Helping redesign a wing for a Helioplane. He wants to make the A/C an S.T.O.L type. Has a 230 S.I. wing and a 6 inch chord, using 09 glow power and weight looks to be about 12 OZ when finished. Ailerons are 9 S.I. each and way out at tip. No indication or outline on plans of size for real flaps.

We are hoping the A/C will take off vertically with the fuselage remaining horizontal.

However, what size in S.I. should the flaps be, and how much should they droop?


Wm.

Hello

I would recommed the following

split flaps;simpler than fowler and most seen at STOL a/c like the Pilatus Porter, Husky, etc.

about the flaps area it depends on how much lift coefficient you want, flaperon is not a bad idea when STOL abilities are needed, and 30° to 40° would be fine, flaperon can also be replaced with camber-changing ailerons if you want to fly with ailerons only.

Regards, Roderick

You aren't going to get this, or even close, without a totally new aircraft.

You would need something like the Ryan Vertiplane here with it's ability to redirect the air totally downwards from the prop blast.

Conventional flaps will help with the takeoff but you can do the same thing by just building a super light old timer design with a strongly undercambered wing. For example I have an 84 inch Flamingo with a .35 on it. AUW of 5 1/2 lbs. In a light breeze the takeoff roll is literally about 10 feet to a 30 degree climb.

If you want to experiment further with the existing model try slotted flaps. Roderick, the split flaps you suggested are mostly good at adding lots of drag along with some lift. For more lift with less drag the slotted or, better yet but a bugger to build, full spec Fowler flaps with the intermediary director flap are better for adding lift with less drag. You'll have to build the flaps up as small airfoils though. Just a flat plate won't do. And the tracks to position them are important too.

Good luck.

Well, the original thought was to make the flaps an extension of the airfoil when not extended. The, a section would rotate to the rear and down. It would be hinged to rotate about 1/2 to 3/4 inch below the lower surface. It would rotate through something like 30 to 45 degrees.

I don't like leading edge slats as the model is sort of small, and there is no room for such fabricating.

Would this work, or is something wrong with the thought?


Wm.

It still comes down to a new design if you want a truly massive advance in performance. Looking at that picture the twin props are positioned so as to direct the air blast over the top surface and into the deflected flaps and use the massive tip plates to confine the high pressure air as much as practical. So they have sort of a blown upper surface and ducted lower surface with the props feeding directly into the system.

On a modified conventional model we have a single prop spaced too far away from where the flaps are located so the blast isn't directed into the "sweet spot" . Your flaps will make some difference and teach you a lot but I doubt you'll get the full effect you think you will from an add on vs a full design.

CoosBayLumber,

Your idea of flaps hinged a little below the wing is a good way to get simplified fowler flaps. It would be best if you can get them to really blend into the wing when not deployed, but it isn't critical. For best performance, the relative position of the fowler flap and the wing can be fairly critical, but you can expect a big boost in lift, even if the positioning isn't perfect. A significant part of the benefit with this arrangement is that the flap, when deployed, increases the wing area in addition to increasing camber and angle of attack. A friend of mine built flaps exactly as you are describing, and they worked great. If you need to simplify the implementation, there is a big benefit to a large flap, say 30% of chord & as much span as you can get without taking away aileron, which deploys to 30 degrees or so. You can expect a bigger boost with a thicker wing, if you don't have to stick with an existing wing. If you do make a big flap like that, it will need a fairly beefy servo. If you need a ton of lift from the flaps, I prefer to use separate flaps and ailerons, so you can keep roll authority when flaps are deployed. For takeoff, you probably don't want split flaps, as they increase drag a lot, as was mentioned.

You may not get the kind of performance you are after, but it will be a fun project, and you can certainly get a big boost in lift.

banktoturn

I don't know if the helioplane we are talking about is kind of a strange bird to me or is it a funny name...As seen for it's weight simpler things will make life easier..for that one word:

HUSKY or anything alike

Regards, Roderick

www.sherpaaircraft.com

http://exp-aircraft.com/aircraft/slepcev/slepcev.html

the example here given for the storch is a 50ft t/o and landing rwy with 18kts for stall speed :O!!! oh and with two people standard weight people inside, 72,5 Kg each.

Split Flaps adds lots of drag without getting the plane onto the backside of the power curve so slow speed is no danger, fowler flaps can be seen at a 172 cessna, 4pax+120lbs v/s 2 pax no baggage PA-18 or a STOL aircraft, get the picture? now if you could handle to build a strong-light weight fowler flap assembly, you are quite of a genius and greetings for that.

Roderick............


Noted below is a site which has a lot of information on the Helio series. The original model of 1949 is out of production, but the variants are still being made. I am aiming to improve or alter the flying charisterics of the U-10 model version as explained above.



http://members.fortunecity.com/heliocourier/nathan2.htm


Wm.

Here's a diagram I did, of some slotted Fowler flaps, driven by a jackscrew. These could also be driven by a torque tube/bellcrank linkage.

There's also a rather well-known article and plan set, available through Model Airplane News, using pneumatic cylinders to drive them. I don't remember the details, but they were originally done for a P-38 model.

Good luck!

Some where along the line the original question got missed.

What I need to know is how many square inches the flaps ought to be and how much droop in degrees. See opening post. This is a small airplane, and many of the responces are beyond the ability of the builder to accomplish. I know him very well.


Wm.

CoosBayLumber,

It is good to know that simplicity is an advantage. It may not be possible to get the kind of performance you are after with a nice simple approach, as has been mentioned. I can't really answer in terms of square inches, as I don't know how much span you have to work with before you run into ailerons. If you make fowler flaps or simple hinged flaps from the root to the ailerons, about 30% of the wing chord, and deploy to 30 or 40 degrees, you will be getting a big chunk of what is possible with a simple implementation. If you are building a new wing, you may be able to give up some aileron span to get more flaps, depending on how the plane flies now. If you don't need to retain scale proportions, you could add some chord toward the root, and have bigger flaps.

Good luck,

banktoturn

It did kind of get missed didn't it....... Sorry.

For a good development model look to sailplanes for guidance. Most of the current sailplanes use anywhere from 17% to 22% of the wing chord for width. So for your friend's 6 inch chord this would be between 1 to 1 3/8 inch flap chord. And the span should be as long as the ailerons will permit. Not sure how big your ailerons are for span so the final sq in's will depend on how big the flaps are using the percentages above.

For max effect it can also be benificial to droop the ailerons as well. But to help prevent tip stalls and adverse yaw effects keep the aileron droop to much less angle than the flaps. I had a flaperon glider and the coupling got a bit messy when the flap deflection went past about 20 degrees. More than that and the model didn't want to do anything aileron related properly. So if you try the airleron droop only let them come down a max of 10 or 12 degrees when the flaps are down to 45 or so. If the flaps go further then leave the ailerons at the 12 degree mark. You'll probably need a computer radio for that. In so small a model it's not really practical to carry all the servos to make this work.

Flap deflections are much more easy. Takeoffs will probably work best with 20 to 30 degrees as a good compromise between lift and drag. Landings can use a full 90 degrees for very high drag and high lift.

This is a pretty small model you're dealing with. It's still a great experiment but don't be surprised if it isn't all you hope for. A 6 inch chord wing running at the speeds you're hoping for is running at a very low Reynold's number. This means the old scale factor may just bite you and not let the flaps perform as well as they would with a larger model.

Good luck and I hope this helps out.