stabilator for contrline stunt ship

[Lynn Weedman]

Does anyone have info/geometry/dimentions, ect. for a prooven stabilator design on a controline stunt ship?

[Bob Whitely]

There is no proven stabilator design for a stunt ship.  Why?  'Cause it has been tried and did not work then and it still won't work now.  RJ

[Lynn Weedman]

I read the threads on stabilators in the stunt design section. And it seems its application is suited more fore combat airplanes. Although, the Humbug is an interesting design using a stabilator. So the anomalies with this design are : hunting in level flight, over controlling when cornering, control resistance when returning to nutral. There should be a way to set up the geometry of the control system to correct these negative attributes. Any math wizards out there have any input?

[Scott Hartford]

Bill Wilsons NFP-1 has a flying stab that works just fine.....

[Wynn Robins]

So does Lawrie Crystals airplane he has been flying for the last 28 years - YEP 28 years and it still flies a VERY good pattern!!

[phil c]

To the gentleman's question,
1) figure out how you are going to hinge the stabilator.  The hinge has to be very free and not wear out quickly.  It probably isn't what you want, but I have used a stabilator with a sewn hinge on a 3 in. mini stab, which holds up well.  I used it Ringmaster style, with the hinge at the back of the fuselage.  If you want to put it through a full fuse I'd experiment first, using a carbon fiber or aluminum arrow through the fuse to join the two halves.  A second joiner at 50-75% chord would be a good idea.  If you go with some type of bushing or ballbearing for the hinge it would be a good idea to be able to take it apart for repairs and modifications, at least for the first one.  Perhaps the two guys who have seen a good, working setup could post pictures or sketches of the hinge?

2) A stabilator can be effective with an area as little as 10% of the wing,  but 15-20% is probably better.

3)  You have to work out the control loads.  Wild Bill Netzeband's old articles(1963-62 American Aircraft Modleler) have all the info and are available on line.  The hinge line needs to be no more than ~20% back from the leading edge.  IF you go as far back as 25% you'll end up with virutally no load on the controls and lose all feel for what the plane is doing.  With a 15-20% area stab you probably want the hinge to be the same percent back from the LE.  A 10% stab can work well hinged at the leading edge. 

4) fine tuning the balance point, control movement, and handle spacing takes more care than with a stab/elevator.  There is a sweet spot that gives smooth control, good corners, and good return to straight flight, but it seems to be smaller than a conventional tail.

[sleepy gomez]

Sorry Bob, just because I'm not a name flyer and can't even do the whole pattern doesn't mean I can't properly design a stabilator equipped plane.  I have five of them hanging in my shop right now.  Hinge it at the LE, have a tail volume coefficient of between .24 and .30, start with cg at 25 %.   Make the hinge using an aluminum tube (or brass) at least 3" long attached to the stab plate.  A wire is inserted into the tube.  The ends about 3/4" on each side are bent back at 90 degrees.  The wire is then inserted into the LE.  Good bearing surface and good stability.  A drop of fuel makes a forever lube.

[Bob Whitely]

Since I am the only Bob that posted then I would guess the last one was for me.  Sorry if you took it personally, it wasn't meant that way.  It is just that this has been  tried many times before and for competitive stunt purposes just will not work. One that comes to mind was built by Dave Fitsgeralds' father.  It was an extremely nice model and was as good as it gets but with a stabilator.  He told me that it flew well but not great. If a stabilator was the answer to a better flying plane, trust me, there would be a lot more of them.  I have no doubt that you can figure out all the parameters needed to make one work just not good enough to be competitive.  As for sport flying by all means build to your hearts content and have fun...RJ

[Kim Mortimore]

Speaking of sport flying (to avoid the controversy here), I see one plane after another that has uneven inside/outside turn rates, many built by pretty decent builders from what I can tell.  It's no so easy to adjust.  Sometimes the famous lowered elevators at neutral works and sometimes not, depending in part on which direction has the faster turn rate.  I'm curious if one advantage of a stabilitor might be it's self-adjusting neutral.  You can't build in bad stab incidence if you ain't got no stab  .  (This assumes correct thrustline of course).  Or maybe a stabilitor would not help equalize turn rates.  Anyone have experience with this?   

[Trostle]

I will add my thoughts here which coincide with what Bob Whitely has already said on this forum and has been explained over the years on this and other forums.  Yes, a stunt ship can be designed with an all flying stab that can be flown through a presentable pattern.  In fact, the information that Phil Cartier has already mentioned in this thread is useful information to obtain a model that will probably "work just fine" or even "fly a good pattern" for the next 28 years.  Combat designs have used stabilators for years. 

I think the message that is being lost here is that indeed, there has been a good number of top stunt fliers who, over the years, have tried stabilators on their models.  The general consensus of all the top pilots who have tried these things is that the performance is less than satisfactory.  If it was a great benefit to the performance of the models, then top pilots would be using the idea.  I doubt that you will find any stabilators on any top 10 or even top 20 finishers in the Open event at the Nats for the past 30 or 40 years.  We have yet to see any of these models that "fly a good pattern" or that "work just fine" in the top echelons of major competition.

I am not trying to put down those individuals who do fly well at the local level.  It is just that there is a large difference in what is seen at the local level and the top level of competition in our major competitions.  And stabilators Will not provide that leap forward to top level competitiveness.

Sure, there are good pilots that can fly "presentable patterns" with whatever, but stabilator quipped designs will not help anyone win the Nats.  Have fun trying to get them to work.  You might find something worthwhile where nowbody else has.

Keith

[john e. holliday]

Even Bob Baron went to stab/elevator set up on the later Humbug.  Do you think the Humbug was too unusual to score well?  I know he finally won a NATS with his version of the PatternMaster.   

[Jim Pollock]

Gee Now,

Has a stabilator every won the Nats.......well, heavens yes!  the year 1949, the great Bob Dailey won the Nats with a plane that had a stabilator hinged at the 33% mark, his flying buddy  Sam Dehelean, had an identical model hinged at 47%, now in those days they flew a good bit faster than we do now, so maybe that had something to do with them performing the pattern well at that time.

Jim Pollock      

[Trostle]

Gee Now,

Has a stabilator every won the Nats.......well, heavens yes!  the year 1949, the great Bob Dailey won the Nats with a plane that had a stabilator hinged at the 33% mark, his flying buddy  Sam Dehelean, had an identical model hinged at 47%, now in those days they flew a good bit faster than we do now, so maybe that had something to do with them performing the pattern well at that time.

Jim Pollock      

Let's see now.  If we are getting technical, I cannot argue about what the airplane was that won in 1949.  That would have been 61 years ago.  And there were significant differences in the pattern in those days when "precision" was not part of the event name.  I did not say nor question if the stabilator equipped airplane "every won the Nats".  My statement was that I doubted any stabilator would be found on any top 10 or even top 20 finishers in the Open [Precision Aerobatics] Nats event for the past 30 or 40 years.

Even if there is a lone chance that such a model could be found from the past, the point is that if there is some yet to be found advantage, howver miniscule that advantage, to these things, we would see them at the top levels of competition.  It has been found, so far, that there is NO advantage to these things.  If anything, they are a disadvantage.  Therefore, we do not see them being used for serious competition.

This certainly should not deter anyone from trying out the concept (as many have already done).  Who knows, there just might be the chance that a combination of design features not yet explored that just might be a key to really make these things work to our advantage.  Experimenters are welcome and hopefully, they will share their results, whether favorable or not.  If they work, it will take more than statements that it will "fly a good pattern" for whaever period of time or that they "work just fine".   (Those statements are like saying the Sterling Yak will fly well as has been claimed on these forums in the past by those who have never flown a complete pattern.  Our frame of reference regarding the merits of stabilators needs to be in the context of being able to fly a competitive pattern against top levels of competition.)  There needs to be a contest record to go along with those statements against solid National level competition.  And it does not need to be done by a "name" or "elite" flier.

Keith

[Brett Buck]

It has been found, so far, that there is NO advantage to these things.  If anything, they are a disadvantage.  Therefore, we do not see them being used for serious competition.

     Put a different way, a flying stab doesn't solve any known problem.

     Brett

[Scott Hartford]

What are the disadvantages?

[Brett Buck]

What are the disadvantages?

   Heavy mechanism, and generally weak. The axle takes the entire load of the stab, so it has to be very tough, and it's also very difficult to make the pivot with no free play but still free to move easily. Everything has to be beefed up to take the load, and transfer it to the rest of the airplane , so it's very heavy right where you can least tolerate it. All of this for a microscopic theoretical advantage in drag, and very dubious value or even a disadvantage in any other area.

     Brett

[Trostle]

   Heavy mechanism, and generally weak. The axle takes the entire load of the stab, so it has to be very tough, and it's also very difficult to make the pivot with no free play but still free to move easily. Everything has to be beefed up to take the load, and transfer it to the rest of the airplane , so it's very heavy right where you can least tolerate it. All of this for a microscopic theoretical advantage in drag, and very dubious value or even a disadvantage in any other area.

     Brett

I agree with everything that Brett says here.

Also, in general terms, they do not groove as well and it is more difficult to precisely stop a turn (as in the square and triangular maneuvers).  A degree of precision is lost when flying with the all flying stab.  And the event is still called and judged as Precision Aerobatics.  (Conversely, this degree of precision is of little cnsequence when flying stabilator equipped combat ships where speed and low drag are significant factors.)

As Brett suggests, there may be a slight reduction in overall drag because you can use a smaller horizontal tail.  However, low drag or reducing drag on a stunt ship is not a paramount requirement.  More than half of the drag of our line/plane system comes from the lines.  A slight reduction in the drag from the horizontal tail and any reduced drag from the deflection of the horizontal tail will have little or no effect on the performance of the airplane to perform the stunt pattern.

Keith

[billbyles]

(Those statements are like saying the Sterling Yak will fly well as has been claimed on these forums in the past by those who have never flown a complete pattern.)  
Keith

 
Whoa, Keith...easy on the Yak-9!  Just because I've gone easy on you for the past few years by not flying my Yak-9 doesn't mean it isn't a great flying airplane.  Why, it will do the entire OTS pattern (as long as the wind is not over 5kts), and it will do the whole AMA pattern despite the claims of some who say that the hourglass represents a mere squiggle in the sky.  Not only that but it is powered by the venerable Fox .35 turning a high-tech Y&O 10-6 prop with only a few nicks in the leading edges.  OK, that does it - now I'm going to fly it at the VSC next year...look out Big Jobs, Jamisons, Humongous(es, i, s'?), etc.  I may even cheat and put a practice flight or two between now & then!  Not to mention some high-tech upgrades such as new wheels and possibly a new Top Flight 10-6 prop.

[Lynn Weedman]

Thanks for the input gentlemen,
The results of the question I asked about stabilators were basically the same as I had already determined in my designing efforts. There clearly isn't enough advantage gained by using this configuration and the weight is a big issue at this fuselage station on the aircraft. I suppose I'll just use the standard issue stab & elevator set up.
Lynn Weedman VP X47 Flyers   

[Air Ministry .]

It would appear that characteristics are due to airfoil and aspect ratio , for aerobatics.

An airfoil mimicing the wing section would have similar behaveior.

Lower A/R is apparently nessesary (than wing) to prevent premature stall.

A Carbon Tube spar should alleviate any structural concerns.

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A spar pivoting in ply doublers may be adequate . More ridgidity would be found

by having a fixed spar and bushed stabilators, which would make the rotateing

mechanism awkward. Though a yolk though both sides at (under) the hinge , or

fwd of the hinge though curved slots (see a F4 phantom) should provide adequate

structural integredy at a resonable / comparable weight to a conventional stab/elevator assy.

-------------------------------------------------------------------------------------------------------

Hawkers Tempest initially hat tail plane stalling issues, being a carry over from the Typhoon.

Once the section / airfoil was changed to be comparable to the wing section ,(speed range)

The landing behavior was satisfactory. - No stalled rear horizontal stab . which makes control

evasive.

[Juan Valentin]

Hello X47
              In the 1964 March Issue of Model Airplane News there is a design by Jean Pailet of the Pegasus that has a flying stab. I read that he cut the booms and used the wing on a design called the Zephyr because he was not pleased by the way it flew. No mention on what was the problem with it. I looked at the plans and noticed that the stabilator was powered by end of the flap which made me think that maybe the flap was twisting and as others have mentioned coming out of a corner and getting it on a straight path might have been difficult. I like the model but if I build one it would have a fixed stab and use an elevator and the pushrod would come out from the flap horn directly to the elevator horn which I would place in the center of the elevator. I know it wouldn`t be aestetically pleasing or correct for contest flying.Here is a pic of the plane areally nice looking job.
                                                                                                                                      Juan

[Jim Pollock]

Hello Keith,

Yup exactly as you say 1949 they flew a totally different pattern and in a completely different way.  So, I do agree with what you say about stabilators in present day terms!  Don't even think about it!

Jim Pollock   

[Brett Buck]

Thanks for the input gentlemen,
The results of the question I asked about stabilators were basically the same as I had already determined in my designing efforts. There clearly isn't enough advantage gained by using this configuration and the weight is a big issue at this fuselage station on the aircraft. I suppose I'll just use the standard issue stab & elevator set up.
Lynn Weedman VP X47 Flyers   

    It's an interesting idea and it comes up periodically. Most of the improvements we make are the result of identifying issues and trying to fix them, much more than coming up with breakthrough ideas. In this case it's been thoroughly experimented with and really didn't offer any improvements. But it's a reasonable question to ask.

     Brett