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Max, oh you meant the orig BumbleBee. Well if it does not use the turbulence effect, it should not fly at all. Yet thousands did and do. I can't explain. I did not intentionally put it in my bird, the assy was just easier doing it that way. I thought the effect was helping when I ran into it, not really sure. But one thing is for sure, neither the Rumble or Bumble Bee's have had glide stability problems or death dives, when the cg is in the right place. That speaks for itself. Some designs are just good I guess.

James: tell the FAI to allow either RG or BG any glider event. I made plenty of RG's, swingwing, moving this or that, and just got tired of them. I want best performance. Stripping off the motor at least, and maybe a pod, gets that weight off for better glide, and the CG shift is useful for boost to glide trim change. Just my 2 cents. Don't plan on trying out for the Team, just too far to go usually, and costly. Plus as I got older, I hate travel more and more. Especially on those FLYING METAL COFFINS. They don't even give you a chute. I want an ejection seat! :cool:
 
I'm going to gently push back on this statement. I've been close to the center of the FAI whirlwind for almost two decades now, and I can even see my fingerprints on a couple of individual rules. With the exception of the elimination of RC from the S4 event back following the 2000 championships, the Internats community and CIAM never move quickly on a major rule change.

James, I understand that, but all of these have been major transformations of an individual competition class. I don't know anywhere else in FAI flying that we make changes that extreme these days, except maybe F1D in 2000 when they completely scrapped the rules and rewrote them (to massive pushback, mind you).

I can understand implementing changes to the allowance of pod designs or number of R/C channels, but saying we're going from boost glider to rocket glider or no minimum weight to lots of minimum weight isn't so good. Same as this piston launch stuff they're floating.

Again, not necessarily a criticism other than the fact that there needs to be a major community wide discussion before making big changes like these. Just my opinion as someone with a financial interest (conflict thereof?) in the game.

-Josh
 
I made plenty of RG's, swingwing, moving this or that, and just got tired of them. I want best performance. Stripping off the motor at least, and maybe a pod, gets that weight off for better glide, and the CG shift is useful for boost to glide trim change.

Love me some swing wings. Laser beam launch track and they glide really nicely. And they're reliable. Personally I think they're the ultimate planform. The swingflops never really have inspired me.
 
I had a small light A eng swingwing back in the day that won a regional meet! They had 3 glider events, I took them all.

Inspired by the Groundhog, which you may not have heard of, it had unreliable opening. So I made a small bent aluminum plate that the wings were screwed to with alum hdwe, 1/32 ply strips on the root edge reinforced. The plate was lashed to the boom with thread and epoxy, inspired by how they mount stuff on fishing rods.

Eyelets on the boom accepted strings at the front of the wing root. Then a ply "vector director" reversed the direction of the strings towards the tail, where a big rubber band was located. It had plenty of force to open. Burning thread to release wings, worked every time. A3-2T mostly.

I flew flop wings, very popular back in the day, those swinging flop things scare me, way too complex.

Of course others had moving wing or pod, etc.

A friend just uses a pop up elevator with a burn thread, works if everything just right.

Like I say, I only fly BG these days, I am trying to get some high altitude birds with RC to work.

I just completed a RumbleBee-C with an old school model plane type balsa fuse, radio is enclosed within,
sorry, still rudder only. :shock: If it works, if it ever gets warm, will post some pics.
 
Inspired by the Groundhog, which you may not have heard of, it had unreliable opening.

Quite familiar. It's overweight, draggy, unreliable, and generally the reason people think swing wings aren't competitive. I've built the switchblade all the way down to 1/8A (about 1.5g without motor and flies better than most 1/8A pop pod gliders) and it does all the things those old swing wings wish they could do. I also eliminated the burn string nonsense. Just another thing to go wrong. Either a tethered nosecone or a release pin on a sliding nose. Very reliable, no parts to replace after every flight, and just as light.

Swingflop is surprisingly reliable, just not elegant or optimal.

Bill Henderson's Hot Turkey was the ultimate classic swing wing. Big, light, clean, reliable. Other than the burn string. I'm working on an R/C version (without the burn string). Maiden was on an A8-3 and it went up so fast I was dealing with tail flutter. Flew fine though. Once I get that fixed will up the power. It has too much elevator travel anyway, so there are some pretty easy fixes available.

How about photos of your new model?
 
Don't want to show pics until it has flown. No need to display a failure.

I did see a vid of the A10 switchblade take off. Was FAST. You seem to have improved mechanics.

Most people don't have the patience for complication like that, but I admire it. Keep it up.
 
Finally got to do some test flying of my RBC with an old school model plane fuselage. With some unexpected results. As usual. Here's some pics:

IMGP0366.JPGIMGP0367.JPGIMGP0368.JPGIMGP0376.JPG

The first problem, is that with the standard 2.5 degree down tilt on the Vector Pod, it had a bad pitch down moment on boost (B4-2). Not enough to wipeout, but close.

I tried 4 degrees, and now boosts straight up. But that big angle causes the top of the fuselage, aft of the wing, to sort of

BURN.

Oops. Installed some very thin aluminum sheet to protect, works ok. Aluminum foil did not quite cut it.

I don't suggest duplicating this design at this time. If you want to fly a RumbleBee, use the previous design.
Note it is very important to have the CG at the specified location to permit proper transition and glide. It is quite
sensitive to CG being too far forward, if so, you CAN get a death dive.

I am working on a new BG design that has the motor EXACTLY at the thrust CG of the model. Sticking with the

ejectable motor unit, it is very reliable, and can provide enough CG shift to effect glide trim, with careful design.

If anyone is interested, will describe. Also interested in your ideas to accomplish this!
 
Finally got to do some test flying of my RBC with an old school model plane fuselage. With some unexpected results. As usual. Here's some pics:

View attachment 344033View attachment 344034View attachment 344035View attachment 344036

The first problem, is that with the standard 2.5 degree down tilt on the Vector Pod, it had a bad pitch down moment on boost (B4-2). Not enough to wipeout, but close.

I tried 4 degrees, and now boosts straight up. But that big angle causes the top of the fuselage, aft of the wing, to sort of

BURN.

Oops. Installed some very thin aluminum sheet to protect, works ok. Aluminum foil did not quite cut it.

I don't suggest duplicating this design at this time. If you want to fly a RumbleBee, use the previous design.
Note it is very important to have the CG at the specified location to permit proper transition and glide. It is quite
sensitive to CG being too far forward, if so, you CAN get a death dive.

I am working on a new BG design that has the motor EXACTLY at the thrust CG of the model. Sticking with the

ejectable motor unit, it is very reliable, and can provide enough CG shift to effect glide trim, with careful design.

If anyone is interested, will describe. Also interested in your ideas to accomplish this!


One thing I still don't fully understand about the down tilt on the engine pod: wouldn't it cause more looping (pitch up)? The only way I've understood the aerodynamics of the launch situation is to imagine a glider sitting on a fulcrum (e.g. glider balancer) right at its CG, like a seesaw. OK so the engine causes a pitch down moment due to its offset thrust line but the wings create lift (pitch up) in the opposite direction, for the most part balancing each other out.


So wouldn't offsetting the engine pod so its nose (and thrust line) is "up" (toward the top of the glider) only add to the lift of the wings and unbalance things? That's like pushing up on the nose end of the seesaw. Guess the exact situation isn't such an intuitive thing for me.
 
The tilted engine compensates for the down moment of the pod, which is NOT at the centerline of the glider.

It is an old trick, used in Europe often. Note that you don't need it on BG's with a big, long pod, they have plenty of
boost stability. But on RG's and BG's like this one, that use a slight CG shift from the engine module blowing out to
set glide CG, it works with careful design.

I have flown many birds with the Vector Pod, sometimes with a variable setting. When you have it just right, it will
boost straight. Not well known in the USA, it is not for everyone, but it works.

The original RBC works fine with 2.5 deg of tilt. Try building one for free-flight and launch it. With C power, it goes high
and is easy to lose, be forwarned.
 
The tilted engine compensates for the down moment of the pod, which is NOT at the centerline of the glider.

It is an old trick, used in Europe often. Note that you don't need it on BG's with a big, long pod, they have plenty of
boost stability. But on RG's and BG's like this one, that use a slight CG shift from the engine module blowing out to
set glide CG, it works with careful design.

I have flown many birds with the Vector Pod, sometimes with a variable setting. When you have it just right, it will
boost straight. Not well known in the USA, it is not for everyone, but it works.

The original RBC works fine with 2.5 deg of tilt. Try building one for free-flight and launch it. With C power, it goes high
and is easy to lose, be forwarned.


Thanks I think I understand now. The 2.5° "up" angle reduces the amount of pitch down because now its thrust line has changed from what it would be if it were level (it's now angled "up" relative to the front/top of the glider). Would that be correct?
 
Yes. If you studied vectors in high school math, that applies. Again, "normal" BG with a heavy, long pod, the down moment is not noticed because you have the CG so forward, greater stability. Gliders like this don't have the boost CG so forward, it would loop down without the tilt. But the angle has to be exact, a half a degree can affect it, the goal is straight up.

I got away from pop pods because they just don't always work. Fall off too early, don't fall off, get Red Barons. The tech has not changed in 50 years. Some have made novel "high reliable" designs, that tilt off, or use mechanism to force release, etc, but they are generally more complex and heavier.

It is true that if you have elevator control (RBC is rudder only for simplicity), one could set some UP ELEVATOR for boost, and use a normal "parallel" pod, and it will then boost straight. But the angle is critical, and you have to be fast enough to adjust it in real time during boost. E class FAI RG's are usually like this, demanding good pilot skill. I am aiming this design at the low end, beginners, and basic fliers. It flies itself up, transitions, you just steer it with the rudder. You are free to add an elevator to the RBC if you want. It IS useful in higher winds, to adjust glide, but be careful during boost.

I first saw this trick used on an A RG at NARAM 13. Most flew small moving engine, moving wing, flop wing, autoelevator trip, or swingwing. But one guy showed up with big HLG (Hand Launched Glider), with the tiny A3-2 mini-engine on a tilted pod. Looked impossible. It boosted about 100 feet, and perfectly transitioned into a slow, lazy, circling glide, and won the event.

HLG is interesting, they toss them not straight up, but at about 30 degrees from vertical. Fine trim is in place to cause a spiraling ascent in one direction, then it transitions into a circling glide in the opposite direction. They have very good airfoils, and this one had about 10 hand polished coats of lacquer, a nice bird.

When the original Bumble Bee came out, the basis of the RBC (4 times bigger), I tried something wild. The 1/2A glider, about the size of your hand, was fit with a D12 pod! Crazy. It was mounted mid-wing, with an estimated tilt, and some side tilt to make it spin. I fully expected to loop into the ground. But when launched, it did a tight spiral climb to about 800-1000 feet, blew the motor, and went into a nice circling glide! I was flabbergasted. Mainly because I knew I could never get it back. Landed in the next county. Many will not believe this story, but I assure it is true.
 
Yes. If you studied vectors in high school math, that applies. Again, "normal" BG with a heavy, long pod, the down moment is not noticed because you have the CG so forward, greater stability. Gliders like this don't have the boost CG so forward, it would loop down without the tilt. But the angle has to be exact, a half a degree can affect it, the goal is straight up.

I got away from pop pods because they just don't always work. Fall off too early, don't fall off, get Red Barons. The tech has not changed in 50 years. Some have made novel "high reliable" designs, that tilt off, or use mechanism to force release, etc, but they are generally more complex and heavier.

It is true that if you have elevator control (RBC is rudder only for simplicity), one could set some UP ELEVATOR for boost, and use a normal "parallel" pod, and it will then boost straight. But the angle is critical, and you have to be fast enough to adjust it in real time during boost. E class FAI RG's are usually like this, demanding good pilot skill. I am aiming this design at the low end, beginners, and basic fliers. It flies itself up, transitions, you just steer it with the rudder. You are free to add an elevator to the RBC if you want. It IS useful in higher winds, to adjust glide, but be careful during boost.

I first saw this trick used on an A RG at NARAM 13. Most flew small moving engine, moving wing, flop wing, autoelevator trip, or swingwing. But one guy showed up with big HLG (Hand Launched Glider), with the tiny A3-2 mini-engine on a tilted pod. Looked impossible. It boosted about 100 feet, and perfectly transitioned into a slow, lazy, circling glide, and won the event.

HLG is interesting, they toss them not straight up, but at about 30 degrees from vertical. Fine trim is in place to cause a spiraling ascent in one direction, then it transitions into a circling glide in the opposite direction. They have very good airfoils, and this one had about 10 hand polished coats of lacquer, a nice bird.

When the original Bumble Bee came out, the basis of the RBC (4 times bigger), I tried something wild. The 1/2A glider, about the size of your hand, was fit with a D12 pod! Crazy. It was mounted mid-wing, with an estimated tilt, and some side tilt to make it spin. I fully expected to loop into the ground. But when launched, it did a tight spiral climb to about 800-1000 feet, blew the motor, and went into a nice circling glide! I was flabbergasted. Mainly because I knew I could never get it back. Landed in the next county. Many will not believe this story, but I assure it is true.


That's pretty wild. But no one ever learns anything new by not pushing the envelope. I've had my share of experimental failures but I've also an equal amount of unlikely successes. It's been the fastest way up the learning curve and also a lot of fun in the process.
 
That's what makes it Rocket Science!

My favorite is the first Apollo Saturn V flight. Normally would just test unmanned, but decided to rush things and

fly 3 guys around the moon. Fortunately it worked. Note the Russians were quite angry when we beat them to the moon. :cool:
 
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