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Feb 19, 2015, 02:49 PM
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Discussion

Fireblade DLG from GCM


Hello everyone,

It's my first post on RCgroups (biggest forum I’ve ever seen), so if I do something wrong, please let me know.

I'd like to present you a new DLG from my workshop which soon will be available to order. Wing is 100% G_T‘s design, thank you Gerald! We designed the boom and stabilizers. The prototype works great, a lot of work went into it . The main goals were to improve the launch, stiffen up boom, reduce inertia, and to make pretty big fin with G_T airfoil. Thanks to all these things model launch is much more stable and predictable, I think that this plane, with a good pilot, can easily do 80m. Sink rate is satisfying, air penetration and stability in turbulent air is much better than we expected.

Average weight of the plane is about 260g RTF, that means full spread tow carbon fiber skin, 29 g/m^2 biaxial carbon tails and 2,4GHz friendly fuselage.

Our next goal is to create a new model based on G_T EDGE wing. It will be focused on flying as long as it‘s possible in dead air and catching every possible thermal. High wing area with low weight (22dm^2, <250g). Apart from that we are starting a completely different project: SZD-56 Diana II with 5m wingspan, (I’ll post more about it in another topic)

I hope that photos will tell you more. You can find more details on our website www.GCM-model.com. I will try to keep it updated and also post all news in this topic.

Thank you for your attention, I hope you'll like it!

Sorry for my English! It's not my national language :-)

PS: more photos tomorrow.
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Feb 19, 2015, 03:21 PM
Registered User
very nice!!!!
Feb 19, 2015, 03:24 PM
Aurora Builder
Looks good! Which wing airfoil was used??

Update: It's unmodified ZV2 wing..waiting for those 80m altimeter logs if that is the case...
Feb 19, 2015, 03:26 PM
Registered User
How are you reducing inertia and yaw excursion with such a long nose?

-Robin
Feb 19, 2015, 03:53 PM
G_T
G_T
Registered User
Just a general FYI, the moment of inertia has a squared term for the distance from the center of mass. The tails and the ends of the wings are farther away and therefore have a lot more effect. To see an example of the contribution of distributed wing mass to yaw moment of inertia one can check out one of the ~recent spreadsheets I provided in the Synergy-II thread. One can quickly find out that, for instance, removal of a gram from the throwing blade install gives similar benefit to completely eliminating servos in the wing. Of course for the latter, they then have to go in the fuselage... at about the same distance or even farther from the CM. Different subject though. Anyway, comparisons on yaw moment of inertia for wing tips or tails (similar distances from CM) vs nose show it is about 10:1 more efficient to reduce mass at extremities and forget about optimizing the forward pod for moments of inertia.

Forward pod design has other effects though, beyond moments of inertia.

Gerald
Feb 20, 2015, 12:01 AM
G_T
G_T
Registered User
I forgot to mention - Welcome to RCGroups GCM_models!

Gerald
Feb 20, 2015, 05:50 AM
Registered User
Thread OP
Thank you Gerald!

Just like Gerald said:
Quote:
the moment of inertia has a squared term for the distance from the center of mass
The equipment is now closer to the CM, boom is shorter than before. Boom CM is moved foreward, aileron servos are fitted in wings as close to CM as possible (that's 15g removed from nose part!).

As you said, the aerodynamics is essential for high throwing, but I think that a lot of kinetic energy is dissipated because of unneccessary tail movement. I spent a lot hours on designing a new boom shape, to increase the overall stiffness. I hope it would help to beat those 80m :-) anyway, the prototype with old fuselage had 70m throws. I will ask the owner to post his logs.

The nose is not so long as it seems to be, anyway, the whole mass is not placed at the tip of it, that's important.

And a bit more photos:

-First wing with new painting scheme. 155g with 2 DS09 AMD closed inside. Final weight will be around 265-270g.
Last edited by GCM_models; Feb 20, 2015 at 06:00 AM.
Feb 20, 2015, 07:33 AM
Aurora Builder
It looks really good! And 70m throws are great with that wing-sounds like 80m is possible

Is the wing hollow or solid core?
Feb 21, 2015, 01:09 AM
Registered User
Thomas Wang's Avatar
Looks so nice, and 70m is amazing high for me, hope I have chance to fly it.
Feb 21, 2015, 06:33 AM
Registered User
Nice. What does it cost?
Feb 22, 2015, 05:39 AM
Registered User
Thread OP
Hello everyone and thank you for the interest!

Wing is classic sandwich construction, not solid core one.

It's not published yet, but if you are interested, you can check the price in here: http://gcm-model.com/?page_id=240&preview=true

Have a nice Sunday.
Feb 22, 2015, 07:44 PM
Aurora Builder
Nice price!! Hope to see a few in person!
Mar 13, 2015, 05:59 AM
Registered User
Thread OP
Hello everyone!

I'd like to make a small report about the plane.

You can see, small defects in painting scheme, blue-red-white painting is very complicated thing to do. We are are still working on it, nevertheless, it's a second wing with that painting and it looks very nice in my opinion. What do you think?

You can see the surface, of the wings. It has mirror finish, because of vaccum assisted moulding technology. Visible "waviness" is a structure of biaxial fabric, it's not a wing surface. I will try to take better photos in sunlight when the winter's gone :-)

Now tails: full carbon set with weight bellow 13g.
Mar 13, 2015, 06:22 AM
Kyle Clayton
Wave Glider's Avatar
The hex tail socket is genius. The Ava had that and I always thought that was a fool-proof way of getting the correct alignment. Great work!
Latest blog entry: Helios and XXLite DLG
Mar 13, 2015, 07:37 AM
Aurora Builder
I'd be happy with that paint scheme! It looks really good!
Last edited by samc99us; Mar 13, 2015 at 02:30 PM.


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