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Vimana89 Slender Delta Projects and Testing Log

Vimana89

Well-known member
#1
This will basically be a log where I update and share projects and stuff related to my slender delta designs. My V Sliver is a pretty good intro and makes a good easy Ret plane, like a Nutball or Flyer with its own unique handling characteristics thrown in the mix. It gives a good impression of how slender deltas handle in level flight and high alpha, but minus the rolls, so it's not quite the full experience. Many who fly a lot of ailerons and elevons would say somewhat watered down. I like it for what it is, but want to continue my slender delta design into sort of a series, involving higher performance models that really maximize the potential of this planform.

I've been messing around with a couple tailed AET variants, and they have been fun but a bit flawed. I have somewhat of an idea on how to make this design more efficient by extending the length of the tailplane, but I still think it would lose a lot of high alpha capability, and not be as efficient as elevons. The tailed variant is something I will still mess with on the side, but I'm not sure that's the next direction I want to go. I was thinking of first scaling up my simple RET build to test a KFM wing idea I had that joins two pieces of a larger wing(and can be made to leave room for dihedral tips for RET). It can give me an idea if I would enjoy this as a larger plane. From there, I could choose the most efficient size for my needs, and then try a straight up 3ch elevon version.

I want the elevon version to be sort of the base for higher performance experiments as I get better, like stepping up to 4ch, EDF, thrust vectoring, etc. The tailed AET might also be a cool approach, but I'm not yet convinced it would be very efficient, so that's on the backburner until I've tried it with elevons. For the first scaled up version, I will be using the same sized motor(radial 2205), because it's pretty overpowered already on the little park flyer version, and it's the biggest I've got. It should handle a larger, but not ridiculously larger airframe no prob, especially since my design has way more wing than fuselage and a low wing loading.

Any input, suggestions, or ideas welcome! I'll update soon with some progress.
 

Vimana89

Well-known member
#6
My modified KFM worked well enough to join and reinforce a longer wing. This is a 20" span by 40" chord. Testing with RET first for familiarity and stall resistance.
 

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Vimana89

Well-known member
#7
The larger variant flies well, but could potentially use a more scaled up power plant. It cruises well and has plenty of power for regular stuff but no excess for particularly good high alpha or anything. The RET turns are a bit clunky but only until you get the technique down. Lots of Dutch roll at low speeds, looks funky but won't hurt, just throttle up and it goes away. Very stable at moderate to fast cruise. Generally forgiving and easy to fly. Not particularly aerobatic, but pretty much stall proof. A fun cruiser that looks super cool.
 

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Vimana89

Well-known member
#8
Video of "Magnum" V Sliver coming soon, more experiments to follow, including a normal park flyer size elevons variant, and more large builds in the future. EDF is another thing I want to try eventually.
 

Vimana89

Well-known member
#10
With further testing, it flies pretty good. That being said, it has enough elevator to climb very nicely, but not as much punch out as I'd like and nowhere near the high alpha I'd like. Whether it will be a future rebuild of the RET version or one with elevons, I believe I will increase the size of the control surfaces a bit and run it on 4s. I could always get a larger motor too if that's the problem.
 

Vimana89

Well-known member
#11
Going to add some footage of the large V Sliver and the best couple clips of the original V Sliver,which is much more aerobatic. For ease of building and compatibility with my available power plants, I'll be prototyping the first slender delta with elevons using similar dimensions to the smaller V Sliver. Would winglets or negative dihedral tips be best, is my question...anyone care to wager?
 

Vimana89

Well-known member
#12
I'm going to try a "standard" size 30ish inch "V Sliver" with elevons! I think the most practical and super cool looking way, is twin vertical stabilizers right at the wingtips with a big @$$ "spoiler" looking horizontal stabilizer joining them over the top.
 

Vimana89

Well-known member
#13
My only question is would such a horizontal stabilizer mess stuff up if elevons are directly beneath it? maybe a nice single, swept VS with a cruciform or top mounted small horizontal stabilizer would be a safer option.:unsure:
 

Vimana89

Well-known member
#15
So I made some major advancements in research today. I got this build to fly with elevons, for a short time, before crashing it to bits testing different props and batteries. It flew, but it was troublesome to dial in and trim, touchy on the roll axis, not enough elevator authority. The banks, when done right, looked and felt smoother than RET. The turns had a lot more grace and depth, and I could practically knife edge it a bit. Other than that, it still had some similar Dutch roll on turns to the RET version, but it was a lot less stall resistant and needed throttle to turn, whereas the RET one can turn while flying slow and/or high alpha.

If I made everything perfect on the 3ch one with elevons and dialed it in just right, which is much more picky than with RET, and then compared it to the 3ch RET, I gain nicer, smoother turns, greater roll maneuverability, "knife edge" potential. I lose low speed maneuverability and maneuverability in high alpha. What this is suggesting, is that these are possibly two sides to a whole coin; in other words, a well designed and built 4ch slender delta would have the best of both worlds; fast, slow, high alpha, rolls, loops, knife edges, etc. That being said, it would require a high level of skill to build and fly to its full potential. That's a project for quite a bit later down the road.

For 3ch elevons, I may find them more enjoyable if I try them on a flying wing or wider delta, but if I have to chose a 3ch build for the slender delta, I think the RET version actually makes a more novice friendly and well rounded little park flyer. I may continue to experiment with other 3ch elevon and tailed ailerons variants, but my next slender delta build will be a smoother, more perfected version of the larger 42" KFM V Sliver. I may even go a bit bigger. This one will be built to last, and the goal will be to hopefully get it as nimble and slow fly/high alpha capable as the little one.
 

Vimana89

Well-known member
#16
Had a couple pieces of white foam and a lot of scrap in different colors. I figured hey, probably won't try elevons again for a bit and will drop back more to my FTFC20 builds soon, so might as well crank out a large RET V Sliver again, and try to make a few minor improvements. Smaller dihedral tip area but 30 degree angle, should keep her just as steady but more lift and less wing rock.elevator scaled up from 3" which was rather close to the small size plane, to a more appropriate 4". The last larger one I had had a small hole for cooling and got a bit warm under the hood,so I not only gave it the full original scoop, but added two more intakes in front that use the unswept space at the front of the wing.
 

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Vimana89

Well-known member
#18
The new RET plane has the lowest aspect yet, probably the max that's practical, but practical it is! This was worth making those nice intakes and putting in extra effort. I made this build very clean and made sure all the little extra fit and finish stuff was done;hinges reinforced with thin layer of glue, servo arms screwed in(what killed my last one), as little slop as possible without going overboard. This plane maidened great, and it smoother, gentler, and more maneuverable than my last 40"+bling build.
 

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#19
After several crashes and repairs, mostly due to freak accidents like glue heating up and coming loose, I decided to address the lack of power and poor lift on low speeds by upping the diameter of the prop with a new nose, which had to be done anyway. 6x3x2 is all I got and it's underpowered, but boy is she more gentle on low speeds and has more elevator punch out, which is good because of more dip from wing warp due to damage and repairs. I'm going to try ordering a couple 6x3x3 and/or 6x4x3 and see if I can really get this plane to fly good and do some high alpha!
 

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