The Stiletto - a Simple Push-Pull Delta

[Yusernaym]

a set of matching props

the current props are both 6x4 and counter rotate, but the front is an apc and the back is a lighter one that came with my power pack. I would rather have two of the same prop with opposite directions.

 

[Yusernaym]

I've added vent holes in anticipation of the esc's not being happy with no airflow. Online thrust calculators put it at between 3 and 4lbs of static thrust. Though it's likely a little less, it's still a hilarious amount of power for the weight of this plane. I just throttled it all the way up while holding it the first time, and it was very impressive.

 

[flamingo]

you got plans for this

 

[Yusernaym]

you got plans for this

not yet - I'm still very early in development. The current iteration hasn't even flown due to weather. Once I get it stable and consistent, whichever version that is, I'll make plans, but for now I'm going to keep tweaking various aspects.

 

[Yusernaym]

Update: Revision 1 flew, briefly. It's tail heavy, but I have a little room to play with, so I'll see if I can get this version to fly to learn more about what I need to change for the next iteration. Currently, I'm thinking of going back to the equilateral delta wing and extending the fuselage a little bit. It's been challenging to keep the weight down while getting it to balance, so I'll stop trying to fit within the triangle.

 

[Yusernaym]

Here are some stills from the first and only flight of V0.2.

 

[Yusernaym]

It's once again time to ask you all for some help. The next iteration of the Stiletto will have an actual airfoil for the first time, but I'm not sure what profile it should have. I'm thinking about taking the paper off of a separate piece of foamboard and sanding in the right shape for it to act as a spacer to define the airfoil. My only question is what shape of airfoil works best on a delta. Should it be fairly symmetrical, or a bit behind the leading edge, tapering back across the whole wing?

 

[Timmy]

It's once again time to ask you all for some help. The next iteration of the Stiletto will have an actual airfoil for the first time, but I'm not sure what profile it should have. I'm thinking about taking the paper off of a separate piece of foamboard and sanding in the right shape for it to act as a spacer to define the airfoil. My only question is what shape of airfoil works best on a delta. Should it be fairly symmetrical, or a bit behind the leading edge, tapering back across the whole wing?
View attachment 179572

try a stepped KF-2 airfoil.

 

[Yusernaym]

I think that a step would actually be more difficult than a sandwich style airfoil given the structure of the wing, but I appreciate the suggestion.

 

[Yusernaym]

Here's a rough mockup of how much the front electronics will be shifted forward. This finally brings the cg within the calculated range, instead of being tail heavy. I'll just tack on some foam with hot glue and packing tape for now, then integrate the extension into the design for the next iteration. I'll have to extend the xt30 lead for the escs even further, as it was barely long enough already, but aside from that it should be pretty straightforward.

 

[Timmy]

What if you fold the wings like you would the wings of a paper airplane?

 

[Yusernaym]

What if you fold the wings like you would the wings of a paper airplane?

What do you mean by that? That's how I would describe the wings right now. It's one piece, cut into the right shape, with double bevels, then folded over and glued to make it solid.

 

[Timmy]

What do you mean by that? That's how I would describe the wings right now. It's one piece, cut into the right shape, with double bevels, then folded over and glued to make it solid.

 

[Yusernaym]

Update: the nose has been lengthened, and she's looking mean. I feel like the name keeps getting more fitting as the project progresses.

Weight came out a little higher than I expected, but I think getting glue joints right the first time will help the next iteration in that area.

 

[Yusernaym]

She's looking a little different now. I had another unsucessful test flight today. Same kind of thing as the last one, where it was flying level okay until I tried to roll, at which point it started spinning and did a nosedive. I've added more area to the vertical stabilizer in hopes of helping with the twist, which will be tested later today.

The only props my hobby shop had that matched were a set of 6.1x4.5x3 quad props, which turned out to be great. They're cheap, light, look good, and produce way more thrust than the ones I was using. I even put one on the Arrow, which is now considerably faster, though the esc was overheating without any airflow, so I've moved it to the outside.

 

[Yusernaym]

Major update: on today's second try, we got controlled flight for the first time! There are serious stability issues at low speeds, so it did end in another crash, this time into a tree, but I got very lucky and had no damage apart from the vertical stabilizer base pulling off of the fuselage. I'm hoping to have another flight tomorrow to learn more about how it handles as is for improvements to the next iteration. I'm hoping it's a case of it flying well as long as you keep your speed up, but we'll see. it's really exciting to get results out of the prototyping process, and even if it's not flying well, I'm ecstatic that something I came up with is able to fly.

 

[Hondo76251]

Id go for the KF-2 Stepped airfoil style, but angled as if it were a paper airplane...

than I'd throw some landing gear on it and see how she stacks up in our "Bush Plane" Challenge!

I kid, I kid...

But in all seriousness, any plane of this design always ends up being more of a controlled missile than a typical plane. I wouldn't worry too much about the design or shape of the airfoil but rather the control surfaces and how they affect flight as they are applied...

 

[Timmy]

Id go for the KF-2 Stepped airfoil style, but angled as if it were a paper airplane...

than I'd throw some landing gear on it and see how she stacks up in our "Bush Plane" Challenge!

I kid, I kid...

But in all seriousness, any plane of this design always ends up being more of a controlled missile than a typical plane. I wouldn't worry too much about the design or shape of the airfoil but rather the control surfaces and how they affect flight as they are applied...

agreed.

 

[Yusernaym]

Honestly, I'm kind of hesitant to go with the stepped airfoil, as it would require either cutting out half of the upper section of my wing, which is where most of the strength comes from, or tacking on another layer of foam, which adds drag and weight compared to the sandwich design.

 

[Yusernaym]

Finally had the time to go fly again, and my suspicions have been confirmed. This plane flies well when you're going fast, and doesn't fly at all if you're going slow. The next version will have some kind of airfoil for sure to help keep it up, but this one is still a lot of fun. It is terrifying to fly in a very fun way. It's fairly stable at high speeds, but quite twitchy. I'm going to be dialing back my dual rate to get better roll control on future flights. It's pretty sturdy, too. My "landing" which was only a landing and not a crash because the plane can still fly, came after I cut the throttle to try to lose some altitude and bring it in. It did a nosedive immediately, which I tried to power out of, and managed to almost level out before hitting the ground. The front prop was bent, but otherwise it's fine. I wish I had time to work on the next version today, but I have work soon, so it'll have to wait. I'm absolutely going to be making plans for this once I have the next revision sorted. It's a blast to fly, and I feel like if I get the low speed handling to exist, it could be something I would recommend others build.