PT40 dihedral
 

I do not have ailerons on my PT-40 (I know you will tell me to have them, but I already have it without). But I heard somewhere that the PT-40 kit's wing dihedral option A (for beginner's) without ailerons has a tendency to over-correct itself in flight. Is there any truth to this?

Is it possible to choose option B (which is the sportier version) without ailerons and still have it with the self-correcting beginner's characteristics? If you say it is possible and if it's true about the A option above then I would like to try to cut the wing in half and adjust the dihedral.

RE: PT40 dihedral
 

The PT 40 does self correct for the most point. Without ailerons, I would be inclined to leave the dihedral alone. Good Luck, Dave

RE: PT40 dihedral
 

Well....I cant help you alot,but I can maybe give you some to think about. I have a PT-40 and built it with ailerons and the option B sport wing. I really never needed the "recovery" features of this plane as I was always on a cord for my training days and I never really had the plane get too far out of control. And just from flying it,I never noticed any "recovery" habits of the plane. Maybe its the sport wing,but the only thing going to "recover" my plane if I screw up is me! If I let go of the sticks.....I'm gonna crash,lol. But thats ok,because I never needed it,and to be honest I dont think I would want it. If your gonna crash its most likely gonna be while your flying low or landing or something,and it will be too late for the plane to recover itself anyway.

Now as far as that dehidral goes......like I said,I built the sport wing and even the sport wing has alot of dehedral. And the only dang thing that dehidral seems to do is make flying it in the wind a hen of alot harder because wind and dehedral hate each other. I'll give you a pic of my plane,it might give you an idea of what the sport wing looks like. If you'd like a better straight-on picture of it,just ask.....I'll go out and snap one for you right now. My point is........I would generally not recommend the option A Trainer wing because I believe it would just be too much dehedral. BUUUTTTT,I've never flown a plane without ailerons. So that will likely have a BIG affect of weather or not you should need the extra dehedral. Hopefully after reading our posts,someone of more experience can give you some better advice.

You may also want to consider adding the ailerons too,especially if you end up splitting your wing anyway.

Just be very careful flying your new PT in the wind. Even to this day I dont fly mine in the wind because its just a bugger to land. With that dehedral plus a totally flat bottom wing.........it can be challenging it even slight wind. But I still do love flying it about once a month. With low wind,its a pleasure to fly and land.

RE: PT40 dihedral
 

Before you go cutting things up you need to slow down understand some points about flying conventional RC aircraft with two axis controls so you can make your own decisions. Hard to follow but it sure sounds like you were listening to folks who have no idea and are speculating. Have you actually flown it yet and find your conclustions to be fact?


Fisrt I want to make it clear there is nothing wrong with flying conventional sized glow trainers on two axis it can work fine and in some cases quite fun.


I am only going to address the so called self righting issue and the 'sportiness' of the handling issues. OK here goes:

For an airplane only using rudder for directional control to increase control response (sportiness)you increase dihedral to make it easier to fly and to slow the response you reduce the dihedral. A totally flat wing without ailerons cannot be controlled. All of this is opposite of what would apply with an airplane using ailerons.

Now how that applies to the so called self righting tendency: The self righting tendency will increase if you increase the dihedral and the tendency will be less if you reduce the dihedral

These two simple facts never change and will always apply. Now I know it seems odd that increasing the dihedral will increase the righting tendency and increase the sportiness (control response) but if you think about it thats a good thing and the go hand in hand. If you want to maintain much of the righting tendency but reduce control response you reduce the rudder throw or size.

I am not sure what the plans are suggesting for your two axis setup but I would be far more inclined to beleve them than listen to a bunch of heresay.

RE: PT40 dihedral
 

OK I will leave as is. So basically the saying that it over-corrects itself is false.

RE: PT40 dihedral
 

The term corrects itself may be a bit misleading. If you put the plane in a slight right turn and then let go of the rudder control, you will notice that the plane will want to come back to level wings. This will not happen quickly and it cannot be used as a safety feature, however it does help in learning. Good Luck, Dave

RE: PT40 dihedral
 

I would not cut the wing in half on the PT 40 until you have flown the pants off of it to the point you are ready to not only adjust the dihedral but also add ailerons.

RE: PT40 dihedral
 

For what its worth: I have PT40s with the larger dihedral angle and the plane is actually rather difficult to control when it gets windy because of this. OTher pilots when they first see the plane on the ground think that the builder made a "mistake" with the huge angle of the wings! I built a LT25 with only 1" dihedral and the plane will still self level if you leave the sticks alone but the plane flys very well in fairly windy conditions and will fly the circuit inverted until you run out of fuel if you want to. :D

RE: PT40 dihedral
 

I do not plan on flying during windy conditions and I do not plan on putting ailerons on this plane. And I would rather not construct new joiners to have the dihedral between the beginner angle and sport.

RE: PT40 dihedral
 

Leave it be, Its silly to start modifying the daylights out of it and you have not even started flying yet.

Winds are not a problem with a properly set up two axis larger trainer. Crosswinds on takeoff or landing are where that control setup is disadvantaged. Taking off, landing into the wind or in the air you will not be at a substancial disadvantge.

Time to stop researching it to death, finnish the airplane and get started.

John

RE: PT40 dihedral
 

DO NOT EVEN THINK ABOUT THE "A WING"! I say this from experience. I have two PT-40s, I built the first one with the A wing because I thought "I am a beginner, I should use the beginner's wing" - WRONG! Way too much of an angle, it makes the plane very difficult to taxi, take off or land with any cross wind, and it makes the plane not as much fun to fly. I was going to buy a wing kit, but it was $75, a new PT 40 kit was $90, so I bought the full kit and rebuilt, much, much better plane to fly! Now that my trainer is limiting my flying I took my older PT-40, converted it to a tail dragger, cut the wing in half and removed all Dihedral, extended the rudder and elevator, put high rates on the ailerons and replaced the .46 motor with a strong OS .61 SF. It is a ton of fun to fly now.

The PT-40 is a good little trainer, I really like mine, but the A wing is a mistake, everyone who I know who has had one (this is 4 -5 people at my club) agree - do not built it! Good luck and have fun!

RE: PT40 dihedral
 

If you have already built the wing, I would seriously think about cutting it, and using ailerons, you do not want to fly with 3 channels. Alternatively, don't cut the wing, but install the Ailerons, it will be a much better flyer.

If you are interested, I have a spare PT-40 "Sport" Wing, it was given to me by a guy who planted his PT-40 and trashed the fuse. It is yours if you want it. I am not sure where you live, but if you cover the shipping from Toronto, you can have the wing.

Feel free to PM me if you are interested.

Cheers!

Andy

RE: PT40 dihedral
 

I fly mine in pretty heavy winds, it is not a real problem with the sport wing, the A wing is a greater problem in the wind. PT-40 is a great little plane, you will enjoy it a great deal, but I would put in the Ailerons for sure, it is WAY better for 4 channels (I have played with mine using only 3 channels- so I can tell you from experience).

If you do decide to cut the wing, rejoining it is not that big a deal, I did it a few weeks ago, it takes a couple of hours to do the work, and then some time to let the epoxy dry, but it is really pretty easy to get done.

RE: PT40 dihedral
 

So, keeping in mind that I am still a beginner:

~ Build with option A (beginner) with more dihedral with ailerons
OR
~ Build with option B (more sporty) with less dihedral with ailerons

I prefer 3-channel but if you think I really should have ailerons, is it simple enough to convert it to two servos instead of the instructed one servo? If it can be done can someone provide details and graphics on how its done?

RE: PT40 dihedral
 

I started flying last year - believe me it is much easier to control 4 channels rather than 3. The A wing is just too much in my opinion, even the sport wing has a pretty big dihedral in it.

It is very easy to do the conversion, especially if you have not yet covered the wing. If you have covered, you will need to do some cutting, but no big deal, You are looking at less than an hour's work to get it done. Buy a small amount of Basswood - 1/4 X 1/2 inch stock will do just fine, build a little box with two servo mount rails, use Epoxy. Then get a Y Harness, you may have to cut the ribs a bit to get the harness through. It is really very easy to get done. These planes are pretty tough, you can do some mods to them with out doing any harm at all.

BTW - got your PM and replied, will look into the cost of shipping the wing to you.

Andy

RE: PT40 dihedral
 

Could I see some graphics on exactly how to do the two-servo conversion if possible.

That's one opinion that I should do the B wing. Any more???

RE: PT40 dihedral
 

I am convinced to build the ailerons but could someone show me how to convert to two servos.

Thank you.

P.S: Beautiful plane Jester. How fast does that beauty fly with the setup you have? What's it powered with?

RE: PT40 dihedral
 

OK, this is pretty basic, but take a look at the drawing, very simple, use only 30 min Epoxy to attach the rails and reinforcements.

RE: PT40 dihedral
 

Thank you manks. One final question. How many ribs in from the wing root should the rails be? And would you suggest the B wing which is more sporty or the A wing for beginners. I think I am leaning towards the sportier version.

If it has any basis to the decision, I am also converting this PT40 to a taildragger.

RE: PT40 dihedral
 

I will be going with the sporty B wing style. Thank you all.

RE: PT40 dihedral
 

I agree with johnbuckner. If the wing is already built: LEAVE IT ALONE

If it is not built, I would build the B wing and use ailerons. But, I would build it as designed with the single aileron servo. On this plane I do not believe there is any advantage to dual servos. The setup delivered in the kit requires less work, saves weight, saves money, and works fine.

RE: PT40 dihedral
 

I found on the first one I built that there can be a problem with the control arms getting caught inside the fuse, so I modified my second one to have two servos in the wing. For the extra $20 it cost I think it is worth it, it also makes the plane a bit easier to trim in my opinion.

I set up the plane so that the servos are close to the end of the ailerons, it is about 2 or 3 bays in from the fuse.

RE: PT40 dihedral
 

I also converted one to a tail dragger, it is tougher to handle on the ground, flying makes no difference. I epoxied some light plywood to both sides of the fuse where the gear would mount, then I used some good nuts and bolts with locktight to secure them, it works fine, have not had a problem in over 25 flights. I did lose the tail wheel on on flight.