Videos:







Please keep in mind those are pretty old videos. I assume my skills improved and now I fly it much much harder and at higher RPMs.

 

A synergy E5 with a E7 boom slapped onto it will be pretty close as well! The E5 uses Mod 1.25 delrin TT gears so you won't get the tail problems either.

 

Great idea. Thank you. I wonder if E5 TT gears will fit Align 600 CF/ESP/PRO front tail case.

Can you provide some dimensions please?

This looks promising:
http://mattbotos.com/store/index.php?main_page=popup_image&pID=1906

This one can require some work but effort is worth it:
http://mattbotos.com/store/index.php?main_page=product_info&cPath=4_32&products_id=1905

Such discoveries are priceless. My coleague Szelma discovered simple way to use 700 main gear in old Align 600 frames. We use T--Rex 500 heads in Gaui X5 to get rotor lower etc.

 

I hear all the time opinions underlining advantages of:
- belt transmission
- "monoblock" design
- double stage transmission
- "innovation" in frame design

Do we really need all of the above?

Watch this video:

Now lets have a closer look at Gaui X7 design:
- no belt
- no monoblock
- single pinion and main gear





Any conclusions?

I do prefer:
- low weight (narrow frame, no monoblock)
- simplicity (single stage)
- less friction (no belts, no double stage gears)

Now look at this poll:

 

Please look close at those frames.

Starting from the left:
- Gartt GT700 (for size comparison)
- HK600GT
- HK600GT modified to fit 700 class motor, push-pull bearing removed (I use this one)
- Align 600 GF
- Align 600 ESP (direct to swash setup requires cutting holes for servos closer to the main shaft)

HK600GT is based on Align 600 CF frame. It is older design than Align ESP. Advantage over ESP is no need for modification for direct to swash setup.

$51.30:

If you want to get one above keep in mind we will replace two upper main shaft bearing bloks with Align 600ESP and boom hoder because this one supports only belt.



Direct to swash:


Three main shaft bearings:


I do have Align 600 EFL PRO. You can wonder why I prefered to stretch HK600GT. There are three simple reasons:
- 600 PRO will not accept bigger motors. Lack of space.
- 600 PRO motor mount is not adjustable
- HK600GT frame is extremely cheap



Stay tuned... more surprises to come.

 

You might not need a 2 stage transmission and all those fancy features but then you think do I need a helicopter at all?
Thin frames means the packs will need to be mounted on the side which will give them very little protection in a crash and puts more stress on the frames in aileron movements, belt setups are almost always lighter than a TT setup, 2 stage transmission adds very little friction but when designed correctly will be lighter than a single stage, offer much more gearing options and potentially reduce the moment of inertia for much better rotation.

 

@Min sure you are right. I do agree with you. Just watch again Dunkan video, please.

 

Not quite sure what your point is...

 

I will give you example. When we look at different 700 class helis most of them have 12mm main shafts.

Not all of them. Question is: "Do we really need 12mm main shaft in 700 for smack?"

Look at Compass 7HV video, it has 10mm main shaft:

This video was recorded in 2011!

When I look at "innovative" 700 helis with 12mm main shafts I wonder why they are so heavy? Not all of them. Protos Max seems to be an exception.

 

If you hollow out a 12mm shaft to the same weight as a 10mm shaft it will be stronger, if you make a 12mm shaft the same strength as a 10mm shaft it will be lighter. Using a 12mm shaft also means bigger mainshaft bearings so of course you can smack a 10mm shaft hard but you'll be replacing those bearings more often than a 12mm shaft setup or if you smack into the ground those 10mm shaft bearings will be notchy when the 12mm shaft bearings may be ok. Most designers do things for a reason and designing a heli is always a compromise between many factors.
7HV isn't known for being light BTW

 

HK600GT main shaft is hollow.

 

Sure, now model up that shaft in solidworks and do a simple bearing load test on it, then increase the outer diameter by 2mm and hollow out the inside more to keep the weight the same and do another bearing load test. You will find the larger diameter and more hollowed out mainshaft will show less strain and have a higher factor of safety than the smaller diameter shaft for the same weight and length.

 

700 DFC:


600:


Low weight 700 can use much lighter lipos. 4Ah vs 5Ah to get around 5.5 min flights.

Additional weight with the same 700mm blades requires in heavy weight setup:
- higher RPM
- bigger heavier lipos
- stronger ESC
- stronger heavier motor

Heavy weight and higher RPM put much stronger stress not only on bearings.

Bearings in stretched HK600GT were not replaced for over two years.

After hundreds of flights they start to make more noise but who cares? I did not crash often so this helis are smooth like butter. After landing rotor rotates by innertia much longer than in any belted setup.

 

I have attached 2 reports that I have generated on some FEA that I conducted. Have a look though and take note of the max stress and weights on the 2 shafts. I have made the scales for stress identical for both models with the max being 710 megapascals can minimum being 0. The material is AISI 4030 normalised steel. Identical fixtures and loads were applied.

 

Addressing your weight problem, there is a thing call disk loading which is very important in making a well flying helicopter. Not enough disk loading will cause the helicopter to feel unstable and floaty while excessive disk loading will cause the helicopter to feel unresponsive and sluggish. I have first hand experience regarding disk loading. A long time ago I was testing the 12S Chase 380 which is the same weight ready to fly as a Goblin 380 empty (no battery). This to you may sound great as its super light but when I tried to do piro flips the helicopter will not stay in the same spot and do piro loops instead. This was because the helicopter was way too light. After batteries of double the original capacity were installed the helicopter flew much better and was much easier to control. Lighter isn't always better but a lighter airframe will allow more weight for packs which gives a longer flight time.

 

Olivion was designed to have "Low disc-load of around 1.36kg/m2":

Author wrote:
"The design goal is a 300ish size helicopter that would lock in nicely on pitch and provides full 3D capabilities – all at 2.200 RPM. This results in less mechanical wear, lower noise level and light-footed flight characteristics. You will dare more with the Oblivion than you will with other models."

As you noticed we do not put larger lipos to have longer flights because they make our helis to heavy.

It is rediculous that for hard smack 2-3 minutes flights became a norm nowadays.

Anything heavier than air is not too light.

FBL gyros make our helis very wind resistant. I can fly Nano CP X in quite strong winds for its size. It is only 28g.

I was flying low weight 700 from this thread in serious winds taking basaball hat off my head without any problems.

Same story with my Gartt 800 (3.75kg without lipos). Listen to the sound of wind on this video:

 

Note the calm conditions in the clips you have provided, you may be able to hover and do circuits your light disk loading helis but doing complex set moves in wind is a different story. When any noticeable deviation has the potential to penalise and further deductions are made for corrections to the deviations I hope you can understand why a decent disk loading is preferable in 3D flying.

 

Also this would be considered a heavy helicopter as its running 2X1400 mah 6S pack when helis this size would normally run 1.

Note the flight time keeping in mind that this is 4000 rpm headspeed on a heli thats all belt and has a 2 stage transmission.

 

Also note the power difference in the tic tocs and the cyclic response compared to the super light heli.