HI GUY!

What a viofan with a os 91 product for thrust in pound please?Or is a better fan on a market?

thank you guy!

The Viojet unit with O.S. 91 is about 12 pounds.
With Viofan, not sure if you can use O.S. with that, if so I would say thrust would be about 1/2 pound to a pound more?

VIOFAN is one or maybe the most efficient DF unit at he moment. Just the have a !QUOT!special condition!QUOT! in my opinion and what I could see around.
1-If you have a BVM engine like their 96 which Nelson make special for them (I think) so you can have 12+Lb of thrust.With an OS besides is a very reliable engine, it doesn develop same HP/torque as the BVM engine, so don't expect same thrust.
2-VIOFAN works with the !QUOT!rule area!QUOT! so you must have their intake and exhaust duct if you want take all the advantages of the unit.
3-If you don't plan to install this unit in one of their airplanes,you will have a long list of problems to solve unless someone will tells you what to do exactly.Due VIOFAN is very sensitive for the intake.More sensitive than RAMTEC and DYNAMAX.
4-If you are far away from the above conditions, go to JMP and you can buy the DYNAMAX which will work perfect with your OS, plus the have a matching pipe and all hardware at better price.

Remember that I`m not telling that one is better than other, just every unit and engine works better with a particular combination.
The VIOFAN is a typical I call MATCHING SYSTEM, this unit works great with their airplanes like F-86 was designed around.
I never saw a VIOFAN working properly outside one of their airplanes nor one of their airplane performing perfect with a VIOFAN and an OS. An example was one of my pals, he didn't want to pay 300$ more for a BVM matching system(engine with all ascesories) and he bougth an OS 91, his airplane fly, but all time at limit until he makes the mistake and lost all investment¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡
Other paid the extras and fly his bird for almost 2 years and rebuild egine by BVM once until he decide to change to turbines, he rebult engine again and sold it. He got the conversion kit from BVM and now his bird is going turbine.

So,be clear of what you want, if you wanna go fast you have to insure your investment, if not. go to the usual and get out of troubles, go to a proven universal matching sistem.

David P.

I have heard similar before. Dynamax mates well with OS, Viojett mates well with BVM. Mix and match may end in disaster. I would go too with the proven performance. OS will not have any problem spining a Dynamax, where a BVM may overheat because of the extra load (from having more blades I think). On the other hand, an OS will burnout with a Viojett because it is not designed for sustained high RPM like the BVM.

I think Bob Violett himself spoke with the developer of Dynamax and OS engines so that it would work out that way.

David

Are you kidding, the BVM will not overheat with a Dynamax setup.
I had it on a Y/A F-16A & it performed flawless.

David: you are almost rigth¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡ all is a question of mix-match rigth combination

The problem is not the fan units, the problem is the following: DYNAMAX was one of the first true effective tractor DF unit and they work well due was designed around available engines at the moment and basically the OS. The OS runs happy and safe if you don't run above 21000 rpms, he can go more but you will be working in the red line and 22000 rpms is almost sure you will break rod at any moment. Instead, if you use a Rossi 90 with a Dynamax, you dont have to run more than half throttle or max 3/4, due HP/torque of bot engines are different.Rossi can go higher than OS without problems and also last more than double of OS engine but you need to know how to deal with a Rossi or you are dead bird, BVM engine is not easy but easier than Rossi and a bunch of power also.
Going with DF units, this is not a matter of blades but a matter of pitch. Example: Dynamax cant absorb Rossi 90 WOT for long periods, something will break if you don't put attention(above example) due the DYNAMAX have 11 blades and low pitch, has a lot of static trust wich make easier for landings and take-off, RAMTEC has 9 blades but higher trust,VIOFAN has I think 7 blades and high pitch.So here comparing three units you are going from the hig static trust (Dynamax) to the highest dynamic trust(VIOFAN) RAMTEC is in the middle and is one of the reason why you need a lot of distance for take of and landings with VIOFAN but also is the fastest DF unit. I explained this in an easyest way and without formulas and also with my basic English, but is similar principle when you change props at your airplane from two to three to four, you gains something but you loose also something. In my opinion OS will not overheat with VIOFAN for overev, but I think(you didn't give details) one main reason is the pipe, OS doest like small pipes(they will built more HP but heat increase easy) JMP has the right one, if you use some different pipe or combination you have to play and find the rigth combination(is your time and your money) but also what you said for heavy load on engine could be true but not for more blades but for the pitch.Engine is under heavy load ant low rpms no air flowing around for cooling and also you are not able to change timing and engine is not working at the desiderable powerband range plus a lot ot other involved variables like fuel(hig nitro with low rpms and high load means HEAT if you dont have the rigth glowplug.)

I personaly I`m building a TRIMAIR F-86 and have the RAMTEC unit recommended for the kit. It comes with their own inlet and outlet matching duct-sistem.I asked for some details and they said: It works perfect with OS 91 with the right pipe,if you install a Rossi and know how to deal with them it will fly much faster due it runs higger rpm, if you use Dynamax or Viofan, go to Dynamax due the special conditions required for Viofan.

My airplane is not ready yet but I build a test bench for my engines and combination due I have a lot of Rossi 90 I ordered Rossi mount and what the said was true, I tested Rossi with different pipes and pipes lengths and also with OS 91, with OS is works really smoot but doesnt develope as high rpms as Rossi and will built heta as rpms increase with small pipes.(small pipes compresed more the engines)

FLYTICOUN, remember if you want to go to RAMTEC you need a bigger intake area than a Dynamax, if you still wanting VIOFAN, find the rigth designed inlet and outlet ducts if you want to obtain true trust-rpm combination. Dynamax can be re-pitch from people offering the service(you can find here in the forums) or installing a RAMTEC rotor in a Dynamax(I don't know details but know people did)

So, let me get this straight, A BVM .91 should not overheat in a Dynamax?

I was getting ready to purchase an OS 91 for my Y/A F-16 with a Dynamax, because I heard that anything different than an OS would give me problems (on a Dynamax). I currently fly a BVM F-16 with the BVM .91 and Viofan and it is just awesome. I've never needed to reset the carburator, just the glow plugs every 4-5 flights.

David

David,

I have never heard anyone report that a BVM 91 overheated in a Dynamax. However, over the years there have been reports that the BVM engine(s) "were never happy" in a Dynamax/Ramtec fan. The BVM engines tend to perform best at the higher rpms that are possible in the Viojet/Viofan. That's really what separates the BVM engine from an OS...ability to opearate at sustained rpm levels around 24k.

Peter

HOLD ON HOLD ON[X(] PETER I´m not saying that[X(]¡ maybe my leak of perfect english could make a confusion.Were did I write that affirmation?

BVM engine 91 or 96 will not overheat and I don't have personal experience due I don't own one but I help my friends at the field.
The problem with BVM engines is not realy a problem, is just too much engine for a DYNAMAX unit.
BVM 91 or 96 will over-rev in a DYNAMX easily,same for Rossi 90 with DYNAMAX.
You can use but you cant sustain WOT due DYNAMAX will not absorb all HP produced with bot engines, specially the BVM.
OS runs happy in 21000 rpms and make power at lower rpm than Rossi or BVM.
Rossi runs happy in 22000-23000 depending of which model of 90 are you using.
BVM 91 or 96 can sustain the 24000 K like Peter said.And they perform well because the unit was designed for their engines, remember the rule area.

As I told in previous posts, you can use a stronger engine in a DYNAMAX but you just will overev either one the Rossi or the BVM.
Personally I set a Dynamax unit for a friend with a Rossi 90 older model(shor rodIt hink is the 49R90 were carb goes out with two screws) and he never runs more than 3/4 of throttle but not sustained, but 1/2 constant and airplane flyes perfect. We try WOT in the bench, engine scream incredible but it will not stay together not the engine but DF unit, so in order to keep control we decide to use a bigger pipe in order to control max rpms and decompress the engine with extra shims.

On the other side in my personal opinion, it doesn make sense a person to buy a BVM 91 or 96 to install in a DYNAMAX. MAkes more sense to use a Rossi 90 or 105 in a VIOFAN but either way is not a RIGHT MATCH COMBINATION.

Falcon, go with OS an DYNAMAX and you will be in the right path.Remember to include in your order all pipe and header system,remote needle and pressurized pitot tube.

Edited: Nevermind, got confused in Davids.

I will do so. Thanks David and Peter.

Thunder8A36, it appears that you have misinterpreted my posting. I was responding to FalconWings' question(s), not your posting.

Also, do you have data that proves that the BVM engine will "over-rev" in a Dynamax?
Last I heard, the max HP output of the BVM 91 was equivalent to that of the OS 9.1 per the engine performance test carried out by Mike Billington in the UK several years ago (published in RCJI as I recall). The BIG difference between the two was that the BVM engine could survive the sustained higher rpms associated with operating in a Viojett. The OS 91 will also turn 24k in a Viojet, but not for very long....

Peter

An OS.91 will turn more than 21000 in a Byron Fan. In a Dynamax I've seen almost 24000 on the ground and it unloads some in the air. I've owned a dozen or so OS.91s and I've flown them hundreds of flights and I've never broken a rod. I've always used 5% fuel and the for the last 5 years I have used either Wildcat Jet-A or PowerMaster ducted fan fuel. I have seen the OS.91/Dynamax fan combo fly a 30# T-33 with authority.

Hi,

I don't know how one mounts an O.S. .91 into a Viofan, but in a Viojett fan, the O.S. .91 performed VERY well. I had heard over the years (mostly from people who'd never actually tried it) that the combo was dangerous and certain to fail. After talking with BV, I felt better about trying it myself. It worked great.

OK, I may be confused here: Viofan is BVM, while Viojett is Byron, right?

Falcon Wings,
Viofan is BVM. Viojett is BVM. NEITHER ONE has ANYTHING to do with Byron at all. Go to www.bvmjets.com. Click assessories. Check it out for yourself.

Hope this helps.

Jackjet

Never ceases to amaze me when people spend thousands of $$ to get a D/F in the air and skimp on the most critical component.

JMHO, but if you're using a Viojet or a Viofan why in God's name don't you just get an engine from BVM as well? These components are designed to work together, while all the other combinations you're considering are not. They are compromises.

Don't compromise.

I agree. I have two Viojetts with BVM .91's and they don't miss heartbeat.

BVMJethead,


What you're saying makes sense. I am not advising him to go buy an O.S. .91 for his Violett fan. My thought from reading his post was that he already had that setup. I would hate to see anyone be in the situation I was in some years ago when a few people (none of whom knew first hand, it turned out) told me that I'd be skimping to the detriment of my airplane if I used that combo. At that time, RCO wasn't around yet, but the jet page of the Model Aviation Special Interest Group gave the same advice; 'Don't do it, you'll be sorry....' Finally, I called BV and he told me that it was all BULL****E. He said that the BV engine is better and will put out more thrust and last longer, but that the O.S. worked fine in his fan. His advice, while contrary to that of some of the folks in here, saved me quite a lot of worry--and a few hundred bucks, too. In the end, the combo worked superbly for about 82 flights--the airplane was faster with that combo than with the .96SE (in fairness, the .96 was quite a bit older) Then I sold it. Did I comprimise? Maybe..... Would I do it again? Yep!

YellowAircraft and bvmjethead:

Both of you have a good and true point. I`m just sharing my experiences and what I have.
Regarding a VIOFAN it is an excellent choice but must go with BVM engine ( my opinion) not with OS 91 either way could work, period.
About testing I made at home in my bench, it was just for fun and have a comparison point.
I have a RAMTEC that works great with a Rossi 90 and also I set up for a couple of customers DYNAMAX one with an OS91 and JMP pipe and another with a Rossi 90 modified, and bot are performing well.

Again an in deferents words and with my elemental english, if You have a Ferrari I assume you will have a Ferrari engine ( VIOFAN AND BVM engine) if you have a Porsche you should use a Porsche engine(Dynamax with OS or Ramtec with OS or Rossi 90)
Maybe you can use a Porsche engine in a Ferrari or vice versa and maybe will work for a period of time.But something will happen at any moment plus all involved in trying to swap parts correctly.

I`m not an expert like some of you guys and think this kind of post are all time useful.Most of the time new people is coming here at RCU to learn. Is like a school. I personally learned a lot during last year just reading posts and helping others setting their DF before having my own.

Miragepilot: I don't have data that proves BVM engine will over-rev but if Rossi does, BVM egine will do much easier. I promess will try and will let you know.

David P.