Hi
So I had a Cox 0.049 Surestart lying in my drawer. It came with a Cox Back Draft control Line plane which my dad got from the U.S. when I was a kid. The plane never flew (as it was made of plastic and was too heavy), but I salvaged the engine. I always wanted to do something with the engine so last year I decided to build a free flight model for it. I used balsa to make the entire plane and then used lacquer to fuel proof it.
Unfortunaltely, the plane flew only three flights before crashing head first into the ground. (Pic-1)
Too much dihedral (almost 30 degrees) and an aft CG are the main reasons for this crash.
Anyways, this time I decided to go RC so that I would be able to save the plane in case of such faults. I mounted the engine on a test stand (Pic-2)(to check if it is still working after being buried into the ground the last time it ran). Took me a little while, but after 15 minutes of starting the engine and it stopping within 10 seconds, I was finally able to run it for a full tank of fuel.
Now that I am sure that the engine is not damaged, I shall proceed with building a plane for it.
I am planning to build the Lastick, which is a variation of the littlest stick.
Have downloaded the plans and shall start building as soon as I get the balsa. ;D
These are the plans I'll be using.
http://www.youtube.com/watch?v=5XgQhmv5s-Q
http://www.youtube.com/watch?v=cf_ZFkhmXTw
Interesting! Where do you fly in GGN?
I fly in Greater Noida
People do fly in Gurgaon too :D
Hahaha, yes, I am aware of that, but I learnt how to fly from Mr. Kalsi, so I prefer to fly there. Also, I fly very irregularly, only when I'm back home from Manipal.
Got the balsa today. Will be starting with the build ;D
Good plan looking forward to see how it turns out, 5 Deg down and 3 Deg right seems too much, you could review that. this plan is for 0.010 will your 0.049 go with it ? just a passing thought
Thank you sir, will take the thrust angle into consideration. As for the engine, I don't think it should be a problem, as the previous plane I built was also of a similar size and that flew well (except for the cg issue). It had sufficient power, though not enough to go vertical, but it was a free flight and was heavier due to a full balsa wing. This will be lighter as I am using covering and hence should be a bit faster. If the engine doesn't work, I'll make a bigger one next time.
Ummm, how much should I keep the thrust angle? The engine spins the 5x3 prop that I'm using upto about 16,000 RPMs. (Not measured by me, taken from the manufacturer's website)
5 Degrees down thrust should be ok if you keep the CG a tad back say 25-30%. it will be a slow flyer.
else 2 degrees down and 2 degrees right with CG at 15 to 20% should be ok.
In this case since you are using a 0.02 plan for a 0.049 engine it will as such nose heavy and 2 degrees should be fine
I want it to be fast....so 2 degrees down and right should be ok?
Absolutely
Thank you sir!!
Hi, would the stab and elevator be enough, they seem a bit small to me.
Laying out and cutting the plans.
Cutting the Ribs and Spars
Test fitting the components of the wing.
looks great maahin {:)}.
you have to bring this to manipal (:|~ ;D
Subbu
Will try..............provided I haven't crashed it till then :P
Gluing the ribs to the first spar
First spar glued.
Gluing the trailing edge.
Gluing the leading edge.
Gluing the final spar.
Gluing balsa sheet to the center of the wing
The completed Wing
Gluing the Fuselage sides
Drilling holes for the Dowel rods
Nice!!!!!! :)
The completed Fuselage.
Looking good. Laser cut?
You mentioned 16000 RPM taken from the manufacturer's website. Cox fuel has a very high percentage of Nitromethane. Which fuel will you be using?
No sir, the parts are not laser cut. I just used a simple paper cutter ;)
I shall initially be using just methanol with 20% oil, then if need be I will increase the nitro content. Though, yes, the manufacturer's website quotes performance figures for 25% nitro
Verynice workmanship.
Pl consider tissue and dope for wings. Old fashioned but saves weight.
Best of luck.
Already bought Monokote. Shall be starting with covering tomorrow.
1. Monokote. Wing loading 12.5 oz/sqft
2. Oracover. Wing loading 10 oz/sqft
3. 6oz/sqft
For a Cox .049 without nitro, you should be in 6-8 oz/sqft range
Look at the quality of the joints.
Hard to believe it's a beginner with a paper cutter.
Either laser or an experienced old style builder.
How many newcomers have a Cox now?
Sir, reveal yourself!
Thank you, and will keep that in mind for my next build. Just hoping that my oversized engine would be able to take the weight. :/
Hahaha, no really, I have only assembled two 46 size ARFs and done one scratch build before. The scratch built plane was for the same engine and it crashed on its third flight only. The CG was too aft and as it was free flight, I was able to do nothing to save it. Watched it stall and dive head first into the ground at full throttle. :(
As for the Cox, I was always interested in planes so my dad got me a controls line plane from the US when I was around 8 years old. The plane got damaged in transit while we were shifting our house and thus never flew even once. I wasn't able to do anything with the Cox as I didn't have the fuel and didn't know where to get it from. It's only recently when I got introduced to aeromodelling that the fuel and equipment became available to me. The engine had been run before and had been lying in a drawer for 9 years. I just sanded the electrical contacts and filled the tank with fuel and attempted to turn it over, not at all hoping that bit would start but it spluttered and half an hour later, I was able to run it for a full tank. Then I decided to build a plane for it.
Pl feel free to pm me for any help with the Cox
Thank you, the help is much appreciated :)
My homemade covering iron ;)
I shall be using the following control horns:
http://hobbyking.com/hobbyking/store/__8419__Control_Horns_16x20mm_10pcs_.html
I don't have the screws for these.
Can I stick them with epoxy, or do I need screws?
covering iron or covered iron? :P
i use the same method, albeit with a smaller iron
Covering the Horizontal stabilizer. Covering is a little loose. Am I tacking the covering at too high a temperature? Or do I need a higher temperature to shrink it?
Covering the Bottom of the wing. Covering is still puckered. Any tips?
Fantastic Build!!
Any tips regarding the covering, in reference to my previous post?
The covering will first be tacked down at a few places around the frame, then it will be sealed at all the edges, then shrunk tight.
I Think it's time to shrink the covering. With the iron set to 300°F, apply heat using the same pattern used to apply the covering starting at the spar and working outward. It may be necessary to increase the temperature to 320°F to get rid of stubborn wrinkles. Use the minimum amount of heat necessary to tighten the covering.
Tanmay..
Covering the Top of the Wing.
Covering the Fuselage...
Completed Fuselage ;D
i m new and i want to buy a rc plane which has to be pnp and no further acceseries is
required .so plz suggest me an aerobic plane from range 5000 to 9000 or may be
10000 so plz suggest me............. :headscratch:
10,000 with transmitter included?? Or do you have your own radio system?
All parts, covered, ready for assembly..... ;D
Clean Build.. :thumbsup: :thumbsup:
Making a pattern on the wing
Hinging the Control surfaces:
Rudder-
Elevator-
Ailerons-
I need some help regarding the servo installation.
I am going to be using HXT900 servos all around and need to know how they handle vibration.
I have read many reviews, however I haven't come across any where they have been used in a glow powered plane.
As the servos don't come with rubber grommets, I shall be mounting them by placing a piece of a cycle tyre tube to act as a grommet ;)
Also, can I attach the control horns by gluing them (fevikwik or epoxy) or do I need to screw them in.
I ask this because I don't have proper screws with my control horns and then ones I have, have very big heads. They will work, but won't look very nice.
Come over and collect some grommets from me
Sir, grommets are not a problem, I just wish to know how the hxt900 operate under vibrations. I also wanted to know if its safe for me to glue the control horns
Installing the servos...
Rudder & elevator push rods should ideally cross in the fuse
This is not essential (crossing). But make sure there is no fouling under any situation. Maybe it's the angle of the photo, but your servo arms look dangerously close
They are very close, but I test fitted the rods and they are not touching each other or interfering in any way.
Do not glue in the Horns. A failure there will be catastrophic
Yes, I shall screw them in. I have finally managed to find screws that fit ;D
Installing the engine...
Installing the fuel tank...
My AAA NiMh battery pack, successfully soldered and covered with heat shrink
Rudder control horn and control rod installed.
Elevator control rod and horn.
Aileron servos, control rods and control horns.
Plywood skids glued at the bottom to protect the bottom of the fuselage from stones while landing.
Putting all the components in the fuselage (Very tight fit)
Ready to fly ;D
Went to fly the plane today.......
Spent two hours trying to get the engine to start, without success.
*sigh* Back to the test stand :(
Engine doesn't seem to be sucking enough fuel. It starts up alright but then stops within half a minute. After it stops, it has no fuel in the chamber and I need to prime it again. I have checked the fuel line and there are no bubbles. Planning on dismantling the engine and checking inside for dirt or other things that may be blocking the path of fuel.
Saw a video online for the .49 sure start engine. What they do is they keep the fuel tank above the level of engine so that fuel can flow into the engine. That could be a reason, please consider.
As per my understanding in most of the engines there is a air line that goes from exhaust to the fuel tank which provides pressure and the fuel rises into the intake of engine. However we dont this kind of architecture in this case. So would suggest try mounting the fuel tank above the level of engine.
Regards
How many number of turns you are opening after fully closing the Needle? I hope it is three.
You do seem to have a air vent. I hope it is above the fuel level in air inside tank?
If it all above it correct then I think you should check the reed valve and the Needle washer.
If it is a old engine running after a long time. I think you should open and clean all the above once in fuel.
Nice build by the way. Its a beauty. :thumbsup: Film could have been shrunk more to give it a smooth finish.
@punty. Cox do not need air pressure line. And fuel tank has to be kept level with the cam. Even if kept low it can suck fuel being a reed valve engine.
@Sundaram.. Thanks for correcting me sir:)
Actually I wasnt sure about this thats I said saw it in a video. :) Do have a cox engine but didnt get a chance to learn it.
@Sundaram
Sir the air vent is as high as it can possibly get, if you look at the attached picture, the air vent pipe rests in the notch at the top of the tank.
I am running the engine at 4 turns of the needle. The manual suggests 3 turns however, this engine does not start at three. I have run it a few times before and it started at 4-1/2 turns, reaching full power at 4 turns. I even test ran the engine on the test stand before I started building the plane and it ran for the complete tank without any problems.
All that aside, it is an old engine and not very well maintained. It is about 8-10 years old. I got it with a Cox control line plane that my dad bought when I was a child and it was started a few times then, but then the plane broke in transit and it lay in a drawer until very recently (about 2 years ago). Even then, I just put in fuel and started the engine as I was scared of opening it, so basically it has never been cleaned from inside.
Hence I plan on opening it and cleaning it with fuel. The cox manual suggests leaving it overnight in isopropyl rubbing alcohol and then dipping it in fuel for 5 minutes to re-lubricate the parts. Is this suggestible? Also, can I leave all parts of the engine in rubbing alcohol?
1. You are using straight fuel (without nitromethane) it will make a difference in your needle setting. Nonetheless, try cleaning your needle valve assembly thoroughly: there may be some kachra
2. Be careful not to put rubber and plastic parts in alcohol
Ok, thank you sir
Anytime :D
maahin : try to clean with WD40. am using same for cleaning the carb of my nitro buggy :)
Amazing and detailed build log. Thanks a lot for putting such a detailed build log. Hard to believe that its hand cut :hatsoff:
Finally managed to get the engine running. Had to chuck the thinner Cox fuel line for regular silicone fuel line. Now it's running perfect.
I shall maiden the plane tomorrow. Will post the video.
Very very nervous.
Don't be :D
best of luck for tomorrow. will be your first flight since the holiday right
Subbu
Nah, I flew my Seagull 40 this Sunday ;D
good for you, its raining all the time in here
Subbu
Sad :(
Good time to build!
Ok, so I am still facing problems with my engine. The engine runs fine as long as the starter battery is connected but stops the moment it is disconnected. If I disconnect the battery and connect it again very quickly, the engine splutters and then starts again.
Will be checking with a new glow plug, but are there any other suggestions?
Plug.
Planning on converting the stick to electric.
How would the following setup be?
The AUW of the plane currently is around 350g and removing the engine and fuel tank will save around 120g.
http://hobbyking.com/hobbyking/store/__19034__Turnigy_Park300_Brushless_Outrunner_1600kv.html
http://hobbyking.com/hobbyking/store/__11899__Turnigy_nano_tech_850mah_3S_25_40C_Lipo_Pack.html
http://hobbyking.com/hobbyking/store/__2163__TURNIGY_Plush_25amp_Speed_Controller.html
6x3 APC Prop
My main concerns:
>I would like around 10 minutes of flight time.
>As the plane was not initially designed for electric, it has no ventilation, hence the 25A ESC even though the motor will only draw 7A (I would prefer not having to cut holes now, as the build is complete)
I have referred to the follwing site for calculations, and it shows that I should have a little over a 1:1 thrust to weight ratio.
http://www.ecalc.ch/motorcalc.htm
Your model is heavy - as per plans it should be 5 1/2 0z or 156 gms. I don't see any significant weight gain in switching to electric, if that is the reason for the shift.
I would suggest a slightly more powerful motor, about 110 W so you could swing a 8*4 or 7*4 (nearest available) SF prop at about 1500 KV. This will give the thrust needed, which will be required at lower throttle. Select the ESC & Battery to suit.
If I recall correctly, the main problem was the engine cutting out. Maybe try 10% Nitromethane?
BTW, HK shipping is taking about 5 weeks nowadays, and they have again stopped shipping LiPos by Airmail :( :(
Sir, could you suggest a motor?
I'm coming back on the 20th of December, so if I order in the next few days, hopefully it should arrive by then.
Also, I am ordering an Accucel 6 charger as well, so I might be able to get the total weight of my package around 1 kg and then use FedEx
How about this:
http://hobbyking.com/hobbyking/store/__27289__Turnigy_2205_34_1500kv_Brushless_Motor.html
Seems like this motor should be fine.
Maahin, do also give a thought about your next two models after the La Stick. You buy a motor, it is not just for one model. You do want some versatility too.
eg I have a 2826-1400 & a 2836-1400. With these I have a whole range of builds open to me, including the entire FT range, the Avispad family, and several ARFs, balsa kits and foam ARFs. Do give this some thought :D
Would the 2826 be too big for this plane?
Also would the 2826-2200kv be able to turn a 7x4 prop??
Nothing can replace the pleasures of flying a 1/2A Glow.
I would recommend don't loose the battle with Cox. if it has a good compression it is one of the most reliable engines to start. Least faults. Starts every time before the fourth flick. I use a spring starter.
Ok if your engine has good compression then there are only three problems for starting problem.
Glow Plug, Reed valve and 'O' Ring of the needle. If your engine is starting well and running with booster then last two problems are eliminated. The Problem is only glow plug.
Now open the glow plug see that the filament is intact and clean from outer tip till inside the base. Since engine unused for long, chances of debris are high. Thinned out filament due to long use also can cause such problem. This you check under a good light condition outdoor with preferably a lens. Clean if any debris are present with soft (one - two) bristle. Compare with a new glow plug of any type if you are new to glow. if possible Replace with a new glow plug if you can source it.
Hobby King has the replacement glow plug
Sir, I did clean out the engine with methanol from inside. The glow plug is not blackened from anywhere and glows bright. I have an OS Glow plug adapter for the cox as well. I used that with a No. 6 Glow plug from my OS engine. With this glow plug, the cox did not quit, but it didn't seem as if it was running at full power.
I am definitely not giving up on the engine, just keeping it aside for now. Besides, there are other reasons why I want to shift to electric.
>Firstly since the plane has come out very heavy, I'm not sure whether the cox can take it or not. Even if it can, it would not glide very well and thus landings would be very hard since all landings will have to be deadstick.
>Secondly, and this is one of the main reasons, I would like to take this plane to college with me, and hence electric would be much easier.
If you are using Adapter you are likely to have a variation in compression either too high or low. You are required to adjust by increasing or decreasing number of Copper Shims. to get Optimum Compression and performance.
Good Luck. :) :thumbsup:
Sir, I have 3 gaskets, I tried with all possible combinations. I got the best results with 2 gaskets, but wasn't impressed.
I am using fuel with 20% castor oil and no nitromethanee. Although many people say that Cox engines run just as well without nitromethane, I think I will have to add atleast 10%. I remember with the freeflight that I made. Even then the engine wasn't starting, but at the time I was using the original glow head and did not have even a single head gasket (dropped it somewhere in the field :banghead:) hence I was losing a bit of compression.
Adding a drop of nitro to about 100ml of fuel and then using that fuel solved the problem.
Cox recommends Nitro content of more than 15% say close to 20% for good power. Even though cox starts and runs as well without Nitro definitely there will be a drop in performance.
:) What is the Max RPM and on what prop size? Only RPM can give you idea and an estimate of power achieved.
Cox is too small an engine to estimate power by feel of thrust or visual or gauging by hearing, although with experience you can.
If you are able to achieve an RPM of more than 12000 with 6x4 or 13500 with a 5x3 two blade or three blade then its is good since in air it will pickup RPM. with good nitro you can reach RPM close to 16000 and with better design improved engines you can reach 18000 RPM.
Cox Surestart can easily give a thrust of 200-250 gms of which is very good for a model of AUW 350gms.
Guys have flown a good gliding models close to 1 KG with cox.
I'm using a 5x3 cox prop. Though I have no way to measure RPM
Sent from my GT-S7500 using Tapatalk
If your engine does not peak High RPM more than 13500 then 5x3 is a problem for thrust.
Ready for maiden once again.........
This time with 2826-1400kv motor turning a 7x4 prop and a 950mah nano tech battery.
Setup draws 14 amps at full throttle. Thrust does not seem to be a problem.
I haven't measured the AUW as I don't have a scale but I'm assuming it should be around 350g.
That looks awfully nose heavy , and overweight too.
- at least check your cg before you commit
On the contrary, it should be a little lighter than it was with the cox.
Also, with the cox, it balanced perfectly on the main spar, now it balances slightly behind the main spar.
I really like the color of the plane thats good !!! :) ;)
Wanted to go for the original stick look with the black cross on white, but didnt have white or black monokote. Only had a scrap of orange left.
Maahin use vinyl, i will get some for you to the field on sat
Maiden (and last) flight video:
http://www.youtube.com/watch?feature=player_embedded&v=cEOax9YGtns
Hota hai..hota hai...
But I love your spirit...see you soon flying some plastic...
Great video mahin sir :) ;)