Cyclic Hardover

My Feedback: (3)

Well, Congratulations! Since you know your final weight, you have been duely designated to put that thing in the air and report back to us. According to everybody involved here, your in the lead. What engine do you have up front.? Got any picture for us?

bob27s

My Feedback: (19)

Hopefully after I get my daughter's bedroom painted this week, I can start building mine!!

Its pretty sad when the kit collection not only collects dust, but starts mummifying !

jetpilotrich

Hey guys! I have been following some of the discussions on the AKM SU-27. I have finished mine and it is days from being flight ready. The CG has some issues. I would like to send a couple of pictures for everyone to check out and comment on. I have found some differences in the completed model and the plans.

Thanks

Rich

Blade47

I have added some more pictures of my Finished MIG29 on the balancer ( done today )... a good read about the C/G and the weight .

http://www.rcuniverse.com/forum/m_21..._4/key_/tm.htm

Pete

Joe Ortiz

My Feedback: (75)

Rich, post your pictures and build findings here, I have been following this thread myself, 'cause I was thinking about building this plane, seems everybody has the same CG concerns, maybe I'll wait until you guys fly yours and I'll get mine
Joe

Cyclic Hardover

My Feedback: (3)

Ohhhhhh boy! I have seen all this coming but not going to deal with it until its time. Those fins under the back end may take a beating. Have not decided on that deal yet. That whole back end is going to be very very close to the ground on landing. I have this composite stuff that is a very hard plastic looking sheet and I cut in tiny pieces and use them for skids on my shrike or wing tip protectors. I am going to try and mount them where they won't show much to protect the back end

jetpilotrich

Here is the first pic. Note that the CG is ahead of the Main gear on the plan but the gear is actually farther foward then it is in the plan which puts the CG behind the main gear. the plane sits ok on all 3 gear but this obviously puts the CG farther foward then it is on the plan! The gear mounting is foolproof..... the laser cut gear plate fits exactly between the F5 and F6 formers.... even the holes are laser cut for the retract screws. let me know if anyone has noticed this. Also note that the retracts are not to scale on the plan.... they are huge when compared to the actual retract unit.

I tried to upload the picture....if it does not show up I will try it again later.
Rich

Rudeboy

OK... Question:

I want to order my retracts... what exactly do I have to order?
I'm thinking: #101HD three gear system 3/16" struts, #117 hand pump with gauge, #132 hand pump coiled tubing, #143 right hand main strut 3/16", #144 left hand main strut 3/16".

Is that all I need, or are there things I am missing here?

The Spring Air pages aren't exactly well documented...

jetpilotrich

I used the 101HD which have a 3/16 wire, the 5-32 (regular 101) wires would just woble all over the place especially the nose gear.

Rich

Rudeboy

Yeah, but are the wires included with the retracts, or do you have to order them seperately?

AirGar

My Feedback: (7)

RudeBoy,

I have a set of Spring Air 302 HDR NIP I bought for my Starfire DF jet that's sitting here collecting dust. They look like 3/16", with air line and tank. Not sure if the exchange rate would allow us to do business or if they'd be a little heavy for the Flanker?

Gary

jetpilotrich

The 101HD set should come standard with the 3/16 wires. That is how mine came. I think the regular 101 set is the 5/32 wire version and the 101HD is the 3/16 version. The "HD" is the thicker wire.

Rich

Blade47

Snoop I have a "Q" for you ... with the spring air 101HD retracts ...will the package come with mounting bolts? If not what did you use to mount them?

Pete

Cyclic Hardover

My Feedback: (3)

No, I forgot what size I used but I have blind nuts on the back side. You also may have to grind down one corner of the main unit. That is another quirk I found. Take a good look at the plans on the flat display where it says" F-5 and right their is also a schematic of the retract. Look close and you'll see one corner which looks like its crossing over a line? Well , that corner of the retract is actually inside the fuselage. Apparently AKM mounted the retracts and built the side of the engine tubes over it.

This leads me to ask myself, "how do I remove the retract without ripping off part ot the wall? This is dumb so I ground off the corner to make it fit. Also if you are planning on glassing, Dont bother installing the blind nuts cuz you'll get slop all inside.

I found it------6-32's

Blade47

Cool thanks Snoop
Pete

Cyclic Hardover

My Feedback: (3)

get extra blind nuts, they tend to stick , or the bolts get stuck and twist around and stupid things. Using WD 40 helps when putting the bolts in

jetpilotrich

Hey guys!

No need to file down your expensive retract unit. Alex at AKM did a nice job designing it so you cut into the wood and insert the corner of the retract unit. I sent one of his pictures. It was intended that you notch out the wood, put the retract unit down on the retract gear plate and twist the unit under the wood and then screw it in place.

Hope this helps!

Rich

Cyclic Hardover

My Feedback: (3)

Good picture, I could not twist mine in so I "fixed it"

picard1

My Feedback: (2)

I started my wings over the weekend since my spring air 701 haven't arrived and I started looking into what modifcations are required to the fuse for 3/8 oleos. Also, after reading the discussions concerning the retract position relitave to the cg, I did some research on the position of the rear retracts. They appear to be further back behind CG, and swing forward in the retracted position. Take a look at the savage su-27.

So, my idea is to find the balance point on a completed retract with oleo's and tire, place that point on or forward of the CG. When retracts swing forward and lock the plane would balance when deployed this would shift CG to the rear creating a slightly nose heavy situation for landings.

Ok guys I am no engineer! so give me some feedback!!!

Picard

bob27s

My Feedback: (19)

Alex has had the design out and the plane flying for a few years now. The design has prooven out fairly well. Keep with the CG as on the plans, and you will be ok.

On an aircraft with this sort of fuselage surface area, more than just the wing comes into play when determining the cg. Keep that in mind.

The CG change from retracting the gear is negligable. There is also an aerodynamic pitching moment change that goes along with retracting/extending the gear. From looking at the geometry, id imagine they balance out for the most part.

On this type of plane, the last thing you really want is an overly-noseheavy condition for landing. You will run out of elevator in a hurry.

Rudeboy

Snoop,

Do you happen to have any idea how much weight the glass job added to the bare airframe weight?

I'm already wondering how I'm going to finish this thing... Mine seems to have a lot of hard (read heavy) balsa in it, and I don't want to make it an overweight brick. Looking at the pile of wood that still has to go into this thing, I can't help but wonder about the finished weight.
A film job would obviously be the lightest route... but this thing looks like a real bear to film finish...

PS: Check this one out! [link=http://www.umfc-kirchschlag.at/sites/su27projekt.htm]Harald Kafka's SU-27 Flanker[/link]

Cyclic Hardover

My Feedback: (3)

Well right now I am at about 5lbs after my glassing but no paint yet. What is on the plane other than the glass job was the retracts and a couple servos. So I think I am in good shape at the moment. If I can bring this in at around 8 1/2lbs, I'll be happy. That is what my red Ultra Sport 60 with my other Jett 90 weighs in at.

The guy who I have been talking with on this Minwax thing was the guy who had this Big Dauntless that won some best in show thing somewhere. He said that the overall weight increase using this method was far less than the traditional epoxy resin, plus it drys reall fast. Were talking a couple hours here. I can get several coats on in one day.

I only glassed the fuselage, I am covering the wings. Thats a piece of cake.

Cyclic Hardover

My Feedback: (3)

How about a picture of the whole thing?

jetpilotrich

Will get some out shortly. I just got a new camera and I want to get some great pictures for Alex and everyone. I just need to break in the engine and fly it. If weather permits and no other problems are found during the engine break-in/taxi tests.... I will probably fly it this weekend! But you know how that goes..... usually something needs to be tweaked or adjusted.

Hopefully I will have some pics by the end of the weekend......

Rich

Cyclic Hardover

My Feedback: (3)

You recall what your weighing in at?