dieFluggeister

Looking to finish up the drafting on this one and hoping you could lend me your critical eye. Please let me know your thoughts.

It uses the Surestart but is more designed for the Killer Bee. Its designed to keep frontal area to a minimum and the cramming of the servos show it. Elevator uses a flexi-cable, and tank is scratch. Wings are balsa sheeted with 1/32 but could be covered framework to reduce weight. I estimate 11-12 oz. I have yet to show a cowl for the engine and dihedral braces.

The wing is uses a MH44 racing airfoil that, while it ads weight, should reduce drag and increase lift.

matchlessaero

Looks good DF! I would change only one thing... Make it a highwing. Less drag, easier to land, easier to launch....

dieFluggeister

I made it a low wing simply to balance drag forces on each side of the thrust line. But since the fuse is symmetrical, it could easily built in a high position.

ptulmer

My Feedback: (5)

Don't get me wrong, I LOVE it. But, you might be overthinking the wing. If you truly want to just go fast, why not try a sheet wing? Lighter, easier to build, less drag, etc.

combatpigg

My Feedback: (3)

Good points. It would make for a handsome looking plane with good performance, but would have a hard time keeping pace with a SWR. It's kind of amazing that a sheet of solid, light balsa can out perform mans' attempts to do better with exotic materials and methods. The SWR will allow the engine that it is bolted to, to unload more than any "built up" model that I've ever tried with 1/2A power.

dieFluggeister

LOL, I knew I would catch hell for a built up wing!

Well, I really wanted this airfoil and considering my sanding skills, I would fail miserably if I tried to get it from a solid piece.

Point is well taken though, I hate building almost as much as sanding.

DICKEYBIRD

Depends on what the task is. If'n it's "Let's go as fast as we can in a straight line with a SureStart" then the SWR prolly (maybe?) wins. If it's "Let's race, mano-a-mano for 10 laps around the pylons with a SureStart" I think the built-up (or preferably 1/32 balsa sheeted 1 lb./cu. ft. foam) wing with a high AR and a proper (optimized for the task) airfoil wins handily. This is due to the huge difference in induced drag during the 3 high G turns per lap.

Pylon racing is just 2 drag races between 3 gut wrenchin', speed suckin' corners. The speed and momentum loss suffered by the SWR in the turns can't be made up for by its higher top speed, IMO. You don't really notice the speed loss in the turns too much watching a a pylon race but it's there, trust me.

Now if the task involves one of C/P's Foras or Cyclons on the nose, forget it. Them things don't follow the universal laws of physics and aerodynamics![X(]

ps: Cool lookin' racer there D/F!

ptulmer

My Feedback: (5)

DB, I'll put up an 8-9oz SWR against ANY 11-12oz built-up wing in the turns! My little "Killer Buzz" can make a turn without any visible loss of speed. I'm sure there's some loss, but nothing like my 12oz DNU!.

dF, I ain't trying to give you hell! I'm just trying to learn from someone who actually does the math.... (hint,hint, do the weight math. How much more will yours weigh?)

dieFluggeister

Keep in mind this design is just math and paper. Real World tests against the Killer Buzz and Annhilator will be another story!
[>:]

I did a comparison of airfoils below and found a big difference in the amount of drag vs. lift. To me it looked like the MH44 had a very wide range of lift (AOA) with very little change in drag. The coefficient of lift for small planes like these is in the 0.07 range, right in the sweet spot for this airfoil.

The math says it'll do a 30' radius turn at 100mph at 23 G's with less than an ounce of additional induced drag! In which case it should really 'groove' around the corners. (Unless I'm wrong, in which case please refer to "Sometimes I just make stuff up")

ptulmer

My Feedback: (5)

Reshape the front of the simplex6 airfoil to look like the mh44 and make the total thickness 3/16. Now remove 33% of the weight from the airplane. (12oz down to 8oz)

Don't get me wrong, I'm not trying to discourage you. It should fly very well. And I will enjoy watching you build and fly this. Didn't want you to be disappointed when I punish everyone who dares race me... It's spankin' season and I got a hankerin' for some spankerin'!

dieFluggeister

LOL, No - discouragement is having it spiral out of the air around turn #1! I appreciate your thoughts.

BTW, how do you manage 8 oz when my equipment weighs more than that!? What battery are you usin'?

ptulmer

My Feedback: (5)

The KB has two hs-55's, a feather receiver, and a 110mah battery. It weighs 9oz at the moment, but I'm redoing it with lighter covering. (monokote on right now) Also changing to a lighter(!) nimh battery. I do think that your's will be lighter than 12oz.

DICKEYBIRD

BEEP! Wrong! ALL aircraft respond to the same rules....be dey solid balsa or built up wings. Increase the the lift (like in a tight turn) and the drag goes up, speed goes down. It's just one of them law things. The better you control induced drag, the less speed you lose while making the turn and the more speed you have entering the straight.

On a short course with little airplanes, it all comes down to piloting skills and adrenaline control
anyhoo. Amazing how a "low key" race will get your heart a'hammerin' and your thumbs a'shakin!

Man, I wish you guys were closer.[>:]

ptulmer

My Feedback: (5)

What better way to control all that than to drop the weight by 1/3? Yep, my eyes ain't so good, but if you can measure the difference by sight, there's five bucks in it.

dieFluggeister

I've been using Monokote hinges on most of my small stuff. Have you guys had any trouble with them detaching, especially at greater speed? What is your preference?

Schu

My Feedback: (5)

PT,
Are you planning on using the Killer Bee on your SWR at the fly-in? I have a engine also, but per your opinion I went w/ the Black Widow, because of the required 6 x 3 prop. If you think I can crank up the stock Killer Bee w/ the 6 x 3 prop I will switch engines. Maybe I need to try it.
By the way I have a SWR that I need to post pictures of that I think will give you some competition. It is quick, but not like my Shrike w/ the Norvel- I wish we could use the .061 w/ the SWR - I think that it would be faster. Dale

ptulmer

My Feedback: (5)

The race requires a black widow/sure start engine. The killer buzz may or may not be my designated racer. I've got a 100mph killer bee that needs a good slick home. (no, it's not stock!) Whichever racer I enter will have a sure-start. Put a 4.2x4 on the killer bee and stand back! It's a good match for a SWR, just not race legal.

dF, I use a standard CA hinge cut in half. Or should I say half-a CA hinge? Probably not the best method...

flyswatter

df:

I love your engineering approach "Sometimes I just make stuff up." I have used that method myself sometimes.

Seeing as how you have actually put pencil to paper and calculated the induced drag, well then, I guess I would have to agree with you. But most of the race is in straight lines between the turns. If pt could convince me that the induced drag and corresponding speed loss by the SWR in the turns is offset by its quicker acceleration on the straights (due to lower weight and overall frontal drag), well then, I think we won't know until we put them head to head! But for the NC race, I don't think it will come down to induced drag. DB is right about the adrenaline rush. I suspect, when it hits during a race, it will probably put most of us into the ground! It should be fun!

You bring up a good question about the Monokote hinges. I use to use those things all the time, but I have gotten away from them. I do not remember the Mk hinges ever causing a problem. Course back then, my planes lasted only a little less than they do now, so they never got a chance to age - although I have a Headmaster with Mk hinged ailerons and they are still on the wing after almost 35 yrs; however, I wouldn't want to fly them right now. Actually, I keep thinking about trying sealed hinge lines using Mk full length hinges - just haven't gotten to it.

scudrunner77

I use the CA hinges myself... I have a sheet of it and just cut pieces out that look about right.

DF- Good like plane... I'm sure it will go like heck!

All this talk about drag and which wing is better... It seems to me that it would be hard to tell unless a SWR and build up winged plane took the course with the same weight and power, and were flow by very consistent pilots. But it sounds like many of us here (including me) are not hardened experienced racers and so I think the winner will be the one who can keep it tidy around the course. As for me... I'm building a hybrid wing so I have an excuse either way!

ptulmer

My Feedback: (5)

Scuddy, you hit the proverbial nail here. Weight is the real issue here. Drag, blah, blah. The lower total weight has alot less to worry about here. Especially since we're talking (hypothetically) about a 33% loss of weight!!! Moving that through a turn requires much less effort. (before somebody gets mad, I've been doing shots with my sister... can't hardly see the screen!)
I REALLY doubt dF's airplane will weigh as much as he thinks. A friendly round around the pylons should help... dF, you can't imagine the respect I have for someone that sits down and does the kind of work you do. Flyswatter can, he's an AE. Although I give him a hard time every chance I get, he can tell you the sheer reverence I talk about most of you guys. Even Dickeybird... (yes, even you COMBATPIGG!) It is amazing to me how much my building style has been influenced by guys I will see soon and guys I will probably never meet in person!
Whoever came up with the idea of imbedding the torque rods in epoxy the other day, I could kiss your feet right now! Yet another magnificent idea!

(gotta go sober up...[&:])

I love you, MAN!

[sm=lol.gif]

combatpigg

My Feedback: (3)

To my way of thinking, smaller and lighter will win every time. I think the 8 oz racer is close to being as small and light as you can take it. It looks like a little Q500 out there. It flashes around the poles.

To prove the point,[as to which school of thought is better] it would take lots of time to get a couple of guys who are in good enough practice with well trimmed planes to see what the difference is. With the limited speed race coming up, it will be a total crap shoot between tortoises, hares and everything else in between. I predict the race will go to the guy who can fly the cleanest race. Hopefully there will be lots of time set aside for "GRUDGE [>:][>:][>:] RACING"! Look out though, there might be a few outlaw planes [with hopped up reedies] there that can really light it up!

rrragmanliam

My Feedback: (1)

Hello Ptulmer,

It was Clean from Parkville MO. that came up with that one. I agree, what a great idea. It's a pain in the arse bending aileron linkages with the tubing. Per his suggestion I tried one with some scrap and it had less slop than my "tubed efforts". I'll never do it the old way again.

Darren

ptulmer

My Feedback: (5)

Well, thankfully he's far enough away that foot-kissing ain't possible!

rrragmanliam

My Feedback: (1)

Yea lucky for him!

combatpigg

My Feedback: (3)

Besides a radar gun, another useful tool to measure airframe efficiency would be an audio tach, or FDR to measure inflight rpm. You can tell from the sound of the engine on the straights and in the turns as to what is going on up there. You can only make a fuselage so light and clean, so that is almost a constant. What makes a real difference is the planes' AUW and the wings' size and shape. Keep going down in size until you go slower. The compact wing designs will hold their original shape better in high G situations and the plane will negotiate the turns predictably. It doesn't take much wing flex to throw you off course if you are really moving.

Do those charts and graphs tell you guys how the wing behaves while the plane is flying the course between 60 and 90 degrees to the ground? On a 200 foot course, my SWR wants to stay in a hard left bank for the entire lap. On the straights, the wing is acting more like a vertical stab and more area would be a disruptive force, especially in the wind.

There are some good analogies and comparisons to our argument lurking in auto racing. You basically can't make a race car light enough , some one will always figure out a way to put the power to use, no matter how light you get. I think the real challenge here is to make a built up version of the carved wing that is lighter and has better aerodynamics, but until the 1/2A racing scene heats up around here, I'll leave that challenge to those of you who are in the heartland of what's happenin' with 1/2A !