Oh my, How nit picky we can get. I do thank you for
taking the time to read it!

Marc,
Perhaps I shouldn't be saying this as I have have just enjoyed two or three glasses of really excellent (Australian) wine, (Leeuwin Estate 1999 Chardonnay, world's best) , with dinner BUT my recent correspondence with Tam suggests he is less than sharp in a business sense ! Can explain, eloborate ! If he pulls his ads., that his right, it's his loss.

Regards,

David Gladwin.

Hi all,
This would be a good time for someone to put together a general handbook for building and operating Jet models (or similar). It should cover general recommendations for selection of servos , servo installation, linkages, hinging of control surfaces, mass balancing of control surfaces, power supply, antennas, (common practice) etc. It should also point out obvious risks etc. We could all review it here in this forum and give feed back to it until perfection . . . It should be written as a general guide book to benefit all in this forum incl manufacturers.
Would anyone like to take on this challenge ?

Kind Regards
/Johan Tinde

You are 100% right Dan. But you left out 2 things.... (1) TAM sold them the Skymaster F18 that had the "flaws"....and (2) Eric Wu replaced the plane even though he didnt sell it! Wonder if Tam will be replacing the Vipers?

Mike

Removed "OFF TOPIC"

No Bias Mike, READ what I wrote!
Just my personal experience with the aircraft in discussion. There may infact be issues with this airframe, that is what I plan to find out.... I gain nothing by performing this review beyond assuring you get a safe and relaible airframe! If anything, it is costing me both time and money....
Todd

Wao, what happened here this weekend?

People will alway find a way to talk for good or bad,,,,bud talks. And been sensitive about is
not a wise way to handle emotional intelligence.

A few of the critics expressed here are not well intentioned or constructive. Others are good.-At the end is balance.....

The bottom line....people talks. I talk. You talk. Is part of any business, even if for the majority of us is a hobby, others make living out of this,... out of us (including this forum). Is part of a show.

Can we change that? NO
Can we adapted to that? Yes, and play with it.-

Tam
IF in USA almost 50% voted against Bush....and he's there.......Then don't see a problem in having 50% of people voting against the Viper a/o your job, if you have the other half buying and supporting your product. Never everybody is happy...in this planet.

So, lets concentrate here in WHAT IS IMPORTANT. Let keep in the positive track sharing with the others really interested on the Viper, all the hints to build it right.

Unplug.....is not the answer.

If someone can explain my attachment in easier way ( Todd [sm=drowning.gif].....would be great [sm=thumbup.gif]
I'll take this to the original thread of Time to build my Viper....

O.K. guys, while all you MBA knobs were helping Tam run his business, we have been in the Viper II workshop......too cold to do anything else......

#1 Viper II has been completed with #2 & #3 well on their way......

I'll try to get pictures up starting tonite......final analysis before the maiden......well done kit...give it 8/10....a bit heavy......hinge design needs redesign, or at least detailed instructions on how to fix current production models......

Hope it flys as cool as it looks.....

Will be posting them over on Miguel's building thread if anyone is interested.....if not, carry on with Tam's On-Line Small Business Analysis.....

Tom

Hey Tom,

I've not seen the hinges on the Viper, but from what you are describing, it sounds as if the hinge protrusions you mention are done kinda like Matt showed us in http://www.rcuniverse.com/forum/fb.asp?m=762242 - is that correct ? Note the pics in posts 23, 24, 27, 28.

Gordon

Just aquick question here about the hinging on all the viperjet surfaces. I saw a kit recently and can agree that you will leave some portion of the hinge unsupported. I can honestly tell you that in my eurosport the rudder was the same way. It had an arm failure and fluttered like there was no tommorrow. The rudder never even came loose. Not to say that that is right that part of the hinge goes unsupported, but I built up the unsupported hinge with a little hysol before i attached the rudder, maybe that was what held it, I dont know. But my proposal is, and Im thinking about the hinge line on the viperjet, why not place a 1/8 or 1/4 piece of ply on top of all the holes that exist in the viperjet hinge line, and drill the holes again. Now you have built the hinge line out to the unsupported portion of the hinge, and now its supported. Can anyone see a potential problem with that? If not that should solve it.

Pete

Many moulded kits including Fiber Classics, Airworld and Skymaster that I have built have extended trailing edge surfaces on wings, tail plane and rudder its simply a matter of trimming a couple of millimeters from T.E. overhang to allow control surfaces to butt up against rear edge of wing etc. Its normal and common place and is part of building many composite kits now days.... Even on some older kits going back to Byron days this was the case ie Byron Mig 15

Gordon:

That is what we tried to do.....the only problem we encountered was no being able to properly shape the leading edge of the moveable surface as Matt did....we did not want to grind or sand into the fiberglass, not knowing for sure what was underneath......as it comes, with the very firm overhanging leading edge, almost firm like C/F, not the more flexible skin like on the Eurosport or Kingcat, the radius of the leading edges are too fat, and does not allow any travel.....

So we did build up the aft trailing edges with balsa to the proper depth which consumed a fair amout of time to get right and sanded, and holes relocated, since each surface is a little different, and in fact, each of our kits has a little different overhang, leading to a varying depth of the trailing edge......

Tom

Whoa! Big Fella! c/f, Slow down here. I was in Monterey and was without a computer. Please understand that as a Tamjets rep, I am not on payroll. Most reps in the industry start out as modelers and because of their exceptional skills at building/flying are invited by manufactures to help promote their products in return for a nominal discount on products. Remember, we are always modelers first and reps second. We spend our own hard earned money and time away from work & family to travel to jet events to fly our planes, assist other modelers, socialize with friends from different parts of the country, and otherwise have a great time doing the same thing that non-rep modelers do at an event. All of this is done without a single penny of reimbursement.

I am very fortunate that I earn a decent standard of living through my job and that I can participate in a great hobby like turbine r/c jets. However, having been on the "inside" during the last three years, I can tell you that the jet r/c industry is a very tough way to earn a living. The r/c jet market is very small and very competitive. Contrary to what many think, nobody is getting rich here. The turbine r/c market is living on a fine line. Continual pressures from a non-jet friendly AMA president, ever growning safety/fire liability concerns from non-friendly r/c clubs and flying sites, to competitive pricing pressure from overseas r/c companies, and it goes without saying that additional "bashing" on internet forums isn't make life any easier. As said before, the model jet community is very small where everybody knows everbody. Many of us who travel the country from jet meet to jet meet can attest that it is the "same thing, just a different location". And although the internet is a great forum to share information widely, the true work "in the trenches" is being done at the flying events, in-person and face to face. This is where product is promoted, sold, advised, etc., etc. Modelers can see with their own eyes what products work, which don't, and which ones are right for them.

Although I cannot comment without speculation on what the impact of "umplugging from RCU" will be on Tamjets, I can certainly understand Tam's decision. Tamjets had just completed a very successful promotional show at Florida Jets, which cost the company an enormous amount of money. To have all that time, money, and effort sabotaged by a few malicious individuals on the internet is a shame. If these individuals' intentions were anything but to solely try to defame an r/c company than they would make the effort to call Tamjets to get their r/c related question or concern answered. R/C jets are very technical and expensive machines, so I've always wondered why someone would leave to chance getting erroneous, unqualified, or hearsay information on these forums. Yes! these forums have been a great personal help to me and my hobby, but when it comes to putting a $10,000 jet in the air and the safety of the public is concerned, I have always confirmed this information by going straight to the manufacture direct.

In final, Tam has made a decision to no longer support RCU. As a Tamjets rep I am no longer authorized to use RCU on behalf of Tamjets. As a modeler, I will continue to use RCU on a non-rep basis in my other hobby endeavors, such as warbirds, electrics, and cars. All Tamjets questions should now be addressed directly at the Tamjets website or by phone.

Best wishes to all!

To date nobody has pointed me to a "bashing" of tamjets post that is in question here? Are these people saying that bringing up a problem is "bashing"? Are they saying that those who brought up a problem here literally made it up and that it has no merit? I would like somebody to clarify this for me and help me to understand.

Removed "OFF TOPIC"

One answer might be simply not to buy a kit that is designed in this fasion.

There are many Jet Kits out there that don't do it this way.

David

It is, perhaps, only fair that one such as yourself, endowed with such knowledge of full size aviation, technical matters pertaining to jet models and possessing clear communication skills should not also be as prescient in matters vinous.

Sir, I fear your third glass of Leeuwin Estate '99 has allowed euphoria to infect you with the same sense of brash certainty enjoyed by the denizens of your adopted homeland! It may well represent the finest efforts of that land of the "tinnie" but not, I am glad to say, the remainder of the civilised world.

As any gentleman knows the finest wine crafted from the chardonnay grape comes from Burgundy, France and is of course Le Montrachet
Domain Andre Remonet, a wine of unparalled celestial profoundness with the ability to make even strong men weep.

I shall, of course, forgive this temporary lapse in the normally reliable and excellent advice given to your avid readers, such as "hopper tanks for beginners" and other rivetting discourses.

In the meantime I remain your obedient servant and look forward to sipping, tasting and savouring your upcoming article in RC Jets on the beguiling Skymasters Hawk.

With kindest regards

John Agnew MW

Thanks for the clarification Tom. Please note that the following portion of this response is not directed specifically at you - but rather as a generic response to numerous contributors to this thread...

Given the above info - for the "unsupported" portion of the hinge to be a "major issue", wouldn't that now suggest that Matt's technique is totally wrong and unsafe, and we should now all have a go at Matt instead of Tam ?

Sorry Matt - I'm not claiming there's anything wrong with your technique - practically everyone knows that you know how to build a model that is absolutely solid - I'm just using this as an example of how the same technique seems to be able to get rave reviews or get crtiicized, depending on whose name is behind it.

Since this seems to be a rather subjective "issue" rather than an objective one, perhaps those who consider the standard hinge method of the Viper to be inadequate could simply add a "cone" of aeropoxy to spread the load and make it even less likely that the hinge would flex at its otherwise unsupported section. If that's the only kind of mod you need to address this particular issue then IMO some of the participants in this thread are blowing things WAY out of proportion to reality. I wish the ARFs that I've put together needed so little rework. Reworking the gearmounts alone, took over 8 hours on the last Roo I did for a friend !

Sounds to me like this whole subject is basically a case of various people making a mountain out of a mole-hill.

I have no doubt at all that Cermark could make further improvements to their Viper ; I have no doubt that such improvements WILL occur in future, just as they have occurred in the past when Tam & others did extensive testing on the original ARF and sent their feedback to Cermark. I also have no doubt that even if & when we get to a Mk 10 version of the aircraft, there will still be some minor issues (putting bug-fixes into software also tends to create some additonal bugs, so why would we expect that hardware would be any different).

Having a certain amount of issues in a kit or an ARF is simply a fact, and one that will not go away. Doesn't matter whose kit or ARF it is, I doubt that it can ever be 100% perfect in construction, and the manual will never answer every single question that can ever come up. Consumers and manufacturers alike need to recognize and understand that ; consumers need to understand that here are good ways to ask for info from manufacturers etc, and there are bad ways ; manufacturers / dealers / distributors need to likewise understand that there are good ways to respond to questions and / or criticism, and there are bad ways.

Now, maybe I'm just creating a mine-field for myself here by trying to find some kind of resolution, but sometimes it seems that that's where I feel most at home - so here goes...

My proposal to restore some form of normalcy here is as follows - Tam - keep your ad withdrawn (at least for now) if you feel that is the right thing to do, but don't simply withdraw all Tamjets presence here... that's just cutting your nose off to spite your face. Appoint John Orito as your "official spokesman" for any contentious issues (or as your sole RCU presence if you wish), and let him loose. From my past interaction with John, as well as from observing his past 'style" here on RCU I believe that he has the diplomatic skills that are frequently necessary here, the smarts and experience to ignore / deflect those posts that seem to be made simply to try to get a rise out of you, and the technical expertise to answer various questions on your product line. In short, I believe he can represent you extremely well while avoiding taking any of the bait that others may choose to set for him / you.

One of the things I value most about you Tam, is that you are absolutely straightforward and honest and you say exactly what you mean, as well as mean exactly what you say. Knowing that you'd never once even think of saying one thing to my face and another behind my back is great at the personal level, but unfortunately it is perhaps not always the best thing to do at the professional / business level where a certain amount of reserve and "marketing veneer" (aka BS layer) is expected to be applied in many / all communications. I know that you personally are too "genuine" to apply that BS layer, and I'm quite happy for you to stay that way - but think about having John handle that aspect for you. PS to John - don't take that as me saying you're full of BS - I think you know what I'm getting at here.

Tam / John - gimme a call if you think I can be of any assistance in helping straighten anything out. I'll PM you my home telephone number.

Spot - I believe you are misjudging Marc ; while I don't always agree 100% with everything he does or says, his heart is in the right place and there's usually a pretty good reason why he questioned people about commercial affiliations etc. I think that you too are perhaps over-reacting and doing him a disservice in the process.

Marc - two things:
(a) I don't think some of your comments in this thread should have been made here... I know you are simply trying to correct some impressions and / or explain what's going on, but when you make a fairly emotional post that can appear in any way to be pro- or anti- a given manufacturer / dealer etc, then there are plenty of people who will take that as "proof" that (i) this manufacturer is now officially a bad guy ; (ii) that its ok for them to jump in and have a go too. As RCU's top dog, you need (IMO) to stay out of the low-level fights as much as possible. Just as I feel Tam should refrain from answering some "provocative" posts (at all, or at least until after cooling down for an hour), I think you should too.. or just make a muted public response and take the stronger stuff to a private discussion.

(b) Regarding Dave (Strawboss) and his Artes affiliation ... I can't tell you exactly when Dave became a rep, or whether it was literally within 5 minutes of you previously asking him about it - but I can tell you for sure that it was very sudden. I know that one week he was lamenting how he wanted a (Jetcat) Titan but could not afford one, and the next week he told me he was a newly appointed Artes rep. If he had Artes plans the week before, I don't think even he would be dumb enuff to be ranting and raving about how he wanted a Jetcat Titan... but there again, we are talking about Dave

Marc - call me at home after 3:30 pm if you think it would help.

Later,
Gordon

Gordon,

Yes. I do see some of our points. I do hope that my posts did not indicate that I was endorsing or refuting any claims that were being made against Tamjets or his products. I do not have all the necessary information at my disposal to make that determination either way.

When these cases come up we rely on the companies to point out that a post is untrue, cannot be backed up and is damaging. In those cases we gather the evidence and we also defer to both the jet moderators and often a group of active jet modelers in here to confirm if the posts are factual or if they are false. If they are proven to be false we remove them. False statements and bad information help nobody. If the posts are true or likely to be true we will let them stand regardless of whether damaging to a company or not. The goal here is to get accurate info out and keep the false info off the site.

Next, some of the material I would have preferred to communicate in private but when certain issues or claims bubble up in these public threads towards RCU or me that are not true I do feel the need to address them in here because once somebody reads those posts then this thread is the only way to communicate to the masses what is true and what is not. If I took it all private many would be left with information I know to be false which is potentially damaging to RCU's reputation. I have in my possession all communications by all parties involved to backup everything I've stated here. I only want people to know the truth regarding what was said as it related to RCU.

The matter of Tam pulling the plug and the post that upset him which started this snowball is yet to be determined but my lines are all open if Tam or any of his reps want to supply us with additional information regarding which posts were made along with any backup information to show why the post(s) was/were not factual as Tam has stated.

What is difficult for me is that either me or one of the senior moderators here gets charged with playing judge and jury. None of us like being in that position. If you make a mistake and remove a post that might have been true you could risk loss from safety issues that could have been avoided. If you leave a post that is false you could damage a company from a post with no merits and also if bad advice somebody could get hurt.

Perhaps a board of advisors of 7-10 jet guys that everyone agrees on in here could be established to vote on "problem" posts and whether they should be removed when these problems should arise? That way any decisions are by way of a larger consensus of modelers in the thick of things. Since many feel that everyone has their bias here the panel would have to be a cross sectional representation of all vendors in some way. However this is something to discuss in another thread. I would like to keep this thread on the original topic and if a panel or something seems to be a good idea then we can pursue it in another thread.

FYI, I will say this sort of thing on all of RCU is a pretty rare occurrence in the scheme of things. Vendor complaints of false statements do happen but if I had to count them all up I'd say less than 20 or 30 per year max. It isn't a frequent occurrence. Half the time the reports are accurate and we pull the plug and the other half we keep them as they are substantiated.

Gordon:

This thread is moving into the blah blah blah blah zone......last post on this one for me.....

Matt did it right on the Stingray.....his hinges are well supported and geometry is perfect......no need to "have a go at Matt".....let him have quiet night with his wife......having Tam cross-threaded is enough....with all the crap on this thread, barely enough Heinekin in his liquor store to keep him from going postal......

As it comes from the factory, you cannot duplicate Matt's technique with ease on the Viper II.....so talking about it is a bit like apples and oranges, except to see what Matt's correct geometry looks like.....

The 3 of us who are building Viper II's have all recognized the problem and have fixed it to our satisfaction.....along with our HD linkage and 9411's I believe we are out of the flutter zone.......

A few photos of my buddy Dave's finished V II going on Miguel's build thread tonite.....

See ya all in the funnies....


T......

I agree, adding vertical gussets would make the exposed part of the hinge even stiffer, you can always improve!!. In my Stingray, I ended up with some pretty healthy fillets so I figured what the heck.

I have attached a couple of pics, see in the second one, I quit trying to make the clearance holes for the hinges on the movable piece, and just made the radius part in sections, so those slots in the elevator will clear the gussets.....Miguel did a great job of explaining the problem in post 58.

I agree with Tom, I would rather just cut this stuff out and do it myself...I spent more time trying to get the hinges to work on the Stinggray rudders, I think it has the same issue as the Viper, the taper was not right ....to me this will be hard to do on any ARF and is a little much to expect at the price, IMHO....you want those killer fits you almost have to do it yourself.

Having said that the only "ARF" I have seen that had predrilled, perfectly fitting hidden hinges is a Tom Cook Firebird, never seen anything close to the prefab and fit/finish on any arf.

Hi all,
I'm surpriced no one has gone in to detail about mass balancing the elevators and rudder. I have to say hello to Stahle from Norway who pointed this out at the beginning of this thread. We are both owners of the first batch of Viper Jet's. Stahle uses mini wing servos from Volz of about 4kg/cm and I am using Graupner 3728 digital wing servos with metal gears for elevators and rudder of similar torque (for elevator and rudders).
The key to success is the mass balancing. As the Viper control surfaces are quite nicely made for this to be done. If I remember correct I added ca 20g of lead in the leading edge of each elevator tip section (protruding in front of the hinge line). This weight resulted in a 100% static balance of the elevators. In the rudder top section (leading edge protruding in front of the hinge line) I put in as much as I could which was 30g resulting in approx 70% of static balance.
This is in total 50g of lead in the tail. I ended up with two receiver battery packs of 150g each in the nose cone and the ECU battery pack above the nose gear.
The new Super Viper is probably a bit heavier in the tail due to the added reinforcements so it may be undesirable to add all that weight in the tail after all. At least if you are installing standard size heavy servos.
The benefit of mass balancing is the drastic reduction of forces transferred to the drive train of the servo if a flutter is induced. And as a fact the tendency of self induced flutter is significantly reduced.
Regards/Johan

Unless the elevators venture into a torsional flutter mode. If the surface is near tuning up to a torsional mode, you could easily be in worse shape by counterbalancing. You could eliminate this possibility by mass balancing more evenly along the elevator, instead of just at the tips. Of course, this configuration does not lend itself to this.

Hello Johan!

Just a little correction reg. my elevator servos. They are 5 kg/cm or ~65 oz/in with metal gears. Very tight..

I do believe that the mass balancing of the elevators on MK1 Vipers combined with mechanically correct and tight servos/ linkages greatly reduces the risk of flutter. At least none of the planes I have heard of that have fluttered had done this.
I am no aerodynamics engineer, so I will not claim that it is the only and best thing to do, but it has been and still working for me and Johan. The elev's on my SM F15 and Eurosport canards are also balanced. Works fine!

Everything OK over there in Johan?
See you at a meeting this spring my friend! When is your first meeting in Sweden??