Gryphon

This post will be edited later to point to various info in thread.

iamman711

hi,

My Stryker is all stock but i reinforced the airframe with clear duck brand packaging tape all around except the middle underside where I reinforced/stylized with blue and neon orange duck tape. I added a servo in front of battery bay to control steering on nose landing gear. (Fixed [8D]) landing gear is heavy duty, not very aerodynamic, purchased at hobbycity per a previous post of mine. I opted for this heavy duty landing gear because when i was about to put in some 2mm wire retracts, yall advised me its too wimpy to handle the stryker landings. all in all my Stryker tips the scales at 32.9 oz. Some of the extra weight comes from gorilla glue securing front nose gear mount, three thin (useless?) strips of carbon fiber embedded from the belly and reinforcing the middle of the plane , and 12 small neodynium magnets securing the removable nose, and also the battery hatch. Stock motor, stock prop, stock 11.1v 2200 mAh lipo. Center of gravity is very nose heavy.

Its been sort of windy in southern california and i am waiting for docile weather to maiden my plane. Can you experienced pilots tell me if my plane is too heavy for the stock electronics, what to expect for this nose heavy plane, and do you think it will still glide well especially on landings.

Check out ma pix!

jumper666

iamman711, yes, that is heavy. Have you a watt meter? You can get some idea of performance you might expect if you can determine the power the motor/prop is producing. Here are some suggested power needs:

50 - 70 watts/lb = min for light park flyers
70 - 90 watts/lb = trainer and slow flight
90 - 110 watts/lb = sport aerobatic & fast scale
110 - 130 watts/lb = advanced aerobatic & high speed
130 - 150 watts/lb = light 3d and ducted fans
150 - 200+ watts/lb = unlimted 3D

Looks as if you will want at least 200 watts.

iamman711

Hey jumper, cool i've never before seen the relationship laid out like that. i bought an eflite power meter but it didnt come with any plugs so its been collecting dust as i haven't decided whether to stick with the blue EC3s or the dean ultra plugs. can you guys help me make my mind. leaning towards ec3 as i own all parkzone products so far like the parkzone charger, 3 lipos, etc. i figure if it aint broke, dont fix it so i didnt bother to swich over to deans but then again i dont know what i am missing.

the good thing about my current landing gear is that it is removable. the nose gear screws off, and the rear gear is secured with clear packaging tape and velcro.

jumper666

I bet someone will pick apart using the watts/lb suggestions, but they are just that....suggestions.

My preference is Deans on everything.

Gryphon

Here is a way of picking apart some numbers.

Well, more like analyzing numbers, etc...

I took the data for the 3S packs from Don's site and tried to figure out a way to come up with an equation.

http://www.donsrc.com/cart/index.php...d&productId=12

I decided to see if I could find an equation that would give me some value, if I had a second value.


So how do I get RPM if I know amp draw?

(For 3S in the 23A to 34A range)

RPM = - 347.2 X (Amp) + 32389

Test for 27A: RPM = -347.2X27+32389
RPM = -9374.4+32389
RPM = 23015

Actual RPM from site = 23000 RPM
Difference of 15 RPM

***No all numbers come out as close. Equation results give from 320 RPM too high to 220 RPM too low. As an average those values are within 120 RPM which is not bad at all.

____________________

Here is how you can do your own numbers:

In Excel spreadsheet line up Amps on left column, line up corresponding RPM on next column.
Highlight the whole thing and then click on scatter chart to get a plot.
On plot double click on the points to get them highlighted, then right click and choose add trend line, see which one of the options comes out closer or close enough with the simplest equation.
Make sure to check the box that will display equation while still in the trend line menu.
In the case above I chose linear because things lined up pretty well, otherwise I guess I would have chose 2nd or 3rd order polynomial.


Gryphon

BubbleGum

Hey Man,

Nice work. One word of caution... You have the main gear pretty far forward so there is a possibility that the prop might hit the ground on take off. Have you seen at what angle nose up that the plane of the ground crosses the circle of the prop? That is, turn the prop so it is oriented up/down, place the plane on a flat table, then pivot the plane on the rear gear and note the angle when the prop just touches the table. As long as you don't get near that angle on take off it should work well.

I forgot to ask, or if I did forgot the answer. What kind of field are you going to launch. Dirt or pavement or?

~Bub

clovus

Hey Guys, You have probably answered this 100 times before, but for those of us on dial up (gasp!) I would take all day to find the answer.....

When you are setting up the Stryker which way does the prop face, writing forwards, or writing facing the back?

Cheers

clovus

Gryphon

Only the stock F-27B's push on type prop has the numbers facing back.
I don't know the stock prop that comes with F-27C motor.

Almost all of the regular props have the numbers face forward.
The props turn in the direction that has the smooth (thick) edge of the prop cuts through the air first.
If standing in front of plane (at the nose) and facing the motor, the prop will be turning counter clockwise.
If standing behind the plane and looking forward, you will see that the prop is turning clock wise.

Example APC E 6X4

___________________

Very few props are called "PUSHER" props they still have the writings face forward, but are meant to turn in different direction that above props due to having reverse pitch (the prop is twisted the other way).
Again you will see that the smooth wider edge of prop will be cutting through the wind first.
Some of those will be like APC EP 6X4. (The P means pusher and cost more than prop above).
____________________
For a twin, ideally you would want one of each prop of same specs turning different directions.
(1) APC E 6X4 and (1) APC EP 6X4 each turning in different directions to cancel torque effects.
____________________

Strykers have a pusher motor so why do we usually put on regular props even though our motors are mounted in rear?
Because we have a LOT MORE variety to choose from, availability, and price.

With brushless motors we simply control the direction of rotation with swapping any 2 of the 3 motor wires.



Have fun,

Gryphon

dslusarc

One way of estimating power needed on a prop is to use the cubed relationship. If I have a prop spinning 25000 rpm at 300 watts, to spin it 29000 rpm you will need: 300 watts * (29000/25000)^3 = 468 watts minimum to spin the higher rpm. Generally though you will need moore watts as the motor efficiencies drop as the watts get higher, but it gets you in the ballpark. Also thrust goes with RPM^2. So if you have 16oz thrust at 20,000 rpm at 130 watts, then go to 23,000rpm, expect 16*(23/20)^2= 21.16 oz of thrust and 130*(23/20)^3= 197.7 watts to do it.

Don

Stryker_Viking

iamman711

I helped a guy the other week at the field with a similar setup as yours, this is what I had to do to make his Stryker balance correctly:
* Removed all duct tape in front of COG-dimples
* Replaced the frontwheel with a Light-Weight alternative that I had laying around
* Replaced his stock 6x4 prop to a 5.5 x 5.5
He later used spray paint to the areas where the very heavy duct tape had been...

Good luck

Stryker Viking

Stryker_Viking

New experience...

Though somewhat out of topic I still feel the need to share this with you all...

I maiden my Zagi 5C that I built quite a while ago down at a extremely cool and steep sloope down the coast the other day.

For you who don't know about this plane: It's a 48" flying wing made out of a extremely strong spongie type of foam (EPP) reinforced with CA, only spray glue is used and the whole thing comes together very quickly. It can be motorized but is generally used as a slope flyer...

Being a total virgin in this type of flying I prepared myself and tossed the wing over the edge, and thats when the magic started. It just took off and quietly climbed and climbed without any input what so ever... To make a long story short, 30 minutes later the struggle started to get her down, that's right - the problem is NOT to get this type of bird up, it's to get them down...

It was a blast, and I can highly recommend it as a complement to all Stryker Pilots of the Dark Side, it's great practice that will enhance your skills, and after all our Stryker started as a slope glider they say...

Will now try my motored setup next time.

Cheers to you all

Stryker_Viking

iamman711

thanks Bub,

When the plane pivots on the rear gear the rear edges of the swept back wing hit the table before the circle of the prop even comes close. I played around with the placement of the gear to make it back more or forward more and I decided where it currently is because its right at the center of gravity and should facilitlate takeoffs. the nose gear is sort of forward and the reason i put it there was simply because i wanted to put the servo above it to control steering and thats the best place i could find without thinking too hard.

You never asked, i dont think, but I plan to fly on pavement, and on grass. the landing gear is really high so ground clearance is not a problem.. i hope. I plan to stay away from dirt given that the rear placement of the motor makes it susceptible to dust/debris I am guessing. don't want to take the chance.


thanks Stryker Viking,

What happened to your friend's plane did he even have the guts to maiden it.. if so, what was the result? My big question to you is about nose-heavy planes. I heard that if you fly nose heavy its no problem. if you fly tail heavy, you fly once.
So given that my Stryker is nose heavy (assuming that carving out the foam in certain places did not mess up the center of gravity of the plane at the COG dimples), will this present a problem or what?

I might remove the duck tape because i am positive that it adds a lot of unnecessary weight to my plane, although removal probably won't affect medial balance (nose-tail heaviness). Do you think the clear transparent duck tape i covered the rest of my plane with adds too much weight as well? it is the duck brand packaging tape and i have it all over the place on my Stryker. (Only a single layer) If I remove the heavier duct tape along the middle of my Styker, should I replace it with clear transparent packaging tape like the rest of my plane or can i use strapping tape which is heavier. I just wanted to make my Stryker strong in case i crash it hence the duct tape.

Last question is about the 5.5 X 5.5 prop. So it is shorter than the stock 6 X 4 prop but has greater pitch. How does the 5.5 X 5.5 prop compare to a 6 X 5.5 prop? Just curious, and do you think i can upgrade to 6 X 5.5 with no problem.

*just for clarification as it gets confusing:

duck tape = clear packaging tape by duck brand, which i used everywhere on my plane except where I used duct tape
duct tape = colorful, heavier duty tape also by duck brand, which i placed on middle of plane on its underside.

...

Thank you everyone.

iamman711

Stryker Viking, maybe if you modified your Zagi with flaps you could bring it down easy... just a thought.

Btw, how do you make those digital backdrops in your uploaded pictures, not this most recent one but in the past. Do you just use Adobe photoshop?

BubbleGum

Sounds like you know what you are doing and you're good to go!

~Bub

Gryphon

dslusarc,

I wanted to thank you for those two formulas.

The will come in handy for quick calculations to get us close to our goals faster.

They don't seem too hard to memorize either.

It would be great if some of us remember to post those 2 formulas a couple more times on part 7, so it becomes 2nd nature for us and also to teach something to the new folks who will be joining us later on.



Have fun,

Gryphon

iamman711

Wuttup all,

I just got home from flying my Stryker for the first time. I had three flights on 3 batteries and everything went smooth, luckily. This bird was so tame because it was so heavy and underpowered that it couldn't even do a loop without first diving then doing the loop. Rolls were simple and inverted flight looked good. I had D/R and Expo settings at 85% and 10%, respectively for both aileron/rudder (for fear of the stripped servo issue others have reported).

I took off on asphault and landed on grass, which was a little wet. It took about 30 feet to take off. Landings were smooth as I simply idled my Stryker to the ground with a little flare at the end. I needed a lot of room to land it as it just floated all the way down.

iamman

Gryphon

iamman711,

I'm glad your plane is handing the landings so well. I really like the looks of your landing gear....how about close up pics sometime?

The pair of wheels in the front looks fantastic. It appears like your design proved itself.


Correct me if I don't remember right. You placed the rear landing gear close to the stock C.G. points, and then you have the front landing gear and the servos far forward....again let me say that it looks great.

So would that make your Stryker nose heavy? (I mean C.G. forward of stock points)
If so how much, 1", 2", etc....?

You could reduce that amount by pushing the battery further back and you might have already done so.

If C.G. is too far forward and when combined with low amount of throws that could be the reason that you are not able to perform vertical loops.

Why be in fear of your servos…it is just a matter of time before you give up and change a pair of servos and connecting rods…sooner is better and you will not have to say to yourself: “Why didn’t I do this sooner.”

Also imagine being in trouble and not having enough throw to pull out…..seen that happen too.
_____________________

I was not 100% sure of your trans settings.

If you want better feedback, in case we can think of something, try the following:

List your D/R and expo and travel adjust and throw something like this:

Travel adjust aileron 100% , elevator 100%

Throws on high rate: Aileron Xmm up, Xmm down ..... Elevator Xmm up, Xmm down (assuming both sides are same).

High rate: aileron 100% expo X%, elevator 100% expo X%
Low rate: aileron 85% expo X%, elevator 85% expo X%


Have a great weekend,

Gryphon

iamman711

thanks Gryphon,

Here are some close-up shots of my landing gear. They have spring suspensions btw.

i made the landing gear similar to most ROG setups. Since the weight of the plane is more toward the nose, the landing gear supports mainly the front of the plane. The CG is shifted roughly 0.5 inch from stock point. Pushing the battery back is a good idea but I first need to upgrade my ESC to one that is hopefully slimmer and can fit closer to the motor without me having to carve out more foam (i don't like to carve foam that much).

Travel adjust aileron 85% , elevator 85%

Throws on high rate: Aileron 3-4mm up, 7-8mm down ..... Elevator 3-5mm up, 10-11mm down. Curiously, both sides are not the same (so i gave you the range). Any idea how to fix this..? Also, my elevator up is alot smaller than elevator down. Repositioning on pushrod on control horn did not seem to fix.

High rate: aileron 85% 10 %, elevator 85% expo 10%
Low rate: aileron 85% expo 35%, elevator 85% expo 35%

edit: added one more pic from hobbycity.com for a better closeup without plane.

Gryphon

iamman711,

Let’s start with a couple/few things first.

****Read everything and compare to your trans before doing any work or changes.

***Since you have already flown your bird note position of each control surface with system on so you can set it back to same position when finished. For example measure from the top of inside edge of each elevon to the top of foam tab in mm and record for each surface.


Little bit of basics:
Trans on Delta configuration
Make sure both servo arms are same length and the rods connect to same hole on each arm.
Make sure both rods connect to same hole in control horns.
Usually best to have rod as high as possible for more accuracy and consistency and less slop. So I try and use highest hole on control horn and then use a hole on servo arm that works for my needs.
Make sure there are no binds at full deflection as far as servo arms or rods making excessive contact with foam. Also move the stick in all4 far diagonal corners and check both servos and rods for bind. In far diagonal there is more control surface deflection and better
__________

1)With zero trim on outside of trans, you need to make sure that the servo arms are perpendicular to the direction of travel.

If your servo arms are leaning too far, then that could be one cause of your moving surfaces not moving the same amount. Place them on the closest spline so they are perpendicular.

***If you want to be closer, then use 20 steps or less of subtrim inside the programming to get the servo arm perfect after you place it on closest spline.
Before changing subtrim, experiment with one spline forward and one back and see which is closest and use that.
***Subtrim is different than trans trim on outside of case. After setting subtrim, do not change it again.

__________________________

2)The travel adjust for each ch actually has two adjustments for each ch.
Aileron L100%, R100%

Elevator D100%, U100%

When you set yours to 85% maybe you only did one of the two numbers on each ch.

When you get into that menu, and move arrow to the desired ch, you will have access to one direction of travel of each Ch, to get to the other second number of each ch, you need to move the stick.

For example if on elevator ch, when you change numbers the arrow is moving the U%travel, then you need to hold the stick up(down elevator) to change number for the D% travel.

Same thing for elevon, you will have to move the stick to the other side to change 2nd number as in L%, versus R%.
________________________

When finished change the length of the rods by twisting the clevises to place the elevons in same position as you started so your plane will stay trimmed for flight.

(During a build, I install my control horns so the holes are right above the hinge line.)

***Re-measured your throw like this: WHILE ON HIGH RATE

Left control surface:
Aileron input only UP deflection of surface: mm Down deflection surface: mm
Elevator input only up deflection of surface: mm Down deflection surface: mm

Same measurements for right control surface:

Total of 8 measurements On High rates.

***You can set travel adjustment on 100% for all 4 numbers in elevator and aileron and later lower the throws in D/R to get your desired control surface deflection. (Not required).
_____________________________

I assume you didn’t mess with DIFFERENTIAL option or any other mixes except rudder adjustment for your front wheel.


Tell us what you find,

I hope I didn't screw up the write up above with a brain F_rt, feel free to ask for clarification.
You already have a better way of getting a hold of me. Try that too.
I hope you liked that 7 meg video file I sent you. Lots of touch and goes on that Stryker.


Gryphon

BubbleGum

Hey Man. Congrats.

Glad your maiden(s) went so well. You did your research and your homework and it paid off. I am impressed. That's a lot coming from a guy who has invested some 27 landing gear iterations myself.

I suppose you will be looking for more power now.


~Bub

Brazman

Speaking of more power . The club near my house had a competition meet on this weekend and I went down for a bit hoping to get to test my stryker on a bigger field than the one I usually fly at. They were running a competition when we got there so we had to wait around for quite a while. After the comp they had a free flight session and I got ready. Since we had limited time I set it up immediately with the heavy batteries (2000+watts!!!). I had intended to fly the light set first. I put on the 6x5.5 apc and did a quick control surface test and handed it to my friend. I gave him instructions about what i wanted, 20-25 deg up and a good hard throw, no run or anything. I throttle up to half throttle and gave him a nod. He threw it perfectly and I eased back on the stick and off it went at about 45 deg climb out very quickly at half throttle. I flew around a bit I half throttle then backed off to get an idea of who was in the air and where I would do my first speed run. One of the guys from the club had what seemed to be a fairly fast gasser mustang in the air and looked like he was lining me up for a race. We turned onto the main strip and he went full throttle I waited a bit and let him pass me. Then I went full throttle as well..a few seconds later I was blowing past him at an insane speed with a few laughs and oohh's from the crowd. Next thing I noticed was that I was literally hands off...no control input whatsoever. I backed of and turned around and cruised back past the pen. Next thing I noticed was that I was still on high rates and it felt incredible. Razor sharp handling, very fast rolls and very precise. I did a couple more announced speed passes on the cross strip ( there was only 2 other planes in the sky at this point) then ambled around playing for a while with some full throttle verticals and such (at the limit of my eyes in seconds) and then waited for an opening to land. I came in for my approach and thought I was doing well until it got close and I realised it was still very hot. I realised this just as i touched the ground but I eased back on the stick again and throttle up...a touch and go on the first flight with the big packs!! I came around again and did some "space shuttle" turns to bleed speed (i'm sure these have a real name but I don't know what it is). This did the trick and I touch down and skidded (quite a long way) to a stop. Went and picked up the plane and the motor was cold. I brought it back to the pen and pulled the batteries out and they were very cool (probably 40 deg celcius). This is very significant as I have cut no cooling holes yet and the factory ones are blocked with filler and glass. The flight went for about 10 minutes all up. It took me 30 minutes to get back to the marquee from the pen with all of the questions. I think I might name the plane rockstar lol.

I forgot to give you details on my throws. High rate throws are 12mm all round iwth 50% expo. Seems excessive for 2" control surfaces I know but it works beautifully.

My friend may post soon..he can explain what happened to the video

KegRaider

Hi Brazman,

Sorry about the no video....I'm dreadfully embarrased. After I looked back at you from the throwing position to get the "Ready" nod (you could have reminded me to pack some ear plugs!), I had my left hand holding the nose, and my right hand was firmly gripped on the little stips of sandpaper you had glued. The nod was given, so I held my breath, rocked back towards my right, pushing the nose back with my left hand. I hurled this heavy plane like an ancient spear towards the mountain top in the distance.

I counted my blessings (and fingers) after the throw that it went so smoothly! I then jumped the barrier wall to where the pilots stand, and grabbed my video camera. I pressed the record button and proceeded to try and follow this insane machine through the skies! It was very hard to do, as my hands were still shaking from the adrenaline rush I was receiving. Unfortunately, my shakey hands didn't press the record button long enough, so i was just using the camera as an electronic monocular I was having trouble keeping up with the Stryker on the high speed passes anyway. I just can't twist that fast!

He's right about the 30 minutes to get back to our car. Even I was asked questions about the 'Electric' plane, and overheard people saying "Was that an electric plane?"....."I've never seen an electric plane go so fast!"

Hopefully soon Brazman, we'll have something to post on youtube

> KegRaider

Gryphon

Brazman,

Hey there buddy that is fantastic news. I’m so glad for you. I totally know what you mean when people ask: Iis that thing electric (in surprise), or say: That thing is not electric. ……LOL…

Guys don’t sweat the video, there will be other chances…..

BUT I want to hear about KegRaider.
______________

KegRaider. Welcome to the thread.

Do you fly R/C/ planes?

If not consider starting with the likes of Aerobird 3 from hobby zone then get a Stryker for your 2nd bird. With your friend’s guidance that is easily do-able.
http://www.hobbyzone.com/rc_planes_h...aerobird_3.htm

Brazman can tell you all about FMA Co-pilot.


KegRaider. DARK SIDE is calling you. What does that mean? Just ask Brazman.


Thank you both for your posts.



Gryphon

iamman711

thanks Gryphon,

As usual, I appreciate your support and helpfulness. I didn't even realize that travel had two sets of adjustments and you had to move the stick to access it. To think I flew with such an incomplete setup... lol. On closer inspection ( i don't know why i didn't realize earlier), my right control surface is warped. Having never exposed my plane to excessive heat or sunlight, this problem probably existed since the beginning. Nothing some trim coudn't fix. Replacing with balsa is the next obvious step.

I am trying to fix my plane as i flew it a second time in the evening and crash landed my bird. Was landing and contacted the ground at a rocky, unlevel area between asphault and grass. it is hard to describe but basically it was the ugliest landing ever, causing the plane to jump back into the air and lose the right landing gear. I aimed for asphault and barely missed it by literally a couple inches. Lesson I learned: come in for the landings lower by using more throttle control, rather than idle the bird down rather steeply. my bad. it was kind of dark at the time.. no, that's a pathetic excuse.

the result: landing gear broke in two places, at the plastic base of right rear landing gear and at the plastic nose gear mount. Easily fixed with gorilla glue. The carbon fiber strip along the middle of my plane was frayed a little where the nose gear's aluminum pole (for lack of a better word) jutted and tore into the foam. So with a gap/hole in the foam behind the aluminum pole, I have to find a way to help secure the aluminum pole so the nose gear can be rigid again. i plan on using a dremel to cut the right sized whole in a piece of thick plywood and secure this piece of wood around the nose gear where aluminum pole meets the foam.

All in all, not a bad crash. The heavy duct tape minimized damage to the foam afterall. Very coincidentally, i ran into an F-27C Stryker flyer as I was getting ready to leave the high school i was flying at. I got to see how a stock f-27c flies with no extra weight.. it went a little bit faster and a lot higher than mine. then i flew mine again and the rest is history.

Measuring the throws... It might be best if I first replace the warped control surface with balsa.. something I am not too experienced with and it could take some time.

Yes thank you that video is probably the best video i have seen on Stryker landing gear. I'll have to make my own video some time to give other people alternative ideas.

-

thanks Bub,

My first flights were rewarding. I enjoyed all the work i put into my first Strkyer. I'll have even more fun as i go deeper into the dark side...