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Old 11-19-2015, 05:12 PM   #11
Struts1
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Re: Thinking about getting a Sapac Grippen


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Let's say if inner walls of aft fuselage where EDF unit will be installed get more thin when foam will be removed to make space for 90mm unit, I can at that time glue very thin yet super strong and light weight fiberglass skin panels on the outer walls with epoxy to reinforce it and then prime and paint the whole section.
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Old 11-20-2015, 08:17 AM   #12
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Re: Thinking about getting a Sapac Grippen

Sam, never did anything with that plane I got from you. Sent it on to another hobbyist.
I have been largely inactive in the hobby for a few years due to a number of factors. I spent a pile of dough on turbines trying to stir my interest and found that I was just not willing to put in the travel time to events etc. I just had so much fun with that foam Sabre I can't help but think I should have another. I only ever had a HET fan in it and now with the better fans, giving a more pleasing sound, the concept is even more viable. Eric has become an acknowledged expert and shares his R & D findings freely. I would certainly take his advice.
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Old 11-20-2015, 08:21 AM   #13
Bob Byrnes
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Re: Thinking about getting a Sapac Grippen

Myself and my friend (another Eric) had those Grippens years ago when we started fooling around in EDF. I remember at the time there were threads on one of the sites (RC Groups?) that detailed the conversion to a 90mm set up. Maybe an archive search will help. I recall that the heavier fan made balance easier since the builder moved it rearward when doing the conversion.
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Old 11-20-2015, 02:24 PM   #14
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Re: Thinking about getting a Sapac Grippen

I am sure these conversations have been done in past with this model. I will try to find old threads on it and see how those guys did it. I have been making giant scale models with foam for many years. Once I get to see what others did I will either use same methods or enhance on their ideas to achieve my goal and end result.
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Old 11-23-2015, 11:36 AM   #15
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Re: Thinking about getting a Sapac Grippen

Quote:
Originally Posted by Bob Byrnes View Post
I remember at the time there were threads on one of the sites (RC Groups?) that detailed the conversion to a 90mm set up. Maybe an archive search will help. I recall that the heavier fan made balance easier since the builder moved it rearward when doing the conversion.
Looks like this is that conversion thread u mentioned...

http://www.rcgroups.com/forums/showt...t=Sapac+Gripen
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Old 11-24-2015, 12:10 PM   #16
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Re: Thinking about getting a Sapac Grippen

After reading rcg thread on this coversion, I have decided to go ahead and install 90mm in the very back section of the Gripen after I get it. It's a matter of sanding and opening up tail end of the foam exhaust outlet section or cutting it off and replacing it with newer hot wired section with bigger inner diameter for better exit thrust flow and 100% FSA. For 90mm EDF exhaust nozzles's outlet should be 72mm.

Proper retracts are still to be figured out mainly for the main landing gears....I think 2x 3s 5000 lipos would be better then single 6s pack for proper cg.
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Old 11-29-2015, 04:35 PM   #17
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Gripen has arrived!, time to build her with modifications on the way...

Earlier today Eurofughter Typhoon went and this Sapac Gripen arrived and have entered in the fleet. Build will commence soon.
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Old 11-30-2015, 05:53 AM   #18
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Re: Sapac Gripen build with modifications....

I have been collecting different types of drawings on Gripen from the Web and I found one very interesting drawing that compares the dimensions at same scale of Rafael, Mirage 2000 and Gripen together from the top. It looks like my Mirage 2000C and this Gripen are same scale or very much close to each other. See what I mean yourself.
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Old 11-30-2015, 06:05 AM   #19
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Re: Sapac Gripen build with modifications....

According to a thread in RCG and by reviewing a past thread on here by Eric aka 4stripes that 80mm and 90mm EDF units can be placed at the very back inside the fuselage by carefully removing foam under the vertical fin. As for exhaust outlet, if 90mm edf is being used then to get proper outlet FSA it should be 72mm in its diameter. To achieve that, I see 2 ways of doing it:

1- By adding more foam on the outer side of the present exhaust nozzle all around it and then sanding it from the inside to get 72mm inner diameter.

2- By cutting off last 4" behind the vertical find and then making another section with inner opening of 72mm and outer diameter of say 77mm. This will involve hot wiring, regluing, reshaping outside to match the curves of all 4 sides.

I have still not decided what route out of 2 I will take to achieve this goal but I'm open to more suggestions regarding this areas modifications.
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Keeping scale scratch building part of the hobby alive.
We'll build new kits or arfs for you and also rebuild your previously crashed models.
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Old 11-30-2015, 06:09 AM   #20
Struts1
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Re: Sapac Gripen build with modifications....

I have decided to paint my model in very special Brazilian livery, I still have to find pictures showing under side on the particular Gripen jet..
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__________________
Keeping scale scratch building part of the hobby alive.
We'll build new kits or arfs for you and also rebuild your previously crashed models.
Radios: Spektrum, Futaba
Engines: Electric, Gas and glow
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