I Feel Ripped Off
12-12-2006, 05:55 PM
#26
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RE: I Feel Ripped Off
Just to awnser some questions, no tailpipe, open air installation, and as i stated before, it was in the high 50's low humidity, and no more than 50 ft above sea level. I will state however that although a little dissapointing, a few pounds of push be damned, i'd rather have a weak engine that runs all the time, than one that runs strong some times. It's bulletproof reliable, and that's what matters most. Happy holidays to all, Greg
12-12-2006, 06:53 PM
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RE: I Feel Ripped Off
I ran my Artes Falcon on one of those fish scales a few weeks ago.
Motor was mounted in an aircraft.
Gauge read 21.4 lbs
Taking into account the thrust loss of the pipe and wheel grab, I imagine it was putting out right around 23lbs.
I was hoping for 24
Motor was mounted in an aircraft.
Gauge read 21.4 lbs
Taking into account the thrust loss of the pipe and wheel grab, I imagine it was putting out right around 23lbs.
I was hoping for 24
12-12-2006, 09:00 PM
#32
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RE: I Feel Ripped Off
ORIGINAL: slick121985
HotelSierra,
The JetCat USA website states " 28lbs @ 123K. The results from my test: 25.5lbs @ 125K.
HotelSierra,
The JetCat USA website states " 28lbs @ 123K. The results from my test: 25.5lbs @ 125K.
12-13-2006, 03:41 AM
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RE: I Feel Ripped Off
I ALWAYS buy an engine with more thrust than is required as you can always turn it down and give the engine an easier life.
With all the variables which can change an engines thrust if the manufacturers quote figures at ISO etc then people way above sea level in hot countries will always be disapointed.
See living in england with its cold weather does occationally have its advantages we get more thrust out of the same engines te he te he.
Just my humble input
Ant
With all the variables which can change an engines thrust if the manufacturers quote figures at ISO etc then people way above sea level in hot countries will always be disapointed.
See living in england with its cold weather does occationally have its advantages we get more thrust out of the same engines te he te he.
Just my humble input
Ant
12-13-2006, 09:24 AM
#40
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RE: I Feel Ripped Off
ORIGINAL: WrenTurbines
There are accepted rules and tests for things like miles-per-gallon claims in car adverts because the car industry has regulatory bodies who make the rules and do the tests. The miniature jet industry does not have any national or international organisations with these powers.
There are accepted rules and tests for things like miles-per-gallon claims in car adverts because the car industry has regulatory bodies who make the rules and do the tests. The miniature jet industry does not have any national or international organisations with these powers.
As of 2008 models, the fuel efficiency of all new cars in the US is having to be restated following a few gazillion complaints about the lack of reality in all published figures. The new figures (with no changes to the cars, just to the formulae used) are claimed to range from 10% to 30% lower fuel efficiency than the current figures.
12-13-2006, 09:30 AM
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RE: I Feel Ripped Off
Gordon
You are bang on there, it's just the same in Europe, I have never had a car that would come within 10% of the published mixed cycle mpg and guess what? it was always LESS than the manufacturer's figures.
John
You are bang on there, it's just the same in Europe, I have never had a car that would come within 10% of the published mixed cycle mpg and guess what? it was always LESS than the manufacturer's figures.
John
12-13-2006, 09:38 AM
#42
RE: I Feel Ripped Off
ORIGINAL: Miniflyer
That you're a wren dealer?
All jokes aside, i think Sara really has a point. The problem is finding an institution with which all manufacturers are willing to cooperate (also those who are knowingly cheating their numbers). The GTBA is a great point for reference, it's just nothing that has any influence on ads....
Also, a "test engine" can be selected so that it will accually produce great figures, whilst many of the production engines come not so close to these values....
Because of the "small" number of turbines sold compared to cars, i guess there is just no large economical interest in getting law enforcement on this subject...it remains in the hands of customers to see wether their product of choice is superior or not, or if they have reason to send it back to be re-worked to specs or given a refund....
ORIGINAL: digitech
i flew a Flash with a Wren SS
it had unlimited Vertical.
what does that tell us?.
i flew a Flash with a Wren SS
it had unlimited Vertical.
what does that tell us?.
All jokes aside, i think Sara really has a point. The problem is finding an institution with which all manufacturers are willing to cooperate (also those who are knowingly cheating their numbers). The GTBA is a great point for reference, it's just nothing that has any influence on ads....
Also, a "test engine" can be selected so that it will accually produce great figures, whilst many of the production engines come not so close to these values....
Because of the "small" number of turbines sold compared to cars, i guess there is just no large economical interest in getting law enforcement on this subject...it remains in the hands of customers to see wether their product of choice is superior or not, or if they have reason to send it back to be re-worked to specs or given a refund....
take the last jetpower magazine
take the latest RCJ magzine
take the GTBA figures and please try to discover what we arer saying here..
you will be spurised about the many different figures.
engines that suddnenly lose 300 grams of weight.in 3 different tests
engines that use 40% more as advertised.
all backed up by different people.
and these figures i found in just less then 10 minutes by just putting the adds and test together...
we should point to customers to read more about test rather then what is advertised.
but then most buyers will be to embarased to really tell the truth if they did not buy a product as promissed.
i remember being banned in the past for telling the truth....
so i wont go in that direction anymore.
happy reading!
12-13-2006, 09:41 AM
#43
RE: I Feel Ripped Off
ORIGINAL: john agnew
Gordon
You are bang on there, it's just the same in Europe, I have never had a car that would come within 10% of the published mixed cycle mpg and guess what? it was always LESS than the manufacturer's figures.
John
Gordon
You are bang on there, it's just the same in Europe, I have never had a car that would come within 10% of the published mixed cycle mpg and guess what? it was always LESS than the manufacturer's figures.
John
yes but most of europe is bigger then glasgow...
with that cold and moisture in the air you get good milage ;-).
winter is the best time to sell a turbine i get most of the time 10% more thrust then advertised....
12-13-2006, 10:31 AM
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RE: I Feel Ripped Off
I have a question about one of the results from the table posted by robrow. Many engines were delivering the manufacturer's claimed thrust or more, e.g. the little Wren 44 putting out a bit more than the claimed 10lbs thrust, indicating that atmospheric conditions on the day were not disadvantageous. But the Wren Super Sport is recorded at 17lbs thrust compared to the 18lbs claimed. The reason this puzzles me is that Wren is very particular about making performance claims that everyone can expect to get, and not making claims based on one very good but rare engine. Is there an explanation why the Super Sport fielded by Wren themselves was not delivering 18lbs or 80N of claimed thrust?
Harry
Harry
12-13-2006, 10:52 AM
#45
RE: I Feel Ripped Off
ORIGINAL: HarryC
I have a question about one of the results from the table posted by robrow. Many engines were delivering the manufacturer's claimed thrust or more, e.g. the little Wren 44 putting out a bit more than the claimed 10lbs thrust, indicating that atmospheric conditions on the day were not disadvantageous. But the Wren Super Sport is recorded at 17lbs thrust compared to the 18lbs claimed. The reason this puzzles me is that Wren is very particular about making performance claims that everyone can expect to get, and not making claims based on one very good but rare engine. Is there an explanation why the Super Sport fielded by Wren themselves was not delivering 18lbs or 80N of claimed thrust?
Harry
I have a question about one of the results from the table posted by robrow. Many engines were delivering the manufacturer's claimed thrust or more, e.g. the little Wren 44 putting out a bit more than the claimed 10lbs thrust, indicating that atmospheric conditions on the day were not disadvantageous. But the Wren Super Sport is recorded at 17lbs thrust compared to the 18lbs claimed. The reason this puzzles me is that Wren is very particular about making performance claims that everyone can expect to get, and not making claims based on one very good but rare engine. Is there an explanation why the Super Sport fielded by Wren themselves was not delivering 18lbs or 80N of claimed thrust?
Harry
i belive he answered "we toulk the engine this morning of the shelf and it was a pre final engine NOT ready for shipment , we just had no final engine to test"
that engine was running at a VERY LOW temperature i believe about 420 degrees if i remember correctly ( full throttle).
and Wren will change it until the minimum thrust is there and as advertised with a normal outside temperature.
i am sure everyone who owns a SS will tell you that they will have more thrust then advertised....(according to wren specs)
12-13-2006, 11:22 AM
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RE: I Feel Ripped Off
ORIGINAL: digitech
that engine was running at a VERY LOW temperature i believe about 420 degrees if i remember correctly ( full throttle).
that engine was running at a VERY LOW temperature i believe about 420 degrees if i remember correctly ( full throttle).
Since it was turning at max rpm, how do you increase temperature and therefore I guess increase the pressure to increase the thrust, yet still keep the same rpm?
H
12-13-2006, 11:27 AM
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RE: I Feel Ripped Off
Yes - there is an explanation! I wondered who would notice that figure - well spotted, Harry.
Mike Murphy had two MW44s ready for the efficiency competition - engines he'd checked thoroughly. As you can see, the performance was slightly different despite the fact that they were from the same batch of engines. This is typical, no two engines are ever quite the same.
Richard Green, Wren engineer and GTBA member, was going with Mike to the competition. Shortly before they left work the day before, Mike said "I wonder if we should take a SuperSport?". They looked around but all the SuperSports had gone (not surprising, every one leaves as soon as it's been fully tested, there is great demand for them). Richard said "There's only the one I built this afternoon..." and Mike said "Oh, we'll take it." So they took an engine that hadn't been tested - and regretted it! The ECU was under-running, the tailcone was too big (it was running beautifully cool but down on power) and it would certainly not have gone out to customers in that condition. All engines undergo a series of test runs here and nothing leaves that isn't doing the quoted thrust. The team work on the engines until they are doing what they should, and an engine which doesn't meet the standard is taken apart and re-made.
Sara Parish
Wren Turbines
(I started writing this 45 minutes ago but got interrupted by the phone and when I uploaded this I saw Sandor had already posted the explanation, but I'll leave my post here too.)
Mike Murphy had two MW44s ready for the efficiency competition - engines he'd checked thoroughly. As you can see, the performance was slightly different despite the fact that they were from the same batch of engines. This is typical, no two engines are ever quite the same.
Richard Green, Wren engineer and GTBA member, was going with Mike to the competition. Shortly before they left work the day before, Mike said "I wonder if we should take a SuperSport?". They looked around but all the SuperSports had gone (not surprising, every one leaves as soon as it's been fully tested, there is great demand for them). Richard said "There's only the one I built this afternoon..." and Mike said "Oh, we'll take it." So they took an engine that hadn't been tested - and regretted it! The ECU was under-running, the tailcone was too big (it was running beautifully cool but down on power) and it would certainly not have gone out to customers in that condition. All engines undergo a series of test runs here and nothing leaves that isn't doing the quoted thrust. The team work on the engines until they are doing what they should, and an engine which doesn't meet the standard is taken apart and re-made.
Sara Parish
Wren Turbines
(I started writing this 45 minutes ago but got interrupted by the phone and when I uploaded this I saw Sandor had already posted the explanation, but I'll leave my post here too.)
12-13-2006, 11:37 AM
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RE: I Feel Ripped Off
Harry,
In reply to your second question, there are a number of ways to increase the temperature. One is to make the tailcone smaller. I think there are other things they do too ... but I don't know what exactly, that's not my department and they don't tell me!
Sara Parish
Wren Turbines
In reply to your second question, there are a number of ways to increase the temperature. One is to make the tailcone smaller. I think there are other things they do too ... but I don't know what exactly, that's not my department and they don't tell me!
Sara Parish
Wren Turbines
12-13-2006, 11:43 AM
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RE: I Feel Ripped Off
ORIGINAL: HarryC
I have a question about one of the results from the table posted by robrow. Many engines were delivering the manufacturer's claimed thrust or more, e.g. the little Wren 44 putting out a bit more than the claimed 10lbs thrust, indicating that atmospheric conditions on the day were not disadvantageous. But the Wren Super Sport is recorded at 17lbs thrust compared to the 18lbs claimed. The reason this puzzles me is that Wren is very particular about making performance claims that everyone can expect to get, and not making claims based on one very good but rare engine. Is there an explanation why the Super Sport fielded by Wren themselves was not delivering 18lbs or 80N of claimed thrust?
Harry
I have a question about one of the results from the table posted by robrow. Many engines were delivering the manufacturer's claimed thrust or more, e.g. the little Wren 44 putting out a bit more than the claimed 10lbs thrust, indicating that atmospheric conditions on the day were not disadvantageous. But the Wren Super Sport is recorded at 17lbs thrust compared to the 18lbs claimed. The reason this puzzles me is that Wren is very particular about making performance claims that everyone can expect to get, and not making claims based on one very good but rare engine. Is there an explanation why the Super Sport fielded by Wren themselves was not delivering 18lbs or 80N of claimed thrust?
Harry
Hi Harry,
my Supersport is producing between 19-19.5lb depending on the day. Its fitted on the back of a bobcat. Awsome little engine.
jason
12-13-2006, 11:54 AM
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RE: I Feel Ripped Off
ORIGINAL: WrenTurbines
One is to make the tailcone smaller.
One is to make the tailcone smaller.
H.