RE: VMAR Mig 21
 

Looks great, nice job, my favorite Rooski fighter.

Chuck

RE: VMAR Mig 21
 

Thanks for the pics and flight report Doc. I've been waiting for those for a long time! I have to admit I've always liked the Mig-21, and now I think this is one of the coolest ARFs I've ever seen.

Tom

RE: VMAR Mig 21
 

2 questions: 1. Would you still recommend going with a .91 2-stroke versus the .60, and 2. is the cowl pre-cut for the head and muffler? If the cowl is pre-cut, then I don't see much reason to go with electric.

RE: VMAR Mig 21
 

Tom,
At first I really contemplated removing my .60 and putting in a .90, but yesterday convinced me that I would be happy with the perfomrance as it is. A .60 is plenty of power if you do not horse it off the ground and allow it to build up speed before you start yanking and banking it. Also the aileron throw does not need to be much (no more than 3/8 on the low rates, and use exponential). It is very sensitive to the ailerons at high speed. The plane flies with the nose high, and I know mine is not tail heavy, even at high speed the nose looks a little high. It is very stable. As you can see in the pics of the low passes, I was holding this thing a foot off of the runway and she never bobbled. The tail continues to slide around in the turns, but I believe this to be due to the fact that the original airframe did not have propwash against that big vertical stab.
I lost one of my rocket pods in flight, my fault, and there was no noticeable difference in flight characteristics. If you have a 90, use it, but if you have a good trusty 60, it will adequate.
I cannot tell you if the cowl was precut. When I bought this plane it had been started and my cowl was cut, I do not know if that is the case right out of the box. It would make a fine electric airplane, no doubt.
Right now, I refuse to do anything else to mine, if it works I am going to leave it alone, and this thing is fun to fly so I am thru trying to make it better. It lands very nicely, no bouncing, and the steering is adequate. At low speed, with the flaps deployed, she does not appear to have any snappy stall characteristics. I have not experienced any deadstick landings, but do not anticipate it being a problem given the findings I have seen so far.
Of all the VMAR planes I have owned this is the best one of the bunch. It seems sturdier and well designed.
Tommy

RE: VMAR Mig 21
 

A buddy of mine flew his Vmar MIG 21 in a scale fly-in last weekend and all I can say is it was awesome and stole the show. Everyone stopped what they were doing and watched that aircraft fly. He has a Jett .90 installed and the MIG is fast....really fast....and flies like it is on rails. It has almost unlimited vertical and will do multiple aileron rolls at full throttle so fast that you have a hard time counting them. The airplane appears to land like a baby with no bad habits. Having said all of this, it was a fairly windy day, we were flying off grass and upon touchdown, the MIG was captured by the stout cross wind and was pushed into a rough area of the field where it caught a main gear and ripped it out of the mount and subsequently put a hole in the wing sheeting. So, after taking a hard look at the inside of the wing and gear mounts I would offer the following regarding the MIG 21 (only because I intend to purchase one and am going to take my own advice). Try as best you can to beef up the gear mount area prior to mounting the gear. This looked like a very weak set up. I would recommend Springair gear with stout wire struts (the scale struts look fine up close but I think they will be trouble in the long term unless you are one of those dudes that lands perfect every time). Besides, the MIG really looks the best in the air with the prop invisible and the gear up. My friend used mechanical gear and his MIG came out to 10 lbs and some change in weight. I think that is too much airplane for mechanical retracts. Beef up the mounts, install a set of Springairs and you will be set. The Jett .90 engine is a "stump puller" The very high RPMs make it sound very much like a turbine. It really makes the MIG jet-like.....but as we all know the Jett engines are certainly pricey. An OS 91 will handle the job fine i'm sure although it won't have near the RPM. Jett has some engines with rear exhaust and several styles of tuned pipes that go with them. A guy might want to coll Mr. Jett and talk about a setup that would hide/negate the muffler from sticking out the side of the nose and reroute the pipe into the fuse through the firewall. You could exit the exhaust out at a place of you choosing. One last thing......my buds kit showed up with some damage in the box. He had to fix some stuff before he could begin the build. So this is a consideration to those getting ready to shell out some bucks. The aircraft is a very large Jet. I was shocked at the size. But it looks and flies great. What more can we ask for? My 2 cents....Razorback11

RE: VMAR Mig 21
 

Thanks for the flight reports and advice guys. It's a much better feeling going into a model armed with the good opinions of other experienced modellers.

Tom

RE: VMAR Mig 21
 

Can anyone tell me what the max. prop diameter is that will clear the ground? I am going to order one on saturday for conversion to electric.

RE: VMAR Mig 21
 

Just wanted to wake this thread back up. I love my Mig 21 converted to electric. Had some problems getting the plane dialed in but well worth it. The flaps full down make it super stable and easy to land. Problems with the kit: The fuselage is severely warped at the aft section. Both migs at the LHS were like this. The rudder pushrod setup is physically and completely unable to work as designed, and no mention of right engine thrust setting in the instructions, I thought the firewall had right thrust built in, but added 2 1/2 degrees myself after some problematic takeoffs, may also be the warped tail. Now it's ok with the right thrust. In the end, it flies great, and looks great, and a real attention getter at the field. I changed the paint scheme a little, it is very hard to see with the stock all-white scheme if you get too far out, now I can easily distinguish top from bottom. More details can be seen here: http://www.rcgroups.com/forums/showthread.php?t=547663

RE: VMAR Mig 21
 

I was in another post looking to get there(Vmar) F18 , but was convinced not to do so , $329 plus shipping and I was told that it did not look good close up at all , warps , bubbles ect .

RE: VMAR Mig 21
 

Hi Cooler. Can you describe your electric setup? Looks like a great idea!

RE: VMAR Mig 21
 

Look at my Cermark F-16 Tuned pipe sound great. Gets rid of the muffler look!

RE: VMAR Mig 21
 

F-16 Tuned Pipe

RE: VMAR Mig 21
 

HELP.!! HELP. !! VMAR Mig 21.

Two huge parcels just arrived at my door. I didn't hear the courier come and so my wife found them. [&o]:eek::eek:

I am elecrifying this one with a Hyperion 4035/10 outrunner but have NO idea what size Prop is suitable.

looks like 16 x 6 but I want to keep it a small as possible for ground clearance and "Invisibility".

Can anybody help.??? Cheers. Paddy. [8D];):D

RE: VMAR Mig 21
 

A 16x6 is a long prop for that plane, I have one with a st90 and started off with a 13x8 prop and the clearence from prop tip to ground was ok, but i changed it to a 12x7 and got alot better performance out of it....but a 16x6,,, man you are going to be very close to the ground with that one...... I would say you are going to eat up a few prop tips.... You could extend the front landing gear a little bit?????????? maybe?????????

RE: VMAR Mig 21
 

hi all
I got Vmar production ..after crash ..took a look inside ..they are used jungle wood ..not balsa

RE: VMAR Mig 21
 

The nose gear needs to extended a little bit to get a positive angle for takeoff, or else she will just "leap" into the air with heavy elevator. However I don't think you are going to get a 16" prop on there and get prop clearance. Best to try something else there.
Tommy

RE: VMAR Mig 21
 

Oldpilot did you read my ENTIRE build thread on RC groups about electrifying this plane??? A 14" prop is about the maximum diameter you can use. I tried 4 different power setups on this plane... The Hyperion 4035/10 is NOT the right motor for this plane. I burnt mine up with a 14x10 on 8S...and was still low on power. If you want to putt around the sky, 1500 watts will do, if you want it to fly like a jet, you need at least 2000 watts to do it. The best setup would be a 10S setup spinning a 12x10 or 13x10 prop around 10,000 RPM... not the easiest to do with an electric setup, but it is possible. I thought about using the Hyperion 4045/10 on 10S, but totalled the plane before I could test it out. Any questions, let me know...

RE: VMAR Mig 21
 

Hey tank tiger

I"ll bet you have never owned a vmar mig 21!!!! I do have one and the balsa is of high quality not jungle wood,,..... We are talking here about a prop size and electric motor for Oldpilot,, trying to help him out....and the last thing we need is you trying to highjack this thread....go play somewhere else..
If you dont like vmar, then fine,,,,, just go puke it out omewhere else!!![:'(][:'(]

RE: VMAR Mig 21
 

Where can I vmar from in the US?
Thanks.

RE: VMAR Mig 21
 

Hi Doc Yates.

I didn't know about your thread on electrifying the Big Mig. Will read it pronto.

Agreed --at projected 10lbs and 100W/lb, thats 1 KW. [:-].

Don, who is the Australian importer for VMAR thought a 12 x 8 prop might be the go.

Waddya think ???

Cheers, Paddy. [8D];):D

RE: VMAR Mig 21
 

12x8 IF you can spin it fast enough, say, at least 11k RPM or so....I also converted a Cermark F-16 propjet to electric, although I have somewhat given up on that one, just too heavy of an airframe and absolutely terrible landing habits with the extra weight. However, the Mig with the flaps deployed is a *****cat to land, and I think it flew better than the F-16. Not to sound arrogant, but I consider myself the authority :D on electric propjets. You need to not rely so much on the watts/pound rule with electric propjets. Why? Well, when any other glow plane is converted to electric, you know that the electric setup spins a larger prop on the same airplane than the glow engine. Our electric setups also turn that prop slower....so.... glow power=small prop fast, electric=large prop slow. So.....for an aerobatic plane, this is perfect. Lots more thrust than glow. However, what we need here on this Mig is SPEED!! We can't fit a 16x10 prop on it. If we ran a 16x10 @ 1200 watts we would have lots of thrust but only a top speed of about 65 mph. BTW the AUW of the Mig is closer to 11 pounds electrified. So on this plane we need to think of a glow engine, and copy what it does- spin a small prop FAST!! And that is where the watts rule gets a little less reliable. What I have found, with electric, is that RPM= Amps. Lot's of amps, for a good example. look at the large EDF (electric ducted fan) setups. Typically flying a 12 pound plane, they are pulling @ 100 amps from a 10S Lipo setup...we are talking in the neighborhood of 3400 watts!! My first MIG flight was almost a disaster, well the second one was too!! Why? Well, I was pulling "1500 watts" on a 11.5 pound airplane....should have no trouble at least flying, right? Wrong....my 1500 watts was going into a 13x10 prop.....As I rotated after takeoff the Mig began to mush and lose altitude...fast....under full power the Mig landed @ 40 mph cartwheeled and got severely damaged. Why?? Well, my 1500 watts going into a 13" prop was NOT the same as 1500 watts intoa 17" prop.....I was underpowered!! I realized after this, I started using my tach, and found the RPM's at which I was spinning my 13x10 was equivalent to , say. an OS .91 2-stroke spinning the same prop at 3/4 throttle!! Imagine flying this plane glow with the OS 91 and taking off at 3/4 THROTTLE!!!! Disaster!!! Do you see my point now? :D There is more info on my Mig build thread. http://www.rcgroups.com/forums/showt...=547663&page=4 However if you set up the plane right, and USE the flaps for landing you will enjoy this plane!! AND you MUST add right thrust to the engine. there is no mention of this in my instruction book.

RE: VMAR Mig 21
 

By the way, my favorite prop for these jets is the APC 12.5x11.5 "pattern" if you can find one !!

Oldpilot, get yourself a new Flightpower EVO 10S 3700 Lipo, find a motor to handle about 2000-2500 watts and run this APC pattern prop and you'll be happy...:D

RE: VMAR Mig 21
 

Not my thread, but some else's, I have a glow burner in mine. Good luck with it.
Tommy

RE: VMAR Mig 21
 

YES. I really have to do a lot more research on this one. Meanwhile I am concentrating on getting the thing together.
Will be able to post pics after this coming weekend. Have already filled in the huge hole in the side of the nose

I have an Ultra 3300/6 which I have never run. I know it's a brushed motor, but good for 4KW. Heavy---but then I understand from comments on these threads that this plane needs lot of the damned L**D in the nose anyway. Could save me better than $200.00 with the right ESC, and two 5S 4900 Li Polys in series. (Anyone for two 6S Litestorm 5000s in series).

Cheers. Paddy. [8D];):D

RE: VMAR Mig 21
 

Well I had to start somewhere so I ordered an HP-Z-4045-10 motor, backmount and 12 x 10 prop. Am plumping for two 5S 5000 mah Li Polys in series. Should keep the motor and Batts fairly cool as it will be operating at well below the 20C rating of the Li Polys and just under the 12000 rpm safe limit of the motor while giving close to 2KW. Going to "Suck it and See" on the E-meter before going any further. Why 5000 MAH.---I want to get a min of 6 mins at WOT in the air, so that with throttle management it should get 9-10 mins total running time. This is NOT one plane to have to land dead stick, so am going to have to watch that ESC low voltage cuttoff.
After much agonizing about mechanical VS air retracts, I think I am going to go with a set of Springairs as their installation seems so much simpler and I don't have much time for messing around. Our annual May Scale day is on May 20th this year. [:-]

Cheers. Paddy. [8D];):D