jetflyer

My Feedback: (5)

Curious about flying the Skymaster F-15 off grass fields. Would like to know the length of your field, wet weight, and turbine size along with how much runway are you eating up to get the F-15 airborne.

thanks,

JR

mugenkidd

My Feedback: (94)

WOW, i was thinking of posting the exact same thread.. If anyone has this info please share.

Smuttley

Very interested in this one myself as I have one on the bench almost ready to go with a P120 in it, I fly from a very nice grass strip about 80m long but surrounded by trees and am hoping to get it out and back!

Smuttley

On a related subject, I am having a little trouble with the elevons ie slack in the pivot shaft I am getting some play and was wondering if this is normal and can I get away with it in fight? Or do they suffer from flutter?

Lt. Dan

My Feedback: (21)

I fly from a 600ft, smooth, grass strip. Mine would take on average 300ft to get airborne with a P-120 at 32lbs wet take off weight (Jet Tech four tank set up) using a rolling start. Stopping at the end of the runway and letting the turbine spin up to full throttle before releasing the brakes shaved about 25-50ft from the roll.

Smuttley, what kind of slack are you experiencing? I went with HD ball links, HD aluminum servo arms, and titanium linkages and there was no play in the setup, but there was some play in the 8611 gear train. The plane flew smooth with that setup. (Elevon version)

Here are pictures of my linkage setup: http://www.kc-10.net/forum/showpost....&postcount=110

mugenkidd

My Feedback: (94)

Thanks for the info Lt. Dan. BTW how many flights do you have off of the grass. And how are the retracts/struts/airframe holding up, and are you using the skymaster "combo pack" retracts that are offered from dreamworks? Thanks again.

Michael

AirPac Models

Michael ,
Both Skymaster or Dreamworks offer Robart 630 retracts in the go fly combo pack. It's the same.

Erik R

My Feedback: (32)

Hi,
I flew my Simjet 2300 powered one almost exclusively off grass.It was aileron version,and carried 48oz smoke oil also.Takeoffs in 2-300 ft.A little flap shortens the roll.Lands in less.Will slow to a crawl,and extremely stable at high AOA approaches.Awesome airplane.Only reason I sold it was it was a little slow for my taste on the top end.Draggy airframe.Gear doors add 10-20
mph.Developed some stress cracks at the forwrd edge of the main gear door openings due to aircraft flexing on takeoff on grass.Mine was one of the first production ones to hit the states,and I think they have extended the carbon fiber reinforcement there now.You will love this plane.Straight and honest.Good luck.
Erik

Lt. Dan

My Feedback: (21)

I highly recommend the HD trunions from Seirra. The Robart retracts will get loose from the heavy weight combined with grass use. I used the Skymaster combo pack gear with no problems.

pilott34

I used HD ball links on mine too. On the other side I used the Dubro locking clevises with the H9 titanium pushrods. Not much slop at all on this setup. One thing I ABSOLUTELY recommend is strengthening the gear mount former. Its really not strong enough for grass ops in my opinion. I would put a CF plate on top of the mount. One thing I did was to laminate CF cloth between two pieces of 1/8" ply. While it was drying, I put it in my bench vice for a nice tight hold. When I removed the ply/cf laminate...I cut the piece to fit on top of the former from a paper template I made. Unfortunately, I did all of this AFTER I cracked the former.

Mike

Lt. Dan

My Feedback: (21)

I believe the newer models from the factory have these improvements already. We had early production models.

jetflyer

My Feedback: (5)

Great information guys. I do appreciate it as well as others too I see.

JR

lov2flyrc

My Feedback: (24)

Dan is correct, the B model has many improvements over the original C model. Carbon reinforced gear mounts, factory assembly with Hysol, additional scale detail, fiberglass canopy frame... just to name a few.
As Dan stated, the Sierra HD Trunions for the robart 630's are a must if flying this plane off grass.
Todd

Kevin Greene

My Feedback: (85)

I've seen Dan's F-15 fly from grass numerous times and it handled the grass strip well.....Even after the strip was heavily fertilized (Which made the grass grow very thick) Dan's plane handled the grass strip with ease. Additionally, Dan's F-15 has the full blown Jet Tech four tank setup. Even after a good 8 to 10 minute flight Dan's F-15 still had approximately 1/2 to 1/3 of fuel on board upon landing. If you carry less fuel your takeoff roll will be even shorter.

Kevin

Gordon Mc

My Feedback: (11)

I know a number of people who really hate pulling stuff out of their aircraft to fix issues like this. If you don't do so already, then maybe offering the Skymaster "Combo gear pack" with the heavy-duty trunions pre-installed would be a nice marketing touch ? (Or, if you guys are doing enough business with Robart, maybe you could have them simply supply improved trunions from the get-go rather than paying for original trunions AND replacements ?)

Just a thought ...

Gordon

Woketman

My Feedback: (6)

This is the first I've ever heard about these Sierra HD trunions. What is HD about them? What is different? How much? Do they go in with the criclips or the older style screwed in trunion? Thanks.

lov2flyrc

My Feedback: (24)

Gordon,
Thought of that, and already attempted to get Robart to make improvements to the 630 trunion, their reply was "Something to think about". For those that deal with Robart on a weekly basis, I somewhat hesitate to ask them to change anything, it takes ages just to get stock, changes would just delay me getting my regular product []
Aso considered a Upgrade combo with the HD trunions installed but, I have found some prefer the "Softer" trunion, theory being it is a built in flex plate. I now just offer a discount on the trunions when a combo pack is purchased, will install them for free if the customer wishes.

Woket,
There are two reasons the Sierra HD trunions are an improvement over the OEM units. First is of course material, the Sierra units are machined from 7075-T6 aluminum, much stronger metal. Second is the way the trunion is machined, Sierra has added a radius to the trunion fingers, eliminating the hard corner which is the weak spot on the OEM unit. The fingers also carry more material as seen below.... Pic one is an OEM trunion, Pic two is a Sierra HD. These are for the newer version of the 630 series, HD units are 27.95
Todd

BTW.... I also carry a Sierra HD trunion for the 635 series as well. Not really required for load, but due to the stronger material, the dont tend to develop the slop typically seen in the OEM unit

jetflyer

My Feedback: (5)

Todd,

How much are the Sierra HD trunion for the 635 series?

JR

lov2flyrc

My Feedback: (24)

JR,
The 635 Series are 32.95, found [link=http://dreamworksrc.com/catalog/product_info.php?products_id=633]Here[/link]

I put the wrong price above, the 630 series are 27.95