|May 21, 2010, 02:22 AM|
2 degreess should be plenty of washout for the slope speeds the 60" should perform at. Keen to see Phil's flight results regarding handling and stall caracteristics when he gets to that stage. I'm wondering if the washout can be reduced to 0-1 degrees without to much tip stall. These little tweakes take plenty of time to determine. I think 2 degrees is a safe bet for now.
Pitty your restricted to flat land flying in your area. I think this wing will be in it's true element on the slopes. Sorry for the next paragraph!
I got another 1.5 hour slope session in today on the 48" Starfire (Arms get tied before the battery even thinks about running out). Been waiting 2 weeks for the right wind and took an early mark from work. Sweet fly, great Starfire performance again, still my favourite, but then I don't have the 60" yet! The Aussie dollar is way down at the moment, bummer.
The session was a little squarly and up to 25 knots on a 250 foot vertical cliff. A PW51 48" Starfire would have ate it up even better. Having the motor fitted certainly helps with safe launch off the cliff. Had to give it a burst at one stage as it was getting back a bit far and struggling to penatrate. That and the 2 take offs where the only time I used the motor.
Lots of inverted flying today. Inverted sloping is faster by probably 20-40% with probably equivelent improvement in lift. Strangely enouth, even hovering (same forward momentum as right way up) lift still seemed better inverted???
Once you get some performance feedback on the 60". I think the 48" optional PW51 foil will make a really nice addition to your lineup (prodomantly as a sloper). Would probably consider reducing the washout a little on it though as a speed enhancement, the increased overall speed of the airfoil should compensate enough.
|May 21, 2010, 02:29 AM|
You know about the bottom hinge as the designers build theory for the PW51 airfoil yer. Suposed to optimise the performance of the foil. Maintaining a smooth laminar flow along the entire bottom surface to maximise speed.
|May 21, 2010, 01:20 PM|
can you send me a link to the how to or the data as I am at that point where I was trying to think out that part of the layout.
I am working with some tests of size and positioning of equipment and will have some pics up shortly...
my daughter graduated today from preschool and we are still in the party mode until this evening.
(hey . . I know it is funky but it was too cool I dont know if this is an NC thing or just a newer thing graduating from preschool. . .not that it is a required part of the education process . . .but . .
wildest part of the whole thing is my Father in Law is getting another degree this weekend . . . two in cap and gowns one generation apart in one weekend - how is that for irony)
Been busy around here!
Either way . . hang with me guys, this is going to be slow starting then lightning fast once we get all the pieces together.
I had a chat with Jeff about some stuff a few days ago in regard to my original stuff fitting in . . . . we may have to drop back and rethink the motor and battery once I get the basics figured out.
|May 21, 2010, 02:31 PM|
For those of you that have been asking questions about whether big servos fit, here are my ancient JR507 std big ole gasser servos for sizing!
My rule of thumb is . . if these fit, anything will in the modern servo world.
These are just for reference, I bought a set of ultra high torque and high speed servos and loaded some karbonite gears in them for good measure.
I picked up the servo mod from a buddy of mine. I have no idea where he got the gears but the original servos are the Hecktronics high torque (144 in/oz tq) servos available from Hobby City, Deal Extreme and the like.
|May 21, 2010, 02:36 PM|
This is a 3000 mah 4S battery and it is a little big for the Mah size
I used this to get a ballpark of the height and placement of the battery and to see if I could, in fact, fit a 4s pack inside the airfoil.
I had a much different pack in mind to actually use but this helps me a lot in determining exactly how big I can go.
Here are some pics for you to see for reference.
|May 21, 2010, 07:09 PM|
Here is the links to Peter Wick threads on the PW series airfoils. If you do a find search on each page for "hinge" you will see heaps of talk about the why's of the bottom hinge.
Some of it gets pretty technical, but good info.
As to how, lots of different ways. The main point being that there is a nice consistant surface along the bottom of the foil without any bumps to cause the airflow to seperate from the surface. You can still run your servo on the top onto a servo horn mounted on the top side of the Elevons. I did that with my last small PW51 and it worked fine.
If you have trouble fitting your battery across your wing, you may want to consider a pod on the front and running it length ways. Not as clean a look, but it does allow you to keep the weight forward for your CG at minimum weight. Also leaves additional room for other components, including ballast tube on the CG if you wanted. I do pods on my main scratch built park wings (30 degree sweep) to keep the weight down and the CG forward. The other bonus is you can pad it up for impact, the protruding nose helps protect the central leading edge from inpacts. You probably want to keep the first build as the clean shape, but something to consider for later.
|May 21, 2010, 10:07 PM|
wow . .. . I have a lot to learn
been working on the 60 for a few tonight
here are some pics
Rick, thanks for the heads up on the pw51 threads, that was a lot of info to digest before I even got down to the building area to settle down to some "figurin"
I have gotten as far as assessing where we are with placement of eqp and spars and the core bed 1/2 wings are all joined to assist me in the build!
The more I do the more I realize that, although this has a lot of room, it really is light and thin . . .
I muddled around the idea of just sticking he Dons 2700 in there with a heavy 3s to make it light and fast . . . . .but I am not familiar with the pw51 to really be able to make the call as to whether that is in the best interest of the airfoil.
I would really appreciate any input from Jeff or others as to what the optimum config on the airfoil would be before we finalize the load!
Still working the old grey matter though.
|May 21, 2010, 10:11 PM|
The CG I get moving what I am planning to install around comes out to about 7" aft of the nose.
I really need a basic Cg from Jeff before I begin the final layout but this is about where we are with that.
The Spar plan is the big 10mm spar will go into the center, hopefully it will go behind the cut out for the prop.
The 2 6mm spars will go into the LE from the bottom and be flush with the bottom of the airfoil.
All spars are thick walled pultruded spars, they are about 25% heavier than the stuff I was using before so . . . .they sould be able to take a likkin and keep on tickin!
|May 21, 2010, 10:16 PM|
big ole motor
Well, I knuckled down and laid the big ole Pulso in there as the rough out to get an idea of just how big it was in relation to the top and bottom of the airfoil . . .and it is huge but could be - could be managable.
This thing has a ton of power . . .I mean big ole burley burley gobs of power.. this is a very light airplane, even if I build it super heavy it still isnt going to top 3.5 - 4 lbs. Im thinking that even if I try, this thing is going to come out in the 2.5 lb range with what I have.
I am still open to motor options . . and am still very seriously considerning whether this is really the way I want to go.
|May 21, 2010, 10:20 PM|
core beds in the drying rack
core beds in the drying rack
No, it is not a torture device for my cores! It is the core beds drying.
I bond the core beds together very accurately so that I can do the same for my wing cores when it is time. It also eliminates a bunch of materials to keep my desk more in order!
I used gorilla glue on the left side and hot glue on the right....joined the quarters together to make 2 wing halves.
I have not used hot glue in a while and the hot glue is really the ticket for this as the gorilla glue is going to take all night and use up my weights for liftin in the morning (yeah . . . like you guys believe that one!)
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