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Thorpe F-20 build

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Old 09-11-2012, 03:17 AM
  #326
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Default RE: Thorpe F-20 build

Terry,
The video did not work out, I will have to read the book about the camera.....bummer. I would call Ron Ballard or put a post in the turbine section, Ron usually responds very quickly to questions. The stumper is that it ran so well the first flight attempt.
Glenn
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Old 09-11-2012, 04:41 AM
  #327
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Default RE: Thorpe F-20 build

Is this a gass start 44?
If so, check you do not have your gass and fuel lines reversed.
I have seen it before.

Paul G
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Old 09-11-2012, 08:48 AM
  #328
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Default RE: Thorpe F-20 build

Paul- it is a kero start but the lines are not backwards. No changes were made after the first run of the day and it went well.

Glenn- If you read the book will the video work? I am sure Ron Ballard will respond quickly with- "Ship it to me". That's what usually happens. His turn around time is quick. I just hate paying the shipping costs.

Ron Sweeny- I'll try your idea of jumping the pump with a battery. Seems like it is the problem at the moment. I'll check the solenoids again too.

Bob- Aren't you the local Wren Rep? Just kidding. I am sure Ron can help me. He alsways does. Just trying to figure things out on my own first. Usually these problems are self inflicted.

Terry
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Old 09-11-2012, 09:03 AM
  #329
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Default RE: Thorpe F-20 build


Quote:
ORIGINAL:

Bob- Aren't you the local Wren Rep? Just kidding. I am sure Ron can help me. He alsways does. Just trying to figure things out on my own first. Usually these problems are self inflicted.

Terry
I swear you told me the motor ran great on the stand?
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Old 09-11-2012, 11:45 AM
  #330
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Default RE: Thorpe F-20 build

And so it did! Three runs on the stand and all perfect. One run in the plane that was perfect. Then the problem occurred ending my day at the field.
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Old 09-16-2012, 05:22 PM
  #331
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Default RE: Thorpe F-20 build

Ron Ballard helped me get the Wren 44 going again by changing a few settings. Thank you Ron!

Today was the maiden for my Thorpe F-20 Tigershark. And what a perfect day for it. Sunny, about 78 degrees, light winds pretty much right down the runway, not a cloud in the sky. I raised the nose gear strut about 3/8" to give more angle of attack for take-off from the previous attempt. Went down the runway at about 35-40 mph and lifted off at about 300 ft or so. Then it rolled to the left as it was out of trim. Got it to about 150-200 ft and slowed it down to about half throttle and started working on the trims. Had to give quit a bit of up trim and right aileron. I noticed pretty quickly that the ailerons had a dead spot around neutral which caused me some difficulty. I think this is due to the slop in the cables. It would tuck in the turns if you went to slow and weren't quick on the aileron return. Had to really stay on the ailerons. Elevator was fine. Flew around at half throttle and about 90-100 mph. Set up to land and that is when it got interesting. The dead spot got worse as the plane slowed. It swayed back and forth until touchdown. It slowed down more than I expected to about 30 mph and sort of dropped down the last few feet to the runway then bounced back in the air and came back down more gently. This plane needs more elevator! Second flight was better but I ran out of elevator on the landing again and bent one the the main struts. Third flight was better still and I did a few rolls. Very axial and straight without any tendency to barrel. I landed at a higher speed around 35-40 mph which helped. But still it swayed back and forth on the airlerons. Flight time from take off to touchdown was about 5 minutes for each flight. Fuel remaining at the end of each flight was about 16-20 ounces. Not bad. I think I will begin increasing flight time by another 30 seconds or so and see how it goes.

After flying today I am convinced that these cables have got to go! I just have to figure out how to make that happen. Overall I am pretty happy. The plane looked good in the air and flew with authority. I did not try any high speed passes as I didn't feel comfortable with the ailerons around neutral. And it didn't seem like I had enough elevator throw. So I will work on that.

Thanks to all those who provided helpful comments and advice and especially to the Thorpe Brothers for their design. If I ever get someone to take a video of me flying it, I will come back and post it. Good luck to others who build this plane. Of course, if anyone has any questions....

Terry Jacobs
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Old 09-16-2012, 06:32 PM
  #332
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Default RE: Thorpe F-20 build

Good job

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Old 09-16-2012, 10:13 PM
  #333
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Default RE: Thorpe F-20 build

Glad you had success Terry.

This has been a very interesting thread to follow. I really like this style of modelling. It is a rare thing you have created in a world of ARFs

Thanks very much for taking the time to put it up for us.

Roger
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Old 09-16-2012, 11:43 PM
  #334
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Default RE: Thorpe F-20 build

Terry well done, a relief no doubt. Re elelvator response, have you checked your c of g? Re wren settings what did you alter,? Ron.
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Old 09-17-2012, 02:52 AM
  #335
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Default RE: Thorpe F-20 build

Glad you got it flying after all your hard work.

Only suggestion I could think of for the ailerons servos is to use two Hitec 5125 thin wing type servos, not going to be easy now to run cables.
You could also try to support the inner cable more as it comes out of the wing & at the servo, or what about just changing the inners to like what are used on the sullivan cables rather than the bowden cable you are using.
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Old 09-17-2012, 04:06 AM
  #336
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Default RE: Thorpe F-20 build

Congratulations Terry, I've enjoyed your build a lot.

Hope you get it sorted soon. - John.
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Old 09-17-2012, 07:29 AM
  #337
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Default RE: Thorpe F-20 build

Terry congrats on the maiden. It is nice to see someone actually build and have success with their project. I'm sure you'll sort out the issues quickly and have it flying on rails! I should have payed attention to Mikes text saying the field was virtually abandoned yesterday.
Bob
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Old 09-17-2012, 06:01 PM
  #338
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Default RE: Thorpe F-20 build

Thanks for all the kind words. Here are a few more pics of the plane that might be helpful to other builders. CG was spot on where the plans call for it to be, 11.75" forward of the inboard trailing edge.
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Old 09-17-2012, 06:04 PM
  #339
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Default RE: Thorpe F-20 build

A few more...
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Old 09-17-2012, 06:10 PM
  #340
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Default RE: Thorpe F-20 build

Ron- Here are a few pics showing the ECU settings that were changed. I increased each by 5 and the engine started and ran good. Shut it down, let it cool, then tried to restart. Got 6-8" of flame out the tail pipe on transition so I shut it down. Put the settings back to where they were and tried again. The engine started just fine. Shut it down and restarted again adn it worked well. Maybe something was stuck and came loose. Except for doing some popping on start-up, the engine is running fine now. Took it to the field and did the maiden without any further problems.

Bob- you missed a great day at Joyce for sure. But there is always next weekend...
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Old 09-17-2012, 10:54 PM
  #341
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Default RE: Thorpe F-20 build

Hi Terry, it looks as though you gave the pump a bit of a kick start, been there, done that, thanks, Ron.
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Old 09-18-2012, 02:30 AM
  #342
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Default RE: Thorpe F-20 build

Terry i noticed that your rx is very close to the ecu. It would be good if you can seperate them a bit more.
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Old 09-18-2012, 05:36 AM
  #343
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Default RE: Thorpe F-20 build

Bob- I agree. How much space do you think I need? I tried stuffing the RX further down with the battery but it was too tight.
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Old 09-18-2012, 07:22 AM
  #344
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Default RE: Thorpe F-20 build

2-4" minimum if you have the space
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Old 10-01-2012, 08:44 AM
  #345
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Default RE: Thorpe F-20 build

I now have 10 flights on the Thorpe F-20. Each flight I get more comfortable with it. I have done a few high speed passes at about 3/4 throttle and it appears to be going about 150 mph. Vertical performance is very good. At full throttle it goes straight up for about 1000 ft or so. I haven't tried to go higher as the plane gets small quick. It's still sensitive on the ailerons but I am getting use to it. Slows down pretty good for landing even though I do not have flaps. I comes in at about 1/4 to 1/2 throttle and nose high about two inches. Just enough to see the yellow on the bottom of the wings. If I don't see yellow, it is coming in too fast. Flight times are now 5-6 minutes with at least 10 ounces to spare. I'm really enjoying the plane. Everyone is surprised when they see that it is made of wood.

Terry
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Old 10-01-2012, 08:46 AM
  #346
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Made of wood?? What is that! LOL
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Old 10-01-2012, 10:43 AM
  #347
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Default RE: Thorpe F-20 build

Hi Terry, well done. I remember struggling with my JMP Phantom on landing approach and a full size Phantom pilot advised me that in real life if you could see the runway on finals then you were going to crash!! Keep you chin and your nose up. How about some video? Ron.
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Old 10-01-2012, 11:41 AM
  #348
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Default RE: Thorpe F-20 build

Ron- No one has shown up with a video camera as yet! As soon as I can talk someone into doing a video, I will post it. I'm sure you would like to see it fly. It looks similar to your videos at high speed but has beter take-off and vertical. Of course I try to land on the runway.

Terry
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Old 10-04-2012, 12:35 PM
  #349
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Default RE: Thorpe F-20 build

Well done.
Nice job.
I would get rid of the cables too!

Paul G
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Old 10-04-2012, 05:22 PM
  #350
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Default RE: Thorpe F-20 build

It will be a winter project for me. Already bought the servos and wire. Plan to fly it for now while the weather is still good.

Terry
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