First major accident, would love some input.

[skywalker73]

Hello everyone, I recently purchased a t-rex450se v2. My goal is to use it for AP. I ordered an askman mount and should be recieving it this weekend. In the meantime I rigged up my old Kodak 4mp camera(7 oz.) on the t-rex with a modified mount that I had been using on my Blade CP-pro. I flew It a couple of times with no issues. On Tuesday I was at a park and decided to fly a little higher than before, The heli was very stable, but then all the sudden things changed. As I was descending, the heli started weaving around and then the tail kicked sideways. I almost gained control back, but ended up crashing. I was flying in normal mode and was wondering if my head speed dropped too low while trying to descend. I am using a DX-7, 401 gyro with a digital Futaba servo on the tail, stock 35amp esc, stock motor and 2100mah batt.
Should I be flying in an idle up mode to keep the headspeed up? What kind of headspeed should I be using and has anyone experienced anything like this before? I have noticed a lot of similar type crashes on youtube(loss of tail control),and usually the pilot is still using the training gear.
If anyone has a similar setup and is having good success, could you please share your setup(blades, pitch curves, headspeed ect.) with me. The camera I am planning on using is a Canon sd750 that weighs 5.3 oz.
For everyones enjoyment(and hopefully input) here is the onboard video of the crash! http://www.youtube.com/watch?v=SqjJf_DqQKk :arggg:

[EricTheRed]

Enjoyed the video, been there... Ok, my first thought was indeed your head speed dropped too low for the tail rotor to maintain a heading. Since I dont fly a TRex 450, and the smallest bird that I have is a Logo 10, my opinoin should be discounted. I do fly in Idle up to ensure that I dont drop my head speed during decents.
-Eric

[skywalker73]

Thanks Eric. The good news is the actual damage was not that bad(except for the camera), but at least I used an older camera. It shocked me how much less expensive the parts were for the t-rex compared to my cp.
Do you have any suggestions on set-up for an application like this?? I need all the help I can get.

[Tonystott]

Thanks Eric. The good news is the actual damage was not that bad(except for the camera), but at least I used an older camera. It shocked me how much less expensive the parts were for the t-rex compared to my cp.
Do you have any suggestions on set-up for an application like this?? I need all the help I can get.
IMO you shold always fly in idle-up to avoid this very issue. I would bet that you lost control due to lack of headspeed on descent.

[double0757]

To low headspeed, for the weight. Seen it on a friend. Try 12T and 100-90-100 on the idle up mode. Practice idle up flying. I land Idle up then immidiatley go throtle hold, before I go completly idle on the stick. I also fly 13T and 100-90-100 for 2800 rpm head speed, but that is for 3d. Hope it helps. Double O

[speed808]

Use the idle up next time. The very first time I hovered my T-Rex 450SE, I started to use the idle up right away. Lucky for me I did, I was hovering and decided to hover higher. As I got higher, the wind kicked up and started to lift and carry the heli away. Because I was in idle up, I was able to force the heli down with negative pitch and save it.

If I was in normal mode, my T-Rex would have crashed on its first flight. Learn to use idle up, the higher speed makes the heli more stable and if the wind kicks up, you can bring it down faster and save it from being blown away. There is one drawback, if you crash, the damage might be greater since your head speed is higher. But for me, I would rather be in idle mode and avoid a crash in the first place.

[Tonystott]

Along with idle-up, you want to also make sure you have throttle hold on an easy to reach switch, so if the flight goes pear-shaped, you can at least reduce the damage when it bites the dust

[skywalker73]

Thank You!!--It took me about a week to rebuild my bird.
I'm so glad everyone was willing to help me out. Give me a couple of weeks, and hopefully I will be able to share some nice shots!

[daniel reese]

Not to be a chump and all but I dont think you can blame this on mechanical or set-up problems. You can hear the motor winding down, and you can see there's a bit of a breeze...but neither of these is causing the major problem...IMHO.

I know it's just my two cents, but Ive watched my buddy do this MANY times...while decending, head speed did drop, which makes things a bit sloppier but not anything close to unfliable- even with a 7oz weight on it. But when the the heli was on its way down, it started o turn on you a bit...eventually it got pretty near to nose-in. It was THEN that you appeared to start to have REAL problems. You can hear the motor spinning up & winding down; can see the stick stirring going on...Im gonna hafta call this one operator error.

Your experience with the CP is only marginally applicable to a TRex. You need to be good at flying ALL attitudes/altitudes & from every perspective before you try putting anything expensive on the TRex. The 450 is capable of carrying quite a bit of weight, and carrying with considerable stability...even without idle-up (done it for years myself).

Yeah, its cruel, its harsh, but its my opinion (for what its worth). There's plenty of merit to learning to fly in idle up, but idle up or not, THAT's not the problem.

Guess I just felt compelled to chime in on behalf of all the non-3D guys who learn to safely, skillfully, and with great precision, fly their helicopters without idle up, without boundless expense on top-of-the-line "upgrades". Guess Im just trying to say that no improvement in equipment or tuning of electronics can serve in place of skill.

Please dont take insult over this. That's not my intent. Just venting my frustration at the countless "advice" givers who bury operator problems with equipment upgrades. Again, this aint directed at anyone in particular.

[aramsdell]

DX7? 3 pt curves huh? Must be a lot tougher. I've got my Rex on a Hitec with 5 pt curves. Thr. 0,100,100,100,100.
Pitch -4 deg linear to about +9. This allows me to descend under full power. I only fly in normal with mine because of this.

[Fall2Fast]

Skywalker, don't let that last guy get you down, its funny how he makes it seem setup is not that important yet he writes this long post for another person http://www.helifreak.com/showthread.php?t=45242

align's bec is set in gov mode on default and you may have been going in and out of gov mode due to below a 40 - 50% amount of throttle on decent, which will rev the motor like that and cause the spin as the rotor is spooling up very fast. Now after that I have to agree a good pilot could have saved it, but still having a good set up is important and let’s not skip step one.... setting up the helicopter properly for flight. :)

also I read some FAI pilots settings and they use a mix to roll right, a mix to roll left, another mix for loops and so on, the radio flys for them... NOT all of them mind you, but I don't know if they are better programmers or pilots... just my 2 cents.

I normally don't do this, but what the heck..... don’t like someone picking a person trying to learn

[bullaculla]

DX7? 3 pt curves huh? Must be a lot tougher. I've got my Rex on a Hitec with 5 pt curves. Thr. 0,100,100,100,100.

Actually, DX-7 has 5 point pitch/throttle curves, but in an idle up mode, you really only need 3.
You are pretty close to 100% straight across. Why dont you just go into idle up at 100% flat?

[skywalker73]

I am trying to program the idle up switch on the DX7, but the menu only goes up to 50%?? Am I missing something??

[skywalker73]

oops-never mind last post, I was fooling with the throttle hold switch

[skywalker73]

Hello, I gave the t-rex another try today using the set up advice everyone has shared. I programed stunt 1 mode with a steep throtle curve that winds up and stays at 85% throttle at less than 1/4 stick(I just felt comforable at that speed). I also gave the pitch curve a little negative at low stick, then a pretty much linear scale up to 100% positive pitch.
The heli flew great!! No more problems desending, and it flew so smooth with the higher head speed. I now am a firm believer that the proper set-up for this type of flying is critical.
I feel quite confident I never would have wrecked if I would have been flying with this set up. I do agree that I am still a noob, and a more experienced pilot may have been able to recover from that spin. Thanks everyone for your input!
Here is some footage from today http://www.youtube.com/watch?v=Bi6Dk0DpHkM