smchale

My Feedback: (67)

Chris,

How did the maiden go?

crhammond

My Feedback: (21)

Sean - no maiden yet.  Last weekend was too cold and windy, this weekend was awesome.  I flew yesterday and took the F86 but chickened out.  I was tired and nervous (I'm never nervous when I fly but I felt kinda rusty for some reason even though 2 weeks ago I was fine... )  One of the flyers I respect suggested that I need to fly something heavier and faster landing before trying the F86.  The Boomer just lands so slow and easy that it doesn't give you the idea of the pace things happen at.  My Comp-Arf Spark lands very fast and has a much higher wing loading than the F86 but you glide it in so its a totally different animal.

At the time I agreed with him that I maybe need an in-between step but I have since emailed with a few more folks and they told me a. I'll be fine and b. there really isn't any other way to get ready for a heavy scale jet - you just have to be aware oif what you should be doing and do it.  Also there is no in between step ... except maybe a Flash (but I don't want to buy another jet)

So ... lets hope for a good day this week and I WILL fly it.

I did put 7 flights on my Boomer and they were all fun.  I did not feel at all rusty by the time I went home and had the Boomer flying pretty well, turbine finally sorted out after some pump issues etc.  Some nice aerobatics and I had the speed up to 195km/h ... (its the Sprint so lots of drag.)  A monkey could land a Boomer so it isn't really an indication but the landings were really controlled and feathered in.

I've had a few heavy airplanes with more wing loading than the F86 but they have all been pretty forgiving of getting behind on the throttle.  I think I just have to trust myself and go for it.  I've just never been very nervous before with a new plane, IMAC, Pattern, whatever I just go for it.  I have maidined many, many airplanes for other guys.  I guess I have never put so much effort into a plane before... it's not the money aspect - all my planes are worth as much or more... it's just a strange feeling being unsure, normally I am just calm, the nerves make it hard to concentrate.

I think I'll try and find someone to go out with me and just spot.  Do the maiden without a crowd around, no one telling me what they think I should be doing on the approach etc.

aquaskiman

My Feedback: (46)

Get it up high, slow it down in landing configuration and fly it around a while. Find out how it flys slow and how much you can slow it down. I fly my SMF-86 at 5800ft and was surprised at the speed mine will drop a wing. George

smchale

My Feedback: (67)

Chris,
Take your time with it. You've done a great job in preparing it but there is no need to rush it. I finished mine off yesterday and will set up the throws etc today. Our field at the moment is in no shape to fly such a model so i'll have to wait until it is. However, this also gives me a chance to knock the winter rust off with some other models that can handle a less than ideal surface in the meantime. Keep us posted.

crhammond

My Feedback: (21)

crhammond

My Feedback: (21)

Oh yea - I used the throws and CG from the manual and they are just right.  The ailerons are a little sensitive around neutral so I may add some more expo.

5 mins is a safe flight time with 84 oz... I still had the 20oz hopper tank full but the main tanks were pretty much empty.

jclittle

My Feedback: (99)

Chris, congratulations on the 2 successful flights! I wouldn’t let the gear sticking damper your maiden success, sounds like you did a great job with a few challenges. What system are you using to control the gear? Also having just put a new Rabbit in my F86, I’m really hoping that taking the tanks off makes a big difference in performance, although not totally surprised as the Rabbit generates most of its power in the last 25% of throttle. Looking forward to your next report w/o the tanks to see how the Rabbit does on the F86.

Vincent

My Feedback: (61)

I never had any trouble with the gear on mine. What valving and how long is your door / gear delay set at. Also what pressure are you running and what size air tanks??
V..

crhammond

My Feedback: (21)

I am using an EV5U pro sequencer, 100 psi, 3 second open and close delays.  The gear liteally slams open and closed on the bench.
My plan is to lube the o-rings and make sure the retracts are locking solidly.  I'm not sure on the delays... they seem plenty long but I could make them longer.

I am going to play with the throttle curve / ECU setting to make the thrust vs. stick travel more linear.

crhammond

My Feedback: (21)

Air tanks are 250cc... 70psi was left when I landed the second time. Not sure on the first flight - likely more since I only cycled once.

I think on flight 2 the front doors hinge might have folded back on itself and stopped the gear from locking... I am going to put in some kind of stop to prevent that possability.

Vincent

My Feedback: (61)

I use 120lbs pressure and 5sec delay on the upside, 3 sec for the down cycle.
V..

FLYTICOUN

My Feedback: (14)

Hello Chris

Glad everything go fine on your made Chris!Do not forget to chek the cg again with out your wing tank!I want to see that plane fly too![8D]

Have a good one!
Eric.

crhammond

My Feedback: (21)

My ECU is set to full expo - I think I am going to try half expo. There is a very significant difference in thrust with each click above 70%... if I can get a flatter feel above 50% it will feel more natural to fly. The current setup feels like a lead sled - but I don't think it actually is. I am going to see what the vertical is like next time... the take off and climb out was certainly no issue.

I haven't downloaded the ECU data yet... but that will let me know if I was getting full RPM's/temps etc... could be my duct is not providing enough air but the turbine certainly seemed to be running correctly.

Vincent

My Feedback: (61)

I flew my Sabre with a P-80 (19lbs) and it went well but when i replaced the 80 with a 120 the jet really came alive. Much more fun and grooved real nice with the added power.
V..

crhammond

My Feedback: (21)

I checked the data and cruise speed RPM's are around 120,000.  It is definately hitting full RPM's (153,000.)  Max temps are 520, most of the time it is in the 480/490 range.  That tells me it is getting enough air and running correctly.  Pump power is nice and low (lower than my other Rabbit.)

I will fly it some more before I draw any conclusions.  I think a 24lb turbine would be about ideal... but it may yet turn out to be okay once I get it all cleaned up.  I am going to set up a throttle curve that puts 120,000 RPM at about 60% travel which should make the feel better.

I only have 84oz fuel capacity... based on that the only real alternative for a larger turbine would be a Hawk 100R.  24lbs thrust and lower fuel milage... it would likely be a very good combination, but I am going to have to do my best to make it work with the Rabbit.  Other folks have Rabbit's and they seem to have enough power.  I am flying from a runway at 3,100 ft and even higher altitude density (low humidity)... makes a big difference.

smchale

My Feedback: (67)

Certainly is! Congrats Chris on the maiden flight. Your patience and attention to detail has certainly paid off. Thanks for sharing your build with us!! What was your final AUW wet ready to fly?

crhammond

My Feedback: (21)

I'm almost ready to give it another try after working on it last night. I am out of town for Spring/Easter break now so it won't be until April 5, 6, 7 some time in there.

I found out that one of the steering cable elastics had broken so the wheel was hanging up on the wire causing it not to fully retract and lock. The front door was folding flat on opening and preventing the retract from locking down. In fact I'm surprised it even came down in the air as there is a ton pf pressure when that door is flat and the spring that causes it to banjoe works against the retract too.

I lubed the retracts and o-rings, fixed up the front door and steering wires, re-lubed the door cylinder o-rings, changed the retract air lines just because and set the pressure to 110 PSI... leak checked it all. It cycles perfectly now, everything is locking as it should and nothing is leaking. The air system is using 10 PSI per cycle so I don't get that many really strong cycles from it. I upped my gear failsafe to70 PSI. Timers are set to 5 seconds (which seems like an eternity on the bench!)

Wing tanks are off. Dry weight is now 21.5 lbs and I need to remove some nose weight as the CG has moved forward about 2 or 3 mm. I think it will be very close to 21lbs dry once I re-balance (25 ish wet.) I am really hoping those tanks were adding a lot of drag... 1+ lbs less sure won't hurt.

I am also going to set the ECU to Linear onEric C's recommendation. He flys his F86 without the tanks and has plenty of performance for big loops etc.

I will eventually make some extensions to run my ducting up closer to the turbine but I want to try without the tanks and with properly retracting gear first.

Worst case - my backup plan is a Hawk 100R turbine

Eddie P

My Feedback: (4)

My personal opinion is the wing tanks will make a difference in the throttle settings required for given speeds, and the drop in weight will also be noticeable at the thrust levels you are at. Tam's F-86 (EDF) is a little lighter in a realistic comparison. I've flown it, and it is a sweet machine. Absolutely wonderful to fly and lands relatively slowly for a scale jet. But keep in mind the EDF version it isn't landing with an extra 20 ounces of fuel plus a full UAT - our turbine birds have a few "secret" pounds of weight riding along, and with some residual thrust of an idling turbine engine in the flare. That can lead to fast landings if they are not spot on, well, that just leads to faster landings period unless you like inverted landings Ask me, I do the same thing inadvertently with my A-4. I have a really hard time matching the short field performance of a similar weight EDF A-4 as I still have a full UAT, nearly full 16 ounce hopper and an idling Supersport to account for. But, we have the advantage of some really great high end performance with turbines and all the other little nice touches turbines bring to the table, especially for a scale jet.

Having more confidence in the landing gear after the fixes will probably also bring some added enjoyment. Good luck and have fun getting her dialed in.

Eddie P

My Feedback: (4)

Did you mix any crow into the ailerons with flap deployment? I wonder if that would help?

aquaskiman

My Feedback: (46)

No crow in the ail.

Vincent

My Feedback: (61)

Without having the extra power removing the wing tanks will certainly improve the handling of any jet. The Sabre is a sweetheart to land and no crow is required. There is very little change in pitch when the flaps are deployed, i dont have any mix on elev.
V..

crhammond

My Feedback: (21)

No mix at all is needed... the flaps drop and it just slows down (not much though HA HA.)

Anders at Hawk Turbine feels the Hawk 100R is too much for this jet and will not fit... and even if it did would likely cause structural failure.  I doubt it.  The Hawk is really the only other viable choice so I will have to make the Rabbit work.

So lets hope cleaning it up will do the trick.  Too bad though as I would like to be able to use the tanks for looks and just in case the gear ever fails.

I am going to go to the effort of re-ducting so the duct spills in front of the turbine and maybe even do a full bypass if I can figure out how to fit it in.

I'm away on vacation now.  The Saber will most likely fly again on April 10th.

jclittle

My Feedback: (99)

Chris - do you really believe the lack of ducting going all the way to the turbine intake created so much drag? I was considering a similar set up and would be very interested to hear others weigh in on this. Thanks!

crhammond

My Feedback: (21)

I don't know - but the BVM guys here are telling me that

The bypass would reduce noise too. But its a lot of work so if the tanks clean it up and the ECU curve makes the feel better it might be okay. I will know in a couple of weeks when I test fly again.

If I make the bypass it will be like the Comp-Arf Mig 15 (sweet jet also on my list of future projects.) Pic attached. If I go to the effort I will make a mold so I can make more for others.

aquaskiman

My Feedback: (46)

In this pic you can see my ducting that I used after moving the turbine 2 inches forward.