Ben-Erik Ness Posted November 11, 2018 Share Posted November 11, 2018 I have had this idea on building a PSS Dash-7 for a while, and now I have started. I must say that John Hill's DHC-8 a good sourc of inspiration! **LINK** The project in brief: It will be constructed from white foam that is going to be sheeted with balsa or abachii (yet to be decided) I have not calculated the scale of the plane but it's slightly under 1:10 with a wingspan of 238 cm. The fuselage is made circular, so this is not to scale, but it makes it easier to make sections of the fuselage. the nose section is first cut by hot wire vertical and horizontal, then carved to shape with a sharp knife! The aft fuselage is made by hand, with a knife! I'll upload a couple of pictures soon, so more to come! Ben-Erik Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted November 11, 2018 Author Share Posted November 11, 2018 A few pictures... This is my inspiration, having flown with Wideøe in the 80's and Petrolium Oil Services less than 10 years ago. Hoping to acheive slow and floating flying capabilities in low to medium lift... Icut the circular sections by rotating the square into a circle, I have a needel in the center that the foam block is placed on to. It's not a small plane!! Quote Link to comment Share on other sites More sharing options...
Tony Bennett Posted November 11, 2018 Share Posted November 11, 2018 i like that sir. not enough airliners moddeled. Tony B Quote Link to comment Share on other sites More sharing options...
Former Member Posted November 11, 2018 Share Posted November 11, 2018 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted November 18, 2018 Author Share Posted November 18, 2018 Working on the wing saddle. Getting the shapes right from the wing saddle to the forward foselage is kind of difficult... Not getting it right unfortunately. I guess I have to make a new section just in friont of the wing This is what it should have looked like... Note to self. Have a better look at pictures before carving foam next time... Edited By Ben-Erik Ness on 18/11/2018 20:55:04 Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted November 24, 2018 Author Share Posted November 24, 2018 I have now cut two new sections and reshaped the wing saddle. It's complex shapes, and it's far from scale, but it looks better than the last attemt. Isolated without any pictureas reference I think itlooks much better now. I have to remind myself that this is not a scale competition... Last night I also god a huge chunk of balsa sheets on Black friday sale... This is how it looks right now: Edited By Ben-Erik Ness on 24/11/2018 11:02:59 Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted December 30, 2018 Author Share Posted December 30, 2018 A little free time in the holidays to work on the Dash-7. As I have stated earlier, I was happy with how the wing was blending into the body. But after some considerations I have done it over again. I have also glued the fuselage together permanently, apart from the nose section. This plane will due to the layout come out tail heavy, so in order to utilize the fact that I will need nose weight I have started to improve strength in nose section. Due to the environment on the places I fly a strong nose will benefit to a longer life of the model. Not rocket science, carbon and epoxy will do the job! Wings next! Happy holidays Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted January 3, 2019 Author Share Posted January 3, 2019 Got some time in my hangar the last two nights... Cutting wings. Haven't done this before, but I'm quite happy with the result She's going to be big... Won't be a fast flyer either... Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted January 4, 2019 Share Posted January 4, 2019 Looking good Ben - I like the nose reinforcement, should go through walls now Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted January 4, 2019 Author Share Posted January 4, 2019 Posted by Andy Meade on 04/01/2019 09:48:14: Looking good Ben - I like the nose reinforcement, should go through walls now Thanks Andy! The nose is rock solid, the rest of the foam nose section will be coverd with glass cloth and epoxy. However, next step will be to cut the fin and the tailplane! Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted January 6, 2019 Author Share Posted January 6, 2019 Need some advise guys! I'm trying to plan ahead of my progression. Now I'm planning the flaps on this monster. My plan is to have full offset flaps from the root to the second nacelle. Then a flap, bottom hinged half of the rest, and the outer rest will be normal ailerons. Then I can combine aileron and the center flaps in the turns and utilize lots of flaps upon landings. I’m now on to the inner main flaps. They are 25% of the distance from Leaning edge to tailing edge. Have a look at the video. Will this work? Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted January 7, 2019 Share Posted January 7, 2019 I can't see why it wouldn't work. People have used the Robart pin hinges offset below the wing in hard balsa fairings in the past to achieve the same result. What's your worry - the mechanism, or the flap effectiveness? Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted January 7, 2019 Author Share Posted January 7, 2019 Posted by Andy Meade on 07/01/2019 09:56:48: I can't see why it wouldn't work. People have used the Robart pin hinges offset below the wing in hard balsa fairings in the past to achieve the same result. What's your worry - the mechanism, or the flap effectiveness? Technically it will work, it's the effect in flight I'm thinking of. I need the same stop effect as I have on my Xplorer... Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted January 8, 2019 Share Posted January 8, 2019 I think it's quite a big slotted flap - generally slotted flaps produce lift more than a plain flap would, as the high pressure air from under the wing can bleed to the top surface and help offset the start of stall. As long as you can get a large angle on the flap, it should work as intended. Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted January 20, 2019 Author Share Posted January 20, 2019 After a busy week with 3 days travelling it's good to be back at the Dash-7. At least one part is getteing close to finished. The horizontal stabelizer is now sheeted with balsa: What concerns me is the weight. This one is 221 grams, maybe not bad for a 80cm wingspan. I realized that the 1,5mm balsa I got had a great variation in weight, and I think I could have built the wing lighter. But this is the first time I'm sheeting foam with balsa, so I might have to be happy with the result after all... Any opinion will be appreciated! Hope to have the wings ready for sheeting by the end of the coming week... Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted February 4, 2019 Share Posted February 4, 2019 221g doesn't seem at all bad, I'd say go with it. If you need to make another in the future, at least it's a wing, right? I know that's not ideal, but that's what I always say to myself! Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted February 7, 2019 Author Share Posted February 7, 2019 Posted by Andy Meade on 04/02/2019 09:17:34: 221g doesn't seem at all bad, I'd say go with it. If you need to make another in the future, at least it's a wing, right? I know that's not ideal, but that's what I always say to myself! I do agree... My main wings with 1mm balsa sheeting came out at 515 geams each (before glassing), so there is no doubt about it's possible to build the elevator lighter. I'll go on with the build and decide later. It only takes a few evenings... Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted February 19, 2019 Author Share Posted February 19, 2019 A litle update. Wings are now sheeted. I'm happy with the result, and I thought I'll show how I did it. The wings are really stiff, and as you will see, carbon does the job! This is the underside. 6 strands of carbon rowing embedded in the foam with epoxy: Then I added the carbon mat along the length of the wing, all with epoxy: The same procedure on the top of the wing, apart from the embedded carbon in the wing: I let the carbon and epoxy cure with the wing under pressure.. The end result: All pieces together, It's going to be big... Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted February 19, 2019 Author Share Posted February 19, 2019 Next task is how to design the tail. How should I attach the horisontal stab on the T-tail. This is my preliminary plan... Any ideas and suggestions out there?? Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted October 26, 2020 Author Share Posted October 26, 2020 My Dash-7 has been on the shelf for some time, but now I'm at her again. I foud one of my own old photos taken after arriving from Oslo, way back in 1983, that got me going! I have done some stregthening of the wing box, in order to distribute load, and right now I'm in the midle of sheeting the fuselage with balsa. I also wanted to strengthen the area where the tail fin is mounted hence the carbon fiber! Hope to show more in the next few days! Quote Link to comment Share on other sites More sharing options...
Phil Cooke Posted October 26, 2020 Share Posted October 26, 2020 Looking great Ben - good to see this back on the bench again!! Keen to see this one on the slopes! Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted October 31, 2020 Author Share Posted October 31, 2020 More progress to report! Fuselage is finally sheeted with balsa. I have never done a balsa sheeted fuselage before, but I'm pretty happy with the result.It's far from perfect, but when it glides past the slope nobody will notice! The main wings are also glassed. I'm using peelply and that makes it easier to acheive a good result! Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted November 3, 2020 Author Share Posted November 3, 2020 I have started on the part of the build that I have dreaded the most, building a functional detacable T-tail section. Due to the size of the fuselage (over 2m long) I need to be able to take the tail and tailplane apart for transport. The idea is to have a 10mm carbon rod/tube that functions as a threaded rod, running inside a 12mm carbon tube in each section, pulling everything together from bottom to top. The most challenging part is to get everything together strong enough, and to mount the whole thing lined up correctly. My laser will help a lot here.. Pictures shows the tail before sheeting the tail and rudder... Quote Link to comment Share on other sites More sharing options...
Ben-Erik Ness Posted November 5, 2020 Author Share Posted November 5, 2020 Posted by Andy Meade on 04/02/2019 09:17:34: 221g doesn't seem at all bad, I'd say go with it. If you need to make another in the future, at least it's a wing, right? I know that's not ideal, but that's what I always say to myself! I have for some time debated with myself if I should rebuild the tailplane. Well, I thought I'd have a go at it. Same construction as last time, less carbon reinforcement and much lighter balsa sheeting. My aim was to cut the weight in half! It took me the evening to process is, and I'm delighted to finsh it at a mere 103 grams, ready for glassing. This means a reduction in noseweight of about 400 grams, and a saving of a total of 500 grams og the AUW - absolutely wort the effort! New wing: Quote Link to comment Share on other sites More sharing options...
Andy Meade Posted November 5, 2020 Share Posted November 5, 2020 Goes to show that you should never listen to me! Great result and progress so far, keep it up 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.