First attempt at design for electric delta pusher

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Speedboat100

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I wonder what it would take to get the effect of a double delta.

Double Deltas have vastly better handling characteristics.

Saab double Deltas are so maneuverable that they can outperform Russian SU-27s.

There is video of them doing the “cobra” maneuver at high speed and extremely nimbly, greatly exceeding the flanker. Makes the Flanker look like a B-52 in comparison.

Here is the Saab Draken video:
 

RCBinChicken

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May 19, 2019
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What a joy to see, somebody else also working with a pusher, that is like in the middle between a deltawing, a flying wing, and a blended wing body :) I had the same idea, just a 4-seater, in stead of a single searter. I made some very early and preliminary 3D-drawings. (They still need to a lot of details, like air intakes, control surfaces, doors, etc. But already in this unfinished state, I think it looks promising. (and gorgeous)
Your model does look gorgeous! I've built RC aircraft of a similar config and they flew well, although what is desirable in RC doesn't always translate to 1:1 scale so I can't comment on stability etc. :p I'm guessing by the smooth curves that this would be a composites bird?

I wonder what it would take to get the effect of a double delta.
Double Deltas have vastly better handling characteristics.
Saab double Deltas are so maneuverable that they can outperform Russian SU-27s.
There is video of them doing the “cobra” maneuver at high speed and extremely nimbly, greatly exceeding the flanker. Makes the Flanker look like a B-52 in comparison.
Here is the Saab Draken video:
I wish... the Draken is my absolute favourite fighter and strong contender for my favourite aircraft ever, and a substantial part of the reason I love deltas so much. Love that video, have watched it umpteen times but can always go one more. :) But sadly I couldn't figure (yet) a good way to wrap the outward shape of the Draken around the physical constraints of a small, cheap, lightweight homebuilt: the sheer length of the airframe alone presents difficulties with CG (choose your poison: pilot at the front, horribly nose-heavy OR pilot further back, severe visibility issues) and for every bad thing I hear about drag of low-speed, low-aspect-ratio wings, the Draken would be even worse with its ultra-narrow span.

But that said, I hate to give up on something even if (hell, ESPECIALLY if) it's outwardly a bad idea - though I imagine the experienced hands here will wince at that sentiment, and I don't blame them - and although I'm not a big fan of the F-22, I'm impressed with what the Archon SF-1 guys accomplished in a similar vein. So I'll keep plugging away with my sketches, and if things do take a Draken-ward turn one day, I'll be very happy. The thought of seeing THAT shape waiting by a runway and knowing it's mine and I can go fly in it... without needing a few million bucks... it's a heady thought!
 

Johan Fleischer

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Aug 24, 2019
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[QUOTE :p I'm guessing by the smooth curves that this would be a composites bird?
-Yes composites :) I am in the process of moving to another 3D app, in order to get more precise results. It's a steep learning curve, but I will definitely upload new pictures.
 

Bille Floyd

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Sep 26, 2019
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242
...


I highly recommend trying out tandem hang gliding if you have not already. It will give you a very good idea how your aircraft will handle in real life.
Off topic here ; i'll get back On in a moment :

From 1980 to 1990 , i sold Hang glider 'Rides" for a living
over the cliffs of Torrey Pines , norh of San Diego ; was a
LOT of Fun, (but didn't do Squat , for my work ethic) !!
Sold about 3500 rides .

On your delta wing :
I highly recommend you build a scale model , and fly it
RC first ; make it a BIG model , or the Reynolds numbers
will be so different, that Ya won't get good data to scale
it up.

Bille
 

pictsidhe

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Unfortunately, an electric Draken won't work with current technology. It would be a huge challenge with a conventional engine. Have a look at Malish's PJ-II Dreamer in the ducted fan thread for the best example yet of how to build a pseudo-jet while using a reasonable AR and getting decent performance.
I'd love an English Electric Lightning. But, it just won't work as a homebuilt. I'm 'making do' with a WWII fighter, instead.
 

Johan Fleischer

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Aug 24, 2019
Messages
25
Your model does look gorgeous! I've built RC aircraft of a similar config and they flew well, although what is desirable in RC doesn't always translate to 1:1 scale so I can't comment on stability etc. :p I'm guessing by the smooth curves that this would be a composites bird?




I wish... the Draken is my absolute favourite fighter and strong contender for my favourite aircraft ever, and a substantial part of the reason I love deltas so much. Love that video, have watched it umpteen times but can always go one more. :) But sadly I couldn't figure (yet) a good way to wrap the outward shape of the Draken around the physical constraints of a small, cheap, lightweight homebuilt: the sheer length of the airframe alone presents difficulties with CG (choose your poison: pilot at the front, horribly nose-heavy OR pilot further back, severe visibility issues) and for every bad thing I hear about drag of low-speed, low-aspect-ratio wings, the Draken would be even worse with its ultra-narrow span.

But that said, I hate to give up on something even if (hell, ESPECIALLY if) it's outwardly a bad idea - though I imagine the experienced hands here will wince at that sentiment, and I don't blame them - and although I'm not a big fan of the F-22, I'm impressed with what the Archon SF-1 guys accomplished in a similar vein. So I'll keep plugging away with my sketches, and if things do take a Draken-ward turn one day, I'll be very happy. The thought of seeing THAT shape waiting by a runway and knowing it's mine and I can go fly in it... without needing a few million bucks... it's a heady thought!
 

henryk

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This is a (scruffy) 3D model of my ideas so far..









What a joy to see, somebody else also working with a pusher, that is like in the middle between a deltawing, a flying wing, and a blended wing body :) I had the same idea, just a 4-seater, in stead of a single searter. I made some very early and preliminary 3D-drawings. (They still need to a lot of details, like air intakes, control surfaces, doors, etc. But already in this unfinished state, I think it looks promising. (and gorgeous)
=clean,good plane !

=iff instal LE VORTEX GENERATORS (Kasper mode),
(the same as BOING X-32A have),you can fly very slow
at take off and landing phases with low AoA !

 

Speedboat100

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Slow progress, but here are some noe pictures. I've added fins and ailerons, door, doorhandle, landing gear, exhaust pipes, etc. And I also have some comparisons with Cirrus SR22, so you can see, it's within the size of a "normal" 4-seat aircraft

Most awesome...keep up the good work !
 

Riggerrob

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Pretty drawings Johann!
May I make a couple of suggestions about fences and seats?
First, wing fences can prevent deep stalls.
Saab Draken and Velocity kitplane all suffer from deep stalls where the outer wing panels are stalled, but onboard leading edges still develop vortex lift, ergo no nose-down pitching moment when stalled. Part of the problem was that better wings start to stall at the root, then the stalled area slowly expands outboard. This sort of progressive stall helps maintain aileron/roll control part way into the stall. This works great until the outboard wing panels are swept too far aft and you lose nose-down pitching moments.
Wing fences can help prevent the stall from moving outboard too fast. Mig 17 and 19 jet fighters have huge wing fences. Later jet fighters have dog teeth or longitudinal slots that create vortexes that “cut” spanwise flow. Rutan solved his deep-stall problems by installing mini-pylons on the undersides of his swept wings. Rutan’s mini-pylons sort of resemble the engine pylons installed on most airliners.

My second suggestion is about seating. Keep the pilot’s seat near the nose for the best visibility, but wait until you have done a few weight and balance iterations before nailing passengers seats in. To simplify w & b, try to install passenger seats close to the centre of gravity. Hint: look at seating in Dyke Delta.
 

Johan Fleischer

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Aug 24, 2019
Messages
25
Pretty drawings Johann!
May I make a couple of suggestions about fences and seats?

My second suggestion is about seating. .
Thank you so much for your advice, Riggerrob. I'm only a graphic artist with much interest in aircraft, and i'm honoured, that my unqualified artwork has some interest among people with real knowledge. I have no idea, if my design could fly in real life. As now, just regard it as eye-candy. But I would be very honoured, if it evokes enough interest, so that somebody with more knowledge and skills take the idea and develop it from "unqualified daydream" to a dream, that maybe COULD fly. But I guess, that needs not only skills / knowledge, but also research/testing, since my design is a weird hybrid between deltawings and Blended-wing-Body and flying wings. So, those very fat strakes/wingroots, do they have same stall characteristics as thin wing delta's (or normal wings Velocity?) How are stall characteristics in BWB? How are they in Dyke Delta (or Verhees Delta D1 and D2?)
Henryk suggested to have leading edge vortex generators, (flaps) as seen on Kasperwing and Boeing x32 (both Kasper and Boeing have patented the idea) Those could also mitigate stall-problems, I guess.
I also appreciate your advice to move the pilot more front, and keep passengers near CG. I would also love to have the access door more in front and free of the thick wing leading edge.But first I need to know the engine's weight and position. Right now, I have some problems positioning the engine, so i doesn't collide with the retracted landing gear.
Lots of things to be sorted out, if my design should go from "eyecandy" to "qualified dream". So I'm very thankful for all ideas from everyone. My intention was only to make a clean design, "slick-as-a-fish".

I think I will move further posts to another thread. This one is about RCBinChicken's electric one-seat pusher, and I will not drag attantion away from his project. I think there's a thread here in HBA named "My crazy idea" or something. I really belong there more than here :)

As I move from this thread, I will just post another illustration (with a background picture), where you can really appeciate it's almost salmon-like test-5.jpg clean fuselage. And another one, with a person standing nearby, so you can compare size with a person. In the last picture, the fuselage "spine" reminds me a little of the front end of B1 Bomber, haha.

Screen Shot 2019-11-23 at 00.19.16.jpg
 

b7gwap

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UT
Cool sketch, RCB!

I think you and some of the tailless guys here are having good and productive discussions.

Returning to construction methods, let’s take a look at your benchmark, the Sandlin Bloop(s). Mike uses traditional tube ladder with external bracing wires to get the stiffness and strength he needs. The Bloop is not un-Wright Flyer-like and has a flight envelope to match.

The comely Delta you’ve sketched out will need to have a cantilevered wing. Someone correctly mentioned that the combination of short span with very thick airfoils will aid you in that, since less spar material will be needed than for a conventional wing, but the design elements are very different when going from external wire bracing to cantilevered anything.

For an example of this, compare the Skypup’s wing to the Bloop’s. You’ll need to design the spar around the gross weight of the aircraft at some limit load you think is reasonable, then choose materials and thicknesses/taper ratios. It’s structurally elegant and efficient, but it’s not as TLAR as wire bracing tubes together, ergo a LOT of design work to get confident. Not to say don’t do it. It would be valuable even if the napkin gets crumpled and discarded at the end.
 

bmcj

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I say since you are powered electric, take advantage of the relatively light weight of the motor and either extend the motor mount or trim away any surfaces right in front of the prop so that you have relatively clean air entering the prop disc instead of running it in the wake of a nearby surface.
 

henryk

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I say since you are powered electric, take advantage of the relatively light weight of the motor and either extend the motor mount or trim away any surfaces right in front of the prop so that you have relatively clean air entering the prop disc instead of running it in the wake of a nearby surface.
=the propeller after traling age is relatively noisy !
 
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