Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin  |  Contact Global Moderator
September 19, 2019, 12:05:43 AM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: [1]   Go Down
Print
Author Topic: Mr Smoothie P-nut  (Read 521 times)
0 Members and 1 Guest are viewing this topic.
BG
Platinum Member
******

Kudos: 83
Offline Offline

Canada Canada

Posts: 1,644


Topic starter
Me with F1B - epic retrieval (flew 10km after DT)


WWW

Ignore
« on: September 30, 2018, 10:38:43 AM »

Hi All,
I am working up my new Peanut scale Mr. Smoothie kit that I based on the Mike Isermann dime scale plan. in the following posts I will show the build as it progressed and talk about some of the details of the design and the kit.

First post: So here you see a picture of the kit as well as printed tissue. The wood in this case is 1.2 mm thick (about 1/20th") ... this wood was sold as 1/32 but I have noticed that some manufacturers do not actually cut 1/32 (0.8 mm) but rather sell 1.25 mm (1/20)under the 1/32 label.  This is good for my purposes because 1/20th is perfect for smaller models.
the lesson: if you really need 1/32 then check the thickness before you buy.

The strip in the kit were stripped from stiffer A grain 1/20.

The tissue you see is Jap tissue purchased from Volare and printed using an Epson printer with durabrite water and solvent (meaning dope thinners) proof pigments. The art was produced by me using Adobe illustrator and based on a detailed three view and photos in the Hirsch Volume and an Aeromodeller article.

The plan is by Mike Isermann and was obviously based on the Mendenhall 3V which happens to be a fairly inaccurate drawing of the Mr Smoothie racer. The well known Rees Mr Smoothie plan, and the Easy Built models kit are also based on this same 3 view.
The problems with the Mendenhall drawing are (see attached comparison between the blue Mendenhall drawing and the better Aeromodeller 3 View):
1. The wing shape (not enough taper).
2. Registration (wrong letter font)
3. Stab trailing edge shape is off.
4. The tail moment is too short
5. The stab is position too far back and low relative to the fin.
6. The upper air scoop is way too big (the photos of the aircraft show that the scoop was quite small; note the easy-built airscoop is even bigger, but it looks kinda cool.
7. The wing position is too low.
8. The exhausts are wrong (should be angled down and mostly covered by a fairing (you cant see the exhaust opening in side view photos)
9. Upper nose profile is off (not just the scoop but the upper profile from the turtle deck down to the spinner).

So why am I propagating another kit based on this same problematic three view? Well first this started out as a dimescale kit and so it has to be "simplified" and based on a published dimescale plan. The Isermann plan was published in the NFFS digest and I like the look of it. Second I don't have time to start a new MrSmoothie plan from scratch. Perhaps I will do it someday but not right now.

Attached files Thumbnail(s):
Mr Smoothie P-nut
Mr Smoothie P-nut
Mr Smoothie P-nut
Logged

F1B guy but its not my fault, Tony made me do it.
BG
Platinum Member
******

Kudos: 83
Offline Offline

Canada Canada

Posts: 1,644


Topic starter
Me with F1B - epic retrieval (flew 10km after DT)


WWW

Ignore
« Reply #1 on: September 30, 2018, 11:11:56 AM »

Ok So starting the kit.
The wood is good - I weigh and grade all of my wood and all wood that goes into each kit.  For my build I selected slightly stiffer C-grain wood because it has been a while since I built a peanut and I don't want to worry about delicate parts breaking under the pressure of my unpracticed digits. I don't think it is super important to use C-grain on these smaller models by the way. In some ways it is annoying to work with because it is a brittle and unforgiving at times. For the smaller kits I focus mainly on density and stiffness don't worry about the grain too much.
Disclaimer: The parts in this kit were taken directly from the Isermann drawing under the assumption that his build and subsequent corrections would result in a perfect fit.

I started with the nose block. It goes together well but I can tell that the height and width of the parts is slightly off. When shaped and sanded steps would still remain. So I added extra material (1 mm balsa) to the tops and bottoms of a couple of the formers. This will be fixed on kits I am shipping.
The nose plug is laminated as well and backed and fronted with 1/64th ply. the key slot is laser cut into the formers which makes aligning the formers and getting and accurate fit easy. The key tab is a bit of hard 1/16th.
A bit of careful sanding and fitting achieved a good fit of the nose plug into the nose block.

Next I built the stab and fin. All parts fit nicely and they came out with a reasonable weight (.5g). I also went ahead and added a carbon tube pivot incase I want to add a Dt option. Not everyone will bother with this but these folks will have to modify the structure to their taste.

The wing assembly went together ok, I will be modifying some of the ribs and the tip shapes to improve fit and alignment (it was not perfect on mine). Weight is ok, as I noted above my wood is heavier for this out door peanut so she is no featherweight.
Attached files Thumbnail(s):
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Logged

F1B guy but its not my fault, Tony made me do it.
Crabby
Titanium Member
*******

Kudos: 132
Offline Offline

United States United States

Posts: 2,145


I never met a modeler I didn't like



Ignore
« Reply #2 on: September 30, 2018, 11:42:21 AM »

looking good Bernard. Nice and light.
Logged

The Threadkiller!
BG
Platinum Member
******

Kudos: 83
Offline Offline

Canada Canada

Posts: 1,644


Topic starter
Me with F1B - epic retrieval (flew 10km after DT)


WWW

Ignore
« Reply #3 on: September 30, 2018, 11:58:44 AM »

Next: I laid up the fuselage sides, building as one normally would (pins with eraser or plastic pin clamps) on a cork building board.
After completing the fuselage sides I blocked them up using angled jigs (5.6 deg. past vertical; patterns supplied in kit going forward). I made my jigs by attaching paper sprayed with 3M spray to some deperon foam, and cutting them out. I forgot to take photos of the blocked up fuselage structure.

Once the basic framework was completed I added the top and bottom formers and the stringers.
The only unusual aspect is the cockpit frame. I decided to make this using balsa and 1/64th ply. This will allow me to wrap cellophane plastic around the frame to form the cockpit canopy.

When the fuselage was completed I assembled the bones to take a couple of pics. Included you see the paper air scoop and spinner. These come in the kit and require some paper modelling skills to get right.
Attached files Thumbnail(s):
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Logged

F1B guy but its not my fault, Tony made me do it.
bgrove
Gold Member
*****

Kudos: 18
Offline Offline

United States United States

Posts: 506




Ignore
« Reply #4 on: October 01, 2018, 12:27:47 PM »

Very nice work and low weight.  I'm going to have to try a laser cut kit someday - the perfect formers always amaze me  Smiley  I'll keep an eye on your build.
Logged
BG
Platinum Member
******

Kudos: 83
Offline Offline

Canada Canada

Posts: 1,644


Topic starter
Me with F1B - epic retrieval (flew 10km after DT)


WWW

Ignore
« Reply #5 on: October 03, 2018, 03:15:40 PM »

Next the tissue: The tissue is printed on a Epson workforce printer capable of printing 13x19" sheets. The pigment is waterproof and thinner proof but expensive (I get about 8 tissue sets per cartridge). For this model I am preshrinking the tissue to try to avoid the dreaded pretzel. My approach (borrowed from Michael Morrow's NOCAL approach) is to shrink the tissue on a screen (my bedroom window screen in this case. I have experimented with a failed tissue print (ran out of ink mid print) to see just how much shrink happens. Turns out after shrinking the tissue it shrinks about 3% across the grain (a 170 mm line is 165 mm after shrinking) and ~1% along the grain (100 mm is no 99 mm). After a couple of days the tissue expanded back to 167x100). I am going to shrink it again today to see what happens.

The next day I ran this test and basically got the same shrink as I got the first time.

So, given the minimal shrinkage observed in my preshrink experiment, I decided to forge ahead without any additional shrinking. For this model I am using coloured chalk to deepen the color and get a little opacity. I experimented with orange, white and yellow chalk and in the end decided on a mixture of white and yellow. The orange made the gold lettering go reddish whereas the white/yellow gave the red tissue more of an orange tinge (which is closer to the Mr Smoothie orange-red) and made the gold pop a little.

I covered the wing, stab and fin using glue stick. One downside of chalk is that it is harder to get the tissue to stick because of the chalk dust. I find I have to wet the tissue seams (I use a special and very convenient fluid for this - saliva).

After covering everything I put it back on the scale and got 5.9g including uncovered fuselage. So I am thinking around 10-11g AUW before rubber. Fuselage next.
Attached files Thumbnail(s):
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Logged

F1B guy but its not my fault, Tony made me do it.
BG
Platinum Member
******

Kudos: 83
Offline Offline

Canada Canada

Posts: 1,644


Topic starter
Me with F1B - epic retrieval (flew 10km after DT)


WWW

Ignore
« Reply #6 on: October 03, 2018, 03:25:12 PM »

So, finished the covering. She is 7.8g as is (including prop shaft) so with prop and a bit of detailing I expect to come in at around 10g.

Last steps will be to finish cockpit, attach air scoop permanently, spray with artists fixative to seal tissue, install cockpit canopy glazing,  and make and install prop.

BG
Attached files Thumbnail(s):
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Re: Mr Smoothie P-nut
Logged

F1B guy but its not my fault, Tony made me do it.
Pages: [1]   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!