Supra "crawl" settings

[loic_debisschop]

With thinner and less cambered airfoils being more and more used on F3J airplane, it become sometimes hard to slow down some gliders for landing.
For example, it seems to me that the supra is, in general, harder to land than other F3J models.
I've seen that new nosecones are proposed, which may help to prevent the plane from bouncing when touching the ground... I've also seen that Mark Drela uses a "crawl" setting for landing: for half stroke of the brake stick the aileron are down: +8mm which give maximum lift.
For full stroke the aileron are up as usual for maximum drag. I fully agree with the principle of that: to fly slow the glider need the maximum lift.
In practice i tested this setting a bit and i saw the benefit of it: the speed can be dead slow. But, on the other hand, i find the approach much harder to deal with: the slope is harder to control, and the axis to the spot is also harder to keep.
Do anybody use this "crawl" settings ? What is your feedback ?

Loïc

[jtlsf5]

I have used the crawl setup for about a year on two Supras, a 63 oz carbon light and a 68 oz full carbon. I adjust elevator comp to ensure that it never slows so much that the plane becomes unmanageable. I also use a higher Aileron-rudder mix in landing mode, which immediately helps with tracking whether at the 50% (crawl) point or 100% (full flap) point. I still need to use independent rudder to correct wind caused course changes.

I have found that I use this mostly for setting up my approach prior to final and then approach at a slightly higher angle as I near the short final. At this stage I transition to full flap/crow for the final stage of the landing. It has been very effective.

JT

[OVSS Boss]

I am, and still evaluating the results.

Marc

[ClayH]

I've been trying to decide if there was anything I could do to get an all glass Supra to slow down more in the zone. I seem to have so much better control of my carbon 68 Perfect on landings. I bought a new Supra for light conditions, but am thinking that perhaps I should have tried a Perfect SL instead. How steep an approach are you guys making the last 8-10 seconds of the flight?

Clay

[trend.ab]

I feel I can control the Supra at least as well as the Perfect in the landing zone. When those flaps go out, it slows down stronger then anything else I have. I can even fly quite a steep angle in that setting without the plane accelerating. I have not been able to do that with the Perfect.

I used to fly Drela's setting for "crawl". But in an afternoon session with Joe Wurts, it turned out that his normal crow setting was more effective in directing the plane to the point. I am flying normal crow since then.

Beat

[Robglover]

I tried the crawl mode and went back to straight crow. The Supra can easily be slowed down so much that the controls become ineffective. That's too slow for my tastes, I do better with a bit more speed.

[John Walter]

With thinner and less cambered airfoils being more and more used on F3J airplane, it become sometimes hard to slow down some gliders for landing. For example, it seems to me that the supra is, in general, harder to land than other F3J models.

Loïc

Wow. This is the first time I have hear a concern about the ability of a Supra to slow for landing. I certainly didn't hear that from any Supra flyers at the F3J WC this summer.

[Phil Barnes]

The concerns that I heard about the Supra being harder to land had to do with the nose shape which tended not to stick but rather was more likely to slide on landing, and also a lack of elevator control authority which made it harder to pitch the nose down at the last second to stick the landing. Take that for what its worth, as second hand information from a tow person.

[John Walter]

Phil is correct regarding the tendency to bounce if there is insufficient angle on landing (read dork) if flown in F3J where no skegs are allowed. However, AJ McGowan had 100 point landings 9 out of 12 times in the preliminary rounds of the WC, so it can stick without a skeg.

Regarding understabbed, DP scored a 100 landing at the F3J WC with his stab broken and half of it dangling down! :D

[ClayH]

I should have made the question more of handling characteristics rather than flying speed. But I suppose Perfect vs Supra in the landing zone should be a topic for another thread.

Clay

[OVSS Boss]

Clay, you asked about how steep the approach is in the last 8-10 seconds, hopefully nice and flat and low. DP taught me this, in the last 5, I want to be on the deck and have a little forward going so I have control that is crisp. I use the crawl when I am trying to burn time from being early. But my ideal is to not steep if in any way possible, no matter how big the flaps, these ships do not slow down if they are pointed down at the ground.

Marc

[Phil Barnes]

....AJ McGowan had 100 point landings 9 out of 12 times in the preliminary rounds of the WC, so it can stick without a skeg.

Regarding understabbed, DP scored a 100 landing at the F3J WC with his stab broken and half of it dangling down! :DYou can overcome a design deficiency with enough piloting skill. That's not a dig at Mark Drela's design skills, of course. Mark simply emphasized a low drag fuselage shape over a fuselage shape that would land well. He might make a different design compromise next time. Daryl came very close to not making the flyoffs and then finished something like 6th in the flyoffs rather than winning because he kept shooting 95 landings with his Supras. Daryl also notched his horizontal stabilizers to fit partially around the vertical fin so that he could move them farther aft for better elevator control authority on landing.

[John Walter]

Phil:

I couldn't agree more. Clearly the Supra fuse is made more for flying than landing. Since I tend not to fly in contests, that is a good trade-off from my perspective.

[Kiesling]

You can overcome a design deficiency with enough piloting skill. That's not a dig at Mark Drela's design skills, of course. Mark simply emphasized a low drag fuselage shape over a fuselage shape that would land well. He might make a different design compromise next time. Daryl came very close to not making the flyoffs and then finished something like 6th in the flyoffs rather than winning because he kept shooting 95 landings with his Supras. Daryl also notched his horizontal stabilizers to fit partially around the vertical fin so that he could move them farther aft for better elevator control authority on landing.

Actually, Mark's fuselage design is fine. It is Vladimir's modification of the original that is the problem. It is a larger diameter that requires a very steep landing angle to keep the molded Supra from "squirting" through the landing area. This is the reason I elected to fly my bagged models with Mark's original fuselage design in the World Championships in Martin versus the molded Supra. The original design sticks at a much shallower angle.

As far as the stabs go, I can't comment on the molded model since I have always used my own (even on the molded version I had) which are slightly bigger.

Tom

[dhauch]

Hey Tom,
This is one of Mike Lakowski's Supra 130 pods, is this the same shape as your talking about ?

Just thought I would post a pic so they can see the difference.

dave
www.rc-builds.com

[Kiesling]

It is closer, but I think Mike made his a little bit bigger. Mike's F3B model uses the pod that I use. Unfortunately I don't have a Kennedy Supra fuse anymore so I can't take a picture showing the differences. But I know that mine is notably shorter and smaller in diameter.

Tom

[mlachow]

The pod that Tom and Mark use was designed for my F3B model. It is 2" diameter at the largest point. It is also at least 1" shorter on the nose, maybe a little more. The nose cone is designed for laminar flow and it does a good job even underground. I have never had a fuselage that sticks in the ground better than that one.

The Supra fuselage and the other "Supra" pod that I make will bounce and slide more. They are a little longer and on the vertical axis, both are higher. The shape hurts you a little of you are too shallow. In addition, the longer nose is getting to the point where fuselage flex will do things on harder landings.

The other thing about the Supra fuselage is the pod shape with a thin boom. If you do manage land at a shallow angle with speed, you don't have the bottom of the fuselage to provide drag on the ground.

For landing settings,I use a curve on my ailerons. The first part of stick travel brings everything down. But the rest of the travel eventually brings it up to a crow setup.

[lesterpk]

No problems landing a Supra here, 100 points ten of twelve rounds at F3J WC's.
I have some stick time on a Perfect and find it a little easier to control and land, but ehSupra just flies so much better for me.

You do need to adapt to landing the Supra a little more aggressively than some other models to get it to 'stick'.

Also, I did have the crawl mode set up, but got rid of it after a day flying it, didnt like it at all.

Les.

[analucius]

Wow. This is the first time I have hear a concern about the ability of a Supra to slow for landing. I certainly didn't hear that from any Supra flyers at the F3J WC this summer.

I started flying my Supra with less than max brake deflektion. I experienced a very low brake effect. I was puzzled.

Until I compared my brake deflection with a fellow Supra flier's deflection. It dawned on me why there is an indent for the tail-boom in the flaps. The flaps need to go all the way down on each side of the tailboom.

As soon as this was fixed I experienced stopping power comparable to my lightest DLG glider which is phenomenal in this department.

So make sure you have enough deflection. And you will find that the Supra slows more and faster than any plane you have seen.

Just my five cents.

Morten E - DK

[markdrela]

So make sure you have enough deflection. And you will find that the Supra slows more and faster than any plane you have seen. It's important to understand the distinction between deceleration and flying slowly. Deceleration requires high CD, which is maximum with the "brake" setting. Flying slowly requires high CL, which is maximum with the "crawl" setting.
I normally fly most of the approach in the crawl setting, and give only occasional blips of the brake setting to dump energy as needed.

[loic_debisschop]

No problems landing a Supra here, 100 points ten of twelve rounds at F3J WC's.
I have some stick time on a Perfect and find it a little easier to control and land, but ehSupra just flies so much better for me.

You do need to adapt to landing the Supra a little more aggressively than some other models to get it to 'stick'.

Also, I did have the crawl mode set up, but got rid of it after a day flying it, didnt like it at all.

Les.

That resuts are pretty amazing considering the conditions at the WC: no wind to moderate winds with gusts, obstacles such as tents and trees in the approach, and hard slippery bouncing ground ! :eek:
I saw in another thread that DP and JW were complaining about the poor landing results they had in Turkey. I don't know if they consider the supra harder to land... But i'm now glad to see that someone lands very well with the supra ! :D
How do you land the supra ? Do you prefer a fast or a slow approach ? High or low ? Do you have any particular setting or trick for the landing ?

Loïc (supra fan)

[nuevo]

looks like Vladimir's been listening. He's drawn up new Supra nose cones:

http://www.airplane-model.com/

[lesterpk]

That resuts are pretty amazing considering the conditions at the WC: no wind to moderate winds with gusts, obstacles such as tents and trees in the approach, and hard slippery bouncing ground ! :eek:
I saw in another thread that DP and JW were complaining about the poor landing results they had in Turkey. I don't know if they consider the supra harder to land... But i'm now glad to see that someone lands very well with the supra ! :D
How do you land the supra ? Do you prefer a fast or a slow approach ? High or low ? Do you have any particular setting or trick for the landing ?

Loïc (supra fan)

Whoops, got that wrong, it was actually 9 of 12 rounds, the others were 2 95's and 1 90. I did find the landing conditions at the WC's a bit challenging with the shortened approach and the traffic I wasn't used to but obviously I adapted well ;-)
I had no real plan except to not be late, I aimed for 1-2 seconds early to play safe during the prelim rounds. Some approaches were high and some low depending on traffic, one even included a quick 360 under full crow after hitting a huge thermal about 20m out from the spot about 10 seconds before the end of the slot. Poor Joe was probably having fits at my consistency of timing but I always got it on the spot on time.

I think the biggest difference in conditions to what I normally fly here in NZ is that the grass was much shorter, and you had to dork it in a bit to ensure you didn't slide through. I normally hate dorking my models but such is life. So I would generally end the approach about waist high, with a small amount of speed on to avoid being blown around, my radio setup for the Supra has as much down elevator as I can physically get so I can jab the model down to the spot.

Crow settings are nothing unusual, about 70 degrees flap, maybe a bit less up aileron than 'normal' and once the flap stick moves down 3-4 clicks then my ail>rud mix is doubled. Works for me.

Les.

PS - another NZer, Sven Zaalberg got eleven 100's in the prelims and another 6 of 7 in the flyoffs, he flew both Supra and Perfects.

[Kiesling]

So I would generally end the approach about waist high, with a small amount of speed on to avoid being blown around . . .

This is the same approach Arend Borst uses to land his Supra. Sticking it from waist high is a consistent way of keeping the molded Supra from sliding.

Tom

[loic_debisschop]

So I would generally end the approach about waist high, with a small amount of speed on to avoid being blown around, my radio setup for the Supra has as much down elevator as I can physically get so I can jab the model down to the spot.

I flew my supra yesterday, mainly for landing training. Thank to your answer i had a closer look to my elevator travel. I realized that my servo travel was limited to 100%. When the flap are full deployed, the elevator compensation is almost 50% (down). So there is only 50% stroke left for pitch down when the flaps are deployed ! :eek:
I just had to increase the servo limit to 150%, so i can get 100% stroke even with full crow. Works better like this :rolleyes: Thanks ! ;)