Oops, I did it again...........570 Goblin Style

[Rudy]

Originally Posted by LoveToFly1

bc I wouldn't.

OK

[Sowa]

Originally Posted by jc23cl

Hey all,

Quick update, as promised I have Investigated the "axial fan" design and can make it work.

I reserve that although technically feasible, other components or design Issues may prohibit this variant.

But here it is, 50mm EDF fan (5-blade), geared 4:1 so that at full speed, the fan generates almost 50K RPM. This equates to more than 450 grams of thrust, this wont act to lift the heli as the motor blocks this thrust, but gives you an Idea of how much cooling is available. The shaft and bearings are very rigid, as the the fan cowl is only acting to distribute cooling air, therefore no compromise there. The fan has no obstruction from post Impeller thrust so cooling should be optimised.

Anyway here's the pics....one note is that a 6mm 3GT belt is used, same as Goblin tail drives. Any doubt that a small timing belt cannot cut it, Google Belt Drive Planer and see what a standard Planer utilizes as its transmission ; )

That's looking very promising, I wonder if there will be added power benefits from the EDF unit.

Is there anyway to add an auto tensioner on the fan belt?

[brw0513]

Woohoo Joey!!! I reckon you've nailed cooling duties with that design.

Get it done buddy!

Not sure how, but let me know if I can help in any way

[brw0513]

I've been doing some basic calculations for a project of mine recently - no real idea if I'm right

But those calcs show a 4 blade head with 550mm blades using a gear ratio around 8.3:1 gear ratio might be a good choice for this engine.

[Sowa]

Is this conversion going to use standard servos or 500 size servos? Would it be possible to choose? I'm not familiar with the differences between the 500 and 570 but I believe the servo size is.

I know using smaller servos would mean having to purchase more expensive higher performing servos but it would be another place to loose some weight.

[jc23cl]

Hey mitsudriver274,

No the 570 will use standard size servo's, cyclic and rudder.........but, I am seriously considering a small servo for the throttle. I know this may not be popular but spending a lot of effort to reduce weight, would kind eek me to have a full size servo for throttle.

If there are real objections, I'd like to hear them. Thoughts anyone, bad experiences etc.

Thanks Joey.

[fastflyer20]

A high quality mini servo on the throttle should work fine.

[Rudy]

Originally Posted by jc23cl

Hey mitsudriver274,

No the 570 will use standard size servo's, cyclic and rudder.........but, I am seriously considering a small servo for the throttle. I know this may not be popular but spending a lot of effort to reduce weight, would kind eek me to have a full size servo for throttle.

If there are real objections, I'd like to hear them. Thoughts anyone, bad experiences etc.

Thanks Joey.

As i do not see the need to run some super duper high torque, high speed servo on the throttle, I have no problem with a mini servo there. You can get a good mini servo for about 30 bucks. The Futaba S3115 is a great servo and is just $19.99.

So lets save the weight

[LoveToFly1]

the point of a fast servo on the throttle is: your throttle servo needs to be faster than your cyclic servos. if you can ad pitch faster than you can add throttle, then it is easier to bog your motor

[LoveToFly1]

and you can find many mini servos to do that like THIS one.

[Rudy]

Originally Posted by LoveToFly1

the point of a fast servo on the throttle is: your throttle servo needs to be faster than your cyclic servos. if you can ad pitch faster than you can add throttle, then it is easier to bog your motor

Your engine will never respond that fast, that's why a high speed servo is pointless on the throttle.

[Sowa]

I have no objections to running a mini throttle servo, in fact that is what I have installed on my current gasser and also what the n5c comes setup for as well.

I'm using a hitec hs82mg, uses a standard size hitec arm and weighs 30 grams less than the jr DS8717 that was in there before.

There is no need to have a fast powerful throttle servo.
A) the only load on the throttle servo is my return spring.
B) servos are rated for speed in a 60 degree sweep, the throttle servo will never move that much in flight, these tests are also done with zero load.

Anywhere that weight can be saved is a huge positive, if someone comes out with a 600 stretch kit for the 570 this may be a killer setup.

[LoveToFly1]

Originally Posted by Rudy

Your engine will never respond that fast, that's why a high speed servo is pointless on the throttle.

then I am to assume that the man who designed the N7, who gave me that exact scenario as an example, doesn't know what he is talking about? ok

the engine itself may not respond that quickly, but it will never have the chance to try if your servo is to slow.

[fastflyer20]

It is possible that a gasser responds differently than the nitro or the way a tail servo responded with a specific gov.. A friend swears you need a rudder servo on the throttle. I installed a tail servo on the Goblin using a GV1 and can not tell any response difference between a decent cyclic and tail servo.

Back to the topic at hand,
Lets encourage Joey to build a few prototypes....

[LoveToFly1]

I would like to see this bird be built. if it flys as good as the goblin 700 then that would be awesome. surely the second go around with this motor will be better, OS is an educated bunch, they have made many great motors before. this heli looks great, as does the other goblin. So when can we see a vid of the first prototype kit fly?

[Sowa]

What clutch will be used in this conversion?

Edit: re read the first post. Question answered.

Do you believe a 700 clutch is required? So far my 600 size clutch has been holding in hard maneuvers.

[brw0513]

Hiya Joey.

Any further progress to report?

[jc23cl]

Hey Sorry Guys,

Been soooooo busy last 2-weeks, work stuff. But I'm back on it this week.

To answer question regarding clutch, its a lynx Gasser Clutch with Billet 4140 Clutch Bell.

Hope to have more updates this week, thanks again all for the encouragement, I'll do my best.

Regards Joey.

[carey shurley]

Do you believe a 700 clutch is required? So far my 600 size clutch has been holding in hard maneuvers.

I would certainly recommend it. I was using a whiplash 700 clutch on my Fury 55 conversion and there were circumstances where it would chatter.

by using the larger clutch and then custom fitting the bell for a tight clearance this shoud be even better

[Sburv]

Any news....?