Skymaster F5 questions
10-04-2014, 05:23 PM
#1
Skymaster F5 questions
Well not questions so much I suppose just curiousities. I just picked up a Skymaster f5 after a decade of trying to convince the original owner to make me a deal.
I'll be powering it with another trusty AMT Pegasus, yes air start, still love those engines, that is turned up to 34lbs of thrust.
For those that have been flying these birds, what have you found the optimal CG, throws, etc. Any tips on the jet? Any structural things to modify or keep an eye on? Even though the jet is a decade old it has never flown.
Thanks in advance!
I'll be powering it with another trusty AMT Pegasus, yes air start, still love those engines, that is turned up to 34lbs of thrust.
For those that have been flying these birds, what have you found the optimal CG, throws, etc. Any tips on the jet? Any structural things to modify or keep an eye on? Even though the jet is a decade old it has never flown.
Thanks in advance!
10-04-2014, 06:51 PM
#5
Hi Jeremy,
Definitely a Skymaster, I can't tell you if it was a user induced build issue or a design /materials issue as it wasn't mine. It was only the second flight on it and the pilot was flying it really fast and pulled a lot of g's in a hard turn when the right stab departed. He was flying it like you can fly a Flash so, it may just be that it was over stressed and never intended to be flown like that but, have a look back there to make sure all is well.
Mike
Definitely a Skymaster, I can't tell you if it was a user induced build issue or a design /materials issue as it wasn't mine. It was only the second flight on it and the pilot was flying it really fast and pulled a lot of g's in a hard turn when the right stab departed. He was flying it like you can fly a Flash so, it may just be that it was over stressed and never intended to be flown like that but, have a look back there to make sure all is well.
Mike
Last edited by luv2flyrc; 10-04-2014 at 06:53 PM.
10-05-2014, 04:41 AM
#8
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Hi Jeremy
I just finished my second one , the only mods I made were to box the rear stab assembly , add 1/4 inch spacer to the front retract and add two cross braces to the main formers to strengthen the main assembly
The main landing gear is positioned too far back , it requires a lot of elevator authority for rotation, the spacer increases the AOA and helps with smoother rotation
The best way I have found for a better take off is to apply full up elevator as you apply power , as soon as the nose rotates reduce the amount of elevator with enough practise the take offs are not as steep
This plane increases speed when the nose is pointed down very quickly very little drag. you have an older kit so care must be taken on applying too much elevator at high speed
The plane has very little surface area head on I found mine disappeared when it was pointed straight at at me it was only for a second but it seemed a lot longer
I started with the factory throws and cg I moved the cg back just a little it is very sensitive
Anyway good luck if you need pics I can take some for you
Ted
I just finished my second one , the only mods I made were to box the rear stab assembly , add 1/4 inch spacer to the front retract and add two cross braces to the main formers to strengthen the main assembly
The main landing gear is positioned too far back , it requires a lot of elevator authority for rotation, the spacer increases the AOA and helps with smoother rotation
The best way I have found for a better take off is to apply full up elevator as you apply power , as soon as the nose rotates reduce the amount of elevator with enough practise the take offs are not as steep
This plane increases speed when the nose is pointed down very quickly very little drag. you have an older kit so care must be taken on applying too much elevator at high speed
The plane has very little surface area head on I found mine disappeared when it was pointed straight at at me it was only for a second but it seemed a lot longer
I started with the factory throws and cg I moved the cg back just a little it is very sensitive
Anyway good luck if you need pics I can take some for you
Ted
10-05-2014, 05:21 AM
#9
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Ted,
Approximately, how much runway is covered before your F-5 rotates? I have a FB F-5 which is similar to the Skymaster model. So far only two flight, but each flight covered about 600' of runway before the model jumped off the ground pointing the nose up nearly 90 degrees. Once in the air, the plane is very agile and flies like it's on rails. Just need to find the secret to shorter, smoother take offs. I also increase the aoa by putting a 3/4 spacer under the nose gear.
Approximately, how much runway is covered before your F-5 rotates? I have a FB F-5 which is similar to the Skymaster model. So far only two flight, but each flight covered about 600' of runway before the model jumped off the ground pointing the nose up nearly 90 degrees. Once in the air, the plane is very agile and flies like it's on rails. Just need to find the secret to shorter, smoother take offs. I also increase the aoa by putting a 3/4 spacer under the nose gear.
Last edited by David Jackson; 10-05-2014 at 05:24 AM.
10-05-2014, 05:37 AM
#10
Hi Jeremy,
I loved my Skymaster F-5. It flew like a sport jet, and slowed way down for landings. I had a P-160 in mine, and needed all of that, in my opinion. Unfortunately, it came apart in the air, due to no glue on the bulkheads that have the wing spar receivers on them. Those bulkheads are an integral part of the spar system. They come from the factory covered with carbon, epoxied on for extra strength, so there is no way to see if there's sufficient glue on the joint. Please flex your wings, as if you were pulling g on the airplane, and look at the bulkheads with the spar recievers on them, to make sure they are strong, and properly secured.
In all fairness, I flew mine aggressively, and skymaster replaced the airframe, when I sent them pics of the faulty glue joint. You will love the way it flies, and it has a great presence in the air. Good luck bud.
Erik
I loved my Skymaster F-5. It flew like a sport jet, and slowed way down for landings. I had a P-160 in mine, and needed all of that, in my opinion. Unfortunately, it came apart in the air, due to no glue on the bulkheads that have the wing spar receivers on them. Those bulkheads are an integral part of the spar system. They come from the factory covered with carbon, epoxied on for extra strength, so there is no way to see if there's sufficient glue on the joint. Please flex your wings, as if you were pulling g on the airplane, and look at the bulkheads with the spar recievers on them, to make sure they are strong, and properly secured.
In all fairness, I flew mine aggressively, and skymaster replaced the airframe, when I sent them pics of the faulty glue joint. You will love the way it flies, and it has a great presence in the air. Good luck bud.
Erik
10-05-2014, 06:44 AM
#11
Ted, if you could take a picture of what you did to the stab assembly and a picture of how you braced the spar formers I would greatly appreciate that. What did you power yours with? I figured it would lose visual pretty easy from the front, my raptor and firebird are the same. Not much to see when it's head on with the really thin wings.
10-05-2014, 09:03 AM
#13
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The Wingham crash was a Skymaster T-38. Whether the construction of the stab is similar between F-5 and T-38, I don't know. The pilot who was flying it is a yank and banker and flies real hard.
Last edited by Jeremy300; 10-05-2014 at 09:05 AM. Reason: spelling
10-05-2014, 10:02 AM
#15
Valid comment and concern still, I don't think there is much if any difference in the majority of the airplane between the two. I intend to fly this one scale like and not so much bank and yank but I still want to make sure it's not going to come apart. :-)
10-05-2014, 04:44 PM
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Hi Erik
They all eat up a lot of real-estate for take off, like I mentioned before the main retracts are too far forward and the planes AOA should be more positive
I found the spacer under the nose retract does help , the best way I found for take off is to hold full up elevator on roll out and relax the elevator when the nose starts to rotate
As the plane is sitting on the ground push on the fin ,it takes a lot of force to lift the nose
I was spotting for my buddy who lost his at Wingham he got disoriented in a turn and pulled very hard on the elevator and it failed he is a very accomplished flyer but did not have enough time on the plane ( 2 flights )
Hope this helps
Good luck
Ted
They all eat up a lot of real-estate for take off, like I mentioned before the main retracts are too far forward and the planes AOA should be more positive
I found the spacer under the nose retract does help , the best way I found for take off is to hold full up elevator on roll out and relax the elevator when the nose starts to rotate
As the plane is sitting on the ground push on the fin ,it takes a lot of force to lift the nose
I was spotting for my buddy who lost his at Wingham he got disoriented in a turn and pulled very hard on the elevator and it failed he is a very accomplished flyer but did not have enough time on the plane ( 2 flights )
Hope this helps
Good luck
Ted
10-05-2014, 05:25 PM
#19
According to the instructions it says only to have 15 - 20mm of flap on takeoff, I can't see that being much more than about 15 degrees, they are pretty deep flaps. Only 30mm for landing. Curious as to if this is what guys have been using on them too. Seems like very little for landing.
10-05-2014, 05:53 PM
#21
I saw one lose a stabilator about 5 years ago. It just came off.
I flew one. It was very nice and groovy. Nose fell a bit in the turns. I have a kit but I plan to gut the main formers for a variety of reasons.
I flew one. It was very nice and groovy. Nose fell a bit in the turns. I have a kit but I plan to gut the main formers for a variety of reasons.
Last edited by mr_matt; 10-05-2014 at 07:59 PM.
10-06-2014, 01:23 PM
#24
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Hey Jeremy it was the SP
If you use more flap the elevator loses authority
The stab failure I saw ( I was spotting ) was during a turn when the pilot got disoriented the plane flipped inverted and he pulled full up he had quite a bit of speed and the left stab folded
You have the older kit with the aluminum rod this was a newer kit with a carbon tube
This plane needs to be flown with a little care during high speeds especially in a hard turn , the Peggy as you know is a little heavier but is a brick sh%& house almost indestructible ( LOL)
Ill send you some pics if I get home at a decent time if not tommorrow
Ted
If you use more flap the elevator loses authority
The stab failure I saw ( I was spotting ) was during a turn when the pilot got disoriented the plane flipped inverted and he pulled full up he had quite a bit of speed and the left stab folded
You have the older kit with the aluminum rod this was a newer kit with a carbon tube
This plane needs to be flown with a little care during high speeds especially in a hard turn , the Peggy as you know is a little heavier but is a brick sh%& house almost indestructible ( LOL)
Ill send you some pics if I get home at a decent time if not tommorrow
Ted
10-06-2014, 02:24 PM
#25
I have one that has been a real thrill for me every time I fly it. The F-5/T-38 has been my favorite jet since I was a child and to have one with a turbine has made the experience even sweeter. I lusted after the George Miller T-38 for years but never had one. I have a Titan in mine and I built it completely stock. Stock pipe, gear, stabs etc. The only mod I made was in order to get the pipe to not rub on the former for the vertical stab, I sanded quite a bit of it away so I fish plated it on both sides with some 1/8 inch aluminum I had laying around. That strengthened the former and made the stab nice and rigid.
I have probably 20 or so flights on mine now and am getting more comfortable with the landings which are pretty fast but totally controllable. Like you I thought the landing flap was a little less than it should be but as mentioned the flaps will blank the elevator with too much travel. I have the scratched wing tips to prove it...The jet has an attitude on landing that works well once you get in it. About 10-15 degrees nose high and let it sink. Once you have the runway made, pull back to idle and gently flare and she's home. I've seen you fly that JMP Firebird so this should be a piece of cake for you...just watch the pull on the corners and you will be fine. With the Titan I ball park my top speed well over 200, it's a rush for sure! Good luck with yours!
I have probably 20 or so flights on mine now and am getting more comfortable with the landings which are pretty fast but totally controllable. Like you I thought the landing flap was a little less than it should be but as mentioned the flaps will blank the elevator with too much travel. I have the scratched wing tips to prove it...The jet has an attitude on landing that works well once you get in it. About 10-15 degrees nose high and let it sink. Once you have the runway made, pull back to idle and gently flare and she's home. I've seen you fly that JMP Firebird so this should be a piece of cake for you...just watch the pull on the corners and you will be fine. With the Titan I ball park my top speed well over 200, it's a rush for sure! Good luck with yours!