Andrew Cousins Posted June 23, 2016 Author Share Posted June 23, 2016 Guys the hog turned up a week and two days late. Apparently that's next day according to YODEL. Anyway I have been building and I have a question. The instruction say to completely sheet the wings before gluing the two half's together. My question. Would it be better to glue both wing half's together then sheet the wings. Doing it this way would make it easier to see if both wing half's were perfectly flush with each other. before epoxy them together? Just a thought I suppose I could sheet the bottom of the wing half's then join them What do you experts out there think? Cheers Andy Quote Link to comment Share on other sites More sharing options...
Trevor Posted June 23, 2016 Share Posted June 23, 2016 I can't remember what the old plans said, but I only sheeted the leading edge section back to the spar, and of course the central couple of rib bays. The aft section of the rest of the ribs were cap stripped. I think it's a good idea to leave the top sheeting off until the wings are joined. This makes it much easier to ensure that the dihedral brace fits snugly and is well clamped in position while the glue dries. Quote Link to comment Share on other sites More sharing options...
Bob Cotsford Posted June 23, 2016 Share Posted June 23, 2016 I usually sheet the leading edge back to the spar top and bottom before joining the halves. That way the sheet forma a rigid box which will help to stop warps creeping in. The centre section sheeting then goes on after joining the two halves. Quote Link to comment Share on other sites More sharing options...
Andrew Cousins Posted June 23, 2016 Author Share Posted June 23, 2016 Trevor Bob Both good tips and points. I would like to see that the joint between the two wings is perfectly flush so im tempted to leave the sheeting off. But Bob your point is also good do not want any warp in the wings. I suppose if I sheet the top and bottom of the leading edge but leave to center sheeting off I would still have some visibility of how well I have joined the wings. Saying that I would like to see that the dihedral brace is also glued perfectly in place. What do you guys think if I just put the bottom sheeting on then joined the wings? would this be enough strength to stop any warps creeping in? Quote Link to comment Share on other sites More sharing options...
Trevor Posted June 23, 2016 Share Posted June 23, 2016 If I remember rightly, there's no washout in the Hog wings and the rear part of the underside is pretty flat so it's quite easy to support one wing panel flat on the bench while you apply the top leading edge sheeting. In the end, it's a case of which sequence you feel most comfortable with - either join the wings first and accept you have to take a bit more care with the sheeting or sheet first and accept you have to take a bit more care over fitting the dihedral brace. I often claim that working out the best order to do things, and working out how to hold things together while the glue dries, are the two most important things to master in the craft of traditional building! Quote Link to comment Share on other sites More sharing options...
Andrew Cousins Posted June 24, 2016 Author Share Posted June 24, 2016 Trevor good points will have a think and a run through and then make my mind up before I start gluing. Another thing, I have altered the dihedral of the wing. looking at the instruction book it looks quite excessive. I have read a number of threads and they have reduced it. My sig kit calls for 6 deg of dihedral so right or wrong I modified the template in the manual to give me 4deg instead of 6deg so that's 8deg over all. I now need to make a new dihedral brace. I think I have it right in my head but I just want to double check. With the new brace I need to have 4deg from the horizontal both top and bottom of the brace. I would measure it but I don't have it to hand (just thought of the brace while typing this) This would give me a less pronounced V shape to the brace than if I had 6deg from the horizontal. am I correct? TA Andy Quote Link to comment Share on other sites More sharing options...
Trevor Posted June 24, 2016 Share Posted June 24, 2016 I can't remember the figures and it really isn't critical. I think I roughly halved the dihedral on Fred Dunn's original plan. Quote Link to comment Share on other sites More sharing options...
Andrew Cousins Posted June 27, 2016 Author Share Posted June 27, 2016 Many Thanks Trevor I am looking at a total dihedral of 8deg. Its going to be a case of suck it and see. Quote Link to comment Share on other sites More sharing options...
John Payne Posted June 27, 2016 Share Posted June 27, 2016 Hi Andrew, just seen this thread. I have flown my Astro Hog with an ASP 52 four stroke (underpowered for the windier weather and the one in my picture) a Thunder Tiger 91 four stroke (comfortably overpowered!) and an ASP 65 four stroke which was fine for my style of aerobatic fun. I also built it from the original plan with inset ailerons and lots of dihedral. To say the rudder had authority is an understatement. I cut the wing in half and reduced the dihedral to 1 inch under each tip and it now flies a lot better. It is not unstable without the excess dihedral (needed when it was first designed), it flies nice and smooth and it performs nice aerobatics. Hope this helps. Quote Link to comment Share on other sites More sharing options...
Andrew Cousins Posted June 27, 2016 Author Share Posted June 27, 2016 John Many thanks for the heads up with the dihedral. its good to hear from some one that has made this modification. I am looking forward to finishing it and flying now as well. will not be so concerned now about removing some of the dihedral. Andy C Quote Link to comment Share on other sites More sharing options...
Andrew Cousins Posted July 4, 2016 Author Share Posted July 4, 2016 Help Guys I have just about finished building the wing on my hog. Unrolled the plan for the fuzz and noticed that the plan calls for 0 degrees down and side thrust. Now all the other plans I have built from require down and side thrust. Is this right with the SIG astro hog build. Can any of you Hog builders out there help me out please. Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 4, 2016 Share Posted July 4, 2016 Seems a touch unusual i must admit. But even if its right i would mount the engine on a glass/nylon engine mount (the T type) and then if you find you need some tweaks you can easily shim the mount to give the required change. i believe the hog has the engine mounted on hardwood rails? if so i would recommend you change that as its not really very secure as the wood will compress over time and the engine will keep coming loose. Quote Link to comment Share on other sites More sharing options...
Andrew Cousins Posted July 4, 2016 Author Share Posted July 4, 2016 Thanks Jon The Sig kit I have has the T type glass/nylon engine mount as you mention. I have not mounted it yet just started looking at the fuzz plans. Yes I thought of shimming the engine mount if needed just found it very strange to not have any offset for the engine. What kind of reaction will I see on the maiden flight if I follow the plan and have no offset but then find I need it (if you know what I mean)? Quote Link to comment Share on other sites More sharing options...
Martyn K Posted July 4, 2016 Share Posted July 4, 2016 I built mine 5 years ago from the original 1959 plan The build blog is here **LINK** It was a great flyer. Mine crashed after a Rx power failure. I still miss it.. I also reduced the dihedral as well. - down to about 1.5" under each tip IIRC. Don't take it all away, the fuselage is quite deep and the engine (thrust line) mounted quite high in relation to the wing position. I eventually used as SC61 as the power plant Good luck Martyn Quote Link to comment Share on other sites More sharing options...
Braddock, VC Posted July 4, 2016 Share Posted July 4, 2016 Sig have an excellent reputation and my recommendation is to follow the instructions. If you find that you've overpowered the model with your laser 80 (and you almost certainly will) it's relatively straightforward to adjust the thrust line with either wedges or washers. FWIW the instructions for my Flair astro hog show an irvine 40 2 stroke and 4 degrees of right thrust. The engine on the flair version is bolted to a plate which, in turn, is epoxied to engine bearers that form part of the airframe thus slightly more difficult to adjust once built. The model is virtually identical except for the tailplane position, ailerons and the u/c. Size and weight are the same. The only other difference I can spot is the c of g on the flair version is 4 inches back from the leading edge of the wing. If you want a lot more info or twaddle (depending on your view) rcg and rcu worth a look. Quote Link to comment Share on other sites More sharing options...
Trevor Posted July 4, 2016 Share Posted July 4, 2016 Andrew, My hog is set at zero-zero and flies fine. With models like this, I can't see why you would need downthrust. At the risk of taking this discussion off topic, I would venture to say that many models which 'need' downthrust are actually using it to overcome a tendency to zoom up under power, a behaviour which has often been exacerbated by a misguided attempt to tame the zoom by adding more lead in the nose! When asked to sort out such ill-behaved models, my first step is to remove both the lead and the downthrust. Once the cg is back where it should be, little if any downthrust is needed. Side thrust is a different matter but, unless you are an aerobatic purist, I suspect that you will not notice any issues with a straight thrust line in the Hog. That said, my experience is with a lighter than usual, electric powered version and my flying style isn't particularly aggressive on the throttle so you might do better to look elsewhere for guidance on this one. Either way, having the scope to shim the mount a degree or two is useful if you want to do a bit of fine tuning. Time for a few pictures of your progress? Quote Link to comment Share on other sites More sharing options...
Andrew Cousins Posted July 4, 2016 Author Share Posted July 4, 2016 Hi Martyn K I have had a look at your Blog how much side thrust did you put in. I am building from the SIG kit so not sure if they have compensated for this in the fuzz sides. not measured them yet. I know sig have made quite a few changes from the original plan but I'm not sure if down, side trust is one of them. Quote Link to comment Share on other sites More sharing options...
Martyn K Posted July 4, 2016 Share Posted July 4, 2016 According to my blog I built in 4 degrees of Right Thrust There was some packing to the Left hand side of the mount as you can see If you reduce the dihedral, you will need less downthrust as the drag component will be moved down, I don't think I had any downthrust on mine. However, remember that the wing section is a semi symmetrical profile and the model will zoom when pulling up from a fast dive. The lift component will be higher at speed and this has nothing to do with downthrust. Martyn Quote Link to comment Share on other sites More sharing options...
Andrew Cousins Posted July 4, 2016 Author Share Posted July 4, 2016 Guys many thanks for the advice it is all very much appreciated. Its good to hear that there are hogs out flying set to zero zero thrust. Its also good to know SIG have a good reputation And as the kit has the T type engine mount if I need to add a bit of side or down I will be able to shim the mount. Photos well the wing is already built but as I have said im just about to start the Fuzz so I will have to brush up on my photography skills and get some pictures of the fuzz build. I'm planning on fitting my brand new shiny laser 80 inverted so will cover the top of the fuzz engine bay rather than the bottom as per the instructions. Also its going to be a tail dragger as well. Once again thanks guys I'm sure I may have one or two more questions. Could be a few about getting photos on here!!!! Cheers Quote Link to comment Share on other sites More sharing options...
Andrew Cousins Posted July 4, 2016 Author Share Posted July 4, 2016 Guys many thanks for the advice it is all very much appreciated. Its good to hear that there are hogs out flying set to zero zero thrust. Its also good to know SIG have a good reputation And as the kit has the T type engine mount if I need to add a bit of side or down I will be able to shim the mount. Photos well the wing is already built but as I have said im just about to start the Fuzz so I will have to brush up on my photography skills and get some pictures of the fuzz build. I'm planning on fitting my brand new shiny laser 80 inverted so will cover the top of the fuzz engine bay rather than the bottom as per the instructions. Also its going to be a tail dragger as well. Once again thanks guys I'm sure I may have one or two more questions. Could be a few about getting photos on here!!!! Cheers Quote Link to comment Share on other sites More sharing options...
Martyn K Posted July 4, 2016 Share Posted July 4, 2016 Adding Photos - read This: **LINK** Basically, create an Album, Add/upload Photos - much easier using a PC, this site isn't very mobile friendly unfortunately Back to your topic, new post, click on the camera icon, select the Album and then the photo. When the photo is inserted, click on the last photo inserted, it will turn blue, move the cursor one space right using the right arrow key, press enter and type your message That the way I do it. Others have their own tweaks Quote Link to comment Share on other sites More sharing options...
Andrew Cousins Posted July 4, 2016 Author Share Posted July 4, 2016 Magic thanks Martyn will have a go when I have some photos to put on. Quote Link to comment Share on other sites More sharing options...
Andrew Cousins Posted July 6, 2016 Author Share Posted July 6, 2016 Hi all Just a quick one. I thought I would contact Sig to see what they had to say about the zero zero on the thrust lines. here is what they replied " What is shown on the plans is correct for most pilots. You can add some of each if you feel it needs it after flying it. Good luck," so its crack on with the fuzz build and I hope to have it finished in a few weeks. Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 6, 2016 Share Posted July 6, 2016 Sounds good! I was also thinking about the dihedral question and i seem to recall a 3 channel version. did such a beast ever exist? If so it might explain it Quote Link to comment Share on other sites More sharing options...
Andrew Cousins Posted July 10, 2016 Author Share Posted July 10, 2016 Got a bit of a problem started to build the fuzz and I have a question for Jon H. first off the problem. Right I have marked out the thrust lines on the fire wall. I have offered up the engine mount to the fire wall to get the engine positioned with the trust line down the center of the crank. PROBLEM when I put the engine (laser 80) on the mount I have to have it right at the very end of the engine mount. so much so that the end of the engine's mount is flush with the end of the plastic engine mount itself. even with the engine this far forward the carb just touches the fire wall. questions 1. is it safe to mount the engine this far forward on the plastic mount 2. how much clearance does the carb need so it is not air restricted. Thanks All Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.