HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old May 20, 2012, 07:54 PM
Registered User
livinma1's Avatar
United States, GA, Lawrenceville
Joined Jun 2003
7,565 Posts
Looks fast already Brian... Looking great man..
livinma1 is offline Find More Posts by livinma1
RCG Plus Member
Reply With Quote
Sign up now
to remove ads between posts
Old May 20, 2012, 11:27 PM
Registered User
Tumbler's Avatar
New Jersey
Joined Feb 2003
7,977 Posts
The airfoil is thicker a the tips which essentially does the same thing as washout but causes less drag....or so I am told. That is how the guy cut the wings for the Blaze and that thing doesn't seem to ever stall. Nice job with the servo covers. I have actually done the same thing with a wood plug and vacu forming plastic over it. On this particular jet I am not really looking for speed though so won't need them or gears doors, etc. Its more of a fun fly type plane. If it goes 120-130 I will be happy

Quote:
Originally Posted by ApexAero View Post
Did you wash the tips some?
Also, I sanded a small surfboard shape of foam, glassed it and split it in two then melted the foam out for linkage covers on a few fast ones
Tumbler is offline Find More Posts by Tumbler
Reply With Quote
Old May 22, 2012, 08:55 PM
Current project: Electrolyte
pdawg's Avatar
United States, OH, Dayton
Joined Apr 2004
5,479 Posts
Quote:
Originally Posted by Tumbler View Post
The airfoil is thicker a the tips which essentially does the same thing as washout but causes less drag....or so I am told. That is how the guy cut the wings for the Blaze and that thing doesn't seem to ever stall. Nice job with the servo covers. I have actually done the same thing with a wood plug and vacu forming plastic over it. On this particular jet I am not really looking for speed though so won't need them or gears doors, etc. Its more of a fun fly type plane. If it goes 120-130 I will be happy
In the case of a flying wing the washout does more than reduce the tip stall. Washout for a flying wing is used to oppose the natural pitching moment. No big deal though Brian! You will still get there by reflexing up your elevons. The Horton wings used reflexed airfoils plus progressive washout at the tips. The Northrop wings used a symmetrical airfoil with 4% washout at the tips. There are many techniques that can get you to the same place.
pdawg is online now Find More Posts by pdawg
Reply With Quote
Old May 22, 2012, 10:39 PM
Registered User
Tumbler's Avatar
New Jersey
Joined Feb 2003
7,977 Posts
The reflexed airfoil is supposed to cancel out the pitching moment from what I read. I am sure washout at the tip would help out a little more, but I just can't see it affecting pitch all that much. Again, I don't know all that much about that stuff so who knows. Either way, I have flown 8-10 deltas and they all still needed up elevator as you mentioned. Even my turbine delta needed 1/8" up elevator.

Quote:
Originally Posted by pdawg View Post
In the case of a flying wing the washout does more than reduce the tip stall. Washout for a flying wing is used to oppose the natural pitching moment. No big deal though Brian! You will still get there by reflexing up your elevons. The Horton wings used reflexed airfoils plus progressive washout at the tips. The Northrop wings used a symmetrical airfoil with 4% washout at the tips. There are many techniques that can get you to the same place.
Tumbler is offline Find More Posts by Tumbler
Reply With Quote
Old May 22, 2012, 11:09 PM
deltas are cool
AIR SALLY's Avatar
Tehachapi ,CA.
Joined Apr 2006
20,635 Posts
i've scratch built 2 delta the F-4D and the J-35 Draken .....i put a gob of reflex in the foil and my elev. were trimed almost at 0 ....now i dont know which cause more or less drag ,but both plane fly pretty good .
AIR SALLY is offline Find More Posts by AIR SALLY
Reply With Quote
Old May 22, 2012, 11:35 PM
Aka: Tom Jenkins
ApexAero's Avatar
Palm Beach County, Fl.
Joined Aug 2008
4,418 Posts
The advantage of wash at the tips is stability, it fakes a flat built wing into thinking it has dihedral and stops roll off on a loaded wing condition. IMHO: Thicker tips have more drag than thinner ones with wash out, especially on flying wings. Should you have any probs you could radius the sharp TE tips a bit and feather the bottom surface edge upward to top surface, the little tweak will do wonders.
Quote:
The Northrop wings used a symmetrical airfoil with 4% washout at the tips.
And it can go over 630 mph
ApexAero is online now Find More Posts by ApexAero
Last edited by ApexAero; May 23, 2012 at 09:18 AM.
Reply With Quote
Old May 23, 2012, 11:29 AM
Registered User
Tumbler's Avatar
New Jersey
Joined Feb 2003
7,977 Posts
Well based on the fact it has more wing area than the Blaze and will probabaly weight about 5-6lbs less, I think it will be ridiuclously floaty and don't really expect to have and stability or stalling problems. I am more worried about getting the balance right.
Tumbler is offline Find More Posts by Tumbler
Last edited by Tumbler; May 23, 2012 at 03:44 PM.
Reply With Quote
Old May 23, 2012, 02:53 PM
2014 EDF JET JAM We be Jamming
Kevin Cox's Avatar
St. Louis Intl, Missouri, United States
Joined Jan 1997
6,773 Posts
Tumbler, I was taught by the then older guys that you should include the horizontal stab atea when trying to compare a delta/wing to a conventional layout. This works well for wingloading comparisons.
Kevin Cox is offline Find More Posts by Kevin Cox
Reply With Quote
Old May 23, 2012, 03:44 PM
Registered User
Tumbler's Avatar
New Jersey
Joined Feb 2003
7,977 Posts
Even with the stab included I still think the Bullet has more area. The Blaze has a 52" wing and the Bullet is 45". Its really not all that much shorter, but the root is much larger on the Bullet, plus it has the strakes on the front. My first Blaze was 14.5lbs and I can't see the Bullet being more than 8-9lbs. So if the wing area is anywhere close to the same it is going to be a floater!

Quote:
Originally Posted by Kevin Cox View Post
Tumbler, I was taught by the then older guys that you should include the horizontal stab atea when trying to compare a delta/wing to a conventional layout. This works well for wingloading comparisons.
Tumbler is offline Find More Posts by Tumbler
Reply With Quote
Old May 23, 2012, 05:50 PM
deltas are cool
AIR SALLY's Avatar
Tehachapi ,CA.
Joined Apr 2006
20,635 Posts
man that is a lot less weight ...where does it lose the weight ?
AIR SALLY is offline Find More Posts by AIR SALLY
Reply With Quote
Old May 23, 2012, 06:24 PM
Registered User
Tumbler's Avatar
New Jersey
Joined Feb 2003
7,977 Posts
The other one was build to handle 12-14lb auw, 100mm fan, 160 controller, 12s, etc. This one has no carbon reinforcement, very minimal structure, built for new Blaze 90mm, 110 controller, 6-8s, etc. If it flys well, I would build a beefier version for 100m and 12s and would likely be in the 10-12lb range. Plus my first Blaze was waaaay over built and over painted haha. My new Blaze will be under 12lbs.

Quote:
Originally Posted by AIR SALLY View Post
man that is a lot less weight ...where does it lose the weight ?
Tumbler is offline Find More Posts by Tumbler
Reply With Quote
Old May 23, 2012, 07:37 PM
Registered User
Tumbler's Avatar
New Jersey
Joined Feb 2003
7,977 Posts
I just weighed the empty airframe and it is 3lbs 4 ozs. I know retracts and wheels are 12ozs so thats 4lbs. 2lbs for 8s 5000 lipos brings me to 6lbs. Fan, motor, esc and misc stuff another 2lbs max is 8lbs. If I went crazy with a heavy glossy paint job 9lbs total.
Tumbler is offline Find More Posts by Tumbler
Reply With Quote
Old May 23, 2012, 08:02 PM
Lee Liddle
Knife Liddle's Avatar
Carrollton, Tx
Joined Dec 2006
7,975 Posts
You are forgetting the 8oz that Murphy adds to every EDF. I never can figure out how he always gets his in there. LOL

I love the Bullet. I think you could take that fuselage and make it into a biplane and it would still look fast.
Knife Liddle is online now Find More Posts by Knife Liddle
RCG Plus Member
Old May 23, 2012, 09:40 PM
Registered User
Tumbler's Avatar
New Jersey
Joined Feb 2003
7,977 Posts
8ozs? You must build lighter than me. Murphy adds a pound to every one of mine. Thanks man...yeah if I weren't sick of molds I would mold a fuse for plug in delta wings and make this a lot easier. I am going back to ARFs for a while though.

Quote:
Originally Posted by Knife Liddle View Post
You are forgetting the 8oz that Murphy adds to every EDF. I never can figure out how he always gets his in there. LOL

I love the Bullet. I think you could take that fuselage and make it into a biplane and it would still look fast.
Tumbler is offline Find More Posts by Tumbler
Reply With Quote
Old May 30, 2012, 07:31 PM
Registered User
LuvEvolution7's Avatar
St.Catharines, Ontario
Joined Jan 2009
10,377 Posts
Quote:
Originally Posted by ApexAero View Post
The advantage of wash at the tips is stability, it fakes a flat built wing into thinking it has dihedral and stops roll off on a loaded wing condition. IMHO: Thicker tips have more drag than thinner ones with wash out, especially on flying wings. Should you have any probs you could radius the sharp TE tips a bit and feather the bottom surface edge upward to top surface, the little tweak will do wonders.

And it can go over 630 mph
The Concorde had 12 degrees of tip washout, plus thicker foil section AND a foil section change. All this to add stability, increase the effectiveness of the LE vortex and actually decrease drag at high Mach numbers.

Changing the tip section and increasing the thickness adds about the same amount of washout as a geometric twist in the wing. This does add drag at the tip, but not a ass much drag as a geometric twist. This would be more ideal on a delta than a geometric
LuvEvolution7 is offline Find More Posts by LuvEvolution7
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion St blaze Harold H Electric Plane Talk 0 Oct 19, 2011 09:13 AM
Discussion MSNBC becomes racist parody of itself MtnGoat Life, The Universe, and Politics 27 Sep 29, 2011 11:44 AM
Discussion Deciding when someone becomes a person madsci_guy Life, The Universe, and Politics 214 Sep 26, 2011 04:10 PM
Discussion Skynet becomes self aware at 2:14 Eastern time, August 29th Mr Kamikaze Australia 10 Apr 08, 2011 10:15 PM
Wanted 3.5mm Male Bullet to 2mm Female Bullet Adapter. gregoryd Aircraft - Electric - Power Systems (FS/W) 1 Mar 19, 2011 09:54 PM