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Mini Arrow - 2nd plane...

#21
Just one other thing that I forgot tomention on my earlier posts is that having elevons that are easily twisted or somewhat soft and flexible can give poor deflections at maximum speed leading to very poor roll and loop responses as the elevons will tend to flatten out due to the twisting of the control surface. I give mine a good coating in Miniwax or equivalent to stiffen them up.

have fun!
Ill have a look at that thanks, although im not doing rolls at speed. The west foamboard im using seems pretty strong, the paper i think is thicker than what other foamboards use.

I reset everything up. found the original eleveon setup gauge and found that there was a difference between the new one and old i had made, the old one had slightly more angle to it. So used that and found i needed a fair amount of subtrim to get the reflect from the original guage. So its possible the 2nd gauge i made didnt get cut properly.

I also rechecked the balance inside out of the wind. Adding 15g of weight to the nose which brought it to within 1mm of the 1.75 inch mark.

I also made new stabilisers rather than glue the old one back on, so i could use the alignment marks.

I have wingtape coming and also filament tape, Ill make another wing but this time with the paper removed on 1 side to compare the weight difference. And ill also do one with paper removed on both sides and covered with wing tape on the outside. I think this is going to be enough to make this foamboard to work as it should get it to around what ft stuff weighs
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#22
Sounds like a plan.

I would recommend using a strip of fibre tape alone the LE in case of rough landings!

have fun!
 
#23
Sounds like a plan.

I would recommend using a strip of fibre tape alone the LE in case of rough landings!

have fun!
Well, i dont believe it!. Hand launched without a fuss carried on at a nice angle UP! giving me plenty time to get the controls. First flight needs a fair amount of up trim to stop it diving to the ground, but it was way less than before and it flew fine. nice and predictable had to give some aileron trim aswell to stop it slowly banking right.

Now the confusing thing, the 2nd battery, same aggain it hand launched with ease, but it wanted to clime so i halfed the amount of trim i used, and it was also rolling right again, this time i was almost full left aierlon trim. But flightt characteristics were the same nice and smooth and very calm.

Roll rate is still a tad slow. Doesnt roll straight but thats probably an elevator trim issue, and/or play in the linkages.

Need to look at the hinges, 1 elevator mores alot easier than the other, its probably missing the hotglue reinforcment.

Both flights landing was nice and soft, after getting slow enough just killed the power and help back on the stick to keep it level and it gently sat down. Now that im not fighting with it i can fine tune and move to catch landings. Iw ouldnt say it flies super slow but its slow enough to be able to catch.

Awesome.

Ill still build a 2nd one, ive got sheets to use up. I want to also build the FT3D and if removing the paper does the trick ill do that with the FT3D aswell;

Thanks for the help!
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#24
Sounds like you almost have it beat! Congratulations are in order!

The change in roll and pitch trim can have a number of tiny causes. Upon landing you need to make sure that the landing did not change the alignment of the winglets. The CG might have changed slightly if the new battery was a different weight or not installed in the exact same location/manner and finally if the new battery has less voltage sag than the first battery your motor/ESC could be delivering more power/thrust as well as a greater torque reaction. A revision of the thrust angle slightly downwards may make the possibility of differing thrust causing trim changes.

They do fly well and predictably when sorted and I often launch mine at half throttle and watch it fly straight and level from launch height, (until I open the throttle and point it vertical that is):rolleyes:.

Differences in pitch and roll responses can be adjusted by tinkering with mix ratios if you are brave!

Have fun!
 
#25
Sounds like you almost have it beat! Congratulations are in order!

The change in roll and pitch trim can have a number of tiny causes. Upon landing you need to make sure that the landing did not change the alignment of the winglets. The CG might have changed slightly if the new battery was a different weight or not installed in the exact same location/manner and finally if the new battery has less voltage sag than the first battery your motor/ESC could be delivering more power/thrust as well as a greater torque reaction. A revision of the thrust angle slightly downwards may make the possibility of differing thrust causing trim changes.

They do fly well and predictably when sorted and I often launch mine at half throttle and watch it fly straight and level from launch height, (until I open the throttle and point it vertical that is):rolleyes:.

Differences in pitch and roll responses can be adjusted by tinkering with mix ratios if you are brave!

Have fun!

Just got my new props (non slowfly props) so hopefully should see some speed increase, i also upped my throttle channel limits. Im using a simonk ESC (it was super cheap) which cant be calibrated. i was running at 120 and increasing to 140 there was definate increase in power, beyond 140 couldnt tell.

Also got a turnigy 1000mah battery to try. My last flight was just under 5 minutes and saw the battery coming down at 12v resting. pretty decent. Maybe with 1000mah i could see 10 minutes of gently flying. There pretty inexpensive aswell at 5GBP each.

Ill look into adjusting the mix, i could probably dial back the eleavtor and give more aileron
 
#26
Sounds like a plan.

I would recommend using a strip of fibre tape alone the LE in case of rough landings!

have fun!
I should have done that today before going out!!!!! I was out testing after moving the CG slightly back and all was going well. Still needed a fair amount of up elevator trim for level flight but it was diving better (looiked like it was maintaining a dive) it also was gliding very well. I cut the power and just let it glide, and glide and lgide, it slowed right down couldnt tell any signs of stalling. it got to the point i thought better put the power on incase it just suddenly drops.

So i guess teh CG is pretty close.

unfortunatly during a very tight turn 6 feet of the ground i got orientated pointed down, and when i pulled back to pull up nothing happened and it nose first into the runway at the field.


This didnt make the wing fold but instead ripped 1 half of the right wing of. Big tear right through the entire wing even spar.... It could be repaired but this would be a weak point and also make it heavier on one side.

So ive printed of the plans to make V2. this time with the paper removed and wingtape covered on 1 side. this should hopefully make a much stronger and lighter arrow. With the 1000mah battery i was sitting at arond 330g, although it did fly very well and despite the extra weight would fly very comfortable at slow speeds (slower than my yak 55 profile)

Hopefully by the end of the day ill have a complete model. No damage to the power pod or even the prop which waas standing the back of the plane up (prop facing down and touching runway)
 
#27
Just got done doing my 2nd mini arrow.

i removed both sides of the paper (except for the spar didnt see much point although probably coul dbe an extra 10g saving). Ill get pictures up later but it look really nice! Ive done it in 2 colours, red on top and purple undearneath. didnt follow the build videos so a few hicups but easily fixed.

One issue i have is my electronics pod seems to be ever so slightly narrower and its a real struggle to get my 1000mah battery in there... heard a crack when i pushed it in which i assume was glue somewhere letting go... Might go over th seams again with the battery inserted and run a strip of filament tape (before inserting the battery) and hopefully the walls of the electrincis pod will just squeeze.

All ive got left to do is put on the control horns on the elevons and put the vertical stabilisers on.

Good news is that weight with electronics is 270g!! And thats with the 1000mah battery :) So say an extra 10g once the verts are on!!!

So removing both layers of paper and using packing tape with west foamboard will get you to the same weight, its a fair bit of work though but if you use coloured packing tape can look really good :)

Ill get it funished up tomorrow and hopefully a flitetest.


It feels really solid aswell!! theres much less wing flex and im sure that the tape will help prevent tears, although it seems that when i crash it has to be something solid....
 
#28
Getting Frustrated!

So as nice as my arrow looked something must not have been right.

It was a bit windy today but didnt think it was too much for the arrow to handle. the first hand launch the wing did a roll to upside down as it flew forward, aborted the launch and it bounced of the long grass.

2nd launch it started to do the roll but then started flying straight and then started climbing???? flew around for a few circles, but it was flying very strange, kept nosing up. dialed in some down trim until i had none and it still trimed. it was flying very unpredicatbly.

Landed confused, moved the battery back slight. it launched a bit better but it was still wanting to climb but flying a little better. I checked the cg before i left and im pretty sure it was almost spot on with the battery all way forward.

So decideed just to fly around, it didnt feel very stable but that might have just been wind. was doing figure 8's being carefull to miss the trees when suddenly the arrow was pointed nose down with the bottom facing me. it was only maybe 15 feet up so rather than power it into the ground trying to save it, just chopped the throttle and let it fall. It hit dead on the nose.

No probolem i though the nose will just be bashed a bit. NO it tore of a wing!!! broke just infront of the hotglue seem between the wing and the electronics cabin!

Getting really frustrated as it seems that it is not standing up to well to nose impacts at hardly any speed.
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#29
Whilst you get the wing sorted out I recommend that you get your piloting skills in tune as I did by building one of these.

https://www.flitetest.com/articles/tinywing

I scaled mine up to 800mm Wing span and if flies a treat, glides like a dead pigeon, and is so robust that I still have my very first version and it is going strong without any repairs to date. With chamfered LEs and a line of fibre tape is is my flying tank.

Use it to get the feeling of various setups and CG points as well as hours of airtime which you can then transfer to your Arrow.

Remember the Expo and be advised that it does not loop very well but otherwise it is a hoot. So far mine versions have used motors between 100Watt and 250Watt without real issue apart from balance and the higher power versions can climb vertically almost from launch,

Just a suggestion!

have fun!
 
#30
I dont think its a piloting issue although i havnt flown in over 12 years ive been flying helis for the last years and before these crashes i was flying around doing circles and figure 8's and even stall turns. The first time i put it down to the wind, but the 2nd time doing the same thing has me leading to believe its a problem.

Maybe a control horn gave way, the first time it happened even pulling up didnt do anything. the 2nd time.... I did notice 1 of my control horns was loose although that could have been from the crash...

Ill pick up some more foam board and make 3, to make things simpler ill just do the wing in 1 colour and the pod and stabilisers the other. then use filiment tape for reinforcments.
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#31
I dont think its a piloting issue although i havnt flown in over 12 years ive been flying helis for the last years and before these crashes i was flying around doing circles and figure 8's and even stall turns. The first time i put it down to the wind, but the 2nd time doing the same thing has me leading to believe its a problem.

Maybe a control horn gave way, the first time it happened even pulling up didnt do anything. the 2nd time.... I did notice 1 of my control horns was loose although that could have been from the crash...

Ill pick up some more foam board and make 3, to make things simpler ill just do the wing in 1 colour and the pod and stabilisers the other. then use filiment tape for reinforcments.
After reading that you have ripped a number of the same design I did a quick scan of other crash posts and there seems to be a common point of failure during a crash event on the design.

Where the propeller cutout is there are 90 degree corners and most ripped wings have one of the corners as part of the failure. I suspect that on impact the mass of the wing is trying to pull the wing forward whilst the remainder of the aircraft becomes suddenly stationary. This relates to great forces which are released in the structures weakest point, the 90 degree cut corner.

To improve the structure for further crashes I recommend that you consider making the 90 degree corner a curve instead and to add additional rip resistance you could add some CF or skewer reinforcement across what was the corner ot divert the forces involved.

This might add a little additional weight but it will reduce the need to build a new plane every time you land roughly.

Just a thought!

Have fun!
 
#32
Ill add some pictures so you can see (i did try but had issues trying to upload photos from my phone)

but i think you are right. Ill try adding some reinforcement to those areas. Im not so sure that the CF tape is any stronger than paper, infact it might actually be slightly weaker. I compared my original wing with the new wing and it seems the paper is much stiffer.
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#33
The CF or skewer reinforcement I was considering was a groove or channel dug across in front of the weak area and then filled with possibly epoxy and the CF bar/rod or the skewer buried in the glue. Wipe up the excess and when dry cover with tape.

have fun!
 
#34
I forget to run a bead of glue in the hinge area of the leading edge... Thats where some of the weakness is and guess what, i did it again on my 2nd wing.

Ill need to run filament tape over the outside a few layers thick. That should stop it splitting.
 
#35
Right i think were good for V3.

Just about got the finishing touches done before work. Leading eddge has a strip of filament tape along it. The rear secions on the inside has a strip of tape aswell as the outside. IM tomorrow before the mainden going to run a strip that raps round the back edges. Should should reifnorce it enough if it does happen to have a nose inpact should stop the wings tearing off. BUt hopefully that shouldnt happen.

Also sorted out the slop in the control rods, the hoels in the control horns are slightly too big and on 1 control surfface there was a fair amount of slop. I guess the elevons could ave been flapping and it resulted in loss of control or loosening a control horn.

As long as the wind is good tomorrow ill test fly it (and get a video so you can actually see it)

Hopefully this one will be flying alot better, things look alot more symetrical, both elevons when set by the guage look the same (the previousl arrows even though the gauge showed they were both same, one looked higher than the other)

The only remaining issue i have is 1 elevon is moving more than the other.
 
#36
Just put in an order to Hobbyking for foam. Also ordered a few of there really cheap cract knifes (x blade something £0.36p!!) as ive been using bare stanley knife blades which are a bit big and awkward. carbon rod and clevis for stiffer and easier control rod setup.

Should be here in a few days, ill make up the plans ready for the foam and batter out a couple spare wings for while im away. I should be able to get 2 or 3 wings worth of parts cut out in a few days by using the plans t cut out 1 and then use the foam cutouts as templates :)

No maiden on my 3rd wing yet not risking it in the weather we have, we are ont he edge of a hurricane at the moment, yesterday was 50mph winds. today is 15 at the moment which is too much. Really annoyed, yesterday i didnt take my wing with me as the winds were bad, and when i got to the place i was going to it went totally calm!

Need to pickup somehook n loop tape, im wondering if the sudden pitching down was the battery moving back in flight causing it to suddenly go tail heavy.
 
#37
Got my HK foamboard. Came relativly undamged, the 2 outside sheets had a few dents in it and the sides aswell but no cracks or splits.

Ive made 2 wings with this stuff so far, it feels lighter. No electrics weight is 100g with packing tape on 1 side. so guess 150g withj battery, 180 with motor and ESC and then 200g once servos wires and rods are on. seems awfully light.... or am i being over optomistic.

So ive got 3 mini wings now, (2 are spares)

Pixtures to follow
 
#38
Could have sworn i added pioctures yesterda....

anyway had successfull flight today! No trim issues, a few clicks down elevator as it was wanting to climb a little that was it. All setup like the previous. elevons set with reflect using the gauge, this time however both elevons actually looked like they were at same level, not like before where 1 looked higher than the other.


flew for just over 6 minutes and battery came down at 11.7v :) i wasnt flying fast mostly just over half throttle. i gave it whelly once just to here the nose but didnt want to crash it.

This one is alot twitchier than the previous ones, i was flying it like a helicopter just tiny stick movements, so im going to dial in some Expo and try flying also with low rates. It still has a tendancy to rock its wings randomly, i had someone who is an experienced pilot who and he says some wings just fly like that.
 
#39
Had a great morning with my mini arrow yesterday. Got to compare my old 850mah batteries with the new 1000mah, definatly way better with the 1000's my 850s must be getting tired.

Loving the flight times with the 1000 but can feel the extra weight. i increased my timer to 7 minutes, landed and the battery came down at 11.8v so launcehd and came down after 2 minutes, 11.5 i then dceided to practice quick landings by launching and coming straight back in effectly just 1 circit, take of come round and land straight away. after several of those i was down to 11.4v. So easily 10 minute flight :)

Unfortunatly i gave it a bit of a hard landing and split the seam along one side of the pod. several strips of electrical tape as a brace and it was ready for more flying. flew maybe 4 or 5 full batteries. No problems evem with it taped up. Iver fixed it now that im home ready for the next flyable place.
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#40
Congrats, Sounds like you might have it nailed!

You will find that they really come alive with speed and plenty of expo!

Have fun!