Doctor and Medic -- Past and Future

[Larry Fulwider]

One of the more interesting designs ever published is Ted Fancher’s Doctor (and little brother Medic). The accompanying article in Stunt News was equally interesting.
   The concept (and advantages) of a simple flapless profile stunter, designed using state-of-the art design techniques, that was easy to trim but capable of earning as many points as its more sophisticated brethren was a bold one. Many were built, and everyone thought they were great.
   The designs have broad appeal to retreads, wannabes, sport flyers, and perhaps even serious competitors up through Advanced.

A fairly easy build (looks like), with the exception of the tedious spar cutting of the ribs. However, with laser cut ribs, it would be a lot easier.

Anyone have any Medic or Doctor  pics they can post?

I was thinking, if there were any up-and-coming low production kit companies, that specialized in laser cut ribs, hand cut fuselages and tailplanes, and were looking for new designs to kit, well the Medic or Doctor  just might be a perfect project for them. Know of any such companies? 

I’d sure buy either kit a heartbeat!

      Larry Fulwider

[Larry Fulwider]

Page 2 of Article

[Serge_Krauss]

Larry-

We were just discussing the "Doctor" last night at the NCCL club banquet. Nelson Erbs said that his seemed very touchy on c.g. placement, being an "OK" stunter before, but becoming excellent with a quick but solid turn, when he felt he had gotten the c.g. right (which I take it was quite recently).

This, I believe is Nelson's version, taken 7/22/08.

Edit 2/4/10: Oh, Boy! Now I've done it. Nelson says it's a "Medic", not a "Doctor", and apparently my description was none too accurate either. She-e-e-esh.  So far I've done much better as newsletter editor and chief reporter than I have here. I'll post the rest separately below.

[builditright]

One of the more interesting designs ever published is Ted Fancher’s Doctor (and little brother Medic). The accompanying article in Stunt News was equally interesting.
 The concept (and advantages) of a simple flapless profile stunter, designed using state-of-the art design techniques, that was easy to trim but capable of earning as many points as its more sophisticated brethren was a bold one. Many were built, and everyone thought they were great.
 The designs have broad appeal to retreads, wannabes, sport flyers, and perhaps even serious competitors up through Advanced.

A fairly easy build (looks like), with the exception of the tedious spar cutting of the ribs. However, with laser cut ribs, it would be a lot easier.

Anyone have any Medic or Doctor  pics they can post?

I was thinking, if there were any up-and-coming low production kit companies, that specialized in laser cut ribs, hand cut fuselages and tailplanes, and were looking for new designs to kit, well the Medic or Doctor  just might be a perfect project for them. Know of any such companies?  

I’d sure buy either kit a heartbeat!

  Larry Fulwider

What's that ole saying..  ye ask and ye shall receive, seek and you shall find... that said, a little over a week ago
 Ted and Pampa gave me the green light to make kits of the Dr and Medic, I am just waiting for the plans to arrive
from Jim Snelson so I can send them off to Ted for any corrections and then we will start the cad drawings. I was
planning on making an announcement after the wheels had been in motion, but you forced me into opening the bottle
before it's time, so please forgive me; I didn't mean to hijack your post with the announcement that I am planning to
make kits of the Dr and Medic. In addition, Ted also gave me the okay to make his Fancherized Twister and those plans
are almost done, will make a separate post.      






pictures will be appreciated

[Brett Buck]

We were just discussing the "Doctor" last night at the NCCL club banquet. Nelson Erbs said that his seemed very touchy on c.g. placement, being an "OK" stunter before, but becoming excellent with a quick but solid turn, when he felt he had gotten the c.g. right (which I take it was quite recently).

   Ted will certainly chime in when he has a chance, but I have flown the original "Doctor" quite a few times, and that observation surprises me. The only thing unusual/different I noticed about the control feel was that the control response appeared to vary noticeably with airspeed. Both airplanes, and as far as I can tell, all elevator-only airplanes, greatly benefit from a very constant airspeed/power propulsion. Low pitch/high rev REALLY reduces the control sensitivity issues. Unless the CG was very near the aft limit I would be very surprised if small CG changes had a big effect. We flew it with the CG all over the place and didn't really notice any big changes. i don't dispute the observation, of course, if that's what it did, that's what it did.

     Between the two airplanes (Doctor and Medic) I thought that once we got the one Medic we had locally trimmed*, it was probably the better flier overall. The original Doctor is so large and light that it's like flying a kite in any sort of wind. The published plans might be smaller than the original model to solve some of that, but the Medic seemed a lot more solid on the ends of the lines and didn't float around as much. Both turn so much better than they need to and the airfoil is superior to all the similar models that the wing loading is just a complete non-issue as far as performance goes. And it might have been the engine - the Medic had a 25FP/9-4, which was perfect for the model. I don't know if the Doctor had the perfect power selection. Maybe with another 6-8 oz on the Doctor would have solved the issue  - although this isn't at all like the ballasted-up Tucker Special experiment, because in no case did the Doctor get close to running out of control authority. Both had the "fingertip" control response and turned exactly where and when you expected, instead of a sort of delayed turn you get with some flapped models (and mentioned by Bill Netzeband decades ago).

      Brett

*http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=2609&mesg_id=2609

[Ted Fancher]

Well, since Brett more or less broached the subject, here's a couple of thoughts on the original Doctor versus the PAMPA plans versus the nascent Umland kit.  I must preface these remarks with the comment that the original airplane has flown numerous 500 plus point competitive flights using a variety of powerplants.  It is a sound design and the comments about flaps included in the original article are still golden in my estimation.  Nonetheless, subsequent revisions to the design make it better and the Umland kit should be pretty close to as good as a simple flapless ship can be.  Here are the comments I'll be passing on to Walt and Bob Kruger (who'll be drawing the CAD plans which will also provide the digital data for cutting parts as I understand it).

Brett's comments about the original have merit (as you'd expect, since he's flown it a number of times).  First of all, the airplane was bigger than necessary (in part because of the merits of an airfoil that permits higher angles of attack thus achieving the necessary lift without the need for excessive amounts of wing area), second of all because (as part of the design plan to make it as easy as possible for newbies to put together) it used a commercially available three inch bellcrank.  When combined with the large area tail and its 50/50 stab/elevator configuration and the light wing loading the Netzeband wall became a very real consideration when trimming it out.

The first iteration of those fixes was to shrink the size of the PAMPA plans version to something more reasonable (don't ask me exactly how much, I'm a lousy record keeper and have neither the original plans or a copy of the PAMPA plans readily available).  The only version of the airplane that will exhibit the characteristics Brett discusses was the original since no others were built with those specifications.  The smaller area and the use of a four inch bellcrank and a long tail horn eliminate any concerns about adequate line tension to allow full control capability under any usable wing loading and airspeed.

This, by the way, is one of the primary reasons why the Medics seemed more comfortable in terms of consistency of inputs for a desired rate of turn.  The Medic is significantly smaller than the Doctor yet used the same three inch bellcrank.  The Netzeband wall was pretty much a non issue as a result.

Additional changes will be suggested for the Umland kit.  These will largely be modifications to the tail configuration.  First, the original tail was bigger than necessary for an unflapped ship because the tail doesn't have to overcome the negative pitching moment of the flaps before it can pitch the aircraft in the desired direction.  My suggestion will be to reduce the total tail area to about 18 to 20% of the wing area and to relocate the hinge line so that the stab/elevator chords (and, therefore, areas) will be 60/40 versus the original's 50/50.  This will further decrease "hinge loading" (the amount of torque necessary to deflect the elevator surface against the airflow.  The lower the aspect ratio (span/chord) of a deflected surface of a given area the more force is required to deflect it...and the less efficient it will be.  It might be important to remind readers that it is the entire surface (stab and elevator) that produces the lift that changes the pitch attitude--not just the "flipper".  An "efficient" distribution of area between the fixed and deflected portions of the tail is what matters, not just the size of the "flipper".

Just a couple more words to reinforce my confidence in the value of eliminating the flaps to simplify trimming the airplane to its ultimate level of performance.  Always remember that the primary thing flaps do is increase the lift a wing of a given area can produce.  The lift that might be lost by eliminating the flaps can be recouped elsewhere: larger area, a higher critical angle of attack (the reason for the blunt leading edge and forward high point of the airfoil), or a modestly higher airspeed (lift goes up as the square of airspeed).  Ergo, all the lift that is necessary for a competitive pattern under most conditions can be produced without flaps.

The benefits for anything other than competition in the upper levels of Advanced or Expert is that an airplane without flaps is monumentally easier to trim to its optimum performance.  I encourage you to read the article on the Doctor/Medic for an in depth discussion of why that is so.  Hopefully, someone will be able to scan and post the balance of the article which is where the meat of the discussion can be found.

Ted Fancher

[Jim Thomerson]

A late friend, Jim Wilson, built a small Doctor for a PAW 09, I watched him fly it in winds where the rest of us had put our airplanes away.  He flew lots of maneuvers, all with 1 ft pullouts.   After flying, he commented, "That Ted Fancher knows something."

[Serge_Krauss]

Edit: Please see my later post (it's a 'Medic' anyway, and I 'remembered' wrong). I'm too tired to be embarassed, but annoyed with myself,...hmmm...

The term "touchy" probably was not an accurate translation of what Nelson said. So let me rephrase; I understood(?) him to say that his was "OK" but not great until he found what he termed the "right" c.g., where he felt the plane (suddenly?) flew markedly better. He may well have not had the ideal engine combination (steady speed) for it - I don't remember. He characterized his final results as very quick turns with solid recovery without bobbles. He was very happy with it. Maybe I can get him to comment further and clarify anything I might have misunderstood. I'll e-mail him.

SK

[Dalton Hammett]

*****************************
   I remember watching someone fly a Medic at Brodaks.   The plane seemed very smooth and looked very good,  enough to prompt me to find out more about it, who designed it and where plans could be obtained.   I have it on my bucket list of planes I'd like to build yet -- fortunately, toward the top of the list. 

WALTER  -- Thats good news,  I'll watch for your formal announcement !!!!!!

Dalton H.

[Larry Fulwider]

. . .
 . . .  Hopefully, someone will be able to scan and post the balance of the article which is where the meat of the discussion can be found.

Ted Fancher

There are eight additional text pages (definitely worthwhile, too!). Unfortunately, my little scanner, set to produce the smallest file (not the best quality) gives a file size for each page > 900 K. I ran them through Paint, and got them down to a fuzz over 500K per page. I haven't found a way to get them under 500K. With the 1000 k limit per post, that is 8 posts.
        I certainly don't mind doing that, but surely someone has a better idea?

       Larry Fulwider

[EddyR]

Larry  Scan them large and sharp then use PhotoFiltre free compression software. You can pick the dimensions  and then compress it to any size you want. It has a preview to see the size before finishing it. Make a file on your desktop and send all files from PhotoFiltre there. Once you have learned the steps you can do the complete process in 30 seconds. The learning curve will take a couple of hours. I can talk you through it on the phone one you have it set up.
Ed

[George]

A quick question for Ted: Have you made any changes to the Medic?

George

[Bob Kruger]

There are eight additional text pages (definitely worthwhile, too!). Unfortunately, my little scanner, set to produce the smallest file (not the best quality) gives a file size for each page > 900 K. I ran them through Paint, and got them down to a fuzz over 500K per page. I haven't found a way to get them under 500K. With the 1000 k limit per post, that is 8 posts.
        I certainly don't mind doing that, but surely someone has a better idea?

       Larry Fulwider

Larry;

If folks here can wait an hour or two, I will have the document scanned and available for download in Adobe PDF format.

V/r

Bob Kruger

[Larry Fulwider]

Larry;

If folks here can wait an hour or two, I will have the document scanned and available for download in Adobe PDF format.

V/r

Bob Kruger

Great! I was just doing some quality checks on some test scans. I have a technical problem, though.

Some of the pages need ironing.

We'll wait for your PDFs! Thanks 

       Larry Fulwider

[Bob Kruger]

Great! I was just doing some quality checks on some test scans. I have a technical problem, though.

Some of the pages need ironing.

We'll wait for your PDFs! Thanks  

       Larry Fulwider

All;

I wish the quality was better, but my scanner is somewhat limited.  I will try to improve the quality over the next couple of weeks.

Regardless, Ted Fancher's "Doctor" article is available for download from the PAMPA web site.  And, you don't have to be a member to download.

To access it, got to http://www.control-line.org/DesktopDefault.aspx?tabid=22

Scroll down to "General Articles".

It will be the first article listed.

And, for those who are not PAMPA members who like what they see, consider joining PAMPA.  For a basic $25 a year membership, there is full internet access to "Stunt News" with six new issues each year plus archives for the past four years.  You also have options for a CD version as well as a printed copy.  Additionally, we will be scanning in older issues as well.   Great people, great articles, great information, great hobby.

For those who want to build the Doctor and/or the Medic, the results of Walt Umland's efforts will be worth the wait.

Enjoy.

V/r

Bob Kruger

[Serge_Krauss]

Bob-

Nice work. I agree!

Edit: 'forgot to mention that I've looked forward to reading this article for a long time. Thanks!

All-

Well, apparently I wasn't listening - or remembering - that well. As I noted above in a correction to my original post, Nelson Erbs' model is not the "Doctor"; it too is a "Medic". I had sent him the full texts of posts on this thread up to the time of writing, and in his e-mail reply, he basically contradicts some of what I said. So I'll just relate his present description:

"Hello Serge,
 
"I just want to say that it's a Medic not a Doctor,...it is very stable and it goes where you point it. It's got an LA .25 now with a 9-4 prop, and that's about perfect. - Nelson"

So, contrary to what I said, turn was not his focus, and other things make him happy. Well, the Martinis at the NCCL banquet were good...

SK

[Brett Buck]

The benefits for anything other than competition in the upper levels of Advanced or Expert is that an airplane without flaps is monumentally easier to trim to its optimum performance. 

   95% of a "95% airplane" is a lot better than 75% of a "100% airplane".

     Brett

       

[Larry Fulwider]

 . . .

Additional changes will be suggested for the Umland kit.  These will largely be modifications to the tail configuration.  First, the original tail was bigger than necessary for an unflapped ship because the tail doesn't have to overcome the negative pitching moment of the flaps before it can pitch the aircraft in the desired direction.  My suggestion will be to reduce the total tail area to about 18 to 20% of the wing area and to relocate the hinge line so that the stab/elevator chords (and, therefore, areas) will be 60/40 versus the original's 50/50.  This will further decrease "hinge loading" (the amount of torque necessary to deflect the elevator surface against the airflow.  The lower the aspect ratio (span/chord) of a deflected surface of a given area the more force is required to deflect it...and the less efficient it will be.  It might be important to remind readers that it is the entire surface (stab and elevator) that produces the lift that changes the pitch attitude--not just the "flipper".  An "efficient" distribution of area between the fixed and deflected portions of the tail is what matters, not just the size of the "flipper". . . .

. . .

Ted Fancher

You and Brett have had similar informative discussions on the Doctor / Medic on other forums in the past. The difference I remember is that you were more reluctant to change total tailplane area (leave it at ~ 22%) [Edit: It was bad memory] and focus entirely on the split (60/40 or so) – to reduce elevator area for all the sound reasons described above, but treat the additional stabilizer area as a bonus. New thinking or bad memory?
   I also remember discussions of nose length, but not the details. Stock (heavier) mufflers are probably more common now than when you designed the Doctor. Is nose length (wing shifted forward, or ??) one of the additional Umland changes? Wing shifted forward is the one I seem to vaguely remember, but not the reason why.

Larry Fulwider

[Alan Hahn]

You and Brett have had similar informative discussions on the Doctor / Medic on other forums in the past. The difference I remember is that you were more reluctant to change total tailplane area (leave it at ~ 22%) and focus entirely on the split (60/40 or so) – to reduce elevator area for all the sound reasons described above, but treat the additional stabilizer area as a bonus. New thinking or bad memory?
   I also remember discussions of nose length, but not the details. Stock (heavier) mufflers are probably more common now than when you designed the Doctor. Is nose length (wing shifted forward, or ??) one of the additional Umland changes? Wing shifted forward is the one I seem to vaguely remember, but not the reason why.

Larry Fulwider

For some reason (probably because of all the "legal" issues in Old Time, Classic, and probably P30), I am imagining a CD in 2030 trying to figure out if a contestant's Doctor is 2nd Millennium (the design) or 3rd Millennium (the kit) legal!

Better save all the lunchroom napkins with the variations pencilled in (and signed by the designer).

[Dennis Adamisin]

Thanks Bob K for posting the .pdf link.  Thanks to Ted & Brett for the background info

...and you knew this was coming:
As I read the article I kept thinking what a GREAT electric it would make, the front fuse is thick enough to HIDE a battery internally, and a governor would certainly help eliminate any lingering remnants of "wind-up" behavior.  Of course I would also suggest that the simplicity of setting up electric power systems meshes (i.e., pick a prop then set the RPM) nicely with the underlying concept of the Doctor & Medic

(I'm SOOO predictable)

[john e. holliday]

You think most of us will be around then?  That is 20 years and I am approaching 70 too fast.   

[Alan Hahn]

You think most of us will be around then?  That is 20 years and I am approaching 70 too fast.   

Well the other possibility isn't quite as much fun I think! ----as long as I can still fly that is!

[Ted Fancher]

A quick question for Ted: Have you made any changes to the Medic?

George

Hi George,

The Medic was nothing more than a photographically reduced version of the Doctor (in fact, the Doctor as published was nominally reduced in size from the original as I mentioned in the earlier post).  I'll be amending the plans for the Doctor for Walt and those changes will be transposed to the Medic as there is aerodynamically no reason for them to be significantly different.  The biggest difference I will recommend is that the Doctor should utilize a four inch bellcrank and the Medic will do fine with a three incher.  Actually, with the revisions the Doctor would probably get by just fine with a three incher as well but there are definite overall advantages to larger control systems for anything other than moderate sized and smaller ships.  More "muscle" for a given amount of line tension.

Ted

[Kim Mortimore]

Ted,

Terrific article (as usual).  You do a great job of making the aerodynamics comprehensible to the rest of us, especially if we stick with it and keep reading you over time.  Questions:

As you mention, untapered wings tend to be more warp-prone, as do lightly built wings.  Brett has mentioned elsewhere that tapered wings are more stable, even with only a small amount of taper.

1.  Since Brett was likely talking about flapped wings, does this statement about wing taper also apply to unflapped wings?

2.  If so, is there any chance we might see a tapered-wing version, possible called the Nurse, as it would be a bit more shapely.   

3.  Also if so, if someone wanted to attempt building a Nurse with a minimum of design change, by increasing the root cord, say, 1" and decreasing the tip cord 1", keeping the same 18.5% airfoil throughout, do you think this could be done without "upsetting the applecart" of trim and having to go back to square one?   

4.  Stab incidence has been the subject of much discussion, typically with reference to flapped planes.  Would you say that stab incidence is not required on unflapped planes?  And briefly (by your standards  ) why?

5.  Same question for downthrust.

Brett, any thoughts would be appreciated as well.

Thanks,
Kim Mortimore

[Ted Fancher]

Ted,

Terrific article (as usual).  You do a great job of making the aerodynamics comprehensible to the rest of us, especially if we stick with it and keep reading you over time. 

Thanks, Kim.  Does that comment mean you hadn't read the article when it was published?  I ask the question because I've often thought that SN would be wise to consider republishing particularly helpful articles periodically.  I even at one time thought that a collection of such articles in a bound volume would be a great seller for PAMPA Products.  Don't know what the legal implications would be regarding copyrights, etc. though.

Questions:

As you mention, untapered wings tend to be more warp-prone, as do lightly built wings.  Brett has mentioned elsewhere that tapered wings are more stable, even with only a small amount of taper.

Oh, I think that's more or less the conventional wisdom although my experience with control liners doesn't really bear it out.  I know that a swept wing (an aft swept quarter chord, now, not just a tapered wing) has some dihedral effect which would benefit in the roll axis for an untethered ship but that wouldn't be of much help for a control line ship.  I think what Brett may have been referring to is more resistance to rolling from turbulence, cross winds, etc. because the area of a tapered wing is concentrated closer to the roll axis and, thus, upsets from external factors are probably mitigated by a tapered planform.  Again, for a stunt ship--which needs area but that can be compromised by low reynolds numbers at the tips if the wing is tapered enough to be meaningful--the benefits are probably small enough to be in the noise factor.  I've flown some awfully good constant chord (or nearly so) stunt ships such as the Chief.

1.  Since Brett was likely talking about flapped wings, does this statement about wing taper also apply to unflapped wings?

With the above caveats and remembering that the effect will be based on the quarter chord sweep which precludes gaining any advantage from a Cosmic Wind type of taper all in the trailing edge.

2.  If so, is there any chance we might see a tapered-wing version, possible called the Nurse, as it would be a bit more shapely.   

Believe it or not, at the time I was working with the Doctor I had given some thought to persuing a competitive version which would have included a tapered wing and tail--although primarily for aesthetics (see the above comments).  That was yet another "future project" that seems to have fallen off the shelf of stuff to do.  Too much involved in my newest "passion" for the time being and there just isn't enough time in the day.  Anybody else notice that as we "mature" it becomes more important to do the "other" things that you put off for most of your lifetime?


3.  Also if so, if someone wanted to attempt building a Nurse with a minimum of design change, by increasing the root cord, say, 1" and decreasing the tip cord 1", keeping the same 18.5% airfoil throughout, do you think this could be done without "upsetting the applecart" of trim and having to go back to square one? 

Yes, if done properly with respect to the above remarks.  I would make at least 50% of the taper in the leading edge (which would keep the quarter chord straight) and probably lean toward more leading edge sweep than trailing edge.  Again, I don't think it is a great big deal but if I was going to taper a wing while still searching for optimum performance I would cover my a$$ on the subject. 

4.  Stab incidence has been the subject of much discussion, typically with reference to flapped planes.  Would you say that stab incidence is not required on unflapped planes?  And briefly (by your standards  ) why?

That is an absolutely super question and one that bugged me a bit with the Doctor when trimming it out.  I kept wanting a bit more aggressive outside turn to balance the performance and (as you would suspect) drooping the elevator did nothing but change the handle position at neutral.  Without the flaps to "work" against you don't change the incidence relative to wing by fiddling with the elevator position.  Stab incidence, on the other hand, would be effective inj this regard.

5.  Same question for downthrust.

Because I'm of the opinion that downthrust and positive incidence are both at war against the same enemy (precession and P-factor) I think some downthrust in the Doctor would be a good idea.  I've never built a ship with "on purpose" positive incidence just because I'm afraid of the results if the amount used turns out to be excessive or--for some reason--counterproductive.  I think you can put a lot of down thrust in an engine before it will start to generate any difference in turn response.  Thus, downthrust would be my choice for dealing with these forces.

Brett, any thoughts would be appreciated as well.

Thanks,
Kim Mortimore

[Larry Fulwider]

 . . .
 . . .  I am planning to
make kits of the Dr and Medic.   

. . .

Walter --

Any schedule for availability? Is this a 2010 offering?

        Larry Fulwider

[Kim Mortimore]

Ted,

THE DOCTOR ARTICLE.  The article was published before I became a retread, although I had read it a couple of times previously before this current discussion.  I think how much a reader gets out of the theoretical side of an article or a message board post depends on his level of experience--how prepared he is to understand it, and that repeat reading of more difficult material over time is rewarded by increased understanding.   I just now reread Brett's discussion of trimming the Medic at: 

*http://www.clstunt.com/htdocs/dc/dcboard.php?az=show_topic&forum=103&topic_id=2609&mesg_id=2609

...and now I'm thinking SHEESH--major effects on the roll axis caused by a small change in rudder offset!   I may never understand all this completely, but I keep plugging away at it, which brings us to....

REPUBLISHING ARTICLES.  Personally, I have always thought it was unfortunate that all this information about stunt gets published in such ephemeral forms as magazine articles and web posts.  It would be great to see a magnum opus entitled "THE STUNT BIBLE" by Brett Buck.  Brett could then attach a large target to his forehead and pass around the guns 'n ammo.      A printed collection of key articles would be great.  (Old guys like us still think in terms of paper).  Since this is the 21st century, and electronic collection would be another way to do.  Simply adding more articles to the PAMPA website for download, reading, and printing if desired, might be easiest.     

NEW PASSIONS.  "Anybody else notice that as we "mature" it becomes more important to do the "other" things that you put off for most of your lifetime?" --Ted.    Yes.  That was easy.     So may fun things to do, so little time.

STAB INCIDENCE.  "I kept wanting a bit more aggressive outside turn to balance the performance..." --Ted.  Are you saying that the Doctor turned tighter inside than outside?  If the plane had a triangular nylon horn, which would be easier to adjust than a steel horn attached to the joiner wire, and you moved the horn aft a bit and lengthened the pushrod accordingly, so that the bellcrank and elevator maintain correct neutral alignment, but the controls are slighly biased toward Down, would you see this as a "legitimate" approach to balancing turn rates, similar to stab incidence and downthrust, or would it be a "band aid" fix as you have described asymmetrical Up/Down line spacings at the handle?

DOWNTHRUST.  Your response to this question is completely eye-opening to me.  This is great.  Windy clamp-mounts anyone?   

Next topic of interest:  OUT-THRUST/ENGINE OFFSET on flapless planes.  Later.

Thanks a million,   
Kim 


 

[builditright]

Walter --

Any schedule for availability? Is this a 2010 offering?

        Larry Fulwider

If we can get some interest on them, then yes we're planning for sometime this year

[rustler]

The last thing I need is another model on my "Must Build" list. However, these posts do arouse my interest greatly, and Ted's comment about what engine you have lying around hits the mark. Recently I couldn't resist buying a cheapo 2nd. hand engine in my LHS, (the famous 308/HJN store, Holloway Rd.), an SC36!
Ted advises against "improving" with L.E. sheeting etc, because you'd lose the turbulator effect of the spars. I'm a great believer in "D" boxes. What about a "D" box wing with e.g. cotton thread or 1/32 wide trim strip for turbulators at the same place as the spars?

[Kim Mortimore]

Ian,

Just out of curiosity, what was the cheapo 2nd. hand engine you found at the LHS?

Kim

[rustler]

Ian, Just out of curiosity, what was the cheapo 2nd. hand engine you found at the LHS? Kim

Hi Kim. Trust you are well.
SC36 R/C. Good as new. £20/$32. Needs venturi/NVA.