P-38 Lightning Brotherhood
#1327
Join Date: May 2006
Location: , IN
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Congratulations on the rebuild and maiden!! To answer your questions The wingspan is 126" and is the CBA P-38 original molds from Bob Antonell Sr. When I was living in Ohio and in my younger years I met Bob Sr at an IMAA event when I was with Miles Reed flying the local events. I fell in love with his P-38 which at that time he developed molds to expedite building the larger version of his P-38 model. I always kept in the back of my mind that I always wanted one of his models but of course wasn't able to at the time. I have since then gained a lot of experience with composite materials since I am into turbine jets and have made several molds of our own designs with great success. Kram I see you have a flying version with DA-50's and read that you have improved on the flap system. Would like to know of course any info on the flaps and what gear your using. Any of your input to make this model a better more improved version, I would appreciate. I will still need to acquire a vacuum forming system to make the canopies but I have the molds for them. For all inclusive purposes all the molds are in pristine condition and raring to go. Will need to put some engineering into the the interior supporting of the spar tube, gear plates, etc. But nothing that we cant handle with experience and time. Was considering electric gear due to reliability and simplicity that I have had with my jets.
#1329
My Feedback: (7)
70 ragtop: Yeah, although I've owned it for > 10 years, I am the last of several owners on this beast, and by the looks of it and the way it used to land, I'm sure the gear doors have been ripped off more than once. Now with the Fowlers and the CG moved up to 5.5", it's time to consider putting them back on. Of course, I will have to fabricate them and re-engineer the bays for attachment. Maybe cz-7a can help me with the fabrication
#1330
My Feedback: (7)
cz-7a: Very exciting to hear you have the molds and the skills to put them to use! I did not know they existed
This is a most impressive beast of a P-38 and very stable in the air. Everybody at at any flight field pretty much stops what they're doing to watch when you fire it up and point it into the wind.
Some of that may be due to they think I might put on a great calamity show
My "only" trouble with it over the years has been a disturbing tendency to land like a flying manhole cover, with a pancake stall speed of about 40 kts: doesn't tip to either side, just COMES DOWN when you get below about 40
That appears to have been solved by the flaps and the CG change. I had the long runway and a little headwind, but it appeared to really float on my first pass at 40 kts
The "weak spot" inherent to all 38's in the booms appears to be laid in with some carbon fiber, not sure if during manufacture or after-market
I thought the gear was made by a guy named Gene Barton in MO, but when I sent him some bent mains to repair several years ago, he denied they were his, although he did a really nice job of re-build. They are air-up and what I can only describe as "spring-assisted air-down." I also have an all-air back-up set by Robart, which is much "slicker"-looking, but much less heavy duty. I have never flown with the Robarts
My inboard Fowlers are air-driven, separate tank from the gear, while my outboards are the painstaking servo-driven self-built pieces of art it took me all winter to copy off JQ's CBA. I'll try to post some pics, if I can find them
Once I got the DA-50's rebuilt and found the perfect prop match (Xoar 20-12's) they turn 6900, and I think are the perfect propulsion for this model. After the batteries to the nose and adding 2 lbs of lead to get the CG JQ recommended, my filled-up weight is up to about 64# and I had to dial in about 15 clicks of up elevator during the maiden and did NOT require any down elevator mix during flap deployment, as have many of my other 38's
Very excited you have the molds. Keep us updated on your progress
This is a most impressive beast of a P-38 and very stable in the air. Everybody at at any flight field pretty much stops what they're doing to watch when you fire it up and point it into the wind.
Some of that may be due to they think I might put on a great calamity show
My "only" trouble with it over the years has been a disturbing tendency to land like a flying manhole cover, with a pancake stall speed of about 40 kts: doesn't tip to either side, just COMES DOWN when you get below about 40
That appears to have been solved by the flaps and the CG change. I had the long runway and a little headwind, but it appeared to really float on my first pass at 40 kts
The "weak spot" inherent to all 38's in the booms appears to be laid in with some carbon fiber, not sure if during manufacture or after-market
I thought the gear was made by a guy named Gene Barton in MO, but when I sent him some bent mains to repair several years ago, he denied they were his, although he did a really nice job of re-build. They are air-up and what I can only describe as "spring-assisted air-down." I also have an all-air back-up set by Robart, which is much "slicker"-looking, but much less heavy duty. I have never flown with the Robarts
My inboard Fowlers are air-driven, separate tank from the gear, while my outboards are the painstaking servo-driven self-built pieces of art it took me all winter to copy off JQ's CBA. I'll try to post some pics, if I can find them
Once I got the DA-50's rebuilt and found the perfect prop match (Xoar 20-12's) they turn 6900, and I think are the perfect propulsion for this model. After the batteries to the nose and adding 2 lbs of lead to get the CG JQ recommended, my filled-up weight is up to about 64# and I had to dial in about 15 clicks of up elevator during the maiden and did NOT require any down elevator mix during flap deployment, as have many of my other 38's
Very excited you have the molds. Keep us updated on your progress
#1335
Join Date: May 2006
Location: , IN
Posts: 37
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Cba p-38
Good information on the booms needing carbon reinforcement. Will incorporate that into the layups for the booms for sure. Where is your reinforcement placed on the booms exactly? Once I get back home I will take some images of the molds and post them for you. So as far as CG placement and speed on the flare, I usually also would be playing with the CG until I found a comfortable flare speed that didn't require throwing out an arresting hook to haul the model to a stop. I've notice with my jets that they like an aft CG when coming in to allow you maintain a positive attitude of attack and have control to flare and not tear the weak gear off on these very heavy models. It sure would be nice if I could come up with a flap system that would be more modern and trouble free and the plans I have also show the air version you have with the outboards being servo operated. Will look into this with a cad program.
#1336
My Feedback: (7)
Inside the booms, carbon fiber seems to run from about 4" in front of the gear bay door opening to about 6" aft
It's on the sides and about 5" wide and maybe? 6 oz cloth (hard to tell)
Starting from scratch, maybe you can build this plane a lot lighter than mine has become. VQ-38's (ARF's) had mass-produced Fowlers that worked on the same basic principle and worked really well, whereas mine required a ridiculous degree of tweaking and customization and TIME
I've always admired the way jet pilots mega-flare and seem to achieve both lift and air-braking
Maybe they're just better than I am at giving just the right amount of elevator at just the right time, but I've never been able to do that with a P-38. My approaches and touchdowns have always been shallow and fast and level and rate of descent almost purely controlled by throttle, except just enough flare to take the sting out of the last 6 inches. Just like you see in the pictures I posted.
I was surprised that moving the CG up > 1.5" resulted in a softer touchdown: the fact that I moved it solely due to respect and trust for the flyer who told me to
It's on the sides and about 5" wide and maybe? 6 oz cloth (hard to tell)
Starting from scratch, maybe you can build this plane a lot lighter than mine has become. VQ-38's (ARF's) had mass-produced Fowlers that worked on the same basic principle and worked really well, whereas mine required a ridiculous degree of tweaking and customization and TIME
I've always admired the way jet pilots mega-flare and seem to achieve both lift and air-braking
Maybe they're just better than I am at giving just the right amount of elevator at just the right time, but I've never been able to do that with a P-38. My approaches and touchdowns have always been shallow and fast and level and rate of descent almost purely controlled by throttle, except just enough flare to take the sting out of the last 6 inches. Just like you see in the pictures I posted.
I was surprised that moving the CG up > 1.5" resulted in a softer touchdown: the fact that I moved it solely due to respect and trust for the flyer who told me to
#1337
Join Date: Jun 2007
Location: ChristchurchCanterbury, NEW ZEALAND
Posts: 128
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Fowler flaps
Hi guys
Here is a pic of my ZP38 with its fowlers drooping.
If you look carefully you can see some evidence of the carbon cloth reinforcement on the RH boom {both sides) extending forward of the radiator blister position. This goes forward to just in front of the LE.
Regards
Dave
Here is a pic of my ZP38 with its fowlers drooping.
If you look carefully you can see some evidence of the carbon cloth reinforcement on the RH boom {both sides) extending forward of the radiator blister position. This goes forward to just in front of the LE.
Regards
Dave
Last edited by flyingpiggy; 09-17-2017 at 08:52 PM. Reason: added txt
#1338
Join Date: May 2006
Location: , IN
Posts: 37
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Thanks flyingpiggy for the images of your P-38, Will be home shortly from a business trip and post images of what I have. I see your getting to the point where its looking like a flying model shortly. Keep up the building! Thanks for your input, its greatly appreciated.
#1340
#1341
Join Date: Jun 2007
Location: ChristchurchCanterbury, NEW ZEALAND
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As a result of my first {NZMAA mandatory build inspection for "large models"} I was required to beef up the undercarriage mounting area - Just thought I'd share that.
Regards
David Read