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Pumpkin drop event

Giant Scale YB-35

#1
Ok so here is the build thread for my giant scale YB-35.

So far I've gotten most of the materials together and the plans printed out. First I plan to build a smaller scale version around 1/32 to test the airfoils, balance and control systems. The larger scale version will be 1/18 scale (around 114in span) and hopefully super scale.
 

wilmracer

I build things that fly (sometimes)
Mentor
#3
Very cool. I'll be watching (and hopefully see it in person at some point since you're so close by)
 

wilmracer

I build things that fly (sometimes)
Mentor
#5
Yea for sure sure Wilmracer, we'll have to get together for the test flight :)
Definitely. I'd be happy to have you out as a guest at one of the NVRC locations if you need a clear spot for something that large. The county just cleared about 10 acres on the north side of the field so the approach from the right is looking MUCH better than it did when you were out there for MultiGP. We may actually be able to use that area for some FPV racing in the future, but in any case we're getting more and more friendly for BIG stuff. They are out there today doing a controlled burn too. More happy airspace :)
 

VTX

New member
#6
This is gonna be goooooood.... How much functionality are you going to put into it? Moving landing gears? Bomb bay doors? I'm really excited to see this!
 
#8
Awesome Wilmracer I cant wait to get out there again!

All the functionality VTX!

I was thinking four emax gt2215 motors Shiitake

So it begins...
designing the wing scaffold for the test build.

KIMG1823.jpg
 
#9
So apparently building a floating build scaffold to build in the leading edge to trailing edge and wing root to wing tip taper and wing sweep all at once is a wee to complex.

Its all kinds of crooked
KIMG1824.jpg
 

Craftydan

Hostage Taker of Quads
Staff member
Moderator
Mentor
#10
I'd say "the table is your friend", but airfoils with a bit of belly on the bottom tend to be unfriendly.

True philosophically and in the real world, however -- the farther you get away from the standard of truth, the more warped the results become. In this case, your standard is your "flat" table top, and your scaffolding has you running away from your standard.

If your main spar were laid directly on the table (wax paper layer between it and the plans, naturally) and the rear stringer were blocked up with a stock wood strip just high enough to pull the foil's curve off the table and enforce the wash-in you like, it wouldn't be that hard to get everything true to the table. Always seek to get flat things pressed flat against something flat when gluing them in place.

Now how true your table is . . . that's another matter entirely . . . but I doubt that's your headache. Can't see anything "off" about your table from the pic you've shown, but few surfaces are truly flat. In most cases, however, the machinists are the only ones who'd care that it wouldn't be "flat enough".


In the end, most builders use the covering to set the final warp (or lack there of) on their wings, so by this point, close still counts . . . assuming you're still close enough.
 
#11
Thanks for the advice Dan, my table is a stainless steel box style table so its super true and flat :). I thought about blocking it up like that but the issue there is I cant get the taper and dihedral quite right. So I opted to divide the wing into top and bottom and just clam shell them together leaving the center rib off and then propping the whole thing up and gluing the center rib on after that to get the proper dihedral once the right wing is done. That way I can pin the rib halves down and they'll be nice and perpendicular to my table and I can insure nothing moves as I put more pieces on. After that I repeat the process with the left wing and mate it to the right and hey presto YB-35!
 
#13
Ok so a quick update here. Thus far I have a small portion of the right wing done (pictures to come) but I've been putting my efforts into the landing gear design and flight control systems. Being a glutton for punishment I'm going to stabilize it with a Naze32 and I have to write the code to make it do what I want... yay coding...
 

rspeed

An Ambitious Boxcar Hobo
#15
Finally something that got me excited enough to create an account!

By any chance will you be fitting either version with contra-rotating propellers?
 
#16
To be honest Rspeed I would love to, but it would be super complex to do so, so the answer is no. But if I manage to get it done in time for Flite Fest east I'll have a few surprises on it I'm sure everyone will get a kick out of ;)
 
#18
OK so I am alive. So far I've done everything on this project but build it, literally all thats left to do is the structure. I am aware of the time between now and FF and thats not an issue. The issue now is motivation, I just cant seem to get motivated to do the rest of the work on this beast. Does anyone have any advise?
 
#20
OK so I am alive. So far I've done everything on this project but build it, literally all thats left to do is the structure. I am aware of the time between now and FF and thats not an issue. The issue now is motivation, I just cant seem to get motivated to do the rest of the work on this beast. Does anyone have any advise?


Yep...sit down and start :)

It is hard when the motivation is lacking but it will come the more you persist at it !