Super Cub CG Problems Fixed - WattFlyer RC Electric Flight Forums - Discuss radio control eflight

Beginners New to e-power flying? Get the low down in here from experienced e-power RC pilots!

Super Cub CG Problems Fixed

Old 06-09-2008, 04:57 PM
  #1  
toons
Who, Me, Fly?
Thread Starter
 
toons's Avatar
 
Join Date: May 2008
Location: Florida
Posts: 99
Default Super Cub CG Problems Fixed

First off - this is a great site! Loaded with useful information and helpful hints for us newbie-types which I recently put to good use with a new Super Cub. In particular a post titled "Practice, Practice, Practice" by Ed Anderson (AEAJR in the forums) and several posts on CG problems by other authors, thanx to you all. Armed with this and several other posts I entered the world of r/c flying. I used up the first battery (1 of 3) just doing ROG t/o's and trying for a controlled crash landing with some success (you know how that goes) into some tall grass at the end of the driveway, about a 100 ft run.
The second battery was spent trying some controlled flight, then cutting the power and aiming the SC at some tall grass for the landing. Had my 'spazed out' control moments to say the least. But, even with full up elevator the SC would immediately nose over and make like a lawn dart when the power was cut to zero. Extending the forward flight out over the tall grass field the SC did not glide well with the power off, it just wanted to nose over and go straight down when stall speed was reached, again, even with full aft stick (note:trims were fine). On one really squirrel-ly t/o, while still over the hardtop and maybe three feet off the ground slightly nose high, I aborted the t/o and tried to glide 'er in, but being at slow speed she just nosed over and landed hard on the nose. Damage was slight, a cracked cowling which took the brunt of the impact. That ticked me off. I had to do something about the nose heavy condition. I should have done something sooner.
The third battery was spent trying to balance the SC, so when power was cut and stall speed reached she would settle in a level attitude. But, the wind kicked up canceling the rest of the day.
Two days later, yesterday, was a great day for flying, NO wind and three freshly charged batteries. Having had time to think about the CG, I started by scotch-taping two quarters to the horizontal stabilizer. The ROG t/o went very well. In-flight about six feet over the grass I cut power and watched as she glided, stalled and 'went in' slightly nose low with full aft stick applied. To make a possibly long story shorter, I started adding and taking away quarters and settled on three (pics below). The SC flew and glided like a charm. When stall speed was reached the Cub settled in for a three point landing!
The rest of the day and batteries were spent actually flying, doing slow-turn figure 8's, and two loops (one on purpose). My landings really stink and some hand-eye coordination things still have to be worked on but the Cub flies so much better with the CG problems worked out. Love it!
I don't recommend this as a solution for everyone, but like other posts here on wattflyer.com I'm just passing along my experience. Thanx
Attached Thumbnails Click image for larger version

Name:	IMG_0180.jpg
Views:	208
Size:	310.8 KB
ID:	68621   Click image for larger version

Name:	IMG_0183.jpg
Views:	254
Size:	59.6 KB
ID:	68622   Click image for larger version

Name:	IMG_0203.jpg
Views:	236
Size:	94.2 KB
ID:	68623   Click image for larger version

Name:	IMG_0204.jpg
Views:	229
Size:	94.5 KB
ID:	68624  
toons is offline  
Old 06-09-2008, 05:24 PM
  #2  
flydiver
Super Contributor
 
flydiver's Avatar
 
Join Date: Jan 2007
Location: Seattle, WA
Posts: 2,668
Default

Is that a STOCK SC? If so something is weird. It shouldn't need that much tail weight. Most of them just FLY right out of the box (ignoring the loose nuts at the sticks).

If you end up not finding ANY other problem that needs addressing I'd suggest gluing a couple carbon or bamboo skewers about 6" long in to the side of the fuse at the skinny tail part. You'll end up breaking it anyway on a cartwheel sometime. It breaks right in front of the horizontal stab. Learning to land in cross winds is entertaining that way. This at least would be a productive way to add some weight to the back.
flydiver is offline  
Old 06-09-2008, 05:40 PM
  #3  
toons
Who, Me, Fly?
Thread Starter
 
toons's Avatar
 
Join Date: May 2008
Location: Florida
Posts: 99
Default

flydiver -

yep, its straight out of the box!?!! I always seem to get the one that's different. The weight of the 3 quarters is 0.6 oz. Thanx for the add-on tip. I'll try that.

toons
toons is offline  
Old 06-09-2008, 05:47 PM
  #4  
zook
Member
 
Join Date: Mar 2008
Location: north west ga. mts.
Posts: 94
Default

Goodday Toons, My s/c is just on the other end. To resolve my tail heavy I painted cowling and nosecone it fly's so good this way, you may also want to rethink the way you are landing your cub! For me I cut power on finel to 1/4 till I'm only A few feet on runway keep wing's level then cut power and watch her land smoth!!!.
zook is offline  
Old 06-09-2008, 11:24 PM
  #5  
toons
Who, Me, Fly?
Thread Starter
 
toons's Avatar
 
Join Date: May 2008
Location: Florida
Posts: 99
Default

Zook -

Usually I would come in over the top of the tall grass, holding it off, while bleeding off airspeed, but as soon as it hit stall speed it just nosed over. Now, after the six-bits add-on, I can hold it off, bleed off airspeed, let it stall, and she falls flat instead of nose first. Hope that clarifies... thanx.
toons is offline  
Old 06-10-2008, 12:58 AM
  #6  
Sabrehawk
Member
 
Sabrehawk's Avatar
 
Join Date: Apr 2008
Location: Seattle, Wa. USA
Posts: 647
Lightbulb

Toons, what im reading here in your posts is not a nose heavy plane, but a heavy thumb on your elevator stick.
Your cub as it comes out of the box will balance perfectly with it's stock battery.

What you have been doing is stalling the plane by using too much up elevator too much of the time. The simple truth is that an airplane cannot stall on its own, you the pilot are the only thing that can stall it and you do that by pulling too much elevator which is slowing the plane till it stalls.
I read you said at some point that you had applied full up elevator. The only time you would ever do that is in performing an aerobatic manuver such as a loop, a snap roll, or a spin. Otherwise full up elevator is gonna get you into a stall every time.
An airplane will not lose one bit of airspeed by reducing throttle, even at it's lowest position the plane will be gliding at a constant airspeed so long as you leave that elevator alone. Nor will it gain any airspeed at full throttle, just as in the glide it will climb at the same airspeed it glides at at 0 throttle, and the same holds true when holding altitude at around half throttle.

So with all that said, take off those quarters and let go of the idea that your plane will stall when you reduce throttle, it wont, it cant.(Unless you pull too up elevator and stall it. And with those quarters on the tail you are indeed tail heavy and the plane is indeed flying slower than it should and is closer to the stall as if you were applying up elevator.
Think of the throttle as your climb, descent, and altitude hold control, and your elevator as the airspeed control. For that is what they actually do in the end. So the only time you should be applying elevator is in a turn to hold the nose level, and just a about 2 feet off the ground to slow the plane and flare the landing. Oh, and for performing some aerobatics.

So when you are coming in to land, leave that elevator alone and just keep the wings level, and if it's coming down too fast give it some more throttle, that will slow the descent. And only apply up elevator when its time to flare for the touchdown at about 2 feet.
Sabrehawk is offline  
Old 06-10-2008, 01:13 AM
  #7  
herk_1
Trash Hauler emeritus
 
herk_1's Avatar
 
Join Date: Sep 2006
Location: Maryland, USA
Posts: 515
Default

A few reactions that come to mind, FWIW:

1. A plane's nose is supposed to drop when it stalls. If you cut power and hold in full "up" elevator like you say, then yes the plane is going stop flying and fall to the ground. The advantage of having the plane balanced so the nose drops when that happens is, that if you will just stop holding in "up" elevator and maybe push in some power, the plane will naturally start flying again. It's call "stall recovery."

2. You're not supposed to stall the plane when landing. Or any other time, for that matter. Unless you're just testing the stall properties (while at HIGH altitude). Or doing some kind of maneuver not appropriate for a beginner. Keep the plane above stall speed at all times, from takeoff to touchdown!

3. Now might be a good time to learn how to balance a plane by setting the CG to a specific measurement. It's unfortunate that they don't specify a CG location for the Cub. But when mine was stock, it was about 2-1/4" aft of the wing leading edge (and I still use that setting) Embed a couple of pencils in a board, eraser side up, and set the plane on the erasers (at the wing underside), at a point that the plane balances with the flat bottom side of the wing (or the stab) horizontal to the table. Then measure the distance from the leading edge of the wing to the erasers. What do you get?
herk_1 is offline  
Old 06-10-2008, 01:27 PM
  #8  
toons
Who, Me, Fly?
Thread Starter
 
toons's Avatar
 
Join Date: May 2008
Location: Florida
Posts: 99
Default

Sabrehawk -
Herk_1 -

Thanx to both of you for your response... but I am actually stalling the SC on purpose! Maybe I should have made that a little clearer from the beginning. Being new at r/c flying I am not competent enough to land the Cub in a designated landing zone, such as my driveway or a mowed grassy area next to it, my control touch and hand/eye coordination isn't up to snuff yet, and the left/right thing coming nose-on still leaves something to be desired. However, I have several acres of unmowed field I can safely land/crash the Cub into without causing major damage to the plane. So, rather than make a normal approach and landing and hitting the tall grass/weeds (about 18 ") with forward airspeed, I decelerate just above the vegetation and let it stall, and fall relatively flat into the green stuff with as little forward speed as possible. Before the addition of the quarters, the SC would nose over when stalled. Now it drops flat. With the quarters in place the SC flies better and handles nicely at slow speed. Thanx again. - toons
(As info: I've been a rated pilot since 1964 with several thousand hours in helicopters and just over 200 in fixed-wing aircraft - I'm just new to r/c flying).
toons is offline  
Old 06-10-2008, 02:09 PM
  #9  
Sabrehawk
Member
 
Sabrehawk's Avatar
 
Join Date: Apr 2008
Location: Seattle, Wa. USA
Posts: 647
Thumbs up

Ahhh ok, thats cool then. Nuthin wrong with making a full stall landing when the landing area calls for it, I just didnt pick up on the fact that you were doing this on purpose, so rodger that.

Yeah heck in the real old days back in the golden age of aviation that was pretty standard practice to have the plane fully stalled at about 6 inches so that the plane was out of airspeed, and lift. And was where the term " Three point landing" came from. The planes were all taildragging biplanes and the idea was to have all three wheels touching down at the same momment, the plane being held nose high just barely above the stall.
That way it wouldnt tend to bounce back into the air as those super light old timers had a nasty habit of doing if they still had enough airspeed to fly.
Sabrehawk is offline  
Old 06-10-2008, 03:06 PM
  #10  
toons
Who, Me, Fly?
Thread Starter
 
toons's Avatar
 
Join Date: May 2008
Location: Florida
Posts: 99
Default

Sabrehawk -

Yeah, I know what you're saying... I learned in Cessna 140's and Aeronca Champ's... I liked the 'Air-Knocker' the best. Really, thanx for your input, and that of the other members, all flying tips and information is greatly appreciated.
I've noted other cg write-ups in various forums and just wanted to get my 6-bits in

- toons
toons is offline  
Old 06-22-2008, 03:56 PM
  #11  
toons
Who, Me, Fly?
Thread Starter
 
toons's Avatar
 
Join Date: May 2008
Location: Florida
Posts: 99
Default

As an update:

Flew the SC into my front porch railing (the left/right thing again) last week which pushed the wing almost a 1/4 inch aft of its original static position (no other damage to the SC, and was able to fly again immediately)... I noted the a/c now flew somewhat tail-heavy and removed the quarters. Flew great and in trim.
While ordering additional batteries from the online supplier I mentioned the cg shift and described the above incident. He told me he also had a SC (with no cg problem), and in comparing his to one of his walk-in customers SC (who also had a nose heavy condition), they noted the LHS guys wing sat further back in the saddle than the customers. The customer made the adjustment and solved his problem.
My wing now sits back to the point of almost exposing the forward edge of the ESC compartment.
Well, as of last evening, it makes little difference as the SC now adorns the seamingly unreachable very top of an 80 foot elm tree. Tried last night, this AM, and will attempt again later to get 'er back. Pilot error... poor depth perception. Frack!!!
toons is offline  
Old 06-22-2008, 04:34 PM
  #12  
Flyzit
Member
 
Flyzit's Avatar
 
Join Date: Jun 2008
Location: Mt. Laurel, NJ
Posts: 23
Default

I hate trees that jump out in front of you like that.
Flyzit is offline  
Old 06-22-2008, 04:43 PM
  #13  
pd1
Still Learning
 
pd1's Avatar
 
Join Date: Sep 2006
Location: North of Boston
Posts: 4,098
Default

No doubt about it.
Trees can catch our planes much better than we can avoid trees.

Hope you get back OK.
Paul
pd1 is offline  
Old 06-22-2008, 04:47 PM
  #14  
CHEECH
IN THRUST WE TRUST
 
CHEECH's Avatar
 
Join Date: May 2008
Location: Arizona
Posts: 305
Default

Hello Toons

Flying the foam cub, how well did it take impacts? Im in the same situation as yourself, except I went with the Wood. Wood Vs Foam what do you thingk. Mine is tail heavy, but with the added weight on the firewall it flew awfull. I lost the weights and it flew fine afterwards untill the motor spun off the firewall. I enjoyed your story. Thanks.

Im sporting a J-3 ElectriCub by Great Planes.

CHEECH
CHEECH is offline  
Old 06-22-2008, 05:42 PM
  #15  
toons
Who, Me, Fly?
Thread Starter
 
toons's Avatar
 
Join Date: May 2008
Location: Florida
Posts: 99
Default

Flyzit -
pd1 -
CHEECH -

Thanx guys... yeah, 'cumulus-tree-branches' - just another bad weather phenomena, but it's better than 'cumulus-granite'!!!

Anyway, its really jammed in up there... still trying...

CHEECH - I've only flown foam and it seems to stand up really well with the abuse I've put it through, even to the point of snapping the aft part of the fuselage (from just forward the elevator) completely off during a unscheduled cartwheel maneuver. Just some gorilla glue and packing tape put the thing back in flying order in less than 2 hrs. The wings where lightly dented and chipped from bashing into two other (but shorter) trees, and a couple of rough landings on the driveway. I'm really impressed with the way the foam has held up. Hope that helps.

-toons

Attached a pic... you can just make out the underside of the SC, hope you can see it!
Attached Thumbnails Click image for larger version

Name:	SC in tree.jpg
Views:	171
Size:	47.5 KB
ID:	70093  
toons is offline  
Old 06-22-2008, 06:05 PM
  #16  
Sabrehawk
Member
 
Sabrehawk's Avatar
 
Join Date: Apr 2008
Location: Seattle, Wa. USA
Posts: 647
Smile

Yep, them trees eat model planes for breakfast, and model rockets for supper, and have been known for having little balsa gliders for snacks.

Sorry bout this Toons, I been there and I think we all have sometime or another. But try this, just aim for that tree and you'll miss it by a mile.
Sabrehawk is offline  
Old 06-23-2008, 03:42 AM
  #17  
toons
Who, Me, Fly?
Thread Starter
 
toons's Avatar
 
Join Date: May 2008
Location: Florida
Posts: 99
Default

Sabrehawk -

Agree... but me thinks I'm dealing with 'Magnet-Trees' !?!!

No matter what I did today (threw things, launched fishing rod things, poking things, etc.,) it's still stuck up there. The wind today whipped the tree tops better than I could and didn't budge it an inch... frack!

Chainsaw is next...

- toons
toons is offline  
Old 06-23-2008, 03:55 AM
  #18  
John Seidelman
Member
 
John Seidelman's Avatar
 
Join Date: Aug 2005
Location: Oswego , Il.
Posts: 203
Default

Should be a sizable amount of firewood there.
John Seidelman is offline  
Old 06-23-2008, 04:41 AM
  #19  
Flyzit
Member
 
Flyzit's Avatar
 
Join Date: Jun 2008
Location: Mt. Laurel, NJ
Posts: 23
Default

I just parked my J3 Cub BL about 75ft up in a oak tree tonight. I'll pray for a hurricane.
Flyzit is offline  
Old 06-23-2008, 04:49 AM
  #20  
toons
Who, Me, Fly?
Thread Starter
 
toons's Avatar
 
Join Date: May 2008
Location: Florida
Posts: 99
Default

John Seidelman -

I'll let ya know how many cords of wood I get .

If you're a VET - WELCOME HOME JOHN... Thank You and glad you made it!

- toons
toons is offline  
Old 06-23-2008, 04:53 AM
  #21  
toons
Who, Me, Fly?
Thread Starter
 
toons's Avatar
 
Join Date: May 2008
Location: Florida
Posts: 99
Default

Flyzit -

I know how much that sux... guess we're both prayin' for a 'big-windy'... any chance of getting 'er down?

-toons
toons is offline  
Old 06-23-2008, 06:54 AM
  #22  
John Seidelman
Member
 
John Seidelman's Avatar
 
Join Date: Aug 2005
Location: Oswego , Il.
Posts: 203
Default

I thank you for the Welcome Home. US Navy 61-66
If I were in better health I would run out there and visit my son and grandkids in NH and make a side trip to help the cutting of firewood. We used to cut our own in the 80s when we lived in WI. Had a Homelite that did a good job for us.
John Seidelman is offline  
Old 06-24-2008, 01:09 AM
  #23  
Flyzit
Member
 
Flyzit's Avatar
 
Join Date: Jun 2008
Location: Mt. Laurel, NJ
Posts: 23
Default

toons: I'm gonna need help from Mother Nature for this one...unless John stops by with the Homelite. Cops may not like folks hacking down trees next to their soccer field though. We'll have to do it at midnight.
Flyzit is offline  
Old 06-24-2008, 01:56 AM
  #24  
CHEECH
IN THRUST WE TRUST
 
CHEECH's Avatar
 
Join Date: May 2008
Location: Arizona
Posts: 305
Default

Any luck with the rescue Toon N Flyzit?
CHEECH is offline  
Old 06-24-2008, 03:25 AM
  #25  
Flyzit
Member
 
Flyzit's Avatar
 
Join Date: Jun 2008
Location: Mt. Laurel, NJ
Posts: 23
Default

I'm considering blasting it out of the tree with my sons paintball gun.
Film at 11.
Flyzit is offline  

Quick Reply: Super Cub CG Problems Fixed


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

Copyright 2018 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.

Page generated in 0.10583 seconds with 18 queries