SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Nov 22, 2012, 12:16 AM
Registered User
LuvEvolution7's Avatar
St.Catharines, Ontario
Joined Jan 2009
10,377 Posts
Hoeby

I think you may run into problems with the design above. there's so much side area ahead of the wings, that the vertical tail at that size, might not hold direction. I'm guessing you are going to need to increase the size of the tail and/or do as advised and make it into a V tail. it's very cool though.
LuvEvolution7 is offline Find More Posts by LuvEvolution7
Reply With Quote
Sign up now
to remove ads between posts
Old Nov 22, 2012, 12:19 AM
Registered User
LuvEvolution7's Avatar
St.Catharines, Ontario
Joined Jan 2009
10,377 Posts
the wings directly in front of the fans may create some problems too, in the form of loss of power. any form of turbulence will rob the fan of power, which is what you are getting from the wings. the more AOA you pull, the more turbulence you get that you must overcome. I still think it's cool though.
LuvEvolution7 is offline Find More Posts by LuvEvolution7
Reply With Quote
Old Nov 22, 2012, 11:22 AM
My project: FAIREY DELTA 1
Erik v. Schaik's Avatar
Uden Volkel, Netherlands
Joined Dec 2003
4,976 Posts
Quote:
Originally Posted by LuvEvolution7 View Post
the wings directly in front of the fans may create some problems too, in the form of loss of power. any form of turbulence will rob the fan of power, which is what you are getting from the wings. the more AOA you pull, the more turbulence you get that you must overcome. I still think it's cool though.
What percentage AOA turbulence are you thinking about and which speed range? And how much turbulence is generated close behind the trailing edge? I recon the airflow is still laminair when it leaves the wing and enters the rotor.

Feel free to start a discussion on the Uriah-Bu concept as well. Any input to make it faster will be reconsidered in the upgraded version later. IMO there isn't much left to be desired exept for possible flutter issues if this concept get pushed very hard.

br!
Erik
Erik v. Schaik is offline Find More Posts by Erik v. Schaik
Reply With Quote
Old Nov 22, 2012, 11:23 AM
My project: FAIREY DELTA 1
Erik v. Schaik's Avatar
Uden Volkel, Netherlands
Joined Dec 2003
4,976 Posts
Quote:
Originally Posted by imyohero View Post
I have a couple ideas kickin around one being an asymmetrical design.
Cool! Show us your thoughts!
Erik v. Schaik is offline Find More Posts by Erik v. Schaik
Reply With Quote
Old Nov 22, 2012, 01:16 PM
Registered User
Holland
Joined Apr 2003
145 Posts
Quote:
Originally Posted by LuvEvolution7 View Post
the wings directly in front of the fans may create some problems too, in the form of loss of power. any form of turbulence will rob the fan of power, which is what you are getting from the wings. the more AOA you pull, the more turbulence you get that you must overcome. I still think it's cool though.
I think it is only when you fly high alpha, whit low flying speed. But the modell is not designed to fly high alpha. Whit normal flying i am thinking the same as Erik does. When it is not laminair, the possible is to put a turbulence strip on the highest point of the wing profile, to be sure that the air sticks to the profile.
But i think it is not necessary

I also like to see the assymmetrical design. Please post some of your thoughts
Hoeby is offline Find More Posts by Hoeby
Reply With Quote
Old Nov 22, 2012, 02:37 PM
Lee Liddle
Knife Liddle's Avatar
Carrollton, Tx
Joined Dec 2006
8,493 Posts
Yeah, clean air is great, but, plenty of power is even better. My latest edf is a little 35mm. The fan is behind the fuselage and the wing and it still goes like stink. Of course the Th/Wt is almost 1.5/1 with about 600w per lb.
Knife Liddle is offline Find More Posts by Knife Liddle
RCG Plus Member
Last edited by Knife Liddle; Nov 22, 2012 at 03:39 PM.
Reply With Quote
Old Nov 22, 2012, 04:07 PM
Registered User
Holland
Joined Apr 2003
145 Posts
Quote:
Originally Posted by Knife Liddle View Post
Yeah, clean air is great, but, plenty of power is even better. My latest edf is a little 35mm. The fan is behind the fuselage and the wing and it still goes like stink. Of course the Th/Wt is almost 1.5/1 with about 600w per lb.
I don't think plent of power is better.

Take 600w per lb whit an airplane, which has a big front face
Or take 600w per lb whit a slick plane

I think the last is faster. I know that it is just theoretical, but it's the hobby to go fast whitout putting a heater in your plane (which all that big power is)
Hoeby is offline Find More Posts by Hoeby
Reply With Quote
Old Nov 22, 2012, 04:24 PM
Registered User
LuvEvolution7's Avatar
St.Catharines, Ontario
Joined Jan 2009
10,377 Posts
Quote:
Originally Posted by Hoeby View Post
I think it is only when you fly high alpha, whit low flying speed. But the modell is not designed to fly high alpha. Whit normal flying i am thinking the same as Erik does. When it is not laminair, the possible is to put a turbulence strip on the highest point of the wing profile, to be sure that the air sticks to the profile.
But i think it is not necessary

I also like to see the assymmetrical design. Please post some of your thoughts
yeah, but when you've got to turn to make a speed run, you've got to turn first, then you've got high alpha before the speed run starts and you've lost some of your distance covered by trying to regain what you lost in the turn. better to gain all you can, when you can.

as far as laminar flow, I would not argue that point at all. what I would argue is a thick boudary layer of sluggish air, that's gonna get ingested right into the fan. that's the issue, more than a laminar flow issue. every wing suffers thick boundary layer as it flows over the wing. if it were me, I might put vortex generators at the 70% chord mark, right in front of the intakes for the fans. this shoudl all but elliminate the thick boundary layer being ingested into the fans. just a thought.
LuvEvolution7 is offline Find More Posts by LuvEvolution7
Reply With Quote
Old Nov 22, 2012, 04:28 PM
Lee Liddle
Knife Liddle's Avatar
Carrollton, Tx
Joined Dec 2006
8,493 Posts
Quote:
Originally Posted by Hoeby View Post
I don't think plent of power is better.

Take 600w per lb whit an airplane, which has a big front face
Or take 600w per lb whit a slick plane

I think the last is faster. I know that it is just theoretical, but it's the hobby to go fast whitout putting a heater in your plane (which all that big power is)
Wow, you are assuming a lot of things there. Sure, a cleaner jet with the same power will be faster. I didn't say my jet wasn't clean, and who says that 600w per lb has to be a heat generator; it doesn't.
Knife Liddle is offline Find More Posts by Knife Liddle
RCG Plus Member
Old Nov 22, 2012, 04:31 PM
Registered User
LuvEvolution7's Avatar
St.Catharines, Ontario
Joined Jan 2009
10,377 Posts
Erik, would there not be more speed to be gained if you moved the intake a bit further forward on your plane? maximum pressure is attained where the fuselage is at its widest point, therefore, it would make sense that the max inlet pressure would be attained at the widest point of the fuselage too. it's my thinking that you could gain a bit of extra thrust at the inlets by moving them forward to this point. basically, it would be free speed on the same amount of power.
LuvEvolution7 is offline Find More Posts by LuvEvolution7
Reply With Quote
Old Nov 22, 2012, 05:04 PM
My project: FAIREY DELTA 1
Erik v. Schaik's Avatar
Uden Volkel, Netherlands
Joined Dec 2003
4,976 Posts
Good point! That would reduce the FSA for a cilindrical nacelle as well minimizing the over pressure in front of the nacelle (it didn't came up to me using the wing thickness to reduce the FSA and use the fuse for higher efflux into the intake!)

I used the glass cloth structure like a golf ball surface to reduce the boundary layer and obtain max reflextion of sunlight at all angles for visibility which works great. Tough the surface is pretty smooth it goes like stink with only a 2w20 at 4s.

@ Lee,
You need a slick model before adding lots of power. Adding power isn't for free (shorter flight time, more capacity, bigger ESC, higher wingloading etc)
Erik v. Schaik is offline Find More Posts by Erik v. Schaik
Last edited by Erik v. Schaik; Nov 22, 2012 at 05:12 PM.
Reply With Quote
Old Nov 22, 2012, 05:09 PM
My project: FAIREY DELTA 1
Erik v. Schaik's Avatar
Uden Volkel, Netherlands
Joined Dec 2003
4,976 Posts
Quote:
Originally Posted by LuvEvolution7 View Post
yeah, but when you've got to turn to make a speed run, you've got to turn first, then you've got high alpha before the speed run starts and you've lost some of your distance covered by trying to regain what you lost in the turn. better to gain all you can, when you can.
That's why the thrust/weight ratio needs to be high to accelerate in vertical climb as well. The angled intake I used is about the best for high alpha/max thrust and good for high speed/low AOA as well. In turns the intake on top of the wing does feed the fan where the bottom part starves. This idea came from an F15 intake, mirrored on both sides of the wing

Turbulators are nice for experimenting!

br!
Erik
Erik v. Schaik is offline Find More Posts by Erik v. Schaik
Reply With Quote
Old Nov 22, 2012, 07:47 PM
BVM Viper Fever
pdawg's Avatar
United States, OH, Dayton
Joined Apr 2004
5,558 Posts
I would thoroughly enjoy competing against some of you in fixed power system speed event. Not sure its possible online (too much drama) but it would sure put a smile on my face to see what looks cool vs. what is actually fast.
pdawg is online now Find More Posts by pdawg
Reply With Quote
Old Nov 23, 2012, 01:21 AM
Registered User
Joined Nov 2012
2 Posts
fastest edf jet

i just joined this group and came across this topic. i don't think this meets your requirements but it is a edf just not a scratch built one. i maybe wrong but, i remember reading last year that Terry Nitch & his Bob Violett E-Bandit was hitting somewhere around 218mph+ at a jet rally. that's SCREAMING fast. then again at a price tag of $3,000.00+ it should be fast. flying any type of jet be electric,nitro,or turbine takes some pretty good skill. hitting speeds of 125mph+ is a whole other ball game, pushing my skill level for sure. with a plane weight of 4lbs+ and that kind of speed, when accidents happen (and they do) they no longer are airplanes but WEAPONS OF MASS DESTRUCTION. . was just a few months ago at a local flying field, i watched a guy take his scratch build edf and try to tunnel his way to the earth's core. he was doing some high speed power dives. the last one he dropped in from about 300' came shooting almost straight down when disaster struck. couldn't figure out if it was a mechanical or electrical failure, cause there wasn't a piece bigger the 8". the plane smacked the ground nose first at full power ( i think it was a 4s setup). we found pieces of his plane almost 50 yds away.
jds98zj is offline Find More Posts by jds98zj
Reply With Quote
Old Nov 23, 2012, 12:47 PM
My project: FAIREY DELTA 1
Erik v. Schaik's Avatar
Uden Volkel, Netherlands
Joined Dec 2003
4,976 Posts
Hi Jd!

Welcome to this forum!
In my "tunnel" vision e-bandit type planes are simple copies of piloted aircraft. The downside of these designs is they need to have room for a pillot thus compromises have been made for the power system. IMO the bifurcated intake designs are the stupidest construction ever made up for edf jets and a big loss in efficiency. Tough they claim to fly very fast with insane power levels and costs I don't think this concept is ideal for high speed simply because these planes have been designed for ease of production and high sell rates. Going for high speed has nothing to do with these concepts because there are only limmited skilled builders and pilots who can cope and understand these planes.

Weapons of mass destruction is all relative. I had footage on my HD of a 900gr edf jet hitting a concrete wall and left a nice hole in it. Seen flesh wounds to the bone made by a shockflyer too so where do you draw the line? 218mph seems fast for you but most of us in this thread do fly models close to 200mph half the size of e-bandit.

Boy I do hope if I crash my plane it goes down very deep which saves me a trip to the bin
Erik v. Schaik is offline Find More Posts by Erik v. Schaik
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion How do you guys feel about Nitroplanes? (The company) rckatz Nitro Planes 36 Nov 29, 2012 05:33 PM
Question Question about flying wing CG and how it might be affected by adding a fuse daronj Foamies (Scratchbuilt) 2 Jul 01, 2012 02:10 PM
Contest Hobby Lobby Lynx Speed Contest!!!! CONTINUED NEW Current top speed is 139.6 mph! dpowellmeii Pusher Prop Jet Models 7 May 21, 2012 12:52 PM
Rave How about a Tiger Moth gliding contest? swooper GWS (Grand Wing Servo) 3 Nov 08, 2003 04:09 PM