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-   -   a couple printed ideas (https://vansairforce.net/community/showthread.php?t=147771)

Steve Melton 06-15-2018 02:14 PM

proto3 fuel cap cover
 
added contour adjustment features to the model. changed to a more compliant seal.






Steve Melton 06-16-2018 08:32 AM

will also evaluate this soft seal.




Steve Melton 06-16-2018 09:11 PM

fuel vent cover - slip on
 
reduced to two blades






Steve Melton 06-17-2018 08:58 AM

RV10 PC680 battery tray
 
kicking around a PC680 battery tray

the floor of this tray is raised .020 to ensure no contact on the radius edges.










a nice print


Steve Melton 06-17-2018 05:30 PM

fuel cap cover - water and wind speed test
 
water test was good. wind speed test, fuel cap cover departed at 35 kts on the runway. I am using grade 50 magnets but the fuel cap stem is stainless so not much mag force, but enough to make a good seal. need to find a way to withstand at least 70 kts. I have an idea how to do this.




fuel cap is dry



on route to high speed taxi


Steve Melton 06-18-2018 05:16 PM

fuel cap cover magnet with hook
 
the RV9 prototype fuel cap cover with magnet only departed the wing at 35 kts on the takeoff roll. the vibration from the takeoff roll could have contributed to the separation. so perhaps it could stay attached at a higher speed if vibration was not present. it's a slim clean design that only weights 21 grams.

the next prototype will include a hook that slips in the space just fwd of the latch. perhaps with both the magnet and hook I can reach the goal of 70 kts.


Steve Melton 06-18-2018 09:46 PM

RV9 fuel cap cover
 
further testing is promising. I found that orienting the gap in the seal to the side adds 10 kts to the separation speed for the non-hook variation. that's another 10 kts delta for separation at 45 kts. it is becoming my favorite because is it so simple and easily stored in the baggage area. the hook version separated at 48 kts but the hook was not optimized. will repeat the test with an optimized hook to achieve the goal of 70 kts. In a weird way I like calling the FBO and notifying that I lost a couple airplane parts on the runway and then scooting by on my Honda CB125 to retrieve them from the runway with the corporate pilots standing in the FBO, looking and shaking their heads.


the blow down test


gap in seal oriented fwd contributed to separation at 35 kts. notch is fwd.



gap in seal oriented to the side added 10 kts to separation (45 kts)



gap with hook with seal oriented to the side separated at 48 kts. the hook was not optimized so this can be better. I'm impressed with the ease of fitting the hook fuel cap cover. I am confident I can reach 70 kts.


a possible storage location. tape on magnet is temporary since I am prototyping.



the test vehicle

David Paule 06-19-2018 09:10 AM

For the folks who have an ADAHRS or magnetometer in the middle of the tailcone somewhere, will this affect their compass calibration?

I'd be concerned that if there was any effect, it would vary day to day as pilots moved these things around the aircraft for storage. In my opinion, magnets in an airplane that aren't permanently fixed in place, might become an unexpected hazard.

Could the magnets be attached to the fuel cap rather than the cover?

Dave

Steve Melton 06-19-2018 11:12 AM

Quote:

Originally Posted by David Paule (Post 1267828)
For the folks who have an ADAHRS or magnetometer in the middle of the tailcone somewhere, will this affect their compass calibration?

I'd be concerned that if there was any effect, it would vary day to day as pilots moved these things around the aircraft for storage. In my opinion, magnets in an airplane that aren't permanently fixed in place, might become an unexpected hazard.

Could the magnets be attached to the fuel cap rather than the cover?

Dave

At this time, I don't know how I could do that. Maybe something will turn up.

My magnetometer is under the aft fairing about six feet away. So it should be OK. My whiskey compass is about four feet forward. It could be affected.

Steve Melton 06-20-2018 09:24 PM

for me, the magnetometer is located six feet aft of the baggage bulkhead and the whiskey compass is located five feet forward of the baggage bulkhead. it couldn't detect any magnetic interference on a short test flight.

I reduced the edge profile to the seal with no hook as much as possible to decrease the area outside the seal to minimize the lifting area. I was able to gain 5 kts in separation speed with this change for separation at 50 kts. This is becoming my favorite configuration because it is simple and clean. I believe this is getting close to being offered to Amanda for her website. She calculated about $25 for a pair. The nice thing about these is that if the seal becomes degraded for any reason it can easily be replaced for low cost. The seal material is high grade, inner closed cell, solid outer shell, and I expect long life. Part weight = 21 grams each. Weight for a pair = 42 grams.




The fuel cover with what I thought would be an optimized hook separated at 45 kts. this was a disappointment. it did not have the reduced outer profile but I expected the hook to provide some benefit. my next iteration with the hook will be to add an angle to ensure the hook contacts at the bottom firstly. more to come on this. still attempting to get to 70 kts.




a version for RV7 and 8 is also in the works.




RV9 version



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