be concerned with the canopy scratching the fuselage. I’m still trying to keep the tips and nose looking something like they did when I unboxed the model.
I agree friction fittings and magnets don’t work! Now I come from the time in the 80’s when we got our models from firms like Graupner, Robbe, Simprop, FVK etc. These firms placed a high value on form follows function. On all but their entry level (throw away) models they used a positive spring loaded canopy retention pin. I’m sure these cost pennies Maybe even less than dual slide over flex pin, when looked at the whole manufacturing process. We really shouldn’t have to tolerated that side over pin.
Yes, as this is step up from the Alula I want bottom hinged control surfaces, both for performance and durability concern.
No, I haven’t asked for a new airfoil (this would drive whole new set of molds).
As it is now warts and all the "mini Q" at $160 is a far better value than the $90 EPO foam Alula.
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But I see where I think there is room for improvement at no added unit cost. (Yes, there might be some engineering costs, cut files and the like).
We will see what I can do with this as manufactured ship.
Now aren’t you sorry you asked.
-Konrad
