Pond Skipper

Well its time to start another one, I have been icthing to use a TD .09 engine next!
Instead of the ply rolled design like the 1/8A Lil Speedy and 1/2A Skorch I wanted a fuselage that could
lay on its side at slow speeds and knife edge around with swagger that sits so well in the air smoooth as butter!
A egg shell design will provide great side surface area and so Lil Miss Butter Knife will grow from this build thread a real sweety of proven design.

In the 1990's I had scratch built a 82in span big bird concept that could have stunt type plane flying with rock steady knife edge flight at slower than normal speeds of the day. It proved to be ahead of its time as a outdoor slow flight plane as a big bird / powered by a OS 40 FP the sleek and light balsa skinned plane could still rip through the air at plus 50 mph. The plane won a few awards during big bird fly in's for a unique concept that was able to do so much with just a 40 size engine rather than the typical use of gas and large 2 stroke glow engines.

Later a smaller faster version was flown with a OS .25 with equal good fun and breath taking verticals with its scale lines mimicking something that could have been
a full scale plane in the 1950's.

In order to slow things down and keep things light the design needs to be a 15 size plane flown with a low weight TD .09.
I have explored the basic lines with my typical drawing efforts shown here is the basic look and size dimensions thus far.
The second pic has the doodle blown up on a 32in screen which allowed up to 27in in length close enough to the target of 29in.
I wanted to make sure the 09 had enough space in the nose to work and to insure I have enough surface area the fuselage
gained some weight.

hllywdb

Looks a bit like an astro hog

combatpigg

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This is definitely something different and I'm sure will be most interesting to follow.

Pond Skipper

Heres some pics of the 82" span OS 40 FP design and one of ye ol Astro Hog for comparison.


Taken back in 1993 - 22yrs ago

Pond Skipper

Here is the smaller version OS 25 FP

Note the big bird has a full () shape egg shell this version has some flat tops built back in 1997.
Still rather large for the engine size the foam balsa sheeted wings and balsa fuselage kept things light 3/16th balsa formers.

combatpigg

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Now I see what you mean by egg shell. That's a very nice looking birdo..!

Big and light.

I messed with a DIY 3D profile project, LA .40, 11 x 4 or 11 x 3 and the Mousse Can Pipe shown at "Spad To The Bone" website. The pipe is ugly, but it really boosted the power.

Pond Skipper

The concept worked so well I built the largest version to date powered by a Zenoah 26 gas engine first flown in 1995
I wanted a vintage mono plane look with plug in wings and a masive side profile for gobs of life when on its side.
The weight would typically be 18 to 20lbs for a plane this big the balsa and light ply plane came out tad over 10 ish lbs.
It could enter into slow inverted flat spins like a full scale plane and knife edge at a tad under half throttle almost unlimited vertical
by appearance around 80 degs to cheat it out of sight.

combatpigg

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That's a really neat looking gasser. A very rare sight around here, but if I drive 20 miles to the north or to the south-east that is the majority of what you see.
I think knowing how and where to go with minimum structure on a model this size and weight would need to come from a certain amount of failures or close calls. This is where having competitions comes in handy for everyone. The competitors will do the dirty work to find how skimpy a certain scale can be built. Not so with kit manufacturers, until I came across the Goldberg Ultimate .60 sized. That's a pretty big plane to come out at 9.5 pounds with a 1.20 FS glow engine. It was reported to be capable of KE loops, but not by me. I'd do the first 270 degrees, then bail out.

Pond Skipper

Yes depending on design you can get away with many things. I had used 26, 56, and .80 size 4cy engines then jumped up to the 26cc at the time of the build.
Despite the large size the plane could bolt about like a it had a 42cc engine on the nose and a floater on landings that had enough mass to carry down the flight line to a soft landing.

I made an attempt to blow up the pic of the 40FP plane showing the nose up attitude at this angle the throttle could be backed off quite a bit,
the overall size of the beast is quite a site and treat to fly.

Tee Bee

I'll be watching this one as well. I haven't built anything new in a couple of years and have been thinking lately that an .09 project might get me motivated again.

Pond Skipper

Thank you Tee Bee, posting the concept plane now has me committed to making it happen lol.

This one will be big and light but very sleek with a fish shape fuselage allowing it to move through the air with relative ease. What should be
a .15 size plane is estimated to hit my aggressive target weight of 17oz.

For the elliptical wing I plan to use two sheets of 1/8 balsa with carbon sq stock to create a natural airfoil.
The center section will have a thin ply skin top and bottom like the 1/2A Skorch. To keep the speed up a ply strip will be laminated
between the two balsa sheets to create a sharp leading edge and to protect it from dings. The tail feathers will be fully symmetrical
airfoils for maximum control without the need to overthrow the surfaces. Will order the rest of the parts online and head over to the local
hobby store this week for the wood. Shown in the pic is the 4mm x 4mm carbon square stock, something that really wasn't around for
most of us in the 90's more so aluminum and fiberglass / now common stock item in hobby stores.
In the foreground is my choice of wheels not sure which one to use as of yet...

Lol jk the Williams Brothers 5in wheels weight 5.15oz ea. I will go with them in the 1.5 in size if the weight is reasonable.

Pond Skipper

For the vibration and power of the TD .09 I went ahead and bought 3 of these online tonight;

Hitec HS-A5076HB Digital Slim Karbonite Gear Servo

High impact karbonite Gears with ball bearings
Uses rubber grommets for vibration protection
Torque @ 4.8V: 2.5 kg-cm (34.7 oz-in)
@ 6.0V: 3.0 kg-cm (41.7 oz-in)
Weight: 14.3g (0.5oz)




I like that they are slim and wont eat up room may be the ticket to ride for future projects too.
So Elevator / Rudder and Ailerons will have 42oz of torque to work with and 1 HS-45HB for the throttle.

Looks like 1.5in wheels will be rolling on this plane, thin low drag with enough rubber to hold up
on rough landings.

BMatthews

That sketch and cuteness just pouring out of it.

To enhance the slow speed knife edging idea I'd suggest the deeper looking first version. And perhaps even go for a upright or inverted inline engine look to the nose to get more side area. With the shortness of the nose and the pointed look there's just a bad balance of side area with MOST of it being behind the expected CG point. for good knife edge flying you want to still have about 25% of the total side area, including fin and rudder, ahead of the CG. Much less than 20% and it gets tough to have enough rudder to hold it.

Pond Skipper

Thank you very kind of you to say!

Yes will have an upright engine as shown in the drawing also for spot on idle less risk of loading up.
The 82in span version had a inverted engine but can't risk that with a throttle sleeve on the 09. The plane size with the 29in fuselage really is more a .15 size plane so I should have enough surface area than the norm. You may have noticed the long tail moment this allows for additional authority to hold the nose up. The other plus is the low mass to size the fuselage is a lifting body with a very tapered back end the tear drop shape should dynamically move the CG rearward in motion. The plane needs to have a pointed nose and () shape for penetration being a large plane for power out all sneaky tricks to max out the top end will help lower the total reynolds number. Should be interesting the smaller 25 size engine pulled the 40 size plane around with ease being all balsa. I will be pushing the weight limit using ply skin but want to make a long lasting plane showing off a lot of wood grain. There will be a brushed aluminum engine half cowl over and sticky back brushed aluminum around the open cockpit with leather piping with fake button for some scale charm lil bit of dash work with Bridgette in the pilot seat. Brushed aluminum sticky back covers over the wheel hubs.Same aluminum tape used for AC duct work. Should make for a keeper never to be sold off.

189.6g / 6.69 oz

- Engine / prop
- RX
- 4 servos
- 2 oz round sullivan tank
- engine mount

Known weights goal 17oz - 10.31 oz left to work with.

Pond Skipper

Reworked the doodle with the engine at full size to find the actual numbers and size of the plane.
It came out to 27.25" tail to spinner tip with the CG at 9.5" from tip of the spinner so 65% / 35% split taper wing set the CG with blue dot.
Next will work on a clean fine line rendering with formers so I can transfer to cardboard templates.
Then work up a full size wing and elevator / horizontal stab.

MJD

My Feedback: (1)

Nicely done. Are you a Kinner Sportster fan by any chance..? All you need is a 5 x .020 radial to cap it off!

Saw one of the only two flying examples at Geneseo 4-5 years ago.. it flies like a big rubber model with a small engine. Slow and stately and light on the wing, 40mph stall speed.

Pond Skipper

Yes Mike sweety of a vintage sport plane, in fact I watched a vid of a 1/4 scale with a working 5 cyl engine.
I could buy 5 Cox .020 glow plugs mounted to bass wood cylinders sprayed black or silver for a fake engine.

I had to do a search tonight for a 1.25in spinner a perfect size for the TD .09 so I had to buy from the far east.
The prop bolt for the 09 is a 6-32 I will have to make a adapter for what looks like a 2.5 or 3mm spinner bolt.

Pond Skipper

Ok had to buy another set of new wheels I was off in size and type had bought 1.5in Vintage what I really needed was 2in Golden Age.
Cleaned up the file further and added Bridgette and the 2in wheels.
Will use a aluminum landing gear and two nylon bolts to hold it to the underside of the wing.

MJD

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Have you looked at Brodak? They make Al spinners down to 1".

MJD

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Might be a bit too pointy..

http://brodak.com/brodak-1-1-4-spinn...h-2-holes.html

Pond Skipper

Thank you Mike,

Yea have seen them in the past they are a bit pointy for this design, does appear light weight and good quality perhaps I can source a prop adapter from the brodak site.

Pond Skipper

Looking at the fuselage parts count and layout:

- 4 1/4 inch spruce stringers
- Firewall 2 lams of 1/8th ply
- 5 1/8 th inch lite ply formers
- 1/8 th inch balsa cockpit floor and back
- Cherry wood dash
- Lite ply wing saddle doublers
- 2 thin sheet ply skin halfs

hllywdb

And then just wait for a day with no wind to fly it I like the floaters. My wife built a 99" Butterfly a couple of years back. I just set out a lawn chair for her and she motors around just above idle with an FP 25. Burns NO fuel too. It's cub yellow with big polka dots all over it LOL

Pond Skipper

Sounds like a nice relaxing day and a great way to get the wife out and joining in.
I never could get mine to join in the flying bit, more like a book reading moment under a shade tree while I fly at best.

This one does have a big side profile and has enough wing to putt putt abouts but lean like the 82in span plane, finished the formers easy enough.
The TD .09 engine good for peak bhp at 20K static 30% nitro with a wood 6x4 Zinger - per Peter Chinn's write up.
Perhaps with the modern APC 6.3 x 4 wide blade sport prop will have enough thrust for the 17 oz target weight. If unloaded at 22.5K 85.2 mph.

I have ran the TD 09 RC the throttle works great on muffler pressure. I want to see if I can get good response with the throttle sleeve being a larger engine it might be able to tick along slow passes inverted, knife edge or doing slow rolls with the option to do the tricks at a faster pace. If I can do away with the muffler for more pow wow.


For now here are the formers set up to graduate with a consistent taper which allows a full continuous sheet of thin ply per side without the need for splicing. I will use aluminum top cowl the soft stuff easy to form off the firewall and to the 1.25in spinner.

MJD

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You have a CNC cutter for those formers?

I still can't wrap my head around sheeting one side of the fuse with a single piece of ply, but I do see a fairly straight taper along the 9 and 3 o'clock axes. I believe it!