CG Problems - FT Versa Wing and Blunt Nose Versa Wing

[kiteboarder]

Last summer I built a regular FT Versa Wing. I loved. I recently took it apart to used the hardware in a fresh new Blunt Nose Versa Wing. Both Pushers.

However, I had problems with the CG on the first one, and I'm having the same problems on the blunt nose. Tail heavy.

For the regular Versa, because of the lack of space, I had to add small lead deadweights to the nose (an extra 20g). I was finally able to balance it out using those and a 2200 (240g). Total 260g).

However, with the extra space of the blunt nose versa, I figured I'd run a bigger battery instead of the added dead weight.

However, to balance it out properly, I calculated I need a battery that's around 340g - 360g! That's 4000Mah territory right there and I'm having a hard time finding one that's 20mm thick - As that's the biggest it'll fit. So I'm having a harder time balancing out the blunt nose than I did with the regular versa.

Regardless, I think I can get it done. This blunt nose versa will have no FPV or GoPro, so the battery needs to balance it out.

Am I on the right track? Can you point out a few 20mm thick big and heavy batteries? Any other suggestions to solve this problem?

 

[Craftydan]

yeah, the bluntnosed is designed for flying with heavy FPV gear, so skip it and you're that much farther behind the curve for balance.

One thing I've done in past is line the LE with straighened 16 gage wire for ballast and strength. really helps draw the CG forward. you can also work to make your versa a little fatter by forcing the LE fold to be less sharp forward.

I've found if I place spacer blocks on the upper surface, positioned to rest against the back of the spar I can get the desired fold repeatably. When folded, I can over-bend each of the creases then bow the curve out by sliding the rear upper pannel forward until the spacers press against the spar. I'll get everythign alligned dry, then put glue in the front two creases to hold shape, then glue the LE and spar, crack the back crease, remove the spacers, re-enforce the spar, then glue the back crease and TE. Nice solid wing with the desired curve every time.

For a thicker wing, use a strip of foamboard mounted flush to the rear crease (rear crease will be 5mm behind the spar).

Might not get you into 4000mah region, but it can help.

 

[kiteboarder]

Actually, a 4000mah would fit if you do that. I've found a few 4000mah between 20-25mm thick. I tried to go thicker than my old Versa. I found that creasing it further helped, but in the end, I need a thicker spar.

I'll be building another and I'll cut the spar a big thicker to help force the airframe to be a bit thicker.

That said, I'm trying to find the biggest mah battery I can find with the highest c rating (to add weight) but still keep it under 20mm thick. I'd found a few. I'll order soon.

I might still have to add deadweight, but not much. I wasn't expecting I would need that much more weight for the blunt nose over the regular Versa. Wish I had known that before I built it and I would've gone with a thicker spar right from the beginning.

 

[kiteboarder]

Note. Currently, the space in this build will allow up to a 20mm thick battery. However, the thinner I go, the more forward I can move it - equating to less weight needed. I've already found a 16mm and a 18 mm battery. If I go 16mm, I might not need 360 grams. Maybe 320g (guessing) as I can move it forward more.

 

[Bleumunkie]

I made a my first blunt nose and just pushed two batteries in there - half in the wing right in front of the spar, half in the cargo center. Twice the mah, no dead weight.

My second version I made a small dropped floor to add room. I can now easily stack two batteries, my top pin receiver, telemetry module, parallel wire adapter for batteries with room to spare.

I'll take pics shortly.

I just winged the mod, but could come up with instructions if necessary.

Edit - Pics:




Video Walkthrough:

 

[kiteboarder]

^^^ Hmm. Thanks for that idea. I still need to order batteries because my blocky standard 2200s won't fit inside the wing. But I have a list of batteries I'm looking at and haven't decided. See, I want the batteries to work on other models too. I found a good long 4000mah battery that's thin and long - perfect for the blunt nose versa. But unfortunately, it's so long that it won't fit my other models (maybe my tricopter can run it).

Before I order, I'll consider how I could run 2 batteries. That way I might be able to get 2 thin 2200s or 1800s that could be also useful in other planes.

 

[Bleumunkie]

^^^ Hmm. Thanks for that idea. I still need to order batteries because my blocky standard 2200s won't fit inside the wing. But I have a list of batteries I'm looking at and haven't decided. See, I want the batteries to work on other models too. I found a good long 4000mah battery that's thin and long - perfect for the blunt nose versa. But unfortunately, it's so long that it won't fit my other models (maybe my tricopter can run it).

Before I order, I'll consider how I could run 2 batteries. That way I might be able to get 2 thin 2200s or 1800s that could be also useful in other planes.

I got a notification that you replied right before I submitted my edit, check above to see what I'm talking about if you haven't already.


I will also note I made my center section about 1" thinner than standard flitetest - Didn't need the room!

 

[kiteboarder]

@Bleumunkie - Thanks for the detail. A big thanks for taking the time to take the pics and make the video. I'm busy here taking measurement for a solution... and planning ahead for the second build. I'll report back with my solution...

 

[TEAJR66]

I don't even worry about trying to get the battery inside. This one had a relief cut un so that the battery was recessed.

My last versa did not even get cut. Just had the battery strapped on top, way up front. Flew great. I just try to keep them off the bottom to save the abuse from landing.

 

[kiteboarder]

I'm actually quite disappointed with this blunt nose. I think I'm going to follow up with another regular Versa Wing and I'll chop it at the back-center at bit to move the motor slightly more inboard (an inch maybe?). I feel I can more easily add a thin an heavier battery to it to balance it out than with the blunt nose. See, I balanced my first Versa fine with one of the regular blocky Turnigy 2200mahs (25mm thick). Those are 195g. I only added an extra 25g of deadweight lead bits to the nose along with that. It would be relatively easy to find a thinner but wider and longer battery that weighs an extra 25g.

HOWEVER, with the blunt nose versa, I have been looking at every single thin 3S battery I can find on HK and I haven't been able to find anything that'll fit even with the large cavity. See, to balance properly, it needs about 385grams worth of battery in the compartment. If I push that weight forward, I can get away with 325-360 grams, but of course, no battery of that weight fits that far forward.

Finally, I decided not to waste money ordering batteries and I stuck one of the 3300mah 4S Glacier batterires (345g) from my tricopter and an extra 40g of deadweight to the front of the thing. Finally it balanced out. Not too happy I had to add that much weight.

But, we'll see how she flies. There's more wing area than the regular versa, but tons more weight. No sure what to expect. I'll flight it and see how I feel about it. Then I'll decide if I want to modify this design or go back to the regular Versa.

I still want to make this one work as later on I want to build one for FPV. That said, I can't see FPV gear fixing the problem as the weight needs to be much more far forward than FPV gear will do.

 

[Bleumunkie]

I can't speak for the regular versa as I've never built one, but despite the weight issue ( which the more I read is an inherent problem with wings in general ) I doubt I will ever build a regular versa.

I LOVE the bnv too much. I use the regular Turnigy 2200 20C batteries available for 9.99 with no problem.

Two balance slightly nose heavy which I prefer after experimenting. And I have removed one battery and taped an android phone to use as a video recorder in a pinch.

I'm going to get FPV gear soon, and the BNV is where it's going without question.

 

[makattack]

You may have a heavier or larger motor than I do, but my emax weighs in at around 55g, and I can fly my bnv with a3300mah 3s slim profile with fpv and apm gear without dead weight.

 

[kiteboarder]

I can't speak for the regular versa as I've never built one, but despite the weight issue ( which the more I read is an inherent problem with wings in general ) I doubt I will ever build a regular versa.

I LOVE the bnv too much. I use the regular Turnigy 2200 20C batteries available for 9.99 with no problem.

Two balance slightly nose heavy which I prefer after experimenting. And I have removed one battery and taped an android phone to use as a video recorder in a pinch.

I'm going to get FPV gear soon, and the BNV is where it's going without question.

I built this BNV with the same hardware that was in my regular Versa - Specifically, Hitec HS-55 Feather (blue) servos. The servos had no problem managing the Versa even at full speed - and it was fast. Do you think these servos will handle the extra weight of the BNV with 360 grams worth of battery? It will not have FPV this one, so it will be highly acro, therefore lots of stress.

I have e cheap metal gear servo I got from Altitude Hobbies. Maybe I should pair it up with another one for the follow up BNV build.

 

[kiteboarder]

You may have a heavier or larger motor than I do, but my emax weighs in at around 55g, and I can fly my bnv with a3300mah 3s slim profile with fpv and apm gear without dead weight.

I have an NTM 28-26A 1200Kv (57 grams).

I don't see why I couldn't cut a bit more into the trailing edge to move the motor forward a tad bit. After all, the elevons as so off to the sides it won't matter much. Mine is actually installed about half an inch more inboard than Josh Bixler's build video.

 

[Bleumunkie]

I built this BNV with the same hardware that was in my regular Versa - Specifically, Hitec HS-55 Feather (blue) servos. The servos had no problem managing the Versa even at full speed - and it was fast. Do you think these servos will handle the extra weight of the BNV with 360 grams worth of battery? It will not have FPV this one, so it will be highly acro, therefore lots of stress.

I have e cheap metal gear servo I got from Altitude Hobbies. Maybe I should pair it up with another one for the follow up BNV build.

I have the http://www.hobbyking.com/hobbyking/..._Brushless_Outrunner_Motor_AR_Warehouse_.html motor.

HXT900 servos.

So for weight -

Motor - 70g
Batteries - 188g x2 = 376g
ESC - 25g
Servos - 2x 9g = 18g

So weight besides airframe = 489g

I HAVE stripped servos. I will be going to metal gear servos when they come in on my next order. After saying that - I currently have HXT900's in there now, and it flies well. I am unsure if the stripped servos are a result of the BIG crashes I've had, or a cause. But either way - there is the info for you.

 

[kiteboarder]

Thanks so much for the info. That's roughly the same weight I'll be running. Though roughly 20 grams less. That said, the 9 gram feather Hitecs are inside the wing so there's no turning back now. Hope they hold. If they strip I'll do metal gears for the next build.

 

[Bleumunkie]

I just flew mine and was getting about 30 minutes per battery of flight time. So running two batteries like I am I was getting about an hour.

I am using telemetry and coming down at 10v.

Just as an FYI.

 

[Ron_Dog]

I'm building my Versa Wing and had to add 8 oz. lead to the front to get the c/g right with a single 2200 mah battery! My other option is to add a second 2200 mah battery,and run them in parallel! Mine is the "blunt nose" version,and as I type this I'm going to add formers to the front section,so it is deeper to hold the battery's.

 

[Ron_Dog]

yeah, the bluntnosed is designed for flying with heavy FPV gear, so skip it and you're that much farther behind the curve for balance.

One thing I've done in past is line the LE with straighened 16 gage wire for ballast and strength. really helps draw the CG forward. you can also work to make your versa a little fatter by forcing the LE fold to be less sharp forward.

I've found if I place spacer blocks on the upper surface, positioned to rest against the back of the spar I can get the desired fold repeatably. When folded, I can over-bend each of the creases then bow the curve out by sliding the rear upper pannel forward until the spacers press against the spar. I'll get everythign alligned dry, then put glue in the front two creases to hold shape, then glue the LE and spar, crack the back crease, remove the spacers, re-enforce the spar, then glue the back crease and TE. Nice solid wing with the desired curve every time.

For a thicker wing, use a strip of foamboard mounted flush to the rear crease (rear crease will be 5mm behind the spar).

Might not get you into 4000mah region, but it can help.

Dan,that's a great idea,putting the 16ga wire inside the leading edge! I will have to remember that trick on the next build! I think the next one will be the regular Versa Wing. The Blunt Nose I built, needs to have a lot of "ballast" in the nose even with 2 batterys,and moving the motor mount forward a inch! The wire trick might just tip the scales,and require less ballast in the nose. RD

 

[Ron_Dog]

Just a update on the Versa Wing Build.

As bad as I hated to add ballast to the wing I had too! I cut a slit infront of the battery compartment,and added weight. It now is slightly nose heavy,with 2 2200 mah batterys in the compartment! Not what I wanted,but it will have to do!