I mentioned that my HK Slick had become something of a hanger queen this is due to one reason; the relatively tricky post stall handling.
There was speculation a while back about why the HK Slick is prone to wing drop out of harrier when planes from the likes of EF and 3DHS are a lot more harrier friendly. My personal theory is that the shape of the wing airfoil is the issue; the HK Slick has a very sharp leading edge at the root but the leading edge is far more rounded at the tip. This is old school wisdom to prevent tip stall, however the modern trend with 3D planes is a sharp leading edge root to tip so that the wing has a more definite stall, and once stalled stays stalled, this improves post stall stability.

So i decided to do something to see if my theory was right......

Here's the tip airfoil of the HK Slick:


And here is the SFG of a EF Edge EXP to show how the LE of the Edge is far sharper:


So I did some woodworking:


Template to shape new LE:


New LE vs. original airfoil:


Finished:


So i'll let you know what difference it makes, if any, fingers crossed

Steve

Originally Posted by JetPlaneFlyer

I mentioned that my HK Slick had become something of a hanger queen this is due to one reason; the relatively tricky post stall handling.
There was speculation a while back about why the HK Slick is prone to wing drop out of harrier when planes from the likes of EF and 3DHS are a lot more harrier friendly. My personal theory is that the shape of the wing airfoil is the issue; the HK Slick has a very sharp leading edge at the root but the leading edge is far more rounded at the tip. This is old school wisdom to prevent tip stall, however the modern trend with 3D planes is a sharp leading edge root to tip so that the wing has a more definite stall, and once stalled stays stalled, this improves post stall stability

WOW! This is going to be interesting! I was looking at an AJ Slick the other day and reflected over how similar they are and why they didn't copy the airfoil when they copied virtually everything else. I'm eagerly awaiting the outcome of this!

Originally Posted by JetPlaneFlyer

I mentioned that my HK Slick had become something of a hanger queen this is due to one reason; the relatively tricky post stall handling.
There was speculation a while back about why the HK Slick is prone to wing drop out of harrier when planes from the likes of EF and 3DHS are a lot more harrier friendly. My personal theory is that the shape of the wing airfoil is the issue; the HK Slick has a very sharp leading edge at the root but the leading edge is far more rounded at the tip. This is old school wisdom to prevent tip stall, however the modern trend with 3D planes is a sharp leading edge root to tip so that the wing has a more definite stall, and once stalled stays stalled, this improves post stall stability.

So i decided to do something to see if my theory was right......

Here's the tip airfoil of the HK Slick:


And here is the SFG of a EF Edge EXP to show how the LE of the Edge is far sharper:


So I did some woodworking:


Template to shape new LE:


New LE vs. original airfoil:


Finished:


So i'll let you know what difference it makes, if any, fingers crossed

Steve

Wow, way too much effort but I like it! I actually am eager to hear your findings...
I wonder also why they didn't copy the airfoil, AJ's airfoil design was one of the rants and raves when the AJ slick was first released! Surprised the HK clowns didn't realize this when they were "making improvements" to aj's design that they "never saw.."

Yeah, I'm looking forward to seeing what difference it makes. i also need to swap the motor out as the 6s installation i've got in at the moment is a bit heavy for slow 3D stuff (due to the batteries i have available). So I'll drop in the Scorpion.

If it works i'll shoot a video, just dont expect anything fancy. Even with the EF Edge (the 3D cheater) my skill level is only good enough for no frills harrier flight.. But i guess that makes me the ideal test pilot because if I can harrier the HK Slick then anyone can

Here's the Slick looking non the worse for the surgery:

Originally Posted by JetPlaneFlyer

Yeah, I'm looking forward to seeing what difference it makes. i also need to swap the motor out as the 6s installation i've got in at the moment is a bit heavy for slow 3D stuff (due to the batteries i have available). So I'll drop in the Scorpion.

If it works i'll shoot a video, just dont expect anything fancy. Even with the EF Edge (the 3D cheater) my skill level is only good enough for no frills harrier flight.. But i guess that makes me the ideal test pilot because if I can harrier the HK Slick then anyone can

Here's the Slick looking non the worse for the surgery:

That's true, if you can keep steady harriers, you very well may have modded your plane to be much better. Honestly if it wasn't for the crappy post stall characteristics, this plane would be a lot more fun to fly!

Just ordered my slick.should be here Wednesday. Gonna use the same setup as in the video at the beginning of the thread i think.

I just spent the last our reading the posts since friday.....and jees.Why don't we rename this thread to EF vs 3dhs vs HK....Sure some valid points were made,but I really have still not ad that "terrible" wing rock and wing drop"...
Steve I'm interested in your conversion to see what it does.No offense to anyone but the last 3 pages have been completely OT!

cool , i got 6 flights thru mine and i must be going too quick for the stall thats spoken of , will watch this mod with interest , my hk katana 1500mm has a horrendous wing stall , maybe this my help that too

Originally Posted by chop stiX

I just spent the last our reading the posts since friday.....and jees.Why don't we rename this thread to EF vs 3dhs vs HK....Sure some valid points were made,but I really have still not ad that "terrible" wing rock and wing drop"...
Steve I'm interested in your conversion to see what it does.No offense to anyone but the last 3 pages have been completely OT!

I don't know what kind of skills you have so I can't comment on why you haven't experienced the wing drop or rock, but the past 3 pages have mostly been those of us who owned the HK slick and other quality 3d frames giving our honest opinions. I'm the farthest from a follower, and tried the HK before I made any comments. I have reccomended the HK Slick to a few guys, but they werent shooting for 3d performance. To say the HK slick performed like the competitors would be an ignorant coment on my behalf. Naturaly when you own the product, you try to convince yourself the plane is better than it really is, I really wanted to love this plane and it's price, but sad to say it just wasnt the case. Combine that with HK's shady business ethics, and you get the last 3 pages. You can say what you want, but if our comments weren't accurate, why would this gentleman be wasting so much time to shave off the leading edge of his wing? I just can't reccomend this plane to anyone who wants to progress in 3d. It will just put you farther away from getting into a quality frame that will make you a better 3d pilot!
You may not necessarily agree with everything, but it would be a mistake to dismiss what we're saying, unless you wanted to try it out for yourself for experimental purposes like gyro and I.. The "We told you so" will be here whenever you're ready... Remember, these observations aren't from one or two people, they are from dozens of us who experimented with this plane. I really hoped we found a great alternative to the AJ slick, but sadly, we just didn't!

Originally Posted by UCDme3D

I don't know what kind of skills you have so I can't comment on why you haven't experienced the wing drop or rock, but the past 3 pages have mostly been those of us who owned the HK slick and other quality 3d frames giving our honest opinions. I'm the farthest from a follower, and tried the HK before I made any comments. I have reccomended the HK Slick to a few guys, but they werent shooting for 3d performance. To say the HK slick performed like the competitors would be an ignorant coment on my behalf. Naturaly when you own the product, you try to convince yourself the plane is better than it really is, I really wanted to love this plane and it's price, but sad to say it just wasnt the case. Combine that with HK's shady business ethics, and you get the last 3 pages. You can say what you want, but if our comments weren't accurate, why would this gentleman be wasting so much time to shave off the leading edge of his wing? I just can't reccomend this plane to anyone who wants to progress in 3d. It will just put you farther away from getting into a quality frame that will make you a better 3d pilot!
You may not necessarily agree with everything, but it would be a mistake to dismiss what we're saying, unless you wanted to try it out for yourself for experimental purposes like gyro and I.. The "We told you so" will be here whenever you're ready... Remember, these observations aren't from one or two people, they are from dozens of us who experimented with this plane. I really hoped we found a great alternative to the AJ slick, but sadly, we just didn't!

UCDme3D, he's stuck with HK and PA because he lives in South Africa, and EF and 3DHS aren't affordable/available there... So the HK slick may be the "best" plane he can get his hands on, hence his visible annoyance with the objective comparisons we have made.
I think maybe it's easier mentally "force" yourself to love what you have, than to constantly want something you can't get?

Originally Posted by -= GYRO =-

UCDme3D, he's stuck with HK and PA because he lives in South Africa, and EF and 3DHS aren't affordable/available there... So the HK slick may be the "best" plane he can get his hands on, hence his visible annoyance with the objective comparisons we have made.
I think maybe it's easier mentally "force" yourself to love what you have, than to constantly want something you can't get?

I see... Understandable, but the objective comparisons should not be written off. Whenever I'm about to get a plane, I look for posts just like ours that would prevent me from making a mistake. The overseas argument is absolutely valid, sometimes you're just in the wrong place at the wrong time.
'Merica!

I've been lurking here for a while. I found the last three pages very informative. I already ordered an HK Slick, but all the comparisons will be helpful in figuring out what plane to buy next.

Originally Posted by fishboy77

I've been lurking here for a while. I found the last three pages very informative. I already ordered an HK Slick, but all the comparisons will be helpful in figuring out what plane to buy next.

That's what this is all about!

Originally Posted by JetPlaneFlyer

...So i decided to do something to see if my theory was right......

Really great idea Steve!
I know from my days in sailplane competition that the shape of an airfoil is a tricky business and very small details in the shape can make it all.
I'm lookin forward to the results.

Originally Posted by peter24

Just ordered my slick.should be here Wednesday. Gonna use the same setup as in the video at the beginning of the thread i think.

If that is the one in the video claiming to be using the NTM Prop Drive 35-48 900KV I wouldn't go there.. 900kv is way too high to spin the 14" prop he said he used. Look for a motor 175-200g and about 750kv to run on 4s with a 14" prop