HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 09, 2012, 09:01 AM
Registered User
FlyBoy20's Avatar
United Kingdom, Wales, Swansea
Joined Aug 2012
513 Posts
Quote:
Originally Posted by RWData View Post
Fly... It could even be too much expo dialled in, try about 50% and see if your elevon's pick it up a bit more.
Reading others comments I decided as I'm inclined to wang the sticks in panic-stricken tree-alert mode, I should go for Low - 40% aelerons and 50% elevator with 15% expo, and High - 50%/60% with 10% expo. Dunno if this sounds right?

Quote:
Originally Posted by RWData View Post
Anything outside of stock... make sure you are not stressing any of the electrics if you 'prop-up' as you could end up with a short final flight for this model.
I'll check the 6x5 on the wattmeter first to make sure things don't get too hot. Anyway, I'm not looking to break any speed records at this time - just want to cruise around for a while on part throttle and make nice landings. I thought I'd work my way up to the fancy stuff very gradually...
FlyBoy20 is offline Find More Posts by FlyBoy20
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 09, 2012, 09:22 AM
Wake up, feel pulse, be happy!
C₄H₁₀'s Avatar
United States, AK, Fairbanks
Joined Aug 2009
12,377 Posts
Quote:
Anyway, I'm not looking to break any speed records at this time - just want to cruise around for a while on part throttle and make nice landings.
The ESC will actually run hottest at partial throttle settings (~50-75%), and then there will be short spikes of current significantly higher than what you see on the meter even at full throttle. This is one of the biggest reasons to leave a solid bit of overhead on ESC ratings unless you plan to just fly at full throttle all the time. Generally it's safest to draw no more than ~80-90% of the ESC's rating in static testing, which will combine with in-flight unloading to ensure that you have ample headroom .

There are mixed camps on prop brakes. Some people say it's easier with the brake on so you can bump the throttle to position the prop where you want it for landing, while others say you're better off letting it windmill. Personally, I've never found either method to be significantly better. My preference is the windmilling prop since trying to position it with throttle bursts on some planes can mean the difference between landing and going around again.
C₄H₁₀ is offline Find More Posts by C₄H₁₀
Reply With Quote
Old Dec 09, 2012, 09:25 AM
PowerTower
RWData's Avatar
United Kingdom, England, Bristol
Joined Aug 2009
981 Posts
Fly, I'm guessing you mean %Rates then %Expo. Try setting 50/75% rates and 50% expo on all. That way you soften the stick around centre and still get 50/75% on surfaces at full stick. It begins to sound like not enough air-speed with too much elevator on take-off. Double-check your prop, it should have the prop-size in raised numeral clos ro centre of prop on one blade. This always faces forward regardless of pusher/puller config. I think you would be wise to get stock settings to work before you start playing with different prop's, the only thing they might do at this stage is give you a faster lawn-dart !
Before you launch to oblivion, do some bench testing...
Static (prop removed), move the elevator stick down, how much deflection are you getting at full stick (measured at extreme tip of TE) ? Now same again the other way, and again with aileron input in both directions. 8-10mm would be quite enough for a new(ish) pilot. If you get this with 50% rates, then 75% rates will be something like 14-16mm, surprising what that small amount can do (50%). Full beans off the mark is the way to go, with a 'wing-man' launching so you are on the sticks straight off. Keep at it, this will be somewhat more 'exciting' for a newb than a high-wing trainer, so be prepared for a bit of disappointment. A good option would be to build yourself a simple delta, which although a tractor prop design will give you some feedback about how an elevon model flies, but the simple delta can do it slower and give you a much better recovery time
RWData is offline Find More Posts by RWData
Reply With Quote
Old Dec 09, 2012, 11:00 AM
Rocket Programmer
jasmine2501's Avatar
United States, AZ, Mesa
Joined Jul 2007
25,355 Posts
It is basically a Funjet, same design... these should be pretty easy to launch, but there's some things to watch out for... don't throw it super hard, smooth is more important. It needs to leave the hand without any twist on it, perfectly level, nose slightly up. I find it's best to launch power off and throttle up smoothly - SAFETY first!

Proper Stryker Launching Technique (1 min 0 sec)
jasmine2501 is offline Find More Posts by jasmine2501
Reply With Quote
Old Dec 09, 2012, 03:08 PM
Registered User
FlyBoy20's Avatar
United Kingdom, Wales, Swansea
Joined Aug 2012
513 Posts
Quote:
Originally Posted by RWData View Post
Fly, I'm guessing you mean %Rates then %Expo. Try setting 50/75% rates and 50% expo on all. ...
I had wondered should I try it the other way round...?

Quote:
Originally Posted by RWData View Post
A good option would be to build yourself a simple delta..
Actually I did build a small one in balsa, but it's not yet finished. I put a nice set of wheels on it, but no rudder to steer it during take off - a hesitant work in progress while I decide on a rudder or steering nose-wheel!
FlyBoy20 is offline Find More Posts by FlyBoy20
Reply With Quote
Old Dec 10, 2012, 07:50 AM
PowerTower
RWData's Avatar
United Kingdom, England, Bristol
Joined Aug 2009
981 Posts
Who want's wheels on a simple delta ! Just do a 'chuck-n-throttle' so you can get some cheap air-time with an elevon model. Then... when you're done, modify to 'prop-in-slot' maybe
RWData is offline Find More Posts by RWData
Reply With Quote
Old Dec 10, 2012, 11:34 AM
Registered User
FlyBoy20's Avatar
United Kingdom, Wales, Swansea
Joined Aug 2012
513 Posts
Quote:
Originally Posted by RWData View Post
Who want's wheels on a simple delta ! Just do a 'chuck-n-throttle' so you can get some cheap air-time with an elevon model. Then... when you're done, modify to 'prop-in-slot' maybe
Well, it did start out as a chuck design, but other considerations came to light i.e sand; a problem I've had before. The obvious solution was to raise the motor up clear of the ground. Besides a ground take off is something I really want to do, and with the angle of incidence, it should launch itself on it's big front wheel and the two trolley wheels on the back?

It' all just pure experimentation - for fun!
FlyBoy20 is offline Find More Posts by FlyBoy20
Reply With Quote
Old Dec 10, 2012, 01:02 PM
PowerTower
RWData's Avatar
United Kingdom, England, Bristol
Joined Aug 2009
981 Posts
Fun is what it's all about
I have a central underside brace front to back and a couple of skid's about 60mm from wing-tip each side. I probably won't go for wheels 'cause I don't have any hard surface (or short & flat grass) to take off from. 'Experimentation', the abbreviated form in RC is 'TLAR' or 'That Looks About Right', I'm a fan of TLAR, the model-maker's licence
RWData is offline Find More Posts by RWData
Reply With Quote
Old Dec 10, 2012, 04:41 PM
Redacted per NSA "suggestion"
dedStik's Avatar
United States, VA, Virginia Beach
Joined Feb 2012
5,413 Posts
Quote:
Originally Posted by fastfwd View Post
her is a nice way to know if prop is right
Sorry to whomever posted this way to remember. Credit is someone here on RCG other than myself.

A boat going in reverse cavitates. The backside of a plane propeller is concave, cavitate concave. That's how I remember it.
dedStik is online now Find More Posts by dedStik
RCG Plus Member
Latest blog entry: Confessions of a smoker...
Reply With Quote
Old Dec 10, 2012, 06:38 PM
Rocket Programmer
jasmine2501's Avatar
United States, AZ, Mesa
Joined Jul 2007
25,355 Posts
Quote:
Originally Posted by dedStik View Post
Sorry to whomever posted this way to remember. Credit is someone here on RCG other than myself.

A boat going in reverse cavitates. The backside of a plane propeller is concave, cavitate concave. That's how I remember it.
I remember it by remembering that I've never seen a over-cambered airfoil, but I've seen the under-cambered type

And I just buy props with numbers on them. With the little props it can be difficult to see the curve.
jasmine2501 is offline Find More Posts by jasmine2501
Reply With Quote
Old Dec 12, 2012, 11:14 AM
Registered User
FlyBoy20's Avatar
United Kingdom, Wales, Swansea
Joined Aug 2012
513 Posts
Quote:
Originally Posted by RWData View Post
Fly, I'm guessing you mean %Rates then %Expo. Try setting 50/75% rates and 50% expo on all. That way you soften the stick around centre and still get 50/75% on surfaces at full stick..
Took you're advice on the D/R and expo..

Quote:
Originally Posted by RWData View Post
.. do some bench testing....how much deflection are you getting at full stick ..
Did this and only got about 8mm movement each way on 100% D/R, but slightly more on the up-elevator than the down..?

Anyway, with prop definitely on the right way, I attempted another 2/3rds throttle launch yesterday. Result: another nose-dive and a broken motor shaft!

At least I have a spare 1200Kv motor from my damaged Decathalon which I can try with a prop-saver next time.
FlyBoy20 is offline Find More Posts by FlyBoy20
Reply With Quote
Old Dec 12, 2012, 03:29 PM
PowerTower
RWData's Avatar
United Kingdom, England, Bristol
Joined Aug 2009
981 Posts
Fly... If it's still in one piece (or at least not too many pieces then !), try a little up elevator, maybe only 1-2mm on centred-stick. It probably could do with a bit to stay level and more stable. I have contacted a FB who has one of these and may have an idea what's going on, hopefully he will see the answer and get you up and running/flying
RWData is offline Find More Posts by RWData
Reply With Quote
Old Dec 12, 2012, 03:46 PM
Rocket Programmer
jasmine2501's Avatar
United States, AZ, Mesa
Joined Jul 2007
25,355 Posts
Almost sounds like a CG problem. If you toss it power off, can you glide it to a nice landing?
jasmine2501 is offline Find More Posts by jasmine2501
Reply With Quote
Old Dec 12, 2012, 04:56 PM
Reap the wild wind
headlessagain's Avatar
Bristol,UK
Joined Feb 2007
3,920 Posts
Fly
if you have the chance, try to re-maiden into the wind over a slope (at the beach?) If she drops a little you will have more height to catch it before it lawn darts. If you are solo launching then either power off launch and then gently apply power once clear of your hand or try a side arm launch at 70% power.
It might be best to try to source a replacement motor shaft than try the spare 1200Kv motor from your damaged Decathalon. Pusher jets need high kv motors unless running on a 6S pack! If you do decide on a different motor then I'd head over to the Radjet thread for some ideas http://www.rcgroups.com/forums/showt...1526264&pp=100
Andy
headlessagain is online now Find More Posts by headlessagain
Reply With Quote
Old Dec 12, 2012, 05:58 PM
Registered User
FlyBoy20's Avatar
United Kingdom, Wales, Swansea
Joined Aug 2012
513 Posts
Quote:
Originally Posted by jasmine2501 View Post
Almost sounds like a CG problem. If you toss it power off, can you glide it to a nice landing?
It's really gratifying to find so many helpful suggestions from the membership, amazing friendliness...

After the last failed attempt I did wonder if CofG was my problem, but I don't have any long grass where I can risk a test glide, and I've learned not to go anywhere near sand.

I've read loads of threads on the Radjet, and opinion seems divided where the CofG should be. Some say 400mm, others less. What I detected straight away was that the HK-fitted velcro patch is way too far forward for my TGY 1300mAh lipos. I've now taken the step of cutting foam away so that it can lie further back. I guess I'll just have to experiment with it, but at least I have a motor I can use a prop-saver with. I'll just have to prop up, as it's a 1200Kv - and hope I don't cut my hand off!

I also have an AX-1806N, which is a 2500Kv. It packs heck of a punch with a small prop, but I can't use a prop saver on it with any of my props, unfortunately.
FlyBoy20 is offline Find More Posts by FlyBoy20
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Radjet vs SkyFun Jet. Which one to get to replace my abused radjet. Koo Pusher Prop Jet Models 5 Mar 15, 2013 05:15 AM
Video Maiden Flight of the Noob 3 Wingman26 Electric Plane Talk 0 Aug 21, 2012 10:43 PM
Discussion Maiden with my Radjet 800! Koo Crash Discussion 16 Aug 15, 2012 08:02 PM