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Old Feb 22, 2009, 03:40 PM
Robot, RC Pilot & Builder :-)
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Roanoke, VA, USA
Joined Jul 2006
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Flaps for EasyStars

Here is a description, with some videos, of the flaps I made and have been flying on my EasyStar RC airplane models.

Why I made flaps for my EasyStars: I wanted to be able to land slowly and gently, in small, confined areas, with my FPV EasyStar, and the flaps have helped me a lot with this.

I like the flaps so much, that I now move the one set of wing-halves, with the flaps, back and forth between both of my EasyStars, so that I always have the flaps available. :)

Since most of this info has been discussed in the EasyStar forum, I decided to post it here, in a FAQ/discussion format. Perhaps someday I'll edit all of this down into something more concise, but until then, here it is.

Thanks to all of my friends who have encouraged me along the way with this project.

Who Taught Me: I especially must thank Teccer & Marckossa, for leading the way with building flaps for their EasyStars, and for guiding me through this process... and for allowing me to copy their flap designs... Thanks!

I edited some of the postings, for conciseness.

If I quoted you in a post, and you'd prefer not to have your name in this FAQ, just let me know, and I'll remove your name, and/or what you wrote, from this FAQ.

I hope this is helpful information,
Kevin

A Few Details:
1. The dimensions of my EasyStar flaps are copied directly from Teccer's excellent design:
-start 3” from fuselage
-14” long
-1.75” wide
-fully deploy downward to about a 45 degree angle

2. The servos (Futaba 3114 servos) are located under the wings, and pull the flaps down & forward. Since I use landing gear on my EasyStars, I have a few inches of ground clearance, and I takeoff and land on paved surfaces and grass, not rocky surfaces, so the servos are safe being placed under the wings.

3. The underside of the hinge is taped, where the flap meets the wing, using 3M Scotch brand clear Storage Tape, "3650 Series".

4. I placed the flaps on a three position switch, but I typically deploy the flaps at 100% when I use them for landing.

===
Video comparison of landing with flaps and with no flaps:
EasyStar Flaps - Landings with & without Flaps 2009-05-07 (0 min 53 sec)


An AV (non-FPV) vertical dive landing at 3:40 in this video:
EasyStar Aerial Video on a Snowy Day with Smooth Landing & Vertical Dive Landing (4 min 33 sec)


An FPV flight includes a landing using the flaps:
EasyStar Flew via FPV Landed w Flaps & FPV 2009-02-14_0002.wmv (2 min 21 sec)


Some Vertical Dive Landings with Flaps:
EasyStar with Flaps Vertical Dive Landings aka Combat Landings (1 min 45 sec)


How the flaps are controlled via servos:
EasyStar Flaps Actuation - Close-Ups (0 min 50 sec)



================================================

Quote:
Originally Posted by jbeckett
Great! I really like the short landing run.
JB, Thanks!

The flaps help a lot to shorten the landing run. I built the flaps according to the plans posted by Teccer & Marckossa, and their design for the flaps works very well.

While I was gliding in to land, a buddy standing near me and spotting for me told me "you're too high, Kevin, you're going to over-shoot", which reminded me to deploy the flaps. :)

Thanks,
Kevin

================================================

Quote:
Originally Posted by MinimumWage
Kevin,

Neat video! The EZ looks like it practically floats with full flaps down!

Mike
Mike, Thanks!

Yes, with the flaps fully down, the EasyStar slows way down, making it much easier to land, and less likely to be damaged, which helps to reduce my stress while flying by video (FPV). :)

In fact, I just returned home from two more FPV flights with the EasyStar; and on my second flight, to land, I deployed the flaps, gave a little nose down to the elevator, and just let it fly slowly down to a soft landing.

PS - Welcome to RCGroups and to the EasyStar thread!

Thanks,
Kevin

================================================

Quote:
Originally Posted by scrtsqrl
Kevin,
Thanks for all that info.
I think I'm going to get the 2.1 mm lens and try out flaps... :)
JBB
JBB, I'm happy to help. :)

For anyone interested in making flaps for their EasyStar: I simply copied Teccer's & MarcKossa's work:

1. Teccer posted:
a. http://www.rcgroups.com/forums/showp...postcount=1912
b. http://www.rcgroups.com/forums/showp...postcount=1911
c. http://www.rcgroups.com/forums/showp...postcount=2319

2. Marckossa posted: http://www.rcgroups.com/forums/showp...postcount=2470

3. and I posted: http://www.rcgroups.com/forums/showp...postcount=4158

I like the flaps so much, that I now move the one set of wing-halves, with the flaps, back and forth between both of my EasyStars, so that I always have the flaps available. :)

Best Regards,
Kevin

================================================

Quote:
Originally Posted by dirtman
Hello Kevin,

Do you mix in your down elevator or just push the stick? Do you come in with some power on with the flaps?
Hi Dirtman, Thanks for your post.

I don't have any mixes set up for the flaps. I find that there is a very mild, nose-downward pitching moment that occurs when I deploy the flaps. It's really only a small pitching moment, and I just pull back a tiny bit on the elevator stick, in order to compensate for the flaps' pitching moment.

Or I push the stick a bit, to put the flapped EZ into a slight dive, until near the ground, and then I pull the stick a little, to flare for landing.

Please be aware that it's difficult to predict in advance, if flaps will cause an upward or a downward pitching moment, as many things affect this, including the amount of flap deployment, and how the airflow from the flaps hits the horizontal stab. I have a buddy who recently finished building a scratch-built (and beautiful) Fielser Storch model, and when he deploys his flaps, his model has a large upward pitching moment, which is the opposite direction of the pitching moment on my EasyStar with flaps deployed.

Thus, the advice to test the flaps "three mistakes high", to see how they will affect the flight characteristics.

To land my EasyStars, I normally glide in with the throttle turned off, so as to land as slowly as possible. This is true whether I'm landing an EasyStar with flaps or without flaps.

I have taken off with both 50% and with 100% flaps, and it seems to take off alright either way. I don't know if the stock power set up would be able to do this... I have a brushless motor and a 3S Li battery.

Quote:
Originally Posted by dirtman
Why did you decided to use flaps instead of Flaperons? the only reason I can think of is you are using a 4 channel rx when you would need a 5 or greater for flaperons.
I have a Futaba 9CAPS Tx, and an 8 channel Rx in the model, so I have 8 proportional channels available.

I chose to build flaps because it's easier (i.e., less work) than building ailerons. :)

Also, reading about the great results Teccer & Marckossa achieved with flaps, and the so-so results most people have reported with ailerons on the curved EasyStar wings, combined with less work, made my choice easy.

The people who have reported good results with ailerons on the EZ, typically have flattened their EZ wings, and I did not want to flatten my EZ's wings, as doing so would reduce the effectiveness of steering with just rudder, and also decrease the natural stability of the EZ design in roll. I like my EZ's to be stable in roll, and to steer with rudder. :)

Quote:
Originally Posted by dirtman
I ask because you have the ailerons installed, you might as well take advantage of them.
I don't have ailerons installed, since the way I cut & hinged the flaps, they can only move downward, they are not capable of moving upward.

Quote:
Originally Posted by dirtman
I have ailerons installed on mine and having positive wing control is so nice.
Cool. :)

Quote:
Originally Posted by dirtman
I get a lot of nose drop when I use the rudder, I have a large rudder, with very little throw and it still kicks the nose down.

Anyways I find it much easier to make a flatter turn with the ailerons than with rudder and elevator believe it or not.
I do believe you; ailerons do give greater control. I have ailerons on a couple of other aircraft models, and the additional control is nice to have.

I just pull back a little on the elevator during turns, to keep the nose up.

Quote:
Originally Posted by dirtman
And flying in any sort of wind or turbulance is not much of a problem with the extra control
I believe it. Ailerons would be nice to have.

Quote:
Originally Posted by dirtman
Try the ailerons out, you might like them :)
Please post photos of how you built your ailerons. I would like to understand how you did this and how they work for you.

Did you flatten your EasyStar's wings, for the ailerons?

Thanks,
Kevin

================================================

Quote:
Originally Posted by WTurbiasz
Kevin just the opposite I think sharing the flap idea is very helpful as Im sure Im not the only one stuck in a small field where you don't always have the option of having a half mile to land in. As it is now if I want to I can walk out the door and fly from the road but getting the EZ back requires a deep dive and a hard landing just to slow her down. Flaps will fix that issue for me.
Tek, You raise an interesting point... I've wondered about how small an open field I can land the EasyStar with flaps in.

I have put the EasyStar, with flaps deployed, into about a 45 degree dive, then pulled out at the last moment to touch down gently... but I have not yet pushed it to see how steeply I can dive the EasyStar to land, to determine how small a space I can land it in. I have wondered if a truly vertical dive to landing is feasible... I suppose I'll find out. :)

I'll record video of putting the EasyStar into a steep dive and pulling out at the last moment, to land.

I'll post whatever I learn, and if you do anything similar, please post what you learn.

Thanks,
Kevin

================================================

Quote:
Originally Posted by latin105fm
Kelvin, silly question. Those flaps, you only use them when your landing to slow you down?

Dan
Dan, Good question.

I am primarily using the flaps during the (typically unpowered) landing approach, in order to both slow down the plane, and also to steepen the glide slope descent angle.

The flaps accomplish the following for me:
1. The flaps create drag, which slows the plane down a lot, which is nice for a slower, gentler landing.
2. The flaps create lift, which means the plane can still maintain enough lift while flying slowly, without stalling and crashing.
3. The flaps increase the steepness of the glide slope descent angle, which means being able to get the EasyStar down into a smaller area which is surrounded by trees or other vertical obstacles.

I have experimented with using the flaps at other times, like during takeoff, and during slow flying, and with my fairly powerful brushless setup on a 3S Li battery, the motor can overcome the drag of the flaps, to fly and even takeoff & climb out from takeoff with flaps deployed. I don't know if the stock, brushed power system would have enough thrust to takeoff with flaps.

I hope I answered your question,
Kevin

================================================

Quote:
Originally Posted by Rickochet
Nice job on the flaps. I have seen most of the mods with ailerons, flaps, spoilers, spoilerons and flaperons. I was curious which is the most effective in reducing speed for landing?

Rick
Rick, Thanks! I appreciate your kind words.

I apologize in advance for the length of this post. I did a lot of research on this very question you've asked...... sorry if this is too much technical detail.

The short answer is "FLAPS".

For slowing for landing, the best options, in order, are:
1. flaps
2. flaperons (but watchout for tipstalling with flaperons!)
3. side slip, as Flypopa mentioned, using the ailerons turned one way and rudder turned the other way, to cause the aircraft to "slip" partly sideways, causing drag and slowing the aircraft (note: I believe this requires an aircraft to have some dihedral (or, more precisely, stability in roll), so that the rudder's yaw input creates some roll input, so that the roll induced by the ailierons is countered by the roll induced by the rudder).

Here are the details why:
Since I don't have ailerons on my EasyStar, I don't have experience comparing the effectiveness in reducing speed, but I do have ailerons on other models, so I feel comfortable giving you my opinion, based on my experiences as well as my study of this subject. However, I do not have experience flying with spoilers, although I have spoken with pilots who do use spoliers, and I'll share what I have been told and what I have read about spoliers.

Spoliers & spoilerons help the aircraft lose lift (i.e., "spoil" lift), which causes the aircraft to quickly lose altitude, but without slowing down very much. Thus, spoliers are used in glider contests to get a glider to quickly drop down onto a landing zone target. Spoilers & spoilerons are intended to NOT reduce speed very much, and so I left these off of the list, above.

Ailerons can be setup as flaperons, which gives both the benefits and the drawbacks of both, except ... ailerons generally need to be near the wingtips, in order to get a quick roll rate, while flaps need to be near the fuselage, and away from the wingtips. Flaps (or downturned ailerons) will generally stall before the rest of the wing (due to the higher angle of attack), and a stall near a wing tip will cause that wing to rapidly drop (a tipstall), which usually results in a crash if you are near the ground (like during a landing approach). I've experienced tipstalls with many models (usually the more aerobatic models are designed to take advantage of tipstalling, and thus tipstall more easily, while "trainer aircraft, like the EZ, are designed to resist tipstalling).

Thus, flaperons have both the benefit of ailerons and flaps, except that the flaperons cannot be used to slow down as much for landing, compared to regular flaps, due the flaperons generally being nearer the wingtips, and potentially creating tipstalls at low airspeeds.

And since we are on the subject, when people talk about the "dreaded downwind turn" what they are actually describing is a tipstall... where, at low airspeed, and while banking for a turn and then trying to roll out of the turn, the lower wingtip stalls, then that wing falls, and the plane rolls over and drops suddenly, resulting in a crash if near the ground ... or to perform an aerobatic spin, if done at sufficient altitude. Flaperons would be more susceptible to this than regular flaps, due to the flaperons being nearer to the wigtips.

If you are interested in how to optimize the design of your aircraft's wings, a few excellent references on aircraft design, including RC model aircraft, include the following (I own copies of and have read these excellent books):
http://www.amazon.com/Basics-Model-A...5321975&sr=8-6

http://www.amazon.com/Model-Aircraft...5322118&sr=8-4

http://www.amazon.com/Simplified-Air...5321975&sr=8-3

That's why I decided upon building flaps for my EasyStars' wings.

I hope I answered your question! :D
Kevin

================================================

Quote:
Originally Posted by scrtsqrl
Kevin,
Thank you for that. Very helpful.

One question though: Is there a reason the servos are below the wing intstead of above the wing? I'd imagine on a a plane w/o gear like the EZ* the risk of damaging the servos, linkages, etc are quite high.
JBB, Thanks for your kind words. :)

You asked a very good question which I thought about a lot... here's what I concluded:

1. Both of my EasyStars have landing gear (primarily a CF tube passing through the fuse, with 4" diameter GWS lightweight wheels, retained on a piece of piano wire), and I plan to land in areas which are either paved or grassy, not rocky ... So I have enough ground clearance to mount the servos either above or below the wing.

2. When the flaps are deployed (i,e., pointing downward), each flap will experience a rearward aero-loading force, due to the wind hitting the flap and the wind pushing rearward on the flap.

The simple packing-tape hinge (I like it simple), going along the underside of the wing and flap, will thus be pulled rearward by the aero-load on the flap. I.e., this aeroloading force will tend to want to pull the tape off of the wing & the flap.

3.A. If the servo is mounted on top of the wing, and the control horn is thus mounted on top of the flap, then to deploy the flap, the servo must push on the control rod, which will exert a rearward force on the flap. This rearward force of the servo on the flap will add to the rearward aero-load force on the flap, and this larger combined rearward force must be countered by the tape hinge being in tension, which could eventually pull the tape hinge loose from either the wing or the flap.

3.B. However, if the servo is mounted under the wing, and the control horn is thus mounted under the flap, then to deploy the flap, the servo must pull on the control rod, which will exert a forward force on the flap. This forward force of the servo on the flap will counter the rearward aero-load force on the flap, and this smaller overall force on the flap will require less force on the tape hinge (i.e, the tension in the tape hinge will be reduced), which reduces the likelihood of pulling the tape hinge loose from either the wing or the flap.

And just to be sure, I ran all this by a friend who is an experienced mechanical engineer, who also flys RC aircraft, and he agreed with the above analysis of forces loaded onto the flaps and the hinges.

I hope all of this makes sense. Please let me know if any of this is unclear.

On the other hand, if someone else needs to land in rocky areas, or otherwise expects the servos will strike ground objects, then it would be more robust to place the servos on top of the wings... and then I would also use a more durable hinge, like nylon hinges or CA hinge tape, rather than simple packing tape under the wing & flaps, due to the increased loads on the hinges.

Edit: PS - One other reason to put the servos under the wing, for flaps, is this puts the pushrod in tension, not compression, so that you can use a thinner, lighter pushrod diameter, since in this confguration, the "pushrod" really only needs to pull, not push, so it will not buckle from being compressed too much. This same technique is useful for mounting elevator control horns on top of the elevator, as the largest force (load) on an elevator is likely to occur when pulling up & out of a high-speed dive, so putting the pushrod on top of the evelator means the pushrod will be in tension during this high-load manuever... if the pushrod were mounted under the elevator, then when pulling out of a dive, a thin pushrod might buckle due to the large compression load... I hope that all makes sense! :)

I hope I answered your question! :D
Kevin

================================================

Quote:
Originally Posted by jpgcag
Kevin,

Great explaination. Now you've got me thinking about my own aileron project. I was going to cut in ailerons 1/2" out from the wing root and make them 15" X 1 1/2". Since I was going to make them do the work of both flaps and ailerons, but at the same time keeping them closer to the fuse, (I have some extensions I want to use up.) I figured I'd put the servos about a third of the way out at about 5". I'm wondering if the servos will have enough leverage to fully activate the flaps since they won't be in the center of the aileron panel?

Any thoughts?

Thanks in advance.

Jack
Jack, Thanks!

That's a great question. If it were me, I would play it safe & add the cost & weight of servo cable extensions, and place the servos in the middle of the aileron panels, since I don't know how far off-center the servo can be or what the impacts of placing the servo off-center would be.

Or... you could experiment in order to determine how far off-center the servo could be, before any issues arise.

I used Futaba servo model # 3114, http://www3.towerhobbies.com/cgi-bin...?&I=LXNCV6&P=M, as these weigh 0.28 oz, have 21 inch-ounces of torque, and a speed of 0.10sec/60degrees, at 4.8V. I previously had preferred the blue-cased, Hitec HS55's but I found that for a dollar or so more, I could get the Futaba 3114's, with more torque, and almost twice the speed of the HS55's, so I used Futaba 3114's for my flaps.

What servos do you plan to use?

Please post pictures of what you build! :)

Good Luck!
Kevin
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Old Feb 22, 2009, 04:18 PM
Lost it again!!!!!
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Great Job Kevin
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Old Feb 22, 2009, 04:25 PM
Why so serious?
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Fantastic.
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Old Feb 22, 2009, 06:30 PM
Real Time Recon
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Kevin,bring that bad-boy over,we'll have 2 go flying ...RTR
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Old Feb 22, 2009, 08:22 PM
Robot, RC Pilot & Builder :-)
kevinhines's Avatar
Roanoke, VA, USA
Joined Jul 2006
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Quote:
Originally Posted by dirtman
Great Job Kevin
Quote:
Originally Posted by 2500GENE
Fantastic.
Dirtman & Gene, Thanks!

Over the next few days, I plan to add more details about the flaps, so that someone can read this and determine how to make this mod.

Quote:
Originally Posted by realtimerecon
Kevin,bring that bad-boy over,we'll have 2 go flying ...RTR
Roger, I think it's your turn to come over to my place to fly, isn't it? Thanks for the invite!

Thanks,
Kevin
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Old Feb 23, 2009, 06:37 AM
Real Time Recon
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smith mt. lake VA.
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Quote:
Originally Posted by kevinhines
Dirtman & Gene, Thanks!

Over the next few days, I plan to add more details about the flaps, so that someone can read this and determine how to make this mod.

Roger, I think it's your turn to come over to my place to fly, isn't it? Thanks for the invite!

Thanks,
Kevin
Lets set a date
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Old Feb 23, 2009, 10:11 PM
Lost it again!!!!!
dirtman's Avatar
United States, CA, Menifee
Joined Aug 2007
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HC 9g servos and flaps

Ok I have fried 2 htx 9g servos in my EZ* on the flaps in the last few weeks
the first one I thought was a bad apple, but now 2

Posted the story here

http://www.rcgroups.com/forums/showt...7#post11655788
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Old Feb 24, 2009, 12:04 PM
Robot, RC Pilot & Builder :-)
kevinhines's Avatar
Roanoke, VA, USA
Joined Jul 2006
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Quote:
Originally Posted by dirtman
Ok I have fried 2 htx 9g servos in my EZ* on the flaps in the last few weeks
the first one I thought was a bad apple, but now 2

Posted the story here

http://www.rcgroups.com/forums/showt...7#post11655788
Dirtman, For my EasyStar flaps, I am using Futaba 3114 servos, http://www3.towerhobbies.com/cgi-bin...?&I=LXNCV6&P=M, which are rated at 4.8V, to have 21inch-oz of torque, and a speed of 0.10sec/60degrees. I have about 30 flights with these servos operating the flaps, and these servos have performed very well for me.

What are the sizes of your flaps? And do you have any binding in the movement of the flaps?

What are the specs on the htx 9g servos you tried to use?

Good Luck!
Kevin
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Old Feb 24, 2009, 12:29 PM
Lost it again!!!!!
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the ailerons are 15x1.5" and here are the servos

http://www.hobbycity.com/hobbycity/s...ec_Micro_Servo

I think that trying to hold the flaps with the wind resistance is just to much for the servo and it overheats? It is a $4 servo, maybe I just got a bad batch, but as I have said, both servos are different on the inside, differnt circut boards
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Old Feb 24, 2009, 09:21 PM
Robot, RC Pilot & Builder :-)
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Roanoke, VA, USA
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Quote:
Originally Posted by dirtman
the ailerons are 15x1.5" and here are the servos

http://www.hobbycity.com/hobbycity/s...ec_Micro_Servo

I think that trying to hold the flaps with the wind resistance is just to much for the servo and it overheats? It is a $4 servo, maybe I just got a bad batch, but as I have said, both servos are different on the inside, differnt circut boards
Dirtman, I've never used the HobbyCity servos... the Futaba 3114's have been working well for my flaps, so I am happy to recommend them. In fact, I even bought a couple extra, as I know I'll use them in future projects.

Kevin
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Old Feb 24, 2009, 09:40 PM
Lost it again!!!!!
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I decided to put in some hs 81's I had, way overkill but they do a fine job. Still bumbed about the 9g, I still think they are great servos for regular flying, They just cant handle being held on for any length of time like for flaps.
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Old May 10, 2009, 03:33 PM
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Video of Flaps vs No-Flaps Landing

I finally have a comparison video (from a spectator's viewpoint) comparing the landings of my EasyStar, with flaps, and without flaps.

I hope you like it,
Kevin

PS - I also added this video to post #1.

EasyStar Flaps - Landings with & without Flaps 2009-05-07 (0 min 53 sec)
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Old Mar 02, 2010, 06:44 PM
Robot, RC Pilot & Builder :-)
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Recently uploaded another video, using the flaps to dive vertically, then to land gently.

The vertical dive to land occurs at 3:40 in the video.

PS - I also added this video to post #1.

Best Regards,
Kevin

EasyStar Aerial Video on a Snowy Day with Smooth Landing & Vertical Dive Landing (4 min 33 sec)
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