Conference vmszoo::rc

RE:	< Note 1006.0 by BTOVT::WHITE_R >
                            -< Ultralight model ? >-

>    				Does anybody know how he can check the
>    CG on this model or is it even necessary to do so?  


  I don't know how to check the cg on this particular model, HOWEVER, it
is absolutely necessary to have a properly balanced model.


  Jim

    Robert,
    	I saw an Ultralight model at Peanuts Hobby Shop and if I 
    	remember right, it had tail feathers.  It sounds like you
    	are looking into a flying wing.
    
    Ken

    The first ultra-lights were nothing than a hang-glider with an engine
    grafted on.  Consequently, most looked about the same as the
    conventional, tail-featherless, Rogallo-winged hang glider, with
    the possible exception of the addition of a rudimentary landing
    gear.
    
    I _know_ that COX marketed a model of one of these (radio was installed
    inside the dummy-pilot), perhaps others did as well.  Unfortunately,
    I haven't the foggiest notion where the CG should be...sorry.    

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

    re .2
    
    Ken,
         the ultralight you saw in the hobby shop is the one I am speaking
    of and it does not have tail feathers (unless you want to count the
    fanny of the dummy pilot!).  Peanuts asked me to enter the note on this
    unit before he actually tries to fly it himself.  Like in reply .3, the
    unit has a dummy pilot but the servos are mounted on a small block
    above the dummy's head.  Anybody know how hangliders check their CG
    before takeoff?
    
    Robert
    
    

    I don't know how hang-gliders check their CG but I would like to
    venture an educated guess; perhaps Tom T the king of heli's could
    add to this.
    
    On heli's the main shaft is used as a datum - you hang the heli
    from the mainshaft ( usually the flybar ) and adjust the fore/aft
    weight distribution until it is slightly nose down.
    
    Hang-gliders often have a king-post don't they for rigging the wing?
    
    I wonder if the same sort of balance procedure might give a useful
    starting point i.e. hang the glider from the king-post and adjust
    the weight distribution until slightly nose heavy.
    
    As I said at the start this is only a guess FWIW.
    
    Regards
    
    Brian
    

    
    	From the description of the model, I assume that you have a hang
    glider that resembles a flying wing.  If thats the case, I can offer
    a couple of suggestions.  As a point of interest, I have been flying
    hang gliders for 12 years (I've owned 6 gliders) and ultralights for 5 
    years so I do have some experience with them. 
                       
        Hang gliders are built with a specific "hang point" or CG defined by
    the manufacturer. If the CG has to be adjusted, it is NEVER moved
    beyond the manufacturers recommendations. The adjustment range is
    about 3 inches total across a root chord lenght of about 7 feet
    The numbers will vary with the glider design.    
    	Where the CG should be on a hang glider??  What we do is this....
    assuming you are within the weight range of the glider, if the glider
    flies too slowly, ie the CG is too far back and that results in
    you always pulling in or holding your weight forward, then land
    and move the CG forward 1/2 inch.  If you are flying to fast, the
    CG is too far forward and you end up pushing your weight back all
    the time...very tiring.  In that case, when you land you move the
    CG back 1/2 inch.   Repeat this proceedure until the A/C trims out
    correctly...hands off flying speed is 2-3 mph above stall speed
    and the control bar is positioned about chin high.
    	Your case is a bit more difficult.  You don't know the mfg's CG
    range.  The idea of starting at the Kingpost is excellent.  I'd
    modify that idea just a bit.  The CG is usually just in front
    of the kingpost.                           
    	If you have access to a windy hilltop, you can perform a check
    that all glider pilots do when launching their A/C.  We hook in,
    then adjust the angle of attack for zero lift.  The glider will
    weathervane into the wind.  Raising the nose will increase lift
    and with a good hard push, off you go into the wild blue yonder.
    You can accomplish this same trick with a model hang glider by tying a 
    string to the suspected hang point(cg point) and fly the a/c like a kite.
    if the cg's right, the A/C will easily float.  If teh cg's wrong,
    the hang glider will flop around like a fish out of water.  One
    word of advice.  do this is the smoothest wind conditions possible
    and hold the glider above your head to get it out of turbulence.
    
    				send mail if you need more data   
    
    						regards
    
    							Bob
    
    	
    

    
    	Couldn't find the other note so I'll put this little rambling
    in here.
    
    	Last night I had another opportunity to go up in an Ultralight.
    As before, it was FANTASTIC!  Not only did I go up, but I actually
    got to fly the thing!!!  I'm seriously hooked and will be purchasing
    one hopefully in the near future.
    
    	I noticed, as with remotes, that very little stick movement
    gives adequate response.  Just tip the stick to the left and away
    you go.  This ship being only a two axis control (rudder and elevator)
    does not turn very sharp.  As with our models, it basically slides
    around.  It does have spoilerons on it though and when used with
    the rudder produces the needed drag for a sharper turn (but we didn't
    use them).
    
    	I tell ya, these things are great!!!
    
    Ken

    Hey Ken,
    
    also order an ultralight RC and paint it the same color(s) as your real
    McCoy and fly into shows with a bang!
    
    Robert

    Well, its almost been a year since the last reply, and I still don't 
    own an Ultralight.  However, last night I went up again.  The only 
    problem was the wind....it was gusty.  Needless to say I was very
    nervous.  The landing was a bit rough and at one point we were blown
    off track at about 4' up.  A quick thrust of power and some rudder
    and we were back on track.  A bumpy landing and we were down.  I was
    relieved to be back on the ground.
    
    Saturday we're going to do it again.  My 10 year old daughter wants
    to go up real bad!  So maybe on Saturday she'll get her wish.
    
    Ken

    re -.9
    
    Ken,
    
    I'm no pilot, and I don't wish to spoil your fun or enthusiasm, but I
    would think long and hard about what you want to do with an ultralight,
    especially if you intend to take your daughter up in one.  About two
    weeks ago, we had a man killed in one, flying out of Stow, MA.  I've
    watched a take off where a puff of wind very nearly sent the thing into
    the tree tops, and the pilot into the hereafter.
    
    Tony

    Thanks for the concern Tony.  The pilot of the ultralight is a good 
    friend of mine and a very good pilot too.  I trust his judgement and
    skills enough to allow my daughter to go up with him.  I know
    ultralights are susceptible to the weather and that is why she didn't
    go up the other night. 
    
    However, on Saturday the weather (wind) couldn't have been any better,
    and she got her first ride in the ultralight as did my younger brother.
    She loved it!
    
    I got to pilot the thing for about 15 minutes.  I was really amazed as
    to the ease of handling it.  Turns did not require very much elevator
    to keep the nose up.  It was almost like flying our models, except the
    fact that I was in it when I made the turns.  What a blast!
    
    I realize the concern for life and limb when it comes to these flying
    machines, but the ratio of accidents versus the number of ultralights
    flying is very small.  And most accidents were caused by carelessness
    and stupidity.  We had a DEALER break his back last summer during a 
    test flight.  I later found out that he converted a two seater to a 
    one seater paying no attention to CG.  He was tail heavy on takeoff,
    got up about 75' and stalled it, tried to level off only to come nose
    down.  I also learned that he never does pre-flight checks.  I'll never
    deal with him thats for sure.  
    
    Ultralights are quite the thing here in Northeast Vt. and are becoming 
    even more popular.  One only needs the proper training and some common 
    sense to keep from an early demise.
    
    Ken
    

    
    I'm looking for an answer to a question I have on building my
    ultralight. The prints tell me to "set the wing at 7degrees angle
    of attack. Let me give you some more detail on the plane. The plane
    is a Mitchell U-2 flying wing with no tail feathers, it has a relaxed
    airfoil this helps in stability and creates an stabilizer effect, and
    it has a nose wheel (trike). Does this setting of 7 degrees raise the
    leading edge or trailing edge and is the wing cord line  what I use
    for reference?? 
    Thanks for all your help, this is alot of fun, it's like building a
    giant RC plane.... hey what would it cost to put a remote controll in
    this thing??
    
    Bruce
    

RE: <<< Note 1006.12 by DNEAST::MALCOLM_BRUC >>>
    
>    The prints tell me to "set the wing at 7degrees angle of attack.

A note on terminology. Angle of attack (AoA) usually is used in the context of
measuring the chord line to the relative wind. Angle of Incidence is usually
used to define the angle of the chord line to the aircraft longitudinal axis.

>    Does this setting of 7 degrees raise the
>    leading edge or trailing edge and is the wing cord line  what I use
>    for reference??

Raise the leading edge, and yes the angle should be with the mean chord line.
						-- Tom

One of our club members (Jack Buckley) flies R/C Ultralights (yes, 
full size) for the army.

If it is a +7 degrees (which I would expect), then you raise the LE of 
the wing. The reference line on the wing is the line between the 
furthest point forward on the leading edge to the point of the trailing 
edge generally. The easiest way to do it is to set it on a level surface
and use a level and a protractor to get the angle. Basically you're 
looking for a BIG Robart incidence meter. Find a long enough piece of 
aluminum and you could probably use one!

    Do the plans say POSITIVE 7 degrees or NEGATIVE 7 degrees. And is this
    a full size ultralight your building or an RC kit.
    
    I would "assume" it's positive but BE SURE. Espically if YOUR going to
    be hanging under it.

    
    All it said was "wing is set a 7 degrees angle of attack". I assume
    it meant positive (leading edge raised) but how can the nose of the
    plane lift if the leading edge is already at angle. I think of when
    I put floats on my Cub I had to have the incedence negitive (meaning
    the tail raise) so when I went to take off the floats lifted in the
    front. If the incedence was positive the floats would try to submerine.
    I'm not much into the theory of flight so try not to confuse me all
    the theories.
    I can give the guy a call and ask him to make sure.
    
    Thanks again the help
    Bruce
    
    The Mitchell U-2 is a full size one person ultralight with a 34'
    wingspan and a 22hp Zenoah 2cy pusher engine. empty weight 220 lbs.
    stall spd 25 mph, cruse 60 mph and top spd is 85 mph. The design
    was in the late 70's early 80's. 
    Some guy bought the kit all the nuts, bolts, cable, fabric, engine,
    prop, everything exept the gas tank and paint. He never touched it
    he told me he couldn't understand the prints. So I made him an offer
    and he didn't refuse. And I'm having a blast.8*)
     

Did you cut the ribs yet? How'd the cutting go?

Jim

    Bruce, based on the way other ultralights look, it must be 7 degrees
    positive incidence (angle of attack). Ultralight wings don't really
    "generate" alot of lift like a true airfoil. Instead, it relies more
    on the angle of attack to keep the thing flying.
    
    Steve

    I wouldn't have to worry about crashing if I got one of those.  My wife
    would shoot me on sight!
    
    Charlie
    

    
    I promised my wife I would buy a balistic paracute before I flew it!!!
    
    I would like to see how much an RC unit would cost for it.
    
    Bruce
     

    The guy I know (Jack BUckley) uses a Futaba radio and 1/4 scale servos.
    I don't know if he has any servos on there that are larger than that. 
    He does RC parachute drops for the Army.  Sounds like a fun job to me.
    
    Charlie
    

    Drove home last night what a crazy storm rain, sleet snow... what a
    nice night to skin the leading edge of my ultralight!!:-))
    get 1 CUP of 24 hr epoxy T-88 mixed 3/4 of the stuff put on and.....
    power goes off. :*<< had to get the flashlights out finish applying the
    epoxy then put the ply/skin on, strap it down to form fit ribs awg
    what a night. I'll get home tonight to see how much damage there was.
    All in all I think it went OK. 
    
    Bruce
     

Keep us updated as to your progress. You've asked enough questions 
that we're interested in the results.

Jim

    I hate it when that happens. :-(  Lights out during a critical
    operation.  Hope the patient lived.  Seems like I always get a phone
    call right when I mix up a bunch of 5 minute epoxy. 
    
    Charlie
    

    Just ask the caller to wait 4 minutes. :-)
    
    
    Would I fly in an ultralite that Jim C. built? Nope, 'cos he'd never
    finish it!
    
    Would I fly in an ultralite that Dan Weier built?. Nope, 'cos it pulls up
    in the middle of rolls.
    
    Would I fly in an ultralite that Charlie built? Nope, 'cos it wouldl be
    too pretty to scratch.
    
    Would I fly in an ultralite that Jim Reith built? Nope, 'cos the
    engines  would not run :-)
                                                      
    Would I fly in an ultralite that Steve built? - Nope, 'cos the
    polyester resin would have killed the foam. :-)
    
    Would I fly in an ultralite that Rene built? - Nope, 'cos it would
    always land in a tree.
    
    Would I fly in an ultralite that Charlie Nelson built? - Nope, 'cos it
    would have two wings and a radial engine :-)
    
    Would I fly in an ultralite that Dave Walter built? - Nope, 'cos it
    would be a glider :)
    
    Would I fly in an ultralite that I built? - Nope, 'cos I'm chicken!
                                     
    Mornin all.
    
    EVL-1
    

    >> Would I fly in an ultralite that Dave Walter built? - Nope, 'cos it
    >> would be a glider :)
    
    Hey, no problem, I'll strap on a Cox .049 for ya'!
    

    WIMP!
    
    
    
    

Maybe he's afraid they'd have to reclassify it something other than 
an Ultralight!

    
    E.
    
      If you would even THINK of rolling an Ultalight, you are crazier
      than I thought! :)

    Ultra-light. Jim R. was close. With me in it the definition of light
    would come into question. Of course you could also imagine a
    "side-by-side" with Jim R and EVL-1 in it. :-)
    
    Define that if you can.
    
    E.
    
    P.S. I said Bud-lite not THUD-lite!.
    
    P.P.S. I lost ten pounds of weight during the ten days of my house
           move - no joke.
    

See what happens when you unplug the refridgerator?

>    Ultra-light. Jim R. was close. With me in it the definition of light
>    would come into question. Of course you could also imagine a
>    "side-by-side" with Jim R and EVL-1 in it. :-)

I'd call it a car 8^)

>    Ultra-light. Jim R. was close. With me in it the definition of light
>    would come into question. Of course you could also imagine a
>    "side-by-side" with Jim R and EVL-1 in it. :-)

How about, "Unmanned flight"?

    It would need to be a twin-engine ultralight to handle the load. ;-)
    
    -Joe

Probably need to refit the emergency chute as well 8^)

Have to revisit the concept of "usable payload" as well!

    
    Well it's been along time since my last reply, I have some good
    news and some bad news... The good news is planes comming along
    nicely. The wings are all done need to sand and apply poly to 
    the uncovered areas of the ribs. Most of the welding is done.
    Started building the stabilators New Years day. Once those are 
    done I will assemble the Fuselage to the wing and install the 
    instruments. I'm in hopes to begin covering in the early spring.
    
    One slight problem The doors (6.1/2 feet wide) are not wide 
    enough for the plane to come out. 8-{{ I'll have to knock down
    the wall and put larger doors in.!*#@$%*#@
    Oh well I guess it could be worse??
    
    Bruce
      

I notice it's the HOUSE being modified... 8^)

    
    I haven't told my wife yet. 8^))
    

    Bruce, I had the same experience in building the KR-2.  The wings
    attached to a 9' center wing section which was part of the fuse.  I
    took out two sliding doors and turned the fuse at a 45 degree angle and
    assembled the attached wings outside.
    
    Is this possible with your plane?
    
    Hope this helps!
    
    Ollie

    
    
    Ollie,
    
    Nope it won't help. I'm building a flying wing. With the outboard wings 
    detatched it's 22' long and at midship from trailing edge to the front of
    the fuselage it's 8.5'. No matter how you angle it you gotta have a 9'
    opening. Building it isn't a problem it's getting it out!! Thanks Ollie
    for your input!
    
    Bruce
     

>    Nope it won't help. I'm building a flying wing. With the outboard wings 
>    detatched it's 22' long and at midship from trailing edge to the front of
>    the fuselage it's 8.5'. No matter how you angle it you gotta have a 9'
>    opening. Building it isn't a problem it's getting it out!! Thanks Ollie
>    for your input!
>    
>    Bruce

Suddenly I have this sudden desire to see a picture of this bird.
Can you scan something and point us to a postscript or .GIF file?

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

I saw pictures at the Sydney ME Gremlin contest (nyah-na-na-na-nyah 8^)

It's tough to describe but it looks like it'll be exciting to fly. Going through
the stuff got my home-built juices flowing again (I designed my garage with a
16' opening 8^)

Now where'd I put that spare time?

    	I'll take a look through my Ultralight mags tonite and see if I can 
    find a picture of the Mitchell Wing U-2.  Basically it's a flying wing 
    with a pod under the wing for the pilot.  The engine is mounted behind and
    slightly above the wing. The elevons are mounted above the trailing
    edge of the wing(I think).  I'm sure Malcolm can do a better job
    describing the aircraft.
    
    	FYI... The Mitchell Wing U-2 holds the world record for altitude
    in an Ultalight aircraft.  In the early 80's a U-2, with FAA permission 
    and an oxygen system for the pilot, achieved an altitude in excess of 
    28,000 ft somewhere over the southwest, possibly Nevada.  I'll try to
    find that article too.
    
    				regards
    				Bob
    	   

    
    ya did good bob,
    
    The Mitchell U2 is like a mid wing plane the stabalaters are mounted
    under the trailing edge. The pod design is the Mitchell B-10 I saw
    that fly at the Sun'n Fun in Florida '92. 
    I just forwarded to Kay Fisher a postscript file of the U2 hope he
    gets it OK. 
    Bob is correct in that the Mitchell flying wings have several world
    records both in hight and distenses.
    
    Bruce
    

	Here's some info on the Mitchell Super Wing U-2 taken directly from 
the November 1983 issue of "GLIDER RIDER", the World's oldest and largest 
Ultralight magazine.  The info is from a "buyers guide to plans-built 
Ultralights".
	
	In keeping with the purpose of this notesfile, I'll make the following  
model airplane type statements. :-)

  o	This is one heck of a plane to build from scratch.  
  o	Wonder how much CYA it'll take to build.
  o     Can I use my Tower Hobbies heat gun to shrink the wing covering?
  o	How do you hand lauch this sucker on it's first few flights to check 
		it's trim?

	Reprinted without permission.
	
	MITCHELL SUPER WING U-2
	Mitchell Aircraft Corporation
	1900 S Newcomb
	Porterville Ca 93257
	
	Price of the plans, $95

	Specifications:
		Empty Weight	200lbs	Height	    ---
		Wingspan	 34ft	Length	    9ft
		Wing area	136sqft	Fuel Cap  2 gal

	Recommended powerplant	Engines of 10 to 30 hp
	
	Performance:
	Stall   26mph	Gross Weight	430 lbs
	Cruise	60mph	Climb Rate	400 fpm
	Vne	82 mph

	Description:
		The U-2 is another flying wing design from Mitchell.  The 
	fuselage in the middle of the wing is built of 1/2 inch Chrome-moly
	tubing that surrounds the pilot area.  The remainder of the aircraft
	is constructed of wood and foam, then covered with Dacron and heat 
	shrunk.  An economy building kit is available for the U-2 for 
	$2,295.  A homebuilders kit can be purchased for $1,895.  Both kits 
	are priced without powerplants.  Time to build is said to be 275 hours.
	
	Comments:
		Approximately 350 sets of plans have been sold for the U-2
	with several flying.  It is said to be a difficult aircraft to build. 
	The plans package is similiar to the B-10.

    Bruce....
    
    	Here's a belated reply to your request for info in note 1006.12.
    You asked what was meant by "setting the wing to a 7 degree angle of
    attack" (when you're building a flying wing).   
    	I went through some of my old Ultralight mags looking for the article 
    on the U-2 world altitude setting flight. I found the article last
    night and in the description of the modification made to the aircraft 
    to support a world record altitude attempt, the builder says(this is
    an exact quote from Ultralight Aircraft mag, May 1984, pg 37)
    
    	"Other modifications helpful to the flight included installation
    of an engine fairing, mounting the canopy in reverse for more head room
    and a streamlined appearance, elongating the nose cone, extending the
    main landing gear legs by one inch to reduce the 3 point angle of
    attack from 7 degrees to 3 degrees(thus permitting higher touchdown
    speeds in strong winds), moving the axle pont back 2 inches to place
    more weight on the nosewhell for better ground handling......"
    	
         I interrpet this to mean that the 7 degree angle of attack of the
    wing is measured from the chord of the wing at the root section to a
    line parallel to the ground when the aircraft is sitting on a level
    surface and ready to fly.
    
	If anyone wants me to enter the full text of the article I will. 
    Mr Moderator, would it be in keeping with the nature of this notesfile
    to describe how a giant model airplane went about 5 miles straight up
    with it's pilot on board?   I do believe that the only reason someone
    would get onboard a model airplane and fly it up to 25,300 ft is because
    the batteries in his transmitter were weak :-)
    
    

>    I do believe that the only reason someone
>    would get onboard a model airplane and fly it up to 25,300 ft is because
>    the batteries in his transmitter were weak :-)
    
I was going to say that he went on oxygen a bit late 8^)

I'd be interested in the story. I'll bet the temperature drop was pretty
noteworthy (3 degrees/1000' as I recall)