bdb5

My Feedback: (5)

PLease explain then to me, if youi have the time

bdb5

My Feedback: (5)

I read the rules, still don't get it???

Ben Lanterman

bdb5 - The rules (which I can't load for some reason) have given the students a set of requirements. From what I can gather by just reading this thread the airplane has to fit into a box of a given size. Apparently there are points for taking the airplane out of the box and setting it up. The airplanes need to carry weight or something similiar. Takeoffs have to be within a certain distance. Presentations are made to a judging panel. Power plants are restricted.

It is not just fly around in a circle with any airplane. With all of those limitations imposed on the design you end up with one similar to the one shown. Of course it is not the only design possible but it is a viable one.

The average airplane at the flying field doing 3D, etc. will fail in a most gruesome manner in one or more of the requirements.

Once you have the airplane loaded and flying you find that making just a few circuits aboutl the field is a real challenge, not just a trivial thing.

I think TallPaul expected you to work this out if you had read the rules.

Tall Paul

The AIAA plane is electric powered.
The power pack can weigh 5 pounds.
The 2003 plane must carry another 5 pounds. (2002 it was 24 softballs)
The plane must fit in a 1x2x4 foot box.
It must take off, fly several laps including a 360 degree turn each lap.
Basically there's 18 to 20+ pounds to be considered, that has to take off in 120 feet.
These are difficult requirements.
There's a high-point count task which has the plane fly the laps -and- release the payload "autonomously" after landing.
This adds complexity.
.
SAE requires a specific motor, and a wingspan limitation. 6 feet, very short.
The plane must take off within 200 feet, do a 360 (2 180s) and land.
Again, these planes will gross out over 20 pounds. Airframe weight is not considered as part of the score. The amount of weight added counts.
A simpler task, but stretches the limits of the plane's controllabiliity because of the need to carry more weight than anyone else.
AIAA doing the task at all is a feat.
SAE predicting and achieving the predicted weight matters more.
There is no similarity between 3D flying and lifting. Although some of the terminal attitudes achieved before impact in lifting are similar.

Jeremy Sebens

The airplanes are scored on several factors. A mission score is made up of the following formula:

Difficulty Factor/(Mission time+assembly time+Rated Aircraft Cost)

The assembly time is the time it takes the team to remove the airplane from a 1'X2'X4' box and assemble it into a flightworthy condition.

The Rated Aircraft Cost (RAC) is based on a complicated formula involving the size, wieght, and propulsion system of the aircraft.

Our aircraft has been designed to trade of between these requirements in the hopes of maximizing our score. It goes together quickly, has a moderately low RAC, and flies pretty quickly. Based on the new, improved flying qualities of the aircraft, I expect we'll do well at the competition.

More later, but I've got to go fly it now!

And it's not unconventional - just stubby. There's still an engine up front, a wing in the middle, and a tail in back - it's just the proportions that are odd.

Please try not to criticize the design work of what I consider a talented group that it has been a privilege to work with unless you understand the (extremely complex) mission requirements. There is a very good reason that a Pilatus Porter (which our airplane vaguely resembles) looks different from an Extra 330L. Neither would perform the other's mission well.

Tall Paul

The U of MD is flying.... kinda...
http://www.rcuniverse.com/showthread...952&forumid=59]

matlok

Hey guys -

Looking great!..... I think most people who see this stuff don't realize how much work goes into it, especially design-wise. There's just a lot on the table to deal with and still be competetive. I was on the MSU team last year (builder/pilot) but have trasferred to another school and won't be competing anymore. I really wish I could do it again though....

Good luck with the contest!

Jeremy Sebens

Hey there, Matt! It's Jeremy! How's life these days?

Guys, matlok was the only reason we actually got a plane in the air at MSU last year - he put in far more work on the construction than anyone else on the team - including me. He also did a great job of piloting the aircraft to a great finish considering her endurance troubles.

matlok

Hey dude! I didn't even realize it was you! So howz things at IL?? Looks like DBF is going great. I transferred to DSU to do Flight Ops, and right now I'm about 2 weeks away from my Private checkride. Almost done w/my big Edge too - I've had a few projects in-between plus school and work, so that's why she's not done yet. I'll have to send you some pics when it's finished. Speaking of pics, do you have any from last year you can e-mail me? The only ones I have are the 3 from the AIAA/DBF website.

I'll mail you later - good luck again!

Matt

MarkVZ

Hey guys..

Your school's plane looks great Jeremy. I like the looks of the taildragger configuration.

Here at Mississippi State U we're almost finished with our 2nd plane. Ater the tragic loss of our prototype (which you saw firsthand, Jeremy) our 2nd plane will be finished now just a mere 2 weeks from start of construction. We've cut nearly 3 pounds from our previous weight and our assembly time is a fraction of what it used to be. Needless to say we used a different wing joiner assembly I also made a new cowling assembly which makes this one less boxy.

Well back to Patterson until late tonight.. we've gotta get this one in the air by this weekend. My life is covering for the next few days

Jeremy Sebens

Where'd you guys cut the weight? 3 pounds is a LOT! Well done! That puts your plane right at the same weight as ours. We've still got a bigger wing, though, so NYAAAAH!

Did you get the warp pulled out of that wing OK? Ah, the joys of Monokote!

I'm looking forward to seeing you guys at competition. This year should definitely be interesting. Tell everyone hi for me.

matlok

MarkVZ,

Sorry to hear about the first plane, but man that's great y'all got the 2nd one going so quick! If you don't mind, e-mail me and let me know when ya'll plan on test flying again - I'd like to come watch and see how ya'll are doing! Tell Viva and everybody I said hi.

Matt
[email protected]

MarkVZ

Hey guys..

It looks like we'll be a predicted 2.25 pounds under the weight of the last plane after concluding my work for the night. I got the wings covered and trimmed and we're closing in on the fuselage. I was up there for 10+ hours today, which is not an uncommon thing lately.

The 2+ pounds came from several places. The main thing was our switch to a carbon-fiber tube wing joiner assembly. We eliminated our center-section all together and the wings plug into the fuselage.

I re-designed the tail from the trailing edge rearwards, constructing it fully from balsa, and it turned out stiffer and lighter than the former lite-ply assembly. We used thinner sheet pieces in the wings, and just generally did things right the first time, which means less glue

The wing structure is so much stronger now. We stacked 25+ pounds of weight on the fuselage and picked it up by the tips no problem. I love carbon fiber

The slight warp came out of the left wing after we soaked the LE sheeting, jigged it and heated it with a high-temp heat gun. Thanks for your advice.

You can watch our progress on this page which Bryan made for us:

SWAG Building Marathon

Mike, I'm putting in a full day tomorrow in hopes of taxi testing Friday and flying on Saturday. Give us your number and we can let you know.

I'm looking forward to competition as well. I'm really interested in seeing how other teams handled the design constraints and how we could have done thing better.

MarkVZ

Oh, by the way, are we allowed to use spinners according to the rules? I don't feel like digging through the ambiguities that are the rules right now

Jeremy Sebens

I don't see anything in the rules that prohibits them. Can't see why they'd be banned, either...

Tall Paul

AMA requires spinners. You might be prepared..

Jeremy Sebens

Apparently this requirement is normally relaxed a bit, as it's been about 50/50 with and without spinners for the past two years at least.

MarkVZ

Good news (for us anyways)

Today, after 2 weeks to the hour since the big boxes of balsa arrived, we have flown our 2nd DBF competition aircraft. She handles beautifully and completed all missions as planned. All that's left now is a little more Monokote trimming and a few other small quirks to work out.

If the weather holds we will continue flight testing tomorrow. Bryan should have pics up of the finished aircraft shortly.

Jeremy Sebens

I just got back from an entirely successful test-flying session as well. We've been running dawn patrols for the past couple of days as the weather at our flying field (The old AFB in Rantoul, IL)is a bit sporty except in the wee hours of the morning.

Yesterday's flight went quite badly as I tried wrestling the plane off the runway with a reduced-power pack and a full load. The plane got onto the really bad end of the power curve and sank in for a "landing" that would have been properly dubbed a crash for most aircraft. Luckily the Belle is descended from a bulldozer, and suffered only superficial damage. We patched her back up and rolled out for another early morning round, with Mike Cross flying one more check flight, this time with our beautiful shiny new competiton packs. Everything went well, and I went on to fly another seven or eight flights, including an energy trial. Everything seems to be ready in all respects, except for the pilot (that would be me), who just needs a bit more time to get 100% dialed in to the airplane.

Let me tell you, with a bit of altitude to dive in from, this plane *screams*. To penetrate upwind in the 15-18mph winds I was flying in, I pointed her down on upwind. Groundspeed was perfectly acceptable, and I'm guessing that the airspeed may have topped 100 mph. Not too shabby for a cargo beast.

Anyway, a few more flights early next week, and we're ready for departure on Thursday. I can't wait.

Tall Paul

Good luck! Take lots of photos of the other guys and post them...

Jeremy Sebens

"Junior" looks great! The new nose is definitely a cosmetic improvement. Could make a big difference aerodynamically, too. Does it fly any faster now?

Whose turbine is that? Nice chase plane! Or is that Plan B:

Judge: What's that noise? Sounds like a jet!

MSU DBF team: What noise? Don't all electric motors sound like that?

MarkVZ

Jeremy,

Sorry to hear about the bad landing. I'm glad to hear it survived though. Sounds like your plane is a bit more durable than ours. When we picked up the remains of our first aircraft, we found that the assembly box nicely doubles as a casket. It took us a while to get all of the mud and little balsa bits out of it, though

The turbine belongs to the father of our pilot Will. He provided us great entertainment as we waited for our batteries to recharge. It is equipped with thrust vectoring and can do some wicked maneuvers.

Thanks for the compliments on our plane. I think the new nose is a great improvement as well. You should have seen how nervous Bryan was when David and I took the fuselage downstairs to the bandsaw and went at it

Here's a few images of our plane for those who are not checking the photos page:









After another few hours with the Monokote iron, our 2nd plane now features a sharks mouth like the first one. We will continue to flight test the aircraft Monday.

Tall Paul

Mark, looks good! I'm presuming the inlets are for battery cooling?
What's the flying weight?
I see it's flown with and without the "antenna"... any noticeable handling differences?

MarkVZ

Paul:

Yes, the inlets are for battery cooling. The batteries used to be placed above the box in the fuselage, but we encountered a nasty tip-over problem on the ground because of the high CG. This tipsyness problem earned our pilot a set of small wingtip skids on this plane which I love to rag on him about. So anyways I pulled the packs out and built pods for them outside of the fuselage and it works well.

Flying weight is 13.25 pounds emtpy, 18.25 with box, and 19.25 with box and antenna.

We did wind tunnel testing on an old fuselage (Carbon Goose's first fuselage btw) to determine the wake created by the antenna. We used these numbers to design our tail. Our antenna is placed right over the CG and our pilot reports that he can not feel any aerodynamic effects resulting from adding the antenna. For us it's just an extra pound to carry. The whole H-tail design is to avoid the wake produced by the antenna.

MarkVZ

Oh, and by the way, our school wanted to do a twin-boom design like yours for optimal antenna placement, but it is in defiance of the rules to have part of the aircraft's structure obscure the 360 degree "view" of the antenna. I think the only exception is wing struts or landing gear legs. I'm not sure if the SAE competition has different rules, but your A-Tail design would not be legal with the antenna in that position.