Thread Tools
Jul 13, 2019, 11:58 PM
Registered User
Thread OP
Discussion

Exploding JetFan !!!


Hello All,

Today I was flying my 8S Jetfan powered Freewing F16 when the fan literally exploded in midair !!, I managed to do an emergency belly landing on grass and save the airframe, although substantially damaged it is repairable.

The aircraft has flown around 15 times successfully with this setup, the motor is a Het 700-68 1500KV and max current under full load ground testing is 96A

It let go cruising at only around 60% throttle, there was an almighty BANG !!.

Now I have been flying Jetfan's for years in several airframes but have never had any problems at all, 100 % reliable, until now !!.

Just take a look at what is left of it !!........ no blades at all !!........ I have never seen any EDF fail like this before !!.
Sign up now
to remove ads between posts
Jul 14, 2019, 12:00 AM
Registered User
4stripes's Avatar
Wonder if you might have ingested something?
Jul 14, 2019, 12:08 AM
Registered User
Thread OP
Quote:
Originally Posted by 4stripes
Wonder if you might have ingested something?
In mid air ?, I don't know what ?, insects are the only thing I can think of that I would not have seen, but an insect damaging an EDF enough to cause catastrophic failure ?, I wouldn't have thought that was even possible ?.
Jul 14, 2019, 12:54 AM
Registered User
demetrius's Avatar
Is it possible sometime in the past you may have had possibly hard landings for some reason? Possibly minor fracturing the fan in the past?
I'm not accusing you I'm just trying to think of the possible reasons for this.
Latest blog entry: "Is that a Turbine?" Not...
Jul 14, 2019, 01:12 AM
Dont forget the velcro straps
corsair nut's Avatar
A big bug would have done it. Once 1 blade goes..they are all gunna go. Ive been flying jetfans for years now too...some at insane power levels... (6kw or so..on a 80mm...) a d never had a failure. Fod is the oy logical answer i see here. Glad you got it down safe.

Was it running smooth before it went?
Jul 14, 2019, 01:18 AM
Registered User
Thread OP
Quote:
Originally Posted by demetrius
Is it possible sometime in the past you may have had possibly hard landings for some reason? Possibly minor fracturing the fan in the past?
I'm not accusing you I'm just trying to think of the possible reasons for this.
Thats a good call but no hard landings in the past and totaly smooth running up to the failure point.
Jul 14, 2019, 01:23 AM
Registered User
Thread OP
Quote:
Originally Posted by corsair nut
A big bug would have done it. Once 1 blade goes..they are all gunna go. Ive been flying jetfans for years now too...some at insane power levels... (6kw or so..on a 80mm...) a d never had a failure. Fod is the oy logical answer i see here. Glad you got it down safe.

Was it running smooth before it went?
LOL I dont think we have any bugs big enough in the UK !! maybe it was a foreign visitor

Yes, totaly smooth, no issues and not massive power either, less than 3KW.
Jul 14, 2019, 01:45 AM
Registered User
Thread OP
I will have to speak to Rainer at Ejets and see if I can get a new Rotor and rebuild, the housing looks undamaged and the motor is not likely to be damaged either ?
Jul 14, 2019, 01:56 AM
Registered User
Kudi's Avatar

open duct?


No bugs big enough in the UK?
Ok... But maybe there are loose parts big enough inside the fuse that could have been sucked in by the fan?
(I tell by bad experience )
Kudi
www.keiro.ch
Jul 14, 2019, 03:25 AM
TeamSiam

Loose parts


Quote:
Originally Posted by Kudi
No bugs big enough in the UK?
Ok... But maybe there are loose parts big enough inside the fuse that could have been sucked in by the fan?
(I tell by bad experience )
Kudi
www.keiro.ch
Hello to all my friends,

Seems that the fan sucked in an object, lost in the fuse. Search the inner side of the carbon tube for scrub or brush marks in the area of the rotor. If a piece of a cut cable, or a piece of hard plastic like a thin sheet, was gliding into the gap between rotor and tube.

Starting from V2 in November 2011, we have one of the stiffest, fiber reinforced materials for the blades and stator kernel.
If the rotor explodes at 8s - 60% load, there only could be a FOD destroying the rotor.

We also made try out's with 14s and 150Amps at the 90er, as some of the sailplanes with retracting fan units do need that power level, and they are flying now since 5 years with that power level and RPM's.

Some time i get them back to change a motor, and so i can see the rest of materials they sucked in. Maybe at the start procedure, maybe in flight. And i found parts of bees, sticking at the end of the tubes, and particles from sand as well as lots of grass inside.

Am pronouncing today the new JF-80 V3 and 90 V3. Still the same materials, as they are proven!

A nice weekend to all of you,

Rainer
Jul 14, 2019, 04:46 AM
Registered User
Perhaps it is worth remembering that the fan of such an EDF is very highly stressed.
Unless expensive aircraft quality manufacturing and inspection techniques are employed a random failure is always possible.
This can be made worse by the fact that the EDF may be "buried" within the fuselage which can introduce harmonic airflow disturbances that place additional loads on the blades.

It would appear in this instance the casing did its job and fully contained the fan blades.
Jul 14, 2019, 08:05 AM
Registered User
Comrade_D's Avatar
Got boxes of failed Delta-V Eflite fans. All statically and dynamically balanced. Sometimes they last 40 hours - sometimes 5 flights. Sometimes they even run fine with a majorly chipped blade.

Had Freewing Mirage fan take a June bug on take off, no problems.
Jul 14, 2019, 09:19 AM
Classic jets rule
AIR SALLY's Avatar
It appears there is a greenish tint at the 3oclock position in the pic.....could that be grass or bug guts??
I have been flyin Jet Fans since they came out...i even have a V1 90mm on 8s never had an issue. Only fan i use, I love my JetFans.
Jul 14, 2019, 10:18 AM
Lithium Member
Herb's Avatar
Quote:
Originally Posted by Paddy Morgan
... flying my 8S Jetfan powered Freewing F16 when the fan literally exploded in midair ..
Most likely you ingested something on a previous flight, which weakened the rotor and possibly threw the unit of of balance (and which might have affected the mounts as well).

Rodger is right that there seem to be some green marks on the shroud ...

Also, one of your mounts was improperly glued, and failed.

My experience is that the JetFan 90 is very strongly built, and unlikely to just fail on it's own ...

Btw I have the same setup you have in my FW F-16, two years now,

https://www.rcgroups.com/forums/show...reewing&pp=100

.
Last edited by Herb; Jul 14, 2019 at 10:27 AM.
Jul 14, 2019, 11:20 AM
Registered User
Lynxman's Avatar
Good job saving the airframe. That's always hard to do on the fly with no time to think.

I guess even Rolls Royce engines can fail. Hard to say what happened. Could be something came loose from the plane, something lodged in the cheater grate, fatigue from a previous FOD ingestion or a freak collision with something in the air.

The greenish tint looks like a product of the white balance to me.


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Exploding Multirotor Props thereal_stickboy Multirotor Drone Talk 3 Mar 25, 2016 01:34 PM
Discussion Dark Money.........my head almost exploded rockyboy2 Life, The Universe, and Politics 24 Mar 15, 2016 07:18 AM
Discussion Oh man, I can hear the heads exploding now Sonny McGhee Life, The Universe, and Politics 14 Dec 25, 2015 10:12 PM
Help! I builed a quadcopter , but my esc is exploding. DaniR Beginner Multirotor Drones 2 Dec 13, 2015 02:19 AM
Discussion Trump explodes after another alleged Fox News snub Sonny McGhee Life, The Universe, and Politics 71 Sep 23, 2015 04:35 PM