Flite Test Design Engagement Challenge

[Ryan O.]

I really like that plane! I'm interested in seeing how it flies

My guess would be slow, and not well when the throttle is punched. Luckily I'll be shortening the extension by the next one.

 

[FlyingWithRyan]

It's a 70mm in basically a big sailplane, can't get much more efficient than that

But to make a U2 70mm its gotta have a LARGE span

 

[Ryan O.]

But to make a U2 70mm its gotta have a LARGE span

That's the problem with most RC planes based off millitary jets, especially the older turbojets, like on the Hustler. They have really skinny and long engines, which isn't what you wany for EDFs, so with those types of aircraft I almost always see 12 blade 6s fans to generate as much thrust as possible. It may be worth making a slightly larger than scale fuselage to allow for a larger fan, that way your thrust to weight ratio is better, which is good incase you plan on faster flying, or just to get out a a tricky situation.

 

[FlyingWithRyan]

That's the problem with most RC planes based off millitary jets, especially the older turbojets, like on the Hustler. They have really skinny and long engines, which isn't what you wany for EDFs, so with those types of aircraft I almost always see 12 blade 6s fans to generate as much thrust as possible. It may be worth making a slightly larger than scale fuselage to allow for a larger fan, that way your thrust to weight ratio is better, which is good incase you plan on faster flying, or just to get out a a tricky situation.

Yeah but 6s power density is so much nicer but yes I agree a slightly off scale fuse wouldn’t end the cool factor

 

[Monte.C]

My guess would be slow, and not well when the throttle is punched. Luckily I'll be shortening the extension by the next one.

That's one thing I'm still trying to figure out. Really old vintage models would often be built with the wing high up on that extension/pedestal. I don't remember ever seeing a full-size plane looking like that. The only thing I can think of is that it's for stability. I mean - they started with free-flight models, then an incredibly primitive radio controlled rudder...
The other thing I'm still figuring out is why they often gave the wing a couple degrees upward angle of attack, but it must be something to do with such a high wing, and similar to how we give the thrust axis a bit of downward angle.

 

[FlyingWithRyan]

That's one thing I'm still trying to figure out. Really old vintage models would often be built with the wing high up on that extension/pedestal. I don't remember ever seeing a full-size plane looking like that. The only thing I can think of is that it's for stability. I mean - they started with free-flight models, then an incredibly primitive radio controlled rudder...
The other thing I'm still figuring out is why they often gave the wing a couple degrees upward angle of attack, but it must be something to do with such a high wing, and similar to how we give the thrust axis a bit of downward angle.

1 to quote Cessna, “High wing stability ask any bird”
2 yes a high wing is more stable, fight me on it 😂
3 the positive angle of attack in the wing is so that free flight models would naturally gain altitude with thrust but its a pretty good practice for RC trainer/slow flight models too.

 

[Monte.C]

1 to quote Cessna, “High wing stability ask any bird”
2 yes a high wing is more stable, fight me on it 😂
3 the positive angle of attack in the wing is so that free flight models would naturally gain altitude with thrust but its a pretty good practice for RC trainer/slow flight models too.

Sure, I'm with you 100%.
I'm normally really good at figuring out mechanical/3-dimensional things, but between thrust, thrust angle, airspeed, wing AOA and horiz tailplane AOA and all the combinations and variations it hurts my brain.
It doesn't help that planes are like that anyway - Somebody tries an idea and then it works and then they spend years and a fortune to invent new math to figure out WHY it works. And then they think they know but really they don't. All they've done is create guidelines and tendencies and findings.

 

[Ryan O.]

Let's just say V4 is going to have some changes, and V3 is no longer with us 😉
The plane was a little too stable with roll, and a little unstable in pitch, due to the high mounted wing.

 

[Tench745]

That's one thing I'm still trying to figure out. Really old vintage models would often be built with the wing high up on that extension/pedestal. I don't remember ever seeing a full-size plane looking like that. The only thing I can think of is that it's for stability. I mean - they started with free-flight models, then an incredibly primitive radio controlled rudder...
The other thing I'm still figuring out is why they often gave the wing a couple degrees upward angle of attack, but it must be something to do with such a high wing, and similar to how we give the thrust axis a bit of downward angle.

I mean, wing pylons are a thing that exists on full scale aircraft. As far as models are concerned, a pylon is a way to raise the wing without the drag or complexity of a bunch of tiny struts. Also, it moves the wing away from the fuselage, minimizing interference drag.

 

[Crawford Bros. Aeroplanes]

But to make a U2 70mm its gotta have a LARGE span

That's the problem with most RC planes based off millitary jets, especially the older turbojets, like on the Hustler. They have really skinny and long engines, which isn't what you wany for EDFs, so with those types of aircraft I almost always see 12 blade 6s fans to generate as much thrust as possible. It may be worth making a slightly larger than scale fuselage to allow for a larger fan, that way your thrust to weight ratio is better, which is good incase you plan on faster flying, or just to get out a a tricky situation.

It'll have a 6' wingspan, making the fuselage a solid 3" diameter or so. I did all the math months ago, this is an older project that I'm reviving. I build a lot of gliders in the same size range, my heaviest tops out at 480g and most of that is the battery. At this point I think a larger than scale fuse will just be extra weight without increased wing area, meaning heavier wing loading. A 70mm on 4s shouldn't have any problem keeping this thing up especially since I'm not planning on flying fast, just scale soaring around the park.

I went to build the wings today but it's been over two months since I've worked on a plane so naturally all my tools grew legs and bailed. I managed to get a new razor but my cutting mat was nowhere to be found. I spent almost two hours tearing the house apart looking for it before someone suggested that it might've fallen out behind the drawer it was in, down inside the back of the cabinet. Sure enough that's where it was.

 

[Crawford Bros. Aeroplanes]

Also looking at starting on a PT-19 soon, I found this one from a while back and It's pretty much exactly what I was going to do so I might as well build it right?

https://forum.flitetest.com/index.php?threads/pt-19.22729/

Looks like the 58" version flies really well, I'll probably build the 48" one for logistical reasons. Should be a fun build.

 

[Ryan O.]

Here's a screenshot of the moment the plane impacted the ground, I forgot to include it in the post above, the landing gear took all the impact, so luckily its removable. I guess you could say the plane was only doing a touch n go

 

[danskis]

@Ryan O. - I like the high wing....looks great as a vintage plane and definitely meets the challenge criteria. Very original approach. It would be great if you could make it work. Look great with one of these
https://willynillies.com/shop/ols/products/cox-td-020-motor-mount-for-1306-motors

 

[Ryan O.]

@Ryan O. - I like the high wing....looks great as a vintage plane and definitely meets the challenge criteria. Very original approach. It would be great if you could make it work. Look great with one of these
https://willynillies.com/shop/ols/products/cox-td-020-motor-mount-for-1306-motors

I may 3d print a 2 stroke glow dummy engine, just like the guy who made the original Queen Bee did. Unfortunately the high mounted wing was just a little too stable, so it'll be shortened a little.

 

[mackaiver]

If youre coming to flite fest ‘21 seek us out. Ill give you some of my spare stuff and maybe my friends will follow suit.

sadly i wont be going to flite fest '21, i live in Portland OR. but if your willing to send them my way ill give you my po box.

 

[FlyingWithRyan]

sadly i wont be going to flite fest '21, i live in Portland OR. but if your willing to send them my way ill give you my po box.

Lol

 

[FlyingWithRyan]

I may 3d print a 2 stroke glow dummy engine, just like the guy who made the original Queen Bee did. Unfortunately the high mounted wing was just a little too stable, so it'll be shortened a little.

Orrrrr put a real glow engine on it?

 

[mackaiver]

i could nut it might be a bit cramped on the mini bf 109z i made.
i understand if you don't want to mail it, but i will be at flite fest '24.

 

[The Hangar]

Alrighty guys, the plans are done! As soon as I get my needle cutter up and running I’ll cut out another one and make a build video.

https://forum.flitetest.com/index.php?resources/f7f-tigercat.192/

 

[FlyingWithRyan]

Alrighty guys, the plans are done! As soon as I get my needle cutter up and running I’ll cut out another one and make a build video.

https://forum.flitetest.com/index.php?resources/f7f-tigercat.192/

Kinda surprised this thread is still alive 😂