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Mar 12, 2005, 12:17 AM
Registered User

Scratchbuilt DLG Mk 5 - update

You might have seen my previous threads on the Bluecor/pink foam DLG. I've built 4 previous iterations (reusing some of the components, like the carbon tube fuselage, etc). Finally, Mk 5 is finished after about a month of on and off work (I was out of town for approx. 1.5 weeks in the middle). Still, there's more work in this version than any of the previous models. Hopefully, it'll pay off with superior performance. Here's a breakdown of the design improvements/changes:

Mk 1: undercambered Bluecor wings, full length carbon tube, pink foam pod (3.9 oz)
Mk 2: aerodynamically shaped Bluecor pod, lower aspect ratio Bluecor wing with approx. 25% more surface area (3.7 oz)
Mk 3: Reinforced Bluecor pod; built as a repair to Mk 2 (4 oz)
Mk 4: wing replaced with flat bottom pink foam roughly based on the AG-series airfoils (32" WS). Bluecor pod. (3.9 oz)
Mk 5: fiberglassed pink foam wing based on this Japanese model, which in turn roughly resembles the SuperGee II:

I think I built the wingspan to 32", but I forget the exact number. This should hopefully provide the best performance of my models so far, since it has a proven airfoil, reasonably light weight (3.85 oz AUW) and a decent wingloading (approx 3.5 oz/sq ft, which was my target). The strength of the airframe is extremely high, even with just a single layer of .73 oz FG on top of the wing and a small piece doubled at the center joint. I used Polycrilic for all FG work. The bottom of the pod is also covered with a single layer of .73 oz FG, and there are small patches to reinforce the tail feather joints.

Radio gear is a GWS R4P-N II with one HS55 and one Pico Std. I think 2 Picos would be a better match since the 8.5 oz HS55 is overkill for this application. My battery is a 2s 340mAh lipoly - if I trusted a single cell, I could probably use that and save 14-15 g, since I am using a 5g Jeti ESC for its BEC. I think the response is better with the 2 cell pack, even though it means another 15 g of weight - I needed it to balance anyway. I built the nose from a chunk of EPP foam, which should give some "bounce". The pod is a box construction of Bluecor. Pushrods are 1/25" music wire supported every few inches with small heatshrink tubing.

I'll give it a maiden tomorrow morning, hopefully at my normal field if it isn't too windy. Pictures coming soon.
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Mar 12, 2005, 10:59 AM
Originally Posted by stjobs
.....with one HS55 and one Pico Std. I think 2 Picos would be a better match since the 8.5 oz HS55 is overkill for this application.....
That would be ~8.5 grams not ounces.
Mar 12, 2005, 11:00 AM
I'm really interested in your design. Do you have pictures or drawings of MK5?
Mar 12, 2005, 12:04 PM
Registered User
"That would be ~8.5 grams not ounces."

My fault. I was posting late at night.
Mar 12, 2005, 06:01 PM
Registered User
"I'm really interested in your design. Do you have pictures or drawings of MK5?"

I'll get some pictures as soon as possible - probably tonight or tomorrow afternoon. I can tell you that the wing is identical to the Chibi SAL 3 on the Japanese site, except I enlarged the wingspan somewhat. The tail feathers are my own design, as is the pod.
Mar 13, 2005, 08:47 PM
Registered User
Good flights today. The wind finally calmed down, and although there were regular 5-7 mph gusts, the DLG flew very nicely. In calm conditions, the glide slope is very flat and it's surprisingly fast. The launch height is much better than my previous models, also. Even a light SAL yields approx. 70 feet, and with a hard discus launch I was estimating 100+ feet. I'm looking forward to more flights in calm conditions. It seems fairly sensitive to wind, either by being pushed to the side or weathervaning. If it's flying into the wind, the penetration is poor and it just sinks to the ground.
Mar 14, 2005, 11:18 AM
Excellent! Glad to read that you had a good maiden.

Mar 14, 2005, 03:11 PM
Womb Drifter
Phiber Optik's Avatar
Very interested in your design as well. Please post some pics soon! (I need some ideas!)

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