HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Feb 10, 2013, 10:18 PM
Registered User
United States, CA, Livermore
Joined Jan 2012
931 Posts
well I goy my maiden off today. definitely had too much up elevon but at least I didn't nose dive. I got it flying with lots of subtrim so at least I know where the elevons need to be. I noticed the right one is more UP than the left one. Not sure if this is normal (motor torque?). I am going to re-do the elevons mechanically and get the trims closer to zero.

Still interested in how much fin is required as i asked above.
rhodesengr is offline Find More Posts by rhodesengr
Reply With Quote
Sign up now
to remove ads between posts
Old Feb 14, 2013, 02:04 PM
Registered User
United States, CA, Livermore
Joined Jan 2012
931 Posts
some more progress. I measured the elevon positions where it flew ok, used subtrim to get my servos at 90 degrees, set my trims to zero, and set the control rods to get my measured positions back. This scheme worked well. Now I am trying to fine tune the CG by doing the dive test. I think I need more nose weight. Its not recovering up in the dive test and I am getting some side-to side wagging (yaw?).

I am finding that with a 1300mAh battery mounted a full battery thickness forward from the plans, the CG is still too far back. I don't think I can move the battery any further forward: running out of foam. Thinking about seeing if an 1800 or 2200 would help: more battery weight and less lead.

Did you other guys with 1300's need additional nose weight? How much did you end up with?
rhodesengr is offline Find More Posts by rhodesengr
Reply With Quote
Old Feb 14, 2013, 04:27 PM
Registered User
United States, FL, Palm Beach
Joined Jan 2011
1,162 Posts
I have a 1500 3S and needed 1/2oz in the nose
viper522 is offline Find More Posts by viper522
Reply With Quote
Old Feb 14, 2013, 04:43 PM
Registered User
nofreee's Avatar
United States, CA, San Diego
Joined Jan 2012
251 Posts
Quote:
Originally Posted by rhodesengr View Post
some more progress. I measured the elevon positions where it flew ok, used subtrim to get my servos at 90 degrees, set my trims to zero, and set the control rods to get my measured positions back. This scheme worked well. Now I am trying to fine tune the CG by doing the dive test. I think I need more nose weight. Its not recovering up in the dive test and I am getting some side-to side wagging (yaw?).

I am finding that with a 1300mAh battery mounted a full battery thickness forward from the plans, the CG is still too far back. I don't think I can move the battery any further forward: running out of foam. Thinking about seeing if an 1800 or 2200 would help: more battery weight and less lead.

Did you other guys with 1300's need additional nose weight? How much did you end up with?
I always balance everything ahead of time, including the ESC, receiver and servos. If you push everything towards the nose you can get away with even lighter batteries. Myself and others I fly with use as small as 1000mah batteries just fine.

You can really notice the weight difference on a 1000 vs 2200 when coming in for hand catches. The lighter wing slows down much better and floats right in, the 2200's tend to come in much 'hotter'. Obviously, you sacrifice flight time, but you can still squeeze out 5 minute flights on the 1000mah usually.
nofreee is offline Find More Posts by nofreee
Reply With Quote
Old Feb 14, 2013, 05:59 PM
Registered User
United States, CA, Livermore
Joined Jan 2012
931 Posts
Quote:
Originally Posted by nofreee View Post
I always balance everything ahead of time, including the ESC, receiver and servos. If you push everything towards the nose you can get away with even lighter batteries. Myself and others I fly with use as small as 1000mah batteries just fine.

You can really notice the weight difference on a 1000 vs 2200 when coming in for hand catches. The lighter wing slows down much better and floats right in, the 2200's tend to come in much 'hotter'. Obviously, you sacrifice flight time, but you can still squeeze out 5 minute flights on the 1000mah usually.
Well I posted because I did what you said. I tried to layout everything before cutting but I didn't consider using a bigger battery. A photo of my build is a page back
http://www.rcgroups.com/forums/showt...52384&page=460

It does not show the nose area real well but I moved the battery as far forward as possible. It is about a full battery thickness further forward than the spec in the instructions. It does not balance without extra weight. If I am adding weight, I figure I might as well use a bigger battery. I can't see how it would balance with an even lighter battery.
rhodesengr is offline Find More Posts by rhodesengr
Reply With Quote
Old Feb 14, 2013, 06:00 PM
My dog ate my airplane
United States, CA, San Diego
Joined Dec 2008
241 Posts
Quote:
Originally Posted by rhodesengr View Post
some more progress. I measured the elevon positions where it flew ok, used subtrim to get my servos at 90 degrees, set my trims to zero, and set the control rods to get my measured positions back. This scheme worked well. Now I am trying to fine tune the CG by doing the dive test. I think I need more nose weight. Its not recovering up in the dive test and I am getting some side-to side wagging (yaw?).

I am finding that with a 1300mAh battery mounted a full battery thickness forward from the plans, the CG is still too far back. I don't think I can move the battery any further forward: running out of foam. Thinking about seeing if an 1800 or 2200 would help: more battery weight and less lead.

Did you other guys with 1300's need additional nose weight? How much did you end up with?
The CTH Guru Lee can probably confirm this, but I think what happened with your build which requires more nose weight than normal is your extra covering over the laminate with Monokote or Ultracote or whatever you used. The swept wing design itself presents lots of wing area behind the CG point, so when you put an extra layer of covering on it for color it added extra weight behind the CG. So unless you remove the extra covering which I would not recommend, you will need extra nose weight to get the proper CG for it to fly properly. Therefore, your best option is probably to go with a larger battery so that you will have functional weight in extra MAH rather than dead weight such as fishing weights. The plane may fly faster than other wings without the extra covering, but that's probably not that big of a deal unless you really want a floater of a wing?
sredlin is online now Find More Posts by sredlin
Reply With Quote
Old Feb 14, 2013, 06:40 PM
Registered User
United States, CA, Livermore
Joined Jan 2012
931 Posts
Quote:
Originally Posted by sredlin View Post
The CTH Guru Lee can probably confirm this, but I think what happened with your build which requires more nose weight than normal is your extra covering over the laminate with Monokote or Ultracote or whatever you used. The swept wing design itself presents lots of wing area behind the CG point, so when you put an extra layer of covering on it for color it added extra weight behind the CG. So unless you remove the extra covering which I would not recommend, you will need extra nose weight to get the proper CG for it to fly properly. Therefore, your best option is probably to go with a larger battery so that you will have functional weight in extra MAH rather than dead weight such as fishing weights. The plane may fly faster than other wings without the extra covering, but that's probably not that big of a deal unless you really want a floater of a wing?
Thanks. This makes sense. I guess its hard to tell how much the difference the ultracoat makes unless you try to balance without it first.
rhodesengr is offline Find More Posts by rhodesengr
Reply With Quote
Old Feb 14, 2013, 07:21 PM
AKA, Cheap Chiseler
Sculptor's Avatar
United States, FL, North Fort Myers
Joined Mar 2012
1,181 Posts
Quote:
Originally Posted by rhodesengr View Post
Thanks. This makes sense. I guess its hard to tell how much the difference the ultracoat makes unless you try to balance without it first.
I'm pretty new to combat planes that I showed up at my airfield with an assassin I gave it my flight instructor to fly in combat. So when he got done we cleaned the 'pop wings' off the leading edge

I also have the Titan, it's an assassin on steroids is 5 foot wide, flies no winglets. It was on this plane that I really learned how easy it is to get it out of balance. To this point I can suggest this, find the CG on your plane then touched the end of the wing and feel just how low little pressure it takes to make a tail heavy.

I'm sure you already know but whenever the CG is running through the first one third of the plane proximally the rest of the wing behind it is nothing but a big lever and everything in front of it is a really small lever. Just round numbers for the sake of illustration. Let's say that with 2 gr on the end of the wings makes it definitely tail heavy it would take 10 gr in the nose to offset. The wings have that much leverage advantage over the front of the nose.

It sounds like I'm preaching are talking to myself, a soliloquy I think they call that.

I don't fly these planes because I wanted combat no, they are just a beautiful airplane to fly.

If I left the impression Sir I know a lot of things about airplanes I don't, but I do know about leverage.

DJ if man can make it, kamikaze ace can break it!
Sculptor is offline Find More Posts by Sculptor
Reply With Quote
Old Feb 14, 2013, 11:27 PM
Registered User
United States, CA, Livermore
Joined Jan 2012
931 Posts
Quote:
Originally Posted by Sculptor View Post
If I left the impression Sir I know a lot of things about airplanes I don't, but I do know about leverage
definately more leverage behind the CG.

Well I played around with weights and batteries and found I could use no weights and a 2200 but I am already pretty far forward and i didn't want to make the battery slot wider. So I buried about 50 grams of leadin the leading edge. I was at 550 AUW before the lead so I am just about at the max suggested AUW of 600g. I'll test fly in the morning.

That first toss after making changes can be a little hairy
rhodesengr is offline Find More Posts by rhodesengr
Reply With Quote
Old Feb 14, 2013, 11:53 PM
Lee
PERFECT LANDING !!!
Lee's Avatar
USA, UT, Orem
Joined Jul 2004
9,242 Posts
Too much throw is confused frequently for CG problems. Both the CG and the throws are very important to how a plane flies. Most flying wings and deltas won't be controllable if they are tail heavy.

I can build Assassins that don't need additional weight added. Most of the Widowmakers get about an oz of extra lead in the nose to balance but they fly so well I don't notice the extra weight.

My favorite weights are tire weights but in the past I used buck shot in a hole that I filled with glue.

Lee
Lee is offline Find More Posts by Lee
Reply With Quote
Old Feb 15, 2013, 10:21 AM
Registered User
Joined Jul 2010
208 Posts
Another way to add weight to the nose is to bury 2 Vs of spare metal control rod along with the shock cord across the nose.

Adds strength as well as weight unlike lead~~~~WMs in particular can get very floppy noses if you play lawn darts with them!

You've seen the Assassin vs Brick Wall video, I would not try it with my WM!~~~~H
CaribbeanBlue is offline Find More Posts by CaribbeanBlue
Reply With Quote
Old Feb 15, 2013, 02:13 PM
Registered User
Backyard's Avatar
Tresure Coast Florida
Joined Feb 2004
275 Posts
No extra balast needed on my Widowmaker with a 155g 1800 mAh set back for perfect CG. Penalty is less "floaty" and more inertia at impact. I could lose 2 oz. with Viper's 1500 idea but the WM is a thinner airfoil and when I move it forward there would not be much foam left between the nose and the LiPo. Still I think the 1500 would be the best bet.

Quote:
Got to the big field too late to see the crew today but threw it up into 8-10 knot breeze anyway. Zero wind effect. Flew to altitude, no trim required. Very happy with the low rates (60%/50%, aleron/elevator of 1cm total travel). Great aerobatics and great glide even at a porky 18 oz. auw. Almost caught it once. I swear it will thermal! Maybe 15 minutes of fun @ mostly 1/2 - 3/4 throttle. No noticable heat from motor, battery or ESC.

But...the last of about 6 nose dorking bounces damaged the 1800 mAh LiPo. The cells have shifted and one may be puffed. Ok, it's definitely puffed. All three cells were 4.08 v and it took only 208 mAh to charge it completely. I don't think its dangerous but will watch it closely. I may try to use carbon rod inserted and glued in the first four inches of the nose because it definitely bends (folds) 45-60 degrees on impact. That's how the LiPo cells got shifted. Of course you engineers out there will say then it will bend at 4 1/2 inches and the rest of you will say "just learn to fly it and stop dorking it".
Backyard is offline Find More Posts by Backyard
Reply With Quote
Old Feb 16, 2013, 01:06 PM
Registered User
Canada, BC, Vancouver
Joined Feb 2012
652 Posts
I fried my esc the other day, 30 amp hobbywing funfly, guess i was havin too much fun with the zoom 370 lol. It didnt burn just shut down and wouldn't re start, good tging i have a pile of 8 from an old octo. Motor is fine tho, glad i picked it up
elliott000 is offline Find More Posts by elliott000
Reply With Quote
Old Feb 17, 2013, 12:18 AM
Lee
PERFECT LANDING !!!
Lee's Avatar
USA, UT, Orem
Joined Jul 2004
9,242 Posts
We have updated our website with a slightly different look and easier access to the building instructions and parts lists.

www.crashtesthobby.com

Take a look and tell us what you think.
Lee is offline Find More Posts by Lee
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
WALLY WING...no fins...flies great!!! gpw Foamies (Kits) 22 Sep 23, 2009 07:56 AM
Qjet Flamingo & Butterfly: A plane no one has!! romans1015 Parkflyers 6 Jan 29, 2004 05:05 PM
Qjet Flamingo & Butterfly: A plane no one has!! romans1015 Parkflyers 0 Jan 28, 2004 01:40 AM
Noob concept plane Mikey C. Foamies (Kits) 5 Nov 11, 2003 02:05 PM
It's a boat...It's a plane...no! It's flightship! MrBungle Electric Plane Talk 24 Jun 26, 2001 02:55 AM