Question 121: "Twinman, After reading your reviews on the VQ P-61 ARF I ran right out and ordered one. As I await delivery, I am making plans on how to put it together and could use some of your sage advice. First, I plan on using two OS 91FX engines (already have them), with the three bladed props. I noticed that you mentioned the YS's in the proto were mounted inverted which is in direct conflict with your "rule # 2 or 3" about twins and inverted engines. Will there be any problem with mounting them upright?
Second, I would like to make it as scale as possible. I have picked a P-61B-15 to replicate which has split Main Landing Gear doors and will need some attention to actuation. I think I have a handle on this part, however, I see that VQ is recommending Spring Air 400 series for retracts. I have no experience with Spring Air, but understand that they are "spring down, air up". If that is so, they won't work with the scale action I am looking for. Any recommendations? Thanks in advance, Tom Guptill"
Twinman: "Hi Tom. The prototype in the VQ reveiw used Super Tigre 90's and it works fantastic. Yes, the inverted is NOT a good idea, but VQ built it this way and yes, one did flame out in the air. Naturally, it was with me at the controls..Panic, does not cover the feeling, but you will like the single engine response and flying, but I did not want that experience on the prototype. Yes, upright is better for many reasons, including safety at starting. Expect the engines to stick out 1/4 inch. As for recommendation on landing gear, any good system will work, but remember this is an 18# plane. Do not go cheap on the gear for this weight. Spring air is air up and when the air pressure is released springs lower it. The idea is that if you lose air pressure for whatever reason, the gear will
automatically lower. There is a company in Canada that supplies sequencing valves to do almost anything you could wish for door control. Name of company is Ultra Precision at http://www.up-1.com/ The prototype has built up doors, but production will be fiberglass. Good Luck and send pictures, Twinman,
PS Just heard from VQ......The P-61's are on a ship and headed this way."
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Question 122: "Dear twinman: I am currently looking at the Wing Mfg. A-26 as a first real twin (have flown a profile 38, very fun). I plan to use a pair of Saito 56's running 30% heli fuel (they love the stuff). Should this be adequate power? What props would you reccomend? Thank you for any insight. Graham"
Twinman: "Hi Graham, That is very good power. I would suggest that the props be what you have been using on these engines for a start. I would not suggest three blades at least in the beginning until you have some time with the plane, then switch to three blades, which are not as powerful due to loss of efficiency. You do not want to under power this plane, but it flies well.
Good Luck, Twinman"
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Question 123: " Just found your site which is fabulous. Fly scratch built P-38, 70 wingspan, OS 50's 9.5 lb, flaps. 108 engine out landings. over 1000 flights. Am interest in more detail regarding your gyros. Tried gyro years ago on flying wing, not much help. Still working on flying wings, think knowledge/experience with gyros on twin would help me with gyros on rudderless aircraft. Use Futaba 8 and 9 for twins, either work fine. Good setup for engines detailed on Futaba site under "9 cap faqs" section. You have really said it all about twins. Thanks. Dick"
Twinman: "Hi Richard, Congratulations on engine out landings on a P-38. Part of your success, besides expert flying skill of course, is the relatively light weight of your plane. At 9.5 pounds, this is much lighter than the various other versions of this plane, including the one's I have built. While I have not really gone into flying wings, this is the part of this hobby that makes it fun for all. To share experiences. When you tried the flying wing and gyro. How did you install the gyro and what functions did it control? I would imagine that directional stability is a primary concern. I think they call the end flaps on the B-1 Spoilerons. Have you considered to install a twin input and output on that function, but install it so that it functions as a rudder?
Another idea. I wanted to experiment with hovering with at twin. One big problem with this, is that the rudder is not in the direct wind blast of the engines. I used the above gyro installed between the engines and the receiver. Each engine had it's own channel and the rate was adjustable from the transmitter. The gyro actually cycled the twin throttles to the engines to aid in hovering. I did not actually do this more than a few time, just to prove that it would work, but there was a definite improvement in hovering ability. Perhaps that concept would aid your flying wing designs.
Keep us posted and good luck, Twinman "
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Question 124: "Hi George I am in the process of putting together the Giant Scale planes mosquito 73 ARF, the book calls for 2C 25-32, however this is going to be a 11-13 lb airplane. I have heard varied advice on this being lots of power, however, I am concerned. What are the dangers putting in bigger Powerplants. i.e. OS 46 FXs. Thanks, Robin, Edmonton, AB"
Twinman: "Hi Robin, Our buddies in the North do not have the lawyers looking to sue at the drop of a hat, so advice on exceeding the manufacturers suggestions, for us "Southern Cousins" must be tempered. We all do not want to get hurt or hurt others.
If you exceed the recommendations, there are several potential problems, including wing failure, engine mount failure, and control surface flutter and or failure.
Do you have room for the fuel tanks? Bigger engines mean more fuel and more weight. Your warranty on the plane is gone..Period.
Now, one good point of larger engines and a reduction of stress is to go the scale route and use three blade propellors. They are not quite as efficient and so reduce the thrust some. You would need the larger engines for these props.
If you lose and engine on take off, the plane will snap roll. If there is more power, the snap will be faster and more violent.
Now, if you lose the plane in flight, the extra engine will be able to fly the plane, as long as the rudder is large enough for the offset thrust. I have not flown this plane, and so I cannot say whether it will be controllable with one engine or not, but with a weak engine, it will not fly. Remember, if it takes the better part of both engines to fly the plane, and you lose one, you do not lose 1/2 of the required flight power, you could lose 80%.
Do I over power my planes. In a word, yes. I do reinforce the structures almost religiously, but in and ARF, this is difficult at best and almost impossible. I have flown scale planes that are "Scale Powered" and in a word, BORING.
You do have the left stick to control power and do not have to tear the wings off.
Hope this helps. Use commons sense to protect yourself and others.
Good Luck, Twinman"
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Question 125: "Friend George I always look for to use Rudder + Aileron coordinate and. Now that I am arriving at the end of the assembly would like to know, in case that the friend knows, which would be angle maximum for ailerons and flaps in the TigerCat."
Twinman: "Hi and welcome to rcwarbirds. As a general rule,for normal flight 30 degrees deflection is approaching surface stall, go further and you're getting as much (or more) drag than aerodynamic control. If you don't have the reaction you want at 20 degrees the surface is most likely too small. It just popped into my mind that flaps are an exception to the 30 degree "Rule." For added lift 30 degrees is still about right, but they are also used as air brakes at times, for that 50 or 60 degrees is fine. Hope this helps. I had to discuss this with a friend in Florida who owns two such planes. and am using his information. Good Luck, Twinman"
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Question 126: "Hi there I wonder if you can advise me
Im an experienced single flier in the UK mustangs, spitfires, 3ds, sports, WW1s, tiger moths etc etc and now, I want to fly a twin. I have an as yet un-started Top Flite DC3 thats my twin of choice as I am a builder as well as a flier and I like Top Flite for value for money, size and near scale appearance. I have read you article, and got to the end sorry, you didnt put me off. I have found it very difficult to buy any other twins more suitable to learn on in the UK Can you suggest another twin ARTF would be fine that would be a better trainer that I could get hold of in the UK. I was hoping to run the DC3 on OS52FSs, so ideally it would also be a suitable test bed for those engines. I was looking at the Air Loisir A26 but maybe your advice would be against this one too
Thanks in anticipation, Jim"
Twinman: "Hi Jim, How are our British Cousins? Hobbico is bringing back the Twin Star arf and that would be a possibility.
Contact Northeast Aero at http://www.ne-aero.com/. They have a fine line of kits that are quick to build. Or BASH a kit into a twin. One's I have done are the Ugly Stick and even the Kadett. ( Note, Kadett is boring...too easy to fly) If you would like to tackle the idea of bashing something into a twin, let me know, and I can send you a personal list of suggestions to do it easily. Welcome to the twin sanity club. Twinman"
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Question 127: "Hi George, I hope you can help me, I am building a small Cessna 310 and was hopping to use two Thunder Tiger 36Pros for power but I only have enough room in the wings for 4oz tanks. Which would only give me about five circuits before it
was time to bring her into land (not much fun for me as I like longer flights). So my question for you is weather there is some way to place a third tank in the fuselage and pump the fuel out to the wings, and if this is possible what is the best way of doing so. I hope you can help Glenn Wilson."
Twinman: "Hi Glenn, Just so happens that I have just finished a prototype B-17 evaluation that needed exactly that set up. If you will look here, you will see the article about one tank and four engines. It should answer all the questions as to how to do this. Many people have asked this, so when I got the chance to actually try it, I did and it does work. The prototype B-17 is still not in production, but I flew it today again with the fuel pumps and it works. I ended up backing out the fuel pump pressure regulators one turn, but be careful, too much out and the pumps can be damaged. There are other systems of doing this, such as Iron Bay and Cline fuel systems. They use crankcase pressure to pressurize the main tank and regulate it at the engines. The Perry pump system also uses crankcase pressure, but only to operate the pump. Good Luck, Twinman"
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Question 128: "Hi George, I've been looking all over the web for a kit or plans for a P-61, about 1/12 scale. Would you know of anyone and their addresses or web sights so I can get in touch with them? I read your review on VQ's P-61 and wonder if a smaller version would fly as good as there's? Looking forward to your reply. Thank you, Bob"
Twinman: "Hi Bob, I did a quick search on the P-61 and did find smaller plans at http://www.nexusonline.com/pages/nexusdirect.cgi is a control line at 50". Here is another one http://kitcutters.com/Nex/NexP61.htm or http://www.parkerinfo.com/plans/applans1.htm
No, I am sorry, smaller planes do not fly as well as larger planes. It really does not matter what model. The larger planes are easier to see,react slower, and are more scale like in action. You will also find that in most cases, the larger planes have lower wing loading, and so are easier to handle. Keep us posted. Twinman"
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Question 129: "Hello from South Africa and thank you very much for all the advices you give. We are flying at 1500 meters above see level and i just bought the VQ P38 kit. The KMP P38 is also flying at our club, it is powered with two OS 46AX (APC 11X6 prop), i flew this kit and it flies beautifully and fast bellow half throttle. I am worried about the VQ kit because not only the wing is thinner but the wing loading seems heavier. I am planning to use two saitos FA82a with three bladed prop.
- Do you thing this might be enought for scale flying ?
- Is a 180°proportionnal servo a necessity for the flaps ? Can't find any here !
- Where can we see pictures your's flying ?
Thank you for sharing your experience Eric"
Twinman: "Hello Eric, The VQ is much more scale than is the KMP. No, you will not have any additional worries. I do not have experience at that altitude, so a bit of what I might say is based upon experience. The engines you have are fine, but I would go for two blade props for better efficiency until you have a better idea of performance at that altitude. Two blades are slightly more efficient. No, they do not look as cool.
I don't care whether the plane is a KMP or VQ, BURN IN YOUR MIND. Make sure the engines are reliable. An engine out on a P-38 is downright dangerous due to the design of the plane. The VQ engines are closer together as scale and so a little more forgiving, but DO NOT GET CONFIDENT on any P-38. Always....ALWAYS use two or more people to fly these things and do the vertical test for 10 seconds before every flight. Wing loading differences are not a big deal and not that much different. Don't forget the VQ has the larger and scale fowler flaps.
It is possible to use standard servos with longer arms for the flaps, but some cutting for the longer arms will be necessary. Airtronics is the only manufacturer that I have heard of that offers proportional 180 degree servos. The landing gear servos are not proportional, but can be used anyway but not in partial flap configuration. Plan on a long take off roll. Not so much for power, but a good idea for maximum control upon take off. Most P-38's do not just lift off, You will command them off the ground.
As for video of flight, you can go to VQ's website. Personal video, I do not have .....I shake too much when flying these things.
Have a good day, Twinman"
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Question 130: "I would like to locate a nice P-38 kit or ARF I am not interested in the "profile" version though. Would you have some links or suggestions? Stewart "
Twinman: "Hi Steve, That is a tall order. The P-38 kits are few and far between, but I will try.
VQ Models and KMP also do the only arf's. I thought Robart had one, but cannot find it.
If you go to VQ's site that can link from the rcwarbirds site or http://www.vqmodelaircraft.com/index.html.
You can see both the KMP and VQ compared.
Hope this helps. Welcome to twinsanity.
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Question 131: "Thanks for your excellent advice!! Where could I find a plan for a twin Stick? I think this is the best way to start with twins? Thanks for any help. Hennie"
Twinman: "Hi Hennie The fastest way to just convert a Ugly stick into a twin by adding nacelles and lengthing the wing 15% to reduce wing loading. Or go to a new company called Cedar Hobbies at http://www.cedarhobbies.net/index.php?id=product_desc&product=5 and get one already built as an arf. If you go to our sister website at rcuniverse and the twins forum, you can see the review of this plane there "New Twin Arf". I really think you will be glad to get the experience first and then go for the scale birds. Good Luck, Twinman "
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Question 132: "Hi Sir, I'm building a 72" PBY Catalina (flying boat version, without landing gear). Specs are about 800 sq./in. wing area and weight is unknown but should not be more than 10-12 lbs. The plan call for .30 to .35 engines The nacelles are very small and clearance to the fuselage does not allow using more than 8" diam props. I plan to use two .32 size engines with 3-blade 8X6 props. I will install one 16oz tank in the fuselage with VP-30 pumps on each engines as mentioned in your article on that subject. Since I prefer not to modify tha plan or the scale apparence of the plane, I'm limited to 8X6 props. Do you think I will have enough power to take-off from the water with the above setup ? The performance I'm looking for in the air is slow scale like flying but I don't want a too long run for take off. OS .32 SX is considered, any other suggestion ? Thank for help. Dominic"
Twinman: "Hi Dominic, The B-17 in that write up is using Magnum 32's and I orginally used the Master three blades 8x6. While it will work, you should know that with 15% fuel the engines turned 14,000 rpm. I have since changed to Master 9x7 props for a better 11,000 rpm.
As far as power, you should be fine. This is a strong pulling set up, but watch out for the rpm. While I have not searched all the available propellors to keep the rpm down in only 8 inch, there might be another manufacturer who can provide a slightly larger pitch to control rpm.
Good Luck, Twinman"
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Question 133: "Thought i would get some expert advice about G&L P-38. Could you advise what the control throws should be for the first flight? Also using OS1.08 engines with master airscrew 14 x 7 3 blades. Have you found the best combination on props two blade versus three blades on a P38? Thanks"
Twinman: "Hi Tony, I am running the master 13x8 three blades on ST 90's on the VQ P-38 and the prototype VQ P-61 and they flew well and looked great. The 108 is more powerful and so I do not see why it would not work fine with the 14x7's. Good Luck, Twinman"
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Question 134: " Hello, Twinman. I have a P-38, it is 86" in wingspan and I have 2 Saito 65s on it, the plane I believe is not heavy at about 13.5 pounds ready to fly (tanks empty) and should fly ok after fixing all of the incidence problems. Anyway my problem is interference, first it is only when I run the engines there is never any without them running, I have been looking at it being the Mc Daniels on board Glow Driver but not totally sure. After changing many things and moving things around with no luck I finally unhooked the glow driver unit completely from the y-harness going the throttle part of the receiver and started the engines, it ran fine for quite some time without an interference while I adjusted the fuel mixture settings and letting the new engines break in, then once while moving from one side of the plane to another my transmitters antenna went parallel with the wing tubes and close to the plane (almost touching it) and the interference started up again, it quit altogether when I first got it away from the plane, after that I have gotten intermittent interference fairly regularly. Some plane information. I had heard that this plane can get heavy so I did everything I could to make it lighter. Now I have a lighter plane, that I don't intend on racing or doing anything fancy with just fly it fairly scale. To help make it lighter I researched a lot of servos and I ended up using GWS Park HPX servos (63oz torque and very fast, also only .6oz each saving approximately 1 oz on each servo) I used these throughout the plane except for the throttle where I used Mini servos mounted of the firewall. The owner said the flaps only needed 25oz torque each and standard servos everywhere else, I went ahead and doubled the elevator servos, the plane only called for 1 with pull-pull wires hanging in the air, but I could not stand that idea, thus giving it 126oz of torque. I have a Futaba 8uaf radio with a Hitec 8ch receiver. I used all brand new equipment. Receiver, battery servos, wire, switch and Y harness. Do you have any suggestions? I did not twist every wire but most are twisted, I don't like the fact that all of the wires run through one tube from the main fuse to the center on both sides to get to the receiver and glow driver but I know this plane flies and severa people have it. Please lend me your experience. Thank you for reading this. Mike"
Twinman: "Hi Mike, I also fly the Futaba, and have been told that there is a board in the reciever that can come loose. If you have one of those magnetic engraving tools that vibrate to cut a marking. Put a pencil eraser on the needle, turn on the radio and touch the reciever with the vibrating eraser. If the board is loose inside the reciever the trouble will restart. This tip came from KMR , the radio repair guy in Ohio who used to be associated with Kraft radios and now repairs them. I am really not comfortable with the glow driver wire running along the
servo wires. Hope this helps. Good Luck, Twinman"
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Question 135: " Twinman, I have enjoyed your comments about multi-engine airplanes and your experience has saved me much grief and even more cash. Thanks for your commitment to the hobby. I am nearing completion of a VQ P-38 and I am taking your advice about a rudder gyro (insurance!). I fly with a Futaba 9CAP, and I'm wondering which Futaba Gyro you would recommend? Or should I use a Hobbico Gyro. Also, should I run separate channels or use a Y connector? Any help is much appreciated! "
Twinman: "Hi Keith, The applicable Futaba for only the rudder is GYA350. The advantage of it over the Hobbico Multipurpose is that you can adjust in the air. The Hobbico is only adjustable on the ground. Now Hobbico have the Aero Gyro for dual inputs such as Ailerons and that one does have in the air adjustability. You can down load the instructions from the Futaba website for review, if you decide to go Futaba.
Either way, I would suggest at least 50% gain as a start. If the tail "Wags" on either, slow down and the wag will stop and readjust down sensitivity slightly.
NEVER TURN THE GYRO OFF!!!!!. You never know when you need it.
If you wish to get the feel of the gyros, put it in a really bad ground looper, such as a Mustang or Cub. Problem OVER ...NOW,,, Just remember to always fly coordinated with the ailerons or the gyro could slightly fight you. Other wise the gyro is invisible.
One small point that will only add to your costs, or insurance as you wish to consider. I use two gyros on my P-38's. The second is on the ailerons. The problem with the P-38 is that the rudders are too small to actually hold well an engine out. Yes, there are reports of guys doing it, but it is really the exception NOT THE RULE. Using both delays the snap roll of death to a point that you can react.
My two cents.
Good Luck and let me know if you have any questions.
PS. I do not wish you preach, but reliability is much more important than a gyro. MAKE SURE THE ENGINES are reliable. Do the vertical test with an assistant every flight."
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Question 136: "Hello George: I came across your site and enjoyed reading all your advice and experiences on twin engined warbirds. Ive been nursing a project of building a Westland Whirlwind for over six years now, but Ive wanted to do it with the new breed of brushless electric motors. I actually have plans all drawn up and gotten as far as building the empennage, but have been procrastinating mainly because of the batteries. It seems though, that with the new LIPO batteries the project is more viable, putting the wing loading between 28-33 0z/ sq. ft., and wanted to see what you think. Since the beginning I wanted to go the electric way, because of motor reliability. My design spans 96 inches, has approx. 1200 sq. in. of wing area and is targeted to weigh between 15 and 17 lbs. Id be glad to send you a set of plans in case youre interested. It should fly well with a couple of .90 two strokes, but Im terrified of all the things that could go wrong with IC engines as you describe in your articles, so I think electric is safer, specially now that batteries have gotten lighter (although very expensive). What do you think? Regards, Javier"
Twinman: "Hi Javier, The reliability is the greatest possible. I am really not the electric specialist, but suggest you go to our sister website at Rcuniverse.com There is a forum ( Glow to Electric Conversions ) that has experts that are doing exactly what you are proposing. Here is one story for a VQ P-38 from that site.
Good Luck and keep us posted. Twinman"
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Question 137: "Twinman, great site and fantastic advice, but I am sorry you haven't put me off moving on to a twin model.
I am a UK flier building a PBY Catalina with retractable undercarriage (a big challenge in itself so any advice on that aspect would be much appreciated). I want to follow your advice and bash a trainer type plain together to gain some experience before risking my pride and joy (when it is eventually built). Would you send me some details please about how to bash a plane into a twin. Many thanks Marc Wade"
Twinman: "Hi Marc, Howdy from Texas to our British Cousin. Here is the text of one of my posts on this subject and I hope it helps.
Subject: Kit Bashing into a twin
There are very few multi engine arf's and few kits,compared to the single engine types for the modeler to choose from. If you want to get multi
experience before the bank is broken on that multi engine war bird, consider "bashing an ARF" to a twin.Yes, the Hobbico Twinstar is good, and an excellent flyer, but small compared to the larger war birds.. One way is to find a long fuselage single such as .60 size ugly stick, put
nose cone over the center engine mount and add nacelles to the wings. Warning, the wing loading sky rockets!! Forties will not fly this well. Go to two .60's, add 8" to the wing and add wing plates on the end. The result flies well and was the subject used for my experiments with various ideas with twins.
Got an Ultra Sport 1000? Need a twin? Create the US 1002. Put an eleven inch tapered nose cone over the original engine mount area. ( Remove the original engine first....Let's not go crazy!!) I added wing plates to the end of the wings that extend 3/4" outside of the airfoil. This is necessary to compensate for the additional weight of the two engines. Make nacelles of 3/16" balsa with 1/16" ply reinforcement inside the vertical walls. Use Grappner 14 oz. square fuel tanks. The recommended engines are healthy Super Tigre .90's with ASP 108 Carburetors
and Master 14x6 propellers. Enlarge the rudder to roughly two times the original size and go to pull-pull on the rudder control. Enlarge the
ailerons to two inches and full length. I added carbon fiber cloth for Dale Brown to the top and bottom of the wing to reinforce the wing structure. It will be necessary to increase the servo power to at least 100 oz or go to two standard servos per aileron. The plane can go so fast in a dive, aileron flutter will result!!! Yes, you will do it!!
This plane will go straight up and flat spin like you would not believe, as well as knife edge all day.
Another way is to create a "100 foot stand off-scale" F-82 twin mustang. Yes, World models makes a F-82 arf, but is still smaller than 80" and light weight.
One plane that works well is to take two Long John 40's, combine the wing to 82", two fuses side by side, I set my engine spacing at 12.5" to use 12x4 props, and a single horizontal stabilizer. You must make a brace to hold the fuse's inline for transport, to take the place of the wing and support the two fuselages. I learned the knife edge circle with that one and still fly it today with two .45's. Instant "Twin John". Still another is to use two Ugly stick .60's and build as with two fuselages,as the Twin Long John. Take the arf's wing halves and glue as normal, then shorten the center joint four rib spaces for only one new joint.This yields around 86" wing span. I recommend adding carbon fiber
strips to the top and bottom of this wing to reinforce against the new found power and maneuverability. Two .60 two strokes fly it well and
two .90's are awesome!!!! (More power ARGG ARGG!!) Pin the firewall with epoxy and tooth picks to stand the added forces. Sheet the center section joint, and glass for additional strength.The horizontal stabilizer is formed using the original stabilizers shortened in
the middle. With this type of two fuselage system,you can either put the receiver on one side and battery on the other, or can practice the concept of two receivers for redundant control. Again, must build brace for transportation to hold the fuselage's in alignment and not break the horizontal stab.
To keep the model interesting I inverted the fuselages to make a low wing model. One problem with this modification was that with such a large wing, so close to the ground, "ground effect" really comes into play on take-off and landing. I added one more "Small Modification". I had extra elevator material left over, so I used it on the wing between the fuselages as a kind of extra flap for more lift during maneuvers. This "Flap" is mixed into the elevator for more response. This plane is fantastic as far as aerobatics are concerned. The more you mix the engines to rudders, the more fun. The two fuselage conversions should keep the props almost touching for better engine out characteristics..My twin Ugly stick is not close.The center line of the engines is 20" for more practice similar to a P-38 with
wide engine spacing. Engine out is good due to the long fuse and larger rudder.
Whatever you do have fun with it, but practice before the first twin war bird on a cheaper alternative. Been there done that..don't do that!!! Twinman"
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Question 138: "Sir, this is my first twin (Vq P-38). I have been reading the reviews and decided to go with this airplane. Was wondering also talking to mike, is O.S. 70's enough for this plane? Currnetly deployed but the project will be waiting when I return. Peter D."
Twinman: "Hi Peter, I have seen this plane fly very well on two ST 60 two strokes and three blade propellors, so I would feel safe with your proposal on two blade props. If you decide to do a loop, which the 60 two strokes will do, try it high!!
Would consider YS 20% fuel to be safe. "Deployed" in this crazy world sounds dangerous. Be careful and come back to "Twin Sanity" in one piece.
Good luck, Twinman"
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Question 139: "Hello Twinman, thanks for a superb homepage with a lot inspiring pictures. I am looking for a P-38 kit wingspan at least 100, but can not really find anything here in Europe, or I look at the wrong places. However I will be in Washington in May and maybe there is a good shop were I could pick up such a kit. I'd appreciate if you could advise nay shop in Washington or eventually Europe. Thanks in advance Ben"
Twinman: "Hi Ben, Here is the comlete list of all P-38's I know of. It is from an earlier post, so I personally have not checked all these addresses latey.
P-38 lover?......my kind of guy!!!! You want composite type kit? Besides above, the only other ones that fit that bill that I know of are Robart at http://www.robart.com and Yellow aircraft at http://www.yellowaircraft.com/prop/index.htm. For built up kits that you can build or customize, here are two more. G&L Hobbies at http://www.glhobbies.com or get the VQ as a non covered version at http://www.vqmodelaircraft.com/ There is another kit at G&P Sales at http://www.rcairplane.net/ Aero Tech in the UK makes a "Quick Build" with much plastic at http://www.aerotechmodels.com/American Eagle at http://www.flyrcmodels.com/ I would also suggest that you go to the associated site for RCU at www.rcwarbirds.com There is a whole section on just the P-38 's. Good Luck, Twinman"
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Question 140: "Hello George, I've recently converted my Super Sportster into a twin. I've been trying to find your article on "Mapping" the throttle channels. I just purchased a Futaba 7CAP as my old Airtronics RD6000 would not allow me to mix the throttles on two channels and still have flapperons. I'm also a little concerned that I may not have enough power with the two Magnum .30s. What do you think?"
Twinman: "John, Mapping is simply putting the second engine on to a separate channel that you can use exponential settings like on a helicopter. Run up the "Master" engine and using exponential, set the second engine speed to match the first. Good job and good luck, Twinman"
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Question 141: "Sir, Serving right now but waiting to get home where myVQ p-38 is waiting to be built. Wondering engine size?? OS 70's II, or 91's, want to run the three bladed prop also. Was wondering if the cowling size is good for these along with the weight of the plane. Don't want to cut to much of the cowling away. Thank you!"
Twinman: "Sir, I have seen the VQ fly with 60 size two strokes, three blade propellers, and flies very well. Mine has ST 90's an is a rocket......Ok, a bit much. Aim for similar power to the 60 two stroke and you will be fine. My vote is the 90 size for extra performance, particularly if flying off of grass.
The centerline of the propeller is four inches from the bottom of the cowls, so you can measure your engine choice. I assume we are talking about inverted mounting. Could I suggest on board glow drivers for safety? You will end up adding some weight to the nose anyway on almost any P-38 I have been around, so the weight is really not an issue.
Thank you for your sacrifice in serving our country. Be careful and come home to a lot of flight time.
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Question 142: "Well, Twinman heres the deal. I have a Hobbico Twinstar and I have decide to put on some retracts and some nav lights....The issue I am having is well for one weight. I want to get the plane down to 6.5 pounds RTF but right now its coming in at 7 pounds. I know that the lighter I can get this bad boy the better performance I will get out of it and also the thought of the wings coming off because of a too high of a wing loading kinda scares me a little. The questions I have for you are, one the retracts seem to be giving me a bit of a problem being that this is the first time I have attempted putting retracts on a plane before. Not only are they posing a problem but the wheel wells themselves are also giving me a headache. If you have any suggestions on how to solve this problem I will greatly appreciate. The second problem I have is the weight. I really want this plane to be at least 6.5 pounds. I kinda went overboard on the reinforcement when it came to the landing gear mounts and the dual aileron mounts I made for the wings. I have decide to use ply for the gear mounts and a thin piece of ply for the aileron mount which will be mounted to the ribs. Also I cant figure out a way to install the retract servo in the wing. I am thinking about cutting out a small part and doing a mod of some soft. I have a 60 size Spitfire that I am looking at as a model for this project and well any help would give me a boast. I have untill the end of the year to finish but the soonner I can finish the sooner I can go test flying it. Thank you for your time and again I appreciate your help on these issues Phil"
Twinman: "Hi Phil, While I currently do not own a Twinstar, I have in the past and am currently flying the Cedar Hobbies twin stick for fun.
BE VERY careful in reducing weight to not reduce structural integrity. With high powered engines, I have seen the wing break and tail break. You did not say what engines you are running. From your discussion, I assume we are talking about mechanical retracts. I am not sure, from you letter, what size wheels you are considering and it sounds like you are going with a tail dragger set up. This is much more difficult with a multi-enigne plane due to uneven engine spool up, but perhaps consider to enlarge the rudder to compensate. One other idea to reduce the size of the wheel wells, is to go to retracts that fold outward for retraction, similar to your Spitfire or rotate sideways for rearward retraction.
I am not sure as to what the problem with your wheel wells are. DO NOT CUT THE MAIN SPAR OF THE WING!!!
I would also suggest that we consult our landing gear expert for further details, if you could previde a bit more information as to what you have in mind.
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Question 143: "Hello George. I just ordered the VQ A-26 and was thinking about using OS 40SX's or Tower 46's. My question is will these engines be enough to spin a 3-blade prop for this plane? Also, I read your section on engine-out emergencies. Will a 3 bladed prop cause greater yaw than a 2-blade and just present more of a problem bringing the plane in for a landing? Thanks for any advise. Later, Mike"
Twinman: "Hi Mike, The OS 40 is similar to the FX and good power. Would consider 15% fuel though. Use master's recommendations and there should be no problem. I am using Master 9x7's with good results on Magnum 32's. The three blade props are slightly less efficient than two blades and so the yaw would be slower in engine out, but try not to find out. Again, always do the vertical test, with a helper, before EVERY flight.
At the risk of getting on a soap box, try to get as much speed on the ground before lift off for safety.
You will like this set up. Have fun and send pictures.
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Question 144: "Hi George, how are you? Got a question for you. I know a while back, you were toying with running multiple engines from one tank. Well, low and behold, I am ina quandry, and want to check on your research. I am building a 136 inch Avro Lancaster. The plane was designed for glow engines, but I have managed to get G-23's in it. However, I have a problem. Beacuase the gear reside in the inner engine nacelles, there is no room for an adequate size tank for the inboard engines. So, I was going to look at installing a 24 ounce tank in the bomb bay, and tie it to both inboard engines. It looks like I would have about 2 feet of line running from the tank to each G-23 carb. Do you think this would work based on your research? I suppose I could also go with 2 individual tanks in the bomb bay. I would like your thoughts. Thx, Jeff Quesenberry"
Twinman: "Hi Jeff, My two cents is RUN IT!! the problems I ran into involved glow engines that do not have fuel pumps. The G-23's, and most gas engines, have fuel pumps, so there should be no problem with fuel draw. You might want to check for sure on a bench and use the largest fuel line you can. Note, you MUST use separate fuel pick up's for each engine in the same tank, or you will get bubbles. Yes, I know the carb;s have check valves, but do not trust them. You also need a separte clunk to defuel the tank and a vent line,,,,,,that is not connected to the MUFFLER....(Sorry to add that, but there are too many lawyers in this world!) Sound neat and keep us posted. Twinman"
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