Cox Engines Forum
You are not logged in! Please login or register! Guests are limited to posting in the "General Questions (Guest Posting Allowed)" section only. Becoming a member is fast, easy and FREE!


speed - CEF speed contest Design Discussions Babe_b10
Log in

I forgot my password

Search
 
 

Display results as :
 


Rechercher Advanced Search

Cox Engine of The Month
June-2019
robot797's

"cox 049 gasoline"

More info on this engine!



PAST WINNERS
Speed Contest 2019
CEF Traveling Engine

Win This Engine!
The Traveling Prop
Gallery


speed - CEF speed contest Design Discussions Empty
World of Aviation

CEF speed contest Design Discussions

Page 1 of 40 1, 2, 3 ... 20 ... 40  Next

Go down

Mad CEF speed contest Design Discussions

Post  pkrankow on Tue Nov 12, 2013 4:51 pm

What the title says.  A place to talk smack and share pictures and design.

BTW I'm building an Air Tractor, probably the 504.

http://www.airtractor.com/aircraft/504

My daughter will be delighted.

Phil

speed - CEF speed contest Design Discussions Dusty


Last edited by pkrankow on Fri Nov 22, 2013 11:58 am; edited 1 time in total
pkrankow
pkrankow
Diamond Member
Diamond Member

Posts : 2984
Join date : 2012-10-02
Location : Ohio

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  pkrankow on Tue Nov 12, 2013 5:50 pm

MY wing is a dead straight stick, 15 inches long, 3 inches wide. I decided to use a K-F airfoil to reduce drag, and provide an "wind shadow" for the control lines. I am using 1/8 inch and 1/16 inch materials for the wing. To hopefully limit warping I am making the wing lite-ply by using the 1/16 in the direction of travel instead on in the span.

Phil
pkrankow
pkrankow
Diamond Member
Diamond Member

Posts : 2984
Join date : 2012-10-02
Location : Ohio

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  Kim on Tue Nov 12, 2013 6:19 pm

SMACK TALK !!!!!!!!!!!

speed - CEF speed contest Design Discussions Sleep_10
Kim
Kim
Top Poster
Top Poster

I Support My Forum

Posts : 6561
Join date : 2011-09-06
Location : South East Missouri

View user profile

Back to top Go down

Mad Roddie's "Rare-Bear" F8F-2

Post  roddie on Tue Nov 12, 2013 6:53 pm

I've built smaller planes... but I can't remember when...

speed - CEF speed contest Design Discussions 11-11-10
speed - CEF speed contest Design Discussions 11-11-11
speed - CEF speed contest Design Discussions 11-11-12
roddie
roddie
Top Poster
Top Poster

Posts : 6506
Join date : 2013-07-17
Age : 59
Location : N. Smithfield, Rhode Island

View user profile http://www.stilburnin.com

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  pkrankow on Tue Nov 12, 2013 8:17 pm

Your ruler is marking out a point on the rules I find fuzzy.  Where is length measured from?  In a cowled fuselage I would presume the front of the cowl, so the engine counts, but not the propeller and related parts.

Based on this premise you have 1 1/2 inches MORE fuselage than necessary.

I am undecided between a cowl, or doing an offset mounting for cosmetics, or some type of combination.

I plan on a weight box for nose weight since I tend to build tail heavy.

Phil
pkrankow
pkrankow
Diamond Member
Diamond Member

Posts : 2984
Join date : 2012-10-02
Location : Ohio

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Tue Nov 12, 2013 10:02 pm

pkrankow wrote:Your ruler is marking out a point on the rules I find fuzzy.  Where is length measured from?  In a cowled fuselage I would presume the front of the cowl, so the engine counts, but not the propeller and related parts.

Based on this premise you have 1 1/2 inches MORE fuselage than necessary.

I am undecided between a cowl, or doing an offset mounting for cosmetics, or some type of combination.

I plan on a weight box for nose weight since I tend to build tail heavy.

Phil
Length is measured from the face of the prop drive plate wether cowled or not.

Jim
JPvelo
JPvelo
Diamond Member
Diamond Member

Posts : 1962
Join date : 2011-12-02
Age : 51
Location : Phoenix

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  roddie on Wed Nov 13, 2013 5:52 am

pkrankow wrote:Your ruler is marking out a point on the rules I find fuzzy.  Where is length measured from?  In a cowled fuselage I would presume the front of the cowl, so the engine counts, but not the propeller and related parts.

Based on this premise you have 1 1/2 inches MORE fuselage than necessary.

I am undecided between a cowl, or doing an offset mounting for cosmetics, or some type of combination.

I plan on a weight box for nose weight since I tend to build tail heavy.

Phil
I'm glad you raised a point Phil, because I went back and re-read the rules... to find that my "wing" is an inch "short" in span... (for some reason I thought the rules stated a 14" minimum, and I started building right away) ... Luckily; I didn't cut the radius of the tips in yet... because I'll need to add a 1/2" tip per side... or maybe "more" now that I'm thinking about it.

The "fuse" I was more conservative with... and went with the 12" minimum; less the cowl... so the o/a length will be approx. 15".

I felt that if I make the F8F too small; I will have trouble with "scale-like" proportions... and also be too "light" a weight for 42 ft. line-length. I am surprised that there aren't any restrictions on line "type".

I don't understand the dis-allowing of a "stooge" though...
roddie
roddie
Top Poster
Top Poster

Posts : 6506
Join date : 2013-07-17
Age : 59
Location : N. Smithfield, Rhode Island

View user profile http://www.stilburnin.com

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  roddie on Wed Nov 13, 2013 6:05 am

pkrankow wrote:

I plan on a weight box for nose weight since I tend to build tail heavy.

Phil
You might want to consider using a carbon-fiber (lightweight) pushrod. You will save a lot of weight rearward the c/g that way...

Rog
roddie
roddie
Top Poster
Top Poster

Posts : 6506
Join date : 2013-07-17
Age : 59
Location : N. Smithfield, Rhode Island

View user profile http://www.stilburnin.com

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  pkrankow on Wed Nov 13, 2013 6:13 am

roddie wrote:
I don't understand the dis-allowing of a "stooge" though...
Um...now I can't even participate if use of a stooge is prohibited. I doubt I can get a second person to assist me.

Phil
pkrankow
pkrankow
Diamond Member
Diamond Member

Posts : 2984
Join date : 2012-10-02
Location : Ohio

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  Kim on Wed Nov 13, 2013 6:29 am

I was thinking that this applied to the "Air-Launch" Stooge like Rusty and I use...

The pin and string type is probably allowed...

speed - CEF speed contest Design Discussions 3_23

speed - CEF speed contest Design Discussions Img_2610








Last edited by Kim on Wed Nov 13, 2013 7:01 am; edited 1 time in total
Kim
Kim
Top Poster
Top Poster

I Support My Forum

Posts : 6561
Join date : 2011-09-06
Location : South East Missouri

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  Kim on Wed Nov 13, 2013 7:00 am

roddie wrote:I've built smaller planes... but I can't remember when...

speed - CEF speed contest Design Discussions 11-11-10
speed - CEF speed contest Design Discussions 11-11-11
speed - CEF speed contest Design Discussions 11-11-12
Last Photo looks like a Rutan Vari-Viggen !!!
Kim
Kim
Top Poster
Top Poster

I Support My Forum

Posts : 6561
Join date : 2011-09-06
Location : South East Missouri

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Wed Nov 13, 2013 7:04 am

pkrankow wrote:
roddie wrote:
I don't understand the dis-allowing of a "stooge" though...
Um...now I can't even participate if use of a stooge is prohibited.  I doubt I can get a second person to assist me.

Phil
I was referring to wing type stooges when I said stooges cannot be used. The reason being is I don't know if you can successfully stooge or hand launch a model this small, especially if you go with a small speed type elevator.  You are welcome use a "pin and string" type stooge. We can also be flexible on the stooge/hand launch if you don't have a paved surface to fly from. I certainly don't want want this rule to prevent anyone from competing.  Phil, from what I gather in your post you have a great deal of experience in the hobby and I look forward to you competing.

Jim
JPvelo
JPvelo
Diamond Member
Diamond Member

Posts : 1962
Join date : 2011-12-02
Age : 51
Location : Phoenix

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  pkrankow on Wed Nov 13, 2013 7:54 am

I'm well read...sorta... when I was young we did this as a family, although speed and self designed planes were not done much.

Airfoil and main wing, still needs trim and sanded, and line guide (only one for both lines)

speed - CEF speed contest Design Discussions Img_2011
I plan to test fly from a wing stooge, but do my run with a pin type stooge in a parking lot.

Phil
pkrankow
pkrankow
Diamond Member
Diamond Member

Posts : 2984
Join date : 2012-10-02
Location : Ohio

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Wed Nov 13, 2013 8:29 am

pkrankow wrote:I'm well read...sorta...  when I was young we did this as a family, although speed and self designed planes were not done much.

Airfoil and main wing, still needs trim and sanded, and line guide (only one for both lines)

speed - CEF speed contest Design Discussions Img_2011
I plan to test fly from a wing stooge, but do my run with a pin type stooge in a parking lot.

Phil
That duster is an excellent choice, wish I would have thought of it.  When I was employed as an a&p mechanic I maintained turbo thrushes that were converted to fire retardent bombers.

Jim
JPvelo
JPvelo
Diamond Member
Diamond Member

Posts : 1962
Join date : 2011-12-02
Age : 51
Location : Phoenix

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  duke.johnson on Wed Nov 13, 2013 9:26 am

Thanks Phil for starting this thread. Like Kim, I will start blabbing soon, I'm sure. I would have started already, but I haven't figured you what I'm doing yet. When we first started talking about the contest I wanted to build a mouse 1 plane, but I don't think it would meet the scale design idea.

That being said, I've never built a scale plane before. Could someone tell me what scale means? I figured it means it will look some what like a real plane from the profile. And I think I understand it can have any paint scheme.

Sorry for being a dumb plumber, or is that a plumb dumber.

Can't wait to get started!
duke.johnson
duke.johnson
Diamond Member
Diamond Member

Posts : 1734
Join date : 2012-11-05
Age : 47
Location : Rochester, Washington

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Wed Nov 13, 2013 10:35 am

duke.johnson wrote:Thanks Phil for starting this thread.  Like Kim, I will start blabbing soon, I'm sure.  I would have started already, but I haven't figured you what I'm doing yet.  When we first started talking about the contest I wanted to build a mouse 1 plane, but I don't think it would meet the scale design idea.

That being said, I've never built a scale plane before.  Could someone tell me what scale means?  I figured it means it will look some what like a real plane from the profile. And I think I understand it can have any paint scheme.

Sorry for being a dumb plumber, or is that a plumb dumber.

Can't wait to get started!
What I envision for this is models that follow the scale outline of the fuselage AND the wing/elevator as closely as possible while tweaking dimensions to fit within the contest rules. For example, if you build a spitfire it needs an elliptical wing not a straight 15 inch plank with a constant 3 inch chord. Feel free to enlarge horizontal stabilizers within reason to make a more stable flying model.

Jim
JPvelo
JPvelo
Diamond Member
Diamond Member

Posts : 1962
Join date : 2011-12-02
Age : 51
Location : Phoenix

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  duke.johnson on Wed Nov 13, 2013 12:08 pm

Great. And it doesn't have to be a military plane? It can be a scale version of a race plane?
duke.johnson
duke.johnson
Diamond Member
Diamond Member

Posts : 1734
Join date : 2012-11-05
Age : 47
Location : Rochester, Washington

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  pkrankow on Wed Nov 13, 2013 12:13 pm

I'm building a crop duster.

If you follow the link in my first post you find line drawings of the airplane.  To get the profile I am using the Air Tractor 502 (The wing is the same on several versions.)  I took the image, grabbed it to my clip board, put it into an image editing program (GIMP, it's free) and I resized the image until the fuselage was the correct size (there is a measuring tool in most image editors) I then cropped the image to fit on two pieces of paper at full size and printed it out.  If I had legal paper it would have fit on 1 page.

I then cut the paper out, and trace the drawing onto my wood.  I will cut the rudder out separately since it is getting made from thinner material.

If the wing scales properly to the desired square inches then you can do the same with the wing.  If not you have choices of enlarging it and changing the sweep angle after tracing the wing tip, or measuring and drawing.  I chose to measure and draw since my wing is a straight stick.  I will do the same with the rear wing.

Line drawings are available for most aircraft that were ever produced.

Now, before cutting out the parts you might want to verify that the wing chord is similar to the plan, or alter the profile (and/or wing) to suit.  

These planes are going to run fast, and need to be slightly nose heavy.  They should fly with the balance point on the LE of the wing.  The should fly better with the balance point over the wing, forward of 25% wing chord.  I plan to balance at 10%-15% wing chord or 1/4 to 1/2 inch back from the LE for the test flight.

Phil
pkrankow
pkrankow
Diamond Member
Diamond Member

Posts : 2984
Join date : 2012-10-02
Location : Ohio

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Wed Nov 13, 2013 12:25 pm

pkrankow wrote:

These planes are going to run fast, and need to be slightly nose heavy.  They should fly with the balance point on the LE of the wing.  The should fly better with the balance point over the wing, forward of 25% wing chord.  I plan to balance at 10%-15% wing chord or 1/4 to 1/2 inch back from the LE for the test flight.

Phil
I would recommend kicking the landing gear pretty far forward as these things will be nose heavy lawn darts once the engine quits.

Jim
JPvelo
JPvelo
Diamond Member
Diamond Member

Posts : 1962
Join date : 2011-12-02
Age : 51
Location : Phoenix

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  duke.johnson on Wed Nov 13, 2013 12:35 pm

Phil
where did you find the drawings you are talking about?
duke.johnson
duke.johnson
Diamond Member
Diamond Member

Posts : 1734
Join date : 2012-11-05
Age : 47
Location : Rochester, Washington

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  JPvelo on Wed Nov 13, 2013 12:55 pm

duke.johnson wrote:Phil
where did you find the drawings you are talking about?
Do a google image search for "" name of aircraft" 3 view".  Example: "P51 3 view". You should find what you need.

Jim
JPvelo
JPvelo
Diamond Member
Diamond Member

Posts : 1962
Join date : 2011-12-02
Age : 51
Location : Phoenix

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  pkrankow on Wed Nov 13, 2013 2:30 pm

I just showed MY homework...

Here I go for today. Lots to do still, tail wheel, con trolls, motor mount... I might change the nose, but I might keep it this way.

Phil
speed - CEF speed contest Design Discussions Img_2012
pkrankow
pkrankow
Diamond Member
Diamond Member

Posts : 2984
Join date : 2012-10-02
Location : Ohio

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  duke.johnson on Wed Nov 13, 2013 2:48 pm

Looks really nice Phil. I was thinking of cutting my fuse that way, no cowl. I like it.

I've been blowing up drawings and trying to decide what model. I'm thinking a military plane in a racing paint scheme.
duke.johnson
duke.johnson
Diamond Member
Diamond Member

Posts : 1734
Join date : 2012-11-05
Age : 47
Location : Rochester, Washington

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  roddie on Wed Nov 13, 2013 9:06 pm

duke.johnson wrote:Looks really nice Phil. I was thinking of cutting my fuse that way, no cowl. I like it.

I've been blowing up drawings and trying to decide what model.  I'm thinking a military plane in a racing paint scheme.
Hey Duke... How about a Hawker Sea Fury? Plenty of racing heritage there!

speed - CEF speed contest Design Discussions Hawker10
roddie
roddie
Top Poster
Top Poster

Posts : 6506
Join date : 2013-07-17
Age : 59
Location : N. Smithfield, Rhode Island

View user profile http://www.stilburnin.com

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  RknRusty on Wed Nov 13, 2013 9:16 pm

I better get out the graph paper and commence to drawing, lest I get dusted!

_________________
Don't Panic!
...and never Ever think about how good you are at something...
while you're doing it!


My Hot Rock & Blues Playlist
RknRusty
RknRusty
Moderator

Posts : 10762
Join date : 2011-08-10
Age : 63
Location : South Carolina, USA

View user profile

Back to top Go down

Mad Re: CEF speed contest Design Discussions

Post  Sponsored content


Sponsored content


Back to top Go down

Page 1 of 40 1, 2, 3 ... 20 ... 40  Next

Back to top

- Similar topics

 
Permissions in this forum:
You cannot reply to topics in this forum