RC_MAN

My Feedback: (11)

Our club will be hosting a heavy lift competition next year. Can someone please point me in the right direction as to what airfoil works best for this type of application. I understand the maximum wing area 1000 sg-in and max weight is 55 pounds.

Thanks again RCU members

Peter

skull1971

Wouldn't a flat bottom wing be best? The air flow over the top, in relation to the bottom would give the gratest low pressure area on top of the wing (Lift), right?

BMatthews

One of the sweetheart airfoils from the SAE competitions is the Selig 1223. But it's a super critical airfoil as far as shape goes and has an extreme rear cusp to the trailing edge. Composites only for the most part or all of this one and some snazzy engineering to ensure a 1% or better adherance to the design shape.

da Rock

What are the tasks for that competition? Is it just a simple "pick up the most weight and fly with it" type competition, or does the airplane have to do something more than just fly?

Are you permitted to have flaps? slats?

RC_MAN

My Feedback: (11)

Hi
The plane has to take off, fly a circuit and land. Slayt and flaps are OK.

Peter

Rodney

To be fair there has to be other restrictions as well such as maximum engine size, specific fuel type, maximum wing area etc.

The Internet Killer

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Tall Paul

The Eppler 423 is similar to the Selig 1223, and just a bit easier to build.
What is the competition?
55 pounds on 1000 sq. in. isn't really doable without serious construction techniques.

rmh

the qualifications seem very incomplete- given the ones as such - I would stick a ZDZ160 on it (all up 55 pounds ) and simply POWER my way around the course big n fast .---airfoil ? who cares .

of course most of these events preclude such a setup

skiman762

If they don't count the tail I would build a large lifting horizontal stab and shift the cg aft a bit
also if the flaps don't count when extended I would use some large fowlers with a screw drive to move them
also design the fuselage as a lifting body flat and wide shaped like a flat bottom wing
lots of ways to get lift she won't be the prettiest girl at the prom but she'll win the dance
with 55lbs of materal to work with you can build it strong enough thats for sure

coolbean

Just a little clarification on the 55lbs because i think it is really important..

Is the idea to
1. make the heaviest plane not to exceed 55 lbs.
2. make the plane able to lift as much as 55 lbs in addition to itself.
3. make the plane able to lift as much as 55 lbs including itself.

RC_MAN

My Feedback: (11)

Thanks for the info

My understanding is 61 size two stroke engine, 1000 sq - in wing area, plane and payload not to exceed 55 pounds.

Peter

skiman762

quote]ORIGINAL: coolbean

Just a little clarification on the 55lbs because i think it is really important..

Is the idea to
1. make the heaviest plane not to exceed 55 lbs.
2. make the plane able to lift as much as 55 lbs in addition to itself.
3. make the plane able to lift as much as 55 lbs including itself.

[/quote]

? so your looking at 110lbs total?
or 55 AUW ? 2 and 3 contradict each other

If a 61 2 stroke is the limit I would also be working on a gear drive to turn a big prop with

RC_MAN

My Feedback: (11)

#3 is my understanding.

Thanks again

Peter

skiman762

ok it sounds like the contest is who carrys the most extra weight so the lightest airplane with the heaviest load up 55 lbs that flys wins

Tall Paul

Here's 4 years of the SAE Heavy Lift competition.
Only the multi-motored planes could come close to flying at 55 pounds.
http://www.angelfire.com/indie/aerostuff/sae2000n1.htm

Edge 540

It's still amazing though how large they get with only a 61 for power!

cyclops2

I lean to copying actual real planes that DO lift a lot for their empty to overloaded weight.

JUMBO Russian freighters- Jumbo USAF freighters, Hercules -Starlifter- etc. Maybe the B-52, B 1 B2, Avro Vulcan bomber, just a guess.
Then their are a few sneakies that are small. Feisler Storch with all flaps extended. It is a real 35 mph plane.

If you can get the foils of them I am sure their shapes are very similar.

One caution. flat bottoms are faster. Undercamber USUALLY means more lift at a loss of speed. Example of this is the A-10 Warthog. It can carry as much weapons ( tonnage ) as a WW II B 17.

Form, follows the job at hand, with what is available.

BMatthews

Cylcops, those shapes rarely work for model sizes. The old scaling deal often called Reynolds number comes into play. Air plays differently at our speeds and loadings. This is why the Selig and Eppler heavy lifters look so odd if you compare them to those big lifters. Also those full sized ones need to lift AND go fast while our stuff just needs to get airborne and stay there. Different missions and thus different tools.

cyclops2

My A-10 has 30 % less undercamber at the rear compared to the Selig and the front is more symetrical. So yes I would give up some lifting ability.

However It would be totally stabile in any wind conditions or wind that lifted 1 side of the plane unexpectedly.

As I recall most people lose control or suffer wing collapse.

I have not followed this sport in 5 to 10 years.

I am sure everyone is not flying the plane anymore. They just flip switches and let the electronics and Gyros do everything.

dolanosa

The scale A10 is an airfoil that is 18% thick and has basically a permanent flaps down configuration. The B17 is a NACA 0018 which is completely different. The full scale A10's foil won't work efficiently for our use, even at 55#. In fact, the B-17 might even work better!

b

rc bugman

My Feedback: (30)

Hi,

It is very hard to beat the Clark Y with slotted flaps for 70% of the span. Takeoff run with flaps up until the last moment, drop the flaps and pop off the ground.

Elson

Johng

My Feedback: (4)

Flat bottom airfoils are best for nothing but sitting on a table, unless you need added drag (some situations you do). But air never likes going along a straight surface. I'm saying if you want less drag, more lift, etc, there is always a better solution than flat bottom.

For airfoils, the Selig or something with slotted flaps would be cool. Would also be interesting to slot the S1223.

For aircraft design, look into STOL lifters. Twin Otter, Pilatus Porter. Helio Courier. Not for lifting capability, but layout. Hint: If you wanna fly slow, you better have very effective control surfaces.

rmh

I would opt for an extremely thin , variable camber foil - coupled to a feedback system which reads weight on the wheels and then monitors in air progress - varying camber constantly to obtain best speed and constant altitude
There! see how easy that was?
I also have a design for a successful Mars rocket:

1 build a rocket
2 point it at Mars
3 Land when you get there
4 return when mission is complete

Johng

My Feedback: (4)

5 If the moon gets in the way, TURN!