mrjdstewart
Legendary member
and no, the 2208 is for the cub. way to big for a mini. i can toss in a a-pack motor into the box as well for you.
me
me
My first three Trainer Builds - AND Modifications, because I'm not normal!!
- Thread starter PoorManRC
- Start date
PoorManRC
Master member
nice. I have a box of stuff for you as well. I have also built probably 10 diff cubs by this point as well. let me know if you need any help.
our club winter party is the 15th. you should really try and make it. it would be a good day to meet and intro you to everyone. I can also bring a buddy box and let you fly my radian glider. everyone should start with a glider in my opinion.
let me know how i can help.
me
Thanks Jason! As is the new normal with me..... That's very nice of you!!
I may need a Prop or 3.... I've got 6" for the Minis, and two 10" for the Storch. I think this calls for an 8"...
Maybe I could run the Cub with a 1045 Slo-Fly?? I don't know.
Starting out with a GLIDER???
I thought those long Winged Soarers were for the more advanced...I will HAVE to check my Schedule, and Checkbook. I'd really love to get with a Club. Gas across Town is too much sometimes... I want to!
I've basically been a Hermit for the past few Years. I was even worse after my Daughter was killed... Since 22 Oct 2016, I've really only left the house for food and Doctors.
I used to be a Social ANIMAL, even Lead a Band... So I shouldn't be a psychopath, (!!!!) I might be uncharacteristically Shy though.
I will DEFINITELY let you know!
PoorManRC
Master member
and no, the 2208 is for the cub. way too big for a mini. I can toss in a a-pack motor into the box as well for you.
me
Oh!! That's some of the stuff I'm still learning.... I thought it said 2815 on the package. I'll take a look.
How about on 2S... Could i run a 2208 on the TT with 2S?
...... I could use A Pack Motors for the Minis.
PoorManRC
Master member
Ya know Brother... I've heard worse ideas!!
Factor in the WEIGHT of the added Details, with dead weight. I like it!! 👍👍 And....... I'm Good at Math... My Dad used to do Algebraic Equations IN HIS HEAD!!! I'll never be that good. Quantum Mathmatics is why I never became an Aeronautical Engineer.
😫
PoorManRC
Master member
I can finally SHOW you something!!!!!
Not progress by most of your standards, but I've got a tough schedule and a horrible Budget.....
Here's the Mini Sportster.... Pre Built for me. Probably a better idea than it originally seemed, because these don't come with instructions (YES I know about the Videos!!!), so it was good to see just how these basically go together.
Couple of more angles.....
Even with this nice example, I STILL managed to SCREW UP my Mini Scout!!!
I made all the cuts correctly, scored the lines for the Camber well enough.... ran the Hot Glue, set the Wings up.....
THEN realized that I made them UPSIDE-DOWN!!! Yes, the seam is on TOP of the Wing, now a glue filled gap!
Well..... it's added weight AT the CoG, right?
I THINK it's going to be OK. Looks like a Wing, it's symmetrical. A couple of dents where I manhandled the Foam, but otherwise okay!
It's not easy to see, but this is going to be a feature on all of my Foamies.... rounded and/or bevelled Leading Edges and Tips.
PLEASE, before anybody says anything, I do realize that this may not add ANYTHING to the Performance of my Aircraft.....
I just prefer this to the flat or often concave Edges!!
Anyway, I AM Building things over here!!!
Not progress by most of your standards, but I've got a tough schedule and a horrible Budget.....
Here's the Mini Sportster.... Pre Built for me. Probably a better idea than it originally seemed, because these don't come with instructions (YES I know about the Videos!!!), so it was good to see just how these basically go together.
Couple of more angles.....
Even with this nice example, I STILL managed to SCREW UP my Mini Scout!!!
I made all the cuts correctly, scored the lines for the Camber well enough.... ran the Hot Glue, set the Wings up.....
THEN realized that I made them UPSIDE-DOWN!!!
Yes, the seam is on TOP of the Wing, now a glue filled gap! Well..... it's added weight AT the CoG, right?
I THINK it's going to be OK. Looks like a Wing, it's symmetrical. A couple of dents where I manhandled the Foam, but otherwise okay!
It's not easy to see, but this is going to be a feature on all of my Foamies.... rounded and/or bevelled Leading Edges and Tips.
PLEASE, before anybody says anything, I do realize that this may not add ANYTHING to the Performance of my Aircraft.....
I just prefer this to the flat or often concave Edges!!
Anyway, I AM Building things over here!!!
PoorManRC
Master member
More Mini Scout Build.....
The rest of this is going according to the plan. Except for the bevelling, this one is going to be a stock Build......
I'm also coating all bare Foam, especially at bevels, with White Gorilla Glue... It doesn't seem to add much weight, and it soaks into the Paper. This should NOT delaminate!!
A closer look at the rounded Edges (not quite finished), before the Glue coating.
BTW... THANK YOU @kilroy07 !!! That 3D Printed Bevel Razor Tool is a Life Saver!!! 👏👏👏👏👏👏 SO easy, and perfectly straight!
........ This "Quick Build" has been taking a back seat, to some Insanity!!
A Tiny Trainer!!!
The rest of this is going according to the plan. Except for the bevelling, this one is going to be a stock Build......
I'm also coating all bare Foam, especially at bevels, with White Gorilla Glue... It doesn't seem to add much weight, and it soaks into the Paper. This should NOT delaminate!!
A closer look at the rounded Edges (not quite finished), before the Glue coating.
BTW... THANK YOU @kilroy07 !!! That 3D Printed Bevel Razor Tool is a Life Saver!!! 👏👏👏👏👏👏
SO easy, and perfectly straight!........ This "Quick Build" has been taking a back seat, to some Insanity!!
A Tiny Trainer!!!
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PoorManRC
Master member
The Tiny Trainer......
A SMART noob would have just built this Stock. I apparently, couldn't! I've read a lot about this Trainer, and realized that as Designed, it's not quite a stable Training Aircraft. Stability is one of those things that inspire confidence - especially for a solo N00B!
I completely "Designed" a new Fuselage! Sort of taken from a Blog on the FT Website.... but crude.
2" Longer overall, mostly to increase the Tail Moment some. I also created a bit of a Cabin....
I also trimmed in about 4 Degrees of Main Wing Incidence. Also for more stability, especially at Takeoff and Landing!
I have built in 3 degrees of side Thrust, and 2 degrees of down Thrust.
Unlike possibly ALL of You, this has all been FREEHAND!!! I don't know CAD, I'm no architect, no training! Just playing on Decades of Aircraft Experience, and conversations with Guys MUCH smarter than Me!!
A SMART noob would have just built this Stock. I apparently, couldn't! I've read a lot about this Trainer, and realized that as Designed, it's not quite a stable Training Aircraft. Stability is one of those things that inspire confidence - especially for a solo N00B!
I completely "Designed" a new Fuselage! Sort of taken from a Blog on the FT Website.... but crude.
2" Longer overall, mostly to increase the Tail Moment some. I also created a bit of a Cabin....
I also trimmed in about 4 Degrees of Main Wing Incidence. Also for more stability, especially at Takeoff and Landing!
I have built in 3 degrees of side Thrust, and 2 degrees of down Thrust.
Unlike possibly ALL of You, this has all been FREEHAND!!! I don't know CAD, I'm no architect, no training! Just playing on Decades of Aircraft Experience, and conversations with Guys MUCH smarter than Me!!
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@PoorManRC
Instead of bevel cutting the edges to round them (which will weaken them and allow the paper to peel) maybe try using a clothes iron to melt them over. I have done this with several builds. When they are rounded over with heat from iron, the paper will close the rounded edge in and then you can "paint" over the edge with Elmer's School Glue to keep the paper from peeling.
The sealed edge will then take paint without melting the foam and ruining your edge.
Here is a Cub (Thanks Shaun Martin) that I built with this method.
Here is the link to the Cub if you like. It flies like butter...smooth!
https://forum.flitetest.com/index.php?threads/foamcub-swappable.9343/
So far your builds look fine to me. You may need to cut a bit more away on the Scout fuse where the wing gets inserted. With your fold, the wing will be just ever so slightly longer than the plan. Take a look at the Speedster below the wing. You can cut the bottom of the fuse and insert the wing. Then just glue the bottom back on. Saves crumpling the wing and fuse when trying to insert it otherwise.
Gazoo
Instead of bevel cutting the edges to round them (which will weaken them and allow the paper to peel) maybe try using a clothes iron to melt them over. I have done this with several builds. When they are rounded over with heat from iron, the paper will close the rounded edge in and then you can "paint" over the edge with Elmer's School Glue to keep the paper from peeling.
The sealed edge will then take paint without melting the foam and ruining your edge.
Here is a Cub (Thanks Shaun Martin) that I built with this method.
Here is the link to the Cub if you like. It flies like butter...smooth!
https://forum.flitetest.com/index.php?threads/foamcub-swappable.9343/
So far your builds look fine to me. You may need to cut a bit more away on the Scout fuse where the wing gets inserted. With your fold, the wing will be just ever so slightly longer than the plan. Take a look at the Speedster below the wing. You can cut the bottom of the fuse and insert the wing. Then just glue the bottom back on. Saves crumpling the wing and fuse when trying to insert it otherwise.
Gazoo
kilroy07
Legendary member
I've been looking for a different Cub to build and I think this one is it!!
Thanks for the heads up, and to ShaunMartin for a really nice article, plans AND build videos (great job man!)
I would say that 6 deg incidence on the wing is way to much. I'd use 2 deg on a plane like that plus at least 3 deg downthrust on the motor. I reckon that if you try and fly that plane with zero downthrust and 6 deg of incidence, it'll fly around with its nose in the air and waggling its tail like an eel, and whenever you open the throttle, it'll go vertical or try to loop. You might be able to keep it in the air if there's no wind.
I don't like to discourage anybody from trying anything. At least we learn what happens, but if you want it to fly nicely, you need to stick with established design principles.
I don't like to discourage anybody from trying anything. At least we learn what happens, but if you want it to fly nicely, you need to stick with established design principles.
I thought that about 3° was normal-ish. Just looking at it, it does not look like 6° to me. Were talking about the modified (blue) TT fuselage, right?
I was just looking at the TT plans and it looks like it has 0° incidence and I don't think that the TT that I built had any down thrust on the Power Pod.
I've got to be missing something. Can someone explain?
You need downthrust on just about any high wing plane when the motor is on the nose, especially one with dihedral.
Imagine a small boat gliding in a straight line through some water and then you put your hand over one side into the water to create some drag on that side. The boat will turn towards the side with drag.
It's exactly the same for an aeroplane. The most drag comes from the wings, some from the fuselage, some from the wheels and a tiny bit from the tail. On a plane like the TT without downthrust, the most drag is above the motor thrust line, so the motor will work like a pendelum and try to curve upwards, which results in the plane pitching up when you apply power. You can trim the plane to fly straight at half-throttle by adding in down-elevator trim, but when you reduce the throttle to land, the plane will dive because the engine isn't pulling up anymore, but the elevator is still trimmed down.
The idea is to install the motor with the thrust-line going through the centre of drag, which will prevent the plane changing its pitch when you change the throttle.
All this is slightly complicated on some planes by the vertical position of the C of G. If it's below the thrust-line, it'll cancel some of the pitching up, and if it's above, it'll make it worse. It's very difficult to calculate all these things, so, as a designer, you need a bit of experience to make a guesstimate or you can do some tests to see which angle you need to prevent pitch changing with the throttle.
Another reason for down-thrust is that a plane will naturally get more lift when it flies faster - even more so if the wing has a positive angle of incidence, so you can counter that with downthrust.
If you read many of the beginners accounts, you'll see how often they complain about this pitching up effect, which I say is because there's insufficient down-thrust. I reckon it's because FT didn’t think through their idea of swappable engine pods or they figured that the effect wasn't bad enoughto make more pod variiants.
Having the wrong down-thrust or side-thrust is not a deal breaker, but the plane will fly much better and be easier to fly if you get it correct.
Angle of incidence of the wing is basically the angle between the wing and the tail. If we draw a straight line through the tail along the fuselage, it's the angle that the wing makes with that. By wing, it means the datum line that runs through the cross-section, like this mauve line, not the bottom of the wing:
https://goo.gl/images/ENiVnf
As the angle of incidence increases, so do the lift and drag. You probably wouldn't notice much between zero and 2 degrees, but by the time you get to 6 deg, you'll have control problems on most normal RC aircraft.
Just to make it clear, everything I said above is with reference to the aircraft's datum line running through the tail. On some plans, they show an arbitrary datum line, and they might show a negative incidence on the tail with maybe no incidence on the wing, but it's the angle between them that counts. It's the same with down-thrust. I'm referring to it relative to the line that runs through or parallel to the tail.
Imagine a small boat gliding in a straight line through some water and then you put your hand over one side into the water to create some drag on that side. The boat will turn towards the side with drag.
It's exactly the same for an aeroplane. The most drag comes from the wings, some from the fuselage, some from the wheels and a tiny bit from the tail. On a plane like the TT without downthrust, the most drag is above the motor thrust line, so the motor will work like a pendelum and try to curve upwards, which results in the plane pitching up when you apply power. You can trim the plane to fly straight at half-throttle by adding in down-elevator trim, but when you reduce the throttle to land, the plane will dive because the engine isn't pulling up anymore, but the elevator is still trimmed down.
The idea is to install the motor with the thrust-line going through the centre of drag, which will prevent the plane changing its pitch when you change the throttle.
All this is slightly complicated on some planes by the vertical position of the C of G. If it's below the thrust-line, it'll cancel some of the pitching up, and if it's above, it'll make it worse. It's very difficult to calculate all these things, so, as a designer, you need a bit of experience to make a guesstimate or you can do some tests to see which angle you need to prevent pitch changing with the throttle.
Another reason for down-thrust is that a plane will naturally get more lift when it flies faster - even more so if the wing has a positive angle of incidence, so you can counter that with downthrust.
If you read many of the beginners accounts, you'll see how often they complain about this pitching up effect, which I say is because there's insufficient down-thrust. I reckon it's because FT didn’t think through their idea of swappable engine pods or they figured that the effect wasn't bad enoughto make more pod variiants.
Having the wrong down-thrust or side-thrust is not a deal breaker, but the plane will fly much better and be easier to fly if you get it correct.
Angle of incidence of the wing is basically the angle between the wing and the tail. If we draw a straight line through the tail along the fuselage, it's the angle that the wing makes with that. By wing, it means the datum line that runs through the cross-section, like this mauve line, not the bottom of the wing:
https://goo.gl/images/ENiVnf
As the angle of incidence increases, so do the lift and drag. You probably wouldn't notice much between zero and 2 degrees, but by the time you get to 6 deg, you'll have control problems on most normal RC aircraft.
Just to make it clear, everything I said above is with reference to the aircraft's datum line running through the tail. On some plans, they show an arbitrary datum line, and they might show a negative incidence on the tail with maybe no incidence on the wing, but it's the angle between them that counts. It's the same with down-thrust. I'm referring to it relative to the line that runs through or parallel to the tail.
Ahh... Thanks for the explanation. Makes sense. Because the wing is mounted so close to the thrust line on the TT (and even the Bloody Baron/others) then there is little need for down thrust. Higher wing planes will need more down thrust...as a general rule.
So, if it were a Spitfire or the like with a low wing design, the down thrust is inherent in the design. Just a little right thrust is needed...maybe.
High wing, floaty bush plane with tundra wheels...neutral down thrust?
So, if it were a Spitfire or the like with a low wing design, the down thrust is inherent in the design. Just a little right thrust is needed...maybe.
High wing, floaty bush plane with tundra wheels...neutral down thrust?
Hai-Lee
Old and Bold RC PILOT
If only it was so simple!
There are other things to consider. Firstly if the motor is mounted below the planes centre of mass there will be a tendency for the plane to pull its nose up when full throttle is applied. In this situation ideally the thrust line should be such that it passes through the centre of mass for neutral behavior.
Second thing to consider is that If the motor is mounted quite low in the plane the aerodynamic drag can "pull" against the upper portion of the plane, (mostly on high wing, Parasol, and Biplane installations), this drag with the motor producing significant thrust can again cause a tendency to nose up further as the plane speed increases.
Both of the above are dealt with through the application of a little down thrust.
In summary each and every design should be evaluated post build to ascertain the best down and side thrust angles.
Just a few thoughts!
Have fun!
Looks like you've got it. As long as you understand those basic principles, you'll be in the right ball park, but as HL says, you'll see whether you got it right when you do the first flight. With an understanding of what's going on, you can make the right adjustment if necessary.
PoorManRC
Master member
I probably wasn't clear enough, but I "painted" all of the exposed Foam Edges with White Gorilla Glue, for the same reasons you mentioned.
OH! As this has been entirely "hand built", I accidentally made the Wing Incidence closer to 3.7 degrees.
And I May not have mentioned, but I've got 3 degrees of down Thrust too....
I am very intrigued by that hot iron method, and am going to look at it now....
This WHOLE thing is a $1.00 experiment in DTFB!
PoorManRC
Master member
More on the Build....
Another thing I've heard is, the Wings BUCKLE under Loadll That might reduce the enjoyment somewhat.....
I Beefed up the Spar a bit, with some "stragically placed" popsicle sticks. I may put 2 more, going a little more outward on the Wing.
More weight? Yes - but at least it's situated around the CoG.
In a close up, you can see the beginning of an extreme Bevel I'm putting on the back of the Underside of the Wing. It's just been ROUGHED OUT, it will end up smoother!
I'm TRYING to eliminate the Step, which on 1:1 Aircraft, would cause a wicked Vortex at the back of the Wing!! Will it make a big difference? I DON'T KNOW! But I'm willing to try....
I also redesigned the Tailfin....
A bit Taller, to add some more Yaw Stability...
Don't believe me? Look at some of the almost comically Large Tailplanes on RAF Fighters!! An RAF Pilot once told me the same thing, Yaw Stability. Especially on the Fighter/Bomber version of the Typhoon. Makes for better Bomb aiming when using Iron Dumb Bombs.
Another thing I've heard is, the Wings BUCKLE under Loadll
That might reduce the enjoyment somewhat.....
I Beefed up the Spar a bit, with some "stragically placed" popsicle sticks. I may put 2 more, going a little more outward on the Wing.
More weight? Yes - but at least it's situated around the CoG.
In a close up, you can see the beginning of an extreme Bevel I'm putting on the back of the Underside of the Wing. It's just been ROUGHED OUT, it will end up smoother!
I'm TRYING to eliminate the Step, which on 1:1 Aircraft, would cause a wicked Vortex at the back of the Wing!! Will it make a big difference? I DON'T KNOW! But I'm willing to try....
I also redesigned the Tailfin....
A bit Taller, to add some more Yaw Stability...
Don't believe me? Look at some of the almost comically Large Tailplanes on RAF Fighters!! An RAF Pilot once told me the same thing, Yaw Stability. Especially on the Fighter/Bomber version of the Typhoon. Makes for better Bomb aiming when using Iron Dumb Bombs.
PoorManRC
Master member
I definitely understand that! Is 2 degrees of down Thrust going to be enough?
Hai-Lee
Old and Bold RC PILOT
In all honestly no one will know exactly as your build has varied from the standard build BUT as an estimate it will be a good starting point!
Have fun!
PoorManRC
Master member
Thank you Bob! I'm starting to second guess this whole thing.......
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