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CEF speed contest Design Discussions (2014) - Page 4 Empty

CEF speed contest Design Discussions (2014)

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CEF speed contest Design Discussions (2014) - Page 4 Empty Re: CEF speed contest Design Discussions (2014)

Post  Mike Mulligan Tue Aug 12, 2014 2:39 pm

@JPvelo wrote:
Good question Mike and good point Phil.
I hadn't really thought about it until now. I lifted the rules for this from 1/2a profile proto and we've adapted them along the way to incorporate scale and try to get more speed from a reed powered plane.
The 12.5 biplane span is from the proto rules. That's a combined span of 25 inches. To me it would make sense to change the biplane rule to minimum combined wingspan of 25" with minimum 45 square inch wing area. That way you can make top and bottom span whatever you like as long as they hit the 25" combined span mark.

Thoughts?

Jim

I think I agree with Phil. I believe the 45 squares rule, and the requirement to look 'scale', would do a pretty good job of keeping everything fairly even. There were a few planes that were called "sesquiplanes" (As in one and a half wings) that could be accurately modelled with really small lower wing, but the spider's web of struts on those things would be penalty enough!

By the way, after doing some scribbling it does look like the 24" combined span could make it a bit tough to maintain a scale look without going way over 45 squares, for whatever that may be worth. Things start to look like two-winged sailplanes...

Discaimer: The plane I had in mind to build (Beck-Mahoney Scorceress) flew with both equal span wings and with a shorter lower wing. Either way you decide, it won't really affect what I had in mind, though with the shorter lower span I can get down to about 48 squares without it starting to look too funny! (Kinda looks funny enough already)

CEF speed contest Design Discussions (2014) - Page 4 Scorce10
CEF speed contest Design Discussions (2014) - Page 4 Beck-m10

Might only get one flight out of it; what are the chances of a successful landing on those bottom wings!

Cheers guys!

Mike
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Post  Mike Mulligan Tue Aug 12, 2014 3:06 pm

@JPvelo wrote:Details of my high tech intake system:
CEF speed contest Design Discussions (2014) - Page 4 7ZwBB5y
Firewall has two holes, an intake for the engine and an intake for the "airbox" that directs air to the engine.
CEF speed contest Design Discussions (2014) - Page 4 N3sZPuY
CEF speed contest Design Discussions (2014) - Page 4 D7auVz3
Detail of the airbox cut into the cheek block.
CEF speed contest Design Discussions (2014) - Page 4 B0BC6Ju
The intake tube.
CEF speed contest Design Discussions (2014) - Page 4 LL0oAtx
CEF speed contest Design Discussions (2014) - Page 4 JKeOnBs
What it looks like all put together.

Jim

Really nice! Simple and elegant. Can I ask about your fuel storage plans?
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Post  JPvelo Tue Aug 12, 2014 3:13 pm

Mike, cool plane!
I think it's best to just leave it at 12.5 minimum top and bottom and if you want to extend the top for scale look you can. Remember the model has to be recognizable as the subject, not an exact scale replica. That doesn't  mean you can make a two wing sailplane and try to pass it of as a stearman. lol! 

Jim
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Post  RknRusty Tue Aug 12, 2014 3:26 pm

Man I see more cool stuff in this thread.
This thing looks like two planes that got stuck...... well, just stuck!
 lol! 
CEF speed contest Design Discussions (2014) - Page 4 Scorce10

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Post  Mike Mulligan Tue Aug 12, 2014 3:49 pm

@JPvelo wrote:Mike, cool plane!
I think it's best to just leave it at 12.5 minimum top and bottom and if you want to extend the top for scale look you can. Remember the model has to be recognizable as the subject, not an exact scale replica. That doesn't  mean you can make a two wing sailplane and try to pass it of as a stearman. lol! 

Jim

Hahaha! Don't put ideas in my head!

 Hand Shake  12.5" for both sounds good.
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Post  getback Tue Aug 12, 2014 4:02 pm

Jim that system does look good, plenty of air flow and exhaust relief , but I am still with Roddie I think even if you had a pipe going directly into the vent ... unless you can figure how rich to set the engine before take off and not being able to adjust it in flight I cant see the factor , other than floating the reed . just my  Two Cents ( but it does look damn cool ) Getback ..... Thumbs Up 
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Post  JPvelo Tue Aug 12, 2014 4:05 pm

Mike,
I plan on using an external bladder secured through the spring end of a safety pin.
CEF speed contest Design Discussions (2014) - Page 4 3YI2w3e
CEF speed contest Design Discussions (2014) - Page 4 TDVQId1
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Post  Mike Mulligan Tue Aug 12, 2014 6:30 pm

@JPvelo wrote: That doesn't  mean you can make a two wing sailplane and try to pass it of as a stearman. lol! 

Jim

Look what I found!  That's as close to a two wing sailplane as I have ever seen!lol! 
CEF speed contest Design Discussions (2014) - Page 4 Biplan10
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Post  Mike Mulligan Tue Aug 12, 2014 6:43 pm

@JPvelo wrote:Mike,
I plan on using an external bladder secured through the spring end of a safety pin.

Nice. Simple and reliable is probably the best way to go, when you get right down to it.

Mike
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Post  Mike Mulligan Tue Aug 12, 2014 7:05 pm

Oh, and speaking of simple and reliable (not), here are some pics of the Red Baron progress.CEF speed contest Design Discussions (2014) - Page 4 101_0232
CEF speed contest Design Discussions (2014) - Page 4 101_0233

Since intakes seem to be en vogue right now, here is the ducting for this bird.
CEF speed contest Design Discussions (2014) - Page 4 101_0234

The part above the engine is the floor of the intake duct. The top will follow the fuselage line to just behind the spinner. I just couldn't resist using the scale inlet!
CEF speed contest Design Discussions (2014) - Page 4 101_0235
CEF speed contest Design Discussions (2014) - Page 4 Redbar11
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Post  batjac Tue Aug 12, 2014 11:25 pm

@Mike Mulligan wrote:

Look what I found!  That's as close to a two wing sailplane as I have ever seen!lol! 
CEF speed contest Design Discussions (2014) - Page 4 Biplan10

I've scammed rides in anything I could, figuring I'd fly anything once.  But I don't know as I'd try that one...

The "Not As Brave As He Thought" Mark
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Post  Theo Kleynhans Wed Aug 13, 2014 7:19 am

Thanks for the info guys regarding the electric props. So I will not be using one.

Mike, that Red Baron is looking great. As with your other model, beautiful work!!

Theo
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Post  Theo Kleynhans Wed Aug 13, 2014 7:28 am

I finished my Nemesis wing last night. This was my first try to do an airfoil.

CEF speed contest Design Discussions (2014) - Page 4 Img-2060
CEF speed contest Design Discussions (2014) - Page 4 Img-2062
CEF speed contest Design Discussions (2014) - Page 4 Img-2063

Now I need to start on the fuse and stab.

Theo
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Post  OVERLORD Wed Aug 13, 2014 8:46 am

Very nice Theo!!
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Post  pkrankow Wed Aug 13, 2014 11:46 am

@Theo Kleynhans wrote:I finished my Nemesis wing last night. This was my first try to do an airfoil.

CEF speed contest Design Discussions (2014) - Page 4 Img-2060
CEF speed contest Design Discussions (2014) - Page 4 Img-2062
CEF speed contest Design Discussions (2014) - Page 4 Img-2063

Now I need to start on the fuse and stab.

Theo

Top notch awesome!
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Post  Mike Mulligan Wed Aug 13, 2014 12:47 pm

Absolutely stunning!
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Post  Cribbs74 Wed Aug 13, 2014 2:31 pm

Looks way better than my first try! And second...and third... Very Happy 
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Post  Theo Kleynhans Thu Aug 14, 2014 12:05 am

Thank you for the kind words Guys.

I am trying to really make this a nice plane.

Theo
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Post  getback Thu Aug 14, 2014 7:11 am

Really looking sharp there Theo !!  Cool
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Post  Theo Kleynhans Fri Aug 15, 2014 6:21 am

Hi Guys

I sanded the Stab last night of my Nemesis. It came out quite nice, but I am a bit worried, it is extremely soft and flexable. I used 3mm balsa. But I am hoping it will stiffen with the sanding sealer and paint.
CEF speed contest Design Discussions (2014) - Page 4 Img-2064
CEF speed contest Design Discussions (2014) - Page 4 Img-2065

Here are the wing and stab together:
CEF speed contest Design Discussions (2014) - Page 4 Img-2066

Theo
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Post  pkrankow Fri Aug 15, 2014 7:07 am

Depending on the type of sealer and paint, yes it will stiffen. If you are using dope (fuel proof), or lacquers(generally not fuel proof) for the base coats it will soak in, harden and stabilize the wood. If you are using enamels it will not.

I do not know how well the polyurethane options work (both oil and water based) as I have not worked with balsa and polyurethane much. I know that using cornstarch with dopes and polyurethanes make a good sandable filler paint that will fill the grain fast for that perfect finish.

Phil
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Post  Theo Kleynhans Mon Aug 18, 2014 3:52 am

Thanks for the info Phil. I will not be using enamels, so the lacquers should stiffen the stab.

I finished the fuselage over the weekend. The plane is now starting to come together.

Here was the fuse with the slots cut for the wing. I fitted them to see what she looked like.
CEF speed contest Design Discussions (2014) - Page 4 Img-2067
CEF speed contest Design Discussions (2014) - Page 4 Img-2068

Then I finished with sanding the Fuse:
CEF speed contest Design Discussions (2014) - Page 4 Img-2070
CEF speed contest Design Discussions (2014) - Page 4 Img-2071

Now I guess I need to take some time and figure out how I will do the bellcrack and what I am going to do at the nose. I have not decided how I will mount the engine and what type of cowling I will do. This is now the difficult part for me.

Theo
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Post  roddie Mon Aug 18, 2014 6:03 am

SLICK Theo!!!!! The airfoil-sanding job on your stab looks awesome! The whole model looks AWESOME!! One of my favorite stages of building a profile model, is the instant transformation that takes place.. when you slide the wing and stab into the fuse, after the fin/canopy is attached.  Flying
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Post  JPvelo Mon Aug 18, 2014 7:25 pm

That is a thing of beauty Theo!

Jim
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Post  RknRusty Mon Aug 18, 2014 10:39 pm

Theo
I sanded a similar foil on the inboard side of the fin on my Baby Flite Streak. The outboard of the fin was left flat.That was intended to cause the air flowing over the curve to form a vacuum and theoretically pull the tail into the circle resulting in a slightly helpful outward yaw.

Yours is nicely shaped but i can only see the curved outboard side of the fin. Unless there is an equal foil on the inboard side, this rudder is going to yaw the tail out and the nose into the circle. Am I missing something? It wouldn't be the first time.
Rusty

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