Have Pink

Are you saying it has too little drag ?

That's 3"?!??!?


This is a much larger glider than I imagined...

iter said:

Are you saying it has too little drag ?

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No, I wasn't referring to drag, just looks.

CarVac said:

That's 3"?!??!?


This is a much larger glider than I imagined...

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2". 3' is the length (well 34" technically). The glider is still huge. 7' long.

Ari.

iter said:

2". 3' is the length (well 34" technically). The glider is still huge. 7' long.

Ari.

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Ah. I missed the single quote. Now it's more in line with my size expectations.

I had some unhappiness recently with motors blowing their fronts into electronics compartments in my gliders, and on gliders where that hasn't happened, it's been a constant concern.

I'm adding a bulkhead to Have Pink to prevent hot gasses from reaching radio components. This is a length of coupler, a plywood bulkhead and a stiffy that holds the bullhead in place. My hope is that if I have another motor failure, it ejects what remains of the motor and keeps the rest of the glider fliable.

Ari.

All together for the first time. Total length 84".

Ari.

Looks great!!

What motors are you planning to use for this? I don't think the H45 you originally mentioned is out yet....

Once you see that much 'stuff' in the sky, you'll have a hard time flying 3FNC stuff!

Thank you Mike. Gary announced last night that a few of the new DMSs passed certification, including H45 and I65. Have Pink is really more of an I or J glider than H. I do want a slightly faster-burning motor for my test flight, maybe I115 or DMS I140 with adapter. I worry about thermal protection for the trailing edge, and long-burns may be a bigger challenge in the regard.

H45 would be an excellent fit for Vulcan.

Ari.

This looks really fun! I'm looking forward to seeing video of the flight.

Makes me want to get off my duff and get my first RCRG finished.

Here it is in all it's complete, pink glory. It has a sort of heat shield on top surface now: corrugated cardboard with aluminum tape on top.

The thing is humongous. It's 7 feet long and over 7 lbs with the motor. Suddenly, the H100 I have in it seems small.

Ari.

It looks like fun Ari. Are you flying it on Saturday?

G-d willing

Looks awesome completed, Ari!!

Now, you've stated it weighs like 7lbs now. What motors you intending to fly this on? You mentioned I and J earlier. With the weight you have, I do not think a J90 will do, unless you are '45ing' it on the way up. The DMS I140 should be nice, pretty hot but not toooooo hot. BTW, I am planning to fly a new delta glider on that same motor this Saturday if I can, along with three other gliders using H/I motors.

While the elevons on this look nice, I wonder if they are sorta largish, and could potentially have a flutter issue at enough speed. The I140 should be a good go, or you could do a 'crawler' flight first, perhaps a larger H with just enough avg thrust to get this going but not enough I-t to get fluttering. Also, I'm wondering if you might, just might have a small pitch down inherency with the motor being up on the pylon there. The dihedral may/should be enough to negate this, but still, there's a heap o' drag below the thrustline. Hence, my suggestion to do a crawler boost first, where you can see/correct any off axis wanderings.

You know?

It reminds me a lot of the XB-70 Valkrie in planform. Not the dihedral, though.

Youse guys are going ta take videos right....I said right! :dark: :grin: :drool:


Richard :headbang:

So I have an H100 in it now. It's going to crawl alright on that motor. "Over 7 lbs" is with motor and adapter, empty mass is 6.2 lbs. Vulcan is 5.5 lbs and has flown on a lot of G54/H54s, and really gets going on an I49. The fastest motor Vulcan has flown on is H112.

So on one hand, my experience tells me that H100 is a nice, drama-free motor to use for first flight. On the other hand, the numbers make it look marginal. On the third hand, numbers on Vulcan look even more marginal yet I have 19 trouble-free boosts on it.

Maybe I'm just fidgety ahead of the test-flight.

I had though of I140 but now I'm reluctant to use a DMS motor on Have Pink. It is impossible to inhibit the smoke grain on DMS motors, and I worry about smoke grain cooking the tail for 14 seconds after motor burnout. It works fine for Vulcan where motor in in the back, but may be a problem with motor above wing and elevons.

Speaking of elevons, their size is the same as on the 1/2 version, and that one has no over-control tendencies.

Ari.

Have Pink stayed on the ground the whole weekend. I decided the wind was too strong for a first flight.

It did draw a lot of interest from the crowd.

In the photo: Leah is all ready for the night launch with an LED wig. We did have a couple of nice night launches and my 3" sewer-pipe rocket flew nicely on J180 this morning.

Ari.

Is the smoke grain really a heat issue for anything not touching the motor case? The glider should have enough forward airspeed to thoroughly mix and instantly cool the smoke output.

Maybe it's a smaller problem than I think it is. I like to stack chances unfairly in my favor Especially on first flights. If I cook the wing without a smoke grain, I know it's the motor. If I have a smoke grain and I cook the wing, I'll never know.

Also, Dave Schaffer had a heat damage on his 1/4 scale X-2 at BALLS which he attributes to heat from smoke grain. I have a lot of respect for Dave and his analysis.

Ari.

CarVac said:

Is the smoke grain really a heat issue for anything not touching the motor case? The glider should have enough forward airspeed to thoroughly mix and instantly cool the smoke output.

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Photos of Dave's X-2 with smoke damage: https://www.rcgroups.com/forums/showthread.php?t=1607888&page=14#post28382359

Ari.

iter said:

Photos of Dave's X-2 with smoke damage: https://www.rcgroups.com/forums/showthread.php?t=1607888&page=14#post28382359

Ari.

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That looks like a 75mm motor? The big diameter motors almost always have faaaaaaar longer tracking smoke durations and intensities than a 38mm.

Plus, that craft had a flat back area which would trap the hot gases; the only part on Have Pink which would possibly get roasted would be the support for the motor mount. Actually yes, you should protect that, rather than the top surface of the wings. (although they do deserve protection from the flame itself)

I believe Dave's X-2 uses a 54mm motor.

Ari.

Dave's X2 has a Kamm Effect tail which creates a low pressure area that the smoke grain flame will get trapped in and is likely the cause of the burning. I've seen substantial flame from some smoke grains, even without open flame the hot gasses must do some damage. That should be restricted to the base of Have Pink's motor. I have a D/E powered foam delta that has suffered melt damage 16" back of a 2" high motor mount but thats from the motor burn itself. To that effect I do have some trepidation for Have Pink's unprotected inboard elevons, only flying will tell.


Richard

Have Pink flew and crashed two weeks ago at MudRoc. I've been going through the wreckage and the videos trying to reconstruct the failure. My current theory is that high aerodynamic loads tore servos out of their mounts. The servos didn't strip, pushrods didn't break, but the servos are displaced. This is consistent with control problems and eventual loss of control on the glide.

I was able to correct for roll on the boost. I had some difficulty establishing glide (announcer pulls "he's just showing off" out of nowhere. I never perform aerobatics on maiden flights). For a couple of seconds I seem to have control, then the glider pitches down and I'm unable to recover from that dive.

The damage is surprisingly light considering the crash. I'm reluctant to repair it until I can confirm my theory of the failure and have some confidence that I can address it.


Ari.

[video=youtube;Mhwto4ImAeE]https://www.youtube.com/watch?v=Mhwto4ImAeE[/video]

Darn sorry about this, Ari!!!

Was wondering if you had the chance to fly this, I've had to sit out the last few months because of no waiver. What motor did you use here? I wonder if maybe the elevons had a tad of flutter (maybe not even noticable) and that stressed/displaced your servos? What if you made the next flight with a 'low-n-slow' motor just to confirm the overall controllability of the craft? We do know it boosts well, that's a plus there.

Glad the damage is light. That's why I tend to build in 'just enough' body tubing ahead of the main wing, so when a 'dorkage' like this occurs, there's just an easy BT repair instead of dealing with another wing.

Also built a 30" diameter 'Invader type' glider, using my old Novus Aero technique of boost ballasting/glide CG shifting deal. Should be good on higher G's and low/mid H's once I get the thing trimmed....that's the HARD part to do free flight!

:sad: !

I do hope you reinforce the servo mounts and fly again.


Richard

Ari, I would also think flutter would cause the servos to pull out, I made it full screen and 480p and quarter speed and it looks like you might be getting a bit of pitch oscillation right about 7 seconds just before or after burnout....that might be what did it.

Frank

There is a roll excursion on the boost which I'm able to control. After burnout I remember having some difficulty transitioning to glide, it seemed uncontrollable in roll--which the announcer revers to "barrel rolls." Then I got roll under control and though I might have it, but then I could not control pitch. This is consistent with one servo letting go--then you can either control pitch or roll with one elevon, but not both. It's possible that at that speed, servos would tear out with or without flutter. Of course, once a servo lets go, that elevon is going to flutter no matter what.

I have metal-gear full-size servos in it, and metal pushrods and giant-scale control horns... Balsa servo mounts turned out to be the weakest link.

Ari.