LAZY J's modified Baby Blender - build

[LAZY J]

*CAUTION - THE BUILDER MAY (UNLIKELY) OR MAY NOT (QUITE LIKELY) KNOW WHAT HE'S DOING*

So here's my build log for the Baby Blender with a list of mods for those who may like to follow along. I will be sure to share any tips or tricks I come find along the way.

This build is my very first foam board build and a test for a list of building and finishing experiments before I go all out on the FT Seaduck that sits next in my queue.

So list of objectives for this one:

1. Build it light by removing all paper from any internal or non critical areas whilst also staying away from the hot glue gun by using PVA and Gorilla glue for the build.

2. Try both covering film (wings and tail surfaces) and spray paint (fuselage) over a polyurethane sealing coat to compare the results in appearance and weight. Also test a bunch of methods for improving the general ruggedness of the airframe.

3. Move away from the faceted FT aerofoil design with a smooth rounded aerofoil section. Also add dihedral to the lower wing for some added stability, add individual aileron servos (maybe) and rounded tips to all flying surfaces for more of a vintage look.

4. Add central cabane struts, flying wires and replace foam board wing strut assemblies with something a little more "scale".

5. Add a suitably characterful pilot figure and move the rearward servo forward. Then the forward cockpit will be faired over to make this BB into a single seater (may go with a vintage race plane look for this one).

6. Add a more scale undercarriage (gotta throw in some cool wheel pants too!) alongside a bunch of additional scale like bling that takes my fancy.

7. Fixed, non removable and lightened motor pod with ESC mounted below for a little more airflow.


So that's the goals for now.... improve flying manners, make it look great AND keep it light.... how hard can it be?!


So here we go with the Flite Test speed build kit - a lot of the kit will be replaced/chopped up but it's good to support the FT crew. Also there is a C size power pack, 9 x 4.5 prop, and a 4S 2200mah 50c lipo (will maiden on a 3S 1300mah) to throw into the mix.

 

[LAZY J]

The first part of the build revolved around the fuse, tail feathers and motor pod...

 

[LAZY J]

Next step was making a start on the wings - unlike the fuselage the wings components (bar the spar) were cut from scratch to allow for the rounded aerofoil section as below.

Originally I was planning to add individual servos in each wing but the wing is a touch on the thin side. I am still considering putting two servos side by side in the centre section to add the ability for snap flaps, landing/low speed flaps and differential aileron though.

TIPS

1. In hindsight, if I were to do this again, I would scratch build the lower spar as a one piece item taking into account the dihedral and not worrying about the balsa and foam centre dihedral brace.

2. Pulling the paper off one side of the foam board will cause the foam to "curl" so store it flat with something suitably heavy on top and while building keep it taped/weighted down.... my procedure during the build was to start by sanding a 30 or 45 degree bevel in the leading edge, tape the leading edge hard down against the table (not doing this will likely result in a nearly symmetrical aerofoil section) and then using Gorilla glue bonded the upper skin at the leading edge and the spar. Once the skin was in place I then weighed the skin down with several magazines. When dry I then glued the bevelled trailing edge (more on that later) down once again making sure the lower surface was hard flat against my table.

3. I found the angle that you bevel your leading edge will have an effect on the final aerofoil section - sanding the join at 45 degrees will likely give you a semi symmetrical aerofoil and 30 degrees will give you closer to a flat bottom section. I chose to go for a semi symmetrical upper wing and flatter bottom lower hoping this will allow for the upper wing to lose lift sooner then the lower improving stall characteristics and maybe giving a little better inverted performance... the maiden will tell all

4. Electrical tape is great for taping foam board together during assembly - just tacky enough to hold components but not quite enough to pull the paper from the board. Also running electrical tape along either side of any Gorilla glue join will prevent it from making a mess of your foamboard. Once the glue hardens cut away the excess and peel the tape away and you're done.

4. Peeling the paper off one side of your foam board will save near enough to a third of the weight - in removing the paper as mentioned on this build 50 grams was saved (not a huge deal but is the same weight as one of the wings!).

5. If you do choose to make a rounded aerofoil make sure you extend your upper skin at the trailing edge or it will end short of the trailing edge ( I required an additional 12mm).

 

[LAZY J]

One last post before I get back to building is for those who can't make a straight bevel with a razor blade to save themselves (like me!).

A bit of scrap timber (in my case pine) and two grades of sandpaper (coarse and fine) glued to either side makes for a very handy tool.

As below it makes for good clean edges using the foam board's paper (as the elevator and rudder below) or masking tape (as the wing trailing edge below) as a sanding guide. Just a few light passes with the coarse side stopping when the paper/tape is contacted and a final light pass with the fine side is all that is needed.

Also is a great tool for cleaning out any foam left in your B fold channels with little fuss.

May be old knowledge to some but could come in handy for the foam noobs like me

 

[Morgan]

Looks great ! I have never but a baby blender and will look forward to seeing how it flies. ☺

 

[Daniel Kezar]

looks cool. have you flown it yet? if so, i was wondering if the baby blender would be a good beginner/intermediate plane. i have decent flying skills from simulator practice and such, i just haven't flown a lot. so with real flight experience i have only flown the ft flyer once but it i think i flew it well. i only crashed because i didn't build it well. the wings folded and the gear fell apart leading to me breaking both props that are in the power pack b.
so do you think it would be a good plane for me? think of it as a 5th or 6th plane, not my second. lol.

 

[AkimboGlueGuns]

Looking good! I absolutely love the Baby Blender. It's pretty squirely in the wind, but the dihedral you're putting in might take some of that out. The smooth airfoil also looks great the way you did it. Keep us updated!

 

[Michael9865]

Looking Great!

 

[LAZY J]

Thanks Morgan - that makes two of us!

Daniel Kazar - although I haven't flown a Baby Blender I definitely wouldn't recommend it for an entry level airframe. The build is a little harder than the FT Flyer (any biplane needs to be built well and true) and from everything I have seen online plus looking at the short coupled airframe up close it all adds up to something that, although fun, could still be considered a handful.... saying that though, compared to a standard balsa build or even an ARF, these are an extremely cheap and easy way to go. Build a couple of spares, take some glue, tape and spare props to the field, expect that they may have a short life and have fun learning.

Michael - thank you! Really enjoying the build... easy, fun and great way to wind down for an hour or two each afternoon.

AkimboGlueGuns - thanks and yes am hoping I can tame her down a touch. With the dihedral added, the smooth aerfoil and a few other changes I have in store I think she should make for a fine flyer.

 

[LAZY J]

Made a little progress over the last few days with the wing lightened and rounded tips added. Total weight savings added up to 22 grams bringing the entire weight saving program up to over 70 grams (approx. 2.5oz). Combined with avoiding the hot glue gun a low wing loading should be on the cards... a gram here and a gram there adds up quite quickly

Now with a final detail sanding she'll be ready for covering.

A few points, ideas and general ramblings:

- In hindsight I really should have added the rounded tips and cut outs to the original cutting of the wing templates. I also probably could have added quite a bit more dihedral (currently 20mm) but will see how this works out first.
- Even with the cut outs this wing is still VERY strong. I also tried cut outs in the rounded tips but the result of cutting the first showed an extreme weakening of the material (glued back in and the idea was promptly abandoned).
- Although the cut outs have an obvious effect on total flying weight/wing loading/stall speed the added advantage is moving more of the airframe's total mass inboard. Combined with the dihedral, aerofoil change, slightly increased wing area and rounded tips (trailing edge is slightly raised giving a lower AOA) it should, in theory at least, slightly improve flying manners in the roll axis and greatly improve the stalling characteristics.... now I need a little laydown before coming up with some ideas to improve her on the pitch axis!

Lastly was fabricating a one piece upper cowl/fuse/turtle deck cover. This was accomplished by first taking the time to tape the original card covers together, fitting them to the fuse and then carefully marking and trimming to give a nice clean template to cut out a replacement as seen in the below (this little BB will be a single seater as mentioned earlier).

 

[FoamyDM]

The build looks superb.

 

[LAZY J]

Thanks FoamyDM - really loving foam board building

 

[LAZY J]

A little more progress on the BB build with the undercarriage now mostly done.

The wheels were made with the bottom of four cans (a couple of extras may have been emptied "just in case"... possibly slowing progress just a touch ), some crack fill foam rod and a couple of black balloons.

The original plan was to glue the foam rod together and to colour with a sharpie.... this came undone when not one of the multitude of soft glues I pulled out would bond the ends of the rod. I then also realised the various brands of sharpies and paint I had on hand just rubbed off whatever mystery material this rod was made of?!

A bit of head scratching and some helpful collaboration with my 6 mates (all called Jack strangely enough) came up with this eventual successful combination of materials:



To solve the gluing issue I found poking the end of the rod several times with a thin wire created a solid mechanical bond for the Gorilla glue (squeezing the rod, applying the glue then releasing the rod will a few times will draw the glue into the holes). Then the inside of suitably sized roll of tape was used to hold the ends together while they dried. A little carving and sanding of the join then produced close to a seamless join.



Giving up on the original failed plan of colouring the rod I simply cut the ends off a couple of Balloons to fit snuggly over the foam tire. Then the bottom of four cans were removed with scissors followed by a final finishing sand with a metal file. The tire was then sandwiched between the two cans and bonded using Devcom metal epoxy. This was then clamped tight and left to dry overnight.

*TIP - the tire, when sandwiched by the wheel halves, will likely develop a bit of positive air pressure by the sealed in air trapped between the can halves and the rubber. This will prevent the can halves touching and bonding successfully. This is solved simply by pinching the tire and releasing the pressure. Also I would recommend half inflating the balloons first making them a little easier to stretch over the foam tire.

Once dry the centre of the rim was then drilled to accept a small diameter aluminium tube epoxied in place to carry the axle (will be trimmed to final size once the wheels pants are made).

The undercarriage was bent out of 2mm music wire, then the joins wrapped with copper strands (pulled from scrap speaker wire) and finally soldered:



All in all I am super happy with the final result and am sure it will add a great deal of character to the finished build. The tires are super light at 10 grams a piece. Also by using thin and light weight 2mm wire for the undercarriage the final combined weight is pretty close to what was originally intended and far sturdier.

Next I will add some "structure" to the bare wire frame and narrow the undercarriage to get the right look by cutting a measured section from the width to be then be rejoined using aluminium tubing and metal epoxy. This will also allow the addition of an aluminium aerofoil shaped tube over the u/c cross bar (not otherwise possible with the undercarriage soldered the way I wanted).

Here's a rough mock up of where we are at now

 

[rockyboy]

Love the wheels!

 

[foamtest]

Wow, those wheels are great! I may have to try those on some of my larger builds...

 

[Robyle3]

Hello! I just got done on a scratchbuild based heavily on a pt-17. After i buy myself some more foamboard ill have to give your build ideas a go. One idea i had to modify the ft wing was to cut the tip at a 45degree angle off the vertical. Because of the faceted wing this would also give the illusion of a rounded tip.

Your idea for the tires is genius!

If you have some pics of the finished build i’d love to see them, im half drooling envisioning all your mods in my head