Update: the beast has been tamed!

Mario's Tamed Horten HO229 Flying Wing (3 min 5 sec)

Hi,

I'm building a new version of the Horten I destroyed recently.
For history on that one, including plans, pictures and videos, go to www.rcgroups.com/forums/showthread.php?t=2015825

The specs will be very similar to the previous one, but I'm dramatically changing the construction method and materials.
This time I'm building it out of solid high density foam, cutting parts with a hot wire using the ribs in the plans as templates.

I'm also using a friend's CNC machine to cut the wings (R5 to R11 in plans), but it could also be done manually with a hot wire (and a bit of patience and sanding).
I went down the CNC path as it was a lot easier easier to get the tips washout in place.

Here are some pictures.

One to watch.Ive long thought this would be the best way to build a foam IX.
Which plan/size/fans?

Hi Stupot46,
Glad to see you again

Same as the previous one.
Plans on the link in post #1.

Size: 1200mm
EDF: 2x 64mm with 4800kv motors

Weight will probably be a bit heavier but those EDFs/motors deliver so much power that I'm sure it'll be fine.

This version, though, will have 4 degrees washout and 3 degrees thrust line incidence. Hopefully it will be easier to slow down than the previous one which had nearly zero washout.

Also, the solid foam should make it a lot more sturdy.

I'm considering the possibility of adding flaps to this one... Any thoughts?

Some progress tonight.
Battery hatch, sanding and gluing scheduled for tomorrow.

Subbed

Nice work!

Senor Flowers' dwg has 1/2 the wing tip twist that it should have.
That... is what defeated him, causing him to abandon the effort
Epoxy/glass Or Balsa Skins?
Time for Mk 2 inlets / edf covers as well ?
Flaps are a very complex mix, creating unnecessary complications imo..unless a scale fanatic. Adequate twist is more important imo.
Don't forget spars, either carbone rtubes or full depth I beam wood.
I've found that Dow (blue) extruded polystyrene foam sands very Much better.

Hi Bare,

Yeah my previous Horten had too little twist and I think that's what go me.
It flew nice and stable as long as I flew it fast, but it became unpredictable at lower speeds.

This one will have the -4 degrees washout in the tips, as per plans following the original.
Are you suggesting I should have -8 degrees instead?

No skins. The whole thing is solid foam cut with templates. I know epoxy or glass will make it sturdier but there will also be a weight penalty. I'm expecting tis one to be around 1.3 kg so I don't want to go beyond that (the previous one was 1.1 kg).

I'll put CF spars after gluing the wings. They wii fit in channels cut at the bottom so they don't interfere with the battery/ESCs hatch.

7 degrees for sure... 3.78 degrees isn't even worth continuing the build with imo..
Also note that the 13% centre rib thickness is odd as well
Remembering the 'original' design/plan was a... discouraging failure... for it's owner/designer :-)
1.3 kgs is no lightweight IMO you could easily manage an Epoxy /glass skin within that.

I think I'll increase the twist. I've got 4 degrees at the moment, but I should be able to increase it with a bit of heat forming in the tips.
Not overly concerned about the rest, as the previous version flew very well.
The only problem seemed to be stability at lower speeds which I'm expecting will be fixed with the proper washout.

More progress.
Battery hatch/lid done.
Centre hub glued and drying.
Next step will be cut and glue the wings.
This build method is a lot better than the previous one.

Originally Posted by mperaltaoz

I think I'll increase the twist. I've got 4 degrees at the moment, but I should be able to increase it with a bit of heat forming in the tips.
Not overly concerned about the rest, as the previous version flew very well.
The only problem seemed to be stability at lower speeds which I'm expecting will be fixed with the proper washout.

Good plan. But.. can you do so and still retain a straight elevon hinge line ?
Did you open the throttles to max.. much or at all, on the previous build ?
Flat sheet depron winged 'sorta Hortens' seemingly fly very well at lowish speeds too.
Alfons Gabsch only builds hortens using methods similar to yours... clearly it can work well.

I think so. I've done it in the past with pretty good results. The additional twist is about 3-4 degrees so I reckon it'll be ok.

I did give full throttle to the previous one. It was very stable at high speed.

The only problem I had with that one was that it wasn't easy to slow down for landings as it would become unstable at lower speeds.
That resulted either in hot and bouncy landings which many times ended in a nose over (because of the nose wheel collapsing), or dropping a wing and spiraling down like in the last flight.

What I'm seeking this time is to give it more stability at slower speeds.
I'm also considering the possibility of adding split flaps as in the real one (inner flaps going down, outer flaps going up). I figured out how to do that with a single servo per pair of flaps.

I'm not sure whether flaps will help with stability or not, though...

Originally Posted by mperaltaoz

I think so. I've done it in the past with pretty good results. The additional twist is about 3-4 degrees so I reckon it'll be ok.

I did give full throttle to the previous one. It was very stable at high speed.

The only problem I had with that one was that it wasn't easy to slow down for landings as it would become unstable at lower speeds.
That resulted either in hot and bouncy landings which many times ended in a nose over (because of the nose wheel collapsing), or dropping a wing and spiraling down like in the last flight.

What I'm seeking this time is to give it more stability at slower speeds.
I'm also considering the possibility of adding split flaps as in the real one (inner flaps going down, outer flaps going up). I figured out how to do that with a single servo per pair of flaps.

I'm not sure whether flaps will help with stability or not, though...

I think 'crow braking' as you describe it with the flaps might work, but the main issue you would have would be lateral/roll stability. Have you thought about possibly using the crow braking, but also some sort of spoiler/braking unit that would pop out of the wing? I know full size gliders use spoilers to decay lift, so it occurs to me that if you have spolier AND crow braking, then you should be able to slow down and drop the aircraft in reasonably neatly.

Not sure if it would work...probably something that would need to be built and tested fairly rigorously in order to prove the concept, but hey...

My 2c worth anyway. Would be interested in hearing if anyone has any other ideas...?

Put a big (ish) fin on it ?.
The Hortens were "iffy" designs.. at best.
ALL subsequent post war analysis revealed their designs to be poor..unarguably seductive visually, but ugly Aero contraptions.
Had the war continued, it's likely the Hortens wouldn't have survived the blowback on their designs/claims.
Reimar Horten was one Stereotypically stubborn individual... refusing to clutter his 'design' with vertical Fins .
Of Lippisch stature he demonstrably was Not.
His subsequent aero/wing design work in Argentina ( a cliche in itself was spectacularly poor.. adding genuine credibility to the above.

That is neat I wondered how many other people knew about the Horton.