Re: small Q&D 049 racer

Amper Fri Nov 25, 2011 8:07 am

*Mayday Mayday ! Aileron failure, q&d is going down, repeat, q&d is going down !*

Today i had a total failure of the aileron due to the servo, that decided to fall apart mid flight. I Hat the Engine running on full power and only the elevator as control. But a few very frightening loops after I managed to get down safe and without a scratch,

I would be careful with hott, there are others, that are far better. and not that native to Graupner. Again i have to point at jet, the duplex modules can be put into ANY transmitter no matter, what manufacturer, you not even have to change your equipment except for the recivers.

Georg(e)

EDIT: New modification on the plane:

The motor is mounted on vibration reducing rubber mounts, now the CG is in a better place and the fuel coming from the carb doesnt go directly into the wooden Plane.

small Q&D 049 racer - Page 2 Dsc08473h

Hopefully next week I will get to the lathe and make a muffler, but more for directing the oil spit than getting it more quiet. The mess of 4ml castor oil on the wings and fuselage after every flight is really nasty...

PV Pilot Fri Nov 25, 2011 10:05 am

Amper wrote:*Hopefully next week I will get to the lathe and make a muffler, but more for directing the oil spit than getting it more quiet. The mess of 4ml castor oil on the wings and fuselage after every flight is really nasty...

Yep, messy stuff. here is a concotion that works excellent for wiping down the surfaces after flying or flight. I usually mix up a gallon and use a solvent/cleaner sprayer or ?? from Home deopt or where ever you can find one.

•5 cups water
•1/2 cup of ammonia
•1 cup rubbing alcohol
•1 oz. of DAWN dish detergent
(I use the Dawn Ultra concentrate, but at the same ratio.)
Mix all ingredients in a clean milk jug, pour enough in a small spray bottle for field use. This solution cuts thru the oil buildup on the underside of your plane and leaves it squeaky clean.

CAUTION: Dawn seems to be the only dish detergent that cuts all the oils and doesn't leave a residue on the plane.

I emailed Mecoa as to when they might remake the Tatone 1/2A muffler clamp style with the stinger off to one side and back. They said next year on that piece.

andrew Fri Nov 25, 2011 11:20 am

Amper wrote:

Today i had a total failure of the aileron due to the servo, that decided to fall apart mid flight. I Hat the Engine running on full power and only the elevator as control. But a few very frightening loops after I managed to get down safe and without a scratch

............snip..............

The motor is mounted on vibration reducing rubber mounts, now the CG is in a better place and the fuel coming from the carb doesnt go directly into the wooden Plane.

I think many times the smaller IC planes are "under-servo'ed" (how's that for a made up term?). In the effort to install the lightest, smallest servos, the ultra-micro servos used in park flyers get the call. I don't believe these planes need the larger servos for the torque; they need a more substantial servo for the geartrains. When the servos are downsized, the geartrains must be made smaller and, as a result, are less robust. Under the vibration of .049/.061 engines running 15 to 18k, they can spit teeth like a drunk in a bar fight. They are not subjected to these vibrations when flown on electric planes.

Have any of you ever noticed when tuning from a rich 4-cycle to a flight ready 2-cycle that the airframe may buzz. It's caused when vibration from the engine is some perfect multiple (or close) of the natural harmonic frequency of the airframe and vibration in the airframe is enhanced. The effect on the servo is similar to flutter, i.e., the geartrain gets a lot of high frequency load reversals and the tiny teeth cannot stand up under the strain.

I may err in the other direction in that I mount a servo that is over-speced in the plane, but I'm willing to give up 6 grams and an additional $8 on a couple of servos to have metal gears in place of the lightweight nylon gears of the 5 to 9g servos. For me, it may represent the entire cost of a plane if I end up bringing it home in a sack due to servo failure and some "peace of mind" that I've done all I can do avoid mechanical failure.

Sounds like you're moving the right direction in reducing vibration. Good job in recovering from a servo failure.

PV Pilot Fri Nov 25, 2011 1:19 pm

Very important to NOT crank down the servo mounting screws in the rubber grommets. I just run them down till they touch the rubber, then about another 1/2 turn. I have gone to making the servo tray or platform mounted on soft rubber bushings that I get at Ace Hardware as well, to try to isolate as much as that uneeded vibration as possible. Some of it is going to get thru, but it can be lessened to a couple extra degree's just by thinking things thru before flight.

Amper Fri Nov 25, 2011 1:39 pm

You are totally right, but the reason in this case wasnt the gear that failed, it was the housing. It might got lose when i refueled the Plane, then in the air the casing got off and the motor fell out since those small Servos are not screwed together.

small Q&D 049 racer - Page 2 Dsc08475v

But im not sure this was the reason or the servo cable, that was ripped at the plug.

Anyways, no matter, what of the two was cause and what was result, Servos are something, that has to be cared about, not so much luck and the Plane would have been a pile of toothpicks.

Georg(e)

Jaspur_x Fri Nov 25, 2011 6:27 pm

Cool that it was a good flight and flies well, I thought the nose looked a little short, but that can be deceptive.
Now I want 1 lol

Try getting video for us next time? Might inspire us all to build 1
We would really love to see how she flies

microflitedude Fri Nov 25, 2011 7:57 pm

You may want to look into using two servos for ailerons - that way, if one fails, you still have some control. I have flown electric airplanes with one servo unplugged without knowing it. Very Happy

Amper Sat Nov 26, 2011 2:13 am

I originally planned to do so, but the Wings are very slim and i would have used 1.6g servos to fit the Wings and those are by far not reliable enough.

I might try to make a video today, but first I need someone to hold the Camera ^.^

nitroairplane Sat Nov 26, 2011 4:38 am

Amper wrote:I originally planned to do so, but the Wings are very slim and i would have used 1.6g servos to fit the Wings and those are by far not reliable enough.

I might try to make a video today, but first I need someone to hold the Camera ^.^

I will

shell shock Sun Nov 27, 2011 6:36 pm

Amper wrote:maiden

The front is a bit to light, but except for that it goes pretty good, it needs some adjustment of the motor angle and the wings will go 1 or 2 cm to the back to get the cg right.

The speed is nothing for beginners, but still good to handle. Even with the additional stone weight in the front it went up vertical with out effort.

Maybe i will try it again later today, but its freezing cold outside, i didnt even feel, when the prop cut off some skin off my finger ...

cheers Georg(e)

jeez man! where are you? Arctic?

Amper Sat Dec 10, 2011 10:38 am

Hi, today i put in a new servo and did some repairs, also i made a new start spring like the older models Very Happy

The original sure start spring has to much drag on the plastic clutch so i decided to make one the old style, after 2 test springs the final one works pretty well and retracts nicely, no contact to moving parts in operation.

and thats what it looks like :

small Q&D 049 racer - Page 2 Dsc08585z

High resolution: https://2img.net/r/ihimg/f/205/dsc08585.jpg/

Also i took the fuel pump of my jet engine, strapped it to the fuel canister and added some hosing. It seems to work really good so maybe i will make a better more solid version with the starter battery included so i have like a ground station for refueling and starting the Plane.

small Q&D 049 racer - Page 2 Dsc08592z

High resolution: https://2img.net/r/ihimg/f/155/dsc08592f.jpg/

cheers Georg(e)

nitroairplane Sat Dec 10, 2011 10:39 am

Nice!
I like that fuel pump.

Amper Sun Dec 11, 2011 6:15 am

Yea, its a nice pump, but not quite economic if you dont have it already, for the price of it i could have gotten 4-5 brand new .049 engines Surprised

Ive just been outside, everything shockfrosted, but later on the sun came out and its just beautiful weather to fly, with the pump no bottle or syringe action is needed, just land, put the needle in, press the button and restart the motor Very Happy

cheers Georg(e)

btw the spring starer works just wonderful Very Happy

PV Pilot Sun Dec 11, 2011 8:25 am

Amper wrote:Yea, its a nice pump, but not quite economic if you dont have it already, for the price of it i could have gotten 4-5 brand new .049 engines

Ive just been outside, everything shockfrosted, but later on the sun came out and its just beautiful weather to fly, with the pump no bottle or syringe action is needed, just land, put the needle in, press the button and restart the motor

cheers Georg(e)

btw the spring starer works just wonderful

Those are a expensive, very precise, variable load/speed pump. Basically the throttle venturi for a model turbine. On the bigger turbines they run up into the thousands for that little pump because they are so stable running.

Amper Sun Dec 11, 2011 9:17 am

Yep, these gear pumps are expensive, but high performance and quality has its price. This particular one can supply 700ml/min at 6 bar pressure with a peak of 10 bar. The only reason for using it as refueling pump is, that the Turbine is making Problems at the moment (defective ball bearings).

The plane is absolutely awesome, i just blew 400ml fuel into the atmosphere, that was one awesome afternoon, now the sun is gone and the batteries are charging for tomorrow Very Happy

PV Pilot Sun Dec 11, 2011 9:20 am

Amper wrote:Yep, these gear pumps are expensive, but high performance and quality has its price. This particular one can supply 700ml/min at 6 bar pressure with a peak of 10 bar. The only reason for using it as refueling pump is, that the Turbine is making Problems at the moment (defective ball bearings).

The plane is absolutely awesome, i just blew 400ml fuel into the atmosphere, that was one awesome afternoon, now the sun is gone and the batteries are charging for tomorrow

Very cool. which turbine do you have?

Amper Sun Dec 11, 2011 9:29 am

A home made 180N class one, it was just finished, when for some Reason i not know one bearing got stuck completely, luckily at "only" 35000rpm (idle), but the compressor wheel is broken and both hybrid bearings are dead. I guess, it was caused by debre, but ill never know for sure...
If you are interested look here (german): http://forum.mosfetkiller.de/viewtopic.php?f=3&t=8448

Sponsored content