Conference vmszoo::rc

    I am building from scratch a Piper Cub J3 (scale 1:6.5) with 3-function
    radio (rudder, elevator and throttle). In the actual building phase,
    I'll joint together fuselage, wings, elevator and rudder. Now, I
    am not sure about wing dihedral:
    
    I've glued together the two parts from the wing with a dihedral
    of 3 degree. But for my eye it seems not to be enough dihedral for
    an airplane without ailerons.
    
    If someone has experience in this question, any input will be helpful.
    
    Franz

Hi, there.

I didn't see anyone taking a shot at replying to your message, so I 
figured I'd give it a go.

Before I get into replying to your question, I must profess to being new 
at this "notes" business.  I have been given to understand that there 
are certain "rules of protocol" to be followed.  Unfortunately, the 
person who showed me enough to read notes has not yet had the time to 
explain all of these rules.  So, to you experienced "notes" people out 
there, if I inadvertently violate any of these protocols, please 
overlook it.

On to your question...

Your "eye" is giving you good information.  3 degrees of dihedral is, in 
general, probably a little on the shy side for three channel control.  
You would probably be lacking both stability and control.  Lacking in 
stability means that the plane would not want to hold a course 
(sometimes known as being "squirrelly").  Lacking in control meaning 
that it would respond very sluggishly to the rudder commands.

My suggestion is that you use 8 to 10 degrees of dihedral.

One final thought - I am assuming you are measuring dihedral with one 
wing panel flat on the table.  If you are measuring dihedral with each 
wing tip equally elevated from the table, and you are meaning that you 
have 3 degrees per wing half, then by my way of measuring you would 
actually have 6 degrees of dihedral - still a bit shy of what you should 
have.

Hope this has helped.

Ken 

      I too have a Kadet MkII that is being built for me by
    another noter.Before he started building it I asked him
    to put 2 insted of 4 inches of dihedral in the wing.I did
    this because 4 inches seemed like an awful lot to me.
    As soon as I find out how it rolls I'll let you know.
    It should be in the air by the beginning of October.
    
    
    Kevin

    I learned on a Kadet Mk II. I built the wing with ailerons, but
    used the coupling feature of my transmitter to put the rudder
    on the right stick and turn the ailerons almost off (essentially
    the same as blocking off the aileron servo and moving the rudder
    to the right stick).
    
    After an unfortunate mishap that resulted in a re-kitted wing,
    I built a new wing without ailerons. My recommendation is to build
    the Kadet as a 3 channel trainer with the dihedral and without
    ailerons, and then go to another 4-channel plane when you're ready
    for a 4 channel trainer. Overall, I am very pleased with the Kadet
    as my trainer, and I'm now on my 3rd plane, a zippy Super Sportster
    20. Furthermore, I have not rekitted another plane since the one
    and only incident with the Kadet, so I must have learned SOMETHING
    about flying from the Kadet (and my instructor, of course)!
    
    Dave Hughes

      Optionally, you might want to contact Wing Mfg., advertised in the
      hobby mags.  They sell foam wings for most trainers; one for my
      Eaglet is about $15, and this is pretty typical.  You could fit it
      with ailerons as an alternate wing.   I have Wing's catalog so if
      you want to pursue this further send me a message offline.

      Though I know that there are folks here who have forgotten more
      than I know, it sounds like your instructor was right; 4 inches is
      definitely too much for an aileron wing, and 2 inches is probably
      still on the high side, though it'll be a big improvement.  I've
      read that high wing ships usually don't have the aileron response
      they should have, and they often wind up being flown 3-channel
      style.

      Also, the problem of adverse yaw, where the upturned aileron yaws
      the plane in the opposite direction of bank, is more pronounced
      with a high wing. 

    The diehedral is not the only factor that limits the roll. The PT40
    trainer from Great Planes has a good 4 inches of diehedral in it
    for the 4 channel version. After learning to fly the plane I increased
    the aileron throw, and it would roll with no problem. Another aspect
    of the ailerons on the PT40 was differential throw, where you would
    get lot's of movement up and a smaller movement down with the aileron.
    I do not know the reason for this, but they do it for some reason.
    
    
    						Dave
    

    The reason for the differential aileron throw is to reduce the adverse
    yaw effect.  This is very common with flat bottomed airfoil wings
    like the PT-40.  I don't run differential throw on my Super Sportsters
    with symmetrical airfoil wings, but many kits suggest doing this.
    The down aileron has much more effect than the up one does.
    
    Charlie
    

    Norm
      I have also trained on the MKII but I had 2 inches of dihedril
    and found that it still didn't roll very well.What I've seen reading
    this entry is that the whole idea behind the MKII is an airlon trainer
    it is not a pattern ship or stunt ship buy no means.What my instructor
    told me was the reason why it did not roll was because it is a flat
    bottom wing and you could not get enough throw out of the airlon
    to get a half way decent roll out of it.I also found it very hard
    to fly it upside-down because of the dihedril.But like I said earlier
    was it is not a stunt ship.I found it to be a very good ship to
    get the feel of what the airlons did without turning it into a kit
    again.
      Hope this help's.
    
                                            KEEP'EM FLYIN
                                            JERRY

    I am currently building a Carl Goldberg Eagle II trainer and I have
a few questions about "too much" dihedral...

The Eagle II wing can be built with one of three dihedral options:

    2.25" - aerobatic aileron wing

    3.50" - trainer aileron wing

    6.00" - non-aileron wing

    The number of inches is measured from the tabletop to the wingtip
with one side of the wing pressed flat against the table.

    I built the wing on the A-Justo-Jig wing jig. I had the dihedral set
correctly for the 3.50" option. Hoewver, I must of bumped one half of
the wing out of position before I glued the two halves together, and the
wing came out with 4.25" of dihedral.

    Will this extra dihedral hurt the performance of the plane? I don't
want to butcher the wing trying to cut it in half unless I absolutely
have to.

BTW: The Eagle II has a flat bottomed wing.

-Jeff

    Jeff,
    
    I doubt the extra inch of dihedral will have any noticeable effect
    on the plane.  Ailerons 'could' be slightly less effective but I
    doubt it'd be enough to matter/notice much.    

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

  John,

  I have not built the Seniorita, but I did build the Senior.  If you are
going to add ailerons you should remove a lot of the dihedral.  I don't know
about the Seniorita has, but the Senior has 6 inches...of dihedral that is.
8^)  You should probably leave about 1 1/2 inches in for stability (come on
guys...correct me if I'm wrong).

  My Kadet Sr. is a great flying plane without ailerons.  VERY stable and
sssslllllllooooooowwwwwww!  It can do a snap roll in just under 3 mins. 8^)

  As for the best way to install ailerons....I'll let some else answer that
one.


		Jim
  

     Hello RC'ers! I am new to the sport/hobby of RC aviation,
but am really enjoying it! I have also enjoyed this notesfile. (I
thoroughly enjoyed reading the Ramblings!)  SO much so, that I am
hesitant to SET SEEN and have been trying to read through it! SO,
with that background/excuse, I would like to ask for some advice.
I hope I'm not asking this in the wrong place, or for a second 
time to this notesfile.

Here is the scenario...

     I built a SIG Kadet Senior (my wife bought it for me as a
birthday gift, best gift I ever got!) and I joined a local club. 
I got an instructor and learned to fly. Some folks in the club
talked me into building ailerons into the Kadet Senior, and
making it a tail-dragger. They also suggested I put a K&B 65
sportster in it. That is the current configuration. (In
hindsight, I think that these have been good recommendations.) I
have been practicing on my own. I can control the plane (more or
less, I still have a lot to learn) and am working on my landings.
The Kadet Senior has been a great first plane. I have been toying
with ideas to teach me to be a better pilot. I have decided that
it might be a good idea to build a second wing for the same
plane. I was considering making another wing with less (no?)
dihedral angle and more effective ailerons (my instructor says
that the current ailerons are poor, and I know what he means....I
didn't really know what I was doing when I built them and they
are mushy...)

     SO, now for the questions. What do you experienced pilots
think of the idea of a Kadet Senior with a "sportier" wing as
another step forward? Should I build it with less or, no dihedral
angle? Lastly, when building Ailerons, is it typical to "relieve"
the aileron so that there is a gap (on the bottom) when the
aileron is in the "neutral" position? I was going to make the
next set of ailerons something like the (crude) picture below,
what do y'all think?

                    advTHANKSance,

                          Eric
                                   
                                   
                 -----------/|-----------------------------
         --------          / |
      ---     Aileron     /  |    Wing
     ____________________/   |______________________________
                           ^
                           |
                           Gap in Question....

	Well I am not really going to answer your question but just add
	that I have had a Precedent HiBoy now for a year and put up
	well over a 1000 flights on it in that time. How I have kept myself
	interested in it is that I have modified the wings numerous times,
	either intentionally at home or unintentionally at the field. Now
	I did take my time but ended up with 4 wings with different sizes
	of ailerons, some with flaps etc. Great thing was that one always has 
	at least one wing spare. Then one must remember that some planes 
	probably won't like major modifications - possibly making them unstable.

	One thing I did in the beginning with this plane was to add a little 
	extra reinforcing - so as the odd bad crash occured I lightened the
	plane more and more - to get every last drop out of it. Well the 91
	sucks all and more out of it now ! But the 91 is temporary as its 
	going to gets its turn on the Acro Wot this week end. 	


	All in all the HiBoy with a recommended engine size of .30 - .40 has
	has a .40, .46 and now a, wait for it, a 91 4-S Surpass. Its lots of 
	fun with the 91 on it.....variations on themes ! Not that I would 
	emphasise or endorse putting 200-300 % more engine on a plane but 
	certainly, in your case, I would go for the top end engine size. That
	reminds me of my Viceroy - supposed to fly on a 40 sized engine ! That 
	was a year ot two back - I put a 91 onto it and it performed well - 
	although it didn't take to water too easily without floats.

	One think I have not managed to do is to get my wife to buy me a plane.
	And if see does it will be a day to celebrate 8-)

		
	To your question of ailerons - as you will see here different guys
	like different setups. Say-no-more. I think they have been dicussed
	somewhere else at length. Personally I center hinge all surfaces 
	with the pin type hinge. Gaps will reduce effectiveness of control 
	surfaces - so keep that in mind which ever method you go for. 

	Regards,

	Eric - and there was three !

    I looked through the keywords on beginner and wings and didn't find
    what I wanted,so here is the question. I've built my first trainer.
    Its a 25 size with a flat bottom wing and a span of 51". I fianlly have
    the name of a shop to looking for a club/instructor/field to learn. I
    bought a Sturdy Birdie wing kit ($14.00) and figure to use it first
    insted of the built up balsa wing on my plane. I have read all the
    horror stories about what goes up must come down ! The S.B. wing is
    foam with a span of 53" and the dihedral(sp?) is about a half inch more
    than the kit wing. Will this work or am I asking for trouble ? I built
    the balsa wing with aerilion(sp?) and the foam without.
    Tanks in advance for any help.
    Walt
    

    You should be alright but with proper instruction you shouldn't have
    too much to worry about with the built up wing. From what I've seen,
    the wing usually survives better than the fuselage in a damage causing
    crash. The extra Dihedral and wing area won't hurt you as long as you
    keep the wing incidence the same. In case you don't understand, you
    want to keep the imaginary line drawn from the farthest front point on
    the leading edge to the fathest back point on the trailing edge at the
    same level on both wings. If the new wing is semi-semetrical it will
    sit nose high in the wing saddle when compared with the flat bottomed
    wing and this will change the handling of the plane. Since you've
    already bought it, I'd fly the plane in the original configuration and 
    keep the Sturdy Bird wing as a backup and spend a lot of time with the
    instructor. Beginners airplanes get broken when the student gets too
    cocky and figures he can fly by himself and then something unexpected 
    happens and nobodys there to get him/her out of it.

    Walt,
    
    I'm assuming the airfoil and chord are similar or the same or close
    enough not to matter a great deal.  The extra dihedral should be of
    small consequence and it's a fact that when ailerons are used, you
    should also use less dihedral so it sounds like you should be OK with
    what you want to try.  Let us know how it works out.
						 __
				|      |        / |\	   	       
      	         \|/		|______|__(o/--/  | \	   	       
      | |        00	       <|  ~~~  ____ 04 ---- | --------------------
    |_|_|        (O>o		|\)____/___|\_____|_/	   Adios amigos, Al
      |     \__(O_\_	        |	  |___/	 o	   (The Desert Rat)

    I have a Sturdy Birdy.  The wing is a flat bottom wing with a flat
    platform at the saddle (no dihedral in the center two inches).  It has
    molded-in washout and is quick to build, ugly, sturdy, and effective. 
    Follow the directions; I didn't, I should have, and I regretted it.

    A club member called me last night posing the following question.  He
    bought an ARF semi-symmetrical, high wing, .25-size plane (can't remember 
    the exact model) and wanted to know if building it with zero dihedral
    would work.  He is a fairly experienced flyer, and wants a hot
    aerobatic ship to toss around the sky.  His concern was whether such a
    mod would work.
    
    I have previously built both the Eagle 2 and original Skytiger with
    about 1/4 to 1/2 of the recommended dihedral and found them to be
    slightly more aerobatic, but I've never gone all the way down to zero
    dihedral on a high wing plane, so I couldn't give him any real advice.
    
    I believe two issues will surface. One of course is the stability of
    the plane will change and it will loose any tendency to right itself. 
    But that must also be true of Cubs and Citabrias, which both fly well
    and are aerobatic.  The second is the possible need for differential
    aileron throw, but something tells me this is more an issue as dihedral
    increases, and at zero dihedral adverse yaw should be minimized.
    
    I also would think that dihedral has an effect somewhat like washout,
    ie, slanted wings are somewhat tip-stall resistant, and if you take out
    all dihedral, you may see a tendancy to tip-stall sooner.
    
    At any rate, I told him to call a few other pilots with more
    experience, but I'm curious about his question so I would like to see
    what others say.
    
    Thanks,
    Joe   

    I have reduced and removed dihedral on several shoulder wing planes.
    the only thing that changes is that the effect of the rudder is greatly
    reduced. The rudder will cause a rolling action on a plane with
    dihedral. Less dihedral less couple and more, (desired), yaw.  
    
    The plane will lose its ability to self-level if left alone. This is what 
    you want. The more neutrally stable a plane is the better. i.e. it
    stays where it is unless you give control input.
    
    E.

I agree with Eric.

>    But that must also be true of Cubs and Citabrias, which both fly well
>    and are aerobatic.  The second is the possible need for differential
>    aileron throw, but something tells me this is more an issue as dihedral
>    increases, and at zero dihedral adverse yaw should be minimized.

Cubs - even clipped wing cubs have dihedral - not a lot - but it's there.
I don't know about Citabrias.
    
Aileron differential (or the need for it) is caused by the airfoil and I
don't believe would be changed with dihedral angle.  The idea is the upgoing
aileron produces less drag than the downgoing one.  If the airfoil was 
symetrical I don't believe you would have any need for differential.
Experts correct me if I am wrong.

>    I also would think that dihedral has an effect somewhat like washout,
>    ie, slanted wings are somewhat tip-stall resistant, and if you take out
>    all dihedral, you may see a tendancy to tip-stall sooner.
    
I've never heard that analogy before.  It could be (to a small extent)
but I doubt it.  Anyway I have a new HLG that wants to tip stall and has
lots of dihedral.  It's for sale!

Bye          --+--
Kay R. Fisher  |
---------------O---------------
################################################################################

    One thing about a wing with no dihedral is that it looks funny... it
    seems to droop. Planes with a little dihedral look better in the air. 
    They also seem to "groove" better in flight. I was under the impression
    that even pattern planes are set up with some dihedral.
    
    Finally, I seem to remember that where the wing is mounted relative to
    the fuse centerline affects the behavior of the dihedral. That is,
    low wingers can have somewhat more dihedral angle and still have very
    neutral response (or do I have that backwards?). 
    
    There was a pretty good 3 part series on dihedral in the AMA mag a
    couple years ago. It was the same guy who did an article on spiral
    stability. I read it twice and still don't know what it is.
    
    Dave
    

    Sooner or later we will get into proverse and adverse yaw. Can't wait.
    
    EVL-1.
    
    Simply put:- If you have ailerons and you take out all of the dihedral 
    on a shoulder-wing plane it will work. If you only have rudder it will
    not. Have a good day!. :-).