CARF-Models P-47 Thunderbolt
03-24-2015, 11:49 AM
#776
The torque from the big Moki generates the swing to the left on takeoff and this is best managed by moderating your throttle-up while of course putting in the requisite amount of right rudder. I use no more than 1/2 power on takeoff with the Thunderbolt, which makes the torque swing very manageable and presents a beautiful scale takeoff. I learned this a few years back on the CARF Corsair. I was doing every takeoff with full right rudder and the model still kept tracking all the way over to the left side of the runway before lift off. I happened to have been reading Alex Hendshaw's (Spitfire test pilot) book and he talked about how the Mk-XIV Spitfire with the 2,000 HP Griffon engine was impossible to take off at full power on pavement because he just could not generate enough counter-rudder (even with the larger fin/ruder) to overcome the torque of the Griffon. Aha! the Dull light came on in my brain and I learned to apply the 1/2 power takeoff rule to both of the big CARF warbirds. By-the-way, we tried a gyro on the Corsair and found it useless for our purposes. The throttle management technique was far more effective.
Another takeoff technique comes to us from the full scale tail dragger world. Hold a bit of elevator during the initial takeoff roll to keep the tail wheel in contact with the surface for steering authority until you allow the tail to rise up with sufficient airflow to ensure rudder authority. This technique is 50% of the solution to a straight, scale Thunderbolt takeoff. With that huge stab the Thunderbolt tail will come up right away with a blast of wind from the prop, the problem is the rudder does not have sufficient authority to counter the torque swing at that point. If I had to put numbers to it, I'd say hold the tail down for about 25 feet, then gently release the elevator input and allow the tail to come up.
A quick story to end the torque swing discussion. My friend, the Corsair owner, attempted his first takeoff with the Corsair and the model got squirrely during his initial power up. He reacted like most beginners do and hammered the throttle to full power. The Corsair swung 90 degrees to the left and he horsed it off the runway in a stalled condition. Luckily for him the Moki 250 was checking in with all cylinders and the surface dropped away in a slight depression. He flew it out of that situation and was shaking so bad I had to take the transmitter and complete the flight. To close...throttle management, throttle management, throttle management.
Another takeoff technique comes to us from the full scale tail dragger world. Hold a bit of elevator during the initial takeoff roll to keep the tail wheel in contact with the surface for steering authority until you allow the tail to rise up with sufficient airflow to ensure rudder authority. This technique is 50% of the solution to a straight, scale Thunderbolt takeoff. With that huge stab the Thunderbolt tail will come up right away with a blast of wind from the prop, the problem is the rudder does not have sufficient authority to counter the torque swing at that point. If I had to put numbers to it, I'd say hold the tail down for about 25 feet, then gently release the elevator input and allow the tail to come up.
A quick story to end the torque swing discussion. My friend, the Corsair owner, attempted his first takeoff with the Corsair and the model got squirrely during his initial power up. He reacted like most beginners do and hammered the throttle to full power. The Corsair swung 90 degrees to the left and he horsed it off the runway in a stalled condition. Luckily for him the Moki 250 was checking in with all cylinders and the surface dropped away in a slight depression. He flew it out of that situation and was shaking so bad I had to take the transmitter and complete the flight. To close...throttle management, throttle management, throttle management.
03-24-2015, 04:19 PM
#777
is anyone flying their thunderbolts with an iGyro? Or any other 3 axis gyro? Wondering if 3 axis stabilisation will really make a difference? What are the issues, if any, with this plane anyway? Besides the plane wanting to veer off to one side during take off. This can be addressed with the iGyro very well.
03-25-2015, 08:38 AM
#778
My Feedback: (13)
The torque from the big Moki generates the swing to the left on takeoff and this is best managed by moderating your throttle-up while of course putting in the requisite amount of right rudder. I use no more than 1/2 power on takeoff with the Thunderbolt, which makes the torque swing very manageable and presents a beautiful scale takeoff. I learned this a few years back on the CARF Corsair. I was doing every takeoff with full right rudder and the model still kept tracking all the way over to the left side of the runway before lift off. I happened to have been reading Alex Hendshaw's (Spitfire test pilot) book and he talked about how the Mk-XIV Spitfire with the 2,000 HP Griffon engine was impossible to take off at full power on pavement because he just could not generate enough counter-rudder (even with the larger fin/ruder) to overcome the torque of the Griffon. Aha! the Dull light came on in my brain and I learned to apply the 1/2 power takeoff rule to both of the big CARF warbirds. By-the-way, we tried a gyro on the Corsair and found it useless for our purposes. The throttle management technique was far more effective.
Another takeoff technique comes to us from the full scale tail dragger world. Hold a bit of elevator during the initial takeoff roll to keep the tail wheel in contact with the surface for steering authority until you allow the tail to rise up with sufficient airflow to ensure rudder authority. This technique is 50% of the solution to a straight, scale Thunderbolt takeoff. With that huge stab the Thunderbolt tail will come up right away with a blast of wind from the prop, the problem is the rudder does not have sufficient authority to counter the torque swing at that point. If I had to put numbers to it, I'd say hold the tail down for about 25 feet, then gently release the elevator input and allow the tail to come up.
A quick story to end the torque swing discussion. My friend, the Corsair owner, attempted his first takeoff with the Corsair and the model got squirrely during his initial power up. He reacted like most beginners do and hammered the throttle to full power. The Corsair swung 90 degrees to the left and he horsed it off the runway in a stalled condition. Luckily for him the Moki 250 was checking in with all cylinders and the surface dropped away in a slight depression. He flew it out of that situation and was shaking so bad I had to take the transmitter and complete the flight. To close...throttle management, throttle management, throttle management.
Another takeoff technique comes to us from the full scale tail dragger world. Hold a bit of elevator during the initial takeoff roll to keep the tail wheel in contact with the surface for steering authority until you allow the tail to rise up with sufficient airflow to ensure rudder authority. This technique is 50% of the solution to a straight, scale Thunderbolt takeoff. With that huge stab the Thunderbolt tail will come up right away with a blast of wind from the prop, the problem is the rudder does not have sufficient authority to counter the torque swing at that point. If I had to put numbers to it, I'd say hold the tail down for about 25 feet, then gently release the elevator input and allow the tail to come up.
A quick story to end the torque swing discussion. My friend, the Corsair owner, attempted his first takeoff with the Corsair and the model got squirrely during his initial power up. He reacted like most beginners do and hammered the throttle to full power. The Corsair swung 90 degrees to the left and he horsed it off the runway in a stalled condition. Luckily for him the Moki 250 was checking in with all cylinders and the surface dropped away in a slight depression. He flew it out of that situation and was shaking so bad I had to take the transmitter and complete the flight. To close...throttle management, throttle management, throttle management.
03-25-2015, 08:44 AM
#779
The torque from the big Moki generates the swing to the left on takeoff and this is best managed by moderating your throttle-up while of course putting in the requisite amount of right rudder. I use no more than 1/2 power on takeoff with the Thunderbolt, which makes the torque swing very manageable and presents a beautiful scale takeoff. I learned this a few years back on the CARF Corsair. I was doing every takeoff with full right rudder and the model still kept tracking all the way over to the left side of the runway before lift off. I happened to have been reading Alex Hendshaw's (Spitfire test pilot) book and he talked about how the Mk-XIV Spitfire with the 2,000 HP Griffon engine was impossible to take off at full power on pavement because he just could not generate enough counter-rudder (even with the larger fin/ruder) to overcome the torque of the Griffon. Aha! the Dull light came on in my brain and I learned to apply the 1/2 power takeoff rule to both of the big CARF warbirds. By-the-way, we tried a gyro on the Corsair and found it useless for our purposes. The throttle management technique was far more effective.
Another takeoff technique comes to us from the full scale tail dragger world. Hold a bit of elevator during the initial takeoff roll to keep the tail wheel in contact with the surface for steering authority until you allow the tail to rise up with sufficient airflow to ensure rudder authority. This technique is 50% of the solution to a straight, scale Thunderbolt takeoff. With that huge stab the Thunderbolt tail will come up right away with a blast of wind from the prop, the problem is the rudder does not have sufficient authority to counter the torque swing at that point. If I had to put numbers to it, I'd say hold the tail down for about 25 feet, then gently release the elevator input and allow the tail to come up.
A quick story to end the torque swing discussion. My friend, the Corsair owner, attempted his first takeoff with the Corsair and the model got squirrely during his initial power up. He reacted like most beginners do and hammered the throttle to full power. The Corsair swung 90 degrees to the left and he horsed it off the runway in a stalled condition. Luckily for him the Moki 250 was checking in with all cylinders and the surface dropped away in a slight depression. He flew it out of that situation and was shaking so bad I had to take the transmitter and complete the flight. To close...throttle management, throttle management, throttle management.
Another takeoff technique comes to us from the full scale tail dragger world. Hold a bit of elevator during the initial takeoff roll to keep the tail wheel in contact with the surface for steering authority until you allow the tail to rise up with sufficient airflow to ensure rudder authority. This technique is 50% of the solution to a straight, scale Thunderbolt takeoff. With that huge stab the Thunderbolt tail will come up right away with a blast of wind from the prop, the problem is the rudder does not have sufficient authority to counter the torque swing at that point. If I had to put numbers to it, I'd say hold the tail down for about 25 feet, then gently release the elevator input and allow the tail to come up.
A quick story to end the torque swing discussion. My friend, the Corsair owner, attempted his first takeoff with the Corsair and the model got squirrely during his initial power up. He reacted like most beginners do and hammered the throttle to full power. The Corsair swung 90 degrees to the left and he horsed it off the runway in a stalled condition. Luckily for him the Moki 250 was checking in with all cylinders and the surface dropped away in a slight depression. He flew it out of that situation and was shaking so bad I had to take the transmitter and complete the flight. To close...throttle management, throttle management, throttle management.
excellent post !! Having a lot of power comes with great responsibility !!!
Voy
03-29-2015, 07:40 AM
#780
Just wondering if its a good idea to test fly the Jug without the cowl for initial flights? New to radials, so just a bit wary. Moreover, I want to fly around with a 2 bladed SEP prop initially... And with the cowl installed, this option is not possible as the prop touches the cowl. With the carf hub and prop, the gap increases but I would rather not use a 4 bladed setup during initial flights? Not sure which is the right path to choose.
thanks in advance.
thanks in advance.
03-29-2015, 08:07 AM
#781
Ragz,
I would suggest that you do not fly it with out the cowl. I you have a baffle inside the cowl i would rather see that you have it on so that you get the most effective cooling for the engine. As far as using the 2 bladed prop i would look into getting a spacer to add behind the prop so that you can use it. I'm thinking a 1/4 inch should do the trick. I ordered one from Gotz Vogelsang hear in the U.S but i don't think i will use it. I have the 4 bladed prop on mine and i have had no problems with it.
I would suggest that you do not fly it with out the cowl. I you have a baffle inside the cowl i would rather see that you have it on so that you get the most effective cooling for the engine. As far as using the 2 bladed prop i would look into getting a spacer to add behind the prop so that you can use it. I'm thinking a 1/4 inch should do the trick. I ordered one from Gotz Vogelsang hear in the U.S but i don't think i will use it. I have the 4 bladed prop on mine and i have had no problems with it.
Last edited by Greg Wright; 03-29-2015 at 08:13 AM.
03-29-2015, 10:16 AM
#782
Ok Greg, I like the idea of the spacer. Perhaps using the prop washer as a spacer would be a good idea...Basically this would mean getting another prop washer and longer bolts...Yes I have baffled the engine by sticking the baffle to the cowl. I am concerned about air flow over the exhaust collector ring though...as per the 132 page moki thread, it tends to get red hot...
03-29-2015, 01:04 PM
#783
Ok Greg, I like the idea of the spacer. Perhaps using the prop washer as a spacer would be a good idea...Basically this would mean getting another prop washer and longer bolts...Yes I have baffled the engine by sticking the baffle to the cowl. I am concerned about air flow over the exhaust collector ring though...as per the 132 page moki thread, it tends to get red hot...
the collector ring.
Last edited by Greg Wright; 03-29-2015 at 01:08 PM.
03-30-2015, 05:27 AM
#784
Sharing a few images from this evening. I have decided to go with the SNAFU scheme. Its the most documented and available scheme on the net i think. And it looks very nice. Haven't started work on the canopy yet...I hate doing canopy work... The carf blade is 1100gms with the hub as compared to the SEP 32x18 which is only 360gms... dramatic weight difference. I wanted to do the initial flights with the SEP so i will need to add extra nose weight.
03-31-2015, 02:48 AM
#787
I am going to setup the carf blades tonight. I have a few questions. The 4 blades have come with a number painted on the root of the blade and another long number on the prop length wise. Please see pictures. I believe these are ref. numbers for the factory for ordering new blades. I am wondering if there is a pattern to place these in the hub? There are 3x 152 and 1x 151. The long numbers are in sequence ending with 5, 6, 7, 8. How does this work? The instructions are in german, but the pictures seem to ask you to measure out 35.50 cms for the P47 from the centre of the hub outwards to the tip of the prop and insert the wedge from the LE end of the prop. How much does the wedge need to go in? The more I insert the edge the greater the angle...This is not clear in the instructions. The wedge diagram given in the manual is also not to scale. Im so lost here.
I ran up the engine on the airframe today, and even with pump pressure to the minimum, the engine seems to run fine.. while the engine was running, I played around with the pump pressure but obviously there was no difference to the engine rpm...perhaps, I will need to play with pump pressure and lean out the needles to find the sweet spot... but this seems rather unreasonable...Any suggestions?
I ran up the engine on the airframe today, and even with pump pressure to the minimum, the engine seems to run fine.. while the engine was running, I played around with the pump pressure but obviously there was no difference to the engine rpm...perhaps, I will need to play with pump pressure and lean out the needles to find the sweet spot... but this seems rather unreasonable...Any suggestions?
03-31-2015, 04:19 AM
#788
OK, I figured this out. The 151 and 152 are weights in grams. Mine are +/- 0.5gms off these. Now I have used the jig at 35.50cms from the centre of the hub until both ends of the blade rests flat on the jig. Am I ok to go from here?
04-06-2015, 06:01 AM
#789
I am thinking of getting a detailed almost ready to install cockpit set from dynamic balsa. Wondering if someone has images from their thunderbolt with the dBalsa setup installed? I need to know how much work is needed to complete the install.
04-06-2015, 08:02 AM
#790
this is what i used on my cockpit
I made the backside of the panel with some styrene wires, servo wires and music wire.. I like the open look of some of the P47s with the hood removed or pulled back ..
Voy
04-06-2015, 08:21 AM
#791
Hi Voy,
I have written to iflytailies a few days ago. Awaiting a response. Nice to hear from you, I think yours is the most spectacular p47 i have ever seen. Where is it these days?
I have written to iflytailies a few days ago. Awaiting a response. Nice to hear from you, I think yours is the most spectacular p47 i have ever seen. Where is it these days?
04-06-2015, 09:34 AM
#792
Its currently in my basement RTF .. I just have not had any time to fly :\ I was about to sell it last year, and I am very glad i did not. I was panning to build an even more scale one, but i know i wont have time for a long time, and there are so many other projects i have piled up also ! as for Alex, he might be away as he travels around the holidays sometimes.
this is the direct manufacturer, but they would take at least 4 - 6 weeks . Beautiful products !
... Id say give Alex a few days to respond ....http://www.aerocockpit.com/en/7-esho...kpit-kits.html
Voy
04-28-2015, 03:15 AM
#793
I just received the cockpit kit and panels from iflytallies...great looking stuff.. Can someone share their setup so I can use that as a guide to build mine? This is my first scale cockpit. Do I need to start by building a box with the green panel sheets?
thanks in advance.
thanks in advance.
04-28-2015, 03:38 AM
#796
My Feedback: (43)
Ragz,
There are a lot of parts and it takes me about a week to finish it but I like the results. All parts are individually bagged and you get an excellent instruction manual plus a DVD with lots of pictures. Like anything, break a complex component down into parts/modules and it's a lot easier.
Everything in the pictures are from the kit.
There are a lot of parts and it takes me about a week to finish it but I like the results. All parts are individually bagged and you get an excellent instruction manual plus a DVD with lots of pictures. Like anything, break a complex component down into parts/modules and it's a lot easier.
Everything in the pictures are from the kit.
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06-08-2015, 10:51 AM
#797
MissBehave/Lil Lo Weathered
I finally finished the weathering on Mike's MissBehave. We took it to the SOCAL Scale Squadron Warbirds and Classics this past weekend and had a great time showing and flying it. Mike let me take it up against Brian Young and his FW-190.
Last edited by Growler84; 06-09-2015 at 11:21 AM. Reason: Add photo
08-14-2015, 06:49 AM
#799
Finally it flew. Here are the links to two videos.
Test flight
https://youtu.be/x8hVP--1E_g
Second flight
https://youtu.be/bP4QmnAbwMg
The videos are very basic, just very excited to share.
Test flight
https://youtu.be/x8hVP--1E_g
Second flight
https://youtu.be/bP4QmnAbwMg
The videos are very basic, just very excited to share.
