Originally Posted by Bare

Oddly.. Keith Shaw's Horten v2 manages without them... since '93 ! . and his Model flies like the Fighter Jet it was designed/intended to be. definitely not like a B17 bomber.
But he's not sharing why or how. Perhaps having a Phd plays a part :-)

Because his has a transparent vertical fin!

Flaps are cut free, hinged, and the ends capped with some 1/64" ply. I chose ply as I am thinking of keeping the ply edges "natural" to show the nature of the wooden wings of the full-scale.




This picture shows the inner flap down (angled to the left), center flap up (angled to the right) and the elevon centered. Due to the angle of the hinge-lines between the inner and central flap, there deflection is limited due to the central ribs hitting each other..


So now, other than some flap servo mounts, painting, gluing in the frise aileron hinge standoff's and glassing the root rib. The outer wing panels are DONE with construction



I also sprayed a good thick coat of primer on the Top of the center fuselage section, then spread the 3M red glazing putty over any area's of pin-holes and other imperfections. Its amazing how ugly it gets during this process:


Then installed the inlet plugs pieces and sanded the thing, then sprayed the 2nd coat of primer on:


Once the 2nd coat of primer on the top dried, I flipped the center section over and put the first coat of primer on the bottom:



Now I have to flite-metal a 40" P-51 display model for a guy, so all I will be doing on the Horten over the next few days is glassing the last few area's of exposed balsa and gluing in the elevon hinges.

Originally Posted by Bare

$64 question :-)
NO ONE knows... is the concise answer.
But need them they certainly do.
Dozens of theories floating about as to why though, apparently all incorrect... so far.
Oddly.. Keith Shaw's Horten v2 manages without them... since '93 ! . and his Model flies like the Fighter Jet it was designed/intended to be. definitely not like a B17 bomber.
But he's not sharing why or how. Perhaps having a Phd plays a part :-)

My personal opinion on the issue, is that the "norm" of EDF's (up until recently) has involved low blade count rotor and stators. Due to this, the air twists (circular rotation) through the exhaust duct and as it exits on the top side of the wing, the circular rotation causes the plume of air from each fan unit to drift to the right side of the airplane. As this air drifts over the right side of the "bat tail" it causes the pressure over the right section of the bat tail to drop, causing some drag and lift issues. These issues cause the wing to yaw and roll to the right.
My hope, is with the newer High blade count fans, this circular rotation of the air plume from the EDF unit will be slowed (or nearly non-existent) to the point where the above doesn't happen..

We are planning to strap a Ready to fly center section on the top of a friends Honda. Then put some yarn "tufts" all over the center section to record what the air currents do at 50-60mph with the EDF units off, and then again with the EDF units on. If there is any large variances in what the tufts show us, then we need to do some more investigating.

I'm also going to make anenometer type vane with no pitch to place inside the thrust tube. The reason for no pitch, is if the edf thrust plume is in fact giving a circular rotation, the vane should spin. If it does spin, then we can try putting some additional stators in the thrust tube to eliminate the rotation.

My plans are to fly this thing like a fighter! I'm not all that fond of targets, I mean bombers, so this thing will be flown like it should be, hopefully.

thank you for the explination, it all makes sense to me. it will be interesting to hear what the results are from your "experiments"

started my wings while invertmast was out flying.

About time! Now less worky worky and more buildy buildy

well, one thing we do know, is that turbine versions of the 229 don't suffer the same issues as the EDF versions. it's deffinitely a swirl issue that's interfering with the laminar flow of the upper surface. I suggested a way to virtually elliminate this in another thread, by introducing a cushion of high pressure air between the efflux columb and the flow over the wing. it would basically be vented to the upper surface in the scale vent locations immediately behind the exhaust. those vents are obviously there for a purpose on the full size aircraft, so makes sense to use them on the model too.

Originally Posted by LuvEvolution7

well, one thing we do know, is that turbine versions of the 229 don't suffer the same issues as the EDF versions. it's deffinitely a swirl issue that's interfering with the laminar flow of the upper surface. I suggested a way to virtually elliminate this in another thread, by introducing a cushion of high pressure air between the efflux columb and the flow over the wing. it would basically be vented to the upper surface in the scale vent locations immediately behind the exhaust. those vents are obviously there for a purpose on the full size aircraft, so makes sense to use them on the model too.

Yes I agree! The one thing i've been having issues with, is finding out exactly what exactly those vents are venting.. Then again, my lack of being able to come up with a set of the Bentley drawings of this thing is really hampering me in aspects like that...

Quote:
Originally Posted by SilentHunter
I played around with the LX B-2, which actually is very similar in planform to the Horten and why I bought it in the first place. It flys excellent, and uses partially deployed drag rudders for yaw stability. So maybe that coupled with exhaust vanes, frise ailerons and im sure it would be a great flier.
The partially open drag rudders increase resistance to dutch roll but probably not much better than a little more washout would. The scale H-IX makes a good slope glider but a lousy ducted fan. Ever wonder why that is? It's not the so-called "swirl effect" of the engine exhausts (although I'll concede that there could be some effect if both engines turn the same way) It's because the inlets turn the airflow so when the plane skids the air going into the ducts produces a pull in the wrong direction. Propellers also produce the same effect and that's the real reason all full size flying wings are pushers. I know a couple of engineers who have explained this effect far better than I have so I'll see if I can find one of their e-mails on the topic of power-on stability.

--Norm

[EDIT]This page from the BD-5 newsletter and the excerpts from Perkins and Hage in the link is about propellers but the intake of a duct that accelerates the air going through it has the same effect. The important thing to remember is that the turn that produces the side force happens at the intake
[/EDIT]

Another theory on the subject
Stuart

Originally Posted by invertmast

About time! Now less worky worky and more buildy buildy

get that metal p-51 done so you can get back to the horten

Originally Posted by thtaco

get that metal p-51 done so you can get back to the horten

Im working on it! As nice as it is today, i think its gonna be a sanding of the center section kind of day.

Have you decided what color scheme you are going to do? Im pretty sure imma do the winter camo.

Originally Posted by invertmast

Im working on it! As nice as it is today, i think its gonna be a sanding of the center section kind of day.

Have you decided what color scheme you are going to do? Im pretty sure imma do the winter camo.

You know I have seen so many pictures of Hortens I do not remember what that one looked like.

Originally Posted by Bare

$64 question :-)
NO ONE knows... is the concise answer.
But need them they certainly do.
Dozens of theories floating about as to why though, apparently all incorrect... so far.
Oddly.. Keith Shaw's Horten v2 manages without them... since '93 ! . and his Model flies like the Fighter Jet it was designed/intended to be. definitely not like a B17 bomber.
But he's not sharing why or how. Perhaps having a Phd plays a part :-)

Keith's Hortons (plural, the one he flies now is not the original from the '90's) have had clear plastic fins to provide the needed stability. I asked him specifically about the exhaust extensions being used on the Wingsontheweb 229 and he said in his opinion the extensions are acting as fins and the stability they provide is not from any effect they might have on the fan airflow.

all I can say for certain, is that the Vulcan bomber and the HO 229 basically had/have the same style of intakes. there are many models of the Vulcan flying that don't exhibit the same aero problems as the 229 does. the only difference is the was the exhaust exits the plane and the location of where it exits. the Vulcan exits directly behind the wings and therefore, doesn't interfere with anything aerodynamically. the 229 exits directly on top of the wing and I believe this is interfering with the aerodynamics of the surface. whether it's artificially pushing the center of pressure rearwards, or just simply messing with the way the air flows over that section is up to speculation, but putting tufts and doing some testing will be a great way to prove or disprove this. to me, it makes sense that the center section is critical in lift production and gradually decreases towards the tips. if you mess with that lift production on the most vital portion of the airframe, you are asking for trouble...............which is where many 229 flights end up.