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Flame Out!

earthsciteach

Moderator
Moderator
#1
Tossed the 50 mm Mig-15 into the sky after school. She was flying nicely on a new 1500mah, 11.1V bat. About 1 minute into the flight a loud BRRRAAAAAPPP emitted fron her and she became a glider. I landed safely. When I checked out the Mig, all of the fan blades were MIA. There is a weird red-brown swirl on the fan hub. Could I have struck a bug??? Time for a fan upgrade!
 

jetpackninja

More combat please...
Mentor
#2
Nah- those Sky Angel 50mm fans are prone to the type failure you have described. It just grenaded on you.

Did it taste like bug?
 

earthsciteach

Moderator
Moderator
#3
I have yet to pull it out of the Mig. I'm busy preparing to tape glow stick on my Wild Hawk to do some night flying. If I pull it out later I'll give the hub a lick. What does "bug" taste like, anyway?
 

lobstermash

Propaganda machine
Mentor
#5
Yikes! I haven't had any issues with my Intruder, although I'm always careful to make sure the EDF is running OK (if you do the EDF hatch up too tight it distorts the casing and makes the fan rub), especially seeing mine sits on full throttle for the whole flight.

In terms of replacements, this one looks a cracker: 50mm unit

With a 30A ESC it'd turn the Mig into a rocket!
 

earthsciteach

Moderator
Moderator
#15
EDF Turbine Blade Failure Analysis Report

On the date of 3 February 2012, Mig-15 384 experienced a catastrophic in-flight failure of the EDF turbine blades. The pilot maintained control of the aircraft and was able to land safely. Initially, the possible causes of failure were thought to be a mid-air bug strike or the exceeding of the turbine's maximum design rpm due to the use of a new, 1500 mah, 11.1 V, 3s, 30C battery. Subsequent investigation was conducted and the two initial suspected causes of failure were ruled out.

An early hypothesis of failure due to mid-air bug strike was generated by evidence that presented upon initial inspection of the aircraft's fan hub. A brownish red residue was evident on the fan hub (see Figure 1).
DSCF6757.JPG
Figure 1

This initial suspected cause was evaluated with a taste test of the residue. The residue had no "buggy" taste. This, combined with a scraping with an Exacto knife revealed the residue to be of non-organic origin. Due to this, and the lack of large bugs experienced during February in Pennsylvania, this suspected cause was eliminated.

The aircraft was flying with a new power source. This power source was of a higher C rating than previously tried in the aircraft. However, the presence of the residue and the damage observed on the leading edge of the recovered turbine blade (figure 2, below) eliminated the possibility of exceeding the design RPM of the turbine fan.
DSCF6755.JPG
Figure 2

The scrapings of the residue revealed it to be a polymer material, red in color. This quickly focused the cause of failure on a component completely unrelated to the EDF assembly itself. Due to the crammed space available below the cockpit area for electronic components, persons responsible for the maintenance and preparation of flight had found it necessary to place the receiver antenna through the opening for the left wing servo wire. It is now apparent that this lead to the failure.

Immediately after the incident with the Mig, the receiver was transferred to a MK IX Supermarine Spitfire. This Spitfire was recently rebuilt with a completely new airframe. The performance of this aircraft was as expected. Therefore, the receiver was not at all suspected as the culprit.

Once the residue was identified as a red polymer, maintenance personnel inspected the receiver antenna and found the tip to be damaged (Figure 3).
DSCF6768.JPG
Figure 3

The cause of failure has been found to be the intrusion of the receiver antenna into the fan intake. This lead to the destruction of the turbine fan blades. Investigators recommend a redesign of the electronics area such that the antenna is accommodated within the aircraft's cockpit. This will be implemented upon the requisition of a new turbine fan.

In an unrelated, but perhaps relevant event, it is noted that sasquatch is attracted to red polymer materials. It is recommended that aircraft are not left out in the open unguarded. While there is no firm, scientific proof, this report finds sasquatch to be the ultimate culprit in this incident.
 

Pilot-294

Senior Member
#19
In an unrelated, but perhaps relevant event, it is noted that sasquatch is attracted to red polymer materials. It is recommended that aircraft are not left out in the open unguarded. While there is no firm, scientific proof, this report finds sasquatch to be the ultimate culprit in this incident.
since there is no finding bigfoot on this monday, ill have to drink to that haha :)
 

lobstermash

Propaganda machine
Mentor
#20
Hot diggety! So there's no receiver hatch in the aft of the plane? I was excited to see that design feature on the A-6, as it's hard enough to get the 1600 battery and wiring in the canopy. I've had to upgrade the magnet system.