Lakeroadster's Flutter-By Upscale

[lakeroadster]

Here's an upscale version of the Estes Flutter-By 18mm powered flutter recovery LP rocket. The Estes rocket is basically a 2FNC fuselage and a 2F MM that separate at motor ejection. A truly genius design... well, IMO anyways.

This upscale has 29mm power capabilities and has a BT-60 main body tube. It's arguably best flown on 24mm motors to ensure recovery.

 

[BABAR]

Should work great, especially on a grass field.

my opinion (Speaking from experience.)

first, with no streamer and no chute, this great rocket is nonetheless a PITB to track AND find on the ground, especially with two sections to keep track of. You need two spotters, and at ejection designate who is tracking which part (such as, “I’ll take the right piece and you take the left”, otherwise 50 percent chance you are both tracking the SAME part.)

fly this on a relatively flat grass field, even upsized, the parts can disappear in tall grass or bushes of nearly any size.

use the LOWEST impulse motor possible that keeps the stack EASILY in visual range (depending on your Eyes, I’d say 300 feet MAX.). This rocket’s cool factor is in the easy prep and the recovery technique, you get nothing but grief flying it out of site. to me, a flight of 300 feet really isn’t much more exciting than a flight to 50 feet with this one.

Hard to predict where the sun is going to be (or more correctly, where the ROCKET is gonna be in regards to sun) but best flown before 10 or after 2 to decrease risk of losing site of parts in the sun.

color it very vibrant and contrasty relative to the landing site. Decals, shmecals, this is all about recovery and little to do with looks. I flew my first unpainted in fall with lots of leaves on the ground, and balsa and cardboard don’t stand out well in that environment. Let’s just say I recovered the nose cone half, which was good, as the other half was easy to remake from spare parts. I’d also say don’t put extreme effort into finish work, as this rocket likely ranks close to the standard Mosquito in “easy to lose” statistics.

matter of opinion, but I think this is one of the few rockets that really looks GOOD with perfectly flat unfoiled fins. Yeah, it’s gonna cost you in drag, but who care? You don‘t WANT altitude anyway. You can paper the fins (good for finish and strength) very easily with flat edge fins.

this is also a bird that may benefit from balsa fillets or other things to strength the joint especially on this long forward section fins, they take a beating on landing due to rotational energy disappation.

Light winds and straight trails!

 

[lakeroadster]

Should work great, especially on a grass field.

my opinion (Speaking from experience.)

first, with no streamer and no chute, this great rocket is nonetheless a PITB to track AND find on the ground, especially with two sections to keep track of. You need two spotters, and at ejection designate who is tracking which part (such as, “I’ll take the right piece and you take the left”, otherwise 50 percent chance you are both tracking the SAME part.)

fly this on a relatively flat grass field, even upsized, the parts can disappear in tall grass or bushes of nearly any size.

use the LOWEST impulse motor possible that keeps the stack EASILY in visual range (depending on your Eyes, I’d say 300 feet MAX.). This rocket’s cool factor is in the easy prep and the recovery technique, you get nothing but grief flying it out of site. to me, a flight of 300 feet really isn’t much more exciting than a flight to 50 feet with this one.

Hard to predict where the sun is going to be (or more correctly, where the ROCKET is gonna be in regards to sun) but best flown before 10 or after 2 to decrease risk of losing site of parts in the sun.

color it very vibrant and contrasty relative to the landing site. Decals, shmecals, this is all about recovery and little to do with looks. I flew my first unpainted in fall with lots of leaves on the ground, and balsa and cardboard don’t stand out well in that environment. Let’s just say I recovered the nose cone half, which was good, as the other half was easy to remake from spare parts. I’d also say don’t put extreme effort into finish work, as this rocket likely ranks close to the standard Mosquito in “easy to lose” statistics.

matter of opinion, but I think this is one of the few rockets that really looks GOOD with perfectly flat unfoiled fins. Yeah, it’s gonna cost you in drag, but who care? You don‘t WANT altitude anyway. You can paper the fins (good for finish and strength) very easily with flat edge fins.

this is also a bird that may benefit from balsa fillets or other things to strength the joint especially on this long forward section fins, they take a beating on landing due to rotational energy disappation.

Light winds and straight trails!

Lots of great advice, thank you for taking the time to write this.

I revised the design to use my balsa ply fin technique. This is lighter than basswood. In addition, I dropped the nose ballast down for a D12.

Also revised the color scheme to DOT approved high visibility colors. One thing to keep in mind... since this is an upscale the parts are bigger, should be easier to find the parts.

 

[BABAR]

i am not I impressed by the rail speed on any of those motors, although the altitudes for anything over a D are eye popping.

300 feet is more than enough altitude for this rocket‘s unique recovery profile,

 

[lakeroadster]

i am not I impressed by the rail speed on any of those motors, although the altitudes for anything over a D are eye popping.

300 feet is more than enough altitude for this rocket‘s unique recovery profile,

My Ahpla simulated at a 25.5 mph rod clearance speed. Since this rockets cg is so close to the fins I don't anticipate much weather cocking.

 

[BDB]

I've always been fascinated by maple seed recovery. I still occasionally fly an Estes Tornado from the '90's. I can't believe I haven't lost it yet.

I have kicked around the idea of designing some larger models that employ it. An upscale Tornado would be great, but it would be cool to design something de novo. Do you know if there are any design principles for maple seed recovery?

 

[lakeroadster]

I've always been fascinated by maple seed recovery. I still occasionally fly an Estes Tornado from the '90's. I can't believe I haven't lost it yet.

I have kicked around the idea of designing some larger models that employ it. An upscale Tornado would be great, but it would be cool to design something de novo. Do you know if there are any design principles for maple seed recovery?

Other than the components must be unstable, once the rocket disassembles?

 

[BDB]

Do both "halves" of the Flutter-By simply tumble? I thought one of them might have "helicoptered" like a maple seed. That's what the upper portion of the Estes Tornado does, and that's what I'm interested in designing.

 

[BABAR]

Other than the components must be unstable, once the rocket disassembles?View attachment 535029View attachment 535030

I think @lakeroadster is on to something, but one other factor, I think the fins in the pieces must be uni-planar or near so. Such is not the case for typical low power booster tumble recovery, which seems to tumble pretty much randomly. The tumbling creates drag, sure, but the drag surface area is constantly changing, so while it is certainly greater than ballistic recovery (ballistic recovery is sort of the “anti-ideal”, aka “worst possible case”), it is different from the “optimal” no chute or streamer horizontal recoveries of @Dotini ‘s Horizontal Spin Recovery (with posssssssssible assistance of Magnus Force, although latter proven to be present but not proven to be beneficial in slowing descent rate) or the Alway Bros (Back Slide). A stiff* unstable uni-planar object with an eccentric CG** i theorize would spontaneously spin either in a flat orientation or maybe slightly cone shaped presenting maximum or near maximum surface area to the relative vertical airflow generated by gravity/fall trajectory. Aside from @Flyfalcons spectacularly successful and ingenious guitar rocket
https://www.rocketryforum.com/threads/summer-buildoff-roc-n-roll-flying-v-guitar.134436/
I think there are few if any rockets with two planar fin attached orthogonally to the body tube.

hence both the maple seed rocket and FlutterBye separate into two part (I think one part of the Maple Seed has two fins no exactly uniplanar, but enough “off” to create a spin. You might consider these rockets “stablely unstable”, they don’t go ballistic but they DO Go into a controlled flat or cone shaped spin.

*stiff: I am thinking that you need to exclude a piece of paper, as it is constantly changing shape.

**eccentric CG: a flat circle or square of cardboard might not spin because there is no weight on one edge to pull it slightly down, i think you need a bit of eccentricity to get the airflow a bit off axis to get a spin.

doubting Thomas that I am, I am not convinced that EITHER the Maple Seed nor the FlutterBye are true helicopters, in the sense that I don’t think their spin creates significant LIFT. perhaps @prfesser , @georgegassaway , @Rktman , or others “in the know” can correct me, but I think both the above and likely many if no most of my flat bladed “helicopter” designs (which are all flat blades, I.e. no true airfoil) produce most of not all of their recovery effect (slowing the descent to a safe velocity) predominantly by creating a high drag configuration rather than by generating true lift. From my personally and very unscientific documentation of my own rockets, my Air Brake recovery rockets which are designed intentionally to PREVENT spin with no blade angling (they often lazily spin anyway, certainly not enough to generate lift) and my nearly identical helicopter rockets which had around a 5 degree blade angle TO generate spin seem to descend at about the same rate, so I think it’s mainly drag that slows both. Four blades, each 18 inches long and 1 to 1.5 inches wide, plus four fins each about 2x2 inches, make up about 88-123 square inches of surface area, about the same as a 16-25 inch parachute if my math is right. My scientific knowledge is insufficient to compare the efficiencies of a fixed surface area of flat blades vs the same fixed area of a parachute or more commonly parasheet.

Turning almost any rocket sideways creates a good bit of drag, which for long lightweight low power rockets can significantly retard the descent velocity. Remember, the length of the body tube is largely ignored in terms of Drag/CP calculations by Barrowman and most Sim calculations due to assumption that rocket is at near zero angle of attack in boost phase. in

combination with fins and nose cone oriented sideways (a big drag element, especially fins) it is challenging to get a rocket to go very fast SIDEWAYS.

 

[neil_w]

This isn't mapleseed recovery, it's just a form of tumble recovery. Which is cool enough on its own (for a design like this), but a totally different thing. Unless I'm missing something here.

 

[georgegassaway]

doubting Thomas that I am, I am not convinced that EITHER the Maple Seed nor the FlutterBye are true helicopters, in the sense that I don’t thin their spin creates significant LIFT. perhaps @prfesser , @georgegassaway , @Rktman , or others “in the know” can correct me, but I think both the above and likely many if no most of my flat bladed “helicopter” designs (which are all flat blades, I.e. no true airfoil) produce most of not all of their recovery effect (slowing the descent to a safe velocity) predominantly by creating a high drag configuration rather than by generating true lift.

A flat plate or super-airfoiled wing/blade produce just "drag" if they are at 90 degrees to the airflow (no rotation, 90 degree angle of attack). With rotation, then the resulting angle of attack causes SOME lift to occur (even though it is "Stalled"), the flat plate having less lift than the airfoiled blade/fin/wing. With faster rotation, less of an angle of attack, then more lift and less drag. With enough rotation, and a low enough angle of attack, it is no longer stalled and produces a lot more lift. Even a flat plate..... but less lift of course than a crude airfoil, which has less lift than a good airfoil.

The classic old "Flat Cat" glider was designed to not have an airfoil, flat plate, and it glided. But it had inconsistent pitch trim problems as a result, simple rounding of the edges helped to cure some of that (also, it was a zero-incidence design, the fix was to add a hair of up elevator trim to it). Of course, giving it a proper airfoil made it fly better.

Back to copters:
If rotation is fast enough to not be able to see individual blades, more like a blur, then there probably is a lot more lift going on than there is drag.

 

[BDB]

I had no idea this was such an interesting kit. I remember when Estes was practically giving them away. I may need to find one now that they are OOP.

 

[lakeroadster]

This isn't mapleseed recovery, it's just a form of tumble recovery. Which is cool enough on its own (for a design like this), but a totally different thing. Unless I'm missing something here.

Nope, you're spot on, as usually. If it doesn't do a helicopter style spin, it's just flutter recovery.

I just added the maple leaf decals... simply because it looks cool.