Estes- New A Helicopter Model just Announced
 

This was a fun model to design.


https://www.estesrockets.com/coming...2-mini-a-helitm




John Boren

John, that is cool! Give Apogee some competition there. When will these be available?

March.

:eek: :cool: Definitely on my list. The dark art of helicopter recovery has always been shrouded in mystery for me. Then again, so has the dark art of hitting the bowl, yet I persist.

John,

Very cool!

If you're allowed, could you post some pictures of the hub. Are the blades set at a fixed angle?

Also, why was this fun to design?

Steve

It looks like the hinge/hub is made from laser cut fiberboard - you can the parts in the photo on Estes website. Along with what appears to be a jig for setting the blade angles and...a tube cutting guide? The yellow gizmo in the center of the parts collection photo looks like one...

The blades are glued to the fiber hinge at a 90 degree angle. You set the blade pitch or what ever you wish to call it with a set of three jigs.


Attached is an image of the blade jigs in use and a close up of the hub.




Helicopter and Glide recovery models are my two favorite types of models.


John Boren

Thank you for coming out with this FAI-type heli-roc kit, John! This configuration is also popular in Europe (and in FAI-CIAM spacemodeling competition countries elsewhere in the world), and it might even become the "Renger Sky Slash of the heli-roc field," in its total impulse category.

Does this use a burn string to retain the blades for launch? The diagram Mr. Boren posted appears to show some kind of sleeve that I assume would slide upwards when the recovery charge goes off which implies a catch of some kind to hold the rotors down. Either way I’m intrigued - should be a fun build and a fun flyer.

That's a good question (that I hadn't thought of, and to which I don't have an anaswer), but... If the kit does utilize a burn string, maybe we can look forward to future Estes boost-glider (B/G) kits (similar to the original-design Renger Sky Slash, which had pop-up elevators) and/or rocket glider (RG) kits that use burn string-retained sliding wings or motor pods, and:

With today's laser-cut sheet balsa (and laser-cut basswood, fiber [beveridge board], and even thin modeling plywood sheet parts), and molded plastic "fulcrum" or interface parts such as rotor hubs, hinges, and motor pod lug/hooks, it is now possible to produce helicopter, B/G, and RG kits that are relatively easy to build and reliable to operate, compared with such kits of a generation ago. Back then, many of these parts had to be cut, shaped, and size-matched by the builder, which made the models tricky to build and more likely to fail in flight. One early (1973) step in the direction of today's kits was Centuri's Hummingbird boost-glider (see: http://www.ninfinger.org/rockets/no...a/73cen70e.html ), which had all-die-cut fiber wings and tail surfaces.

Do you really prep for flight by routing the rubber bands inside the hinge? That's a pinch point. I'd keep the bands out of the hinge mechanism. Putting the bands inside the hinge "ears" could lead to a no-deploy. I'd route the bands around the outside of the hinge "ears," not like what is shown in the diagram.

Looks like the bands go across a solid piece that holds the rotors at the correct deployment angle. If that's the case, they shouldn't get pinched.

I just went back and looked at the parts layout. I don't see anything like that, so I see your point.

If you follow the directions and put the rubber bands where they are supposed to go you won't have a problem since there is nothing to pinch the rubber bands.



John Boren

Definitely not a FAI compatible kit, for S9A the outer diameter of the rocket must be at least 40mm in diameter and 500mm long. Most FAI heli-rocs that I have seen are internal rotor designs with a sharp boattail on the tail end. As the Estes website says, it is legal for NAR competition.

This will be a neat rocket. I really like giving the "mini-Brutes" some love!!!

This is absolutely on my "must buy" list. I am finding that I really appreciate rockets that don't need wadding or chute packing. Shove in an engine and launch!

That hub design looks extremely clean, I look forward to fiddling with it.

FAI requires the duration model body tube to be at least 40mm OD, which is why nearly all FAI S9 Copters use internal blades.

The most popular and pretty much definitive classic deployable external rotor copter is the Rotaroc series dating back to August 1975.



The basic design has been copied and cloned by many.



PDF file of plans: http://georgesrockets.com/GRP/CONTE...n/Rotaroc_A.pdf

Web page instructions on how to build a limited “kit” I made up for club members one year:

http://georgesrockets.com/GRP/CONTE.../Rotaroc-A.html








That said, I’m really glad to see this kit, and will get a couple to check out.

Here’s a video of some model testing last June. Second flight is a D Rotaroc rigged not to rotate much so as not to risk losing it
(was a boost structural test and deployment test flight).
Third flight was an E9 powered test of a G Rotaroc (3 x 36” blades, BT-55), which was flown at NARAM on G12 power (and won Team Div).

https://youtu.be/Bf3yjJKRBb8

John, George,

Am I correct in thinking that this is the first balsa-blade helicopter that Estes has ever offered?

There was the plastic bladed SkyWinder and the numerous helicopter nose-cone kits, but I don't recall any balsa blade designs. Gyroc had balsa wings but was a pseudo-helicopter.


Steve

We had to use outsized fins to make ours fly right back in the day.

http://v-serv.com/usr/kits/helioroc.htm

I like gliders too, but ones not power limited. :D

http://v-serv.com/usr/kits/fdart.htm

Just Jerry

Looking forward to buying dozens of Patriots.

I believe this is the first Estes kit with Balsa blades but I'm not positive.



John Boren

Agreed but laser cutting has made a bunch of stuff possible for the E business model only plastic could do in the past. Time for a balsa glider for 29mm motors!

I found a couple of images of the real model that might help in seeing what the hinge portion looks like.


John Boren

See that elastic in the second pic all skwunched up inside the ears of the hinge? That's a potential cause of a no-deploy.

It looks like it will work fine to me....

You mean those rubber bands resting peacefully in the groove waiting for the thread to burn through so they can EASILY deploy the blades. Yes, I see that.

Anyone who decides to purchase and build on of these please simply follow the directions. I've never NOT had a blade deploy. The design gives the rubber bands a ton of leverage to deploy the blades. I used this same hinge mechanism on the F Helicopter model I flew at NSL last year.



John Boren

I agree with John. Oh, no!

Ah, thread burn-through. Well that answers another question. I'm curious to see where and how the thread is tied in. Just above the motor mount?

No the thread is much higher up to keep the blades from bowing out. I've also found that the thread burns through much more reliably when higher up. I don't know why it works better but it does for me.


John Boren

John-
Thanks for actually finding the "optimal" burn string position by actual experimentation/field-testing instead of relying on THEORY (just assuming) placing it lower "has" to be better.
I'm an engineer, and those in my field often get caught up with determining "why" something works rather than insuring/testing it DOES WORK.

Indeed. I've heard it said that "one good test is worth a thousand expert opinions". I got that one from Tom Hunt - a test engineer at Grumman who was very active in the world of RC airplanes, electric power in particular, for many years.

I said it was an FAI-type kit, not an FAI rules-compatible kit--"FAI-style" would have been a clearer descriptor.

I'm not sure it's optimal but I used to put the string maybe a half inch in front of the motor like I've seen everyone else do. I've Crashed SO MANY HD models because of the string not burning through that I started to move it further up which has the added benefit of holding the blade in, since the rubber bands always bowed them out. I don't believe I've ever had a string not burn through since moving it up. I'm sure one day it's going to not burn through my percentage of success is still going to be much higher then it ever was before.



John Boren

It looks like you found a way to increase A10-3T sales. :D

If it works reliably it is optimal.

We still love you Blackshire.... but, eh, this kit is not even close to FAI-style either.

On the other hand nobody has posted an FAI style version.

The term "Formula One race car" brings quite different images to mind (see the historical lineup picture here: http://en.wikipedia.org/wiki/History_of_Formula_One ) depending on one's age, especially if one doesn't follow the sport closely, but they're all Formula One race cars. The same is true of FAI heli-roc models (and other non-scale types of FAI space models [such as streamer duration rockets], whose typical appearances have changed over the years). I don't follow FAI heli-roc competition closely, and the pictures I've seen of such models (which date back to the 1990s, in Stuart Lodge's books) showed models that looked like the new Estes kit.

Apogee has a FAI legal HD (S9A) model. You can find it here: https://www.apogeerockets.com/Rocke...r2el4a0al1pgl77

You must be thinking of something else. The FAI S9A event originally required a minimum diameter body of 30mm, which later became 40mm. The only competitive design approach when forced to use a 30mm or larger tube, is to go with internal rotor blades.

Now, I do recall some article by Stu Lodge, about copters, which included an external bladed model, but it was forced to use a 30mm (or 40mm) main body, so it was huge, draggy, heavy,and not competitive for FAI. Now, he may also have shown some non-FAI copters, which naturally would indeed look like Rotaroc designs - with skinny body tubes (main tube diameter = engine mount diameter).

Now, there my have been one "FAI" external blade design he had a photo of years back, where the blade airfoils were something like 120 degree arcs, and when folded, it created a 40mm diameter tube, sort of. However, that design would have been easily protested as the FAI body is supposed to be continuous, no air gaps. If I am recalling it correctly, then most likely nobody else protested it since it didn't perform well enough to be a contender (strategically allow a competitor to keep using a dead-end design rather than protest it and force them to design something better that might win). I sure never saw one like that actually entered in a WSMC, most likely it was flown at the British version of "NARAM”, or local contest.

You've gotten the impression either from the image of a poor design that did not perform very well, or images of non-FAI Copters (NAR contest type copters) and think that's what the standard FAI copters have been like.

I already posted pictures and plans of what Rotarocs (dating back to 1975) look like, which is the basic design of what this new kit looks like.

As for FAI Copters (S9A Gyrocopter), they look more like this (at launch):



Note that the main 40mm body of this particular one is Kapton, a brown-orangish transparent tube, so the folded balsa blades are seen inside. Below that is a fiberglass tailcone/engine mount assembly. Usually the bodies are all-fiberglass, built very lightly.

And they look like this after deployment (model on the right.....)

Thank you, Mike and George. No one, I suppose, is attracted by all facets of any hobby (the great variety of aeromodels, from indoor microfilm "slow flyers" to turbojet-powered scale models, and everything in between, demonstrates that), and while heli-rocs aren't my thing, I can appreciate the difficulties and design trade-offs that are involved in getting them to operate reliably and at the highest possible levels of performance.

George,

If I am not mistaken the original Rotaroc design came from you, is that correct? I think NCR did a version of it years ago and Fliskits currently has a version. Would you mind giving us a bit of history of how it came to be, modifications, etc. I'm also not sure where Art Rose's version came in.

What I do remember is that the first competition helicopters Emma and I ever built (terribly) were your designs and we flew them (terribly) at our first team tryouts 10 years ago. Our flights were so bad that you came over, unasked, and helped us tweak them to at least get qualified flights. We have never forgotten that kindness. :)

Steve