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jrevens
 Post subject: Thorp Flight Test Video
PostPosted: Mon Jan 27, 2020 3:57 pm 
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I thought this was very interesting. Lu Sunderland's old airplane...

https://www.youtube.com/watch?v=pbznX_69t6w

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fytrplt
PostPosted: Mon Jan 27, 2020 4:32 pm 
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What say Ye, Spanky?

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fulcrumflyer
PostPosted: Mon Jan 27, 2020 8:20 pm 
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Moi?
Somewhat interesting. However, the guy's a flight test engineer who fancies himself a test pilot, so I'd take what he says with a slight grain of salt. He has done some stupid stuff test flying a Stewart S-51 at KVIS. Cubes and I had the opportunity to see the S-51. It was a work of art. Then Seguin tried to trash it on the first flight. He said he was going to hammerhead out of a failed loop. Stall plus yaw equals spin. Luckily, the aircraft snapped off before he could get too much rudder in. It looked like the Thorp was very predictable and benign when it fell off in the failed loop. I've never spun my Thorp and I don't plan on it. I also don't think the Thorp has enough rudder authority to do a very good hammerhead. The rudder is kind of small and there's not a whole lot of moment arm.
I hope he realizes he's not going to open the Thorp canopy inflight (in order to jump out) unless he's either Arnold Schwarzenegger in his prime or going very slow. It didn't look like he had any quick-release pins.

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speedbird1
PostPosted: Mon Jan 27, 2020 9:14 pm 
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I noticed that he didn't even try a spin which I found strange for a so called test series? Also no stall sequence where he could have made a spin attempt?? When he was about to do a tail slide the rudder was flapped from side to side for some reason?? Everything he did was quite benign but quite within the envelope already established.
I wondered about that canopy and his chances of getting out of it complete with a 'chute??
Speedbird 1.

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jrevens
PostPosted: Mon Jan 27, 2020 10:22 pm 
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I just thought it might be interesting to others also... the good, the bad, & the ugly. It was nice to see Lu's airplane looking so good (to me).

As far as spins go, Speedbird1... maybe he knew a little bit more about the Thorp and spins than may be obvious from this video, before he started this particular test series. Then again, maybe not.

Spanky - I thought the same thing about the chute... like, most everyone flying a Thorp knows that, or should know that, right? My friend Gail Ables who built the V-tail "Thorp" with the tapered wing wore a chute on his first test flight. I thought at that time it was probably useless, and he admitted it probably was too. I didn't use one on my first test flights. Seguin did say he got flack from the peanut gallery for not wearing one during previous test flights, so maybe it was just for show in his mind, which is stupid. Or maybe not.

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speedbird1
PostPosted: Tue Jan 28, 2020 9:39 am 
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Yes, John, he did not mention a spin sequence so he is probably aware of bad habits. But there again there were no test cards with a sequence starting with climb, straight and level, turns, inset of stall etc, but that may well have been covered in a previous video?
The parachute did indeed seem to be in response to previous comments.
Being a fairly experienced nuwbie I have seen nothing much re the stall/spin habits of a Thorp?? Is that land, or air, not to be ventured upon??
Back to the video and that was a beautiful airplane without the BS Pledge polish.
Speedbird1

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fytrplt
PostPosted: Tue Jan 28, 2020 11:43 am 
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I have empirical evidence that the T-18 is not good at hammerhead turns. As Spanky pointed out, not enough rudder. Stalls are widely dependent on how true the as-built airfoil is to the plans. My plane with T-18 wings on it stalled fairly sharply and tended to roll to the left. With the S-18 wings on it, the stall is benign. Both variants gave plenty, if subtle, warning prior to departure. Recovery is swift, but you can easily induce a secondary stall if you rush the back stick. My spin experience is limited to a fairly light O-290 powered T-18. I found that normal recovery procedures worked just fine.

A word about full stall landings; the T/S-18 stalls at fairly high deck angle. The tailwheel is about a foot below the mains in the stall attitude. A full stall landing will result in the tailwheel touching first leading to a bounce when the mains come down. Your results may vary.

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fulcrumflyer
PostPosted: Tue Jan 28, 2020 2:56 pm 
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If you read the video comments, Seguin states he didn't do spins because they were outside the scope of the test program and that the Thorp's spin characteristics were already well known. Kind of like the well-known characteristics he re-explored. I think the next time I fly my Thorp I'm going to wear my Russian flight helmet from my MiG-29 days. I bet that'll look cool (like the flight helmet in this video).

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Andy475
PostPosted: Tue Jan 28, 2020 10:40 pm 
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Reading through Walt Griffan's notes he spun 78WG (mentioned it was a non-event if you ignore the altitude loss), and the bailout procedure is to use the canopy breaker. Interesting guide for things I will not be attempting. That is what the work plane is for.

-Andy


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Hagle347
PostPosted: Thu Jan 30, 2020 9:10 am 
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After viewing the video, I commented on his facebook post that I thought it odd that the right seat shoulder straps were floating free. I had always been taught to secure such items prior to flight. His response to someone else was that he didn't 'expect' to be upside down or negative. Hmm, Didn't pass the smell test for someone who tries to pass himself off as a 'test pilot'. On another note, right after that guess who was lurking my Old Farts Fly page and requesting a 'friend'. Yeah, I don't think so. I am however glad he didn't damage Lou's airplane.

Terry


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Fraser MacPhee
PostPosted: Thu Jan 30, 2020 3:30 pm 
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In the first year of owning my first Thorp, with sub 200 flight hours logged, I made the same mistake(that Terry pointed out) as did the pilot in the video.

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