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Old Jul 02, 2014, 08:58 AM
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96" Canada Themed Flying Wing Build

Accelerated build video for my new "Canada Day" 8 foot KFm-2 Flying Wing

FPV96 - Giant Flying Wing Build (14 min 42 sec)
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Old Jul 02, 2014, 10:02 AM
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Great instructional video and very entertaining at high speed
I noticed you put in lots of spars - that is something beginners should pay special attention to.
Do you have specs and a flight video?
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Old Jul 02, 2014, 11:07 AM
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Great instructional video and very entertaining at high speed
I noticed you put in lots of spars - that is something beginners should pay special attention to.
Do you have specs and a flight video?
Thanks

I put spars in all of my wings. I don't know how sturdy they are without them, but I have had some nasty crashes and for the most part the wings themselves have survived (winglets break, but the wing survives) even if it's just to give the wing a little more stiffness I would do the same. Not sure I would recommend an 8 foot wing for a beginner though.

I don't have a maiden flight yet, it was too windy yesterday. Once it has successfully flown I will put in full dimensions and parts list.
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Old Jul 02, 2014, 11:13 AM
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Originally Posted by nuteman View Post
Great instructional video and very entertaining at high speed
I noticed you put in lots of spars - that is something beginners should pay special attention to.
Do you have specs and a flight video?
If you're interested before I maiden it, there is a link in the video description (on youtube) to the CG calculator for this wing. That link will show root chord, tip chord and sweep.
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Old Jul 02, 2014, 12:32 PM
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Thanks

I put spars in all of my wings. I don't know how sturdy they are without them, but I have had some nasty crashes and for the most part the wings themselves have survived (winglets break, but the wing survives) even if it's just to give the wing a little more stiffness I would do the same. Not sure I would recommend an 8 foot wing for a beginner though.

I don't have a maiden flight yet, it was too windy yesterday. Once it has successfully flown I will put in full dimensions and parts list.
I was just pointing out that beginners should not skimp on proper spars, regardless of size - and your video shows ample spars.

I've done several scratch built wings already, but I think it's very useful for all to see technical specs of successful designs - so that a "feel" for what works gels.

The constant chord, swept wing below is an example of one I did.
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Old Jul 02, 2014, 12:52 PM
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I was just pointing out that beginners should not skimp on proper spars, regardless of size - and your video shows ample spars.

I've done several scratch built wings already, but I think it's very useful for all to see technical specs of successful designs - so that a "feel" for what works gels.

The constant chord, swept wing below is an example of one I did.
I like that wing, haven't done a constant chord yet, but I'll put it on my list.

Yep, the stronger (and for the most part stiffer) the better.
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Old Jul 05, 2014, 02:05 PM
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Watched the whole vid and was great.
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Old Jul 07, 2014, 08:22 AM
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Maiden flight got close, but still some work to do.

Big Flying Wing Maiden Flight (6 min 3 sec)


I've since fixed the bad servo and ordered a larger prop. If I was doing this build again I would:

1) use 1" foam instead of 1.5" (would give a much better thrust to weight ratio)
2) use better quality servos and maybe thinner control surfaces.
3) either do two motors or a slightly larger motor (using the thinner foam might mean this would be unnecessary).

Still, I can't judge very well given that one of the four servos was dead. I'll wait until I have another flight with all systems checking out before drawing final conclusions.
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Old Jul 08, 2014, 01:06 AM
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So what are the numbers for your wing loading and thrust to weight ratio?
If your wing loading is reasonable then increasing thrust will do the trick.
But if the wing loading is unreasonably high to begin with, you might consider simply removing the top step. Having too much kinetic energy on landing is really just not worth the risk.
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Old Jul 08, 2014, 10:56 AM
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So what are the numbers for your wing loading and thrust to weight ratio?
If your wing loading is reasonable then increasing thrust will do the trick.
But if the wing loading is unreasonably high to begin with, you might consider simply removing the top step. Having too much kinetic energy on landing is really just not worth the risk.
Thanks for the tips.

I don't have real world numbers for wing loading, but this is my 9th wing build (all similar designs, but different sizes and materials). This does not behave like my most heavily loaded wings do (my fast FPV30 wing flies as if it is much heavier than this one). That said, if I needed to remove weight removing the top step would not be my first option. I would go the thinner foam route. The way this one is built, removing the top step would make my spar system much less stable as the spars come up to the surface level of the lower step. If I did remove the top step I would need to replace it with something to hold the spars in place.

It is possible that this will fly properly by just repairing the dead servo and not adding thrust at all, but a slightly larger prop is only a couple of bucks and the power system should handle it on a 3s.

Point well taken on kinetic energy on landing, but I don't think that will be an issue in this case. From the way it was flying I think it will glide in nicely at (relatively) low speed (assuming I have all four control surfaces on landing), also the park I fly at has a nice long flat area to land, so even if I had a failure on each side I should be able to bring it in. I could probably simulate this in my transmitter by using switch position to adjust the mix of the outer two elevon surfaces.

Additionally, I had put some extra weight in the nose thinking that this would be tail heavy. It did not fly tail heavy and on launch almost seemed a bit nose heavy, so I will remove that weight as well for the next attempt.
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Old Jul 08, 2014, 01:07 PM
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Cool.
Looking forward to the next flight vid, while I sip my beer
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Old Jul 08, 2014, 03:03 PM
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Cool.
Looking forward to the next flight vid, while I sip my beer
Calling for rain this weekend :-( I would have tried last night, but I had no volunteers to help with the launch...so I flew my little 30" wing instead. Still had a lot of fun and a pretty good crash too. The crash does illustrate your point about a good spar system :-) The crash is shown once at the beginning from the onboard camera and then again just over 6 minutes in.

FPV30 KFm-2 Cool Crash - Tough RC Plane (9 min 40 sec)
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Old Jul 08, 2014, 04:02 PM
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BeerNWingz,

Nice job on the large wing and good luck with subsequent flights. I built an 80" or so wing awhile back and it flew well. Seeing yours I now am inspired to have another go.

Paul
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Old Jul 12, 2014, 06:18 AM
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It flies, it actually flies!

Giant Flying Wing - Actually Flying! (3 min 25 sec)


Removed weight from the nose (mistake)
Fixed Servo
Used 4s instead of 3s

... and it flies!
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