wouldve made their lives easier if theyed invented JETS , save the pavement ;



this horrible creten looks like itd be quite straightforward , semi scale .
other than a Leadout thingo sticking out , and a extension drive to keep it mid engined,
with all the cooling ducts similar to F. S. . Cant see why itd need flaps . but does this mean
the AIRFOIL unflapped'd be not entirely related to a flapped ( F2B ) Airfoil .

looks fairly straightforward . 

Interesting video of the Kyushu J7W Shinden at



The prototype flew just before the end of the war.

An RC version by Col Bob Thacker appeared in Model Builder, August 1984, 62" span.

Keith

This is my Shinden, built from a classic Japanese kit (still in production by KMCo, in Japan), powered by OS CV15.
The performance is sooo poor because it is heavy, in addition it needs lots of nose weight.
Aki

Shinden drawings I saw showed a floating canard, which would have allowed the CG to go farther back. 

This thread brings back memories of VSC-III and Jim Renkar's canard "Can Stunt", a Paul Del Gatto design in FM.  Repeated attempts to break ground were, shall we say, "less than successful" - after which Jim borrowed a marker pen and wrote on the wing, re-naming it "Can'T Stunt".  Photo attached.

Many years ago I built a canard with forward wing rake. It flew well, except some hunting in level flight, but I never could tame the FOX 45…
It was destroyed because of a line connector failure. An electric version is planned.

Got a olde French magazine with THIS in it . a R/C ( two channel ? ) racer , for .049 to .015 . Flying foreplane .



foreplane airfoils about the same as the wing , maybe 10 % .
spans about 33 in ( to use 36 in. sheet / spars , presumeably )
fairly cunning contrivance , so may try it C/l to see what happens .
C.G. is shown a bout 2 in behind L.E. at fuse .

another sketch in the mag. shows a spacehoundish square canopy
thatd work as a good cowl , with a mid mounted FSR 25 and tank at C.G.
with slightly less slopeing rear deck .
A N.A.C.a. intake on top deck fwd. of canopy & open outlet aft should get the cooling airflow o.k.
Id use 48 odd for the FSR , ive got some 9x6 pusher props , and been looking for a ' light hack '
for the ball race 25 , so it looks like it might do it . And similar enough to the shinden for a info
cross over if it works . Good Excuse for a flying Tailplane too , though its a foreplane Im Told .

havnt searched through the French Site where I found the photo . Theres a few FAI T/R ships on that page ,
http://docmodeli.free.fr/rubriques/plans/index.php?pageNum_modeles=+++++++++++++++++++++++29&totalRows_modeles=3781&criteres
so theres a chance theres a few F2B ships on board too . ?

The reasoning was that the CP and the CG are too far apart on the normal configuration that is most often used. The model flies off of one or the other until a certain angle of attack is reached, and then it reverts to the other point.

    If it is flying in stable level flight, the CG and CP (of the entire airplane) has to be exactly on top of each other. If it is hunting (heh) up and down the CP is moving moving forward and aft of the CG. It can't "fly off of one or the other".

    I would propose that it is/was unstable at low AoA, probably because the CP moves aft at the AoA increased (and hence moves forward as the AoA goes down). Sweeping the wing forward helps by reducing the CP shift by effectively "shortening" the airplane.

   I see that you noticed the other issue - no flaps!

    Brett

I see that you noticed the other issue - no flaps!

As far as I can tell, flaps aren't useful because they help make the airplane turn a tighter corner (induced drag seems to be the limiting factor there), but rather because they can control what point the aircraft rotates around.

So I'm not sure how much flaps are really useful on a canard, or even which direction you'd want them to work -- I'd have to fly one or see one fly before I formed an opinion.

My canard experience is limited to an R/C glider, which was not successful (because I didn't know what I was doing).

I remember that Tommie Lay built a stunt canard, but I don't know how it went.  Does anyone have that info?

Floyd

Hi Floyd,

Tom seriously went to a lot of trouble to research that canard he build and flew (or tried to fly).  I could go back to find the names involved and where and how he came up with plans.  Supposedly, the model was built to plans that a person built either in the late 40's or more probbly, the early 50's, like around 50 or 51.  It was flown at the Nats, and there was a report that Geroge aldrich commented that it flew the tightest coners he had ever seen.  That was the inspiration the Tom used to learn more about the airplane.    I do not know where he found any plans.  Anyway, Tom built it.  I was with Tom when he first tried to fly it at Whittier Narrows.  As I remember, he was barely able to get it off of the ground after several tries.  Sometime later, he had changed the CG or something.  I think he brought to VSC one year.  But it would barely do a loop, if that.  Whatever was flown that George witnessed years ago was certainly not what Tom's plane was.

Ron van Putte´s article on canard CG worked for me.

Not necessarily.  I don't think it did on the Shinden.

I was trying to keep the discussion centered around things we might build to fly in circles with.

I would really like to know how the Shinden was put together.  It would seem that if it had a "floating" foreplane that was connected to the stick, the stability of the airplane would depend on the pilot not holding the stick rigidly -- if you got a pilot who grabbed the stick and locked their elbow, then suddenly the whole assembly would be unstable.

(I'm assuming that by "floating" you mean a foreplane that's pivoted well ahead of it's MAC, and which without pilot input just follows the slip-stream).

If you tried to build such a "floating" foreplane in a stunt ship, but connected it rigidly to a bellcrank, I suspect that it would act fairly rigid, no matter how the pilot held the handle, due to the action of drag and inertia on the flying lines.

Ron van Putte´s article on canard CG worked for me.

It's the usual simplification.  It doesn't quite provide the understanding one needs to get clues about how one could innovate.  I think experimentation would be more useful.

You let the main canard surface float and drive a tab on the back.  Better yet, you drive a stabilator behind the canard.  . 

   
   Oh. I didn't ever get that part in the previous thread.

    I still think, stability aside, you still want the wing cambered the right way in the corners and I haven't seen any good answers on how it winds up better than what we are currently doing.

A rotating cylinder would work, but it would be hard to change direction fast enough for the transition in eights.

    Until you hung it, then it goes over the left field fence.

   Brett

   

My suspicion is that it wouldn't be any better, if you could even make it as good.  If a canard configuration had so much potential then you'd think that at some point in the last 80 years that people have been flying control line, people would have figured it out and started flying them.

Unless you can do as Howard suggested once in some other thread, and use active stability augmentation together with a rearward CG.  Even then -- nah.

 Given the approach to date on just about everything else, it wouldn't surprise me to find that people missed something. I don't subscribe to the "if it was worth anything it would have been invented already" theory, particularly when most of stunt folklore is utter and complete nonsense.

   An example -  people had known about and fiddled with tuned pipes in stunt since the 60's (and I would have to check, but Wild Bill was talking about tuned pipes AND lower pitch props since before that). Until schneurle engines and the associated fantastic performance improvement, no one knew how to use it effectively. Everybody tried to boost the power and still run it at 8500 RPM. RC schneurle engines don't work worth a darn on a muffler. Bobby and company could only have figured out the *correct* way to use them after having attempted to tame schneurles on mufflers, then fly and an *RC Pattern Plane* with the engine set in an off-nominal way. And then be willing to actually try it.

  The fact that you or  I can't see how it would be an improvement (particular since the goal seems to be tighter cornering, which is not a limitation with the current airplanes anyway) could easily be just the way we are looking at it, and someone else can come along and figure it out.

   And in any case, thinking these problems through can be extremely helpful, even if it doesn't lead to a direct action.

   Brett

Guess ours was a little better than theirs...at least got off the ground more than once. 

Guess ours was a little better than theirs...at least got off the ground more than once. 

Yes, but cleaning the seat was such a chore for the ground crew, particularly after a foreplane stall event.

He may just have been commenting on the need for a higher lift coefficient on the foreplane to maintain stability.

I don't think he'd have said that, either.

What? again? Looks like canards need to be analyzed at least once yearly :- ))))

canard needs a higher CL than the main wing

that is clear and many times covered especially on SSW forum, but it is only about level flight, maneuvering in corners needs much more and situation is much worse

however that all are only guesses, it need to put 3 equation and solve them at once:

1/ we need lift in corner so we ned to count AoA, flaps and elevator deflection and airfoil properties and surface areas

2/ we need pitching moments, so we need lifts from surfaces as moments to AC plus surface airfoil momets plus CG moment

and all 3 AT ONCE

it makes relatively complicated situation, which will not allow simply decide that flaps on main surface will go down or up, we simply need to FIND where they must go to keep 1/ and 2/ conform. It will be immediately clear, that flap and elevator down to 30 degrees will make enough lift, but almost no pitching (so we cannot use that lift), and since CG is front of NP plus airfoil pitching moments, pitching will probably opposite then we need, so sooner or later we will find that rear surface needs smaller deflection than front surface ... clear solution will be to make wing smaller ... after several trials we will see that the optimal configuration is rear surface little over 25% of front surface :- ))) 

:- )))

Also piece of paper will do crisp corner, question is how to do it with usefull (= heavy) wing load and with proper (= small) radius.

If the foreplane gives more lift, simply do it larger, it will give even more lift ... guess where it leads :- ))

... do you know already what I wrote? :- )))

As we all know, the smallest radius is  r=2*m /( CL* A * rho).

Without flaps, the maximum CL of the wing is lower because of missing flaps, but the canard gives additional lift.That helps to reduce the radius

     Igor had it right before!

    Besides, even entirely conventional airplanes with average wing loading will still turn, or at least appear to turn, tighter then the pilot can deal with anyway. I have never attempted to fly to the physical limits of any of my "regular" airplanes in terms of corner radius, at least not in competition.

     Getting it to start and stop the corners abruptly is also a limitation you will likely hit before you hit the wing loading/Cl limit. That,  I do work on and trim for. Paul Walker is the absolute master of that particular art, and I (we) learned a lot from watching and analyzing that.

     Brett

   Next up for the winter "Hot Stove League", flying stabilizers.

Why not?

With or without servo tabs?

I'd do it without.  You can hinge the thing wherever you want, so servo tabs would: a), do the same thing as hinging the stab a little farther aft, and 2) would have more separated flow, the avoidance of which is probably the best reason for the stabilator.  One could have the tabs go the other way: to wit, the same direction as the stab.  Some Piper airplanes do this. 

and what about fixed elevator stunter? ... if classic (elevator back) design has flaps down and elevator up ... and canard (elevator front) has flaps down and elevator also down, then "something between" (some kind of tandem, or oversized tail design) must fly well with fixed elevator ... right?? :- ))) 

... so who comes first with elevator-less stunter???