FT Bushwacker BUILD

ProfessorFate

Active member
Hybrid Savage Bushwacker

1403p_stol_04_zps2oppwilc-1 lg.jpg
Right after I saw Localfiends 8th post with the Cub picture, I went searching, found the Zlin Savage Bobber.
The FT Bushwacker flies 3D almost like the Turbo Beaver from twisted hobbies.
2674553.jpg
Youtube vid of turbocrack beaver
I wanted this airplane but not out of those materials the beaver was made from or the light power system...TCBeaver and Bushwacker look very similar, but, the FTBushwacker is a much better choice.
To help build light but not with foam board, I found a way this might be done with the light dowels and a little light ply which is almost a gram per square inch. 1/8x12x48 Lite Ply 538.5grams per 576sqr.inches.
Good stuff and it's $10 / sheet on Amazon.

Here's a pic of a Savage Bobber sim to post 8, a combo in proportion of Bushwacker and Bobber where I shortened the cab height. The only paneling would be the front sides and bottom same size as FT Bushwacker planning for wing chord of 7inches also. These are the real panel dimensions.
SavageBushwacker lowcut w ruler.jpg SavageBushwacker lowcut plain w ruler.jpg

The inside stick detail and seats are not right, yet. But I like the open frame of the Bobber. I'll just paint them red or black.


If the plane picture missing the stick detail is not shrunk by the system, then, it is the same full size as the FT Bushwacker, the tail is just a littler smaller.
I'm trying real hard to make this work less than 24oz so this plane can 3D hover with the 70gram Suppo 2217/7 1250kv "Beef" motor. This will give about 37oz thrust with a gws 9x5 dd at 11.1v

If this does not work, comes out too heavy, there is a really super motor at Altitude Hobbies for just $23, 2814/6 1400kv a 100gram motor will give 68oz thrust with an APCe 9x6 on 3s.
Wish I had bought this motor first, it would make it easy on us if our planes get a little heavy.

Suppo 2814--6--1400kv Park480  for $23 -- 2.jpg

SavageBushwacker BLANK at stock H 9.jpg

Finally after looking more closely at the cut down profile, I restored it to the same height as the original FT Bushwacker and it may look better, this is it with a ruler too. The tail might be made bigger and the wood panel pattern is for both 7" or 8" chord wings. The drawing came with an 8" prop but you can see there is plenty of clearance for anything.

This might 3D really good with a fattened s5020 or NACA 20 airfoil. You can use Profili to generate airfoil patterns. Now I think I'm ready to cut wood.

3D airfoils s5020 naca 20 and 16 chord 7inch.jpg

Now here is some fun if you have ever used Real Flight Sim and put special airfoils on a funfly plane, then you have seen the fatter foils hold you in the air real easy, you can easily fly inverted without any dihedral.
The s5020 most resembles the foil FT makes with their DTFB wings.
NACA 16 is used on the Sig Somethin Extra 48" stunt plane, and that fatter NACA 20 might really fly slow and would give lots of controlled flight, no tip stalling. Thin wings stall first.

Clark Y 15.jpg

Feel I made a mistake recommending s5020 after seeing how thin it was. Look at this Clark Y 15 produced in Profili, fatter foils resist tip stall to a much greater degree. This looks much closer to the pattern the flat bottom lifting foils, cargo planes, Cubs, FT uses.

Notice the Bushwacker foil looks like this. Skinny foils tipstall, fat ones don't. The symmetrical foil will not produce Bernouli lift but will give the 3D performance you like and this fat Clark foil might come close, it will produce great lift. You could use either one of these fat ones probably without any dihedral, a straight wing.

I was thinking after making the Savage Bushwacker fuse, of making a wing with a lifting foil just about like the Clark Y 15. Playing with Real Flight Sim and a fun fly plane changing the airfoils and other attributes on planes really tells you a lot concerning changes you make and the foils behaviour.
I was wanting 3D performance and something that would make lift and float, I live in south Tx where we have thermals but flat land.

A big fat NACA 16, if you want strictly 3D, would let you put the plane exactly where you want it, the air grips it better, won't stall, wish you could try this on a sim and see "PropSpinner" constant chord would not bother this at all it's just not like a Spitfire with the thin elipse wing shape given to the tip stall. Now you try a NACA 20, that one should be extreme and slow. See the E flite Edge 540, the foil looks like a NACA 16.
E-Flite Edge 540 BP 3D Arf review pikks  23.jpg
 
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ProfessorFate

Active member
Where to buy Uhu Por link and Lite Ply too

I came across a post of where to get Uhu Por glue ( it is foam safe too ), Amazon link here, been looking for that stuff.
CraftyDan mentioned it makes the best glue hinge for your foam models if you have an hour to spare.

http://www.amazon.com/UHU-POR-Styrofoam-adhesive-tube/dp/B000LKOC1M

Even tho I have not built anything but a mold with it so far, I wanted some for foam constr.

Here's one for the above mentioned Lite Ply, I believe it is used in most kits and it's really good, about $10 per 1/8x12x48inch sheet. W=538.5g/576sq inch sheet, best deal I have found so far:

http://www.amazon.com/gp/product/B000BQYLNK?psc=1&redirect=true&ref_=oh_aui_detailpage_o03_s00


Maestro, in the Savage Bushwacker, it will have a flat bottom floor, I'm gonna put stops forming a box with 1 open side at the top, set the battery inside and I think run a velcro strap thru 2 slots to go around the battery. You could put a long strip of velcro on the battery and on the place where it goes as long as a strong dive would not pull it free, like if it were placed inside like mine. I want to strap mine in tho, it cost $40, don't want it falling out getting damaged. I know what you mean, they did not show those details or ideas about it, and how often do you also see their batts flying loose!

Leonard.
 
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Maestro

Junior Member
Putting the lipo in the nose in the bottom plate means its sort of jammed between the bottom plate and the power pod.
And it holds the lipo in place that way but I think it is not good for the bottom plate having that tension continuesly and second the lipo might get loose.

I ended up reinforcing the bottomplate a little bit with 2 sticks and used velcro strap so i can slide the lipo in and pull the strap.

Also I centered my wing servos and had the trailing edge even over the whole lenghte of the wing. When I put the rubber bands on it pulls down the middle section.. Do I keep it like this?

All else is done, hoping to get a maiden in coming weekend.. image1 (1).JPG image1.JPG
 

Torf

Senior Member
Also I centered my wing servos and had the trailing edge even over the whole lenghte of the wing. When I put the rubber bands on it pulls down the middle section.. Do I keep it like this?

All else is done, hoping to get a maiden in coming weekend.. View attachment 54722

Maestro, my Tiny Trainers do that same thing when the rubber bands are in place. All that is happening is that the trailing edge of the center of the wing is being pressed into the fuselage. The rest of the wing doesn't have that force applied, so it settles in a neutral attitude. The warp doesn't seem to have any effect, but I would make sure both sides are nearly identical in their warpage. A couple millimeters shouldn't matter, but if one side is way off from the other, investigate to make sure there is nothing protruding from the fuselage holding one askew.

Good luck on your maiden!
 

Corbarrad

Active member
Also I centered my wing servos and had the trailing edge even over the whole lenghte of the wing. When I put the rubber bands on it pulls down the middle section.. Do I keep it like this?

If you put your wing onto a flat surface and let it rest on its bottom plate, does the trailing edge lie flat on the table as well?

If the back of the wing is consistently off the table I'd probably just leave it as is even if the airfoil is off. The angle of incidence might be off between your wing and your horizontal stab with the trailing edge sticking up but you should still get lift. You might have to keep some up elevator even at the reccommended COG.

What follows is purely specualation on my part:

It kind of looks like the break in the wing behind the spar isn't fully formed. Check that the back portion of your wing is still glued to the back of the wing bottom plate. If it is, something is off with the geometry of the wing in general, maybe the bottom plate bent up to meet the top instead of the other way round.

I don't think there is anything you can do about it at this point unless the back of the wing is still loose, then you might be able to redo the score cut behind the box spar and form your air foil before gluing the trailing edge.

Preforming the wing is pretty important on these builds. Personally I'd push the wings a little more than needed rather than too little because the foam you crushed will try to re-expand and undo the curl. I also fold the leading edge completely over so it doesn't fight me as much during assembly.
 
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ProfessorFate

Active member
Wings deform, crush under the rubber bands?

If you leave the air void in the center, it will deform.
When you build your wing, why not just fill the areas where the rubber bands will fall, with some foam that won't crush down and you keep the nice shape of your wing. Try a piece of foam board insulation there or junk foam but some that will not crush under pressure.

Have yall seen the way EndOfTheRoadRC built his foam Fokker D7 biplane, he put foam ribs inside and bent the foam board around this. Look up his youtube construction videos. FokkerD7 EndOfTheRoadRC  1.jpg

When I see something really good, I make a kind of project description sheet with all the important details right there handy. Nice plane and video, thank you for sharing this EOTRC.
flight:
https://www.youtube.com/watch?v=b2BuX_3Kk3M
Constr vid wing:
https://www.youtube.com/watch?v=lcNfmq3F4so
 
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laury415

New member
Got to maiden it today. Really flew great. Very smooth, performs fantastic.

A couple things:

1) According to the instructions the CG is 1.75". At that point, the plane was definitely tail heavy. I added several oz. of weight in the nose to get the CG correct. When I flew it, I had to add a lot of up elevator trim which means it is now nose heavy. Next time I fly it, I'll take out the weights, but the question is regarding the CG, should it be at 1.75"? I think it should be further back based on the way this flies.

2) I set the plane up with Flaperons. I'm not real happy with that set up. When the flaperons are not engaged everything is fine. When I engage them, the plane banks drastically to the right. It is much harder to control, and even though the flaperons slow the plane down, it becomes too unstable to try landing. I'm going to switch this thing to conventional flaps and see if that is better. The wing is simple to rebuild, so if I don't like it I'll start over.
 

mactek

Member
Got to maiden it today. Really flew great. Very smooth, performs fantastic.

A couple things:

1) According to the instructions the CG is 1.75". At that point, the plane was definitely tail heavy. I added several oz. of weight in the nose to get the CG correct. When I flew it, I had to add a lot of up elevator trim which means it is now nose heavy. Next time I fly it, I'll take out the weights, but the question is regarding the CG, should it be at 1.75"? I think it should be further back based on the way this flies.

2) I set the plane up with Flaperons. I'm not real happy with that set up. When the flaperons are not engaged everything is fine. When I engage them, the plane banks drastically to the right. It is much harder to control, and even though the flaperons slow the plane down, it becomes too unstable to try landing. I'm going to switch this thing to conventional flaps and see if that is better. The wing is simple to rebuild, so if I don't like it I'll start over.

I started with flaperons also and did not like them at all. After the first couple of flights i added flaps and the plane is great. I personally think it flies much better with flaps. As for the CG i fly mine a little tail heavy i find it easier to hover the plane.
 

Hippy

Junior Member
!st off, Hello , I am new to this site. I ordered the FT Bushwacker & have started to build it but there is one part I cannot seem to identify. Can someone here help me out? Thanks 001.jpg
 

SP0NZ

FT CAD Gremlin
Staff member
Admin
Moderator
Mentor
Its the throw gage. You use it to check the deflection of your control surfaces. I'm not sure that Peter used it in his build video. Check out the end of some of the other build videos for reference. Basically, the flat part sits on the stationary surface, and you use your radio to move the control surface (ailerons, elevator, rudder) up to the angled surface.
 

Hippy

Junior Member
Its the throw gage. You use it to check the deflection of your control surfaces. I'm not sure that Peter used it in his build video. Check out the end of some of the other build videos for reference. Basically, the flat part sits on the stationary surface, and you use your radio to move the control surface (ailerons, elevator, rudder) up to the angled surface.

Than you! I kinda thought that but then I seemed to remember 16 degrees from the video & since there was no 16 on it, I wasn't sure.
Thanks again for your quick answer
 

mactek

Member
I did a quick patch job on the Bushwacker last night so i can fly it this morning. Last weekend i had an issue where the power pod came loose in the air and the motor ripped the front end apart. So i have permanently hot glued the powerpod in now and and with a little reinforcement got the front of the plane back together. This added a little weight but it should not be a problem. I am hoping to shoot some video this morning of the flight so i will post the results. I also did away with the foam board wheels as the wet grass in the mornings were not doing to well.

IMG_0049 copy.jpg
 

laury415

New member
So I pulled out the weights I had in the front nose, and added in flaps.

Plane flew great. I had the elevator trim centered and didn't need to add any trim at all, it was perfect. Also the flaps worked way better than the flapperons for slowing down the plane and still staying in control.

I did test where the CG should be with a 2200 3s battery installed and it was almost an inch further back then the directions at 2.75 inches back from the leading edge of the wing.
 

zyxstand

Junior Member
Need some input: I've built the bushwacker and put together all the parts, but it seems that the plane is very tail heavy (~3/4" - 1" behind specified 1.75" CG) with a 190g (6.7oz) battery (3s, 2200mAh). What actual CG will work? laury415, are you suggesting 2.75"? Note that I don't have flaps/flaperons.

I've never flown before (only practiced in a simulator) so I'd appreciate some noob-friendly advice with this CG problem.
 

rossmort

Member
Maidened with a DT750 and 10x4.5 prop (What I had laying around). It actually worked quite well. Barely enough to hover and no punch out. Still very fun. I wasn't able to dial in my high throw expo setting (It was wild on high throws!).

Similar experience with flaperons. I will probably convert to flaps, but was still able to slow down quite well. This is my first plane where I could taxi through the grass which was quite fun.

I do need to revamp my battery setup and do the velcro loop on page 7 of this thread. I can barely get the battery pushed forward before the velcro strip grabs and then getting it back out is a pain!