Trying a different approach to a STOL

[L Edge]

I am definitely going to add a quick setup of brakes that will help with evaluation of ground testing. I also tried a very quick test of ground taxi of the fixed rear wheel using the rudder/throttle and it works 5 out of 5. That's why I need brakes.

So:
1) Review the video of taxing, takeoff and landing of the real Chinook.(#1)
2) Review the incidence angle video.(#18)
3) With the wing, elevator at a fixed incidence and thrust perpendicular to the black tube, and the flaps variable, how do we stop the nose up/nose down at takeoff and landing and flying level.

Looking for what you need to do to make my model replicate the real Chinook yes, even hover like it did. Explain how you would do it?

 

[L Edge]

Solved the strut problem so that sort of finishes the design of the wing.

I tied the struts to the landing gear to take the landing abuse. It consisted of a 90 degree bracket and the 2 support wires to the wing.

The upper brackets(front and rear) was angular installed underneath balsa wood which was epoxy to the foam. Holding the wing by the edges, it is real stiff when shaking it.

Installed end plates(remember I did that on each end of the flap) so there should be a different airflow pattern.

Brakes and CG next.

 

[Piotrsko]

Nose up/down: potloads of down thrust but with your horizontal stab where it is...that might give you a nose up coupling that makes the incidence issue worse. Since I am in a full flying stab mode today that's my recommendation, but yours is glued down. Might have enough throw to fly with mostly full down. Flaps probably need to be bigger to affect wing rotation, like maybe twice their current width. Think flying wing. I had one once that only flew once I added a horizontal flat non moving plate as kinda a stabilizer.

 

[L Edge]

Will waiting for answers decided to put a "kiss" brake since it might help with taxi tests. Just hot glue servo to frame.
Brake off

Brake on

Setting up 3 position switch so it will be off, wheel will drag along so speed, and extra pressure to prevent movement. Will set limits by -AT end, subtrim, and +ATend.

First run, try was do I have a fixed rear wheel with enough rudder to taxi with? (Yes)
Now will see if brakes work or not.

 

[Piotrsko]

Do it like real taildraggers: bit of down elevator, blip of power, full rudder. If you have servos on both legs, I would do differential brake steering tied to the rudder but right rudder right brake. It would be really cool if it would taxi with the tailwheel up off the surface

 

[L Edge]

Basically, there are 2 conditions I am looking at in order to do a successful flight. I hope to make a bunch of short videos doing taxis( on the ground and trying 6" to a ft) and then slow up. The angled elevator is the new problem of understanding.

Here's the bird dressed up and views of that. Need to balance and fix the nose setup after taxing tests. My stabilizer was added to the wing. It is a product of a NACA video that works well. More on that.

Not artist, so "stickered it". Has end plates as well as the flaps. Notice prop wash covers under and over elevator as well as rudder at all times. If I loose aileron control, still have rudder,elevator to fly trainer like.

I am trying my stabilizer on a straight wing which is scaled larger than my other uses. It works real well in high alpha situations of thinner foam so well see what happens with this thick foam.

.

Prop is 9 x 3/8 and fixed due to tube. Started off with a 6 pitch, held it vertical and it will move to fast. Choked it to slow action down.

Going to set brakes and try it in the cellar.

 

[L Edge]

Well, the brakes work real good . They hold, but sliding of the wheel takes over when too much thrust is added as well as plane's nose tipping forward.
Add enough power (from -100 to about-43) and the tail lifts up and then drops back or if you add small amount of throttle It very quickly gets out of control.
Added point is right now CG of plane is at 90% wing.

Now a bunch of problems are coming.
Move CG to 25% wing (very close to wheels)elevator pitch be controllable?.
Now look at what happens when you taxi in zero wind?
Add a 10mph surface wind, brakes on and what happens with brakes off and rolling.

Going to set up shallow throttle curve in TX and jig to hold plane tube level and see what happens.

@Piotrsko ,
Did you know you can take the throttle position and divide it into a 3 position analog switch. You set the divisions for each mode.

Mine:
mode 1-brakes are locked(power up to say 44%)
mode 2 -brakes oscillate for landing for STOL landing done by sequencer in radio.
mode 3- brakes released totally.

This is what it looks like.

 

[Taildragger]

Nice to see some brakes being used! I'm working on some 3d printed fishing line actuated disc brakes for my planes right now.

 

[Piotrsko]

Not familiar with current computer stuff, newest for me is a 2004 futaba 6ex and I never use the mixing options just elevons. Tis why I asked.

Angled elevator essentially reduces the angle of incidence down from +25 to perhaps +10 which while still high is more reasonable

 

[L Edge]

Nice to see some brakes being used! I'm working on some 3d printed fishing line actuated disc brakes for my planes right now.

First

Nice to see some brakes being used! I'm working on some 3d printed fishing line actuated disc brakes for my planes right now.

Make sure you post that in the works. Interesting project.

Again, want to thank you for showing that video above. It added another build project that I have in different stages. This one is no simple design. Chinook became the top of my list which now is in testing stages. I hope it makes it off the ground.

Finished the "Firebird" , working on A-10 64 mm EDF, and you stirred up my 2 old PITA VTOL's FC that has kicked my butt for years.
Spent over 20 hr's trying to get it right with the FC. Making some progress. Biggest problem is if you make the wrong change, it can crash your bird.

 

[L Edge]

Not familiar with current computer stuff, newest for me is a 2004 futaba 6ex and I never use the mixing options just elevons. Tis why I asked.

Angled elevator essentially reduces the angle of incidence down from +25 to perhaps +10 which while still high is more reasonable

 

[L Edge]

Good, you got the gold ring.

With the tube level, the prop is perpendicular to it.( my reference point)
The elevator is at 18 degrees and the wing is at 19 degrees.
The tailwheel make an angle of -11 degrees.

Go back to Pg 1 and the video with wing up 33 degrees . So it ups my odds to 30 % of flying .I will explain what made it work.

Got any other thoughts?

 

[L Edge]

It is really nice when undecided, you can jump to another project and I put together something for stage 1 testing. Success is about 15% if I tried to go for it as is.
If you watch Dan's video, brakes are on, adds power and pushes forward on the stick to get tail up and and then applies backpressure(releases brakes-I do not involve flaps now)to the stick so it drives the tail down--------------etc.

So to duplicate that in the cellar, I am fixing the wheels so no movement, have added a gyro to the frame that has only pitch control and going to see what happens. For those who have explored gyros, I am using a 3 position switch so I can have it off, normal and heading hold mode.
Starting in head holding mode(elevator now stays where I leave it) well see what happens.

Hope this gives me a handle on prop flow that is trapped under the fixed elevator segment and what happens when elevator is applied both down and up. Then maybe go on testing if brakes are released and see what happens. Can I keep the tube horizontal myself?

I will do a video next showing what happens.

 

[L Edge]

Did cellar run. Video no.

Results :
plane tips nose up--50 times Able to hold level 2 times, not for long.
Had CG at 50%, 40% 30% with flatten throttle curve from 30 to 45% throttle. If you move throttle from 35 upward steadily, tail pops off ground and instantly noses over. So ground effects under fixed elevator work.

Short version, then tried gyro in HH and normal gyro. Same.
Decided:
Next, so no other external forces, now need to taxi outside with airflow hitting the underside of the wing.(need also to look at flaps later, opposite force). So will this produce a counter moment to match the tail rising to level that is controllable by the elevator?

Actually, I would like a windy day of 20mph so I could explore without having plane movement. Have to deal with head camera if worth videoing.


Score:
1 attempt------------no plane damage

 

[Kilo Kilo]

neat concept, it's always fun to see the experimental ultralights that are more like RC planes than other full scale ones. Might build something similar this winter. All my planes are belly landers since I fly off a rough grass field. I'd love to have something with big tires that I can do touch-and-go's with.

 

[L Edge]

Today, winds running from 5 to about 20mph with temp at 35 degrees. Went outside.

Simple result- had to unlearn everything I did trying in cellar. Did as above with brake locked and wind blowing. Tail down, then just flips nose over and even used holding full up elevator to stop it, doesn't work. So were going to have a touchy system.

What say I don't start off with a nose down elevator and just add power as is. Prop blast under brought it up as well as surrounding wind.

Progress results--nose leveled off with some controlling elevator movements at times. Wind would change speed and it would go off kilter. Tried it many shots until I now know position of throttle that's close to tail liftoff. Then tried a few times to release brake and erratic results.

Now know it is time to seek a shielded area between narrow buildings(knock out winds) and try more actual moving taxi tests. Froze my butt and hands after 35 min.

Score:
2 attempts ---still no damage to plane Sure glad prop is behind wing.

 

[L Edge]

Today, mid forties.
Decided to see what will happen if I start taxi test with power and very little wind.

Pulled up elevator and added some power to motor. Went slow. Next tried, neutral elevator and added power. Tail wheel rose as ground speed increased and explored position of throttle to keep tail horizontal. It is a balancing act where it took many runs to start getting the feel of it to keep it level. Very very touchy.
Best way of describing it -- take a marble and put it on a piece of flat glass and center it, walk with it and try to keep the marble in the center.

So now I tried for some faster speed. If you add power too fast, nose goes over and you skid to a halt. (no damage, prop is aft).
After a bunch of runs, I probably was able to go about 50 ft with tail wheel off ground.
Practicing, going upwind and level, the left wing lifted suddenly off the ground and I did a nose and right wing slide.
Tried a number of runs up and down wind again(throttle about the same) and times it did the same, and times it lifted the right wing and slid.
I used the rudder to try to counteract, but too fast. I was hoping it would act like a WW2 tail plane with the rudder, so?

Rather than quit, tried the same procedure with flaps partially and then full down. Throttle was kept in same position, result, the nose down
attitude drove the tail up quicker and backed off so I don't destroy the bird.

Score:
Plane received scratched wingtips and broken off endplate(glued back on)
Pilot gathered data to work on as what to do next.

Chances to make it fly---25%

 

[L Edge]

Here is a short sample of ground runs to see how it is going to to act. With flaps down, it seemed to lift off sooner, but elevator and rudder are super sensitive. Have no expo added for unsure of what can happen. Want full range of controls. CG at present is about 27% of wing and all control surfaces have equal deflections included the flaps. My camera man(me) didn't get the hat angle right. Sorry!!!

Going to try taxi runs with wind (10-20 mph) next couple of days and see what is going to happen. I reason this approach so if it jumps into the air, and I can keep it a few feet off the ground, might be able to save it.

This is my third exploration of using a angular wing . Watch and see what can happen were the first vid shows the fuse was not kept horizontal and second was. Trying to duplicate a CL-84. Learned quite a number of pointers to use with the Chinook. Notice breaking ground.

Again, bad hat cam.

 

[Mr NCT]

It looks like it will almost hover!

 

[L Edge]

Today, 34 degrees and gusty winds to 25mph. Beautiful day to test the Chinook. Between building and bottom of steep hill, winds would come roaring down narrow strip straight or in a swirl(like windsurfing). Glad I had brakes on the plane for it was going backwards just sitting there.

Exercise was just get tail off and stay horizontal and keep going a little faster each time and see what happens. This was done a number of times trying it-- no flaps, flaps about half down, and full down.

As you can see, swirling wind getting under the wing tends to flip it as you try to speed up or as a gust hits it. Had to add more up elevator to radio to help recovery the nose going down. Very touchy.

The second segment at 58 secs, lifted due to a wind gust and it lifted straight off the ground.
At 2;40 (going for it), it got airworthy and I (chopped throttle) to go home to warm up.

Score:
3 attempts__-plane's rudder and elevator loosened off horizontal rod when movable elevator portion (in down position) hit ground when being blown backwards by a gust.. Chances now--35% success

Results:
1) Getting more comfortable on keeping horizontal bar level. About half throttle and midway for flaps.
2) Will not lift off until bar is horizontal and wing is level. Flaps will be 1/2 way down.
3) Need calm or light winds(not swirly) to go for maiden flight.
4) Will try for level flight about 1-2 ft off deck and enough throttle to keep a good forward flying speed. Unknown is the result vector analysis of forward motion, lift and drag of the angular wing and the position of the CG.
5) Turns need to be very shallow(flips-going to use all 3 axis controls) and a keen sense of throttle management to stay away for stalls and roll overs.

Any other suggestions from watching tilted wings?