Propeller referenced above (too late to edit it in to the previous post)
Thundergull
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Speedboat100
Well-Known Member
Cool...what a ride !
I recall mr Jim Bede had an idea to use the BD-5 fuselage also for a glider. I cannot think of much more than 20-25 ft as a span for it.
It is about aspect ratio, total drag and power to weight ratio and wing loading...if those number are still good you can fly it at 250 lbs pilot very well...but if the plane is 800+ kg like some carbon gliders are...it certainly no longer can be small in any measurement.
Thank goodness it was an RV-3 aircraft. One of a very few that fly just as well power off as power on.
Speedboat100
Well-Known Member
No you don't. Because the moment you turn off the motor, it's not much of a glider.
L/D performance is dependent directly on span and equivalent drag area. Minimum sink rate is dependent upon aircraft weight, equivalent drag area, and span loading.
Note that "span" figures into both of those critical glider-related performance parameters. A 20' span "glider" isn't going to be much of a glider unless it's exceptionally light and clean - in fact, it'd have to be a model, just like VB is saying.
Physics doesn't care what we want. If you want to design airplanes, Topspe... er, Speedboat100, you have to go beyond pretty drawings and start doing the math.
pictsidhe
Banned
I can see what caused the problem. The prop was a little out of balance.
pictsidhe
Banned
Pffft, maths is only for people who need stuff to actually work.
Oh, THAT.
Hi, no response to e-mail or phone from here. Peter has bought a plane and is cheerfully commuting Cowra/Canberrra/Orange (J170, I think). So curses, I don't get to build one with/for him. Back to dreaming.
jedi
Well-Known Member
Mark responded to an email sent to thundergul@aol.com.
There is a complete Tornado kit (knock-off of the Gull) for sale... very reasonably priced... on the San Diego Craigslist if anyone is interested.
If any HBA member buys and builds this Tornado kit, please understand that a heavily armed HBA Delta Force team is standing by with direct orders to shoot on sight if the builder uses the "Wicked Witch Hat" Titan version of the nose cone.
It's just an unforgivable crime against aesthetics.
If any HBA member buys and builds this Tornado kit, please understand that a heavily armed HBA Delta Force team is standing by with direct orders to shoot on sight if the builder uses the "Wicked Witch Hat" Titan version of the nose cone.
It's just an unforgivable crime against aesthetics.
Seawarner
New Member
I corresponded With Mark briefly a few years back. He said that 250 Lb pilot would be no problem with soaring wings. He did a staggered tandem version too.
Seawarner
New Member
Hi Craig
The Load limits are 6+ 4- and we have tested the wing to failure. It yields as a bow in the wing and fails at the aileron flap juncture as it was designed to do. Every structure has a failure mode and I wanted it to fail in a manner that would present the best stability and clearance for the ballistic parachute, if you install one.
All the models are designed to the same limits and characteristics.
The power system complete with battery's and all is currently $13000 The Soaring Gull 2000 kit is $14,590.
Yes the electric power system should be purchased last.
The wing structure is a Dcell with the wash out built in, in our jig. The Dcell ribs are foam bonded in to the Dcell. The main spar is built up of aluminum angles riveted and bonded to a shear web. The aft ribs are formed from aluminum sheet. and the wing skins are of varying thickness sheets in relation of the local load. The skins are riveted and bonded.
The airfoil is my own design, the product of 20 years of study and 10 tests by taking a wing on a flying airplane and changing the airfoil by cutting the new shape out of foam and attaching it to the wing and measuring its characteristics.
It generates a lift coefficient of 2.0 as compares to the Cessna at 1.6 and the average ultralight at 1.1 this means that my wing only needs to be 1/2 as big as, say a rans for instance.
I am still studying ducted fans but I don't think that they are ready yet for prime time.
I really like Joby motors and will be spending several days at his place this week end doing testing and design work with him, JoeBen.
The Internet is a wonderful source for design information.
290# is not to much but I would encourage you to loose some weight since it takes power to lift every pound.
I hope I answered enough of your questions for now, feel free to ask whenever you come up with more questions.
Happy Flying
Mark
Speedboat100
Well-Known Member
This was a good advice. I got it now at 36 ft span.
And you know that is the right amount for how much performance, exactly?
My point wasn't "make the wings bigger." My point was that you need to (learn and then) do the math so that you can calculate how much span you need to obtain a particular performance goal. Eyeballs and guessing isn't going to get you there.
Do yourself a favor and buy at least this book. It will be a very good beginning, isn't expensive, and the math is not difficult:
My point wasn't "make the wings bigger." My point was that you need to (learn and then) do the math so that you can calculate how much span you need to obtain a particular performance goal. Eyeballs and guessing isn't going to get you there.
Do yourself a favor and buy at least this book. It will be a very good beginning, isn't expensive, and the math is not difficult:
Speedboat100
Well-Known Member
I already have a book.
But I really hadn"t read it too much. Now I did and got it right. Raymer and Torenbeek with Roscam and Howe are pretty much aligned now in my design. What I am tuning is the LG mechanism and poor man area ruling.
But I really hadn"t read it too much. Now I did and got it right. Raymer and Torenbeek with Roscam and Howe are pretty much aligned now in my design. What I am tuning is the LG mechanism and poor man area ruling.
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