How do I size a delta?
06-11-2008, 07:39 AM
#1
Member
Thread Starter
My Feedback: (2)
Join Date: Oct 2002
Location: Graham,
WA
Posts: 95
Likes: 0
Received 0 Likes
on
0 Posts
How do I size a delta?
I've got a K&B 20 sportster and a sheet of 2" pink foam just screaming to become a delta. My only problem is I can't seem to find other deltas of similar power requirements to either imitate or take size cues off of. It doesn't need to be super-fast, just a general sport flyer. How do I decide on the span and sweep? Even the wing loading is different than regular models and I don't know what numbers to use. Any suggestions? Thanks.
Brian
Brian
06-11-2008, 10:10 PM
#3
Join Date: Oct 2002
Location: Chilliwack, BC, CANADA
Posts: 12,425
Likes: 0
Received 22 Likes
on
19 Posts
RE: How do I size a delta?
Use wing area as your method for sizing it. But remember that with any flying wing, and a delta is a flying wing, you should size it a little larger. For the .20 I'd suggest 450 to 500 square inches of area is about right.
06-12-2008, 01:51 PM
#5
Member
Thread Starter
My Feedback: (2)
Join Date: Oct 2002
Location: Graham,
WA
Posts: 95
Likes: 0
Received 0 Likes
on
0 Posts
RE: How do I size a delta?
Coos, You mentioned the Hustler had a thick airfoil section. Do you recall how thick? Did thick airfoil allow for tighter turns and not bleed off as much speed? (It seems odd to see a delta as a pylon racer, and I can't imagine it was terribly great at it compared to traditional winged aircraft. Maybe for a class only composed of deltas?)
I'm looking for basic sport flying, but I am sort of limited to a 2 inch thickness of my foam. I hope it isn't too fastI'll just prop it slow.
BMathews, With some sketching it looks like 18 inch root, 6 inch tip and a 20 inch half span would get me 480 sq inches of area. That's a good size (for transportation) and the sweep isn't anything extreme. I'll see how much foam I have...
I'm looking for basic sport flying, but I am sort of limited to a 2 inch thickness of my foam. I hope it isn't too fastI'll just prop it slow.
BMathews, With some sketching it looks like 18 inch root, 6 inch tip and a 20 inch half span would get me 480 sq inches of area. That's a good size (for transportation) and the sweep isn't anything extreme. I'll see how much foam I have...
06-12-2008, 02:26 PM
#6
My Feedback: (65)
Join Date: Dec 2001
Location: Orlando, FL
Posts: 899
Likes: 0
Received 0 Likes
on
0 Posts
RE: How do I size a delta?
Here is a good web site to give you some ideas. Herb's 86" delta is powered by a .46 so you could size yours based upon down-sizing his.
http://www.flybyphotography.com/CrazyHerb/index.htm
http://www.flybyphotography.com/CrazyHerb/index.htm
06-12-2008, 03:28 PM
#7
Member
Thread Starter
My Feedback: (2)
Join Date: Oct 2002
Location: Graham,
WA
Posts: 95
Likes: 0
Received 0 Likes
on
0 Posts
RE: How do I size a delta?
Thanks RAMFlyer, I have been to his site before. Great resource. I was just confused as to the sizing requirements of deltas. I am familiar with regular plane types, but for flying wings I don't know if special rules apply.
The "JacksDelta" on CrazyHerb is close, but may be too large for my .20 engine. From what I've seen on RCU, it appears I could put any size engine on almost any size delta to get whatever performance I want, I just didn't know the relationship. But I guess it all comes down to wing loading. I imagine those numbers aren't much different between regular or delta wings.
Thanks for the insight.
The "JacksDelta" on CrazyHerb is close, but may be too large for my .20 engine. From what I've seen on RCU, it appears I could put any size engine on almost any size delta to get whatever performance I want, I just didn't know the relationship. But I guess it all comes down to wing loading. I imagine those numbers aren't much different between regular or delta wings.
Thanks for the insight.
06-13-2008, 01:01 PM
#8
Senior Member
My Feedback: (1)
RE: How do I size a delta?
Per attached, this is what the delta wing XD-7 Hustler by Midwest looked like. Has big S.I. area, and it has about 3" Max. thickness at centerline. It was originally designed for the big Bonner servos, thus need for the thickness and height.
Designed for HOT .19 to .20 glow engines.
Wm.
Designed for HOT .19 to .20 glow engines.
Wm.
06-13-2008, 02:20 PM
#9
Member
Thread Starter
My Feedback: (2)
Join Date: Oct 2002
Location: Graham,
WA
Posts: 95
Likes: 0
Received 0 Likes
on
0 Posts
RE: How do I size a delta?
Wow, does that ad say the Hustler was a 5lb plane? That's heavy for a 20. I'm thinking with a 1" thick all foam delta I should be hitting the 1.5-2 lb range. Maybe VTOL?
Although it is nice to know that if it comes out heavy, it should still fly. I've cut foam and getting ready for component placement. I should be able to get some pictures up this evening.
Brian
Although it is nice to know that if it comes out heavy, it should still fly. I've cut foam and getting ready for component placement. I should be able to get some pictures up this evening.Brian
06-14-2008, 05:25 PM
#10
Senior Member
My Feedback: (1)
RE: How do I size a delta?
Where did you get that 5 pound number from?
The text on article states 3lb. 14 Oz. and that was using the older (era) servos and radio gear which weighed like 1/2 pound each. The one I built came in substantially less than the scheduled weight. Used modern radio gear, and modern higher powered glow engines which even weigh les than their earlier counterparts did.
Wm.
The text on article states 3lb. 14 Oz. and that was using the older (era) servos and radio gear which weighed like 1/2 pound each. The one I built came in substantially less than the scheduled weight. Used modern radio gear, and modern higher powered glow engines which even weigh les than their earlier counterparts did.
Wm.
06-14-2008, 11:23 PM
#11
Member
Thread Starter
My Feedback: (2)
Join Date: Oct 2002
Location: Graham,
WA
Posts: 95
Likes: 0
Received 0 Likes
on
0 Posts
RE: How do I size a delta?
Coos, I believe the yellow boxed area of the earlier pic shown below says "Midwest Hustler kit was 5lb 6 oz..." I may be mistaken though. I knew it sounded way too high, but I didn't see anything else about it. Sounds like yours was quite a performer. I love the fact that newer (smaller and cheaper) radio gear is making small models even more practical.
Brian
Brian
06-15-2008, 08:26 AM
#12
Senior Member
My Feedback: (1)
RE: How do I size a delta?
No... Original advertisement says that Dale Nutter managed to get his trimmed down to 3 pounds 6 ounces from the basic 3 pounds 14 ounces. Your reading is about two pounds off. May be in the scanned representation here too.
Mine came in at two pounds 14 ounces without fuel. But the glow motor was overall lighter (even with muffler) by about 1-2 ounces, and the radio gear came measured in Grams not ounces. Never have thought it, but this chopped a whole pound off basic model. Still does not make up for my poor flying ability. I round the curves too wide, and stay too high in the air. New motors put out so much more poop than ones of 10-20 eyars ago. Much less way back when.
Wm.
Mine came in at two pounds 14 ounces without fuel. But the glow motor was overall lighter (even with muffler) by about 1-2 ounces, and the radio gear came measured in Grams not ounces. Never have thought it, but this chopped a whole pound off basic model. Still does not make up for my poor flying ability. I round the curves too wide, and stay too high in the air. New motors put out so much more poop than ones of 10-20 eyars ago. Much less way back when.
Wm.
