Question 169: " Dear Mr. Jeff, Recently I bought the plans of a DHC-4 DeDehevilland with 97" of wings, of ScaleRcmodels but in the plans landing was put to frost fixed I want to change landig to frost fixed for retracts, the length of the main leg is of 6 3/4" with a wheel of 2 1/2" no this specified in the plans the weight of the model, I believe that it should be between 13 and 16 pounds, it is to use two engines .60 or 10CC. Could I indicate myself which marks and what landing type to frost it should use in this airplane? Thanks for attention"
Jeff: "I believe your best bet would be to go to the Robart or Century Jet website to see if there and any avaialble size and type retracts that would fit your plane. The nose gear probably will be rather easy to come up with. You can usually fine something close that will work. Century Jet has, in the past, special made gear to order. Robart is a bit diffferent in that category. Good luck. Jeff"
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Question 170: "Jeff: How do you like the CI Merlin ll? I am also drawn to the scale exhaust stacks. I am considering dumping my Nosen Kit with cowl and canopy 102" (no engine) and building the Don Smith 112 Mustang with the Merlin. This Kit was recommended by John Clark for the Merlin ll. Your opinion would be greatly appreciated. Thanks, Bill"
Jeff: "Hi Bill, I actually have no experience with the Merlin II engine. I had the Clark Spit, which mine had the Merlin I. The Merlin I was based on a twin Q-52 cylinder, while the Merlin II is based on Sachs 3.2 heads. I hear that the Merling II has more power than the Merlin I. I liked the engine and its set-up, but was not fond of the 3 blade prop selection. With the hub that Clark put on, you were relegated to his spinner/hub/prop set-up, which was a 22x8 3 blade. I just didn;t like the power curve it supplied. I always contemplated having a new prop hub made and going to a 24x12 2 blade for flight. But, in the end, I damaged the wing and sold the plane as is. The engine itself was a good set-up, I just didn;t like the prop combo. Also, John Clark is a terrific guy to deal with. Always eager and willing to gladly
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Question 171: "Jeff, I am building a Miester Corsair. Should install the Main gear with some toe-in or should they be straight. If toe-in how much."
Jeff: "Hi Dale, you will get varying opionons on this. I am an A&P by trade, and toe-in and camber become items of criticality for full scale aircraft. However, in my 21 years of modeling, I have tampered with both toe-in and camber. What I usually found is that it caused the wheels to bind up or to overstress the gear. Of course, this is varied based on the amount you dial in. Personally, I have found no use for it, and have not bothered with it for years. From my .60 sized airplanes to my 13 foot Corsair, I have 0 toe-in and have had no issues. The concept of toe-in is to mainly assist in ease of strainght taxi and relieveing some stresses in turning. But, with light weight models, I, personally do not see a need. I would not see a need for you to incorporate it on your Meister. Again, this is my opinion and not eveyone will tell you the same thing. Jeff"
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Question 172: "Jeff I am building a P51. an would like to do scale hinges. What is the best way to to do to do this? Bob"
Jeff: "Hi Bob, there are many ways to accomplish this. If you go to RCWarbirds.com and look up my Me109 "Frankenschmitt" project, you will see how I do it. I clean the trailing edge balsa off on the flying surface, so it is flush with the trailing edge. I then add 1/4 inch traingle balsa stock to the top and bottom of the surface to create a pocket. I then radius the leading edge of the flight control and center the hinge point at the center of the radius, removing some material to allow the surface to pivot freely. This allows full and free travel and is easy to do and gives the effect. Of course, there are many different type of "scale" hinging, but this is a general scale hinge that I think looks best and works best in flight, no flutter, etc. Check out my Me109 and you will get a better idea. Jeff"
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Question 173: "JEFF, as a 30+ year builder (mostly sig kits "bashed") of balsa planes, i feel really stupid. i have not a clue regarding fiberglass and wouldnt you know it, i got a CMP arf (p-26 peashooter) for christmas. question is, the fues feels "squishey" and i want to add some spruce stringers inside the fues. i have a steam box to prebend them, but what kind of glue is the best to hold them in place. the firewall and servo tray look like they were glued in with a "hot melt" gun.thanks for your help, dragging me kicking and screaming into the new century. mike s"
Jeff: "Hi Mike....sorry for the delay. I have been out of town. The glue will depend on the make-up of the fuse. If it is Epoxy based, which it probably is, I would scuff it and use some T-88 structural epoxy. You can get this at some woodworking stores or order it from Aircraft Spruce and Specialty. Other Epoxies, such as Devcon, etc. will work, but T-88 is darn near indestructable. If you have a polyester resin based fuse, you'll have to use a fiberglassing resin of some kind. the good news is that all of this can be avoided. I really like to use Methyl-Metthacrylate, available from Wayne Siewert Models....he is on the net and in Minnesota. It is not cheap, but with no prep it sticks to anything forever. It etches the surface and digs in to the glass. A similar product that I have never used, but hear is similar and good
is Aeropoxy from BVM models. I would go with one of the 2 latter options for ease of use. Good luck. Jeff"
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Question 174: " Jeff: I'm machining some super scale-looking wheels for my Bud Nosen Mustang, but I don't know where to get tires. Any suggestions on where I can get large scale tires that really look scale? Thanks! Tom"
Jeff: "Sorry for the late reply, I have been out of town. I have not had much luck finding scale wheels in he 8-10 inch range. The closest is to pick up some of the pneumatic compressor tires that you can buy at tool shops. You can sand down the tread on these and use various methods of burning in treads or just leaving smooth. It is a dirty job, but fairly easy and adds a nice touch. Jeff"
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Question 175: "Hi Jeff, I am in the middle of construction of a Vintage Royal B-25 Kit, which i found to be a very reasonable challenge. I have got to a point in wich i am looking at gear retract systems. but i am unsure about the type to use. I have looked at the Air retracts from Robart and they have the ones for the nose gear, but my problem is with the mains, They Retract behind the engines like the DC-3 and i can not find anything that would fit. do you have any suggestions that might lead me in the right directions. Thanks, Kevin T. "
Jeff: "I believe you may want to go with some spring air 400 series. You can install these so that they retract in or out or forward or backward.
They should make a nice fit. Check out Spring Air on the net. Good luck. Jeff"
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Question 176: "Hi, I am currently building a (small) P-47 thunderbolt from top-flite. At the site is a question if you can use mechanical retracts instead of pneumatic retracts. My reason to use mechanical retracts is because they are much cheaper. Can you explain me the disadvantages of the mechanical retracts and the advantages of the pneumatic? It would be verry usefull for my choise. Thanks Ruben"
Jeff: "Hi Ruben....for the most part, the choice it purely personal. With mechanical, you may pick up some weight with the additional servo size/power requirements (typical 180 degree servo) and size of battery you use, linkages, etc., over pneumatics, but very negligible. From my experience, I found mechanical less reliable, and more difficult to set up. I have had even worse luck with electric screw drive gear....but that's for another time. Mechanical: You need to spend a good amount of time setting up the linkage so that you get full travel with no servo binding, allowing for free operation without draining battery power thru a stalled servo. With the servo actuations, linkage arrangement, failed clevises and broken horn on the gear linkage, I
find it to be a high maintenance system. Let alone that a failure in any one of these can result in a folded gear and damage to your plane. With pneumatice gear, all you do is mount the gear and hook up your air lines to the valve with the servo. Unless you have a bind in your mounting plates or a leak in your air line, they will work every time, as long as you properly maintain them (required with any system). But, if you properly install everyhing and inspect for air leaks before flights, you typically have very little to worry about as far as the gear working for you day in and day out. Again, my personal opinion
and experience. Thx for the question....Jeff"
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Question 177: "Jeff, What causes servo chatter? I looked through some of your responses but found nothing on this subject. Maybe it is on another advisor section. Thanking you in advance. Laurence"
Jeff: "Hi Laurence....that's a big question. I am no electonics expert, but I know of several things that cause chatter...I have seen them all, I think. It could be any of these, and maybe more I don't know about. Typically, I have found that some servos chatter all by themselves, with nothing hoked up and no load on them. I think this may be the pot trying to center itself, but not quite right. I have found that most chatter is due from any one or more of the following. You also get chatter from a servo that is overloaded by a heavy control surface. Chatter can come from weak batteries, bad connections, wire on wire,
and I even had some wiring installation that wore thru the sheating and made contact with my retract unit.....and it really chattered. Metal clevises on metal control horns is another big one, a well as flying wires. I remember that a friend of mine had a Sig ST-A Ryan. Eveytime he flew over head, the servos would go nuts and the plane would recover. Scared him evey time. What we found is that he had 2-56 rod, bolted with metal screws thru the stab to suppert the tail. This created a cirle pattern of solid wire. He had run his antenna out the back of his airplane and thru the middle of the tail wires. We figures this was causing the signal to jump to the wires and scramble the reception. He ran the wire out the side of his plane to the stab trailing edge, and all was solved. Also, look for binding of cables, pulleys and rods. Without a dissertation of E=MC2, that's about all the knowledge I have with electronics.
Maybe others can jump in with the expertise. Jeff"
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Question 178: "Jeff. Thanks for answering my previous question. You say on page one Question you could send pics of your suggestion of how to build a good engine box, could you please send these to me. I am building a Meister Corsair, I ha ve a Sachs 4.3 to power it. Thanks Dale"
Jeff: "You can see the set-up on my 13 foot corsair project, found here on RCWarbirds. It is basically a mortise and pineed set-up like the furniture of days gone by. I don;t have any real drawings, but it is strong and fail proof and requires no screws. I learned it from an old furniture maker here in town. Jeff"
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Question 179: "Jeff, I am finishing my second Tempest 1:5 and thinking about next project which should be my first twin. My favorite is Mosquito from Bob Holmans plan (124). I would like to build the Mossie straight from the plan with no improvements from my side. I am far from deciding what kind and thickness of wood I should use. In case that the plan is pure enlarge from the Bryan Taylors one then I will rather go for Ziroli Black Widow there I can go straight from the plan."
Jeff: "Hi David, the 124 inch Holman Mossie is, in fact, just an enlargement of the 81 inch version. Therefore, there is some interpretation of the plans and wood size interpretation that will need to be done. As well, it is not an easy airplane to build. I did not build either of the Mossie's I owned. I bought the first RTF. The second I bought partially framed up, but the hard stuff was done. I do, however, have to rip out the homemade gear mounts and rebuild that area to accomodate my Unitract Retracts I have. If you love Mossie's, I think it is worth it, but the Ziroli would build much easier. Good luck.....Jeff "
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Question 180: "Jeff Missing root ribs for both wings on a Royal P-38 kit (old one). Know of anyone that has made a copy of these ribs. Would like to build this model someday, but my friend started it with the leading edges and root ribs, but lost them. I bought the model. Thanks, Ron"
Jeff: "I can't help on replacing, but I can offer some guidance on how to replace it. Take the "next door rib" (#2) and blow it up on a copier until it fits to the leading and trailing edge on the planform view of the wing plans. This will give you an almost exact replacement. You may need to trim/sand a bit to get it perfect, but when you use your straight edge in laying out the inwg, it will tell you right away if you need to add or remove material from this root rib. Jeff"
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Question 181: " Hi Jeff , I'm building the Top Flite Gold Edition 60 Corsair and am stuck at the retracts install point on the build. I've got the retracts dialed in to working great but need a little guidance on installing the servo / valve, air cylinder, and retractable tailwheel. Any pics and pointers would be greatly appreciated. Thanks, Tom"
Jeff: "Looks like a cool job Thom. As for the retract installation, the best thing I can offer is that you should do a search on RCU. There ar numerous topics in the warbird furum on installing these in to the .60 size TopFlite Corsair.....pictures and all. In words, I always lit to install the valve and servo in the wing, so that I have less connections to the gear. If you can fit the air tank in the wing, that is all the better.....no air connections, but I usually install my tank in the fuse. Then I only have one air connection from the tank to the valve. You will need to use a t-valve to tie he tailwheel retract to the air supply. I recommend taking an up line from one gear line and a down line from the other gear. Jeff"
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Question 182: "Greetings Jeff, How's the weather out your way? How can I get a set of the plans to build a 1/3 scale corsair. Who did the retracts and canopy for you. We have two 1/4 scale sea fury's almost ready to go I need a big twin got one ? Thanks, Sonny "
Jeff: "Hi Sonny, How ya been? I blew up Ziroli plans 65% to get my Corsair. The retracts are from Sierra (Darrell Tenny), and the canopy came from
MAtt Miller, in OH, that built a 14 fotter and had a mold. I thought you left the hobby to pursue street rods. I, myslef, have a 110 inch Seafury that I am painting now. Next winter is slated for a 12 or 13 foot Spitfire. A friend of mine has several big twin cylinder engines for sale. Hegoes by "gear-daddy" on RCU. Look him up and he can hook you up. Jeff"
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Question 183: " Hey Jeff, Repairing a foam core, balsa sheeted, fiberglassed wing. I suffered a crash of my Yellow P-47 which pushed the landing gear thru the wing. A small part of the leading edge was broken and bit's of foam have disitergrated. The rest of the plane is pretty much fine. 1. Question: Can you steer me toward any information containing repair methods and/or repair suggesstions on a a foam core, balsa sheeted, fiberglass wing? Looking forward to your advice. Thanks, David "
Jeff: "Ah, that's too bad David, but foam wings do make for easy repairs. What I will typically do is varied, based on the damage, but I have a Yellow Spit that suffered the same fate, as your P-47, last summer. I peels away all of the balsa in the damaged foam area. As you know, Yellow glues ply ribs to the foam to mount the gear on. If the ribs are still cleanly attached to the foam, but the foam is tore away (as mine was), then just test fit the foam/gear back into the wing until you get a good dry fit. Then use locating marks by marking with a Sharpie. Take the foam/gear back out and smear Gorilla glue on all of the exposed foam. Hit is with a small mist of water and place the gear/foam back in place. Watch this area as it dries, wiping away the excess glue as it expands. Do this to replace as much foam as you can. Once all of the foam is back in place, you can sand the excess Gorilla glue down and then re sheet that area with Dave Brown Sorghum, and then re-glass. You can replace the broken leading edge with a new piece of balsa segment and sand the leading edge to shape and re glass this. Best to span the crack with the new balsa leading edge. Another thing you can do, as needed, is to tape a couple of hacksaw blades and tape the far ends together to make a 1/8 inch wide blade. Cut in to the foam where you think it may be needed to add a 1/8 brace in the area of broken foam, to re-gain strength that you feel you may have lost. Use Gorilla glue again here. When I have gaping areas of foam missing, I fill with expansion foam and sand...just to give the balsa something to stick to. This is a generic repair to a foam wing. If you have pics or more info, I can work with you to get it repaired. Jeff "
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Question 184: " Jeff my question concerns then T/F P-47 and how to remake the retracts into a more scale position. i have not started the build yet but wanted toi compile notes and tips on contruction techniques to make as scale as possible with this kit. I have been to several sites but they were all dealing with smaller craft and the G/S kit is a different build than those. Also needed input as to the best type of retract to use as it is recommended to have them before the build is started. My other questions concerned the cockpit area and directly the canopy as i wanted to create a working sliding canopy. Paul "
Jeff: "Hi Paul, I would recommend getting a set of Ziroli or Vaillancort, or other scale plans that will show the more scale gear layout. You can use this as a guideline. Then it is a matter of setting down with your gear and drawing in the new gear rail locations on the Top Flite wing plan sheet and ribs. You can also use the ribs form the more scale plans as a layout to get a general idea. Take the gear ribs from your Top Flite kit and trace them on to some poster board paper to use as a working tool. Once you have the layout and dimensions all marked on these poster board ribs, use them as templates to cut new gear ribs from plywood. As for gear, you can use Robart or Sierra, but you will need them before ou start. There are various models to choose from, but you will need them in hand to do this right. I prefer Sierra, but I believe a set of Robart 151's may make the job easier. For a sliding canopy, do a search on RCUniverse...there are many topics on the subject. Most people use brass or plastic channel. Good luck. Jeff"
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Question 185: " JEFF : hi, i'm from the uk, am 22 and just finished building my first large warbird, is a 1/7th scale dauntless. (70" span") I was just wondering how to get the CG spot on, how to test it and know it is correct before I commence practice take off runs. I have picked the plane up, wing tip to wing tip with two people so in effect it is balancing on its wingtips, and once he plane settles it is about 10 degrees down on the nose, off the vertical. should the plane balance on the vertical or be slightly nose heavy? I have read reviews on scale warbirds nosing over on takeoff/landing and I want to avoid this. please advise. Regards Wesley "
Jeff: "Hi Wesley, there are a few different ways to find the CG. The plans should show them, and these are usually conservative The best way is to find the maen aerodynamic chord (M.A.C.), and take 22 percent of that. Now, you will hear 25, 30 or 33 percent, but trust me, I recommend with a warbird that you go with 22 percent for intial flights and adjust back as you get the feel of the plane. Save the 28-33 percent for the aerobatic stuff. You should balance so it is just slightly nose low...you don't want the nose to fall to the floor when you balance it. Here is a good site describing how to find the M.A.C. > http://moleski.net/rc/WingMAC.htm
Now another conservative and easy way to achieve initial balance it to measure the chord (leading edge to trailing edge) at the fuse sides
(you can extend this point/line out to the tips if desired). Take 25 percent of this measurement and balance slightly nose low again, on this point. Here you can safely take 25 percent as you will always be forward of the M.A.C. CG when doing this. Again, you can adjust as you fly and become familiar with the plane's characteristics.
In either case, you should not have big nose over problems. A common nose over problem is usually due to the wheel axle center line lying too far raer of the wing leading edge. Make sure your configuration is accurate. On warbirds, even perfectly balanced, it is not uncommon for the occassional nose over. the fact is, with the need for gear placement in the wing, you do not have the advantage of aerobatic planes where the gear lie far ahead of the wing leading edge. So, and occassional nose over can be expected, but is really rare if set up properly and flown properly. Jeff"
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Question 186: " I am scratch building a 1/5 scale Spitfire Mk. XVIII. My drawings show 20 mm cannon on each wing with a rounded stub protruding from the leading edge adjacent to the cannon. What is that? Charley Roesch"
Jeff: "Hi Charlie, that is a cannon blank. The Spitfire was equipped to carry 2 cannons per wing. Typicall, they only flew with one cannon installed. They capped the empty cannon bay with a sheet metal plug, known as a cannon blank, to keep the airplane claen and cut out drag. Jeff"
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Question 187: " I am looking at buying the Sportmans Aviation F4U Corsair. The manual suggest the biggest four stroke to use is the Magnum 70. I want to put a Magnum 91 4 stroke in it for more power and speed. Can it fit and will there be much mods? I looked at the specs for each engine and they are very close. A little trimming does not bug me that much. Mike "
Jeff: "Hi Mike, if you don't mind doing the trimming and modifications to make it fit, then there is no reason you cannot go with it. I do believe it is way more power than you would need, but if you like big motors, then there is no stopping you. You could sure swing a nice sized 3 bladed prop, that would add to the appearance of your model. Just make sure that you do not make the plane overweight....you may need to add tail weight. Good Luck....Jeff"
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Question 188: "Jeff; Have been think of making molds for a 1/5 Hellcat, and while reading on the subject, found that the full-sized ship had 3 degrees of downthrust in the engine. Would such a thing be necessary (or adviseable) in an r/c model of this size? Also, was the horizontal stab really as thick (top to bottom) as it appears on some 3-views? Thanks for the help! See you in Owatonna at the NMA Fly-in. Jeff "
Jeff: "Hi Jeff. I am thinking that the 2-3 degrees of dowhthrust may be needed on the hellcat. What tends to happen on a wing such as the hellcat, Seafury, Texan, etc., is that, with the flat center section and dihedral in the panels, the angle of incendence/lift of the outer panels causes the plane to want to climb. I don't know the aerodynamic property causing this, but I have found it to be the case. I did not add down thrust on my Seafury, and it climbs like a homesick angel. I went back and added about 2 degrees of down thrust to help cure the problem, but it looked bad since I hadn't built it in. So, I took it back out and just trim for it. As for stab thickness, I have not really studied the hellcat, so cannot comment on chord thickness. Best to scope out a full scale, which is hard here in MN"
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Question 189: "Jeff: My buddy is going to Ft Pierce today to pick up a completed Ziroli P-40. It has the same "skull graphics" as yours (as pictured on RCWarbirds.Com). If possible, could you tell us how to get more info about the group/squadron that used the skull? Many thanks, Lloyd
Cape Coral, FL Cape Coral R/Seahawks"
Jeff: "Hi Lloyd....the skull is from the 80th fighter group, comprised of the 88, 89, 90, and 459th squadron, 10th Air Force. Based in the CBI theatre. I like the unusual scheme, as too many seem to be done in the shark mouth....eye pleasing nonetheless. Here is a good website: Jeff" http://www.talkingproud.us/HistoryBansheesE.html
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Question 190: "Jeff I need your help. I have a RCS 215 radial engine (11.7" diameter) that I am now looking for a kit or plans for. Never knew it would be so difficult to match a plane to a engine. So far I have only found plans for a P-47 and a Seafury due to the large diameter of the cowl needed (at least 12"). I also know that Stuart Mackay has a FW 190 for it, but it is quite expensive and freight is to. I would prefer a fiberglass fuse, but will build if necessary. I was hoping to find something like a T-6 or a Zero just because of the wonderful flying characteristics. Do you know of any companies or people that might offer fiberglass fuse to meet these needs? Thanks for the help. Doug"
Jeff: "Hi Doug...as you say, the 101 Bates or Vaillancort Seafury would be a good candidate. Brian O'meara is flying this set-up in a 101 inch Bates Seafury. As far as a Texan, I don't know of any out there, altho you could always enlarge a Ziroli to fit and make the cowl up yourself...quite easily. Sierra could probably set you up with gear, if not Robart. For a Zero, look into the 118 inch Meister or enlarge a Ziroli design and use the Meister accessories. In all cases, you would have to build them up. Another thought is a large SBD Dauntless in the 10 foot span range. The 118 inch Meister is a dream Zero to fly...I owned one. Good luck. Jeff "
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Question 191: "Jeff, Last winter I was given a partially completed model of a B-17. It's 25 years old and needed a lot of TLC to get cleaned up and back underway. Construction is balsa and balsa planking. Wingspan is 78". The original intent was control line, but since I haven't flown one of those since about 1961, I decided to make it a static model. I picked a B-17f, 124554, The Mustang, of the 43rd Bomb Group in New Guinea just to be different. Silly me. Not a lot of info, but I'm getting there.
Anyway. I'm having trouble shaping a nose one, top turret and ball turret. Any ideas or info where I can get things? I'm also trying to get the visible interior as real as possible. Any help or ideas you can give me would really be appreciated. Thanks, Don"
Jeff: "Sorry for the delayed response. I had a fight with a G-23 propeller and have been laid up with a damaged hand. You may want to look in to a MArtuka/Royal kit. Their B-17 was 77 inch and sounds close. Also, you could always shape these from balsa or foam and have them pulled. Jeff"
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Question 192: "Jeff, I've been out of R/C for a number of years. About 20 to be closer to exact. I flew mostly pattern and built most of my planes from scratch even cutting wings from foam. We drew and designed our planes then built them. My real passion even then was in warbirds. Giant or 1/4 scale was not real big yet. The last plane I built was a small 69" wingspan Top Flite .60 size Mustang that I never finished. This was my only scale warbird. I'm thinking of finishing it and working my way back into flying. I have seen a few guys at the local club flying 1/4 scale and I love it. What would you recomend as a first build on the 1/4 scale size P51. Thanks! Sean"
Jeff: "I would have to offer the Ziroli P-51 as a great candidate (www.ziroliplans.com). Since you have building experience, it should be no problem. You can do an all wood built up version. There is also a glass fuse option avaialble from Ziroli that would cut your building time considerably. If you wanted foam wings, you can contact Dynamic Balsa (www.dbalsa.com). The Ziroli is a 96 inch span and flies well on
a 4.2 or larger engine. There are many more options out there. But, for money, quality and flying status, I think it is tough to beat a Ziroli. Another candidate is the 112 inch Don Smith (www.donsmithplans.com). Much more labor intensive and I really have no experience with it. A friend of mine has built 2 now and I know that it also flies very well. The only other real candidate is the all fiberglass kit from compositearf.com. It is a 102 inch span, I believe. There are Nosen kits out there, but by far the most work out there. In the end, I would have to recommend the Ziroli P-51. Good luck. Jeff"
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