Larry AK cUB

For those of you who use 6inch dubros these might be abetter alternative .They are 6.5 inch and lighter 15.5oz for the pair justunder a lb dubros are 1lb 8oz a pair so 1 ½ lb for the dubros….These stay softin cold weather dubros get rock hard…They are 30bucks a pair. They can also bedrilled out for larger axles. I run the 8.75 inch on my H9 J3 and H9 P-18 and reallylike them. Those 11.6 inch ones would be nice on 1/3 scale or larger. If anyoneis interested here is Roberts email [email protected]
The 6.5 inch I would think would work great on ¼ scale cubsor a little smaller ones.

Larry AK cUB

For those of you who use 6inch dubros these might be abetter alternative .They are 6.5 inch and lighter 15.5oz for the pair justunder a lb dubros are 1lb 8oz a pair so 1 ½ lb for the dubros….These stay softin cold weather dubros get rock hard…They are 30bucks a pair. They can also bedrilled out for larger axles. I run the 8.75 inch on my H9 J3 and H9 P-18 and reallylike them. Those 11.6 inch ones would be nice on 1/3 scale or larger. If anyoneis interested here is Roberts email [email protected]
The 6.5 inch I would think would work great on ¼ scale cubsor a little smaller ones.

Larry AK cUB

Sorry a bought the double post I tried to edit the spelling and this is what happened

iflyfloats

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Larry,
What do the 8.75 inch tires weigh? And the cost if you
if you don't mind sharing? I have the 6 inch and wanted the 200 mm air tops but over my budget.

Larry AK cUB

The 8.75 inch are 2 lbs for a pair...Dubro 6inch weigh 1.5lbs a pair so add 8oz...now the 6.5inch the best deal for 30bucks a pair weigh just under 1 lb a pair....Cost of the 8.75inch around 125 a pair..more work and come with axles.Ihope he gets a web site going...Larry

iflyfloats

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Thanks Larry for the info

iflyfloats

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Just checking that I am doing this right, to balance my Cub I installed screw eye's (lift rings) at 4 3/8" measured from the leading edge of the wing into the top of the fuselage somewhat replicating the lift rings in the full scale
Cub, (located on the wing spar mount). I then suspended it and added weight till my spirit level bubble was centered, that was setting on top of the horizontal stabilizer. I've read where some have leveled the cockpit floor and
others used the trim stripes for level reference. This is my first model of this size and expense and I want to get it right.

flycatch

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Buy or build yourself a CG stand. You will find plenty of articles on this subject.

marksp

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Wow...I'd be scared either the string would break or the hooks would pull out!

My simple approach is to have 2 people place a finger at CG point on wing tip and lifting.

abelard

Those CG stands are pretty clumsy. I build two pieces of brass tubing into the structure horizontally -- at the wingtips for a mid or high wing, near the top of the fuselage for a low wing -- and plug two pieces of music wire into them, connected by a piece of tent cord. Works splendidly.

Alcuy

I am not sure anyone answered specifically the reference point for the level for iflyfloats. I had the same sort of question myself. I ended up using the horizontal stabilizer because in my thinking level flight would have the stabilizer somewhere near zero in the angle of attack at cruising speed. Another look at the bottom of the wing shows it pretty flat and might be another reference point as well. The wing and the stabilizer on my Cub is about 2/10ths of a degree difference positive on the wing with the stab level 0... And that is probably withing the margin of error in my setup... and it varies slightly depending where I measure it so maybe the struts are twisting the wing a tiny bit; or I am no good with my Hanger 9 digital angle equipment... Maybe his answer is buried in the ton of literature out there.

However, I will say that my Cub does fly just fine and looks pretty good in the air as far as its attitude in flight. And it does not exhibit any tendencies that would make me think it is not balanced correctly. I do know it is not tail heavy... and it does not seem to like or need a ton of speed when landing.

That said, if I go for the bush wheels, I work through getting it balanced again. Unless someone has better information, I will do it like I did before. I think I will get in touch with Robert. I can always shelve the Dubro wheels I guess. Thanks Larry AK cUB!

marksp

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Per the manual suggested 4"- 4 3/4" range, I'm at 4 1/4"; flies well for me.

I decided to order up a couple sets of the 6.5" PR Bushwheels. I'll switch out the 7" AirTops and see how she flies with less weight and less drag. I'm also keen to try them on my Hangar 9 DHC-2 Beaver which currently has the DuBro 6" big wheels.

Cheers

Larry AK cUB

We had a fun fly here in Alaska today and Robert brought aset of his 6.5inch tires and he fitted them to this e flight carbon cub on site.Had to drill out the hub a bit. But the cub needed no trim adjustments flewgreat the softness saved the landing gear a time of two. I think he is going touse flat nuts on the inside of the hub instead of nylon lock nuts and trim downthe length of the hub bolts so they don’t cause interference different types oflanding gear looks like he’s got a winner here. My axles were a tad too shortfor my H9 Taylor craft. But these are going on the Tcraft.

bikerbc

I flyfloats I did almost the same thing to balance my PA 18 I used the trim strips for a reference . The stab is positive by a few degrees as is the wing .. I am not sure about the cock pit floor . I like the lift ring idea . I put a 1/4" dowl sheathed with arrow shaft between the ribs 4 3/8" back from the leading edge ..Its held in with two screws run in from the out side. You can get a very accurate measurement this way . It worked great . I also built a venassa rigg . Sometimes I find when I am dealing with struts It is a pain in the butt to use but it sure works great . This lift ring system of yours should be great ..I am going to remember it ..

iflyfloats

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marksp,

I don't think there is much chance of the hooks pulling out as there are 2 layers of 1/16 plywood making up the top of the fuselage, I drilled smaller holes and screwed the eye's in and then removed them and put thin CA in the holes to harden the threads like you would for servos, I used 2, 20lb test stainless fishing leaders for the harness and the string is I believe about 70lb test. I use it at work to pull straight lines for building and have never broken it yet, and I pull it as tight as I can. I don't have real accurate scale but my fisherman's deliar reads about 17 pounds.

marksp

My Feedback: (9)

Right on!

My plane is 20% heavier than yours, but still flies great! Yours should be very agilee @ 17 lbs!

Cheers

Jeepindog

If you put the level on your horizontal stab then you just added TAIL WEIGHT to your "balanced" airplane. Another way to balance this particular airframe is to remove the top hatch and put a dowel (wood or steel) through the fuselage and into each wing, using the holes in the side of the fuse that match up with the holes in the wing panel roots. Run a box-end wrench over the dowel and have it facing forward so that it sits UNDER the wing tube inside the fuselage. The dowel and wrench will make a T with the bottom of the T pointing forward. If you wrap some grip tape around the wrench it will have plenty of friction for the next part. Now you can loop a length of stout cord around the wrench and suspend the entire airplane with the T you just assembled. You can use a Sharpie to make marks to locate the front and rear of the CG, then stick a two pieces of painter's tape between the two front marks, and two rear marks. When the Super Cub is hanging from the T the airplane should hang level, and the rope should be somewhere between the two tapes without touching either. Sounds a lot harder than it is. This is an extremely easy way to balance this particular airplane. Add weight as appropriate until the fuse hangs level with the suspension cord somewhere between the tapes.

Alcuy

Sounds good, (",,,is hanging from the T the airplane should hang level, and...") but what part of the plane is level? I mean no offense!

I think as you say the balance point is "between the tapes" it will fly just fine. I like your method very much! You do not necessarily need a reference point. I am assuming the tape is across the top of the hatch area parallel with the wing and lined up with the fore and aft marks under the wing (marks are top and bottom)?

In fact if we were to just finger balance it under the edge of the lower cockpit ledge between the marks (that should be made), and it appears to hang within a couple or three degrees of level, it will fly. (My uncalibrated eyeball cannot tell 1 degree increments) It may not be up to any particular individual's accuracy standards, but as long as it is not obviously low tailed or high tailed (or if you prefer, nose up or nose down), it will fly OK. It does appear the stripes are a good reference... close enough to start anyway.

The point I am trying to make is that if there is no exact proscribed reference point to be used to pinpoint the angle (attitude of the fuselage or of a control surface, etc...) to be zero/level, then all we are doing is ball-parking perfect flying level inside the range for the CG (with the hanging method). It will definitely be close enough to fly and slight adjustments can be made to the individual's taste after they have flown the plane. That is IMHO. We all would like perfect from the start but many times we have to settle for "good enough" until we can tune in on perfection.

Lets go fly!

Jeepindog

All things considered, and there are a lot of things to consider, if the Super Cub is balanced within the recommended CoG range then the horizontal stabilizer should be level in normal cruise flight. It also happens to line up pretty closely with the blue stripes on the side of MOST of the Hangar 9 1/4 scale Super Cubs. It's easy to forget that a Cub flies with a high tail- higher than most people think. Here's a "level" Super Cub. http://www.airliners.net/photo/Piper...per/1493110/M/

flycatch

My Feedback: (26)

High tail and just what is that implying. The picture, if you look closely, has the cub flying in horizontal flight with the horizontal stabilizer trimmed at 0 degrees. The H9 Super Cub has 5 degrees of positive incidence built into the cradle. This incidence was intentional to get the tail up rapidly off the ground. This took me by surprise on my first takeoff and it led me to believe my thrust line was off. After I gigged it up it became obvious what the designer had done and why.

Alcuy

Horizontal stabilizer set a few degrees one way or the other changes the angle of attack for the wing. A lot of things to consider for sure... I took into account the fact that the tail should be pretty close to level in level flight. If it was not, the plane would possibly need different trim settings based on its airspeed. Speed does not seem to affect my elevator trim at all for level flight at various throttle settings.

What is good here is that the Cub is a sedate and forgiving airplane to fly; be they the full sized or the scale variety. They won't keep you out of trouble, but they do fly well enough to let you have some leeway. So they pretty much look good and fly well no matter who the pilot may be.

The cub may look like it is flying with a high tail, but it is still below the main. It is an optical thing based on the way the fuse is built... It does appear level in the photo referenced.

Jeepindog

I'm not trying to get anyone to believe that the tail flies higher than the wing. That's just nuts. (Level in the photo I linked, not above the wing.) I'm only trying to help others figure out what "balanced" means in relation to the airframe. Using the tail as a horizontal reference point will yield strongly positive results. That's all. I don't care if Billy Bob thinks that the tail is built with toothpicks from the local diner, or that Jim Bob is certain that it was built backwards, or their cousin Cletus Bob believes with his whole hillbilly heart that the whole airplane was built upside down... I don't even care if anyone else likes this airplane. I'm only trying to say that it flies very well and that the horizontal stab is a great reference point for "level" on this airplane. If one were to gaze upon page 73 of their instruction manual it would show a pic that clearly demonstrates what level is. It looks like one could use the front arms of the landing gear or the vertical sections of the cabin windows are vertical references, and the tail as a horizontal reference.

iflyfloats

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Well I guess the reason I wasn't sure is because my manual only has 60 pages. Sorry I asked !

Jeepindog

That's a bum deal. Here you go: http://www.hangar-9.com/ProdInfo/Fil...540-Manual.pdf

Alcuy

Thanks Jeepindog... I was in the same boat with Bob on the manual and did not think to review the on-line version. Appreciate the link. And I sure did not intend to twist your tail either. But if I did I apologize.

Al