Tonight; My First Crash.

[Chris Anthony]

OK, I see how this is panning out. Off the bat, I would prefer it if "the stage in my RC career" was not brought into the technical side of any discussion. I can accept that it will be used against me when giving my account of flying situations and descriptions of what I think happened in the air, and what I say is likely to be treated as "racing driver's excuses". I guess this can't be avoided. But don't be afraid to explain technical details to me if you think what I have said is wrong, I am more than capable of understanding them. I am not trying to big up my experience, but I do not like getting fobbed off with "you're too inexperienced you won't understand" either. Just because I am new to the hobby, and haven't held TX sticks in my hands for as long as some, it doesn't mean I won't understand the engineering principles.

John Muir, good observation (did you ever write a book called "How to keep your Volkswagen alive"?). Perhaps the engine did cut out first. I'll be honest I can't remember. And to be more honest, now I have pretty much given up hope on establishing what actually went wrong. Whilst all these suggestions are good, my memory isn't becoming any clearer and unfortunately I don't recall enough about what happened to be able to point my finger at any of the suggestions with confidence and assign it as the probable cause.

BEB you said "Chris you say you had a small amount of elevator in - in the OP you quantify it as about 25% - that's not a small amount of elevator!". Firstly, I meant 25% at the TX stick, though I did not make this clear. But if this is how you had understood it BEB, you'd also realise that your comment is a little presumptuous, considering you do not know what TX rates I was using. Let me be clear, this is not the first time I have flown this trainer around inverted. I have done circuits inverted before, at much higher altitudes, and at throttle positions/speeds of around what I was using when I crashed. With this plane I was able to use near to 100% "down-elevator" at the stick and push over from inverted back to level flight. So assuming my air speed was around the same, and everything else was constant, how can 25% elevator cause a stall?

Peter, first of all, you are talking about stall speeds and how they vary under different conditions, yet you also say that stalling only occurs when a critical angle of attack is exceeded. If the latter is true, can you explain how a "stall speed" can even exist? This is the very idea that BEB was trying to dis-spell, and yet you have also said that BEB is right?

And Peter again, you do not seem to have grasped the point I was trying to make in the quoted section. So read the following paragraph and tell me which part is incorrect. First picture this. I can fly my trainer at full speed and hike on 100% up elevator. It doesn't stall. This must be because at full speed, with full elevator, the wings are not presented at an angle of attack past their critical angle. As I was trying to explain before, this must be down to aircraft design. More specifically, the design of the horizontal stabiliser, the elevator control surface sizes, and other general characteristics (I have presumed). But, it all comes down to the fact that the critical angle of attack is not exceeded. Now picture this. I am flying my aircraft at near engine idle speed, say 1/4 full speed. I then hike on 100% elevator, and the wing stalls. This must have occurred because the wing was taken past it's critical angle of attack. Now we agree that the critical AoA in both cases is common. So why then does 100% elevator at full speed not cause the wing to go past it's angle of attack? I am saying it is due to the interaction between hori-stab and elevator control surfaces at varying speeds. This essentially means that there is correlation between maximum AoA achievable and speed. And we know that there is correlation between AoA and stalling. Hence, there is correlation between stalling, and speed. And I feel that essentially the reason that you cannot cause a high-wing trainer, at least my trainer to high-speed stall is because of the aforementioned tail-plane design details. And this is why I am sure that it was not a stall that initiated my loss of control. So, again, please tell me which of my assumptions above is incorrect.

Sorry for the change of tone in this post, but it reflects the way I feel.

Chris

[Biggles' Elder Brother - Moderator]

Posted by Rob Jones 2 on 29/04/2014 19:21:30:

It is possible that if you were using Futaba rather than Teranis, you would be able to rule radio problems out completely.

I'm afraid the logic of that escapes me completely! Taranis receiver actually transmits received signal strength back to the Tx, there are preset alarms at two set points the first giving an early warning of low signal strength, the second giving a signal strength critical alarm. Having been a Futaba user for many years I'm not aware of this facility on their equipment?

BEB

[Biggles' Elder Brother - Moderator]

Oh dear Chris - clearly both Peter and I are far too presumptuous - I suppose that us told!

You said 25% elevator unless you have a truly crazy amount of expo in - that's still not a "small amount of elevator".

I would suggest a little less flexing of your "engineering credentials" (which on the basis of your comments above don't always appear to be as strong as you might think, at least in this area - and before you ask, yes I am qualified to make that judgement - very qualified in fact )

A bit less bristling might win you more useful advice - listening is an art you acquire by practice! There are a lot a very experienced people here offering you some advice - many have many years of flying knowledge, often full size as well as model - sometimes you appear very dismissive of them. Which is pity, because all that's going to lead to is them stopping advising you.

BEB

[Phil Green]

Lets look at it another way. Every time you fly your model you're risking your investment - sometimes model planes crash, its as simple as that. This was your first of many! My lads race bikes. Yesterday at Cadwell my youngest completely trashed his bike, the front went coming out of the gooseneck. He's an experienced racer. Its unfortunate, its upsetting, its expensive, its damned inconvenient a month before the TT - but its part of the hobby, and if a crash upsets you too much, then its your decision whether the pain outweighs the pleasure, and whether, like my youngest, you accept it and carry on!

Cheers

Phil

Edited By Phil Green on 30/04/2014 00:07:18

[Chris Anthony]

Please don't try and be-little me BEB. I have expressed nothing but an eagerness to listen. I have asked to be corrected in my assumptions. Would you care to do this? As it still hasn't actually been done. If you don't want to or can't then that's fine but don't try and turn it into a failure on my account.

"which on the basis of your comments above don't always appear to be as strong as you might think" Correct me if you think I am wrong! I don't even know what you are referring to here!

I am not trying to "flex" any engineering credentials, actually you just did this yourself. I have said that I will understand if something is explained to me clearly, so I am asking for people to do this. If I point out something that doesn't make sense to me, or if I point out what I believe to be failures in a theory or description, then I expect to be acknowledged and corrected. That's how a learning process works. I already know you are an engineer, which is why I thought you might be a little more receptive to this kind of testing and questioning.

"You said 25% elevator unless you have a truly crazy amount of expo in - that's still not a "small amount of elevator"." BEB, I actually said "a small amount of down-elevator (25%) on my TX stick", you seem to have interpreted this as 25% of throw at the control surface. Either you mis-read what I originally posted, or you made assumptions about my rates (what if I was using a 0.5 gain function on the TX?) Regardless of actual rates, as this was not the real point here, did you read what I said about the plane's ability to roll inverted with 100% of down-elevator? This I think puts things into perspective.

Phil, I appreciate your take on this. But "no reason for it to happen", with no disrespect to you or your boy, we both know this is just not true. Maybe you don't know what the reason was, but there was a reason. Would this be an acceptable statement on a super-bike team? No. The difference is of course how seriously each party decides to take things. You may think I am being too finicky trying to establish the cause, but I on the other hand don't want to send up another plane until I know what I did wrong the last time, so I can correct it, and think it would be silly to do otherwise. I know you understand this. I entered the hobby expecting crashes and loss, do not be mistaken. But I also expect to be able to understand why any accidents happen and to learn from them.

[Biggles' Elder Brother - Moderator]

Posted by Chris Anthony on 30/04/2014 00:37:49:

"You said 25% elevator unless you have a truly crazy amount of expo in - that's still not a "small amount of elevator"." BEB, I actually said "a small amount of down-elevator (25%) on my TX stick", you seem to have interpreted this as 25% of throw at the control surface. Either you mis-read what I originally posted, or you made assumptions about my rates (what if I was using a 0.5 gain function on the TX?) Regardless of actual rates, as this was not the real point here, did you read what I said about the plane's ability to roll inverted with 100% of down-elevator? This I think puts things into perspective.

I'm afraid that just indicates you don't understand what expo is then! And no, I'm not going to explain it - I suggest you use the search box - it doesn't answer back.

BEB

PS I bet Phil - like every one else on here - just loves you telling him how wrong he is about his son's mishap!

[Chris Anthony]

"I'm afraid that just indicates you don't understand what expo is then!". No it doesn't. I know what expo is and what it does, don't think that I need you to explain it. It's just another form of rate gain, but happens to be non-linear. Stop trying to hide the fact that you read my post wrong, or made incorrect assumptions and that you don't like to be corrected.

And that's fine, don't answer my questions. I'm sure you know it makes you seem as though that you cannot answer them. It's a shame, because you seem to know lots, and I've appreciated your advice in the past. Hopefully Peter will have a go without being so worried about protecting an ego.

And please don't try to stir a negative response from Phil against me. If he has one to give then he's free to do so, and doesn't need you coaxing one from him. I'm sure he realises that I meant no offence by the remark, and can see the point I was trying to make.

Edited By Chris Anthony on 30/04/2014 01:13:02

[Fatscoleymo]

I just lost interest.

You're on your own now as far as I'm concerned.

Talk about biting the hand.........

[David Ashby - Moderator]

....and with that I think we'll draw this one to a halt .

Thread moved to more appropriate section.

 

 

Edited By David Ashby - RCME on 30/04/2014 07:46:49