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NEXT LEVEL P-40 Group Build

BATTLEAXE

Well-known member
#42
You can easily build the speed wing with the under cambered wing tips. Just extend the bottom wing surface the distance of the ailerons plus half and inch. When you do a test fold over of the wing you can see where the 2 trailing edges meet and trim the excess. Bevel the 2 trailing edges (excluding the top cambered tips) as you do for a speed wing build. You can refer to Nerdnic video posted above and watch him build the speed wing to get ideas.

Hope that all makes sense.

I was going to do this for my FT Goblin but opted to keep that part simple as I did different mods.
I am going to watch his P-39 vid front to back again to get all the tricks down. That's a really good suggestion and in my head I was thinking that's what I was going to have to do, just not how to go about it. Like yours I am looking to build a plane that is capable of some decent speeds and still do some lofty slower passes like a Spit. I want to be able to streamline this as much as possible and every little bit counts.

Doing the double up folded tail feathers adds more weight to the tail, how do you compensate for the balance on that or is it even a concern?
I had a feeling that Hai-Lee would step in out of the vapor, with the Technical expertise and Answers, that I just wasn't capable of on this subject!! 😜😎 He's a wealth of information and a true expert in RC Flight!! 👍👍

@Sero That Video just gave ME a mind boggling amount of ideas!!! 😲😎
First, I forgot that Nerdnic's NNP-39 is FULL size, not Mini!!

Second, I'm adopting HIS method of double FB TEs and Tail Feathers!! SO much cleaner and more Scale! 👍👍
I'll still figure out a way to still incorporate Undercambered Wings, with that method....
..... Like @bracesport - that deep step in the lower Wing really messes with my Fengshui!!! 😜 That, and it actually can cause some Vortex Effects under the Ailerons. That's not where I'd want swirling, turbulent Air!!

YES, there's Hundreds of Thousands of FT Aircraft flying with that step....
It just messes with my limited knowledge of Aircraft Wing Aerodynamics.

And Third, did hear him correctly?? PURCHASE and QUICK BUILD KITS for his P-39???? 😮😁😎🍺🍺!!!!
OMFG!! I'm so IN on that. 😊

I'll be applying several of his appearance, performance and strengthening ideas in my P-40, and even my Storch!! 😎👋👋👋👋
There is a wealth of info coming out of this thread, very impressed so far. And I am sure there is more to come. I pm'd @Hai-Lee to check it out and get his input on it, and he came up all spades on this. So happy he is around to help... like I said before, he is like Yoda. The step transition from the bottom panel to the under camber tips half way along the length of the aileron is something that I don't think I will be able to get away from unless the LE of the aileron is two different thickness's, so those little vortex's will be present between the TE of the bottom panel and the underside of the aileron flap on the inner half... another thinker. Another reason I need to watch the P-39 vid.
The bigger Rudder is more fun:)
Do you tend to fly with a lot of rudder or is it just nice to have when you need it?

My Spit was a AET 3 channel and so i never used it there and I barely use it on my 4 channels although I am tending to use it more as I get better in flying skills and more daring as well.
 

PoorManRC

Well-known member
#44
I am going to watch his P-39 vid front to back again to get all the tricks down. That's a really good suggestion and in my head I was thinking that's what I was going to have to do, just not how to go about it. Like yours I am looking to build a plane that is capable of some decent speeds and still do some lofty slower passes like a Spit. I want to be able to streamline this as much as possible and every little bit counts.

Doing the double up folded tail feathers adds more weight to the tail, how do you compensate for the balance on that or is it even a concern?

There is a wealth of info coming out of this thread, very impressed so far. And I am sure there is more to come. I pm'd @Hai-Lee to check it out and get his input on it, and he came up all spades on this. So happy he is around to help... like I said before, he is like Yoda. The step transition from the bottom panel to the under camber tips half way along the length of the aileron is something that I don't think I will be able to get away from unless the LE of the aileron is two different thickness's, so those little vortex's will be present between the TE of the bottom panel and the underside of the aileron flap on the inner half... another thinker. Another reason I need to watch the P-39 vid.

Do you tend to fly with a lot of rudder or is it just nice to have when you need it?

My Spit was a AET 3 channel and so i never used it there and I barely use it on my 4 channels although I am tending to use it more as I get better in flying skills and more daring as well.
He IS Yoda! MALO!!! (LMAO scrambled Yoda style!) 😋😜

At your Level, I'd definitely say WATCH Nerdnic's Videos and study his posts here, CLOSELY!!
His TEs and all Control Surfaces are ALL Double thick Foamboard - both sides shallow Beveled into a SINGLE Point!! 😲😎👍👍

I'll be using SEVERAL of his tricks, because the P-39 and P-40 are VERY similar Airframes. Balancing shouldn't be a huge issue with some Common Sense!
I also believe that he is the MASTER of the Top Hatch Battery Mounts.

If Bob is Yoda... Nic is Obi Wan!!! 😂😉

And it's really nice that you get so many COMMENTS on your Threads! Extra helpful...
 

BATTLEAXE

Well-known member
#46
He IS Yoda! MALO!!! (LMAO scrambled Yoda style!) 😋😜

At your Level, I'd definitely say WATCH Nerdnic's Videos and study his posts here, CLOSELY!!
His TEs and all Control Surfaces are ALL Double thick Foamboard - both sides shallow Beveled into a SINGLE Point!! 😲😎👍👍

I'll be using SEVERAL of his tricks, because the P-39 and P-40 are VERY similar Airframes. Balancing shouldn't be a huge issue with some Common Sense!
I also believe that he is the MASTER of the Top Hatch Battery Mounts.

If Bob is Yoda... Nic is Obi Wan!!! 😂😉
I have seen a couple of his vids before and he has definitely inspired a couple of my ideas for kids, this old dog still learns tricks lol
 

Hai-Lee

Old and Bold RC PILOT
#47
I am going to watch his P-39 vid front to back again to get all the tricks down. That's a really good suggestion and in my head I was thinking that's what I was going to have to do, just not how to go about it. Like yours I am looking to build a plane that is capable of some decent speeds and still do some lofty slower passes like a Spit. I want to be able to streamline this as much as possible and every little bit counts.

Doing the double up folded tail feathers adds more weight to the tail, how do you compensate for the balance on that or is it even a concern?

There is a wealth of info coming out of this thread, very impressed so far. And I am sure there is more to come. I pm'd @Hai-Lee to check it out and get his input on it, and he came up all spades on this. So happy he is around to help... like I said before, he is like Yoda. The step transition from the bottom panel to the under camber tips half way along the length of the aileron is something that I don't think I will be able to get away from unless the LE of the aileron is two different thickness's, so those little vortex's will be present between the TE of the bottom panel and the underside of the aileron flap on the inner half... another thinker. Another reason I need to watch the P-39 vid.

Do you tend to fly with a lot of rudder or is it just nice to have when you need it?

My Spit was a AET 3 channel and so i never used it there and I barely use it on my 4 channels although I am tending to use it more as I get better in flying skills and more daring as well.
Firstly I will like to remind you that the step on the TE underside at the rear of the bottom sheet does not add much drag and that the airflow does not even see it as a step. This is the same as when using KFM wings where they have steps top and bottom because air is trapped in the step and circulates in the step area causing the majority of the airflow to flow over the wing as if it was a true and smooth airfoil shape.

Whilst you can see the step the airflow cannot do sudden right angle turns and a vacuum also cannot exist and so the air fills the gaps and the airflow is smoothed. It works equally well where your wing has a hole in it or is creased rather badly.

As for a double thickness rudder you can go 2 separate ways! You can remove one of the internal layers of paper and have a central hinge line, (beveled on both sides), remove the outside paper as well to really lighten the weight significantly , or have no internal paper and use a double thickness side hinged rudder of a standard type hinge.

For general flying you do not need a rudder at all as long as you do not fit undercarriage. To go without a functional rudder you MUST use the correct thrust angles for the motor as you will have nothing to combat the effects of a bad thrust line.

To cover the undercambered wing tips, (to smooth the airflow over the undercamber), you can add extra bits of FB, (with the added weight), you can use iron on covering film, (see balsa/Foamboard Spitfire), or you can use packing tape fitted carefully to evaluate any performance change without lots of extra work and expense. To allow the packing tape to be removable I seal/minwax the FB first so that the glue on the tape does not penetrate into the paper fibres of the paper causing the paper to be damaged when the tape is removed!

If you cover the wing tip underside I would suggest that you consider adding functional flaps. They do not need to be full deflection, (50 plus degrees) but rather a modest 15 to 30 degrees would make a massive difference and with such a modest flap angle you could use lighter servos, (<4 gram), and still have quite slow and controlled landings.If you are good at the IRONING you could extend the wing underside panel for the flaps and iron it down in thickness to have short cord flaps that will fit into the contour of the wing underside with only a little extra work. They would of course be small cord split flaps!

Have fun!
 

PoorManRC

Well-known member
#48
I have seen a couple of his vids before and he has definitely inspired a couple of my ideas for kids, this old dog still learns tricks lol
THIS Old Dog is always learning...
It's when we STOP, that we stagnate, and basically Die.

No, not all my ideas are AMA accepted.... I'm an "outsider" from the word GO!
But I'm enjoying myself, win or lose. I just try my best not to let People steal my Thunder! 😉

My Aviation Background is unique, to say the least... but a lot of it comes from some People who are considered Legends in the Industry - and several others who know WAY MORE than I ever will......

My entire FliteTest journey is an experiment!! 😉
 

Sero

Well-known member
#51
I know there is rudder input but I am sure there is some aileron to counteract the continuous roll right
Each plane is different, but you will need some down elevator to compensate for lift. Also often the faster you go the more effective your rudder will be so it can be easier to do.
 

Sero

Well-known member
#54
My thoughts on a few things:

I agree the step on the underside of the trailing edge doesn't add a lot of drag, but the faster you go the more drag it will have. It all adds up. Of course if your using cambered wing tips they provide the most drag on the wing. See volume #4 here. As Hai-Lee pointed out the the turbulent air is trapped but the step and TE and the laminar slides over it. But Battleaxe your TE is almost 90 degrees to that step and it wont really trap that turbulent air IMO. Its become one big flat TE.
One of the benefits you also get is your control surfaces will be far more rigid, less prone to flex or warping. which helps when going fast but also help with longevity. One of my planes all the control surfaces for some reason warped, it trimmed out but created a ton of drag.

One of the reasons I use feathered/airfoiled double sheet V and H stabs is they are more durable and less prone to flex. I had a flimsy fin on a plane and at high speeds it got a good flutter going. I don't feel it has any aerodynamic advantages to a single sheet, especially if you iron the edges .

Pictured below is my Mustang so you have a visual reference. It has a speed wing, weighs 750 grams without the battery and a 700 watt motor. I put flaps on it as at one location I fly I don't have a lot of room to land. this plane is slippery and with its weight it will glide a long way. I initially set the landing flaps to 40-45 degrees and it didn't help. If I pitched the nose up to try creating more drag it would just lift up and stall. i put the flaps to 50 degrees and it was perfect. My thought was my first setting didn't create enough drag and and too much lift, especially near the ground effect, although it seemed a bit high for that. You have to play around, each plane is different. The club i fly at has a 500' runway, so no issues there, usually dont use flaps.

IMG_20190403_094107.jpg

IMG_20180817_202149.jpg
 

BATTLEAXE

Well-known member
#55
My thoughts on a few things:

I agree the step on the underside of the trailing edge doesn't add a lot of drag, but the faster you go the more drag it will have. It all adds up. Of course if your using cambered wing tips they provide the most drag on the wing. See volume #4 here. As Hai-Lee pointed out the the turbulent air is trapped but the step and TE and the laminar slides over it. But Battleaxe your TE is almost 90 degrees to that step and it wont really trap that turbulent air IMO. Its become one big flat TE.
One of the benefits you also get is your control surfaces will be far more rigid, less prone to flex or warping. which helps when going fast but also help with longevity. One of my planes all the control surfaces for some reason warped, it trimmed out but created a ton of drag.

One of the reasons I use feathered/airfoiled double sheet V and H stabs is they are more durable and less prone to flex. I had a flimsy fin on a plane and at high speeds it got a good flutter going. I don't feel it has any aerodynamic advantages to a single sheet, especially if you iron the edges .

Pictured below is my Mustang so you have a visual reference. It has a speed wing, weighs 750 grams without the battery and a 700 watt motor. I put flaps on it as at one location I fly I don't have a lot of room to land. this plane is slippery and with its weight it will glide a long way. I initially set the landing flaps to 40-45 degrees and it didn't help. If I pitched the nose up to try creating more drag it would just lift up and stall. i put the flaps to 50 degrees and it was perfect. My thought was my first setting didn't create enough drag and and too much lift, especially near the ground effect, although it seemed a bit high for that. You have to play around, each plane is different. The club i fly at has a 500' runway, so no issues there, usually dont use flaps.

View attachment 141980

View attachment 141981
I see you are using flaps but no landing gear, I'm guessing there isn't an issue with the flaps dragging on the ground at all being that the under wing vent helps. And are those split flaps? And it also looks like you use Master Airscrew props, What's your thoughts on those?

I am trying to figure if the advantage for the under camber tips out weighs the aerodynamic gains of a speed wing like what you are sowing me and what I have seen nn build. I did watch a couple of his vids today, the one you posted and a speed wing specific build vid, and his Mig 3 maiden. Seems the drag of the under camber is more of an disadvantage then the gains of reducing tip stall. Maybe its just that I haven't flown a speed wing yet. If i build one what should I expect?

@Headbang is not a big fan of warbirds so I have an idea of what he will say, actually he told me to build a Mig 3 lol, so it's hard to tell lol.

I see you have Canadian roundels on you Stang as well, where do you live?
 

Headbang

Well-known member
#56
I see you are using flaps but no landing gear, I'm guessing there isn't an issue with the flaps dragging on the ground at all being that the under wing vent helps. And are those split flaps? And it also looks like you use Master Airscrew props, What's your thoughts on those?

I am trying to figure if the advantage for the under camber tips out weighs the aerodynamic gains of a speed wing like what you are sowing me and what I have seen nn build. I did watch a couple of his vids today, the one you posted and a speed wing specific build vid, and his Mig 3 maiden. Seems the drag of the under camber is more of an disadvantage then the gains of reducing tip stall. Maybe its just that I haven't flown a speed wing yet. If i build one what should I expect?

@Headbang is not a big fan of warbirds so I have an idea of what he will say, actually he told me to build a Mig 3 lol, so it's hard to tell lol.

I see you have Canadian roundels on you Stang as well, where do you live?
Speed wing is great for speed, also makes for hotter landings. Ft designed wings are more trainer like. Still plenty of speed to get trouble. My thoughts for my personal preference, there is never enough speed and I have yet to fly a plane that felt fast. Others tell me my planes are fast, but obviously they are slower then then my max ability to handle them. That said, next person would take the x-29 out and be overwhelmed with its speed. If you want speed think plank, that 3d printed northern pike has potential if I put a better motor on it (and rebuilt it). I have flown the ready made rc goblin at over 240kph, it was approaching something that felt fast. Nerdnic designs have potential as well. If you took his speed wing and put it on a fuse with less drag it would scream.
 

BATTLEAXE

Well-known member
#57
Speed wing is great for speed, also makes for hotter landings. Ft designed wings are more trainer like. Still plenty of speed to get trouble. My thoughts for my personal preference, there is never enough speed and I have yet to fly a plane that felt fast. Others tell me my planes are fast, but obviously they are slower then then my max ability to handle them. That said, next person would take the x-29 out and be overwhelmed with its speed. If you want speed think plank, that 3d printed northern pike has potential if I put a better motor on it (and rebuilt it). I have flown the ready made rc goblin at over 240kph, it was approaching something that felt fast. Nerdnic designs have potential as well. If you took his speed wing and put it on a fuse with less drag it would scream.
Ok cool. I will go with more of a speed wing then. It will be easier to build instead of trying to do a hybrid of both styles. If I stuck to the original wing it would be more like the Spit and I kinda want to go a different direction with it. I should probably do flaps as well then. Thanks for the feedback.

I looked into your Mig 3 vids. 9 months ago. Have you flown one since?
 

Hai-Lee

Old and Bold RC PILOT
#58
Just a note on TEs themselves. Yes a square cut TE will have a layer of circulating air trapped by the airflow over the wing and of course as this air is dragged forward there is a little extra drag, (caused by a partial vacuum/loss of pressure). So you might think that a sharp TE would be better but sadly a sharp TE can cause not only extra drag but also forces which can cause extreme flutter inducing forces, At the rear of the wing the air travelling over the top of the wing meets the air flowing under the wing! Unfortunately the airflows are travelling in different directions and at different speeds. The sharpness of the edge can make the meeting of airflows not only more sudden but also a little more violent because the cushion effect of the trapped circulating air is markedly reduced.

IF the knife edge TE is flexible at all, the tangle of air at the TE can cause the TE to deflect and even buffet, leading to massive a massive amd rapid build up of flutter.

As with most things it is a matter of compromise! If you make the TE too large a step you get more drag but a far more stable aerodynamic performance whereas if you lower the drag by thinning down the TE step the aerodynamic pressures work more aggressively against the wing TE rather than the circulating air trapped at the TE. As speeds go up so do all of the aerodynamic forces Drag and the TE turbulent airflow.

I agree with narrowing the TE on speed birds but past the 100mph I start to look more for rigidity than for that nice sharp TE!

Just a few thoughts!

have fun!
 

kilroy07

Well-known member
#59
Doing the double up folded tail feathers adds more weight to the tail, how do you compensate for the balance on that or is it even a concern?
Do you have dollar generals around you?
They have a tri-fold foamboard school presentation board that is 3mm. Double that up and your still pretty close to the standard width/weight.
On my night-flight Corsair (Casper) I used a double tail, I think that MS design really needs a redesign in the tail.
I used regular dtfb and did it so I could hide an LED strip inside. After I had Casper all together and flying I found that trifold board. 🙄

Knife edge is something I gotta work on. I haven't figured out what inputs holds the maneuver yet
You and me both! 😂
Each plane is different, but you will need some down elevator to compensate for lift. Also often the faster you go the more effective your rudder will be so it can be easier to do.
Yeah - surprisingly a lot. At least on the planes I fly...
I LOVE these little segue ways/bits of knowledge! Thanks both for the tips, I was using up rudder and she kept rolling out... now I know why! (And knowing is half the battle!)
 

BATTLEAXE

Well-known member
#60
Just a note on TEs themselves. Yes a square cut TE will have a layer of circulating air trapped by the airflow over the wing and of course as this air is dragged forward there is a little extra drag, (caused by a partial vacuum/loss of pressure). So you might think that a sharp TE would be better but sadly a sharp TE can cause not only extra drag but also forces which can cause extreme flutter inducing forces, At the rear of the wing the air travelling over the top of the wing meets the air flowing under the wing! Unfortunately the airflows are travelling in different directions and at different speeds. The sharpness of the edge can make the meeting of airflows not only more sudden but also a little more violent because the cushion effect of the trapped circulating air is markedly reduced.

IF the knife edge TE is flexible at all, the tangle of air at the TE can cause the TE to deflect and even buffet, leading to massive a massive amd rapid build up of flutter.

As with most things it is a matter of compromise! If you make the TE too large a step you get more drag but a far more stable aerodynamic performance whereas if you lower the drag by thinning down the TE step the aerodynamic pressures work more aggressively against the wing TE rather than the circulating air trapped at the TE. As speeds go up so do all of the aerodynamic forces Drag and the TE turbulent airflow.

I agree with narrowing the TE on speed birds but past the 100mph I start to look more for rigidity than for that nice sharp TE!

Just a few thoughts!

have fun!
Thank you very Much @Hai-Lee, you must be reading my mind. I was trying to decide how to execute the TE on a speed wing, sharp or thicker and rounded off. Sharp would be more difficult to manufacture and now like you said counter productive. And like @kilroy07 said the 2 layers laminating together I may taper slightly to make just a bit more then one layer thick and iron rounded for strength and creating that air cushion, which makes more sense, and will be easier to fabricate. Added bonus it makes it easier to incorporate ailerons and flaps. Thank you again.
Do you have dollar generals around you?
They have a tri-fold foamboard school presentation board that is 3mm. Double that up and your still pretty close to the standard width/weight.
On my night-flight Corsair (Casper) I used a double tail, I think that MS design really needs a redesign in the tail.
I used regular dtfb and did it so I could hide an LED strip inside. After I had Casper all together and flying I found that trifold board. 🙄


You and me both! 😂


I LOVE these little segue ways/bits of knowledge! Thanks both for the tips, I was using up rudder and she kept rolling out... now I know why! (And knowing is half the battle!)
I know right, who would have thought of down elevator on their own. I was doing the rudder input which made sense but i was trying to compensate for roll with the ailerons. Down elevator... have to remember that...:unsure: