How to convert 26 Hurricane to 25 Hurricane style

[Tom-TTom2015]

Hey Coaches-

We have participated a few competitions now. In order to medal in the invitational, We saw top 26FFM can fly around 2:35-2:50, and top 26Hurricane can fly 2:20ish. Those are all great times.

However, it triggered us to think that if we can build a box style 2 blade helicopter using 26 Hurricane jigs. It might be able to fly 2:30-2:40. Then, it could be able to win the first place in the invitational!

Can you help us with some ideas how to convert it?

Many thanks

[coachchuckaahs]

Your title says to convert from 26 to 25. Your text says both were 26.

I am not sure what you mean by "box style" helicopter.

While those are excellent times you have reported, I understand that both of the '26 kits in stock or near stock condition can fly over 3 minutes. There is a lot to gain through improved winding technique as well as proper matching of rubber to rotor pitch. The J&H 2026 heli is reported to be significantly better in terms of duration than the 2025 version, and is an X-rotor type which should prove more robust. It is a 2-blade rotor which qualifies for the bonus. The FFM 2026 kit is also an improvement in reported times, primarily due to larger rotors, but is also still a 4-blade top rotor and therefore does not qualify for the bonus.

Building a 2-bladed helicopter rotor is not much different than building a 4-blade rotor. You can use the J&H fixtures or make custom fixtures using Aero Martin's printable fixtures.

Wanting to build a custom heli is admirable, and much can be gained. But keep in mind that the kits are optimized through many builds by the developers. Building a custom heli introduces many additional variables, all of which can impact flight times as well as stability. It is rewarding work, but be prepared to build multiple helicopters, trying different approaches, to find a suitable solution.

Coach Chuck

[Tom-TTom2015]

Coach Chuck-

Thanks a lot! Looks realistically, we will need to first focus on either 26FFM or 26 Hurricane to fly at least close to 3:00, before considering any customization changes.

Thanks again.

[Tom-TTom2015]

Dear Coaches-

We just realized, after someone good at math helped to calculate, that @ 3 minutes level, 2 Blades can get over 20 seconds ( 10% ) bonus in the bank for free!

Anything could happen during the competition.
This ~20 seconds bonus could give us a tremendous cushion for unexpected.

That’s huge! We’ll start to build 2Blade now!

Many thanks,

Merry Christmas, & Happy New year!

[coachchuckaahs]

That is exactly why I am in favor of building 2-blade rotors. While some have experienced "better" stability with the top rotor at 4 blades, we have seen good stability with our design of 2-blade rotors, as have others.

As far as I know, the intent of the two-blade bonus was to simplify the build for students. I do not think there is an inherent disadvantage to the two-blade design, rather they were encouraging a simpler build. We saw many schools struggle to build last year. So, in my mind it is a win win: It should be easier to build to minimum weight, it gets the bonus, and it is easier overall to build and cover. The only question is whether you will have needed stability without significant experimentation. But I cannot see any reason to pursue four bladed rotors at this point. We do have last year's 4-bladed heli as a backup (same kids on the Flight team), but we now have two successful 2-bladed helis.

Coach Chuck