_Tommy D

My Feedback: (20)

Hey Guys... extreme speed or not, I was not sure where to ask about the VMAR line of prop jets. The search engine gave up some info on the Mig-21 but I was mostly wondering about the F-5. Has anyone built/flown it? Could someone kindly point me in the direction of a build thread?

Thanks!

Tommy D

crashgoodly

i just picked one up yesterday. i'll let you know how it goes. i can't find any build threads though.

_Tommy D

My Feedback: (20)

Wow...a Reply!

Thanks much... anything you can post.. with our without photos as you assemble it would be great.

How are you going to set it up?

Tommy D

crashgoodly

i know.... looks like we're it so far on this model. i've been searching everywhere for a build thread but can't find anything. i'm using an OS 75 max AX with an 14x8 prop. i'm flying it off a grass field so the 91 would make it heavy on the grass. i'm leaving it with fixed gear for now. i want to see how it flies before spending more.it's a very nice looking model and the covering looks fantastic. 7 hitec 325 carbonite servo's on the flight surfaces,and 1 futuba on the throttle. i'll put in arx battery that helps balance so i don't know what size yet. i've installed the tank and will put the motor in tomorrow. i'll post some pics later on. did you buy one? i bought mine on an impulse yesterday. it is something different and i've never seen one or heard of vmar until yesterday. i was looking fora new toy and it stood out over everything else i was looking at.

_Tommy D

My Feedback: (20)

No I did not buy one.

I like this one, and the Mig 21 for that matter as well.

Cash is very tight these days, so I watch the forum for a deal on a used one. Also hit the local swap meets and the likes.

Really looking forward to following along on your thread. I bet others are watching it as well.

Tommy D

crashgoodly

trying to load some pics program won't let me

SpeedBoy

I would love to see the report of this jet , of course pictures are always welcome .

btw , the OS 75 weights more than the 91. [X(]

pritz

I have been flying aVemar Mig-21 since July '06-Have 38 flites. Strengthen all u/c with carbon fiber and extra ribs in the wing and additional rails under the nose gear! My 21 has ST-G-90 with SA retracts Not too fast but impressive in the air. Most of my planes are Prop-Jets cheers Pritz

crashgoodly

the 75 weighs 19.4 ounces the 91 weighs 23.37 ounces .

crashgoodly

thanks i've been thinking that it needs strengthening. i'm going to resize my pics and try loading again i'm stuck without highspeed service in my area.

_Tommy D

My Feedback: (20)

Did you really cut the wings open and add extra ribs? I have to be reading something wrong there.

pritz

NO! I lay 1/4 to1/2in of carbon fiber inside the wing skins-then make a rib and C/A it BETWEEN the existing LG rail ribs. I have also duplicated the existing ribs (carbonfiber top and bottom) andC/A against these existing ribs like a sandwich. Alot of work; however I have not tore a L/G out of a wing on my Prop Jets-cracks-YES. My 8 yr. old Cermark F-16 HAD 274 flites BEFORE a mistake. Cheers Pritz

crashgoodly

just about finished but my antena wire broke so i got to go to the LHS. i'm planning to maiden thursday. the model went together with out any problems nose gears a little tight but it will wear in. still can't get any pics to upload.

airraptor

My Feedback: (66)

95 AX :
SPECS: Displacement: 0.949 cu in (15.55cc)
Bore: 1.091" (27.7mm)
Stroke: 1.016" (25.8mm)
Practical RPM: 2,000-16,000 RPM
Power Output: 2.9ps/15,000 RPM
Weight: Engine, 20oz (567g)
Muffler, 6.28oz (178g)



75 AX :
SPECS: Displacement: 0.75 cu in (12.3cc)
Bore: 1.02" (25.8mm)
Stroke: 0.93" (23.5mm)
Practical RPM: 2,000-16,000 RPM
Power Output: 2.4ps/15,000 RPM
Weight: 20.39 onuces (578g) w/o muffler
26.46 ounces (750g) w/ muffler
this direct from tower..... so the 95 really is lighter. run the jett muffler

crashgoodly

the 95 is, but not the 91. i have to rework the nose gear steering. the morons set it up at the factory so that the rudder and nose gear turn in different directions.i'm putting an extra servo in to run the nose gear. i'm also going to rework the the bulkhead were the nose gear mounts, it's not very strong.

SpeedBoy

Many sites says this .....

OS 91FX SPECIFICATIONS:
Displacement: 0.912 cu in (15.0cc)
Bore: 1.091 in (27.7mm)
Stroke: 0.976 in (24.8mm)
Practical RPM: 2,000-16,000
Output: 2.8 bhp (ps) @ 15,000 rpm
Weight: 19.3 oz (550g)
Includes: Muffler, Safety Propeller Locknut Assembly, #8 glow plug
Requires: fuel, mount & prop
Recommended Propellers: 13x8-9



O.S. 75 AX Specifications:
Displacement: 0.75 cu in (12.3cc)
Bore: 1.02" (25.8mm)
Stroke: 0.93" (23.5mm)
Practical RPM: 2,000-16,000 r.p.m.
Power Output: 2.4ps/15,000 r.p.m.
Weight: 20.39 onuces (578g) w/o muffler
26.46 ounces (750g) w/ muffler
Recommended Props: 14x6, 14x8, 15x7
Crankshaft thread size: 5/16-24
Distance from center of engine to drive hub: 2.62" (66.6mm)
Height from crankcase bottom to top of cylinder head: 4.07" (103.5mm)
Height/crankshaft center to top of cylinder head: 3.20" (81.5mm)
Width including mounting tabs: 2.4" (61mm)
Width not including mounting tabs: 1.67" (42.6mm)
Width between mounting holes same side: .98 (25mm)
Width between mounting holes opposite side: 2.04" (52mm)
Diameter of muffler body: 1.92" (48.8mm)
Angle of muffler in relation to engine: 4 degrees

crashgoodly

i got it right off the O.S. site. i'm done rebuilding the the nose gear set up. i put a servo just behind the nose gear and ran a solid wire link to the nose gear. it works great. i also put  ablock behind the nose gear bulk head and a ply deck for the servo and extra strength. i'll be maidening her tomorrow.  first gotta get the balance right though but that only takes a couple of minutes. all said and done it's an ok model, but the hump that they did with the rudder and nose gear setup makes me think that they never built anything but CAD models, or they are truly stupid as a boot.

crashgoodly

 it appears the OS 91 fx is discontinued.

_Tommy D

My Feedback: (20)

Great work Crash!

Any chance you can post up some photos so we can see your handy work?

crashgoodly

well she blew the nose and one main gear along with 70% of the unedrside of that wing side just  rolling up to take off speed. the balsa is pure garbage. this was her maiden 50 feet and she crumbled like thin paper.

_Tommy D

My Feedback: (20)

Holy @#$%^!!

Are you going to contact V-Mar or is that a lost cause.

That really sucks.

crashgoodly

i tried to contact them but thats a lot harder then it's worth. i'm going to rework all the gear mounts and strenghten everything the model is buy no means a loss it just needs to be done right. there was no support for the mains other then two small balsa ribs that reach only an inch either direction of the mains. truly a poor design but again fixable. i bought it off hobby hobby and they realy slaezed out with their support so lesson learned as to where my hobby dollars go. i still realy like the looks of this model so doing it right is a must. i'll keep posting and will keep trying to load some pics. it takes so long with dial up that it keeps running out of time and doesn't load. i'm off to the LHS tomorrow to pick up wood and carbon fibre to build proper gear mounts. she will fly, just later then i hoped. it is also a lesson in being lazy and not reinforcing an ARF like i normaly would do before flying it. it's just that it was getting late in the season and i wanted to put it up before the weather gets nasty.

kmtranmd

My Feedback: (71)

Thanks for sharing your experience with VMAR product. I always wondered why they are not popular. I considered getting the Mig 21 at one point. But I'll stick with my proven Cermark F16 airframe.

NoFlaps

My Feedback: (131)

Dude,
I'm sorry I didn't see this thread earlier...I would have warned you about the cheap wood/ gear mounts.
I have/has the A4. Maiden flight TO roll from our paved runway I clipped the (short) grass as she lifted, and it pulled my retracts right out! Plane flew very nicely with the OS55ax but dangling gear caused some drag. The greased in belly landing looked something like the intro of the six million dollar man TV show...the wood is soo flimsy & brittle that the thing turned into toothpics.

_Tommy D

My Feedback: (20)

crashgoodly ... any updates?