RE: JetJoe OWNERS thread
[quote]ORIGINAL: dynopower ... Theres nothing intrinsically wrong with the jet joe motors or their parts... [/quote] There is! Bad metallurgy and bad tolerances to name just two. These are not things that are "fixable" by the average modeler.
Posted on: 11/20/2009 2:27 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9267788

RE: How to balance the turbine?
[quote]ORIGINAL: Jetbono So Do you advise me to cancel this order ? [/quote] That's up to you to decide. Your chances of balancing anything with that contraption is nil. Just out of curiosity, why do you need to balance a turbine?
Posted on: 11/20/2009 1:06 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9267719

RE: Jetjoe 3000 turbine
[quote]ORIGINAL: andy boy     .... P.S- oh yea i almost forget to ask 1 last question i see balancer on website(no price just balancer) now i am not trying to play jet engine mechanic(far from it) but i might want to dissasemble engine and learn how to use balancer is it somthing beginer could use??? [/quote] The balancer is crap... Just like the engine. You really don't need a balancer to take the engine apart and put it back together. You do need to mark the position of the compressor relative to the shaft and the turbine. Balancing is more complicated than just putting it on the machine and spinning. Not impossible but beyond the scope of a single post. If you really want to understand jet engines I suggest you join the GTBA ([link]http://www.gtba.co.uk[/link]). There's a great deal of information there.
Posted on: 11/19/2009 1:50 AM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9264474

RE: Turbine tear down
[quote]ORIGINAL: DelGatoGrande [quote]ORIGINAL: frema .., but he forgot something to show, he had put marks on the turbine wheel and compressor before he tear it down. [/quote] i agree.when he removed the main bolt he should mark the axle to the compressor or even bolt to compressor! .now he dont know where the original ballanced point was! also the rear bearing should be a thrust type one (45 degrees) or even only balls but again used for thrust force if im not mistaken that looks like a normal axle one..[&o] [/quote] They are angular contact hybrid ceramic ball bearings. They look like normal ball bearings but they are designed to operate with a side force. They feel very loose when they are without preload and they fall apart readily if pushed in the wrong direction.
Posted on: 11/13/2009 1:19 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9251143

RE: How to balance the turbine?
[quote]ORIGINAL: fabionet31 Hi, i need a balancing machine to balance the turbine. But i see any machine in the web for example http://www.jetjoe.com/cp_detail.php?id=10188&nowmenuid=7174&cpath=&catid=0 or this http://www.technologie-entwicklung.de/Gasturbines/Balancing_Tool/balancing_tool.html But my friends in Italy advised to me to NOT BUY THIS!!! because not work!! can help me? [/quote] If you're doing just one turbine don't mess around with balancers. The rocking method is perfectly satisfactory for up to 160krpm. It's not just a balancing machine. You also need to understand how to balance. It's not too difficult but it does take some learning. Again, if it's only one turbine then don't bother.
Posted on: 11/4/2009 12:00 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9227657

RE: King's K70x owner thread
I'm coming around to like these engines. It looks like someone sat long and thought hard how to produce an engine which costs as little as possible while still being safe and reliable. I think they did a really good job! The diffuser looks like it's cast. They eliminated the fuel ring by using "J" sticks. They eliminated every thing that hinders speedy manufacturing. Even the chamfers on the shaft :) The result? A low cost turbine that actually works. Again, very well done! But where's the catch (some might ask). The catch is in efficiency. The fuel draw is high and it's also the cause of the smoke. This doesn't mean it's a bad engine. That's just it's limitation.
Posted on: 10/25/2009 4:05 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9201029

RE: Jetjoe 3000 turbine
[quote]ORIGINAL: BJ64 Erazz - I'm not trying to sell anything. ... Bugger-off back into your own threads, and stop being killjoys to those of us who have found a viable way to get into the marvellous world of Turbines. [/quote] You sure sound as though you're selling JJ.
Posted on: 10/17/2009 5:43 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9180972

RE: Jetjoe 3000 turbine
[quote]ORIGINAL: BJ64 ahem....''allegedly'' plagiarism... Probably not the best choice of words - plagiarism - that's usually reserved for literature. I think what you mean is 'patent infringement' Have any of these things been 'patented? If so, there are powerful laws there to protect the rightful patent owner. It's up to the rightful patent holder to persue these. If not, then it's open slather. Now, take for poor old Frank Whittle for example. The patent renewal fee of 5 Pounds in 1935 was beyond his means. The British Air Ministry refused to pay on his behalf, so his patent sadly lapsed. Not that that would have made one iota of differnce in war-time anyways... BJ:) [/quote] Plagiarism is applicable here as well. Intellectual property can be stolen even if it's not patented. And yes, in most countries you can actually sue for this. As for the "allegedly" part... I guess it's just a coincidence that his engines are exact copies (down to the last part and dimension) of other engines [8|] Read the "thief" part of my post. We're not going to like him because he's a thief. The part I really don't get is why you feel such an urge to defend him.
Posted on: 10/17/2009 4:16 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9180802

RE: Jetjoe 3000 turbine
[quote]ORIGINAL: BJ64 Perhaps you should ask JetJoe that one, Siclick. And when I finally have my machines all together, perhaps I just will. [/quote] Hmmmm.... You really should. (Build an engine that is) I'm trying to do that now and I must tell you it's a lot more difficult than you think. And if you think there's no R&D involved then again, you're just showing ignorance. Kero start, transonic compressors and low solidity diffusers are just some of the things that are very new. Please understand that the negativity is not directed at you but rather at JJ. He actively ripped off the people who made these turbines possible. You say that JJ is the reason you can get into turbines? I say JJ is keeping the turbine world from moving forward. People are more concerned that he'll rip them off rather than develop further. Wren, for example used to share information freely (they helped me a lot). They now have to hide everything they do or they'll be out of business. That's why by actively promoting JJ you piss people off. It's like walking around your street with a thief who robed your neighbours while telling them he's really a great guy. Kinda hard to swallow. You're very welcome here and you're very welcome to share your experience with your engine. If it's a good experience then that's all the better! But please don't try to sell us those engines. We've seen them.
Posted on: 10/17/2009 3:54 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9180768

RE: JetJoe OWNERS thread
[quote]ORIGINAL: Xairflyer The NGV were is the past Stainless but I believe now they are inconel Is this method of balancing any better [/quote] Yes. The ring is there especially for balancing. It does not provide any strength and therefore does not weaken the turbine when ground away. [quote]ORIGINAL: HKruisman Both ways are good enough. Mine has the same balancing marks. [/quote] Absolutely not!!! One method severely compromises the structural integrity of the turbine. There's a saying in Hebrew that translates roughly into "A successful folly does not wisdom make".
Posted on: 10/10/2009 4:21 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9162050

RE: JetJoe OWNERS thread
[quote]ORIGINAL: Boomerang1 Erazz, I'm not a JJ owner but what are you saying? I should imagine most turbine wheels are not perfectly balanced out of the mould & would have to be balanced by grinding part of the wheel away. It would be up to the manufacturer to decide which wheels need too much ground away, which would affect the integrity of the wheel, to achieve balance & therefore
Posted on: 10/9/2009 10:38 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9160720

RE: JetJoe OWNERS thread
I'm sorry, these just make me cringe! I would not stand next to that turbine while running.
Posted on: 10/9/2009 6:36 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9160117

RE: JetJoe OWNERS thread
[quote]ORIGINAL: Xairflyer From my simple strip down and learning curve about this turbine, I can’t understand why there has been so many problems.... [/quote] As you said, you don't have knowledge in gas turbines. They are very deceptive. The shaft tunnel for example. Looks fairly easy to make and it really isn't all that hard. You do, however, have to make sure that the faces are as concentric and parallel as possible. Get this wrong by 2-3 microns and the bearings might wear prematurely or even the turbine might not run at all. Looking at the pictures it seems that the holes in the rear of the diffuser which are designed to let cooling air through to the bearings are blocked. In the original Wren there was a fine mesh screen there. This could lead to insufficient lubrication and bearing failure. (hmmm.... do a lot of JJ's have bearing issues? [8|]) There are other things that you can't see that may be of importance. For example the turbine is cast from Inconel 713c. At least it's supposed to be cast from Inconel 713c. The casting process is difficult and expensive. It's easy to use a different casting process that produces a different grade of Inconel. This reduces the already low margin of safety for these turbines. Some turbine mfg's x-ray their turbines to make sure that they don't explode on you. A failed test means that the whole batch of turbines is scrapped. *Expensive* (Ever wonder how JJ can produce low cost turbines? [8|]) These are only a few issues that can be problematic. My point is that JJ's are inferior motors made to sub par specifications with little or no understanding of the real issues faced by turbines. The user pays for these with problems, lesser performance and reduced safety. p.s. I have seen claims that the JJ turbines are x-rayed. Coming from a mfg with a history of copying and cutting corners I take these claims with more than a grain of salt.
Posted on: 10/7/2009 11:57 AM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9153863

RE: Zoom Zoom Zoom Fast...
[:D] I bet it goes only 199.999999mph Do you have any info on the kit? p.s. Pleeeseee keep the fingers away from the turbine on startup. I know of at least one person that lost his pinkie like that!
Posted on: 9/5/2009 2:28 AM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9071095

RE: Mixing larger amounts of resin
You either keep on mixing small amounts (not really good) or you make sure you apply all of the resin really fast. When it's spread out thin it doesn't take off like when it's in a pot. For REALLY large projects there are resins that take longer to harder or that require an external heat source.
Posted on: 9/3/2009 3:31 AM by Author "erazz" in the forum "Composites Fabrication And Repair"
http://www.rcuniverse.com/forum/fb.asp?m=9066271

RE: When glassing your wings (if you still do), what resin do you use?
I use a different brand but W-System is vastly superior to Z-Poxy IMHO. Z-Poxy is great for small things.
Posted on: 9/3/2009 3:22 AM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9066265

RE: F-18 wing twist
[quote]ORIGINAL: bela It isnt the airfoil Naca sections Im asking about. It is the twist of the wing of the real aircraft. In certain books It is quoted as being zero degree washout, yet when viewed from the side, the wingtip has an obvious extreme negative AOA. if measured, this AoA seems beyond the sometimes quoted 4 degrees for the wing. Does anyone have access to an early enough Janes aircraft book, that would still have the f-18C wing specs? [/quote] I'll say it again. The washout changes in flight. On the ground you might see a lot of washout but S&L you would see no washout. I believe that as the G rises you would see washout increase again. This means that washout on the ground is both irrelevant and coincidental. You can't find the number because no one probably measured it.
Posted on: 8/24/2009 3:52 AM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9039684

RE: F-18 wing twist
[quote]ORIGINAL: bela Im having problems getting the numbers to the wing of the f-18C. I have alot of conflicting sources and wont be able to consult the library for a couple of weeks. I have a Janes aircraft book, but it is 2005 version, which only gives the numbers for the superhornet. In particular, Im trying to get the washout numbers. Ive read that the wing has zero washout but the wingtip launcher is mounted with negative aoa to counter the f-18 nose high flight tendency. Another source says the wing has 4 degree of twist. most sources Ive read claim 3 degrees annhedral. Each time Ive been around an f-18, Im always locked on the landing gear and slotted double flap setup and always forget to look at the wing twist. Anyone know the true numbers? Thanx in advance. [/quote] AFAIK the actual washout changes during flight. The F-18's wing is designed to flex and change during flight to reduce loads and allow a lighter structure. Either way, if you're planing on making a flying model based on the real wing - don't. You'll end up with a poor flying model. I'd use a thin NACA airfoil with no more than 1deg of washout.
Posted on: 8/23/2009 2:47 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9038092

RE: post your jet plane photos here
Not nearly as nice as the other airplanes here... but still [:D]
Posted on: 8/21/2009 2:06 AM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=9032816

RE: A123 - RX TO JETS
I've also been using A123's on my planes. You don't need regulators since a freshly charged 5 cell Nicd has a higher voltage. Fast to charge and very robust. Highly recommended. The only concern is the voltage drop on load especially with a high count of digital servos. The best setup would be to parallel 2 packs through 2 switches. For extremely high drains the best option is still Nicads.
Posted on: 8/30/2008 1:21 AM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=7901124

RE: Is glass cloth needed for finishing floats?
I don't want to cross-post and/or hijack this thread... Here's the details: [link=http://www.rcuniverse.com/forum/fb.asp?m=7825930]http://www.rcuniverse.com/forum/fb.asp?m=7825930[/link]
Posted on: 8/15/2008 2:59 AM by Author "erazz" in the forum "Seaplanes"
http://www.rcuniverse.com/forum/fb.asp?m=7847922

RE: Kingtech Jets
[quote]ORIGINAL: CPS As I have seen in the test flight by installing on the Skymaster F-16,it is very powerful engine.As I know,this engine is a brand new turbine engine.Most parts are new designed by the builder,not copy from other engines.(the builder cooperated with university turbine engine professor)Only the ECU use FADEC ,not self-design,easy to set and programming. Most important,the builder hope to promote this hobby by lower price! [/quote] Oh Pleeaaaassseee. I'm designing an engine and I'm consulting with a university professor which happens to specialize in miniature turbojet engines. Do you think he knows the exact details of c.c. design for the engine? Sure he knows the theory but there's still a gap between theory and practice (engineering). In the end it takes a lot of iterations to produce a working engine. They don't just "pop out" from the blue. As far as I see there are couple of things wrong here: 1) Far east mfg. We've been burned before, we're more cautious now. 2) No history. 3) No proper website 4) A multitude of "reccomenders" who have just joined RCU and are already praising the engine as the bees knees. 5) No "real" information on the engine. Test data? Facility data? In short, this whole deal looks fishy to me. I'd bet we'll soon see pictures of the "production facility" and all sorts of data on the engine. At this point I'd take anything that's coming from there with a lot of skepticism. Point is that to make a quality engine you need to be in the business and not just posts rave reviews on RCU. I feel better now... Can get off my soapbox. [:D]
Posted on: 8/14/2008 11:41 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=7847557

RE: Is glass cloth needed for finishing floats?
I prefer not to glass.... I sheet with balsa and cover with an adhesive backed plastic. This plastic is used in graphic design and it sticks very well. The advantage is that it's relatively thick and flexible. This makes it very puncture proof. It weighs the same a a thin layer of fiberglass and it's much much easier to use. [:D] Glass, in my experience is brittle. So it tends to puncture and break while going over rocks. Here's my ride... And it uses this plastic film.
Posted on: 8/14/2008 2:04 AM by Author "erazz" in the forum "Seaplanes"
http://www.rcuniverse.com/forum/fb.asp?m=7844031

RE: Old Nicad/ Nimh batteries
Still using Nicads alongside A123's. For performance you can't beat a Nicad!
Posted on: 8/12/2008 2:32 AM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=7836171

RE: ATJ Turbines
I would ask where are the turbine wheels made? By whom? Are they x-rayed? Can we get a certificate? Some things may look hunky-dory but may be very wrong in essence. It's just so easy to produce good "looking" engines these days. It's not until you fire one up that you see what you got. I'd rather spend my money on a name I can trust.
Posted on: 8/10/2008 4:11 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=7830325

RE: Kingtech Jets
[quote]ORIGINAL: Strykaas At least with these low RPM big turbine engines, the probability of throwing blades because of faulty chinese casting is reduced to some extent [8|]. [/quote] Don't be so sure. The stresses are comparable. They are just as likely to throw a blade and more likely to do damage when they do. But hey... It sure makes things interesting!
Posted on: 8/10/2008 9:54 AM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=7829390

RE: Bob Cat Copy Falcon 120 Jet
Did I say no vid?? I meant no vid [u]yet[/u]! [link=http://www.youtube.com/watch?v=YAS6q9dwHxE]http://www.youtube.com/watch?v=YAS6q9dwHxE[/link] (yes I know it's not good quality but in the absence of a pro cameraman I'll take what I can get)
Posted on: 8/9/2008 1:49 PM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=7826950

RE: Bob Cat Copy Falcon 120 Jet
Hi Guys and thanks for the compliments... I'd like to thank Ravivos for the excellent pictures. There was no inspiration other than the severe lack of runway at my local field. I must admit that being able to cool-off between flights is a very big plus. 35 degrees C + 90% humidity is hot! But returning the plane is both fun and a good exercise [:D] When I started the conversion I thought about leaving an option for the landing gear. I've since removed and taped over all the bays. This one is a keeper as a float plane. Sorry but I'm not the kit producing person. I'd be happy to share the design and lessons learned with anyone who wishes to.
Posted on: 8/9/2008 11:10 AM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=7826612

RE: Bob Cat Copy Falcon 120 Jet
And her's some of mine from this Friday Sorry, no video yet [:o]
Posted on: 8/9/2008 1:14 AM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=7825930

RE: Burn Ban-Texas
Burn-Ban.... Lake..... [sm=50_50.gif]
Posted on: 8/5/2008 5:43 AM by Author "erazz" in the forum "RC Jets"
http://www.rcuniverse.com/forum/fb.asp?m=7810288