Thread Tools
Apr 23, 2015, 10:02 AM
Registered User
John Xman's Avatar

OH My Back


Ah to be young again! See the guy on the G4 drop on the mast. I bet he hurts today!
This is why I am building a 86" cat so I can have all the excitement and none of the pain!

John Xman

PS-- are any of you foil builders doing asymmetrical foils? When I looked at Oracle 72 and 45 foils the bottom of the tip was quite flat allot more curve on the top. Same with the vertical section- Designed for higher lift to the windward or inside face. Or are you just sanding so the two sides match?
Sign up now
to remove ads between posts
Apr 23, 2015, 10:15 AM
Registered User
DLord's Avatar

Foils


My Fire Arrow UptiP ama foils are all asymmetrical as are the D4Z lifting foils. The FA ama foils have a three degree twist to the "uptip" portion of the foil as well as an intrinsic 15 degree flap. The reason is to prevent having to manually(by servo) adjust the AOI for takeoff and cruise. This way is 100% automatic-and it works.
They're loosely based on a 63412 foil but reduced to 9-10%.
Last edited by DLord; Apr 23, 2015 at 11:14 AM.
Apr 24, 2015, 04:51 PM
Registered User
DLord's Avatar

D4Z-- AC 4.8RC Foiling Cat


Got everything wired up and programmed, ready to install:

click-
Last edited by DLord; Apr 29, 2015 at 03:09 PM.
Apr 24, 2015, 11:42 PM
Registered User
Quote:
Originally Posted by DLord
Got everything wired up and programmed, ready to install:

click-
Sure Wish i could Be There ; for the Test sail !!!!!!!!!

Ya gonna take a bunch of video ?

And DLord ; thanks a , ("Lot") for the time you took, explaining the
GunBoat foil !!!!

Bille
Apr 25, 2015, 07:48 AM
Registered User
DLord's Avatar

D4Z-- AC 4.8RC Foiling Cat


You're welcome! Lots of video coming....
Last edited by DLord; Apr 29, 2015 at 03:09 PM.
Apr 27, 2015, 08:11 AM
Registered User

AC 4.8RC Boat 2 - Wing sail


My availability for sailing, and suitable wind haven't coincided particularly well recently. I managed one session, but when the wind arrived it was accompanied by rain (and the batteries on my video camera running out - hence the stills):

AC 4.8RC - Boat 2 - Wing Sail 2 (2 min 43 sec)


I'm not happy with the wing in its current form. I need to cut the chord of the front element, and I think that I will use a semi-soft flap, or perhaps, soft and seems-soft (and yes Billy, increase the height).

With the wing in its current form and the test conditions it was a bit hard to draw any conclusions regarding the foils.
Last edited by rcmm; Apr 27, 2015 at 08:24 AM.
Apr 27, 2015, 10:25 AM
Registered User
Quote:
Originally Posted by rcmm
My availability for sailing, and suitable wind haven't coincided particularly well recently.
...

I'm not happy with the wing in its current form. I need to cut the chord of the front element, and I
think that I will use a semi-soft flap, or perhaps, soft and seems-soft (and yes Billy, increase the height).

...
May i suggest that you don't modify anything , until you do get
suitable wind ? And even in decent wind ; there is a learning curve
that needs to be addressed.

On the main wing : look at the photo of my Rigid wing .
Changing the flap
setting , makes a Huge difference in the way the pitching-moment for
different AOA is affected ; I compensate by changing my CG in flight, with
just a slight tug on my control-bar , (a LOT of tugs) . That's why i mentioned
the thing about the learning curve ! Every slight change in flap setting, will also
change the C/L of the main wing , (change it a LOT).

Personally i think your better-off with the rigid flap ; it is much easier
to control the Coefficient of Lift, with a rigid one. I fly both Rigid
and soft wing hang gliders ; a bent batten on the soft wing will make
big differences in the way the wing preforms.

My Rigid-wing uses spoilers to turn , and i have flap settings from 0 to 45-deg
down.

Wing height ; wouldn't it be cool to have telemetry , with airspeed
given at 1/3 up the mast , and at the top ? Then you would know if
there is a wind gradient affecting your performance !

Wings i know about ; hydrofoils are a different story, and
i need help .

Bille
Last edited by BilleFly; Apr 27, 2015 at 10:30 AM.
Apr 27, 2015, 10:57 AM
Registered User
Thanks for the suggestions Billy. I actually got a bit of decent wind, enough to draw a few conclusions. Unfortunately, the wind arrived with rain, and my batteries ran out, so no video. I think that I got the main element chord length and the aspect ratio of the wing all wrong. Consequently it was a bit top heavy and didn't produce a suitable airfoil profile, or any twist. I'm planning to reduce the chord of the front element significantly, keep the flap, and add a soft, or semi soft section.The control will work as shown in the attached image:
Apr 27, 2015, 11:51 AM
Registered User
Don't you ever sleep? lol
Apr 27, 2015, 12:01 PM
Registered User
DLord's Avatar

Ac4.8rc


Thanks for the update, Jim! Already looking forward to the next one....
Apr 27, 2015, 01:29 PM
Registered User
Quote:
Originally Posted by rcmm
...
Consequently it was a bit top heavy and didn't produce a suitable airfoil profile, or any twist.
...
Another way to get that twist ; would be to cut off the top 1/3 of your
wing, and place a brass tube in it , and then splice the two wing sections back
together with a carbon rod. That would effectively turn the top 1/3 of
your wing into a wingaron , that it's AOA could be trimmed with a servo.

I guess the same could be done using two flap sections ; induce more
flap in the lower section of the wing ?

Bille
Apr 27, 2015, 02:26 PM
Registered User
John Xman's Avatar

Wings


Gentlemen,
In the videos I see almost no space between the front section and the rear flaps. AC Wings have a slot that is adjustable. I think your wing could benefit from a larger slot and bigger rear flaps. Almost all the modern wing designs have larger rear flaps the the front "Element 1" About a 60rear/40front% split typically. Wings are a low speed lifting surface, don't be afraid to widen out the front section. It's operating a a very low speed compared to any aircraft.
Before you do anything add some small telltales over the wing and watch how they flow. If you get any that stall out or flop around you have lost laminar flow over the wing- ie. wing is stalling. You want all the telltales flowing straight out.
I have attached a PDF from my AC-86 wing design showing the proportinons for front to rear size and the "Slot"
For what it's worth------

John Xman
Apr 27, 2015, 03:37 PM
Registered User
DLord's Avatar

wing


John,(and Bille)-- I've often thought about this and was wondering what you think: I could make a plug and mold for the forward and aft sections of a wing. The wing would be laid up with something like 3oz carbon. There would be a carbon tube added into the forward section(and maybe into the aft section as well) when the two halfs are glued together. A few foam stiffeners would be added during the bonding process. All this would occur right after layup. I did many hulls like this bonding them together as part of the layup.
What do you think of the basic idea? IF this could be done, the labor saving in building would be tremendous. Is 2.5lb too heavy compared to your method of building?

12.67 sq. ft area of one side
6.75' span
19" foot, 17" mid chord, 10" head
estimated weight including carbon tubes=2.5lb, 2 layers 3 oz carbon minimal interior structure.
Last edited by DLord; Apr 27, 2015 at 06:38 PM.
Apr 27, 2015, 04:21 PM
Registered User
DLord's Avatar

Foils-"lost" pix


I just found these pictures of the Fire Arrow ama UptiP foils. I figured they might help anyone contemplating an uptip foil since we know these work:
Apr 27, 2015, 06:37 PM
Registered User
John Xman's Avatar

Ac-48


Doug,
I have thought allot about the wing build for this size based on my AC-86 Wing.
The leading edge for both Element 1 and rear flaps Elements 2 would be a "D" shape Carbon Fiber Tube. You would then cut slots into the back flat part of the tube and insert thin plywood ribs for the pivot ribs at 12" vertically, all other ribs 4" vertically would be balsa. No reason for any internal tube. I think the wing would be more like 3 1/2 lbs.

John Xman


Thread Tools