SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Oct 09, 2012, 01:33 AM
Young Poor and Fun
United States, TX, Austin
Joined Sep 2012
101 Posts
Build Log
The Cool Ghoul

After watching an episode of Flite Test on YouTube aptly named 'Cool Ghoul' we decided we just HAD to make this plane for Halloween.

The plane design is simple - a nutball.

The ingredients thus far;

(2) 30”x20” Foam Board
Chop, paint & popsicle Sticks
Gorilla & scotch packing tape
(4) $2 10g Servos
Turnigy Blue LED Light Strip - 1 Meter
1 Really Awesome Ghoul from the grocery store (the eyes light up and it screams).

Borrowed from one of our other planes:
HK 6 ch Radio/Receiver
HK Donkey ST3508-730kv Brushless Motor,
HK Blue series 30A Speed Control
350mah/2200mah/1000mah Batteries (whichever is charged)
Ingenuity
Flight test videos
$50

Flight test is always talking about “Dollar Tree foam-board” we don’t have dollar trees up here and had to pay 100% more. It actually took us a lot of hunting to figure out we weren’t going to get a larger size foam-board for under $15.

The best deal we got was on the servos - Hobby King for $2, you really can't beat that price. The LED's were great too, at less than $5 for a Meter!

We shopped around for a ghoul and finally settled on one we found at Fred Meyers that was on sale for $18.

All in all, we are well within our $50 budget, having only spent $36. Not too shabby!

The craziest part? We got the idea from flite Test, but there is NO plans or guidance on making these anywhere! We’re building it based on pausing the flight test video when a good angle of the plane is in view.

The build at this point has been split between the two of us with Paul making the nutball and me fixing the ghoul up to be a bit lighter and more frightening.

The ghoul was already pretty light with a 'mask' face comprised of foam and latex, cheesecloth material, wire arms with plastic skeleton hands, and an electronics box that allowed the eyes to light up, the crazy scary laughter, and vibration.

We decided the ghoul needed to be lighter so the hands had to go since they were heavy, solid plastic. I lightened it further by tossing the plastic electronics box in favor of a lighter Ziplock bag box and by removing the motor and motion ballast (we don't need the vibration). I added to the lightened ghoul a scary black hood and cloak which makes it look really freakin’ scary. The original white cheesecloth is used in place of the hands.


The Nutball was build using guess work almost exclusively. It all started with taping two of the foam board pieces together and then measuring a circle. Cutting notches and gluing to make the polyhedral, then more notches were made to fit in the profile 'quasi fuselage' aka 'long vert. stabilizer on the top. Finishing off with a motor mount and rigging servos with BBQ skewers.



So far this build was started yesterday and today we are nearly finished. We have painted the ghoul side of the foam board black leaving a 'splash' circle of white in the middle so we can do a lifted attachment and put the ghoul on it and the lights around to give it an extra glow.

Y.P.F. is offline Find More Posts by Y.P.F.
Last edited by Y.P.F.; Oct 10, 2012 at 06:59 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 10, 2012, 02:30 AM
Young Poor and Fun
United States, TX, Austin
Joined Sep 2012
101 Posts
Ghoul Update

Just a quick update - we got the backing on and added a bit of colour to the white section on the plane before we got the ghoul attached. We noticed the ghoul - while it is significantly lighter than it was, it's still heavier than the plane... Not necessarily a bad thing as the motor can take it. We'll find out when we test it out after we finish with the electronics.
Y.P.F. is offline Find More Posts by Y.P.F.
Last edited by Y.P.F.; Oct 10, 2012 at 04:59 PM.
Reply With Quote
Old Oct 10, 2012, 07:25 AM
Registered User
Schoolya's Avatar
United States, FL, Mayo
Joined Jul 2012
144 Posts
Interested to see if this will fly. I think the fact that you are eating up a lot of your "wing" with the ghoul will be more detrimental to you flying then the weight. If it does fly, it will fly pretty slow with all that drag from the cloth I imagine.
Schoolya is offline Find More Posts by Schoolya
Reply With Quote
Old Oct 10, 2012, 03:55 PM
Young Poor and Fun
United States, TX, Austin
Joined Sep 2012
101 Posts
Will It fly?

Quote:
Originally Posted by Schoolya View Post
Interested to see if this will fly. I think the fact that you are eating up a lot of your "wing" with the ghoul will be more detrimental to you flying then the weight. If it does fly, it will fly pretty slow with all that drag from the cloth I imagine.
Hey Schoolya,

Our fingers are crossed!
I don't know if it will fly, we'll find out soon enough though. The flight test cool ghoul had a 4" bigger nutball and a smaller ghoul so not being able to fly is a legitimate concern.
Tonight will be the maiden for the nutball; tomorrow we'll attempt the whole thing. The motor we're putting on it will be able to lift everything vertically so it should be able to flail before crashing a worst. The cup that's rigged to hold the lights and ghoul is suppost to move the ghoul off the wing surface; I'm not sure if the distance from the ghoul is enough. We'll try to post a video of our ghoul maiden so you can see if it really does or doesn't.
Y.P.F. is offline Find More Posts by Y.P.F.
Reply With Quote
Old Oct 12, 2012, 01:20 AM
Young Poor and Fun
United States, TX, Austin
Joined Sep 2012
101 Posts
The maiden flight wasn't all it could be. The elevons were huge with huge movements. The right elevon's push-rod fell off the servo and, well, you'll see what happened. I've almost got it fixed. Hopefully I'll have time to try again tomorrow. Maybe even with the ghoul.
Flight of the 30" Nutball (0 min 57 sec)
Y.P.F. is offline Find More Posts by Y.P.F.
Reply With Quote
Old Oct 12, 2012, 01:26 AM
Mister Fear
USA, NV, Las Vegas
Joined Nov 2010
246 Posts
I think you'd be better off hanging the ghoul under a quadrotor.
Mr Pheer is offline Find More Posts by Mr Pheer
Reply With Quote
Old Oct 13, 2012, 01:08 AM
Young Poor and Fun
United States, TX, Austin
Joined Sep 2012
101 Posts
We fixed the nutball, balanced it and got the control surface movement tuned up. Man it is a really stable flier at high angle of attack; I could fly it hands off. I flew it with the CG 25% back from the motor. Here's the beginning of me trimming it out. I was able to fly, hands-off later in that flight.

30" Nutball stability (1 min 12 sec)


All systems were go so we attached the ghoul. The motor has enough power to lift the whole thing vertically but I think the extra drag may have effected the . . . well, you'll have to watch the video to see what's up:

Cool Ghoul maiden flight (0 min 16 sec)


We're planning to move the CG backwards and try a different take-off strategy tomorrow.
Y.P.F. is offline Find More Posts by Y.P.F.
Last edited by Y.P.F.; Oct 13, 2012 at 02:03 AM.
Reply With Quote
Old Oct 13, 2012, 05:21 AM
DIY Mania from Taiwan
Taiwan
Joined Aug 2011
1,945 Posts
Nice try
just an idea.....
suggest to glue the Ghoul directly to the bottom of the Nutball and leave no space in between to get rid of the troublesome drag
have great RC gun
regards
Sam
samwei1950 is offline Find More Posts by samwei1950
Reply With Quote
Old Oct 13, 2012, 04:28 PM
Young Poor and Fun
United States, TX, Austin
Joined Sep 2012
101 Posts
The motor mount was fixed from the first flight, some minor damage to the foam board was repaired, the battery was moved back further, and the elevator was given full trim up to help hopefully level things out.

After all that was complete we decided to take the ghoul out for round 2... It didn't go exactly as planned.

The Cool Ghoul Take 2 (0 min 17 sec)
Y.P.F. is offline Find More Posts by Y.P.F.
Reply With Quote
Old Oct 13, 2012, 05:23 PM
Watts is life...
rcjetpilot's Avatar
Bot's like to know where you live
Joined Sep 2003
2,860 Posts
Dang.... it looked like #2 attempt was gonna work!

Thanks for posting the progress... trust me, everyone is watching and enjoying
rcjetpilot is offline Find More Posts by rcjetpilot
RCG Plus Member
Reply With Quote
Old Oct 15, 2012, 02:16 AM
Young Poor and Fun
United States, TX, Austin
Joined Sep 2012
101 Posts
Ever closer

Yesterday was a bust as it snowed all day. We built a third motor mount adjusted the elevons and balance and got this as a result:

Cool Ghoul "flight" #3 (0 min 27 sec)


This was due to a lack of power, we thought it was a weight issue and tried to get it moving enough for some lift by throwing it off some bleachers, it pitched up again and didn't crash too bad:

Ghoull flight #4 (0 min 10 sec)


That last crash didn't break it so I thought I'd give it a running start. It looks like I just threw it on the ground, we think it did the opposite of earlier because of the drag from the ghoul being at some speed:

Ghould flight #5 (0 min 18 sec)


In order to try and solve the power/weight issue we came home and took everything off the ghoul but the face, cut the spacer connecting the airplane and ghoul by more than half and tested the power from two different batteries. We were using a really light 350mah 65-130C battery with our motor which pulls 18 amps at max thrust according to its advertisement so we thought we were good. After connecting a 1,000mah 45-90C battery we realized the battery was keeping the motor from producing full thrust. We didn't really need to disassemble the ghoul but it's done. The control linkages made of bread ties and bbq skewers were pretty wobbly and unreliable as you can see with this flight.

Ghoul flight #6 (0 min 0 sec)


My girlfriend, with spectacular precision, snagged the ghoul from an imminent unplanned landing. We'll be getting real control linkages tomorrow and try again. Once we get things together, we'll add the lights, sound, arms and cloak back to the ghoul.
Y.P.F. is offline Find More Posts by Y.P.F.
Reply With Quote
Old Oct 15, 2012, 02:25 AM
Young Poor and Fun
United States, TX, Austin
Joined Sep 2012
101 Posts
Quote:
Originally Posted by samwei1950 View Post
Nice try
just an idea.....
suggest to glue the Ghoul directly to the bottom of the Nutball and leave no space in between to get rid of the troublesome drag
have great RC gun
regards
Sam
Sam,
I agree, although I think the ghoul would cover much of the lifting surface I agree that it seems to have a pendulum effect with the weight and the drag has a lot of leverage to pitch the nutball down. We've cut our plastic cup spacer down by over 50%. This has helped. Thanks for the advice!
Y.P.F. is offline Find More Posts by Y.P.F.
Reply With Quote
Old Oct 15, 2012, 04:29 AM
Mister Fear
USA, NV, Las Vegas
Joined Nov 2010
246 Posts
Third time's a try.
Mr Pheer is offline Find More Posts by Mr Pheer
Reply With Quote
Old Oct 16, 2012, 09:50 AM
Registered User
JohnsPop's Avatar
LaGrange, GA
Joined Jun 2009
1,813 Posts
Gotta hand it to ya for not giving up. Just looks (and even sounds) like you simply don't have enough power to drag that thing aloft. Getting closer though!
JohnsPop is offline Find More Posts by JohnsPop
Reply With Quote
Old Oct 16, 2012, 03:32 PM
Registered User
Joel K. Scholz's Avatar
Kingsland, Texas USA
Joined Aug 2000
2,406 Posts
With all the drag you have so low, I would think you would have to alter your thrustline to a steep upward angle. It is always going to be tricky as the faster you fly the higher the drag.
Joel K. Scholz is offline Find More Posts by Joel K. Scholz
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Careful! Hobby Cool (Not So Cool) tallflyer Vendor Talk 2 Nov 27, 2012 05:49 PM
Cool One Cool Dude. One Cool boat. LOL Will.E.King Dock Talk 0 Apr 18, 2012 12:14 AM
WHAT? not cool, not cool KingOfTheHill Slope 16 Apr 16, 2004 03:01 PM
How cool is Cool? I know why you like this guy. Doug @ MModels. genovia Parkflyers 20 May 24, 2003 08:19 PM