FT Bushwacker SLOW

[jakexie6]

Hey there folks! This is my second Bushwacker build as my first one only had 2 flights on it before it met its untimely demise. But this new one I want it to go slow. Really SLOW. So slow in fact that I designed leading edge slats for it along with mixing in my ailerons with my flaps for extra "flaperage". But in my conquest for ultimate crawl pace. I considered putting VG's (Vortex Generators) and endcaps as I've heard they will help prevent a stall. So with the endcaps, I can do that pretty easily as I've seen people do that before, but what about VG's? If it's even worth it where would I put the VG's? On the slats or on the leading edge of the wing as usual? Also, anything else I can do to get this thing at a snail's pace? I want to be dragging my tail wheel on the ground when I'm landing. I've always liked pushing things to the extreme.

 

[Hai-Lee]

If you want real slow you could change the flaps to double slotted flaps and the prop over to a large Dia Slow Fly. A little extra wing span would not go astray and of course lighten the HECK out of the fuselage.

At extremely slow speeds the tail loses it effect so the SF prop is to "Blow" the tail surfaces and of course the split flaps. Done properly you should be able to tether the plane and get it to lift off of the ground using the prop wash blown over the wing, slats and flaps.

Have Fun!

 

[jakexie6]

I've unfortunately already built the wing and fuse, so lengthening the wing isn't an option for me. But I haven't installed any servo's and I am intrigued by putting double slotted flaps on this plane. I've seen mechanisms for double slotted flaps online but they've seen heavy and complicated. Any other way? Also, about the slow fly prop, how big of a dia would that be? I plan on running a 10x4.7, if I need to run bigger, wouldn't I need a bigger motor along with it? Last question, should I bother with VG's?

 

[Hai-Lee]

I use a 10x4.7 on my rather heavy FB ugly stick being driven by a Park 480 on 3S It takes off and lands in under a metre but it could be better I suppose.

Split flaps could be done easy and without a huge weight increase if Balsa or a similar material was used. Perhaps even sheet plastic but then the weight would quickly escalate in order to get the strength of a properly treated balsa strip. If you were to make them extend rearwards as they extend and droop then you effective wing area would increase markedly To strengthen a strip of thin balsa I coat the strip all round with a thin layer of glue. It can be strengthened lengthwise by inlaying a strip of CF as well.

A simple slide mechanism for servo control could be made easily if you had access to a 3D printer or similar.

Just a few thoughts!

have fun!

 

[jakexie6]

Thanks! I have some cad experience so I'm jumping for the double slotted flap. Knowing the dimensions of the flap and everything I think I can cook something up in Fusion 360. If I get a working model I'll print them out and post the files as well. I've managed to do a single slotted flap but doing a double slotted. Well, that's tricky. Anyways thanks for all the help!

 

[Brett_N]

here's a couple things I tried on my 'wacker

1 - the leading edge slats DEFINITELY help slow down
2 - extend the length of the flaps - I did one wing that was full flaperon - if you have a programmable radio, this is fun
3 - increase the horizontal stabilizer - double the size of it.
4 - big slow fly prop

I also got the flap hinges from the multiplex funcub - these allow true "Barn door" 90 degree vertical flaps. Only way to go with split flaps

 

[Merv]

All good ideas, my 2¢, reduce wing loading by building light, use less hot glue, it's very heavy. One stick should build a plane. The other way to reduce wing loading is a bigger wing. Wings are fairly easy to build, do some experimenting with different size wings. I build 3 wings for my last project.

 

[Brett_N]

hmm.... that's it! a triple wing bushwacker!

 

[foamtest]

I was thinking of doing a similar thing to a storch, building extremely light and having fixed flaps so I can save even more weight. Also if you peel off all the paper and then cover the foam with thin packing tape it is extremely light and builds just as well. This is actually my winter project this year, along with a few other planes... and some ground RC stuff.

The list never ends does it?

 

[jakexie6]

Unfortunately, I've already built the wing and fuse so extending the wingspan or reducing hot glue isn't much of an option for me. What I am willing to do, however, is to design double slotted flaps for this plane. I think they are better than split flaps and I hope they will add to the "cool" factor of the airplane. I plan to keep the plane stock, but just to do a bunch of mods to it, so again the bigger stabilizer at the back is something I'm avoiding for now. (Hint, I'm lazy). And about the full-length flaps. I plan on mixing in a separate switch on my radio to lower my ailerons down to add to the effect of the flaps. This way I can fully deflect my flaps along with my ailerons! And I know I keep coming back to this point but what about VG's? Is it worth my time to make them or anything or should I just skip them?

 

[Brett_N]

go with the leading edge slats instead of VG's. Easier to build too.

 

[rockyboy]

Wow guys! Check out this in depth look at model scale vortex generators, complete with experiments and video results!

https://www.rcgroups.com/forums/sho...tex-Generator-Experimentation-and-Design-Tips

Very impressive work! I think I'll be trying these on a build in the near future too.

BUT

Don't need to bother reading past the first two pages of the thread - it devolves into nasty personal attacks and bickering and doesn't add any additional value in the other 16 pages

 

[d8veh]

My Hobbyzone Carbon Cub has them. It lies really nicely, but it does ha e quire a bit of drag and mames a lot of noise when going fast with no throttle. I can't say that the noise is definitely coming from the vgs, but I haven't head a noise like that on another plane. Despite all that, it has to be lne of the easiest planes to land.

 

[jakexie6]

If you want real slow you could change the flaps to double slotted flaps and the prop over to a large Dia Slow Fly. A little extra wing span would not go astray and of course lighten the HECK out of the fuselage.

At extremely slow speeds the tail loses it effect so the SF prop is to "Blow" the tail surfaces and of course the split flaps. Done properly you should be able to tether the plane and get it to lift off of the ground using the prop wash blown over the wing, slats and flaps.

Have Fun!

Made the double slotted flaps in Fusion 360. I have some general dimensions but any suggestions on what material to make the hinges out of?

 

[Hai-Lee]

Made the double slotted flaps in Fusion 360. I have some general dimensions but any suggestions on what material to make the hinges out of?

I would have 2 preferences firstly print them, or secondly a thin ply/balsa sandwich.

have fun!

 

[jakexie6]

I would have 2 preferences firstly print them, or secondly a thin ply/balsa sandwich.

have fun!

Good thing I just got some ABS filament from Hobbyking! Time to try these out!

 

[jakexie6]

After WAY too many hours working on this, the flaps are finished on the perfect day! Happy Thanksgiving y'all!

 

[rockyboy]

The mechanism and mechanics look good! You might find that the 1/2 way setting is actually the most you'll want to deploy, and a 1/4 setting will be a usefull one too. I don't know where I lost the link to it, but there are several aerodynamic studies that have identified the max flap deflection where it transitions from providing extra lift to only creating drag (both useful effects when used with purpose, but not fun to trigger by accident)

Happy flying!

 

[jakexie6]

The mechanism and mechanics look good! You might find that the 1/2 way setting is actually the most you'll want to deploy, and a 1/4 setting will be a usefull one too. I don't know where I lost the link to it, but there are several aerodynamic studies that have identified the max flap deflection where it transitions from providing extra lift to only creating drag (both useful effects when used with purpose, but not fun to trigger by accident)

Happy flying!

Thanks for the tip! I'll put the flaps on a knob so that I can find which setting produces most lift while I'm flying.

 

[rockyboy]

Thanks for the tip! I'll put the flaps on a knob so that I can find which setting produces most lift while I'm flying.

Excellent idea! Theory is good and all, but real world testing is best