Should I give up on the FMA Razor??? - RC Groups
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Jul 06, 2002, 12:30 PM
soholingo's Avatar

Should I give up on the FMA Razor???

I bought this plane about 3 months ago and after getting it to fly, I crashed it. However after the repair the plane refuses to fly level and straight. Here is what happens...

I launch the plane and within 10 feet it does a roll to the left, and straight into the ground. I correct this tendency by adjusting the the trim accordingly and it looks as if it's going to fly, and then it rolls left, and over again crashing. I must have had 20 launches with the plane crashing before I gave in.

Any suggestions? Thanks.
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Jul 06, 2002, 12:43 PM
Registered User
Patrick Plawner's Avatar

no, you should not give up

Rule #1: Don't let a plane make you give up !!!
(Unless he is really gone...)

In your case, I think, before really letting it rest in peace, you should maybe check, if not already done:

- If the motor is still strong enough. Some crash could have damaged his power
- If the Servos still behave ok
- If there is no bend, anywhere, and the weight is balanced Left/Right
- That there is no interference between Motor and receiver. Test it on the ground
- That the receiver is not working crazy, could also happen after some crashes.

- if the CG !!!! is not messed up. As what you described, could really be related to a messed up CG
- Is the receiver antenna, still well connected to the receiver ? As some crashes could have sectionned it, and then, after few meters from you, the plane would go nuts, like what you are experiencing.

When you'll find what is happening (and I am sure you will), please share it, it is interesting.
Last edited by Patrick Plawner; Jul 06, 2002 at 12:50 PM.
Jul 06, 2002, 12:52 PM
Registered User

You sure plane is flying?

I only have a few flights on a razor, but many on Zagis.

First make sure CG is correct

Then make sure up is up and left bank is left bank, and right bank is right bank, you may have controls reversed

make sure max up and down throws, are not too great, my dart throw would be to limit to 1/4 inch up and 1/4 down, and go from there

if you have a dork speed 400 prop, make sure you have it on correct, lettering face backwards

do a range check with radio with motor on full

make sure you do not have any warps in wing, if you do, slit wing and untwist and fill slit with probond

__________________________________________________ __________

My gut is you are not getting the airplane to fly. Not enough airspeed.

Always launch into the wind, even if it is blowing 3 mph

You need to heave ho the plane, do not aim too high, just 3 feet off ground with good followthrough

Try gliding it off a slight hill into soft tall grass till you get it sorted out, have no intention of adding power till you can glide the thing and land it. Keep up airspeed, if it seems like it does not have enough control, it is probably because you are not flying fast enough and at or near stall.

If you have a heavy plane, are flying at high altitude, in hot and humidity, you will have a real high stall speed, requiring a real good toss

you may want to bungi launch if the above is true. 20 feet of surgical tube, 50 feet of fishing line, doggie tie down, and electrical extension cord reel to store it. tie white rag to end, mount tow hook 1 or 2 or more inches foward of CG. The further foward the more stable, but less altitude, the more aft the more you need to work but can get high launches. since you are only interested in getting airbourne, start 2 or 2.5 inches ahead of CG.

best advice of all, is get an experianced pilot to sort out and get it flying, then hand over to you.
good Luck
Ron Parigoris
Jul 06, 2002, 12:58 PM
Registered User
hi Soho ....... are you an experienced E- RC flyer, or is this a new thing (rc flying) for you ?? it might make a difference ....... kw
Jul 06, 2002, 01:50 PM
Registered User
saint152's Avatar
From the characteristics that you described.......sounds like you're tail heavy...... Double check your CG and even move it forward 1/4 of an inch.....Once you get it flying..... you can start moving the CG back until you're comfortable with it's performnace.

Don't give up!.... FMA Razors fly really well!
Jul 06, 2002, 10:24 PM
Embedded Systems Engineer
MX's Avatar
I agree with rparigoris. My Razor did similar things until I realized
I wasn't throwing it hard enough. It seems to need a lot of speed
to get going right. Throw it like you are throwing the long bomb
in football, but straight and only slightly up.

Jul 06, 2002, 10:49 PM
Registered User

This was my Razor problems.

I had a Razor that wouldn't fly right AT ALL!. I tried Everything!
Then I found the my pack was moving when I threw it so the CG was wrong all the time. Check the CG and make sure the pack and equipment is really secure. Also check for lateral balance place a finger on the spinner and center of the nose if it tips one way add a bit of weight, Screw or what have you.

In flight keep the speed up in the turns at all times as it will tipstall if you let the speed bleed off in the turns.balance abit nose heavy, about 1/8 to 3/16 forward. A nosee heavy plane will track better but a tail heavy plane can be unflyable. Put a bit of reflex ( up on the elevons ) to give low speed lift.

Try that first. I have A lot of experiance with the poor old razor but now it's my most flown plane by far!
Jul 06, 2002, 10:56 PM
soholingo's Avatar

By Cracky that's it!!!!


it's the changing CG!!!!!! The pack is mounted in the slot though not securely, it doesn't appear to be moving, but even after the radical corrections, the plane will do a wild flip.

I think that's it... i will secure the packs try it again...

Jul 06, 2002, 11:40 PM
Rehab is for quitters
LuckyArmpit's Avatar
For my Razor, I put velcro in the slot and velcro on my batt packs.
They never move. Also, the Razor likes to be just a tad nose heavy. At least mine does and it flies great that way. I don't even give mine a hard toss to launch. I launch on full power with a straight toss and off it goes. Once you get it going and get the hang of it, set all your controls at 100%. Its a blast to roll and loop! Its one of my most stable flyers.

Jul 07, 2002, 02:05 AM
Registered User
If a shifting CG is not the problem, what kind of repair did you have to do to it after the first crash?

I had a plane (a conventional layout, not a flying wing) that crashed on the first flight and broke the left wing off. I quickly glued the wing back on, then tried to fly it later that day. Every single launch resulted in a roll to the left and diving into the ground. A later examination of the plane showed that I had glued the left wing back on at a slightly lower angle than the right wing.
Jul 07, 2002, 12:49 PM
Registered User

Glad you found it.

A little velrco on the packs and on the bottom of the battery compartment did wonders for my plane, and a good Idea on any razor to keep the pack from moving.

After a few crashes on mine I would hear strange sound as I threw it. The harder the toss the louder the sound and the worst the plane few. When it crash ( of course) the pack went forward again, so it was hard to figure out.

I lanch mine without power and it will glide for about 60ft., level. Just enough time for me to level the wings and give it the juice, and away we go. mine runs on a long Johnson 600 that will turn an 8X5 prop @ 13,100 RPM , it really moves with 8x800AR packs.

Hope it helped and enjoy the razor, it really is a great flying plane, it will do almost anything and it is really tough, as you have found out.
Last edited by D.FLinn; Jul 07, 2002 at 12:52 PM.
Jul 08, 2002, 12:43 PM
Over Engineered
Robert Hoffman's Avatar
I agree with low air speed or shifting battery. If you let a Razor get to slow and try to turn too steep they do a death spiral. Fix the battery with velcro, check CG (make sure it is a little nose heavy), check right to left balance and give it a good throw. My first set of wings were beat up bad and it still flew. Once in the air keep the turns gentle until you get a feel for it. When the pack is low do the same. Last night I forgot this when I was gliding in for a landing with a low battery and tried to get just one more turn at about 15 feet up and it fell out of the sky like a brick. Flying wings tip stall very easy. The good thing is I put a new battery pack in, did the regular checks, no damage and flew it 4 more times. Do not give up. You'll love it once you get the hang of it.
Jul 08, 2002, 05:25 PM
Registered User
Batteries on the FMA Razor should be ALL THE WAY FORWARD. I'd almost suggest adding a little weight to the nose or cut some foam away so the battery can sit further forward. Same thing with a Zagi. Anything further back than full forward and it will tip stall and do this nastly little snap roll thing at the top of loops. A Zagi or Razor should flutter slightly but remain in control with power off and slowed to full back stick. If it doesnt, move the battery forward. Good luck! The Razor really is a nice flying wing.
Jul 08, 2002, 05:35 PM
Professional Dork
Randy S's Avatar
The location of the battery pack depends on what kind of batteries they are. I use lots of different packs, and they all balance at different locations. Generally, the bigger and heavier the pack, the further back I have to move it. As for tip stalls, they have never been a problem.
Jul 08, 2002, 07:16 PM
Rehab is for quitters
LuckyArmpit's Avatar
I also run different size and style packs in my Razor. It depends on the pack on where they are located in the pod. For 600 AE hotdog style packs, they are the furthest up front. For brick style,
I have to put them about 1 inch back from the front or it will be too nose heavy. Like I said before, the Razor likes being a little nose heavy. But too nose heavy and it really drops on low power.