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Old Apr 03, 2009, 12:50 PM
MPP
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GUILLOWS CORSAIR F4U 1D With Rotating Retracts

I have been asked what’s next? so here it is, gonna build me a Corsair. I pulled the wrap off the box last night and opened her up. Looks like a nice kit and has two cowls for an F4U-4 and the F4U-1D versions. So with the introduction of the new HL scale three blade prop I put together a power package before I opened the box and will opt for the F4U-1D. I also have a pair of Robart micro retracts that I want to modify to 90 degree, per Ron Kay’s 90 degree retract modification

Here is the plan:

HiMaxx 2015-5400
HL 3 blade 9.5” dia. Pitched to 10” to start
4.5:1 Cobri gear box (gives me 140 Watts to play with)
18 Amp ESC
Rotating retracts
3S 1320 battery
AERT
Modify the airfoil and incidences
Covered with Doculam (have a ton of the stuff)
Under 20 Oz.’s
Have fun and learn new things

For reference here are a couple of threads
LS427 Conversion
Captain Mike's conversion
Backer's conversion
Rocketman209's conversion

Let's see what happens,

Mark

Corsair Three Blade Run up (0 min 33 sec)
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Old Apr 03, 2009, 01:24 PM
SVX
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Fantastic, I'm in. Can't wait to see what you come up with. Are you sheeting or leaving it stringers?
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Old Apr 03, 2009, 01:45 PM
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Very nice Mark cant wait to see this ine flying. subscribed
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Old Apr 03, 2009, 02:24 PM
MPP
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Hey Dust,
Tanks for jumping on board. I think I am going to sheet the gulls to the Landing gear on the wing. With the fuselage I was thinking of insert planking the nose and wing saddle area leaving out a majority of the stingers in the back but cap strip what’s left. Rudder and elevator a combo of frame and 3/32 sheet. I found with the Thunderbolt fully sheeted the weight crept up pretty quick. I would love to have this come in at 15 Oz.’s. It’s aggressive but I think it could be done with a few learning’s from the T- Bolt.

Captain,
Welcome aboard. I guess that is what you would say to a Captain? I know you are still building your Guillows Corsair and I was curious if you guys made any more progress on the 90 degree retracts from Zeke? I am going to give Roy’s modification a try as it does not seem to be that difficult. I have always wanted to get a set of those retracts from Parkscalemodels though. Oh well let the fun begin!

Mark
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Old Apr 03, 2009, 02:55 PM
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Hey Mark:

I was wondering what your next project would be. This should be great. I look forward to following your progress. It will be great with retracts. I think you will be very happy with how this flies if you can keep the weight to 15-16oz if my easybuilt spitfire is any indication.

A couple of ideas.. 1) you might want to consider making the tailfeathers from depron covered with silkspan and wbpu. This makes a nice light structure that can be spraypaited. This being said, tail weight may not be an issue with respect to CG given the schnoze on this plane. 2) what type of airfoil does the corsair have? I am no expert on this, but I think you will be happy with a semi-semetrical airfoil rather than a flatbottom airfoil. It is pretty easy and worthwile to re-plot your airfoil with Profili if you have it.

Anyway, I am excited to follow your progress. I am sure you will end up with a great looking plane.

Alex
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Old Apr 03, 2009, 11:08 PM
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Mark I haven;t really gotten that far on mine. I have been waiting for a few mods. The wing is getting a complete revision for the retracts as well as the functioning flaps. I dont think they will be needed but fun to have. Make yours a bolt on wing so when the new design comes out you an swap it out. It will come with the retracts as part of the wing.
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Old Apr 04, 2009, 09:18 AM
MPP
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Some times you get lucky

That sounds great Mike. Thanks. I look forward to your B25. Let me know when you are ready for maiden and I will bring the video Camera.

AS I dove into the kit last night I found that it probably dates back to the late seventies or early eighties. It has wood for firewall and such, not the crappy vinal. The brochure includes out of production models also.

Now I am feeling like I need to build this per the kit and it's included parts. I am sure there are more of these old kits out there. Brought back memories as I cut open the plastic wrap that was old and crappy. It felt like a discovery of sorts or opening a piece of history.

Too bad, the box is open now and it has finally made it to the building board. Who knows how many peoples hands this may have passed through and now it is time.

Alex thanks for the ideas. You are correct in that i am not too worried about being tail heavy. The airfoil I was just going to thin a bit on top and add to the bottom makeing it more semi semetrical. What was the SBD profile? I imagine it was the same. Hope you can start the Tempest soon, You are going to love it. Oh and I think I will have to add the bomb drop per the plans

Thanks,

Mark
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Old Apr 04, 2009, 12:11 PM
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Hi Mark, nice job...I have the SBD kit that i started( imagine that) I really like the new props..and I love using gearboxs..I am watching
Scott
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Old Apr 04, 2009, 07:07 PM
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Hey Mark:

I have seen several threads where people have done similar modifications to the airfoil to make it semi semetrical with good effect. I bet your plan will work just fine. The SBD is one of the few guillows kits that comes with a semi semetrical airfoil so there was no need to modify. It is my understanding that the flat bottom guillows airfoil along with the positive wing incidence results in the plane tending to porpoise in the air as this configuration was designed for free flight under low power. I had this problem with my guillow's stuka before I knew about all of this. (I bet you knew all of this already!)

There is something very 'visceral' about these kits that really appeals and really brings you back. Sure there are a lot easier ways to skin a cat, but something about making these old kits come to life and fly infinatley better than anyone can imagine is appealing. I look forward to following your build. A bomb drop would be great.

Alex
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Old Apr 05, 2009, 10:12 PM
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Well Mark you may just motivate me to build this plane, since it's the only one in the series I haven't built. Finally got back on my SBD with retracts, and have it to the point where I may actually try it. Still have to brave the Smokin' Beaver style 200% enlargement of the 17" Guillows Stuka though. Got the canopy/cowl/wheelpants donated by a really nice guy for that one, who gave me a partially complete kit of the larger Stuka, after I started the scratchbuild. Coincidentally, I just flew my 200% Guillows Chipmunk scratchbuild today. Always a good flyer. The P47 is still a good flyer too.

BTW, my donor Stuka parts kit for the 200% scratchbuild was also an old era plywood parts kit too. Was amazing to not see that cheesy vinyl crap.

As Alex stated about not going flat bottom, my P47 has a semi-symmetrical airfoil, and the Stuka does not have the stock flat bottom airfoil either. I wasn't aware that the Corsair did not have the semi-symmetrical airfoil like the SBD and Hellcat.

Mark, as you were stating, I simply added a bit to the front bottom of my second P47 wing build to raise the LE , and a bit of reshaping on the LE to make it somewhat semi-symmetrical, along with decreasing incidence by moving the rear wing saddle up by 1/8". The wing is not to heavily modified from the stock wing, and it flies very well. The Chipmunk airfoil is similar, and only slightly modified to not be a completely "flat bottom" airfoil. It has flown well inverted too.

Good luck, I think you'll have a good flyer with the Corsair.
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Old Apr 05, 2009, 11:31 PM
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G'day guys,
I'm in for a look too
That's one mean looking powerplant.

Good luck with it mate.


Phil

Now posted onto 'The List' too btw.
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Old Apr 06, 2009, 10:34 AM
MPP
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Going Old school

Scott,
I am a big believer in GB’s when swinging multiple prop blades. Three blades you could go with an outrunner but the whirl of the GB will be pretty cool on the Corsair. BTW you are not allowed to work on your SBD until you finish your Tempest .


Alex,
I am pretty sure that this is flat bottomed per the plans but I will give it a check. I picked this up on Ebay and I just missed getting the SBD. That sure looks like a nice kit and a good flyer from what I have heard. Do you ever fly yours anymore? Thanks for your thoughts, much appreciated Might have to do the Rekitter bomb drop modification.

WT,
Your Chipmunk is fantastic. Stuka also looks great. I think you should be pretty good on the SBD, good luck and let us know when you getter done. I am going to go with the same method as the P-47. Thanks for your help on that one BTW. I haven’t really looked at the wing yet and what I really have to work with, but should be similar minus the gull wing.

Phil,
Thanks for peeking, I meant to get a post over on the conversion thread, thanks for listing this. Good luck on your Zero and P-40. The P-40 still eludes me. Someday.

I did some more work over the weekend. I decided that I would go “old school” on this kit and use the lost art of insert planking. I did the lower cowl and started the wing saddle. Again this kit and it’s age make me want to use the old techniques I learned when I first started building these many years ago. I will be using the supplied wood and as many of the parts as possible. Also the plan “features” call for sliding canopy, retractable landing gear, flaps, folding wings and Bomb drop. I have already installed the canopy slide frames and the bomb drop is under consideration if I am within weight budget. Folding wings sure sound cool but could be a big risk for a flying model of this size. You know, who wants folding wings in the middle of a flight. Flaps are a no go and the retracts will be a removable mod.

That’s it for now.

Mark
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Old Apr 06, 2009, 12:19 PM
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Hi Mark,
would be nice to see it with retracts. I did not put retracts on main. And suddenly I didn't captured success flights of it. I had fully sheeted fuselage, but wings was covered by tissue from the kit. Flown it with cheapest power combo (tower pro 2408-21T) which did good job with 9x4,5 9x7 props. I think it would fly with 8x4 3 blade, but I dont have my corsair anymore.
It was flown very well but on full throttle it always had nose up - because of positive incidence of the wing and bottom flat airfoil.
Will you change airfoil?
I think Herr Engineering (SIG) have same size Corsair but they made airfoil better.
Next time if I will wish to build Corsair again, I'll try to build it from Herr Engineering Kit, but Guillows have better details in kit I think with modified airfoil it would be good.

Good Luck
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Old Apr 06, 2009, 06:06 PM
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Quote:
Originally Posted by nikita_flyer
Hi Mark,
would be nice to see it with retracts. I did not put retracts on main. And suddenly I didn't captured success flights of it. I had fully sheeted fuselage, but wings was covered by tissue from the kit. Flown it with cheapest power combo (tower pro 2408-21T) which did good job with 9x4,5 9x7 props. I think it would fly with 8x4 3 blade, but I dont have my corsair anymore.
It was flown very well but on full throttle it always had nose up - because of positive incidence of the wing and bottom flat airfoil.
Will you change airfoil?
I think Herr Engineering (SIG) have same size Corsair but they made airfoil better.
Next time if I will wish to build Corsair again, I'll try to build it from Herr Engineering Kit, but Guillows have better details in kit I think with modified airfoil it would be good.

Good Luck
Rotating retracts would be quite a job. The only one that really "asks" for the retracts is the Dauntless, as it has beautiful molded wheel bays. You're right about details, as the Guillows look incredible with all the molded parts when done right, compared with others.

Mark and I have both been down the high-incidence, flat bottom road with the P47. The incidence does need relieved a bit, but not as much as some would think. The airfoil doesn't need to be all that drastically reshaped to relieve it of the "Aquilla" issues with non-Phillips entry. Padding the front roughly 1" of the wing bottom with 1/16" sheet and tapering does the job. Tapering the sheet toward it's rear will in essence give you a slight undercamber, which seems to work well. You end up with a light undercamber such as on the E222, for example. Along with this padding, shape the LE upward a bit for a better Phillips entry, and as Mark stated, reduce the thickness of the airfoil a bit, by reshaping the top. I did this on the P47 with good flying results.

Pardon for the semi-hijack Mark
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Old Apr 07, 2009, 10:30 AM
MPP
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Nikita, The Herr looks like a nice conversion. Maybe you could build it and order the plastic parts from Guillows to dress it up. Or try and modify another kit. Yours did fly so you are close. I would say give it another try.

WT, no problem, that is a great explanation. I don’t think I will be as scientific when I get to the wing but I will try to emulate the P-47 incidence and rib modification. I think I raised the TE of the wing by 1/8-1/4” and raised the LE of the horizontal stabilizer by 1/16”. I also cut all new ribs with a semi symmetrical pattern and with the elliptical wing blended a washout of ¼” at the tips. Guillows P-47 conversion

That looks like a nice molded in feature on the SBD for the retractable landing gear. I must say the P-47 with its wide stance is a good choice for retracts also. I still want to try out Ron Kays 90 degree rotating retract modification I think it is a good solution, maybe not as aesthetically pleasing but gets us to a more scale look and the gear tucked up where they belong.

I am also now planning the battery/ equipment hatch. I am not sure but am considering going from B-3 to B-8 with the cockpit/ hatch as one piece. With the long front end I think the battery is going to be behind the CG. Just a guess but leaves me room to play a bit. With the insert planking on the bottom of the fuselage we should have plenty of strength.

Mark
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