RC India

Finally After many years of desire and thought process! Yesterday finally I got my Funjet.

Was eyeing a funjet on RCD... after lot of to & fro I finally decided to go ahead with one.... :banghead: and the day I wanna buy it went backorder. Once decided now no looking back so start searching other options....and finally I found one with Areo Engineering Works.

Called them many times before going ahead to understadnt the motor requirement, shipping porp reuqirement etc.

I found them very cooperative and helping. Disucssed with many flying buddies and got a posivitve feedback about them and This thread to endorce their good work and prompt response.

Yesterday got my FUNJET herewith are picturs.

I welcome suggestions/tips/ advice on this model from expert flyers.

The combo I am planning to install is:

Motor 2826/2200 kv
ESC- 50 AMp (Birdie)
6X4 Prop
3s 20c 2200 Mah Battery





Sanajy Rai sir's take is it will be flying ladies style  :giggle: :giggle: with this electronic combination.  So will upgrade soon. Need expert advice on this.

 :thumbsup: :thumbsup:

Put a 3700 KV motor on it..........be where the Big Boys play  ;) ;D

@sanjayrai55
At 11v say 40k rpm on 3700kv
Or say 660 rps
Or say 220 fps pitch speed on a 4" pitch
Or say 250 kmph
Am i right?
Or am i stuck inside of Mobile, with the 10pm blues again?

No

 ???
No to which one?

No means no.... Its Boltz rule when Rai sir say "no" then know more questions.

I'm interested how your funjet turns out.  I just started my build on my 4th Skyfun.  Parts I already have on hand Turnigy 2836 2300 kv. 40 amp ESC, 2200 mah 4S lipo.

I'm asking Rahul if we can fly on his field, hoping we can have a race.

I also have a speed measuring device from my baseball gear so we can see exactly how fast these things performs.

Will yours be ready in 2 weeks?  

Right. I note. Know more questions.

@theleabres
250kmph?
You'll probably know these references, like
Riding 90 miles an hour down a dead end street...
I suspect sanjayrai55 has gone to bed...

Well, if the airspace is limited I may uses a car ESC and toggle reverse thrust mode to slow down.

If it happens, for sure there will be a Youtube video.  After that, organizers can introduce pylon racing.

Warning: don't race your plane if you can't afford to lose it all.  At these speeds, any loose control surface, horn, weak wing joint will be tested to its limits and the smallest miscalculation will result in catastrophic failure.  Then it's goodnight go to bed.

Reference quote:  Your Ego Is Writing Checks Your Body Can't Cash

 

+1 to Rai Sahib and to Saurabh. Two alphabets sum up a wealth of advice. I love this!!! :rofl: :rofl: :rofl:

I 'know' that there are NO more questions...............

@Lance -

Reference Quote - You don't have time to think up there. If you think, you're dead.  :P

My posts of my funjet is there somewhere. Look for it. Few issues. Don't launch it with full power she will run out of hand. See my post on maiden woes. I have covered how to toss etc. At throw you will need full recommended throw, not the reduced control throw. It has Adverse aileron drag (see my basic aerodynamics thread ) to counter that throws recommended in the manual is differential (that is different throw for up and down) follow that throw. After take off she picks up speed quite quickly. Control speed else change over to low throw else she gets very sensitive. Any other issue ? You could flag the same.

One other thing I have flown funjet and funjet ultra, both are easy to fly compared to FJ FJU is faster but flyable. Don't get intimidated. FJ is a peace of cake

Many thanks experts for their kind words and tips.


@theleabres sir I am already up and flying. It took a night to complete it. And the right comparison for this model is its a Maruti 800 fitted with a Ferrari inside.

Awesome floating capability with Commendable speed. Very reasonable power consumption and with a 3s 2200 20c battery and 2826/2200 kv motor you can fly it for about 10-12 minutes with a mix of high speed passes and glider like floating.  Sir, your most welcome to our field in Gurgaon and we would be obliged to have you with us.


@Gusty sir, wonderful tip to remember for this model. I kept it in mind while doing maiden & it really picks up after launched. As you said its no doubt a piece of cake and really a forgiving model.

Many thanks Sanjay sir for his final touches to the model; beleive me untill he touches the models I fly, they never fly safe.  ;D. After my models got his magic touch they become my bread & butter models  :thumbsup: :thumbsup: and Bolts knows what bread & butter model is all about.  :bow:

Nice flying today Arvind  :thumbsup: :thumbsup:

http://www.youtube.com/watch?v=9tcWvPywaT4# (http://www.youtube.com/watch?v=9tcWvPywaT4#)

Good video. Looking forward to flying with you in Gurgaon.  Thanks for the invite.

After 30+ sorties on this funjet; I am facing a serious problem :banghead: with motor.

I got a 2826 2200KV motor with funjet from Aero EW. They suggested I need to re-fit the motor shaft in order to make funjet ready.

After I did that with in 5 sorties Shaft got cut.

I changed motor with an EDF motor which was 4200KV. In 10 sorties Its shaft also got cut. I changed the shaft result was same after few flight.

Today again I flew it on old 2826 with a new shaft and it was also sliced in the air.

Interestingly all shafts were sliced in the air.

Any views??? What motor I should use for it now??

You might have some slight chafing between the mount and shaft.  I can't think of any other reason how the shaft would get sliced in mid-flight.  That or there is a slight vibration during the flight that is enough for the mount to touch the shaft.

You could try and static test but wear protective clothing in case the problem is duplicated on the ground.

Shaft touching mount is zero chance sir. On observing its evident that it was sliced by its own C-clip. But id C Clip is slicing it then what should be the way out?

Very strange since I've never seen that with any motor.  The factory places those c-clips and performs quality checks.

It's a pusher.  If you reversed the shaft, the c-clip should not have any pressure.  The grub screw holds the shaft in the flat spot. On my SkyFun setup, I can't imagine how the c-clip  would cut the shaft.

If you can a take a macro shot it would be helpful.

I would stay away from Aero EW brand.

Instead of a circlup, using a collar (with a grub screw) should solve the problem

"Instead of a circlup, using a collar (with a grub screw) should solve the problem"


yes it should... but when we have forces as high as 3 mm shaft breaking..( The shaft is not getting cut it is breaking)
will grub screw be able to hold such forces...!!!

here is the macro view..... the shaft is brand new with a machined Circlip groove with a brass washer in between bearing and circlip & the washer is resting only on the inner ring of bearing.


This issue is so grave that entire BOLTZ ( our group) is terrorized.

You said 'cut' and 'slice'. :headscratch:
Did the shafts break or not?
If so, at which place?
Or did the shaft get cut/sliced at the C clip groove, leading to a small back portion falling off / rear bearing coming off etc

Been looking at my motors. All have at one END. where there is not possibility of a bending load.

In your picture, the clip/groove appear to be BETWEEN the motor and the prop.
This becomes a WEAK LINK.
Any vibration from the prop, however imperceptible, WILL lead to a fracture.
I presume you are turning over 20,000rpm

See my pics. Groove at one end, not between motor and prop.
While reversing the shaft, did you use a different shaft?
Or did you grind a groove for the clip?

Sir, In funjet you cannot put the motor as you are holding.....it has to have the shaft on other side and the motor fits to the motor mount of funjet.

Shaft which we put was a shaft used for ODIN motors from RCB.... 3.17mm with machined groove.


so far 3  shafts are Broken from the circlip groove.... see the motor Pic above ... when we put the prop it is pushing shaft inside motor and circlip is preventing that.

Entire thrust of motor is resting on circlip... cannot figure out is that force so high to break shaft???

or excessive heat at that point can help in breaking shaft since its the Circlip groove which gets heating and becomes the weak point??

Been looking at my motors. All have therove at one END. where there is not possibility of a bending load, and NOT BETWEEN motor and prop.

In your case the clip/groove is BETWEEN the motor and the prop.
This becomes a WEAK LINK.
Any vibration from the prop, however imperceptible, WILL lead to a fracture.

While reversing the shaft, did you use a different shaft?
Or did you grind a groove for the clip?

Not able to understand how you got a shaft with the groove between the motor and prop.

Should have put a washer and a collet. Doubt if even that needed.

Edit
"Entire thrust of motor is resting on circlip... cannot figure out is that force so high to break shaft???"
It is a bending load, not thrust load, that is breaking the shaft.

kindly see the pictures and advice.

These two motors saw two shafts sliced.

One motor where we reversed the shaft; I can understand that There may be a fracture because of the groove we created. Other motor has a factory fitted C clip with a washer on the shaft;

All those who use a funjet please advice; what could be the reason. I am down with 4 shafts. Planing an inrunner this time.

Just a thought ... Have you used the same prop adapter / spinner

@asinghatiya
The first pic is proof of what i said.

Regarding second pic, please post a pic of the other side of the motor too.
What motor is it?

Ctd.. With all the shafts ... If the adapter has some eccentricity the shaft is bound to fracture ...

If you carefully study the shaft break point, it is a metal fatigue failure

Arvind is correct, although he might not have framed it correctly

The motor thrust pushes the shaft. The side of the groove is subject to wear.

Then the shaft ''rebounds'' back. This cycle is repeated

This leads to a metal fatigue failure

Fatigue occurs when a material is subjected to repeated loading and unloading. If the loads are above a certain threshold, microscopic cracks will begin to form at the stress concentrators such as the surface, persistent slip bands (PSBs), and grain interfaces.[1] Eventually a crack will reach a critical size, the crack will propagate suddenly, and the structure will fracture.

When a new groove is cut in the shaft, by jugaad as there is no machining centre available, the edges of the groove are not properly rounded. These edges and corners act as stress concentration point

(3rd year Strength of Materials, IIT-B :D )

By using a sleeve, this could be avoided

Waste of time posting pics and debating. Arvind, try the collet/sleeve

@sanjayrai55
Sir,
With due respect, kindly see pm.

Dear Iyer Sir & Sanjay Sir, I guess the reasons you both mentioning is perfectly fine. SO should I use a inrunner now?? As in funjet ultra  an inrunner is recommended.

ummm.... a picture is worth a thousand words and usually saves times than typing a lengthy description.

placing a collar at the spot is not a good idea.  The collar would push against the washer or the bearing.

here's the back of my clone Funjet, a Hobbyking Rad 800.

As you can see, No c clip and no collar. All the force is on the short shaft.

@theleabres
Was wondering where you were.
Quote from my earlier post:

"Should have put a washer and a collet. Doubt if even that needed"

in your case, motor is mounted straight. If pushed by a propeller it wont get hurt;  in the case of funjet where the same motor is mounted in reversed position; in this case thrust is completely on a C-clip.  

Its a unique case and after lot of search on internet I found a funjet is recommended with an inrunner.

Okay, try an inrunner.  I have my speed measuring device on hand now.  Will your funjet be ready to fly next Sunday at 7:30 am?  If so, let's race the stock Skyfun and Radjet against it.

 >:D AWESOME, will let you know.

Today I did the maiden on my Hobbyking radjet (funjet clone).  The stock setup measured 52 mph.   I don't have the space to do a straight and level pass to get a more accurate reading.  It seems she is capable of 60+ mph.  I hope to get out to Gurgaon next Sunday to enot the field there.

Looking forward to your visit Lance....

This evening I clocked my RadJet 800 in 45 degree full throttle dive at 79 mph = 127 kilometers per hour.

Still planning to take it to Gurgaon after my friend returns from the U.S.