RE: Need CG confirmation

RE: Need CG confirmation
View related threads: (in this forum | in all forums)

Logged in as Guest

Users viewing this topic: none

Printable Version

All Forums >> RC Airplanes >> Giant Scale Aircraft - 3D & Aerobatic >> Quique's Aircraft Support >> RE: Need CG confirmation

Page: << < prev 1 [2] 3 next > >>

Login

Message

<< Older Topic Newer Topic >>

RE: Need CG confirmation - 6/14/2006 6:04:46 PM

Posts: 53
Joined: 6/30/2004
From: Houston, TX, USA
Status: offline

Hi Bart,

How are you checking your CG...I would really recommend use "vanesa".

John

(in reply to bart-rennes)

RE: Need CG confirmation - 6/14/2006 6:13:56 PM

Posts: 58
Joined: 5/17/2006
From: G�vez�, FRANCE
Status: offline

What is vanesa ?

(in reply to jdavera)

RE: Need CG confirmation - 6/14/2006 7:47:04 PM

Posts: 709
Joined: 9/15/2003
From: Gulf Breeze , FL, USA
Status: offline

this cg is a problem for me . I did my maiden flight yesterday. I had to put 8oz of lead on the engine box (back side of firewall). I already have all my batteries on the engine box . My cg was about 1/2" behind the rearmost recomended, the plane flew great. (only one 8 minute flight). Inverted I had to only push the slightest amount to keep level. I would not want it any more nose heavy as I like if my planes fly inverted with very little or no push. I think I will try to remove some lead and move the batteries to a plywood extention getting them foward of the engine box. also I am going to get a heavy spinner. that would let me remove more weight in lead than the spinner weighs as the spinner is way out front.

When someone asks about this plane we should always tell them not to spend lots of $$$$ on a CF spinner. I think almost everyone would agree that a heavyer spinner will in most cases be better. (better than lead for sure)

_____________________________

Ask me about
Pensacola FL - Pro Bro & Gaint Scale 3D, June 14 & 15 2008

(in reply to bart-rennes)

RE: Need CG confirmation - 6/14/2006 8:32:32 PM

Posts: 58
Joined: 5/17/2006
From: G�vez�, FRANCE
Status: offline

buildflycrash: What is your motor ? if DA50, could you take a look on the distance between your prop and your cowl ?

Rezagh: i was looking for different motor (without muffler) :
ZDZ50NG: weight = 1.42kg (3,13 lbs), length (motor box to prop on yak) = 166mm (5.61 oz)
DA50: weight = 1.33kg (2,94 lbs), length (motor box to prop on yak) = 163mm (5.51 oz)
3W50: weight = 2kg (4,45 lbs), length (motor box to prop on yak) = 169mm (5.71 oz)

So my conclusion is that i understand nothing ! it is recommended for DA50 which is less heavy than my motor (ZDZ) and prop is closer to cowl than my installation

even with all these motor, there is not the 37mm between prop and cowl !

... What's wrong with my plane ? wood is too heavy !!
I would like to avoid to add lead on motor box...

< Message edited by bart-rennes -- 6/14/2006 8:33:12 PM >

(in reply to buildflycrash)

RE: Need CG confirmation - 6/14/2006 8:49:50 PM

Rezagh

Posts: 1855
Joined: 6/10/2004
From: Rancho Santa Margarita, CA, USA
Status: offline

It is suprising with ZDZ 50. Are you balancing at 7 3/8" or 7 1/4"? Where are you balanced at right now? Can you tell me where your CG is located with your current set up. You are balancing with prop and spinner on the plane, right?

Honestly with the depicted picture and ZDZ 50NG you shouldn't have any problem unless you are trying to get it balanced nose heavy! What servos are you using for your elevator? What's the weight of those servos?

Thank you,
Reza

_____________________________

Quique's Aircraft Company

(in reply to bart-rennes)

RE: Need CG confirmation - 6/14/2006 11:46:34 PM

Posts: 53
Joined: 6/30/2004
From: Houston, TX, USA
Status: offline

Bart, check out the link for Vanessa...

http://www.rcuniverse.com/forum/m_708060/anchors_708060/mpage_1/key_vanessa/anchor/tm.htm#708060

John

(in reply to Rezagh)

RE: Need CG confirmation - 6/15/2006 8:25:40 AM

Posts: 58
Joined: 5/17/2006
From: G�vez�, FRANCE
Status: offline

I think i have a conversion problem. Can someone give the conversion of 7 3/8" in millimeter(mm) or centimeter(cm) ?
Me i found for 7 3/8" = 18,73 cm

For info my servos for elevators are TowerPro MG995, weight is 60gr (0.13 lb). Of course i'm balancing the CG with prop and spinner.

(in reply to Rezagh)

RE: Need CG confirmation - 6/15/2006 10:09:19 AM

Posts: 4370
Joined: 10/12/2005
From: Wychling, Kent, UNITED KINGDOM
Status: offline

Bart
25.4mm = 1" therefore 7 3/8" = 7.375" x 25.4 + 187.325mm you are spot on. Back of prop or spinner should be somewhere in the region of 1 1/2" in front of the cowl, this looks ugly but is neccesary to balance a lightweight engine, the Real Yak also has a large distance between the cowl and spinner so you can always say its scale.

Mike

< Message edited by BaldEagel -- 6/15/2006 12:02:49 PM >

_____________________________

No matter what anyone says 100% is the maximum you can get.

(in reply to bart-rennes)

RE: Need CG confirmation - 6/15/2006 7:37:31 PM

Posts: 58
Joined: 5/17/2006
From: G�vez�, FRANCE
Status: offline

With everything like on the picture (batteries over motor), i get CG at 18.3cm (7.20 inch)...
I will try tomorrow first flight, hope it will fly correctly

(in reply to BaldEagel)

RE: Need CG confirmation - 6/15/2006 7:41:47 PM

Rezagh

Posts: 1855
Joined: 6/10/2004
From: Rancho Santa Margarita, CA, USA
Status: offline

7.2 is OK. I have mine at 7.25" and it flies fine. Keep us posted.

Reza

_____________________________

Quique's Aircraft Company

(in reply to bart-rennes)

RE: Need CG confirmation - 6/15/2006 8:00:07 PM

Posts: 58
Joined: 5/17/2006
From: G�vez�, FRANCE
Status: offline

7.2 fine, you are a good pilot, me this is the first time i have a plane of this size

(in reply to Rezagh)

RE: Need CG confirmation - 6/15/2006 8:03:38 PM

Posts: 1281
Joined: 1/11/2005
From: Brentwood, TN, USA
Status: offline

quote:

ORIGINAL: bart-rennes

7.2 fine, you are a good pilot, me this is the first time i have a plane of this size

Mine started out at 7.25....I had a few ounces of weight up front. They started falling off and I didn't notice it until most of it was gone. It flew fine - even when I had lost almost all of the weight, the plane wasn't overly sensitive - the tail just squatted down in the air (looked a tad funny)

(in reply to bart-rennes)

RE: Need CG confirmation - 6/16/2006 5:53:52 PM

Posts: 58
Joined: 5/17/2006
From: G�vez�, FRANCE
Status: offline

it flew today with CG at 7.2, it fly well except it is really sensitive at elevator

So i've just advanced the motor and now i have exactly 37mm from prop to cowl, tomorrow i will test it.

For information, at first flight all blue cover on the wings fell apart (go away), i'm sad for covering quality. Anyway i have good feeling with this plane.

Thanks to all of you, in particular Reza, for your support.

(in reply to shakes268)

RE: Need CG confirmation - 6/16/2006 5:57:00 PM

Posts: 1281
Joined: 1/11/2005
From: Brentwood, TN, USA
Status: offline

Congratulations on your maiden! This was my first giant scale plane as well and I love how it flies - hope you enjoy it as much as I have. Sorry about your wing covering though

(in reply to bart-rennes)

RE: Need CG confirmation - 6/16/2006 6:41:53 PM

Posts: 4370
Joined: 10/12/2005
From: Wychling, Kent, UNITED KINGDOM
Status: offline

bart

Congratulations on your succesfull mainden, I am still awaiting my engine from Just Engines they do not seem to be in the country as yet, still I have just booked a week in Lozere in the Chateau de la Caze fly fishing that should take my mind off the engine especially as when I come back I go to Ireland Salmon fishing three days later.

Mike

_____________________________

No matter what anyone says 100% is the maximum you can get.

(in reply to bart-rennes)

RE: Need CG confirmation - 6/16/2006 7:35:43 PM

Rezagh

Posts: 1855
Joined: 6/10/2004
From: Rancho Santa Margarita, CA, USA
Status: offline

Bart,

I'm glad if I could be at any help which in your case would be little to none. I hope you enjoy the plane after some fine tuning. Now that you've flown it, you have a better idea of what to change.

Don't hesitate to ask any questions that you may have,
Reza
Quique's Aircraft Support

_____________________________

Quique's Aircraft Company

(in reply to bart-rennes)

RE: Need CG confirmation - 7/31/2006 7:52:44 PM

paully

Posts: 162
Joined: 1/4/2003
From: Coningsby, UNITED KINGDOM
Status: offline

hi all,
i am having difficulties as well with my cg
i have a da50 up front and i am using a 2400 c cell ignition pack which is strapped to the top of the engine box. the ignition unit is on the side of the engine box as well.

For the radio gear batteries, i am using 2 x 1500mah flightpower lipos through a smartfly super regulator aND THESE BATTERIES AND THE REG ARE UP FRONT UNDER THE top deck butted up against the firewall.
I measured the cg position as per the manual and it is WHEY too tail heavy.
I spoke with mike at Fusionmodels.co.uk and he told me that an 85" er that they test flew yesterday was the same.They added another batter (ballast) and it seemed to sort it out on the ground but in the air it became quite nose heavy.

What am i doing wrong here???

paul

_____________________________

Aint enough hours in the day for RC!!!!
Good job for WWW.micro-rc.co.uk

(in reply to Rezagh)