jacojet

Yeah! got it!

Turbotronic

Your engineer friend is 100% correct. The intake is causing severe flow separation inducing the flutter. The forces are enormous and will lead to metal failure sooner or later. Classic design error.

jgracco

I am sorry that I cannot divulge what entity he works for but I can not. It took him 30 seconds on the phone.. case closed. Look up jet engine flutter on google. If Wren or anyone wants to challenge their ignorance any further, call Boeing or anyone else in motor development and be done with this. No they did not do their homework and instead of answering the call of the issue they now have all of this information blaring them in the face for the entire world to read. Anyone take a look at the other engines? Also, why is everyone in the states hush hush about this. I find it absolutely odd that only accounts from other countries are given here.

I was being nice with my post. I feel bad for every customer. And shame on Wren.. Where is Ron Ballard on this? Pity is I could have a new intake made for this engine in a day or two. I would have helped with this at no cost but not at this point....

F86_SABRE

I suppose a keen engineer may solve such an issue. Perhaps there may be an aftermarket product by someone else that may solve this issue. Its really a waste to leave this engine on a test bed only

jgracco

It is not difficult to make a new intake. It is a heck of a lot easier than making a CNC comp wheel. Wren has not even acknowledged the problem though. Why would anyone fix their issue while they continue to charge people to just Band-Aid fix a problem that ain’t solved in the least. It was pointed out that there are a dozen manufacturers all of which never shed a comp wheel. I saw a comical response to it.. If Wren winds up with a PR problem over this (if not already)... no engineer will ever be able fix that..

F86_SABRE

Realistically speaking I do not think WREN will be solving this issue free of charge as I think that this may prove to be too expensive (i.e. their downfall) for them to do so despite their obligation (legal and/or moral) to do so given the inherent risks defective turbines may pose both in terms of health and safety risks to both the owner and/or to third parties. In terms of liability issues on the sale of a defective product I still wonder if they are yet out of the woods. This is a catch-22 situation ....if one does not use the engine (i.e. a useless paper weight) one still may have recourse against WREN but if one solves the issue and uses the engine by purchasing an after-market part replacement one will let WREN scot free. Choices! WREN's history has been impeccable, up to 160 release (and that this what made me chose this brand). However, since this issue surfaced I do now have second thoughts about their reliability and competence. As you rightly stated, they do have a PR issue which they may choose to ignore to their detriment. Whilst I do wish WREN the best of luck (they may really need it) I, for now, will choose to walk away from another WREN purchase.

jgracco

I don't own a wren and won't buy one at this point. There are plenty of other manufacturers out there without these issues to start. Wren haphazardly designed a motor that resonates itself to death... It sounds like the issue is so bad that a turbine wheel or two came apart... That is bad! Additonally, a turbine is far more efficient at 110K so it increases thrust exponentially at higher outputs. The motor is rated for 126k according to the specs. it is supposed to be a 160 newton motor. If the motor was derated to 116K then it is technically not a 160 newton motor. It might not even be a 140 at this point.

The worst part of this story is not motors coming apart; it is the ill fated way that Wren has postured themselves to handle this. I think a lawsuit and liability issues are trivial in comparison to PR concerns.

F86_SABRE

I think that the recommended maximum rpm is not to exceed 120k. At least that is what they told me. As you stated then its not a 160.

CRX Turbines

I think it is pretty evident that there might be some resonance issues here. If anyone has a guinea pig to test with, I would extend the intake and test extensively on the ground. make sure there is no resonance at the higher end.

jgracco

120 K is going to be a substantial decrease in output from 126K. I don't have a 160 testbed but I know from other engines that the increase in output in these high range of RPMs is huge for every 5k increase.

The motor should be de-rated. It just is not a 160 at 120K...

F86_SABRE

That is true as there will be significant reduction in thrust but it will be better than a paper weight!

jgracco

I never referred to it as a paperweight. I think the motor needs to some improvement to overcome some apparent design flaws.

jason

My Feedback: (1)

Has anyone got a Wren 180? Does it have the same inlet depth?

Gary Arthur

My Feedback: (29)

For what it's worth, the Simjet Nexus used the same cast compressor as the Wren 160. It also had issues blowing up compressors with about 5-6 hours on them. many people have had good luck installing the CNC Wren 160 wheel on their turbines. The interesting part is the Nexus had a max rpm of around 117-118k. Once the CNC compressor was installed, many people increased their rpm to around 121k.

One thing I noticed on my Nexus is that once the compressor was spaced far enough forward to have the proper clearance with the inlet, it left a significant step between the compressor and the front face of the diffuser. This would cause a high pressure/low pressure scenario and some shear. The shear sounds like a high pitched whine and may result in a frequency that over time could cause the resonance stated earlier.

I think that removing the shims, and moving the compressor back to eliminate the step would be ideal. This would require machining the front of the diffuser and the radius around the outside to move the inlet lack to the compressor. This would achieve a smoother flow of compressed air with less shear.

Wren has always been great to deal with and more than fair with me. They also came to the rescue when my nexus was in need of a compressor.
Just my thought.....

jacojet

The reason most of us went with wren engines is because they where great in the past. I think it is time to try and get a definite answer from wren. To solve this, and to avoid the financial implications that this might impose on wren, although I think they deserve it, might be to let wren repair the failed engines at cost. They also have to present a solution and present it to the current owners at cost. They cannot make any more profit out of these engines. That way it should not cost the current owners a arm and a leg and wren can make right without loosing too much money? Since wren does not respond on this forum, we should engage another method of forcing them to, at the very least, release an official statement regarding their stand in this.

https://www.facebook.com/pages/Wren-...54656198069224

This is wren's facebook page, here we should write a request for the above mentioned statement and also send them an e-mail requesting the same. If enough owners, concerned customers and everyone else interested do this, they will have to eventually respond. It will be very interesting to see what position they take and will probably define what their attitude will be to future customers.

Is there anyone that agrees with this plan? And if not, why not?
Any other suggestions would be most welcome!

ira d

I dont own a wren but I do agree when a company knows it has a problem with it's products they should admit to it and do right by the cumstomers that purchased
the defective products. I also think when a company makes a good faith effort and provides a reasonable solution to it's customers most will be satified.

warbird51

My Feedback: (12)

Did FEJ buy Wren?

ira d

I don't know but I doubt it.

jetmanuk

Dear Mr Strydom, I do not know who you are, or why you have sent me a SPAM message via FACEBOOK. I Do NOT own or never owned a Wren 160 Turbine.

Having taken the time to read this forum and the posts you have made i have come to the conclusion that your efforts here are nothing more than HARASSMENT of Wren turbines and their friends by a Narcissistic Bully.

I have filed a report with FACEBOOK A screengrab of your message sent to me yesterday is displayed here.

I trust you will refrain from contacting me again.

In accordance with the Protection from Harassment Act 1976 here in the UK if you choose to further contact me again you will leave me no option but to put the matter in the hands of the UK police.

If you believe you have a legitimate grievance with Wren Turbines then may I suggest that you follow civilised procedures via an attorney or lawyer.

I will of course be reporting this forum thread that you have started on the basis that you are now engaging in a manner of conduct that is Harrassing to those un-connected with Wren Turbines.

jgracco

delete the mail and/or don't respond. Big Deal.. Stop huffing jet a.. I think it might be mak'n ya paranoid....

NZjet

Drama queen much?

jacojet

Wren is not responding at all, not even when I asked that my turbine be returned to me. Don't know how I am going to get my engine from them. Must be some way I can force them to return my engine?

jacojet

OK, got hold of Mike Murphy, the MD of Wren. On the phone he sounded like a very reasonable man. A solution might be forthcoming. Things seems to be taking a turn for the better! Will keep posting.

jgracco

Well that is good.. I hope you get your issues resolved. I am not sure what Wrens issue is that they would let a wildfire burn out of control like this and not reach out to fix the issue at hand. Especially since this is clearly a design issue and they apparently do have the solution. No amount of comp wheels even if they were gold plated could possibly be worth all of the negative press that this has gotten.

Jet Doctor

Ok, Idiot #4 here. I also own a Wren 160, one of the first. I have seen and been present at 3 of the 160's that destroyed themselves here in South Africa. I could not wait for the 160 to be released as I had a Wren 54 kit build and Super Sport. Both brilliant turbines and had no hesitation in placing the order with Sarah for the 160. To our dismay, these 160's were falling apart. Unfortunately the one failure caused a total loss of a Skymaster Hawk on takeoff. The first upgrade was to replace the compressor with another cast one and change of ECU. These compressors too came apart. We could then choose to send them back for a machined compressor at our own cost - grrrrrrrrrrrr! The last two to destroy themselves had machined compressors.

I never sent mine back for a third compressor because I thought it was not fair for me to have to pay for a design fault. Mine is still running at reduced RPM(max 120K) and I have been lucky until now that it is still in one piece. Fortunately the airframe that it is in doesnt require 16kg of thrust.

So Wren turned a fanatic supporter into a disgruntled end user! Pity really as the Super Sport and XL 200's were awesome turbines.