Some ancient astronaut theorists agree - Page 2 - RC Groups
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Nov 09, 2017, 10:05 AM
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I’ve done some searching on here and I’ve read that with a delta wing I need to have the cg at 40% from the nose of the aircraft. Would that work for this? Keep in mind that if you answer my question it may qualify you as an expert on the subject of ancient astronaut theory.
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Nov 09, 2017, 10:35 AM
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Quote:
Originally Posted by Dewey34
I’m not trying to say that the fish tail is wrong for flight im just saying that it doesn’t look like the one on the gold airplane.
Yeah foam & balsa fly much better than gold IMO
Quote:
Originally Posted by Dewey34
I’ve done some searching on here and I’ve read that with a delta wing I need to have the cg at 40% from the nose of the aircraft. Would that work for this? Keep in mind that if you answer my question it may qualify you as an expert on the subject of ancient astronaut theory.
The shown model looks like someone was inspired by flying fish as well as some birds and used that abstraction to make an object d'art. That doesn't preclude ancient folks playing with carved wooden models and getting them to fly somehow: as an undergrad I proved that a catapulted (loooong rubber!) plastic model plane would really fly at ca. 100 mph (one time/ model)

If that answer qualifies me as an expert, my expert assessment is that those ancient astronauts should be rightly ashamed of themselves for leaving humanity in the state its been in before and since and for thus allowing us to destroy this once reasonably well-functioning planet. Bad Boys! (stupid mean irresponsible aliens: why the "Prime Directive" is a worthwhile and valid concept)
Last edited by xlcrlee; Nov 09, 2017 at 10:46 AM.
Nov 09, 2017, 10:43 AM
AMA 537620
ChillPhatCat's Avatar
Quote:
Originally Posted by xlcrlee
Yeah foam & balsa fly much better than gold IMOThe shown model looks like someone was inspired by flying fish as well as some birds and used that abstraction to make an object d'art. That doesn't preclude ancient folks playing with carved wooden models and getting them to fly somehow: as an undergrad I proved that a catapulted (loooong rubber!) plastic model plane would really fly at ca. 100 mph (one time/ model)
Haha, I have also balanced a plastic model and made it fly... had to really throw it, but it worked and flew straight.
Nov 09, 2017, 02:40 PM
Registered User
While I’m very happy that you guys were able to balance your plastic airplanes I’m still wondering where the cg should be on this.
Nov 09, 2017, 02:46 PM
DFS#000178
Rampage's Avatar
You can make anything fly with enough power and the right CG.

Including a doghouse or lawn mower.
Nov 09, 2017, 03:06 PM
An itch?. Scratch build.
eflightray's Avatar
If you must, ..... make a small scale chuck glider model, could be a flat profile about 1/4 scale, and use that to find its CG.

Then just scale that location to the size you want to build.

It works, and is the easiest way to determine the CG on an unconventional shape.

Alternatively, try the flying wing CG calculator -- http://fwcg.3dzone.dk/
Nov 09, 2017, 03:23 PM
aka: A.Roger Wilfong
gnofliwr's Avatar
Back in the '50s, Monogram or Revell had a couple of flying plastic models. I'm talking regular injection molded plastic model kits. One was a jet. There was a small hole in the wing that accepted a string. You just whip flew it around in a circle. The landing gear permanently retracted (read broke off) on the first landing.

I flew mine in the street in front of our house. On the second flight a car came along (what was he thinking, driving down the street) so I had to move to the curb. Sure enough, the tree in the middle of our front lawn leaped out and center punched the plane. Outside of the wing attached to the string, there wasn't a piece big enough to recognize.

Oh well, I'd done a lousy job on the paint any way.

- Roger
Nov 09, 2017, 04:57 PM
Registered User
Thanks Ray
Nov 10, 2017, 11:35 AM
Suspended Account
You can fly it from these ancient runways and park it in the ancient dispersal bays.:



It looks like someone just did
Nov 10, 2017, 02:14 PM
An itch?. Scratch build.
eflightray's Avatar
It looks more like someone was mowing the club flying strip after a few too many cans.

.
Nov 10, 2017, 09:04 PM
Registered User
I’ve always wanted to go to Peru and see the Nazca lines.
Nov 12, 2017, 07:51 PM
Registered User
I built this little glider to find the right cg. I started out with a 20 triangle but then I rounded the tips on the trailing edge. The span is now about 18.5 and the cord is 18 even. I had to put the cg 10.5 from the nose to get it to glide right. I ran the numbers and I figured it should be about 8.5. Why would it be so far off? Aliens???
Nov 12, 2017, 07:55 PM
Registered User
Quote:
Originally Posted by Dewey34
I built this little glider to find the right cg. I started out with a 20” triangle but then I rounded the tips on the trailing edge. The span is now about 18.5 and the cord is 18 even. I had to put the cg 10.5” from the nose to get it to glide right. I ran the numbers and I figured it should be about 8.5”. Why would it be so far off? Aliens???
Because you "ran numbers" on a theoretical or math model that did not correctly model reality, likely based on incorrect or grossly simplifying assumptions
Nov 13, 2017, 07:07 AM
Registered User
Actually I used the calculator that eflightray linked.
Nov 13, 2017, 09:07 AM
An itch?. Scratch build.
eflightray's Avatar
Don't forget you will probably need a little reflex at the trailing edge of that shape.

Deltas, and most other models without a horizontal stab, need the trailing edge raised slightly to give some pitch stability. Probably an 1/8" up at the trailing edge over the last 1/2" to an 1" of chord.

As you also have no dihedral, as a chuck glider it wont be very stable laterally.


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