Ok, I have never done this before so don't laugh....I always wanted to make my own design and with Dave's help answering my questions about the CAD software I was able to draw up some plans. I wanted to make a very small & light plane based on the glh(and to be very fast). So far this is what I got....the wingspan is 14"...the fuse is a little under 12". What you see so far weighs in at .6oz. And yes I want to try a black widow on it. I know it will be a lot of engine for it, I think I can get the total weight around 6oz(I hope). I am concerned about the balance as well as the wing loading(the wing is only 42 sq in), if I calculated at 6oz AUW the wing loading would be 20.58oz.

I know the people on this forum have a lot of experience with designing and building and I wanted to see what you thought and if I am way off base with this idea.

thanks

-Bill

BSARG has left the world of model aircraft as we know it and entered the world of model rocketry

That plane scares me just thinking about it. My latest 010 plane has 8 more inches of span. There's no way my poor eyes and trembly fingers could control it with a BW but I'd love to watch someone else do it!

Thats gonna be a rocket alright...I have a glh 2 and the span is 32"...if it flys it should be fast...sack of potatos fast[8D]..Rog

I'd have to go and weigh my Littlest Stick to figure out just how much over the top you are with this. And it IS over the top. So the question is by how much.

You've made the nose much too long to balance with a Black Widow. The swept back wings means that it's even longer since the MAC of the wing is roughly at mid span and the CG will be around 1/3 back from the leading edge at that point. Combind that with a low weight for gear and model and you're going to need a LOT of tail weight for this one.

Basidally your wing should be mounted with the leading edge touching the back of the firewall I'd say. Or perhaps only a 1/2 inch behind it.

The fuselage could be half as wide and still everything will fit. The smallest I've gone is just over 100 square inches with a Fora .049, and it has a decent enough glide to allow choosing landing spots. Hopefully your project works out, but I don't think it can be built light enough to fly well with a .049 engine.

Nice looking frame!
That said, the stabilizer may be a tad small in area and could give a problem with directional stability.
The overall small size may tend to make the model touchy to control or some may use the term "twitchy". This can cause the average spectator to think that the plane is not under positive control.

One thing that concerns me is what the stall speed of the plane will be and how strong of a launch will be needed to get it up to a controlable airspeed. Do you know what the wing area is?

I do hope that you will have someone else launch it for you so that you will have both hands on your transmitter the moment it becomes airborn.
Since it will no doubt have a relatively high wing loading, going fast will not be an option, it will be a primary neccessity!

Another thought just hit me, when the engine quits (and it will unless you land it under power) I think the landing will be a very, or should I say a scary short time away. I imagine trying to line up a landing once engine dies will be quite challanging.

Something else in the back of my mind keeps reminding me that an official baseball must have a circumference between 22.9 and 23.5 cm and weigh between 5 and 5 1/4 ounces and how well it might fly with a pair of smallish wings. Just a perspective thing I suppose.

The wing looks plenty strong and I don't think you will hjave a problem of it folding up. Still i would put shear webbing between the spars for some insurance. What is the thickness of the center sheeting?
Overall appearance looks good but I will have to agree with Bruce about the CG issue. Gonna be hard to balance it where it needs to without adding unwanted ballast weight. I doubt you will want to add weight if you can avoid it!

I will be following along to see how it all turns out.

Robert

Its a design attempt!! give the guy a break, I'm guessin its for the 1/2A pylon races sceduled for May,,its purpose is to last for about 20 laps at full throttle and come out in first place..and it just may do that!!...My 2 racers have 24 and 28 inch wingspans one with a golden bee the other with a norvel .061...if you ever saw Deadstick swap out his .010 on a wee stick for an .049 and watch it fly..you'd know what the goal is!!!...FAST!!!!.....No it wont glide in great but who cares!!!...........Rog

I'm thinking a Killer Bee on one of these would be competitive

http://www.guillow.com/GuillowDetail...=12&FamilyId=2


Seriously, good luck with your project! It may just be more successful than it would appear at first blush.

It still looks like it'll come out too nose heavy.

Either way a daring endevour. Looking forward to hearing the outcome. And good luck with the racing to both Bsarge and you too Rog'.

Howdie gents. Looks like your haveing fun. Heres a thought, the wing tips are slanted back to the t.e . this will most likely cause a vacume and slow it down and make it prone to tip stalling. hkbii.

Hot Doggies Bill you are on fire! Sure go ahead and move the wing forward a little. Maybe add a little area on the back end but keep on truckin'! I think it looks good enough to eat (that's a cheap reference to one of your famous hot dogs). Heck half the fun of building your own design is not knowing how (if) it will fly. Just make sure you have friends with you when you go for that first launch. A true friend will either celebrate with you, or . . . well you know.

Rog, Bill and all others, I mean no disrepect by my comments. After reading through them it sure seems dry and rather non supportive. I would rather be supportive. At least Bill is trying to do his own thing and not asking where to buy an off the shelf RTF simply to bypass the construction issues.
Creativity is a great thing and this plane certainly qualifies!

I should add that the model looks really good and racy fast in its bare bones state. Some would even use the term "sexy" I can hardly wait to see how it finishes up and by that I mean I wonder how the top of the plane will be treated. Will there be a bubble canopy or a turtledeck behind the cockpit area and even the shape of the verticle fin. These things lend lots of flavor and style to the already nice looking structure.

Best of all it does not seem to be over built. That counts for a lot in my book. Something else worth noting is that more than one of us feels that it may be inherently nose heavy! How many "new" designs offered up for approval can you say that about? So many I have seen look like they will need literally ounces of dead weight for ballast. Generally if one must add weight to the tail end, it usually isn't much.

Robert

No disrepect taken at all! I know this plane has a great chance of becoming a lawn dart...but you never know...and I value everyone's opinion and I did ask for them...but as Rog said earlier Dan had a Wee Stick(I don't know the dimensions) which is supposed to have a .010(I think) on it, and he put a black widow on it...and man....that thing was FAST. I had the same conerns as everyone else....nose heavy, tip stalling, and enough airspeed at launch. I believe a Black Widow weighs about 3oz(someone correct if I'm wrong). I purchased a 370mah battery from Radical RC which weighs just over 1oz and I am going to put it as far back in fuse as possible.

I have just as much fun building as I do flying, so even if this thing tip stalls on launch, rolls inverted and crashes it will still be fun and those present(most likely Rog, Dave, Raymond) will get a good laugh(myself included). I will keep updating as the progress continues...In the interest of keeping down the weight, I wasn't planning on doing anything to the top of plane(canopy, turtle deck), I just wanted to keep it simple, light as possible, and fast. Again if anyone has suggestions I am wide open to them, as I am new at this design thing. I been flying RC for 20 years and I have learned a lot just by building this plane.

-Bill

One possible option if it comes out a little nose heavy would be to use a Sure Start engine with a balloon bladder tank. It'll be lighter than the BW and shorter as well. Keep in mind you need to add washers as spacers to keep the end of the venturi off the firewall and allow some airflow.

There's going to be almost nil drag from something this small so you can shoot for that high pitch prop you've been saving for a special occasion. I'd say that a 5x4 or even 4.5x4 would not be out of the question and the speed should profit by that.

I've got a Master Airscrew 6x4 that I cut down to 5x4 with the outer portion "APC'ed" to cut some area at the tips and let it unload even more. On the couple of flights where I used it on my TeeDee powered Mustang I had Bipeflyer and CP almost cowering under the picnic tables in fear. Bipe because it was so fast and CP because he figured with all the noise that my model was going to fall apart....

Bruce, I was under the work bench helping Bipe find his contact lens.....

Bill, if the object is speed, everything has to be wafer thin. At some given mph, a wing with open panels from the LE to the spar, the covering will deform enough to become drag buckets. I don't think you can beat the approach that the 1/2A mouse racers take.......solid sheet wing and minimum frontal area fuselage. Every little extra ripple adds up to speed lost. These planes are little gems to look at.

The other thing to consider is roll control with only 14" of span, one aileron should definitely be enough and less weight to rig up. It won't take much deflection to fly the plane.

hkbii raised a good point about receded wingtips, they are slower than having the tips cut even or slightly advanced [longer in back than in front]. Good food for future thought.

If you build a clean enough airframe and prop it accordingly, it is amazing what kind of speed you can get from a Cox Reedie. When I asked around the NASS chatroom for advice before building a 1/2A speed plane, the concencus was to shoot for 90 sq inches [which I thought was nuts]. Those guys are used to the luxury of having a plane get up to 60 mph on the ground before lift-off.

Bill, a few thoughts about the AUW. You'll need to get creative! There's less wood in a Blink and Hfenn is the only person I know of to get below 7oz. My last setup included a 220mah nimh and the lightest covering I could find (It was for electrics and super light) HS-55's and a Hitec Feather receiver and it still came out over 7.5oz! I'm thinking lipo and a small esc with bec may shed some... Anyway, planning the electronics ahead of time may give you an idea of what the airframe has to come in under. For what it's worth, I think it will fly at that weight. Now, just how good are your eyes and reflexes?[sm=lol.gif]

I like the concept. The sweep will increase lateral stability - similar to using dihedral - so you can build the wing flat. It will fly better inverted. I can't tell from your photo if you have any dihedral. I also agree with keeping all the ribs parallel to the fuselage centerline like the root ribs.

The shorter the fuselage, the more critical the CG becomes, so... with the wing moved forward towards the firewall, as Bruce suggested, you can easily locate the fuel tank at the CG. Then, the CG won't change as dramatically as the tank empties near the end of the flight. Moving the wing forward will also have the effect of lengthening the tail moment which will increase longitudinal stability.

Locate the wing's mean aerodynamic chord and your balance point by adding the root chord to the tips and the tip chords to the root. Draw diagonal lines and then draw a chord-wise line through the intersection of the diagonals. Locate the balance point along the this. Sorry if you already know this.

David

Like this? Is this about where the balance point should be, or is it a certain percentage behind this point? I did some testing with lead weight to simulate the black widow and my battery pack and I am pretty confident I can get this thing to balance....


CP- Do you mean a straight trailing edge, with the leading edge tapering back? (Like a Rivets)


This is the actual wing panel of my test plane.

Bill, by receded, the tips angle in towards the belly at the trailing edge. I can see with yours', the tips are parallel to the centerline. I think the angle of the photo makes them look receded.

long thin wings slender fus with the engine turned on the side so the wing will help with the air comig off the cylinder.

it look like you have a very thick wing.

Well have you fown her yet. we would like to know lol. keep us informed

I may be thinking too far outside the box,
but if the wing was fixed <non-removable>, using bottom hatch access, he could put the aileron servo in the tail to move even more weight to the rear

Hmmmm....I thought of a fixed in place wing...but I didn't think about the aileron servo placed in the back.....I like it....I going to mess around with it a little and see if I can get it to work out....

Yeah making the wing/fuselage one piece solves some problems - but may create others. Like making sure the pushrod clears the aileron if the servo is behind the hinge line.

I had trouble with ailerons flexing on my foam combat models because I had to have the horn close to the middle of the wing since the angle of the pushrod became too great if I moved the horns outboard. But by moving the servo in front of the (glued to the fuselage) wing I was able place the horns a little farther outboard. I have no scientific proof that it actually does help but it looks different anyway.