CEF speed contest Design Discussions

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

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 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

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...

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

The pin and string type is probably allowed...

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

Last Photo looks like a Rutan Vari-Viggen !!!

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

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)


I plan to test fly from a wing stooge, but do my run with a pin type stooge in a parking lot.

Phil

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)


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

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 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

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

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 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

Phil
where did you find the drawings you are talking about?

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

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

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 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!

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