Dihedral removal????
 

I am basically outgrowing my Hanger 9 Alpha trainer. I can do just about anything the plane can deliver, and have run almost 3 gallons through her. I am currently building a SIG Hog Bipe as my second plane, but it's gona be a while before she is done. I have been thinking about removing the dihedral from the Alpha trainer to give me better roll rate, and performance and prepare me for the flight characteristics of the biplane. Has anyone removed the dihedral on this plane, and has it helped?? Or am I just better off keeping the wing the way it is??? Let me know your feedback.

Dihedral removal????
 

After a small mishap with an avistar trainer I fixed the wing sans dihedral...put a os 52 four stroke on it and put a servo on each aileron. Cranked up the throws to "all you can get" and YAHOOO.
Wonderful improvement!
Goforit

Dihedral removal????
 

There's a guy who flies an avistar at our field with a flat wing. I asked and he said he just ordered a new wing for it and put it together minus the dihedral so yes it's possible.

Dihedral removal????
 

Flys way better with no dihedral. You will like it

Dihedral removal????
 

Thanks for the responses, I think I'm gonna try it.........

Dihedral removal????
 

DON'T BUY ANOTHER WING! you can do much more than take the dihedral out, and buying a new wing don't solve them 3 gallons is not much, so stick with her for another gallon or so. then, you you want performance, here's what you do. First, replace the fcontrol surfaces with bigger ones. this is not difficult. your local hobby shop will have hinges and aileron stock (which is what you use for your elevator and rudder as well). get the ones that do not twist as easily. those are usually the tighter grained ones. they are bade of balsa. so are the ones on your planes. if your ailerons are 1 inch stock, replace them with 2 inch stock. you can taper cut the edges and you will never know. same with your elevator and rudder. covering is also easy. 3 practice tries and i was able to do it. also, if you want to cut the tips off yout rudder and elevator you can make the tips part of the control surface for extra kick. The next step is to take a bandsaw to your wing. find out how much dihedral your wing has, and set the bandsaw to half that so you can lay one wing half flat, and it will cut through the center, leaving an equal half the dihedral on both sides. then, set your bandsaw's cutting angle to zero again. lay your wing flat, and cut it on both sides. voila, no dihedral. if you want to drill a hole through the glued in wingspar, you can put in a carbon fiber or aluminum wing tube. you can make it removable that way, but if you want, you can just glue the tube inside. it will be stronger than your previous spar. convert your wing to bolt-on if it already is not. you will have a pretty good flying plane. it will have a lot of control, it will stay where you put it, and it will respond a lot crisper to control imputs, as well as not get so mushy at landing speed.

Do a Dumbo
 

A goal in a true Pattern plane is to achieve as close to total neutral stability on the pitch and roll axis as possible (not easy to do) and is sometimes called grovin or 'goes where you point it' as opposed to the high positive pitch and roll stability that is designed into a trainer and called 'self recovering' or self righting.

Removing the dihedral on a trainer will definately give more of that grovin type of roll character and is a lot more fun, in some ways easier to fly that way. However even with the wing totaly flat, it will still not be as close to a neutral stability in roll as a pattern ship and the reason is with a high wing cabin type even with a flat wing will still experiance a 'righting tendency' due the pendelum effect of the wing position or more properly a dihedral effect.

I think you will find it interesting if you are going to flatten a trainer wing anyway don,t stop there build in anhedral or drooping wings. Sounds crazy and looks silly but you will amaze yourself and your Buds how much better it will fly. Actually a low wing pattern ship needs a very slight amount of dihedral to reach that neutral point just the opposite of the high wing, or it may have a subtle taper in airfoil towards tip and the tips as well may be providing that needed dihedral.

I have 'bashed a few this way for friends and the results are delightful.

John

Dihedral removal????
 

I took the dihedral out with the thin blade on a table saw and man you wouldnt know the plane was the same.

Dihedral removal????
 

I think Spaceclam has the best approach and basically what I would recommend, so I'll amplify a little.

Trainers can do some awesome stuff, even with the dihedral. When I get a student that claims they have out grown their trainer (typically about ten flights after a solo), I ask if I can fly their plane a second. I then fly a rolling circle with their trainer... typically their mouth hangs open a few seconds as they try to figure out how I just did that with their trainer.

Point is, Trainers can be very aerobatic... even stock trainers.

Removing the dihedral will help some issues, but if you have a computer radio you can mix out the dihedral effects. Slave same side rudder to aileron (if you move left aileron, rudder moves left too) at about 30% to start. Then slave opposite aileron to rudder (left rudder causes right aileron movement) at about 30%. You can also crank up your throws. Find a good local pilot to help you set up the mixes.

Changing the ailerons, elevator and rudder as Spaceclam described will do more for you than removing the dihedral. But if you decide to start cutting the plane, you might as well remove the dihedral as you replace the control surface.

Cheers

Dihedral removal????
 

I'm surprised no one has mentioned this one (or I missed it if they did):

Move the CG back.

Most trainers have the CG really far forward. Moving it back will make it much more responsive and acrobatic. Added to the changes above, and it's amazing what a "trainer" can do.

Dihedral removal????
 

true, but the r4eason i at least did not mention it is if he puts bigger control surfaces on that also allow more throw, and no dighedral, if you add a rearward cg to the mix it is a setup for disaster especially with a newer pilot. also, you can't move the cg very far back without adding weight. the battery is usually right about where the cg is. there is a guy at my field who has souped up his trainer a lot. he is the presedent of our club. he has (remember this is a trainer) coreless servos on everything but the throttle, fuel pump, onboard alternator, tempurature monitored engine that regulates the fuel flow depending on the temp, a glow driver, retracts, sjock absorbers on every wheel, flaps, giant control surfaces, no dihedral, twin plugs, and a camera. It isn't very aerobatic, but it came in handy when the cat-in-the-hat movie was being shot 1000 feet from the end of out runway. we took pictures of them and they never even knew.

Yes to all the above
 

OK but lets not stop there aerobatics are not the only game in town that require skill and effort (read fun) that trainers are ideally suited for.

Just one of which is carrier landings: tremendous fun, harder than snot and little risk to the airplane aside from a few props.

Drill a hole through the fuse just in front of the stabilizer in the ply or a hard point and insert a piece of brass tubeing and drip some CA in. Run a long piece of music wire through and bend back to form a yoke then where they come together extend a single piece with a 'big' hook, wrap with copper wire and solder.

For the trap use a fifty foot piece of mason line tied to the handles of two milk jugs filled with water and stretch accross the runway.
For takeoff just let the hook drag, not a problem. Takes a surpriseing amount of practice but sure does wonders for your approach and landing techniques. When you finally make a successful trap its as pretty as you please and the airplane just angles down to the ground nice and soft. :) If you hit the prop or catch a nose wheel the result is not usually much differant except you will sacrafice a few props.

Give it a shot, The world does not just revolve around 3D (pun intended) :D


John

By the way no fair touching the runway before or after passing the trap if you 'bolter' then you have to complete the go around.

Dihedral removal????
 

i understand that, but you get a hog bipe because it is an aerobatic plane, and you wnat to increase your rates because he wants an aerobatic plane. he didn't say anything about carrier landings

Dihedral removal????
 

OK fair enough, But the original poster is at the point where he is bored with his trainer (in his words "out growing it") and I was merely offering a fun educational continued use for it, not suggesting he should not continue with other flying pusuits. So in that respect my reply was entirely appropriate.

John

Flat Wing Trainer
 

A high wing location is equivalent of about 3 degrees of dihedral. On planes about the size of a normal trainer, it takes 3 inches of anhedral to compensate for the high wing location.

I'm probably the anhedral fanatic of the world since I've built and modified several planes with anhedral. My latest is a Kangek SK-50 ARF with the 3 inches. It has a little pitch in knife edge, but does not roll. I can easily make several passes up and down the field while staying in knife edge. All rolls are better as the plane isn't fighting you. Outside loops also improved as the plane is no longer trying to right itself during the loop.

With an ARF, I usually invert the dihedral brace and adjust to get the amount I want. I fill the gap at the wing roots with aileron stock.

Recent past projects were a Joss Stick and an Easy Sport 40 ARF.

Contrary to what most people think, I have never found one bad trait in a high wing plane with anhedral. You can check out my anhedral planes on my web site.