Whirl a While - A Helicopter Duration

[JAL3]

This time the rocket took off and flew straight and high. Having the rotors folded back really improved the stability. I waited for the rotors to deploy but I waited in vain.

 

[JAL3]

The blades never deployed and the rocket became a lawn dart. Upon impact with the ground, the blades did deploy. Two of them broke free from the hinges but things were getting better.

 

[JAL3]

I used some more CA to replace the hinges. The burn string had not burned through last time so I decided to try the polyester this time. I had time for one more flight and loaded up again.

 

[JAL3]

This flight was in all respects a repeat of the previous one except except that this time the wood of the blades broke.

 

[JAL3]

On the last flight, the burn string again did not burn through. I wondered if I had mistakenly loaded A10-Ps instead of A10-3s but all of the casings said they were supposed to have 3 second delays.

There were 2 traditional helicopters designs entered in the contest. All of the others were Applewhite paper rocs. One of the copters shredded and mine had a time of 4 seconds. All other qualifying flights were done with Stealths.

My Whirl-a-While is beyond repair. I need to build something else before 13 March. Its going to be a busy few weeks.

 

[georgegassaway]

I suggest a Rotaroc, and elastic thread.

Also, put the burn holes just in front of the motor.

While an A3-4T might be a bit long of a delay, the A10-3 causes a lot more aerodynamic stress (and a lower boost). If the bird that shredded used an A10, then it might have held up with an A3.

- George Gassaway

 

[JPVegh]

I suggest a Rotaroc, and elastic thread.

Also, put the burn holes just in front of the motor.

While an A3-4T might be a bit long of a delay, the A10-3 causes a lot more aerodynamic stress (and a lower boost). If the bird that shredded used an A10, then it might have held up with an A3.

- George Gassaway

The bird that shredded did indeed use an A10 but it didn't shred in the excepted use of the term. In fact the A10 CATOed at the push of the button raining balsa and paper over the launch area. A quick post mortem showed that the entire lower portion of the rocket had blow apart. As we were cleaning the area at the end of the day I found the motor casing, it was hollow all the way through, the nozzle had blown completely out. The irony is that I was going to purchase a pack of A3s for this event but I had the A10s in my box and figured why not? Well I found out its probably not a great idea to use 17 year old BP motors, let alone in a competition lol. Had the motor burned correctly I suspect that it would have shredded anyway or suffer some other failure. My homemade paper tube hinges were a weak point in the design and prone to failure. I have already begun the Mk2 design.

 

[Zack Lau]

You might consider rebuilding the rocket with shorter blades--cutting away the damage.

 

[JAL3]

You might consider rebuilding the rocket with shorter blades--cutting away the damage.

The blades were already shortened once.

Its kind of moot now. The carcass is gone. I'm disappointed not to have been able to make it work. I know the issue was me and not the design.

Right now things are hopping. I have to take a look and see what I actually have parts on hand to build.

 

[Micromeister]

John:
Trying to build and have operate a very complicated model is almost always a recipe for heartbreak in any type competition. particularly ture in HD models.

May I second George's recommendation of a Rotaroc for your next HD contest or sport flying attempt. you'll find it is a GREAT alternative to the more complicated folding rotor designs and WILL get you more qualified flights. with just a little luck you may very well make the podium.

I also strongly support the use of elastic thread with your HD models. it's a little more of a pain to get the tension right but if placed in the ejection path it will burn.

Another suggestions is to pre-stretch each rubberband just before attempting to install it on your model. Can't tell you how many rotors i've snapped by not doing this simple preperation step.

Let me say also. After more the 20 years I'm still flying the same 13mm rotaroc I built in 1990. It was my first Rotaroc, It's had some stifferers added, Hinge stops and hinges changed a time or two and one rotor replaced but it's still going and getting very nice times.

Like most skills; HD is a progressive learning platform. Free hub, moveable fin cans, folding and/or flop rotors are advanced designs that need a little more experience before they are tackled individually, let alone combined.
Hope this helps.

 

[JPVegh]

John, having seen your HD model and seen it fly I thnk you were on the right track. I was surprised when you told me that there were no tying instructions included in the plans because IMO this is where you were having problems. Before I built my HD entry I read as much as I could find on HD models and found several different techniques for tying down the rotors this is also where I learned of using elastic thread. I kind of feel bad that I didn't share more of what I read on this with you, specifically the technique that I used to tie down my blades. Chalk it up to me being a relative newb to the club and not wanting to step on any toes of the senior members and that I had no more real experience in this than you did. That said I think that you had a rocket that could have flown well and deployed as designed with a minimum of tweeking to your tie down techniques. There is alot to be said for the KISS princible especially when you are competing in your first sanctioned events but I can't fault you for building a complex HD model since I did the exact same thing. At least yours got off the pad.

 

[mwtoelle]

I'm surprised nobody mentioned Apogee's Heliroc. It is a 13mm Rotaroc style HD model with all of the parts in one place.

 

[JAL3]

John:
Trying to build and have operate a very complicated model is almost always a recipe for heartbreak in any type competition. particularly ture in HD models.

May I second George's recommendation of a Rotaroc for your next HD contest or sport flying attempt. you'll find it is a GREAT alternative to the more complicated folding rotor designs and WILL get you more qualified flights. with just a little luck you may very well make the podium.

I also strongly support the use of elastic thread with your HD models. it's a little more of a pain to get the tension right but if placed in the ejection path it will burn.

Another suggestions is to pre-stretch each rubberband just before attempting to install it on your model. Can't tell you how many rotors i've snapped by not doing this simple preperation step.

Let me say also. After more the 20 years I'm still flying the same 13mm rotaroc I built in 1990. It was my first Rotaroc, It's had some stifferers added, Hinge stops and hinges changed a time or two and one rotor replaced but it's still going and getting very nice times.

Like most skills; HD is a progressive learning platform. Free hub, moveable fin cans, folding and/or flop rotors are advanced designs that need a little more experience before they are tackled individually, let alone combined.
Hope this helps.

I do appreciate the advice. My choice of this rocket was based upon a combination of what I had to work with and appeal. It looked interesting to me. I understand the complications lead to unforseen problems but they were learning experiences as well.

As to what happens now, that depends on what materials I have available and time. Right now I am not certain I will be able to get anything completed on time.

 

[JAL3]

John, having seen your HD model and seen it fly I thnk you were on the right track. I was surprised when you told me that there were no tying instructions included in the plans because IMO this is where you were having problems. Before I built my HD entry I read as much as I could find on HD models and found several different techniques for tying down the rotors this is also where I learned of using elastic thread. I kind of feel bad that I didn't share more of what I read on this with you, specifically the technique that I used to tie down my blades. Chalk it up to me being a relative newb to the club and not wanting to step on any toes of the senior members and that I had no more real experience in this than you did. That said I think that you had a rocket that could have flown well and deployed as designed with a minimum of tweeking to your tie down techniques. There is alot to be said for the KISS princible especially when you are competing in your first sanctioned events but I can't fault you for building a complex HD model since I did the exact same thing. At least yours got off the pad.

Jeff, you have nothing to feel bad for. I appreciated the advice and help you gave.

Don't worry too much about stepping on Alamo Rocketeer's toes. We are generally pretty laid back and not too formal about things. What you need is a really thick skin to take the ribbing. Stu has been around longer than me but I still carry a tape measure in my box to measure his altitude attempts; it's just a six footer since I tell him I don't need to carry around the 25' ones. He takes the kidding well. They get me for other things but its not my place to discuss them here.

Having been an engineer, I very much believe in the KISS principle. One of my character defects, however, is a great love of Rube Goldberg devices. When you take a chance on complicated gear, you set yourself up for problems but it is sweet when it works. At least I assume it will be some day when it does work.

 

[JAL3]

I'm surprised nobody mentioned Apogee's Heliroc. It is a 13mm Rotaroc style HD model with all of the parts in one place.

That kit or any other would be very welcome at this point. Now though, its a matter of what's one hand and even that is doubtful.

 

[gdjsky01]

I have to finish reading this entire thread but it's been great. I built a Chicago Chopper designed by Pavel Pinkas. I built it a few years ago, then things went into storage. Now its back. It's my first Helicopter recovery attempt and it's been very challenging. First everything breaks. Whether assembling it, transporting it, or prepping it, I seem to find a way to break something. Second... well... see the first. It's like the only time nothing breaks is when it's flying.

The first flight was great on a 1/2A3-2T!

Well, sort of. Great in that
A) Nothing broke :smile:
B) The Rotors deployed :smile:
C) It almost seemed to spin up and get on step before landing. An A3 perhaps would have given the rotor more time to spin up.

Few things I have learned so far...

• The rotors need to be balanced, it's wobbling too much.
• The cut down DuBro hinges are a #%#%@. They flex too much and have too much slop. So I never twice get the same AOA for the deployed blades.
• The balsa 'blade stops' crush so your dihedral is not constant...

But other than that... :roll:

 

[jsdemar]

But other than that... :roll:

Holy cow, it's Jeff Gortatowsky!

To JAL: Sorry to hear about the problems with the While-A-While. I'll have to build one again (after 10+ years) and see if I can add some more details to the plans. One thing I remember is making the triangle stops out of ply instead of balsa and putting a small square of 1/64th ply on the top of the rotors where they hit the stops. Also, it's a good idea to double up the rubber bands to make sure the rotors deploy. For the tie down string, cotton is the way to go. The cutout should be close to the top of the engine.

As others have said, it's not the easiest to build for a first scratch-built 'chopper. Rotarocs without folding rotors are much easier. But, you can get much more altitude out of the narrower-bodied folding-rotor designs.

 

[JAL3]

I have to finish reading this entire thread but it's been great. I built a Chicago Chopper designed by Pavel Pinkas. I built it a few years ago, then things went into storage. Now its back. It's my first Helicopter recovery attempt and it's been very challenging. First everything breaks. Whether assembling it, transporting it, or prepping it, I seem to find a way to break something. Second... well... see the first. It's like the only time nothing breaks is when it's flying.

The first flight was great on a 1/2A3-2T!

Well, sort of. Great in that
A) Nothing broke :smile:
B) The Rotors deployed :smile:
C) It almost seemed to spin up and get on step before landing. An A3 perhaps would have given the rotor more time to spin up.

Few things I have learned so far...

• The rotors need to be balanced, it's wobbling too much.
• The cut down DuBro hinges are a #%#%@. They flex too much and have too much slop. So I never twice get the same AOA for the deployed blades.
• The balsa 'blade stops' crush so your dihedral is not constant...

But other than that... :roll:

That is an interesting plan. I've saved it and will try it some time, but not this time. Thanks for the link.

 

[JAL3]

Holy cow, it's Jeff Gortatowsky!

To JAL: Sorry to hear about the problems with the While-A-While. I'll have to build one again (after 10+ years) and see if I can add some more details to the plans. One thing I remember is making the triangle stops out of ply instead of balsa and putting a small square of 1/64th ply on the top of the rotors where they hit the stops. Also, it's a good idea to double up the rubber bands to make sure the rotors deploy. For the tie down string, cotton is the way to go. The cutout should be close to the top of the engine.

As others have said, it's not the easiest to build for a first scratch-built 'chopper. Rotarocs without folding rotors are much easier. But, you can get much more altitude out of the narrower-bodied folding-rotor designs.

You don't have anything to be sorry for. I enjoyed giving it a try and have learned some things. That is never a failure (though my wife wonders if it is even possible).

I chalk a lot of it up to my inexperince and not knowing the conventions.

Thanks for the plan.

 

[gdjsky01]

Holy cow, it's Jeff Gortatowsky!

It is John! A long ways from Action! for the Atari 800 aye??... goodness grief time flies... Rich is still in Rochester.

I see you are still active in Rocketry. Since my club is hosting the NSL, maybe I'll see you?

I thought of doing a Whirl-a-While. Goodness knows I LOVE the name! Pavel's design made so much sense, and the instruction are really good (other than no to scale plans).

I think it's important to remember, Helicopter recovery is one of the harder competitions to fly. Not only are you trying for the thermals and model returns like the B/G and R/G folks, but you have this Rube Goldberg rocket to do it with!


ChiChopper on the pad

 

[JPVegh]

I like some aspects of the Chi-Chop design, in particular no burn strings. Also setting the angle of attack with sanded balsa plates. It is an interesting desgn.