Yellow Aircraft A-4 questions
03-06-2003, 07:12 AM
#1
Senior Member
Thread Starter
My Feedback: (8)
Join Date: Aug 2002
Location: Great Bend, Kansas
Posts: 506
Likes: 0
Received 0 Likes
on
0 Posts
Yellow Aircraft A-4 questions
OK, I hope I don't sound like a newbie here, but I's building my first D/F, and some questions are popping up.
I putting together a Yellow Aircraft A-4...and older model with the sport wing...here are my questions...
1. The instruction book says to install the servos for the Ailerons, Rudder, Throttle, and Retracts by applying silicone to the side and popping it in...and that makes me kinda nervous. I've been flying for about 5 years (with a 12 year break in the middle), and can't remember when I've broken a servo mount loose...unless I crash it. Is it really OK to mount the servo in this fashion???
2. Should the fan unit be absolutely center in the fuselage??? The former B1 is bigger on one side than it is the other...is it suppose to be like that, or is it time for surgery? Right now, the fan unit sits a little to the pilot's left.
3. I know the A-4 is suppose to set higher in the nose, but by how much??? Is there an incidence I should worry about here? What if there's not enough incidence, will it be frightful to get off the ground without stalling?
4. Down the road, what are the possibilities or retro-fitting a turbine??? I know I'm thinking waaay too fast about this, but wondered if it's worth it to convert it to turbine later, or build something else with turbine in mind in the first place.
5. Receiver antenna...it will be running in a tube down the inside of the fuselage...is it OK to be running it alongside the engine, or is this an RF worry? What about getting it close to any servos in the vicinity.
6. What do you think should be the realistic weight of this model finished ready for fuel...I'm using a OS 91 DF engine, Dynamax fan, plus I have an extra servo installed for nose gear steering (sure solved a linkage problem), plus another servo for an in-flight mixture control...plus Rom-air retracts (old but reliable)...
7. This goes along with the weight...I fly in Southern New Mexico, at 4400' altitude...with the 91, do you think this little thing will have to work to get off the ground? Our airfield has an 800' paved runway...am I going to be using all that length???
Can't think of anything else right now, but I'm sure more questions will be popping up later...give me your comments, concerns, helpful hints, and most of al, winning lottery numbers (for that turbine down the road...)
Thanks...Mark
I putting together a Yellow Aircraft A-4...and older model with the sport wing...here are my questions...
1. The instruction book says to install the servos for the Ailerons, Rudder, Throttle, and Retracts by applying silicone to the side and popping it in...and that makes me kinda nervous. I've been flying for about 5 years (with a 12 year break in the middle), and can't remember when I've broken a servo mount loose...unless I crash it. Is it really OK to mount the servo in this fashion???
2. Should the fan unit be absolutely center in the fuselage??? The former B1 is bigger on one side than it is the other...is it suppose to be like that, or is it time for surgery? Right now, the fan unit sits a little to the pilot's left.
3. I know the A-4 is suppose to set higher in the nose, but by how much??? Is there an incidence I should worry about here? What if there's not enough incidence, will it be frightful to get off the ground without stalling?
4. Down the road, what are the possibilities or retro-fitting a turbine??? I know I'm thinking waaay too fast about this, but wondered if it's worth it to convert it to turbine later, or build something else with turbine in mind in the first place.
5. Receiver antenna...it will be running in a tube down the inside of the fuselage...is it OK to be running it alongside the engine, or is this an RF worry? What about getting it close to any servos in the vicinity.
6. What do you think should be the realistic weight of this model finished ready for fuel...I'm using a OS 91 DF engine, Dynamax fan, plus I have an extra servo installed for nose gear steering (sure solved a linkage problem), plus another servo for an in-flight mixture control...plus Rom-air retracts (old but reliable)...
7. This goes along with the weight...I fly in Southern New Mexico, at 4400' altitude...with the 91, do you think this little thing will have to work to get off the ground? Our airfield has an 800' paved runway...am I going to be using all that length???
Can't think of anything else right now, but I'm sure more questions will be popping up later...give me your comments, concerns, helpful hints, and most of al, winning lottery numbers (for that turbine down the road...)
Thanks...Mark
03-07-2003, 06:31 PM
#2
Join Date: Dec 2002
Location: stoughton, WI,
Posts: 115
Likes: 0
Received 0 Likes
on
0 Posts
Yellow Aircraft A-4 questions
Mark,
I'm no jet expert either...I've been building a Yellow A-4 on and off for like 12 years! (more off than on...long story). As far as mounting the servos go, don't silicone them in. The servo I originally mounted for the elevator was a RCD Apollo 5, pretty much a standard servo. a couple of years ago, in one of my jet building fits, I felt this wasn't enough, and the geometry was wrong also. I wound up using a piece of nichrome wire to "saw" between the fuse and servo.
Try to get some kind of mounting arrangment that allows you to mount the servos with screws.
John
I'm no jet expert either...I've been building a Yellow A-4 on and off for like 12 years! (more off than on...long story). As far as mounting the servos go, don't silicone them in. The servo I originally mounted for the elevator was a RCD Apollo 5, pretty much a standard servo. a couple of years ago, in one of my jet building fits, I felt this wasn't enough, and the geometry was wrong also. I wound up using a piece of nichrome wire to "saw" between the fuse and servo.
Try to get some kind of mounting arrangment that allows you to mount the servos with screws.
John
03-08-2003, 07:34 AM
#3
Yellow Aircraft A-4 questions
Hi,
Sorry it's taken so long, but I actually wrote you a nice, long response just as my computer died. So, now that it's working again (though it's making all kinds of weird noises), I'll try again.
1. Don't silicone the servos in. Catspaw is right. Use conventional mounting methods. I don't know who wrote those instructions so many moons ago, but....
2. The fan unit should be in the center. I don't know how you got deformed bulkheads, but they shouldn't be that way. Fortunately, that shouldn't have too much of an effect on performance.
3. You can set your nose angle where you like it, so long as it is at least level. The FS A-4 sits very nose high, so I like to lengthen my nose struts accordingly, but the airplane will rotate fine with the bird sitting level.
4. I would never say you couldn't retrofit a turbine, but in this case, I would strongly discourage it. For one thing, you're talking about a VERY old kit. Who knows what condition the wood or the fiberglass is in. Second, out of all the jets out there, the Yellow A-4, especially the oldest one, wouldn't be anywhere near the top of my list of ones to convert. Don't get me wrong, I LOVE the Yellow A-4, but I just don't think it's a very good candidate for turbine retrofit compared to the other jets out there.
5. As far as Rx antennae go, I'm actually more concerned with running it along the pipe's length than near the engine. I've always routed mine externally, then secured it in some inconspicuous spot. I also like using base loaded whip antennae from Deans.
6. Look for a target weight of around 11 pounds. I've flown that plane all the way up to a 15 pound takeoff weight, but I've seen them built out at 9 pounds RTF, also. Obviously, the lighter, the better.
7. I've flown the A-4 at altitudes like yours with no problems. Again, keep it light. Make sure and do the aux air inlet so that your engine can suck some air from the nose gear door as well, otherwise you're going to need a lot of runway, and you may have problems with go-arounds. The A-4's inlets are very small, and the old kit was designed around a .45-size engine, so your .91 is going to have a hard time feeding.
Anyway, I hope this helps, and I'm sure there are lots of guys in here who've had a lot of stick time on this bird. Good luck, and feel free to call or email.
Sorry it's taken so long, but I actually wrote you a nice, long response just as my computer died. So, now that it's working again (though it's making all kinds of weird noises), I'll try again.
1. Don't silicone the servos in. Catspaw is right. Use conventional mounting methods. I don't know who wrote those instructions so many moons ago, but....
2. The fan unit should be in the center. I don't know how you got deformed bulkheads, but they shouldn't be that way. Fortunately, that shouldn't have too much of an effect on performance.
3. You can set your nose angle where you like it, so long as it is at least level. The FS A-4 sits very nose high, so I like to lengthen my nose struts accordingly, but the airplane will rotate fine with the bird sitting level.
4. I would never say you couldn't retrofit a turbine, but in this case, I would strongly discourage it. For one thing, you're talking about a VERY old kit. Who knows what condition the wood or the fiberglass is in. Second, out of all the jets out there, the Yellow A-4, especially the oldest one, wouldn't be anywhere near the top of my list of ones to convert. Don't get me wrong, I LOVE the Yellow A-4, but I just don't think it's a very good candidate for turbine retrofit compared to the other jets out there.
5. As far as Rx antennae go, I'm actually more concerned with running it along the pipe's length than near the engine. I've always routed mine externally, then secured it in some inconspicuous spot. I also like using base loaded whip antennae from Deans.
6. Look for a target weight of around 11 pounds. I've flown that plane all the way up to a 15 pound takeoff weight, but I've seen them built out at 9 pounds RTF, also. Obviously, the lighter, the better.
7. I've flown the A-4 at altitudes like yours with no problems. Again, keep it light. Make sure and do the aux air inlet so that your engine can suck some air from the nose gear door as well, otherwise you're going to need a lot of runway, and you may have problems with go-arounds. The A-4's inlets are very small, and the old kit was designed around a .45-size engine, so your .91 is going to have a hard time feeding.
Anyway, I hope this helps, and I'm sure there are lots of guys in here who've had a lot of stick time on this bird. Good luck, and feel free to call or email.
03-09-2003, 02:43 AM
#4
Senior Member
My Feedback: (1)
Join Date: Oct 2002
Location: Bossier City, LA,
Posts: 543
Likes: 0
Received 0 Likes
on
0 Posts
Yellow Aircraft A-4 questions
Hello:
Flew my A-4 today, finaly was rather forced to land it, I've heard alot of deadstick horror stories, but the place a alltitude left no choice, the jet came in and landed great.
Good luck with yours, it is a great flying jet!
Flew my A-4 today, finaly was rather forced to land it, I've heard alot of deadstick horror stories, but the place a alltitude left no choice, the jet came in and landed great.
Good luck with yours, it is a great flying jet!
03-09-2003, 04:04 AM
#5
Member
My Feedback: (2)
Join Date: Dec 2001
Location: Tampa, Florida
Posts: 95
Likes: 0
Received 0 Likes
on
0 Posts
Yellow Aircraft A-4 questions
Hi,
Built a few Yellow A-4's so here goes.
Keep it light. Keep aileron throws small, very sensitive. I put the rudder and elevator servos in the tail. If you are very lazy you could epoxy the aileron servos into the wings, they will probably out last your aircraft, but makes for difficult adjustments. I did one with split flaps, otherwise long glide rate. Keep nose wheel travel small, narrow gear tend to tip side to side with wings tips rubbing.
It you haven't installed the inlet, buy the new split inlet, much more thrust with this setup than the cheater hole. I can't stress this enough.
Did one with turbine. Weight 17 lb take off on 8.5 lb thrust. Pucker factor way high on take-off. Believe it or not, it did fly well once in the air.
Good luck,
George
Built a few Yellow A-4's so here goes.
Keep it light. Keep aileron throws small, very sensitive. I put the rudder and elevator servos in the tail. If you are very lazy you could epoxy the aileron servos into the wings, they will probably out last your aircraft, but makes for difficult adjustments. I did one with split flaps, otherwise long glide rate. Keep nose wheel travel small, narrow gear tend to tip side to side with wings tips rubbing.
It you haven't installed the inlet, buy the new split inlet, much more thrust with this setup than the cheater hole. I can't stress this enough.
Did one with turbine. Weight 17 lb take off on 8.5 lb thrust. Pucker factor way high on take-off. Believe it or not, it did fly well once in the air.
Good luck,
George
03-09-2003, 05:28 AM
#6
Senior Member
Thread Starter
My Feedback: (8)
Join Date: Aug 2002
Location: Great Bend, Kansas
Posts: 506
Likes: 0
Received 0 Likes
on
0 Posts
Yellow Aircraft A-4 questions
Thanks to all who responded...I think this will be a great flying plane...
On the ailerons I did come up with a fairly solid mount...I took 4 hardwood blocks...I laid the servo in the well, and sandwiched 2 hardwoods mounts on each side, tight enough so it holds the servo snug...then put a strap over the back to tie it down...works pretty well...I'll probably do the same with the fuselage servos. That nose sure will be full, with a retract tank, receiver, and a battery (and the nose gear servo).
Maybe this kit isn't so old, because I do have a split inlet...at least, I think that's what you are talking about. The intake is 2 pieces, which I join in the center around the fan unit...is that what you mean...and even then, they still recommend cutting a cheater hole...
And the fan is centered now...nice thing about wood...if it's not right, you can always make a new one...and the glass and foam are in fairly decent shape...I've got a Pattern plane that is about 15 years old...and the glass on it cracks really easily...but the jet glass doesn't crack.
Now that I think of it, it would be difficult to put turbine power in this thing...no room for fuel tanks!!!
Mark
On the ailerons I did come up with a fairly solid mount...I took 4 hardwood blocks...I laid the servo in the well, and sandwiched 2 hardwoods mounts on each side, tight enough so it holds the servo snug...then put a strap over the back to tie it down...works pretty well...I'll probably do the same with the fuselage servos. That nose sure will be full, with a retract tank, receiver, and a battery (and the nose gear servo).
Maybe this kit isn't so old, because I do have a split inlet...at least, I think that's what you are talking about. The intake is 2 pieces, which I join in the center around the fan unit...is that what you mean...and even then, they still recommend cutting a cheater hole...
And the fan is centered now...nice thing about wood...if it's not right, you can always make a new one...and the glass and foam are in fairly decent shape...I've got a Pattern plane that is about 15 years old...and the glass on it cracks really easily...but the jet glass doesn't crack.
Now that I think of it, it would be difficult to put turbine power in this thing...no room for fuel tanks!!!
Mark
